Computer-Based Guidelines for

Concrete Pavements, Volume II:

Design and Construction Guidelines

and HIPERPAV® II User’s Manual 

PUBLICATION NO. FHWA-HRT-04-122 FEBRUARY 2005

Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296
FOREWORD 

 

This report documents the investigation, modeling and validation of the enhanced High 

PERformance PAVing (HIPEPAV®) II, a comprehensive, yet user-friendly software package. 

HIPERPAV II primarily incorporates a set of guidelines for the proper selection of design and 

construction variables to minimize early-age damage to Jointed Plain Concrete Pavement (JPCP) and 

Continuously Reinforced Concrete Pavement (CRCP). In addition, the software determines the effect of 

early-age behavior factors on JPCP long-term performance. This report, Volume II of a three-volume set, 

is the Construction and Design Guidelines and HIPERPAV II User’s Manual, which provides general 

instructions on the use and application of the HIPERPAV II. Volume I is the Project Summary 

documenting the efforts undertaken for the development of the guidelines. Volume III is the Technical 

Appendices, which documents the investigation, modeling, and validation of the HIPEPAV II. 

HIPERPAV II software program will be available on a CD, or will be downloadable from FHWA Web 

site http://www.tfhrc.gov/pavement/pccp/hipemain.htm. 

This report will be of interest to those involved in concrete pavement mix design, as well as the 

design and construction of concrete pavements. Sufficient copies of this report and CD software program 

are being distributed to provide two copies to each Federal Highway Administration (FHWA) Resource 

Center, two copies to each FHWA Division Office, and a minimum of four copies to each State highway 

agency. Additional copies for the public are available from the National Technical Information Services 

(NTIS), 5285 Port Royal Road, Springfield, VA 22161. 

 T. Paul Teng, P.E. 

 Director, Office of Infrastructure 

 Research and Development 

Notice 

This document is disseminated under the sponsorship of the U.S. Department of Transportation in 

the interest of information exchange. The U.S. Government assumes no liability for the use of the 

information contained in this document. This report does not constitute a standard, specification, or 

regulation. 

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ 

names appear in this report only because they are considered essential to the objective of the document. 

Quality Assurance Statement 

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards and 

policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. 

FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous 

quality improvement. 
1. Report No 2. Government Accession No. 3. Recipient's Catalog No. 

FHWA–HRT–04–122 N/A N/A 

4. Title and Subtitle 5. Report Date 

 February 2005 

 

6. Performing Organization Code 

 

Computer-Based Guidelines For Concrete Pavements Volume II—Design and 

Construction Guidelines and HIPERPAV II User’s Manual 

N/A 

7. Authors(s) 8. Performing Organization Report No. 

J. Mauricio Ruiz, Robert O. Rasmussen, George K. Chang, Jason C. Dick, 

Patricia K. Nelson

 N/A 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

N/A 

11. Contract or Grant No. 

DTFH61-00-C-00121 

13. Type of Report and Period Covered 

The Transtec Group, Inc. 

1012 East 38 1⁄2 Street 

Austin, TX 78751 

 Final Report— 

 February 2000 to April 2004

12. Sponsoring Agency Name and Address 14. Sponsoring Agency Code 

 

Office of Infrastructure Research and Development 

Federal Highway Administration 

6300 Georgetown Pike 

McLean, VA 22101 

 

15. Supplementary Notes 

Contracting Officer’s Technical Representative: Fred Faridazar, HRDI–11

 

16. Abstract 

This report documents enhancements incorporated in the (HIgh PERformance PAVing) HIPERPAV® II software. Enhancements made within 

this project include the addition of two major modules: a module to predict the performance of Jointed Plain Concrete Pavement (JPCP) as affected by 

early-age factors and a module to predict the early-age behavior (first 72 hours) and early life (up to 1 year) of Continuously Reinforced Concrete Pavement 

(CRCP). Two additional Federal Highway Administration (FHWA) studies were also incorporated: one that predicts dowel bearing stresses as a function 

of environmental loading during the early age and a module for optimization of concrete paving mixes as a function of 3-day strength, 28-day strength, and 

cost. Additional functionality to the software also was incorporated by reviewing and prioritizing the feedback provided by users of the first generation of 

the software, HIPERPAV I. 

This volume provides a comprehensive set of guidelines useful in designing and constructing both JPCP and CRCP concrete pavements. In 

addition, this document also provides sample case studies that illustrate the proper use of HIPERPAV II to optimize concrete pavement behavior and 

contains a user’s manual for HIPERPAV II. This is the second volume in a series of three volumes that document the different tasks carried out in 

accomplishing the objectives for this project. 

FHWA No. Vol. No. Short Title

FHWA-HRT-04-121 Volume I Project Summary 

FHWA-HRT-04-122 Volume II Design and Construction Written Guidelines and HIPERPAV II User’s Manual 

FHWA-HRT-04-127 Volume III Technical Appendices 

17. Key Words 18. Distribution Statement 

High Performance Concrete Pavement; HIPERPAV; 

Jointed; Continuously Reinforced; Early-Age Behavior; 

Long-Term Performance; Mechanistic-Empirical Models; 

Temperature; Hydration; Shrinkage; Relaxation; Creep; 

Thermal Expansion; Slab Base Restraint; Curling; 

Warping; Plastic shrinkage; Cracking; JPCP; CRCP

No restrictions. This document is available to the 

Public through the National Technical Information Service; 

Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

 Unclassified Unclassified 173 N/A 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized (art. 5/94) 
ii 

SI* (MODERN METRIC) CONVERSION FACTORS 

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol 

LENGTH 

in inches 25.4 millimeters mm 

ft feet 0.305 meters m 

yd yards 0.914 meters m 

mi miles 1.61 kilometers km 

AREA 

in2 square inches 645.2 square millimeters mm2

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2

ac acres 0.405 hectares ha 

mi2 square miles 2.59 square kilometers km2

VOLUME 

fl oz fluid ounces 29.57 milliliters mL 

gal gallons 3.785 liters L 

ft3 cubic feet 0.028 cubic meters m3 

yd3 cubic yards 0.765 cubic meters m3 

NOTE: volumes greater than 1000 L shall be shown in m3

MASS 

oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") 

TEMPERATURE (exact degrees) o

F Fahrenheit 5 (F-32)/9 Celsius oC 

or (F-32)/1.8 

ILLUMINATION 

fc foot-candles 10.76 lux lx 

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS 

lbf poundforce 4.45 newtons N 

lbf/in2 poundforce per square inch 6.89 kilopascals kPa 

APPROXIMATE CONVERSIONS FROM SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

LENGTH

mm millimeters 0.039 inches in 

m meters 3.28 feet ft 

m meters 1.09 yards yd 

km kilometers 0.621 miles mi 

AREA mm2

 square millimeters 0.0016 square inches in2 

m2 square meters 10.764 square feet ft2 

m2 square meters 1.195 square yards yd2 

ha hectares 2.47 acres ac 

km2 square kilometers 0.386 square miles mi2 

VOLUME 

mL milliliters 0.034 fluid ounces fl oz 

L liters 0.264 gallons gal 

m3 cubic meters 35.314 cubic feet ft3 

m3 cubic meters 1.307 cubic yards yd3 

MASS 

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T 

TEMPERATURE (exact degrees) o

C Celsius 1.8C+32 Fahrenheit oF 

ILLUMINATION 

lx lux 0.0929 foot-candles fc 

cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS 

N newtons 0.225 poundforce lbf 

kPa kilopascals 0.145 poundforce per square inch lbf/in2

*SI is the symbol for th International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E e 380. 

(Revised March 2003)
iii 

TABLE OF CONTENTS 

CHAPTER 1. INTRODUCTION............................................................................................... 1

1.1 BACKGROUND ............................................................................................................... 1

1.2 OBJECTIVES ................................................................................................................... 2

1.3 SCOPE AND FORMAT................................................................................................... 2

CHAPTER 2. EARLY-AGE PAVEMENT BEHAVIOR........................................................ 5

2.1 GENERAL......................................................................................................................... 5

2.1.1 Temperature and Moisture Changes........................................................................5

2.1.2 Development of Concrete Properties ........................................................................6

2.1.3 Development of Stresses.............................................................................................7

2.1.4 Thermal Cracking ....................................................................................................10

2.2 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE OF 

JPCP................................................................................................................................. 10

2.2.1 Physical Mechanisms Governing Joint Opening at Early Ages ...........................10

2.2.2 Effect of Joint Opening on Load Transfer Efficiency—JPCP without Dowels ..11

2.2.3 Effect of Joint Opening on Load Transfer Efficiency—JPCP with Dowels........12

2.2.4 Distresses Influenced by Joint Opening—JPCP without Dowels.........................12

2.2.5 Distresses Influenced by Joint Opening—JPCP with Dowels ..............................13

2.3 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE OF 

CRCP ............................................................................................................................... 13

2.3.1 Crack Spacing...........................................................................................................14

2.3.2 Crack Width .............................................................................................................15

2.3.3 Steel Stress.................................................................................................................15

2.3.4 Factors Affecting Crack Spacing, Crack Width, and Steel Stress .......................15

2.4 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE 

COMMON TO JPCP AND CRCP................................................................................ 16

2.4.1 Delamination.............................................................................................................16
iv 

2.4.2 Built-In Curling ........................................................................................................18

CHAPTER 3. EARLY-AGE PAVEMENT DISTRESSES ................................................... 25

3.1 PLASTIC SHRINKAGE CRACKING......................................................................... 25

3.2 CRACKING DUE TO THERMAL SHOCK ............................................................... 26

3.2.1 Distress Manifestation on JPCP..............................................................................27

3.2.2 Distress Manifestation on CRCP ............................................................................27

3.2.3 Recommended Precautions against Thermal Shock .............................................28

CHAPTER 4. IMPACT OF EARLY-AGE BEHAVIOR ON LONG-TERM 

PERFORMANCE....................................................................................................................... 31

4.1 FAULTING OF JPCP WITHOUT DOWELS............................................................. 31

4.1.1 Early-Age Inputs ......................................................................................................31

4.1.2 Materials Characterization......................................................................................32

4.1.3 Early-Age Response..................................................................................................33

4.1.4 Pavement Behavior...................................................................................................33

4.1.5 Long-Term Inputs ....................................................................................................33

4.1.6 Distress Prediction....................................................................................................34

4.1.7 Long-Term Performance .........................................................................................35

4.2 FAULTING OF JPCP WITH DOWELS ..................................................................... 35

4.2.1 Early-Age Inputs ......................................................................................................36

4.2.2 Materials Characterization......................................................................................37

4.2.3 Early-Age Response..................................................................................................37

4.2.4 Pavement Behavior...................................................................................................38

4.2.5 Long-Term Inputs ....................................................................................................38

4.2.6 Distress Prediction....................................................................................................38

4.2.7 Long-Term Performance .........................................................................................39

4.3 JPCP TRANSVERSE CRACKING.............................................................................. 39

4.3.1 Early-Age Inputs ......................................................................................................40
v 

4.3.2 Materials Characterization......................................................................................41

4.3.3 Early-Age Response..................................................................................................42

4.3.4 Pavement Behavior...................................................................................................43

4.3.5 Long-Term Inputs ....................................................................................................43

4.3.6 Distress Prediction....................................................................................................45

4.3.7 Long-Term Performance .........................................................................................46

4.4 JPCP CORNER CRACKING ....................................................................................... 47

4.4.1 Early-Age Inputs ......................................................................................................47

4.4.2 Materials Characterization......................................................................................48

4.4.3 Early-Age Response..................................................................................................48

4.4.4 Pavement Behavior...................................................................................................49

4.4.5 Long-Term Inputs ....................................................................................................49

4.4.6 Distress Prediction....................................................................................................49

4.4.7 Long-Term Performance .........................................................................................50

4.5 DELAMINATION SPALLING..................................................................................... 51

4.5.1 Early-Age Inputs ......................................................................................................52

4.5.2 Material Characterization .......................................................................................53

4.5.3 Pavement Response ..................................................................................................54

4.5.4 Pavement Behavior...................................................................................................54

4.5.5 Long-Term Inputs ................................................................................................... 55

4.5.6 Distress Prediction....................................................................................................55

4.5.7 Pavement Long-Term Performance History .........................................................57

4.6 DEFLECTION SPALLING........................................................................................... 57

4.6.1 Early-Age Inputs ......................................................................................................58

4.6.2 Materials Characterization......................................................................................58

4.6.3 Early-Age Response..................................................................................................59
vi 

4.6.4 Pavement Behavior...................................................................................................59

4.6.5 Long-Term Inputs ....................................................................................................59

4.6.6 Distress Prediction....................................................................................................60

4.6.7 Long-Term Performance .........................................................................................60

4.7 PUNCHOUTS ................................................................................................................. 61

4.7.1 Early-Age Inputs ......................................................................................................62

4.7.2 Material Characterization .......................................................................................62

4.7.3 Pavement Response ..................................................................................................62

4.7.4 Pavement Behavior...................................................................................................62

4.7.5 Long-Term Inputs ....................................................................................................62

4.7.6 Distress Prediction....................................................................................................63

4.7.7 Pavement Long-Term Performance History .........................................................64

CHAPTER 5. HIPERPAV II INPUT PARAMETERS ......................................................... 67

5.1 DESIGN INPUTS ........................................................................................................... 67

5.1.1 Pavement Type .........................................................................................................68

5.1.2 Thickness...................................................................................................................68

5.1.3 Joint Spacing.............................................................................................................68

5.1.4 Reliability ..................................................................................................................69

5.1.5 Drainage ....................................................................................................................69

5.1.6 Support Layers .........................................................................................................69

5.1.7 Load Transfer ...........................................................................................................70

5.1.8 Reinforcement...........................................................................................................71

5.2 MATERIALS AND MIX DESIGN INPUTS ............................................................... 72

5.2.1 Aggregates.................................................................................................................72

5.2.2 Cement.......................................................................................................................74

5.2.3 Chemical Admixtures...............................................................................................75
vii 

5.2.4 Supplementary Cementitious Materials.................................................................76

5.2.5 Mix Design.................................................................................................................77

5.2.6 Strength and Maturity .............................................................................................77

5.2.7 PCC Modulus of Elasticity ......................................................................................78

5.3 CLIMATIC INPUTS...................................................................................................... 78

5.3.1 Early-Age Climatic Inputs.......................................................................................78

5.3.2 Long-Term Climatic Inputs.....................................................................................79

5.4 CONSTRUCTION INPUTS .......................................................................................... 80

5.4.1 Curing........................................................................................................................80

5.4.2 Time of Day of Construction ...................................................................................81

5.4.3 Initial PCC Mix Temperature.................................................................................82

5.4.4 Sawcutting Methods and Timing ............................................................................83

5.4.5 Initial Subbase Temperature...................................................................................84

5.5 TRAFFIC LOADING INPUTS..................................................................................... 84

5.5.1 Load Configuration..................................................................................................84

5.5.2 Classification.............................................................................................................84

5.5.3 Traffic Volume, Growth Rate, and Distribution ...................................................85

CHAPTER 6. CASE STUDIES ................................................................................................ 87

6.1 PROACTIVE JPCP CASE STUDY: TIME OF PLACEMENT................................ 87

6.1.1 Background...............................................................................................................87

6.1.2 HIPERPAV II Analysis Strategy ............................................................................88

6.1.3 Solution......................................................................................................................89

6.1.4 Long-Term Performance .........................................................................................90

6.2 POST-MORTEM JPCP CASE STUDY: FAULTING................................................ 91

6.2.1 Background...............................................................................................................91

6.2.2 Analysis Strategy ......................................................................................................91
viii 

6.2.3 Solution......................................................................................................................92

6.3 PROACTIVE CRCP STUDY: SEASONAL TEMPERATURE DROP.................... 93

6.3.1 Background...............................................................................................................93

6.3.2 Analysis Strategy ......................................................................................................94

6.3.3 Solution......................................................................................................................94

6.4 POST-MORTEM CRCP CASE STUDY: AGGREGATE SELECTION ................. 96

6.4.1 Background...............................................................................................................96

6.4.2 Analysis Strategy ......................................................................................................96

6.4.3 Solution......................................................................................................................97

CHAPTER 7. HIPERPAV II USER’S MANUAL ................................................................. 99

7.1 PROJECT INFORMATION ......................................................................................... 99

7.1.1 Geography Screen ..................................................................................................100

7.1.2 Monthly Weather Data Screen..............................................................................101

7.2 EARLY-AGE JPCP ANALYSIS................................................................................. 102

7.2.1 Strategies .................................................................................................................102

7.2.2 Design Inputs ..........................................................................................................104

7.2.3 Materials and Mix Design Inputs..........................................................................107

7.2.4 Construction Inputs................................................................................................113

7.2.5 Environment ...........................................................................................................115

7.2.6 Early-Age JPCP Analysis ......................................................................................118

7.3 JPCP LONG-TERM COMPARATIVE ANALYSIS................................................ 122

7.3.1 Long-Term Strategy Information .........................................................................123

7.3.2 Performance Parameters .......................................................................................124

7.3.3 Joint Design.............................................................................................................125

7.3.4 Traffic Inputs..........................................................................................................126

7.3.5 Long-Term Analysis...............................................................................................129
ix 

7.3.6 Multiple Long-Term Comparative Strategies .....................................................131

7.3.7 Early-Age and Long-Term JPCP Analysis—Sample Scenario..........................131

7.4 EARLY-AGE CRCP ANALYSIS ............................................................................... 138

7.4.1 Early-Age CRCP Strategies Section .....................................................................138

7.4.2 CRCP Design Inputs ..............................................................................................138

7.4.3 Materials and Mix Design Inputs..........................................................................140

7.4.4 Construction............................................................................................................140

7.4.5 Environment ...........................................................................................................141

7.4.6 Post 72-Hour Temperatures ..................................................................................141

7.4.7 CRCP Analysis .......................................................................................................142

7.4.8 Interpretation of CRCP Analysis..........................................................................144

7.5 HIPERPAV II Reports................................................................................................. 145

7.6 COMET Module ........................................................................................................... 146

REFERENCES.......................................................................................................................... 157
x 

LIST OF FIGURES 

Figure 1. Conceptual representation of temperature development in a concrete element with time. ..........9

Figure 2. Conceptual effect of creep/relaxation on concrete stresses.(11)...................................................10

Figure 3. Schematic of joint opening due to temperature drop (–∆T). ......................................................11

Figure 4. Schematic of joint in JPCP without dowels................................................................................11

Figure 5. Schematic of JPCP after loss of aggregate interlock/load transfer at the joint...........................12

Figure 6. Schematic of doweled joint in JPCP...........................................................................................12

Figure 7. Conceptual reduction in mean crack spacing over time.(16)........................................................14

Figure 8. Moisture gradient resulting from excessive moisture loss...........................................................17

Figure 9. Effect of drying shrinkage and thermal gradient on curling and warping (thermal gradient 

at set = 0 and thermal gradient at time t = 0). ......................................................................................19

Figure 10. Effect of drying shrinkage and thermal gradient on curling and warping (thermal gradient 

at set = 0 and thermal gradient at time t is positive). ...........................................................................19

Figure 11. Effect of drying shrinkage and thermal gradient on curling and warping (thermal gradient 

at set = 0 and thermal gradient at time t is negative). ..........................................................................20

Figure 12. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set 

is positive and thermal gradient at time t = 0). ....................................................................................20

Figure 13. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set 

is positive and thermal gradient at time t is positive). .........................................................................21

Figure 14. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set 

is positive and thermal gradient at time t is negative). ........................................................................21

Figure 15. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set 

is negative and thermal gradient at time t = 0). ...................................................................................22

Figure 16. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set 

is negative and thermal gradient at time t is positive). ........................................................................22

Figure 17. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set 

is negative and thermal gradient at time t is negative).........................................................................23

Figure 18. Plastic shrinkage cracking in concrete pavement. ....................................................................25

Figure 19. Closely spaced cracks resulting from thermal shock in CRCP. ...............................................27

Figure 20. Longitudinal crack in CRCP due to thermal shock. Crack is enhanced for clarity. ................28
xi 

Figure 21. Flowchart outlining impact of early-age input on long-term faulting performance of JPCP 

without dowels.....................................................................................................................................32

Figure 22. Deflected pavement shape. .......................................................................................................33

Figure 23. Schematic of faulting progression in JPCP without dowels, wheel on leave edge of slab 

(exaggerated to show mechanism).......................................................................................................34

Figure 24. Schematic of faulting progression in JPCP without dowels, wheel on approach edge 

of slab ..................................................................................................................................................34

Figure 25. Schematic of faulting progression in JPCP without dowels, resultant behavior at the 

JPCP joint that causes faulting ............................................................................................................34

Figure 26. Photograph of faulting in JPCP. ...............................................................................................35

Figure 27. Schematic of time growth of faulting for JPCP without dowels. .............................................35

Figure 28. Flowchart outlining the influence of early-age properties on long-term faulting 

performance of JPCP with dowels.......................................................................................................36

Figure 29. Schematic of ideal JPCP at set (dowel bar straight). ................................................................37

Figure 30. Schematic of curled JPCP connected by a dowel in bending (enlarged to show mechanism). 38

Figure 31. Schematic of wheel load on JPCP with dowels (dowel enlarged to show bearing stresses). ...38

Figure 32. Schematic of time and traffic growth of faulting for JPCP with doweled joints......................39

Figure 33. Flowchart outlining impact of early-age input on long-term transverse cracking 

performance of JPCP. .......................................................................................................................... 41

Figure 34. Schematic of JPCP with a positive temperature gradient at set................................................42

Figure 35. Schematic of JPCP with a negative temperature gradient at set...............................................42

Figure 36. Schematic of curled-down JPCP. Note the pavement lifts off the subbase at midslab, and 

its edges bear on the subbase. .............................................................................................................. 43

Figure 37. Plan view of JPCP slab showing location of critical edge stresses that cause transverse 

cracking at midslab..............................................................................................................................44

Figure 38. Schematic of curled-up JPCP. ..................................................................................................44

Figure 39. Schematic of top-down JPCP transverse cracking due to severe erosion of subbase...............45

Figure 40. Photograph of transverse crack. Transverse crack and joints enhanced for clarity.................46

Figure 41. Schematic of long-term performance of JPCP: Percent cracked slabs vs. time. .....................46

Figure 42. Flowchart outlining the influence of early-age properties on long-term JPCP corner breaks..48
xii 

Figure 43. Schematic of top-down JPCP corner cracking in pavements with built-in curling and 

reduced subbase support and load transfer. Wheel loading results in top-down cracking. ................ 49

Figure 44. Photograph of corner breaks. Joints and corner breaks are enhanced for clarity. ...................50

Figure 45. Plan view of JPCP showing a corner break..............................................................................50

Figure 46. History of JPCP corner breaks..................................................................................................51

Figure 47. Flowchart outlining impact of early-age input on long-term delamination spalling distress 

for JPCP and CRCP.............................................................................................................................52

Figure 48. Relative humidity as a function of slab depth. .........................................................................53

Figure 49. Strength development as a function of slab depth....................................................................54

Figure 50. Shear stresses as a function of slab depth.................................................................................54

Figure 51. Delamination mechanism. ........................................................................................................55

Figure 52. Vertical cracks at delaminated areas leading to spalling distress. ............................................55

Figure 53. Delamination spalling at a CRCP crack. ..................................................................................56

Figure 54. Round-shaped aggregates at a spalled CRCP crack. ................................................................56

Figure 55. Spalling progression as a function of evaporation rate.(16) .......................................................57

Figure 56. Flowchart outlining the impact of early-age input on long-term deflection spalling 

performance for JPCP and CRCP........................................................................................................58

Figure 57. Schematic of deflection spalling mechanism. ..........................................................................59

Figure 58. Schematic of deflection spalling mechanism. ..........................................................................59

Figure 59. Photograph of deflection spalling on a CRCP..........................................................................60

Figure 60. Schematic of percent JPCP spalled joints/cracks vs. time........................................................60

Figure 61. Flowchart outlining impact of early-age input on long-term punchout distress of CRCP. ......61

Figure 62. Schematic of position of tensile stresses in CRCP. ..................................................................63

Figure 63. CRCP longitudinal and transverse stresses in CRCP as a function of crack spacing...............63

Figure 64. Typical CRCP punchout distress..............................................................................................64

Figure 65. CRCP punchout progression with time. ...................................................................................65

Figure 66. Typical temperature development in the slab for concrete placement at 10 a.m......................88

Figure 67. Typical temperature development in the slab for concrete placement at 8 p.m. ......................89
xiii 

Figure 68. Early-age stress-to-strength ratio as a function of time of placement. .....................................89

Figure 69. Transverse cracking as a function of time of placement. .........................................................90

Figure 70. International Roughness Index (IRI) and serviceability as a function of time of placement. ..90

Figure 71. Early-age analysis results for 4.5-m joint spacing....................................................................92

Figure 72. Early-age analysis results for 7.6-m joint spacing.....................................................................92

Figure 73. Predicted faulting for 4.5-m and 7.6-m joint spacing alternatives with no dowels. .................93

Figure 74. Predicted faulting for 4.5-m and 7.6-m joint spacing alternatives with dowels. ......................93

Figure 75. Change in crack spacing with time for summer and winter placements. .................................94

Figure 76. Representation of PCCP temperatures in the early age and at the lowest seasonal air 

temperature. .........................................................................................................................................95

Figure 77. Crack spacing distribution for pavements constructed during summer and winter..................95

Figure 78. Illustration of differences in cracking patterns for pavements A and B. ..................................96

Figure 79. Illustration of difference in volumetric changes with temperature for concretes with 

different CTE.......................................................................................................................................97

Figure 80. Average crack spacing after 1 year for aggregates with different CTE....................................98

Figure 81. Crack spacing distribution after 1 year for the siliceous river gravel and 

limestone strategies..............................................................................................................................98

Figure 82. Project type selection screen for HIPERPAV II analysis.........................................................99

Figure 83. Project information screen for HIPERPAV II analysis. .........................................................100

Figure 84. Geography screen for HIPERPAV II analysis........................................................................101

Figure 85. Monthly weather data screen for HIPERPAV II analysis. .....................................................102

Figure 86. Strategy information screen for HIPERPAV II analysis. .......................................................103

Figure 87. Geometry screen.....................................................................................................................104

Figure 88. Schematic of the geometry input in HIPERPAV II................................................................104

Figure 89. Dowel input screen. ................................................................................................................105

Figure 90. Slab support input screen........................................................................................................106

Figure 91. Available subbase types or subgrade conditions. ...................................................................106

Figure 92. Cement input screen. ..............................................................................................................107
xiv 

Figure 93. Available cement types in HIPERPAV II. .............................................................................108

Figure 94. Heat of hydration help screen in HIPERPAV II.....................................................................108

Figure 95. PCC mix input screen.............................................................................................................109

Figure 96. Available coarse aggregate types in HIPERPAV II. ..............................................................109

Figure 97. Available admixture types in HIPERPAV II..........................................................................110

Figure 98. Fly ash class drop-down menu. ..............................................................................................110

Figure 99. PCC properties screen for early-age JPCP analysis................................................................111

Figure 100. Strength type drop-down menu. ...........................................................................................111

Figure 101. Help icon under PCC properties screen................................................................................112

Figure 102. Maturity data input screen. ...................................................................................................113

Figure 103. Construction screen. .............................................................................................................114

Figure 104. Drop-down menus and help screens under construction inputs. ..........................................115

Figure 105. Environment screen. .............................................................................................................116

Figure 106. Drop-down menu for selection of climatic input screen to display......................................116

Figure 107. Time-temperature distribution modified with the point feature. ..........................................117

Figure 108. Time-temperature distribution modified with the high-low feature. ....................................117

Figure 109. Time-temperature distribution modified subjected to a cold front. ......................................118

Figure 110. Analysis screen for early-age JPCP......................................................................................118

Figure 111. HIPERPAV II early-age analysis showing poor performance. ............................................120

Figure 112. Evaporation rate analysis for early-age JPCP analysis.........................................................121

Figure 113. Dowel analysis screen for early-age JPCP. ..........................................................................122

Figure 114. Strategy type pulldown menu. ..............................................................................................123

Figure 115. Strategy information for long-term JPCP analysis. ..............................................................123

Figure 116. Performance criteria screen for long-term JPCP analysis. ...................................................125

Figure 117. Load-transfer design for long-term JPCP analysis. ..............................................................126

Figure 118. General traffic loading screen for long-term JPCP analysis.................................................127
xv 

Figure 119. Single axle load screen for long-term JPCP analysis. ..........................................................128

Figure 120. Traffic loading growth rate screen for long-term JPCP analysis..........................................129

Figure 121. Analysis screen for long-term JPCP.....................................................................................130

Figure 122. Drop-down menu for distress to plot....................................................................................130

Figure 123. Plot method drop-down menu. .............................................................................................130

Figure 124. Analysis results for the siliceous river gravel strategy. .......................................................134

Figure 125. Analysis screen for limestone strategy. ................................................................................135

Figure 126. Selection of early-age strategies to compare. .......................................................................137

Figure 127. Long-term strategy transverse cracking results. ...................................................................137

Figure 128. Geometry screen for early-age CRCP analysis. ...................................................................139

Figure 129. Steel design screen for early-age CRCP analysis. ................................................................140

Figure 130. Early-age construction screen for early-age CRCP analysis. ...............................................141

Figure 131. Post 72-hour air temperatures screen for early-age CRCP analysis. ....................................142

Figure 132. Analysis screen for early-age CRCP. ...................................................................................143

Figure 133. Drop-down menu for time period to plot..............................................................................143

Figure 134. Help icon under CRCP analysis screen. ...............................................................................144

Figure 135. CRCP analysis with poor cracking characteristics. ..............................................................145

Figure 136. HIPERPAV II report screen. ................................................................................................146

Figure 137. Tools drop-down menu in HIPERPAV II. ............................................................................146

Figure 138. Mix constituents input screen in COMET............................................................................147

Figure 139. Factor limits input screen in COMET. .................................................................................148

Figure 140. Create trial batches command button in level 1 outputs.......................................................148

Figure 141. Trial batches in kg/m3, gravimetric form..............................................................................149

Figure 142. Predicted responses for each trial batch................................................................................150

Figure 143. Lab results screen. ................................................................................................................151

Figure 144. Desirability function for 28-day strength. ............................................................................151
xvi 

Figure 145. Level 2 outputs—command to optimize mixes. ...................................................................152

Figure 146. Optimum mixes sorted by desirability in volumetric form...................................................153

Figure 147. Optimum mixtures in terms of optimization factors..............................................................154

Figure 148. Response predictions for optimum mixtures. .......................................................................155

Figure 149. Individual response desirabilities for optimum mixtures. ....................................................155

Figure 150. Report view for printing purposes. .......................................................................................156
xvii 

LIST OF TABLES 

Table 1. Inputs for 11 a.m. and 7 p.m. times of placement strategies......................................................132

Table 2. Long-term inputs for aggregate selection sample scenario........................................................136

1 

CHAPTER 1. INTRODUCTION 

The HIPERPAV® II system was developed as a tool for predicting the early-age behavior of both 

Jointed Plain Concrete Pavements (JPCP) and Continuously Reinforced Concrete Pavements (CRCP). In 

addition, the effect of early-age behavior factors on JPCP long-term performance has been addressed. It 

is expected that the above predictive capabilities will help designers, contractors, and concrete suppliers 

identify factors that can contribute to achieving good performing pavements. Similarly, it is expected that 

factors that could potentially put the pavement’s long-term performance at risk also can be identified. 

It is important to recognize the numerous factors affecting the performance of a concrete 

pavement, and furthermore, when and how these factors come into play during the various stages of a 

pavement project. For example, planners may use HIPERPAV II to develop quality control specifications 

for projects based on the available materials and climatic conditions in the region of construction. For 

designers, HIPERPAV II may be used to optimize pavement designs so that an improved long-term 

pavement performance is achieved. For contractors, HIPERPAV II may be used to prevent expensive 

pavement repairs. Higher potentials of cracking due to unexpected changes in the weather can be 

predicted and avoided. Using HIPERPAV II, the impact of these changes on the pavement is quantified, 

and an alternative construction time or method can be developed to reduce or altogether prevent pavement 

damage. Suppliers may use HIPERPAV II to assess the performance of a given mix design under various 

climatic conditions. Finally, HIPERPAV II may be used as a forensic analysis tool for pavements. For 

example, engineers can better pinpoint the reasons behind pavement damage and/or poor pavement 

performance. 

With these considerations in mind, this document aims to provide theoretical concepts on earlyage behavior and long-term pavement performance, providing a basis for understanding the numerous 

models in HIPERPAV II. Ultimately, understanding the above concepts will help guideline users select 

from the wide range of design and construction alternatives available. Finally, a user’s guide for the 

HIPERPAV II system is presented at the end of this document. 

1.1 BACKGROUND 

The original HIPERPAV I system provided design and construction guidelines for JPCP. This 

set of guidelines provided recommendations for selecting primary inputs that influence the early-age 

behavior of JPCP.(1) In this document, the guidelines are extended to cover the design and construction of 

CRCP. In addition, the JPCP guidelines are extended to consider the inputs of various early-age 

parameters on long-term performance. 

If well designed and constructed, CRCP is one of the best alternatives for heavily trafficked 

roads. This is especially true when minimizing user delays due to maintenance, providing long-lasting 

smoothness, and minimizing user costs are important considerations. Identifying factors that influence 

the early-age behavior of CRCP will therefore provide the basis for developing adequate guidelines to 

improve current design and construction practices. 

Several investigations have addressed the importance of early-age behavior on long-term 

performance of concrete pavements.(1,2,3) Most of the factors that influence the early-age behavior of 

concrete pavements can be classified into four different categories: pavement design, materials and mix 

design, environmental, and construction operations. Based on these factors, initial conditions have been 
2 

identified that are known to influence the performance of the pavement in the long term. Such initial 

conditions or early-age indicators of long-term performance include joint/crack opening, built-in curling, 

and surface delamination due to moisture loss. This document identifies the primary early-age indicators 

influencing the long-term performance of the pavement. To understand their progression with time, the 

effects of traffic and long-term environmental factors are also discussed. 

1.2 OBJECTIVES 

The primary objective of this volume is to serve as a stand-alone document covering a 

comprehensive set of guidelines useful in the design and construction of both JPCP and CRCP concrete 

pavements. Good design and construction practices not only will help prevent immediate (early-age) 

problems from occurring, but also may improve performance in the long term. To accomplish this, this 

document will cover guidelines on the following topics: 

1. Early-age behavior of JPCP and CRCP pavements. 

2. Early-age distresses that may result from poor design or construction practices. 

3. Early-age indicators that can influence long-term pavement performance (e.g., joint opening, 

crack spacing). 

4. Long-term pavement distresses that relate to early-age factors (e.g., cracking, punchouts, 

faulting). 

In addition, this document also provides sample case studies that illustrate the proper use of 

HIPERPAV II to optimize concrete pavement behavior and contains a user’s manual. 

1.3 SCOPE AND FORMAT 

Chapter 2 presents a brief description of early-age concrete pavement behavior. “Early age” in 

these guidelines is defined as the first 72 hours after pavement construction for both JPCP and CRCP. 

According to experience, the potential for damage to the pavement structure due to excessive thermal and 

moisture related stresses is significant during this time. However, in the case of CRCP, the cracking 

behavior continues to change until approximately 1 year after construction. After 1 year, cracking 

commonly remains constant. HIPERPAV II predicts the cracking behavior of CRCP during the early age 

and also during the early life (up to 1 year) to realistically assess the behavior of CRCP inservice. 

Primary early-age indicators influencing long-term pavement performance for JPCP and CRCP are also 

discussed in this section. 

In chapter 3, early-age concrete pavement distresses such as plastic shrinkage cracking and 

thermal shock are discussed. Considerations are made for both JPCP and CRCP. 

Chapter 4 presents a mechanistic approach to the impact of early-age behavior on long-term 

performance. The influence of early-age indicators on each individual distress type will be discussed. 

Primary distress types associated with early-age pavement behavior addressed include faulting, spalling, 

transverse cracking, corner cracking, spalling, and punchouts. 

Chapter 5 provides recommendations and guidelines for inputs selected from five unique 

categories: pavement design, materials and mix design, environment, construction, and traffic inputs. 
3 

Sample case studies are presented in chapter 6, with design and construction scenarios to 

illustrate the proper use of the guidelines. The guidelines have been developed with two possible 

scenarios in consideration: a proactive scenario, and a post-mortem scenario. 

The proactive scenario is one that may occur anytime during the planning, design, or construction 

stages of a project. Under this scenario, the guidelines user may refer directly to chapter 5—HIPERPAV 

II Input Parameters—for the proper selection of HIPERPAV II inputs under the five categories of 

pavement design, materials and mix design, environment, construction, and traffic. Because these 

guidelines provide only general guidance with the selection of the input parameters in these categories, it 

is the user’s responsibility to use engineering judgment in the final selection of the inputs. 

For the case of the post-mortem scenario, the guidelines user may be experiencing a particular 

problem either occurring in the early age or during the long term. For this particular case, the user may 

refer to chapter 3, Early-Age Pavement Distresses, or chapter 4, Impact of Early-Age Behavior on LongTerm Performance, according to the nature and timeframe of the specific problem. 

Under both scenarios, the user may refer to chapter 2, Early-Age Pavement Behavior, for a 

detailed understanding of the mechanisms occurring during the early age that influence the performance 

of the pavement in the long term. 

Finally, chapter 7 is a user’s guide for the HIPERPAV II system. 

5 

CHAPTER 2. EARLY-AGE PAVEMENT BEHAVIOR 

2.1 GENERAL 

The behavior of concrete pavements at early ages is influenced by a number of factors including, 

but not limited to: 

• Generated heat from hydration of the cement. 

• Climatic conditions such as air temperature, solar radiation, relative humidity of the air, and 

windspeed. 

• Concrete temperature and subbase temperature during placement. 

• The concrete coefficient of thermal expansion (CTE). 

• Slab-subbase interface restraint. 

• Concrete shrinkage as a result of the drying process. 

• Curling and warping of the concrete slab as a result of temperature gradients. 

• Creep/relaxation phenomena. 

• Construction procedures. 

During the first hours after construction, the interactions of these factors result in volume changes 

in the concrete, primarily due to changes in temperature and moisture. During the hardening state, 

stresses in the concrete start to buildup due, in part, to slab curling and warping and restraint to axial 

movements at the slab-subbase interface. As concrete is weak in tension, undesirable situations may 

occur if the stresses in the concrete exceed the developing strength. 

In this context, early age is understood as the first 72 hours after pavement placement. 

Experience demonstrates that significant stresses in the pavement develop during this curing period. 

These stresses may lead to undesirable situations if not properly controlled. 

2.1.1 Temperature and Moisture Changes 

The following sections describe the various factors that influence the temperature and moisture 

state of early-age concrete. 

2.1.1.1 Heat of Hydration 

A number of properties of concrete are governed by the heat of hydration of the cementitious 

materials. These properties include concrete set time, strength development, and modulus of elasticity 

development. In addition, the heat of hydration contributes to the temperature increase in the concrete 

during the first hours after placement. 

The combination of cementitious materials and water results in a variety of chemical reactions in 

which hydration products are formed. The hydration of the cementitious materials is exothermic, and the 

degree of hydration is related to the amount of heat liberated at any point during the hydration stage. The 
6 

rate of hydration and total heat liberated during hydration depends on factors such as the type of cement, 

admixtures, water-to-cementitious materials ratio (w/cm), fineness of the cement, and curing temperature. 

2.1.1.2 Concrete Temperature 

In the early ages, concrete temperature is a function of the heat of hydration and climatic 

conditions. The heat generated due to hydration results in a temperature rise in the concrete as a function 

of the thermal conductivity and specific heat of the paste and aggregate. On the other hand, climatic 

conditions such as air temperature, solar radiation, cloud cover, and convection due to windspeed affect 

the amount of heat lost or gained through the surface of the pavement. This heat loss or gain is 

transported through the depth of the slab, as a function of the concrete thermal conductivity and specific 

heat. Heat conduction to or from the subbase also affects the temperature of the concrete. 

An intrinsic relationship exists between heat of hydration and concrete temperature. Because the 

heat of hydration has a direct correlation with the development of mechanical properties such as strength 

and modulus of elasticity, the temperature at which the concrete is cured will affect its mechanical 

properties. 

2.1.1.3 Moisture in Concrete 

Moisture in the concrete may be classified into two types. The first type is structural water, 

chemically bound within the cement paste. The second type is water contained in the pore structure. The 

sum of these portions equals the total water content in the paste. In addition to temperature development, 

the moisture state in the pore structure of hydrating concrete is another important factor affecting its 

early-age behavior. It has been recognized that the level of moisture at which a concrete structure is 

cured can have a significant effect on its strength, and also on the stress development due to shrinkage. 

The moisture profile in a pavement structure is a function of climatic conditions such as relative 

humidity, temperature, and precipitation. The moisture state of the underlying subbase also affects this 

moisture profile. In addition to the external moisture conditions at which the pavement structure is 

exposed, the moisture gradients in the pavement are also a function of the thermodynamic equilibrium 

conditions of moisture flow and the random geometrical nature of the pores in the concrete structure. In 

general, differences of energy due to capillary forces, gravity, and thermal gradients are the primary 

factors governing the moisture transport in concrete. The flow of moisture is also a function of the 

concrete moisture diffusivity and the characteristics of the porous media.(4) 

2.1.2 Development of Concrete Properties 

This section describes the development of various early-age concrete properties. 

2.1.2.1 Concrete Set 

Concrete set is defined as the transition of concrete from a plastic to a solid state. Concrete set 

also marks the start of development of significant mechanical properties. It also is common to associate 

the set time with the moment where the stresses in the slab begin to develop due to volumetric changes 

coupled with various restraints. 
7 

2.1.2.2 Strength and Modulus of Elasticity Development 

Tensile strength development in concrete begins to increase after the concrete sets. It develops 

primarily as a function of the water-to-cement (w/c) ratio, cement, admixtures, and aggregate 

characteristics and content. It is also a function of the energy of compaction (consolidation), the curing 

temperature, and moisture state. The strength of the concrete depends on the strength of the cement paste, 

the strength of the aggregates, and the bond strength of the cement/aggregate interface. The rate of 

strength development will be a function of the cement properties such as the cement fineness, cement 

compounds, and admixtures used. 

Cements with a higher fineness commonly will hydrate faster, developing a high early strength, 

although the strength development at later ages may be lower as compared to coarser cements. 

Furthermore, it has been observed that fine ground cements are associated with durability problems.(5) A 

similar effect on the strength development occurs when the concrete is cured at high temperatures. A 

rapid strength increase is observed at early ages, and a less steep strength increase is noted with the longterm strength. 

The effect of moisture on concrete strength also should be emphasized. In concrete pavements, 

pronounced moisture profiles may occur as a consequence of climatic conditions. It has been observed 

that whenever the internal relative humidity in the concrete drops below 80 percent, the development of 

strength can be significantly affected.(6) Similar to strength, the hardening process of concrete also 

contributes to its stiffness or modulus of elasticity. The concrete modulus of elasticity is directly related 

to the concrete strength, and also depends on the type of aggregates and its volume in the concrete mix. 

2.1.3 Development of Stresses 

Stresses in concrete pavements develop due to a number of factors. The following sections 

discuss some of these. 

2.1.3.1 Axial Expansion and Contraction 

As the temperature changes after set, the concrete tends to expand or contract as a function of its 

CTE. The concrete CTE is a function of the CTE of the paste and the CTE of the aggregates. Depending 

on the concrete-making materials and specifically on the type of coarse aggregate selected, the concrete 

CTE may be higher or lower. Typically, calcareous aggregates such as limestone and dolomite have a 

low CTE (4 to 9 × 10-6 m/m/oC) while siliceous aggregates, such as quartzite, possess a high CTE (10 to 

12.5 × 10-6 m/m/oC). Also, because the CTE of the hardened cement paste is greater than that of the 

aggregate, as the percentage of aggregate increases, the overall concrete CTE decreases. CTE has been 

found to be one of the most influential factors on the performance of concrete pavements. Stresses in the 

concrete also develop due to restraints imposed at the slab-subbase interface that resist the expansion and 

contraction of the slab. Stresses develop in the concrete due to this restraint coupled with the temperature 

changes from day to night. Expansive movements will lead to compressive stresses, while contractive 

movements will lead to tensile stresses. 

2.1.3.2 Plastic Shrinkage 

As the name implies, plastic shrinkage occurs in the plastic state of concrete, before it sets. 

Plastic shrinkage is a function of the evaporation of water from the surface of the concrete. Evaporation 

is a function of air temperature, windspeed, ambient relative humidity, concrete temperature, and many 
8 

other factors. If the water at the surface evaporates faster than the water that migrates from the interior of 

the slab, plastic shrinkage can occur. Plastic shrinkage can also occur at the bottom of the slab by suction 

due to a dry subbase.(7) Plastic shrinkage commonly takes the form of random cracks at the surface of the 

concrete. 

2.1.3.3 Autogenous Shrinkage 

Autogenous shrinkage is related to the reduction in volume of the cement paste as a result of selfdesiccation. Self-desiccation is a process where physical and chemical changes in the cement 

components during hydration lead to drying of the capillary pores in the concrete. This reduction in 

volume is significant after initial setting and is more pronounced in the case of high-strength concrete 

where low w/c ratios are used. Autogenous shrinkage has been observed to be less significant for high 

w/c ratios.(8) 

Autogenous shrinkage is not associated with moisture transport, temperature changes, or external 

restraints. Shrinkage reducing admixtures are available to minimize autogenous shrinkage. However, 

autogenous shrinkage can also be minimized or avoided by maintaining water available during the cement 

hydration. This can be accomplished by water curing or by including saturated porous aggregate in the 

mix (commonly termed internal curing).(8) When enough water is available during hydration, selfdesiccation is avoided, and some minor swelling of the concrete may occur instead.(9)

2.1.3.4 Drying Shrinkage 

Drying shrinkage of concrete occurs due to drying when concrete is exposed to unsaturated air. 

The normal wetting and drying cycles to which the concrete is subjected lead to changes in the moisture 

state of the concrete. Although some of the water movement may be replaced by subsequent wetting 

periods, some of the water lost to the environment is irreversible and leads to permanent concrete 

shrinkage. Drying shrinkage is a function of a number of factors, including the w/c ratio, cement type, 

cement content, admixtures used, type and amount of aggregates, and climatic conditions. 

2.1.3.5 Curling and Warping 

Temperature and moisture transport in the concrete result in gradients that can lead to curling and 

warping movements and stresses. The concrete slab will curl up or down depending on whether the top 

of the slab is cooler or warmer than the bottom. If the top of the slab is cooler than the bottom, the upper 

surface will tend to contract, and the bottom will tend to expand, causing the slab to curl up. A downward 

curling usually is observed if the opposite temperature differential occurs. Due to its exposure to the 

environment, the top of the slab typically experiences higher drying shrinkage than the bottom. This can 

cause an upward curvature of the slab, commonly known as warping. Warping has been observed to 

change as a function of the climate, including the relative humidity and rainfall. Slab curling and warping 

are, in turn, restrained by the weight of the slab as well as subbase restraints. Compressive and tensile 

stresses are generated in the pavement as a function of this restrained movement. 

2.1.3.6 Creep/Relaxation 

It has been observed that creep and relaxation effects can be significant during the early age of 

concrete.(10) When concrete is subjected to a constant load, both an instantaneous and a delayed elastic 

strain occur. Strain due to plastic deformation of the concrete develops and increases during the loading 

period. If the load is removed, the elastic strain is totally recovered, while the strain due to plastic 
9 

deformation is not. This viscous behavior is commonly known as creep. Conversely, when concrete is 

subjected to a constant strain level, relaxation of stresses occurs.

During the early age, concrete behaves more like a viscoelastic material than it does later in its 

hardened state, when its behavior is more purely elastic. During this early-age period, concrete is more 

susceptible to creep and relaxation effects. Because most of the axial, shrinkage, and curling movements 

in the pavement are restrained by external factors (such as the slab weight and subbase restraints), the 

pavement is constantly subjected to tensile and compressive strains. The corresponding level of stress 

that develops is a function of the creep-relaxation characteristics of the concrete. 

Figures 1 and 2 illustrate the typical relaxation effects in concrete as a consequence of 

temperature loading. After the concrete is placed, the concrete temperature increases due to the heat of 

hydration (figure 1). Immediately after the concrete sets, strength begins to develop. As the concrete is 

restrained to move in the axial direction, the concrete tries to expand due to the temperature increase, and 

compressive stresses develop (figure 2). Because of the creep characteristics of the concrete at such an 

early age, the compressive stresses are relaxed significantly. After the maximum temperature is reached 

and the concrete starts a cooling period, the concrete begins to contract. Due to the continued relaxation, 

the concrete is subjected to tensile stresses even before it cools down to the set temperature at which the 

compressive stresses initially started. Eventually, as the concrete keeps contracting, increased tensile 

stresses are generated. When the concrete stresses exceed the tensile strength of the concrete, cracks 

form. The creep and relaxation properties of concrete are a function of a number of factors, including the 

moisture state, temperature, concrete properties, stress level, duration of load, and concrete age.(10) 

Average

temperature 

in the element

Temperature

Maximum

temperature

Time

PCC set

Average

temperature 

in the element

Temperature

Maximum

temperature

Time

PCC set

Figure 1. Conceptual representation of temperature development in a concrete element with time. 
10 

Average

stress

Tensile

strength

Time

Compression

Tension

Stress

PCC

set

Crack

formation

Actual stress with 

relaxation effect

Theoretical stress with

no relaxation effect

Average

stress

Tensile

strength

Time

Compression

Tension

Stress

PCC

set

Crack

formation

Actual stress with 

relaxation effect

Theoretical stress with

no relaxation effect

Figure 2. Conceptual effect of creep/relaxation on concrete stresses.(11)

2.1.4 Thermal Cracking 

The combination of axial and curling thermal stresses commonly leads to the development of 

significant compressive and tensile stresses. Because the concrete is weaker in tension than in 

compression, any condition leading to a decrease in concrete temperature, thermal gradients in the slab, 

and/or the continued drying shrinkage originated from moisture changes may result in thermal cracking 

whenever the stresses that develop exceed the tensile strength of the concrete. 

2.2 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE OF JPCP 

The size of the joint opening in JPCP is one of the primary early-age indicators of the pavement’s 

long-term performance. This opening controls the load transfer efficiency across the joint, which controls 

how well the JPCP will perform over time. JPCP can either have doweled or nondoweled joints. In this 

section, the physical mechanisms that influence joint movement are described. In addition, the influence 

of joint opening on pavement distresses is discussed. 

2.2.1 Physical Mechanisms Governing Joint Opening at Early Ages 

The joint opening at early ages is primarily controlled by the effects of temperature and moisture 

changes on pavement and subbase properties such as concrete CTE, drying shrinkage, and subbase 

restraint. Before the concrete’s final set, a common assumption is that the pavement is free of stress and 

strain. After this time, stress develops in the pavement due to phenomena such as climatic conditions, 

hydration, creep, and shrinkage. 

As an example, if the pavement is subjected to an increase in temperature (+∆T), the pavement 

will expand about its centerline, and the joint will close. During a decrease in temperature (–∆T), the 

pavement will contract about its centerline, and the joint will open (see figure 3). 
11 

Centerline

Joint opens (-∆T)

Contraction

Figure 3. Schematic of joint opening due to temperature drop (–∆T). 

It has been observed experimentally that a change in temperature is the most influential parameter 

affecting joint opening. Joint opening varies with the daily temperature cycles due to changes in the 

pavement’s thermal conditions.(12) CTE, drying shrinkage, and pavement length also affect the joint 

opening. To control the joint opening to acceptable levels, proper curing of the pavement at the time of 

placement is of paramount importance. If the concrete’s temperature differential can be minimized, the 

size of the joint opening will decrease as a result. Likewise, drying shrinkage should also be minimized if 

the joint opening is to stay tight. This can also be accomplished with adequate curing methods. 

2.2.2 Effect of Joint Opening on Load Transfer Efficiency—JPCP without Dowels 

In JPCP without dowels at the joints, the size of the joint opening governs the load transfer 

efficiency across the joint (see figure 4). The aggregate interlock transfers the load, and its efficiency is a 

function of factors such as aggregate type, aggregate size, angularity, and abrasion characteristics.(13) 

However, if the joint opening is too wide (0.6 millimeters (mm) or greater), the aggregate cannot provide 

load transfer.(14) In addition, because of the wide opening, water can infiltrate the subbase from the 

surface of the pavement. The water will infiltrate faster as the joint opening increases. The size of the 

joint opening also determines how quickly incompressibles can fill the joint over time. Incompressibles 

apply pressure on the pavement edges and can cause spalling, as described in section 2.2.4. 

Saturated subbase

Water and incompressibles

Joint opening

Aggregate 

interlock

Joint width

Joint depth

Saturated subbase

Water and incompressibles

Joint opening

Aggregate 

interlock

Joint width

Joint depth

Figure 4. Schematic of joint in JPCP without dowels. 

The loss of load transfer across the joint can result in the development of significant deflections, 

particularly for the case of granular subbases, as shown in figure 5. This eventually can lead to faulting 

and transverse cracks, so it is desired that the pavement maintain good load transfer efficiency. This 

phenomenon will be discussed in more detail in section 2.2.4. 
12 

Saturated 

subbase

Deflected slab

Figure 5. Schematic of JPCP after loss of aggregate interlock/load transfer at the joint.

2.2.3 Effect of Joint Opening on Load Transfer Efficiency—JPCP with Dowels 

For JPCP with dowels across the joint, the dowels act to partially restrain vertical movement. As 

figure 6 illustrates, the adjoining slabs deflect a similar amount. This minimizes faulting, while still 

allowing horizontal movement due to temperature fluctuations. The size of the joint opening does not 

significantly affect the load transfer efficiency component due to the dowels. 

Deflected slabs

Dowel bar

Saturated subbase

Figure 6. Schematic of doweled joint in JPCP. 

2.2.4 Distresses Influenced by Joint Opening—JPCP without Dowels 

As described in the previous sections, the size of the joint opening can impact significantly the 

behavior of the pavement in the long term. Three possible pavement distresses that can result due to 

adverse behavior are spalling, faulting, and transverse cracking. 

Spalling. Spalling is one of the pavement distresses that can occur at a concrete pavement joint. 

Incompressibles that enter the joint exert pressure on the pavement edges. This pressure can induce 

significant stresses in the concrete that can eventually cause the concrete to spall. This form of distress 

may be delayed or prevented if the joint opening is tight enough to prevent infilling of incompressibles. 

More details on spalling are provided in sections 4.5 and 4.6. 

Faulting. When aggregate interlock at the joint does not provide adequate load transfer, the pavement 

profile will not be continuous (section 2.2.1). Faulting can occur due to this mismatch in slab deflections 

at the joint. A larger joint opening can also increase the amount of water infiltration into the joint. 

Faulting can initiate when aggregate interlock at the joint is no longer effective. More details on faulting 

are provided in sections 4.1 and 4.2. 

Transverse Cracking. Transverse cracks can form in JPCP due to a number of different mechanisms. 

The two mechanisms discussed here are both the result of a large joint opening. The first form of 
13 

transverse cracking is termed top-down cracking; it is caused by the erosion of the subbase support. 

Severe erosion of the granular subbase material from under the leading edge of the pavement can cause 

tensile stresses to form at the pavement surface. This extreme loss of support can cause a top-down 

transverse crack to form. For a nonerodable stabilized subbase, transverse cracking can still occur, but 

the mechanism is different. Incompressibles can become trapped beneath the pavement and the subbase. 

This leads to a slab lift-up, and a bottom-up transverse crack can result. Both bottom-up and top-down 

transverse cracking can be avoided or delayed if water seepage into the pavement joint is prevented. This 

is possible if a tight joint opening can be maintained. Transverse cracking is discussed in greater detail in 

section 4.3. 

2.2.5 Distresses Influenced by Joint Opening—JPCP with Dowels 

In doweled JPCP, pavement distresses are related predominately to the bearing stress placed on 

the concrete at the dowel-concrete interface. If this pressure is too great, spalling of the overlying 

concrete is possible. Likewise, faulting is possible if the bearing stress is excessive. The dowels will lose 

their ability to transfer load if their bearing stress causes the concrete around them to fail. Over time, 

faulting will be apparent. Yet, if the bearing stress is kept below the crushing strength of the concrete, 

faulting can be maintained at an acceptable level.(15) Dowel looseness also is possible if the dowelconcrete stress is very high. The concrete near the dowel can crush, and voids can develop underneath as 

the crushed concrete particles are removed. For more detail on dowel looseness, refer to section 5.1.7. 

2.3 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE OF CRCP 

As its name implies, CRCP refers to concrete pavement constructed with no transverse 

contraction joints, and is reinforced with steel. For this type of pavement, concrete is allowed to crack 

randomly as a consequence of volume changes resulting from temperature and moisture variations that 

are restrained by steel and subbase friction. 

Concrete and steel tend to contract and expand with changes in temperature. Because the CTE of 

steel and concrete are usually different, the expansion and contraction movements are not uniform, and 

stresses can develop in both elements. Concrete drying shrinkage, slab curling and warping, and subbase 

restraint each contribute uniquely to stress development. Since concrete is weak in tension, whenever the 

stresses that develop are higher than the tensile strength of the concrete, transverse cracks form to relieve 

the stresses. Because the steel has a high yield strength, it keeps cracks together. Keeping the cracks 

tight is essential in maintaining load transfer through aggregate interlock, and to avoid water infiltration 

and intrusion of incompressibles through the cracks. Subsequent drops in temperature and loss of 

moisture in the concrete can reduce the transverse crack spacing further. Later in the life of the pavement, 

externally induced stresses due to wheel loads and seasonal changes in climatic conditions can reduce the 

initial crack spacing even further. It has been observed that the crack spacing decreases rapidly during the 

early age of the pavement, then remains fairly constant from the initial year until pavement wearout, as 

illustrated in figure 7.(16) 
14 

Initial 

Phase

Mean Crack Spacing

Fatigue

Phase Stable Phase

Time

Initial 

Phase

Mean Crack Spacing

Fatigue

Phase Stable Phase

Time

Figure 7. Conceptual reduction in mean crack spacing over time.(16)

The crack spacing typically is greater near the ends of the pavement than at the central section. 

This is because the pavement is more restrained to movement at the center of the slab than at the ends. 

Therefore, most of the longitudinal movement due to volume changes occurs at the ends of the slab, and 

higher stresses are generated at the central section of the pavement. 

Previous experience has shown that primary early-age pavement indicators of performance on 

CRCP include crack spacing, crack width, and steel stress. The following sections describe these 

behavioral indicators in more detail. 

2.3.1 Crack Spacing 

CRCP slabs usually distribute traffic loads in both the longitudinal and transverse directions. 

However, in the case of short crack spacings, the slab acts more as a beam, with its longer dimension on 

the transverse direction. As a result, the load is distributed primarily in the transverse direction, and 

significant transverse tensile stresses may develop. Due to this condition, longitudinal cracks may form 

as a function of the magnitude of the stresses, tensile strength, fatigue characteristics of the concrete, and 

cumulative load applications. The longitudinal cracks lead to a distress condition that is commonly 

known as a punchout. Punchouts are a typical distress manifestation in CRCP where a block of the 

concrete slab is separated from the rest of the pavement by cracks in the transverse and longitudinal 

directions. The severity and progression of punchout distresses is a function of the traffic loads, support 

conditions, and load transfer between cracks. On the other hand, larger crack spacings commonly result 

in wider cracks that may lead to spalling problems. 

McCullough et al. demonstrated that the crack spacing could be properly controlled to fall within 

certain limits to minimize such undesirable conditions. He proposed a crack spacing of 1.7 to 2.4 meters 

(m) for this purpose.(2) The American Association of State Highway and Transportation Officials 

(AASHTO) guidelines later recommended a similar crack spacing of 1.1 to 2.4 m,(17) although, in some 

instances, crack spacings of less than 0.6 m have performed well under very good soil-support 

conditions.(18) Crack spacing in CRCP is also affected due to the variability of materials and construction 

procedures. Therefore, it is a recommended practice to evaluate crack spacing in terms of its average 

value as well as in terms of its distribution. For a given crack spacing distribution, the percentage of 

crack spacings that do not fall within the recommended range of 1.1 to 2.4 m will lead more likely to 

distress during the life of the pavement. 
15 

2.3.2 Crack Width 

Crack widths affect CRCP performance in several ways. For example, excessive crack widths 

may lead to undesirable conditions (such as infiltration of water) that later result in corrosion of the 

reinforcing steel. Incompressibles can also enter the cracks. Because the pavement is subject to 

contraction and expansion movements as well as deflections due to traffic loadings, this can lead to 

excessive stresses at the cracks that eventually lead to spalling. In addition, for wider cracks, there is less 

contact between the surfaces of the cracks, resulting in poor aggregate interlock. This results in increased 

slab deflections and stresses. Higher stresses in the concrete, in turn, lead to spalling, faulting, additional 

cracking, and punchouts. 

Recent investigations have found that cracks that form within the first few days after pavement 

construction tend to be wider than cracks that form later during the life of the pavement.(16,19) One 

possible explanation for this behavior is due to the bond strength development at the concrete-steel 

interface. At earlier ages, the bond strength is weaker than at a later age. Therefore, the bond strength 

does not restrain the movement of the crack at earlier ages as it does later when this bond is stronger, and 

the restraint to movement is higher. This phenomenon results in tighter cracks. Furthermore, concrete 

drying shrinkage also increases with time after placement. Because drying shrinkage is one of the factors 

that govern the contraction of the concrete, the increase of drying shrinkage with time will also affect 

crack width. It has been observed that cracks that develop during the first few days are more affected by 

the remaining drying shrinkage than cracks that occur later when the remaining drying shrinkage is not as 

large. 

A crack width of 0.6 mm has been found to be effective in reducing water percolation.(2) The 

AASHTO guidelines limit the crack width to 1 mm to avoid spalling and to limit water penetration.(17) 

For temperatures below freezing, crack width is not as much of a consideration, because frozen conditions 

do not permit the penetration of water.(16) A strong correlation between crack spacing and crack width has 

been found in some references.(2) It is believed that this correlation is due primarily to the fact that many 

of the mechanisms that influence crack spacing also influence crack width.(2,19) 

2.3.3 Steel Stress 

The level of stress at which the concrete and the steel are subjected in a CRCP will influence its 

performance in the long term. As stated before, due to volume changes in the concrete, the reinforcement 

acts as a restraining system to keep cracks together. Consequently, significant stresses develop in the 

steel at the crack locations. The design of the steel reinforcement must consider the possible steel fracture 

and/or excessive plastic deformation. Usually, the stress at which the steel is subjected is limited to a 

reasonable percentage of the ultimate tensile strength to avoid steel fracture, and allowing only a small 

amount of plastic deformation.(17,20)

2.3.4 Factors Affecting Crack Spacing, Crack Width, and Steel Stress 

It has been shown that crack spacing, crack width, and steel stress on CRCP are a function of the 

concrete tensile strength and the level of stresses that result due to the restraint to volume changes. 

Therefore, any factor affecting the concrete tensile strength, the pavement restraint, or factors contributing 

to volume changes will affect the cracking characteristics of CRCP, and therefore can influence its longterm performance. 
16 

Primary factors known to affect crack spacing and crack width in the early age include: 

• Coarse aggregate type (see section 5.2.1). 

• Steel reinforcement (see section 5.1.8). 

• Placement temperature (see section 5.4.3). 

• Time of the day of placement (see section 5.4.2). 

• Curing procedures (see section 5.4.1). 

• Slab thickness (see section 5.1.2). 

• Subbase type (see section 5.1.6). 

2.4 EARLY-AGE INDICATORS OF LONG-TERM PERFORMANCE COMMON TO JPCP 

AND CRCP 

The early-age behavior of JPCP and CRCP is different in many respects. However, because both 

pavement types are made with portland cement concrete (PCC), they share some mechanisms that later 

lead to long-term distresses. Some of the primary common phenomena occurring in the early age of the 

pavement include pavement delamination and built-in curling. These two conditions are known to be 

early-age indicators of the future performance of the pavement in the long term, and are presented in the 

following section. 

2.4.1 Delamination 

2.4.1.1 Moisture Loss 

Evaporation of bleed water at the concrete surface is governed by the concrete temperature and 

climatic conditions such as windspeed, relative humidity, and air temperature. However, at any point 

during the early age of the pavement, the loss of moisture in concrete pavements will also be a function of 

the moisture transport characteristics of the concrete, the water available in the mix, and in particular, the 

water that has not been used for hydration. Moisture gradients usually develop in concrete pavements due 

to the loss of moisture to the environment. Under conditions where significant moisture is lost to the 

environment, critical moisture gradients may develop in the slab. Typical moisture gradients resulting 

from excessive moisture loss usually present a sharp drop in moisture close to the pavement surface, as 

illustrated in figure below. 
17 

Depth

0%

Relative 

Humidity

100%

Slab Thickness Depth

0%

Relative 

Humidity

100%

Slab Thickness Depth

0%

Relative 

Humidity

100%

Slab Thickness

Figure 8. Moisture gradient resulting from excessive moisture loss. 

2.4.1.2 Strength Development 

Because water available in the concrete mix is a determinant factor for the continuing hydration 

of the concrete, this hydration may be affected if excessive loss of moisture occurs. In addition, since the 

strength development is a function of hydration, the strength of the cement paste also may be affected due 

to moisture loss. Previous experience has indicated that the loss in moisture leads to reduced concrete 

strength, specifically at the surface. This reduction in concrete strength occurs because of the loss of 

strength gain in the cement paste, and in particular, at the interface between the paste and the aggregate. 

This interruption is due to the lack of water available for hydration. 

2.4.1.3 Vertical Stress Development 

Undesirable situations resulting from moisture loss are typically observed in the form of plastic 

shrinkage cracking, but also and most importantly, due to a radical change in the gradient of the moisture 

profile. Vertical tensile stresses and shear stresses develop as a consequence of the difference in 

shrinkage at different depths of the slab, as well as the pavement restraint to movement. 

2.4.1.4 Formation of Delamination 

In theory, whenever the tensile or shear stresses exceed the concrete strength, horizontal cracks 

tend to develop. The horizontal cracking that usually occurs close to joints or cracks and has typical 

depths of 13 to 76 mm is known commonly as delamination.(16) The depth of the delamination will be 

primarily a function of the evaporation rate, the type of curing, and the time to application of curing. 

Climatic conditions leading to high evaporation rates and poor curing procedures will also lead to 

significant reduction in strength and increased tensile and shear stresses in the concrete, producing deeper 

delaminations. On the other hand, climatic conditions leading to low evaporation rates and/or good 

curing procedures will typically result in shallower delaminations, and may even prevent delamination 

from occurring. 

Other concrete delamination mechanisms commonly are cited in the literature. Delaminations at 

the steel depth have been observed in some CRCP in the past. This type of delamination is attributed to 

several factors. Some projects were paved in a two-stage construction process, placing steel on top of the 

first layer of concrete in plastic state, then constructing the second layer immediately following this. In 
18 

some cases, delamination was observed due to a delay in placement of the second layer.(21) However, 

delamination of plain concrete pavements with no reinforcement also has occurred at middepth. In these 

cases, concrete placement has occurred during cold temperatures. This type of delamination has been 

attributed to sharp temperature drops, leading to excessive temperatures gradients in the slab, 

compounded with the restraint imposed by reinforcement/dowels at that location and traffic loads. 

2.4.1.5 Spalling 

Usually, the formation of delaminations is not evident in the early age; this depends on the 

subsequent climatic conditions, traffic loading, and depth. Delaminations may result in spalling distresses 

that will influence the performance of the pavement in the long term (see section 4.5). Delamination 

spalling is characterized by small pieces of concrete near cracks or joints that become loose from the 

pavement as a result of shear forces imposed by traffic loads, temperature fluctuations, and concrete 

fatigue characteristics. The amount of spalling distress and severity usually increases with time. 

2.4.2 Built-In Curling 

2.4.2.1 Temperature Gradients at Set 

The temperature gradients during the early age are a function of the environmental conditions and 

the heat of hydration of the concrete. The initial thermal gradient in the slab at set will influence the 

curling shape of the slab. 

2.4.2.2 Built-In Curling 

Built-in curling is a term used for the curling state that develops at set and that later influences the 

curled shape of the slab as the thermal gradient is subsequently modified by the hydration process and 

climatic conditions.(22) The time-dependant relaxation properties of the concrete also affect the curled 

shape of the slab. As illustrated in figure 9, if the temperature throughout the slab depth was constant 

(thermal gradient at set = 0), the curling and warping state of the slab would be a function of the 

subsequent thermal gradient and the drying shrinkage of the slab. If the thermal gradient at time t is zero, 

the shape of the slab will only be a function of the drying shrinkage and the restraint conditions of the slab 

as imposed by its own weight and the subbase (figure 9). For this case, the slab would tend to warp up 

slightly due to the drying shrinkage. However, if the thermal gradient is positive (hotter at the top than at 

the bottom), then the curling of that positive thermal gradient would tend to counteract the warping due to 

the drying shrinkage (figure 10), possibly resulting in a flat shape. On the other hand, if the thermal 

gradient is negative, then the curling of the slab toward the top will be increased by the drying shrinkage 

(figure 11), resulting in a moderately upward shape. 
19 

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

∆T(t)=0

+

20oC

slab with flat shape at set

=

slightly upward shape

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

slab shape at time (t):

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

∆T(t)=0

+

20oC

slab with flat shape at set

=

slightly upward shape

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

slab shape at time (t):

Figure 9. Effect of drying shrinkage and thermal gradient on curling and warping 

(thermal gradient at set = 0 and thermal gradient at time t = 0). 

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

+

∆T(t)=(+)

20oC

slab with flat shape at set

=

possibly flat shape

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

slab shape at time (t):

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

+

∆T(t)=(+)

20oC

slab with flat shape at set

=

possibly flat shape

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

slab shape at time (t):

Figure 10. Effect of drying shrinkage and thermal gradient on curling and warping 

(thermal gradient at set = 0 and thermal gradient at time t is positive). 
20 

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

+

∆T(t)=(-)

20oC

slab with flat shape at set

=

moderately upward shape

slab shape at time (t):

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

Assuming Thermal Gradient at Set 

∆Tset = 0 I.e. Ttop= Tbottom = 20oC

∆εs

+

∆T(t)=(-)

20oC

slab with flat shape at set

=

moderately upward shape

slab shape at time (t):

Slab

Temp.

15oC 25oC

Slab Depth Bottom

Top

Figure 11. Effect of drying shrinkage and thermal gradient on curling and warping 

(thermal gradient at set = 0 and thermal gradient at time t is negative). 

In general, when concrete sets, the temperature through the slab generally is not uniform, but 

rather is a function of the climatic conditions, the heat of hydration, and curing methods. Because there is 

a thermal gradient at set, the curling and warping of the slab at any time will be a function of that initial 

thermal gradient, the drying shrinkage, and the current thermal gradient of the slab. This is illustrated in 

figures 12–14 for a positive thermal gradient at set and in figures 15–17 for a negative thermal gradient at 

set. 

∆Tset=(+)

+

∆T(t)=0

∆εs

slab with flat shape at set

=

moderately upward shape

slab shape at time (t):

∆Tset=(+)

+

∆T(t)=0

∆εs

slab with flat shape at set

=

moderately upward shape

slab shape at time (t):

Figure 12. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set is 

positive and thermal gradient at time t = 0). 
21 

∆Tset=(+)

∆εs +

∆T(t)=(+)

slab with flat shape at set

=

slightly upward shape

slab shape at time (t):

∆Tset=(+)

∆εs +

∆T(t)=(+)

slab with flat shape at set

=

slightly upward shape

slab shape at time (t):

Figure 13. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set is 

positive and thermal gradient at time t is positive). 

∆Tset=(+)

∆εs +

∆T(t)=(-)

slab with flat shape at set

=

significant upward shape

slab shape at time (t):

∆Tset=(+)

∆εs +

∆T(t)=(-)

slab with flat shape at set

=

significant upward shape

slab shape at time (t):

Figure 14. Effect of positive thermal gradient at set on curling and warping (thermal gradient at set is 

positive and thermal gradient at time t is negative). 

For a positive thermal gradient, considering average temperature equal to the average temperature 

at set, whenever the subsequent thermal gradient becomes zero (figure 12), the pavement will tend to curl 

up due to the initial thermal gradient at set. This occurs due to the fact that the top fibers cool down from 

the initial temperature at set, and the bottom concrete fibers will warm up. This effect is accentuated by 

the warping generated due to the drying shrinkage. However, no curling is observed if the current 

thermal gradient is positive and similar to the thermal gradient generated at set (figure 13). For this case, 

the shape of the slab will only be a function of the drying shrinkage. The most critical case would be 

observed if the thermal gradient of the slab is negative, as illustrated in figure 14. For this case, the 

difference in temperature from the positive gradient at set will generate a significant amount of upward 

curling of the slab, which will be further accentuated by drying shrinkage. 
22 

A similar situation would occur for the case of negative thermal gradient at set as illustrated in 

figures 15–17. For a negative thermal gradient, the worst case would occur with a positive thermal 

gradient at time t as represented in figure 16. 

∆Tset=(-)

∆εs +

∆T(t)=0

slab with flat shape at set

=

possibly flat shape

slab shape at time (t):

∆Tset=(-)

∆εs +

∆T(t)=0

slab with flat shape at set

=

possibly flat shape

slab shape at time (t):

Figure 15. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set is 

negative and thermal gradient at time t = 0). 

∆Tset=(-)

∆εs +

∆T(t)=(+)

slab with flat shape at set

=

slightly downward shape

slab shape at time (t):

∆Tset=(-)

∆εs +

∆T(t)=(+)

slab with flat shape at set

=

slightly downward shape

slab shape at time (t):

Figure 16. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set is 

negative and thermal gradient at time t is positive). 
23 

∆Tset=(-)

∆εs +

∆T(t)=(-)

slab with flat shape at set

=

slightly upward shape

slab shape at time (t):

∆Tset=(-)

∆εs +

∆T(t)=(-)

slab with flat shape at set

=

slightly upward shape

slab shape at time (t):

Figure 17. Effect of negative thermal gradient at set on curling and warping (thermal gradient at set is 

negative and thermal gradient at time t is negative). 

2.4.2.3 Pavement Smoothness, Faulting, and Cracking 

It has been observed that built-in curling may translate later into faulting and cracking problems 

as the level of stresses developed in the pavement slabs is increased as a function of traffic loads and 

long-term daily and seasonal climatic conditions. This will affect further the curling shape and the 

support conditions under the pavement. For positive thermal gradient at set, it is believed that the 

pavement is more susceptible to corner cracks (figure 14), while for negative thermal gradient at set, the 

pavement would be more susceptible to midslab cracking (figure 16). The effect of drying shrinkage 

suggests that built-in curling would be more critical for stresses due to corner cracking than for midslab 

cracking. In addition, under certain circumstances, built-in curling could lead to a more pronounced 

curling shape of the slab, which may influence the initial pavement smoothness and, therefore, its riding 

quality during the service life. 

25 

CHAPTER 3. EARLY-AGE PAVEMENT DISTRESSES 

3.1 PLASTIC SHRINKAGE CRACKING 

Plastic shrinkage cracking is an early-age pavement distress that forms before the set of a freshly 

placed concrete pavement. Plastic shrinkage cracks are the short irregular cracks that form on the fresh 

surfaces of concrete (see figure 18). They can be from few centimeters to just under 1 m long. The crack 

spacing is irregular, varying from a few centimeters to 0.6 m apart. Plastic shrinkage cracking is caused 

by the rapid loss of water from the surfaces of the fresh concrete. The cracks form when the rate of 

evaporation is greater than the concrete’s bleeding rate. According to experience and previous research, 

conditions where the evaporation rate of a pan of water in excess of 1.0 kg/m2

/hr will cause cracks to 

form in concrete of the same temperature.(6) Caution should be exercised when the evaporation rate 

exceeds 0.5 kg/m2

/hr. 

Figure 18. Plastic shrinkage cracking in concrete pavement. 

With the loss of water from the pavement surface, there is a volumetric contraction of the fresh 

concrete. The shrinkage occurs primarily in the paste, with the aggregate acting only as restraint. These 

differential volume changes can induce tensile stresses in the pavement, and can subsequently cause 

cracks to form. The fresh concrete does not have sufficient strength to resist these capillary stresses 

within the fresh paste. There is currently no way to predict with certainty when plastic shrinkage cracks 

will form. 

The method currently used to predict evaporation rate was developed by C. Menzel in 1954. It 

uses air temperature, relative humidity, concrete temperature, and wind velocity to determine if the 

evaporation rate is high enough for plastic shrinkage cracks to form. When the rate of evaporation is 0.5 

kg/m2

/hr, cracks can occur. When the rate exceeds 1.0 kg/m2/hr, precautionary measures are mandatory. 

This procedure originally was developed based on the rate of water evaporated from a standing pan of 

water. 
26 

Evaporation of water from the surface of freshly placed concrete is primarily due to climatic 

conditions. Typically, plastic shrinkage cracking occurs when construction takes place in hot weather. 

The climatic conditions that are suitable for their formation are: 

• High concrete temperatures. 

• Low ambient relative humidity. 

• High wind velocities. 

These three conditions increase the rate of evaporation from the surface of the concrete pavement. 

Water also can be extracted from the slab by absorption or suction into the subbase and/or formwork. 

This can aggravate the water loss and promote additional cracking. 

Plastic shrinkage cracks do not always form during the hot weather months. Other factors in 

addition to climate can influence the behavior of the fresh concrete. Some cracks are caused by 

incorporating new materials into the concrete, such as excessive fines, admixtures, and fiber 

reinforcement. Fines have a greater water demand and can affect the bleed water rate. Admixtures, such 

as superplasticizers and retarders, also affect the plastic state of the concrete by making the concrete 

experience less bleeding, and delay the set. Polypropylene fibers have been effective in delaying plastic 

shrinkage cracking. Similarly, the size of the concrete structure influences plastic shrinkage, since the 

slab depth is related to bleed rate.(23) These factors influence plastic shrinkage cracking, and the method 

to predict crack formation should account for these different material constituents and size considerations. 

The loss of water from the surface of the concrete must be minimized to prevent plastic shrinkage 

cracking. One option is to moist cure the surface of the concrete immediately after placement, and to 

continue to do so for at least 24 hours. The most effective method is to keep the surface of the pavement 

wet. Other options are to erect wind barriers around the pavement or to erect sunshades to protect the 

surface from heat. 

To improve current curing practices, the Federal Highway Administration (FHWA) recently 

sponsored a research project intended to provide guidelines for curing of PCC pavements (PCCP).(24) 

These guidelines include recommendations on selecting curing methods, curing application, curing 

duration, and temperature management issues. 

Another ongoing FHWA project aims to develop a Microsoft® Pocket personal computer (PC)-

based system with guidelines on curing of PCCP using concepts in the FHWA curing guidelines study 

and in HIPERPAV II. In addition to guidelines on selecting, applying, and timing curing methods, the 

Pocket PC system will have the capability to monitor real-time concrete temperature for determining 

concrete maturity and predicting concrete strength, among other features. 

3.2 CRACKING DUE TO THERMAL SHOCK 

Placement of concrete pavements during hot weather conditions when the temperature of the air 

exceeds 32 oC, may be undesirable with respect to pavement behavior. During hot weather concreting, 

the cement hydration is accelerated by the temperature of the air and the initial high temperature of the 

mix components. Depending on the cement composition, cement fineness, and admixtures used, the 

accelerated cement hydration may result in significantly higher heat development during the first hours 

after placement. This increased hydration also reduces the set time and complicates the paving 

operations, delaying the time for proper curing. The higher heat development in the concrete mix 

increases the loss of moisture in the concrete, increasing drying shrinkage. Undesirable hot weather 

conditions can be compounded further with the use of high heat cements, high cement contents, and 
27 

certain admixtures. In addition, drastic temperature drops during the first days after concrete placement 

may significantly increase the tensile stresses in the pavement. If precautions are not taken to minimize 

the above situation, excessive stresses in the concrete pavement may develop that can result in what is 

commonly known as thermal shock, or random, uncontrolled cracking. 

Although the strength of the concrete develops faster due to the higher hydration rate, the longterm strength is usually lower than that of concrete hydrating at a lower temperature. After the first 72-

hour period, it has been found that the early-age effects (accelerated hydration and rapid strength gain) 

become minimal. 

3.2.1 Distress Manifestation on JPCP 

For the case of JPCP, thermal shock may occur in the form of random cracking before, or even 

after, the time when joints are sawed. Although these cracks may be tight initially, they may extend to 

full depth, affecting the structural integrity of the pavement. Traffic loads and subsequent temperature 

fluctuations usually will increase the extent and deterioration of the pavement, providing poor 

performance in the long term. 

3.2.2 Distress Manifestation on CRCP 

As figure 19 illustrates, thermal shock may be observed in CRCP in the form of very closely 

spaced cracks. In addition, the cracks tend to meander more than cracks developed during placements at 

lower temperatures. Also, cracks occurring during the first few hours tend to be wider than those 

occurring at later ages. The formation of longitudinal cracks is another typical distress associated with 

high temperature placement (see figure 20). According to experience, closely spaced transverse cracks 

and longitudinal cracks due to thermal shock are more prone to develop into spalling and punchout 

distresses in the long term as a consequence of traffic loadings and climate. 

Figure 19. Closely spaced cracks resulting from thermal shock in CRCP. 
28 

3.2.3 Recommended Precautions against Thermal Shock 

When significant changes in temperature are expected during the construction of concrete 

pavements, it is important to assess the risk of damage to the pavement, as well as measures that would 

keep the stresses in the concrete at an acceptable level. Alternatives such as modifying the temperature of 

the mix or curing methods to insulate the pavement from the environment may be used to control the 

pavement temperature and excessive moisture loss. 

The initial temperature of the mix can be reduced in several ways, such as cooling down the 

mixing water, sprinkling or fog spraying the aggregates, or maintaining the aggregates in shade storage. 

In addition, minimizing the concrete hauling time will reduce the time that the concrete mix is exposed to 

hot weather before placement. Scheduling placing operations during times of the day, when climatic 

conditions are not as critical, will also minimize the risk of developing extremely high temperatures in the 

concrete mix. 

Protecting concrete against moisture loss during the curing period to avoid excessive drying 

shrinkage can be accomplished by increasing the application rate of the curing compound, or by using 

curing methods that provide moisture insulation such as polyethylene sheeting. If drastic temperature 

drops are expected, a combination of curing methods such as polyethylene sheeting and cotton mats may 

be necessary to keep moisture in the concrete, and to provide a more uniform curing temperature. If 

curing procedures are not performed on time, excessive moisture loss in the pavement may not be 

avoided. 

Recommended precautions to avoid thermal shock could also include the use of low heat cements 

and supplementary cementitious materials (SCM) such as fly ash. Retarding admixtures also may be used 

to help minimize the water demand during hot weather concreting. Some retarding admixtures possess 

water-reducing and set-retarding properties. Other types of admixtures may help prevent drying of the 

surface by increasing early bleeding. However, caution must be taken that the admixtures do not reduce 

the tensile strength or tensile strain capacity of the concrete.(25)

Figure 20. Longitudinal crack in CRCP due to thermal shock. Crack is enhanced for clarity. 
29 

An important factor that can determine the potential for early-age cracking in newly constructed 

JPCP is the timing of the joint sawing operations. The purpose of joints in a jointed concrete pavement is 

to control the location of the cracking that will naturally occur during the life of the pavement. The 

majority of this cracking will occur during the early-age period as a result of restraint to volumetric 

changes. If the joints are not sawed early enough, uncontrolled cracking can result. This may lead to 

undesirable long-term performance due to poor load transfer and spalling. Therefore, sawcutting 

operations should be performed as soon as possible following construction to minimize the potential for 

uncontrolled cracking. However, when sawcutting begins is also constrained by the time required to gain 

sufficient PCC strength to support the weight of the equipment (and operator), as well as the forces 

introduced by the cutting blade during the cutting operations. 

31 

CHAPTER 4. IMPACT OF EARLY-AGE BEHAVIOR ON LONG-TERM 

PERFORMANCE 

Early-age behavior may impact the long-term performance of concrete pavements leading to a 

number of distresses. These guidelines discuss the impact that early-age behavior may have on JPCP 

faulting and cracking, CRCP punchouts, and the impact on spalling distress, which is common to both 

JPCP and CRCP. While JPCP faulting and cracking are modeled in HIPERPAV II, a spalling model was 

not included in the long-term prediction module because of the complexity required to account for all 

possible factors that affect spalling distress. Likewise, since CRCP long-term performance was out of the 

scope of the HIPERPAV II project, no punchout models were included in HIPERPAV II. It is important, 

however, that users of these guidelines understand the factors influencing spalling and punchout distresses 

and the design and construction factors that should be considered to minimize their occurrence. 

4.1 FAULTING OF JPCP WITHOUT DOWELS 

Faulting of pavements is the most predominant factor contributing to pavement roughness. 

Faulting is the difference in elevation of adjoining slabs at the joint. In JPCP without dowels at the joints, 

faulting is caused by the buildup of loose material. The location of the buildup is most commonly under 

the approach edge of the slab, hypothetically due to the erosion of subbase material from under the leave 

edge of the slab. The magnitude of faulting is affected significantly by heavy traffic loads, the type of 

subbase material, and climatic conditions that the pavement is subjected to over the course of its lifetime. 

This section outlines how early-age parameters at the time of pavement construction influence the 

long-term faulting performance of JPCP without dowels. The damage progression, initiating at early age, 

is described in the flowchart in figure 21. The early-age input (step 1) controls the concrete’s material 

properties (step 2) and the pavement’s early-age response (step 3). Material characterization describes the 

change of PCC properties, such as strength and stiffness. Early-age response describes the stresses, 

strains, and deflections that form within the pavement. With time and daily cyclic temperature changes, 

the pavement’s behavior (step 4) is apparent. Pavement behavior covers visible phenomena such as joint 

opening and curling and warping. Steps 1–4 outline the sequence of early-age processes that occur before 

distress formation. After the pavement is subjected to traffic loading and changing climatic conditions, 

the pavement behavior may lead to distress. The long-term inputs that are influential in causing faulting 

are listed in step 5. Repeated loading of the pavement will eventually cause the distress to form (step 6). 

After the distress first forms, repeated loading cycles will increase the severity of the distress. How this 

distress changes with time (long-term pavement performance) is provided in step 7. These seven steps, 

from early age to long term, are described here in greater detail. 

4.1.1 Early-Age Inputs 

The early-age inputs that govern faulting in nondoweled JPCP are listed in step 1 of figure 21. 

Faulting is caused by slab deflection at the joint. Load transfer through aggregate interlock is lost as the 

joint opens, and the pavement deflects downward due to continued mechanical and environmental 

loading. During the design stage, preventive measures should be taken to limit slab deflection. This is 

possible by constructing shoulder support or by widening the lanes. Widened lanes reduce the stresses at 

the slab edge.(26) Proper pavement curing also can help reduce the severity of built-in curling (see section 

2.4.2), which is affected by temperature and moisture. Built-in curling may contribute to faulting of the 

pavement even before traffic loads are applied. 
32 

To prevent excessive opening of the joints, joint design should be carefully evaluated. Short joint 

spacings usually translate to narrower joint openings, and larger joint spacings translate to wider joint 

openings. If the joint spacing is large, more material is available for contraction during temperature 

drops. The slab-subbase friction resists this movement, which affects the joint opening. To prevent the 

loss of aggregate interlock, a good bond between the aggregate and concrete is necessary if suitable load 

transfer is to be provided for a significant period of time. 

4.1.2 Materials Characterization 

The strength and stiffness of PCC is determined primarily by the mix design, material properties, 

construction curing practices, and climatic conditions at the time of placement. PCC mix design also 

determines the effectiveness of the aggregate interlock at the joint. Larger aggregates have been found to 

be more effective in transferring load, and therefore lead to decreased faulting.(26) PCC material 

properties also influence the early-age responses of the pavement, namely the stresses, strains, and 

deflections that develop. 

1. Early-age inputs

• PCC mix design: aggregate / 

concrete bond.

• Design: joint spacing, 

slab / subbase interface.

• Climate: temperature, moisture.

• Construction: shoulder support, 

widened lanes, curing methods.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress / strain development

• Corner deflection

4. Pavement behavior

• Joint opening

• Aggregate interlock

• Curling / warping

Before 

distress formation

7. Long-term 

performance

History of faulting

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility and gradation).

• Load transfer: aggregate 

interlock.

6. Distress

Faulting

N

1. Early-age inputs

• PCC mix design: aggregate / 

concrete bond.

• Design: joint spacing, 

slab / subbase interface.

• Climate: temperature, moisture.

• Construction: shoulder support, 

widened lanes, curing methods.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress / strain development

• Corner deflection

4. Pavement behavior

• Joint opening

• Aggregate interlock

• Curling / warping

Before 

distress formation

7. Long-term 

performance

History of faulting

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility and gradation).

• Load transfer: aggregate 

interlock.

6. Distress

Faulting

N

Figure 21. Flowchart outlining impact of early-age input on long-term faulting performance of JPCP 

without dowels. 
33 

4.1.3 Early-Age Response 

For JPCP to fault, loading one of the adjoining slabs results in deflection greater than the adjacent 

slab. It commonly is assumed that faulting initiates at a slab corner, because deflection is typically the 

greatest there. The difference in slab deflections is the result of a loss of load transfer at the joint due to 

large joint openings. Since it is necessary to maintain good load transfer at the joint, the size of the joint 

opening should be minimized. Joint opening is controlled by the stresses and strains in the pavement. 

Therefore, the internal stresses in the pavement must be controlled for optimal joint opening and reduced 

faulting in the long term. 

4.1.4 Pavement Behavior 

As mentioned previously, the size of the joint opening determines how efficient the aggregate 

interlock is in transferring load across the joint. Experimental studies have shown that a joint opening of 

0.6 mm or greater can translate to total loss of load transfer by aggregate interlock.(14) This was discussed 

in greater detail in section 2.2. Slab deflection is the other component required if a pavement is to 

develop faulting. Curling or warping is another form of slab deflection. Figure 22 illustrates how a 

deformed pavement shape promotes the ingress of water into the pavement subbase and subgrade layers. 

Pumping is more severe when the pavement is curled up or has built-in curling.(27) 

Centerline

Saturated subbase

Deflected slab

Water and incompressibles

Figure 22. Deflected pavement shape. 

4.1.5 Long-Term Inputs 

As the size of the joint opening increases and curling and warping become more apparent, 

faulting commonly will develop over time. This section identifies the long-term inputs that control the 

rate of faulting. Opening of the joint promotes water infiltration into the pavement’s underlying layers. 

Water softens the subbase and subgrade, and increases the stresses and deflections in the pavement. 

Faulting is a common distress associated with poor drainage. However, if a pavement’s drainage capacity 

is improved, faulting can be reduced effectively, especially for nondoweled JPCP.(28) 

Heavy traffic loads and climatic factors such as precipitation significantly contribute to the 

amount of faulting at a pavement joint. The repeated loading of pavement joints causes erosion of the 

subbase from under the leave edge of the slab and its buildup under the approach slab. Figures 23–25 

depict faulting in pavements with erodable base material. As the wheel load deflects the approach side of 

the concrete pavement, material is pushed toward the leave side (figure 23). This frictional erosion and 

pore water pressure generates loose fine materials. Coarse-grained soils are able to withstand the effects 

of traffic better than fine-grained ones. Then, as the wheel passes to the leave slab, the water is pushed 

back to the approach side, and the fines are deposited (figure 24). A void forms on the leave side (figure 

25), and faulting is apparent. The degree of faulting increases on sections with longer slabs.(26) The slabs 

also can rotate as a result of this mechanism.(14) Faulting sometimes can be reduced if shorter slabs are 

used. 
34 

Figure 23. Schematic of faulting progression in JPCP without dowels, wheel on leave edge of slab 

(exaggerated to show mechanism). 

Figure 24. Schematic of faulting progression in JPCP without dowels, wheel on approach edge of slab. 

Figure 25. Schematic of faulting progression in JPCP without dowels, resultant behavior at the JPCP joint 

that causes faulting. 

The amount of faulting commonly correlates with the properties of the subbase materials. 

Subbase materials that are able to resist a shear stress of 25–50 pascals (Pa) do not erode for the life of the 

pavement. Weaker subbase materials will typically experience high erosion.(29) Pavements constructed 

with cement-stabilized subbase materials, such as lean concrete bases, typically experience less faulting, 

and their corner deflections generally are reduced.(26) 

Freeze-thaw cycles also influence the magnitude of faulting. When the pavement system freezes 

during the winter months, the pavement system is stiff. However, during the winter thaw, the pavement is 

highly susceptible to traffic loadings. At this time, the subbase is saturated, causing a marked decrease in 

its strength. Pumping and erosion of the subbase accelerates. Faulting damage can increase significantly 

during this period.(15) 

4.1.6 Distress Prediction 

The three major factors that cause faulting are repeated heavy traffic loads at the joint, differential 

deflection at the joint, and thermal and moisture gradients in the slab and subbase that cause curling of the 

pavement and subbase erosion.(30) Water in the pavement subbase and subgrade layers increases the 

amount of pumping, and thereby increases the degree of faulting. Figure 26 shows evidence of faulting at 

a typical contraction joint. Faulting is determined in the field by measuring the difference in adjoining 

slab elevations 0.3 m from the pavement edge.(15) 
35 

Figure 26. Photograph of faulting in JPCP. 

4.1.7 Long-Term Performance 

Faulting increases with time as the pavement is subjected to more traffic loads and climatic 

fluctuations. As figure 27 illustrates, faulting initially grows linearly up to a point, and then grows 

nonlinearly as loading continues.(31) Faulting is commonly found to be objectionable when it exceeds 3.3 

mm.(26) 

Faulting

Cumulative load applications

Linear

growth

Nonlinear

growth

Faulting

Cumulative load applications

Linear

growth

Nonlinear

growth

Figure 27. Schematic of time growth of faulting for JPCP without dowels. 

The climatic conditions at the pavement’s location greatly influence the magnitude of faulting. 

Analysis of the Long-Term Pavement Performance database revealed that faulting is lowest in the dry-no 

freeze region, as compared to dry freeze, wet-no freeze, and wet freeze regions.(32) This result 

demonstrates the importance of water to the faulting mechanism. Temperature fluctuations also influence 

faulting. Daily expansion and contraction cycles have been found to cause up to 0.5 mm of faulting per 

year.(27)

4.2 FAULTING OF JPCP WITH DOWELS 

Faulting of pavements was discussed in section 4.1 for JPCP without dowels at the joints. This 

section discusses faulting of JPCP with dowels. Dowels at the joints effectively reduce JPCP faulting.(33) 

They commonly are used today on most high-volume roadways.(26) 
36 

In reference to figure 28, this section will describe the early-age inputs (step 1), material property 

development (step 2), and the pavement’s early-age response (step 3). Dowel-concrete bearing stress 

significantly influences faulting.(15,34) These responses are included in the pavement behavior (step 4), 

which includes joint opening, dowel looseness, and curling and warping of the pavement. Over time, as 

the pavement is subjected to traffic loading and changing climatic conditions (step 5), faulting can 

develop (step 6). Finally, the long-term faulting performance of JPCP with dowels is discussed (step 7). 

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, dowel 

properties (diameter).

• Climate: temperature, moisture.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress and strain development.

• Corner deflection.

• Dowel-concrete bearing stress.

4. Pavement behavior

• Joint opening.

• Dowel looseness.

• Curling / warping.

Before 

distress formation

7. Long-term 

performance

History of faulting

N

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type (erodibility 

and gradation).

• Load transfer: dowel bars.

6. Distress

Faulting

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, dowel 

properties (diameter).

• Climate: temperature, moisture.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress and strain development.

• Corner deflection.

• Dowel-concrete bearing stress.

4. Pavement behavior

• Joint opening.

• Dowel looseness.

• Curling / warping.

Before 

distress formation

7. Long-term 

performance

History of faulting

N

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type (erodibility 

and gradation).

• Load transfer: dowel bars.

6. Distress

Faulting

Figure 28. Flowchart outlining the influence of early-age properties on long-term faulting performance of 

JPCP with dowels. 

4.2.1 Early-Age Inputs 

Early-age inputs impact the long-term faulting performance of doweled JPCP. The parameters 

with the greatest influence are listed here. Because the dowels and the concrete interact, the concrete mix 

should be tailored for strength and durability. Likewise, the dowels should be designed for reduced 

faulting. Larger dowel bars (28.7 to 38 mm in diameter) are more effective in reducing faulting than 

smaller 25.4-mm diameter bars.(26) Similarly, decreasing the joint spacing often reduces faulting. 

Climatic conditions are important, since they determine the built-in curling at set. 

Design features are also an important consideration. Shoulder support and widened lanes can 

minimize slab deflection, especially at the corners. It is assumed that, since loaded corner deflections are 

often the largest, faulting commences here.(30) Faulting is caused by the mismatch of adjoining slab 
37 

deflections. Tied shoulders have been shown to reduce faulting by 50 percent.(35) Likewise, construction 

methods used in placing these dowels are critical to their performance, as these methods may contribute 

to dowel misalignment. Circular steel dowel bars are used to transfer vertical shear and horizontal 

bending moments between adjacent slabs. To successfully transfer load, the bars must be properly 

aligned along their longitudinal axis and must be lubricated over half their length before placement.(36) 

Dowel bar coatings are commonly used to prevent corrosion. Preventing dowel deterioration also 

translates to reduced dowel lockup.(37) 

4.2.2 Materials Characterization 

Development of the concrete’s tensile and compressive strength and stiffness significantly 

influences the behavior of doweled JPCP. Strength and stiffness determine the magnitude of pavement 

stresses, strains, and deflections. They relate step 2 in figure 28 directly to the pavement’s early-age 

response in step 3. The concrete also must interact with the dowels immediately after construction by 

resisting the dowel bearing stress. This early-age interaction means that care should be taken when curing 

the concrete to maximize its early-age strength. The concrete can be damaged if the stress exceeds its 

early-age strength. 

4.2.3 Early-Age Response 

Faulting is directly related to the bearing stress at the dowel-concrete interface. If the dowel 

bearing stress can be kept below the crushing strength of the concrete, faulting can be maintained at an 

acceptable level.(15) The early-age behavior of the concrete at set determines the magnitude of bearing 

stress. Ideally, the pavement should cure without any curling or warping, as shown in figure 29. The 

dowel is straight and does not exert any stresses on the surrounding concrete. 

Figure 29. Schematic of ideal JPCP at set (dowel bar straight). 

However, as the pavement undergoes daily temperature and moisture changes, the pavement will 

curl up and down. The dowel resists this movement and, as a result, subjects the concrete to a bearing 

stress. If the slabs curl upward, as shown in figure 30, the dowel will bend negatively (downward) to 

resist slab deformation. The concrete above the dowel is put into compression. The opposite happens 

when the slab curls down; the dowels bend positively (upward) to resist deformation. The stiffer dowels 

are more able to resist deformation, yet the resultant stresses in the dowel and at the dowel-concrete 

bearing location are higher. Fiberglass dowels have lower stiffness than steel dowels. The longitudinal 

stiffness of fiber dowels is approximately 55 gigapascals (GPa), compared to 207 GPa for steel dowels. 

The bearing stress for fiber dowels at the dowel-concrete interface is also lower than for steel.(36) At early 

ages, the concrete has not yet reached its full compressive strength, so a higher bearing stress is more 

prone to causing damage. Early-age damage to the concrete will greatly reduce the pavement’s long-term 

performance. 
38 

Direction of dowel-concrete 

bearing stresses

Centerline

Deformed dowel Curled slabs

Subbase

Direction of dowel-concrete 

bearing stresses

Centerline

Deformed dowel Curled slabs

Subbase

Figure 30. Schematic of curled JPCP connected by a dowel in bending (enlarged to show mechanism). 

4.2.4 Pavement Behavior 

The stresses, strains, and deflections that develop in the pavement at an early age influence joint 

opening and pavement curling and warping. The repeated temperature cycles may loosen the dowelconcrete interface, and therefore reduce the load transfer efficiency. Traffic loadings aggravate this 

condition, as is discussed in the next section. 

4.2.5 Long-Term Inputs 

Long-term inputs affect the doweled and nondoweled pavements similarly (section 4.1). Faulting 

increases as traffic and precipitation increase. Good drainage and a stabilized subbase can reduce 

faulting. Climatic conditions also influence faulting of the doweled pavements, but not as 

significantly.(35)

Over time, the number of thermal and moisture cycles a pavement experiences accumulates. The 

joints open and close as the pavement expands, contracts, curls, and warps.(30) Similarly, the dowel 

continues to subject the concrete to compressive stresses. High bearing stresses are commonly found at 

the dowel-concrete interface due to this cyclic loading. Traffic loading also increases the bearing stresses, 

as shown in figure 31. In this figure, the dowel-induced stresses are on the upper half of the pavement’s 

approach slab and on the lower half of its leave slab. This can cause crushing of the concrete in adjoining 

pavements over time.(36) This loss of concrete forms voids at the dowel-concrete interface and reduces 

load transfer efficiency. 

 

Compressive stresses 

Figure 31. Schematic of wheel load on JPCP with dowels (dowel enlarged to show bearing stresses). 

4.2.6 Distress Prediction 

Faulting in doweled JPCP is caused, in part, by dowel loosening and enlargement of the dowel 

socket. The reasons for doweled pavement faulting are similar to those for nondoweled pavements. They 

include heavy traffic loading, differential deflection at the joint, and thermal and moisture gradients that 

cause slab curling and subbase erosion. In the case of doweled pavements, these three mechanisms 
39 

loosen the dowel, reducing the load transfer efficiency and causing concrete crushing at the dowelconcrete interface. A photograph of faulting distress was shown in figure 26. 

4.2.7 Long-Term Performance 

The relationship of faulting versus traffic is shown in figure 32 for JPCP with dowels at the 

joints.(35) Initially, faulting increases rapidly. Then, with time and increased traffic, the faulting levels 

off. Dowels can significantly reduce faulting, when compared to JPCP without dowels. See section 4.1 

for more details on faulting of JPCP without dowels. 

Faulting of doweled pavements can also lead to other distresses, such as spalling and transverse 

cracking. If the dowel bearing stresses are too severe, concrete above the dowels can break off to form a 

spall. This is discussed in more detail in sections 4.5 and 4.6. Transverse cracking is also possible if the 

doweled joints are improperly constructed. Dowel misalignment can cause a transverse crack to form 

near the joint. For more details on this distress, see section 4.3. Faulting

Traffic

Levels off

Rapid 

initial growth

With dowels

Without dowels

Faulting

Traffic

Levels off

Rapid 

initial growth

With dowels

Without dowels

Figure 32. Schematic of time and traffic growth of faulting for JPCP with doweled joints. 

4.3 JPCP TRANSVERSE CRACKING 

Transverse cracking of JPCP can develop at early ages immediately after construction, or it can 

form years later due to fatigue. However, the mechanisms that cause these cracks to form are different. 

At early ages, transverse cracks form because of restrained volume changes. Concrete tends to expand 

and contract due to changing climatic conditions. When these internal deformations are restrained by 

external slab-subbase restraint and self-weight, early-age transverse cracking is possible.(2) Because 

young concrete has not yet reached its full mature strength, it is more susceptible to tensile damage. More 

detail on this type of cracking is provided in section 3.2. 

When transverse cracks form after years of pavement use, the most common cause of cracking is 

fatigue. Over time, the cumulative number of traffic loadings increase, as do the number of seasonal 

climatic cycles. Stresses are generated in the concrete, and eventually a transverse crack can form. 

Transverse cracks can either propagate from the top of the pavement down (top-down cracking), or they 

can propagate from the bottom of the pavement up (bottom-up cracking). The difference between these 

two cracking mechanisms is discussed in the following sections. 

This section examines how early-age inputs influence transverse cracking in JPCP over the long 

term. A flowchart connecting early-age input to the long-term performance of JPCP is shown in figure 

33. The six fields presented in that figure are discussed in greater detail in the following sections. 
40 

4.3.1 Early-Age Inputs 

Early-age inputs that have a significant influence on transverse crack formation are listed in step 

1 of figure 33. The concrete mix design will determine the strength and fracture properties of the 

concrete at early ages and in the long term. The coarse and fine aggregate percentages also can influence 

the amount of transverse cracking to the level aggregate gradation affects drying shrinkage.(35) Pavement 

design also controls the stresses generated in the pavement. Widened pavements can significantly 

decrease the pavement edge stresses that cause transverse cracking. Joints alleviate tensile stresses that 

occur in the pavement at early ages. Shorter joints decrease frictional stresses at the slab-subbase 

interface and decrease the severity of transverse cracking in the long term. Slab thickness also has a 

significant influence on transverse cracking.(38) Thicker slabs are better able to resist deformation, and 

they are better able to carry mechanical and environmental loading.(26) 

Climatic conditions at the time of pavement construction have a marked influence on long-term 

pavement performance. The temperature gradient at the time of set determines the amount the pavement 

curls up or down, and the moisture gradient controls the amount of warping. This built-in curling is 

discussed in section 2.4.2. Climatic conditions influence the set time and thermal gradient at set, and 

therefore significantly influence the magnitude of stresses generated over the long term. Finally, 

construction methods are critical in controlling transverse cracking. Time of joint sawing is important to 

control, since the joints are designed to alleviate internal pavement stresses and control where the cracks 

form. Both of these construction methods can improve the pavement’s long-term performance. 
41 

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, slab 

thickness, slab-subbase interface, 

widened lanes. 

• Climate: temperature gradient, 

Moisture gradient.

• Construction: joint sawing.

2. Materials characterization

• PCC strength / stiffness.

• PCC fracture properties.

3. Early-age response

• Stress, strain, and deflection. 

• Drying shrinkage.

4. Pavement behavior

• Microcrack formation.

• Curling / warping.

Before 

distress formation

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles, 

seasonal temperatures.

• Drainage.

• Subgrade support: base 

type / soil type. 

• Fatigue: stress / strength 

ratio.

6. Distress

Transverse 

cracking

7. Long-term 

performance

History of transverse 

cracking

N

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, slab 

thickness, slab-subbase interface, 

widened lanes. 

• Climate: temperature gradient, 

Moisture gradient.

• Construction: joint sawing.

2. Materials characterization

• PCC strength / stiffness.

• PCC fracture properties.

3. Early-age response

• Stress, strain, and deflection. 

• Drying shrinkage.

4. Pavement behavior

• Microcrack formation.

• Curling / warping.

Before 

distress formation

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles, 

seasonal temperatures.

• Drainage.

• Subgrade support: base 

type / soil type. 

• Fatigue: stress / strength 

ratio.

6. Distress

Transverse 

cracking

7. Long-term 

performance

History of transverse 

cracking

N

Figure 33. Flowchart outlining impact of early-age input on long-term transverse cracking performance 

of JPCP. 

4.3.2 Materials Characterization 

The strength and fracture properties of concrete have a significant impact on transverse cracking. 

The stiffness of the concrete determines the magnitude of induced stresses and deflections. The strength 

and fracture properties control when the concrete cracks. 

Fatigue of concrete has been shown to be a function of the stress-to-strength ratio.(39) A highstrength concrete will commonly have a greater fatigue life than a low-strength concrete. However, highstrength concrete also can have higher stress concentrations at flaws or microcracks, making it brittle. 

Pavements constructed of concrete with high flexural strength typically fracture more easily.(35) For this 

reason, it is recommended that concrete strength be kept within a midrange from 4.5 to 4.8 megapascals 

(MPa). 
42 

4.3.3 Early-Age Response 

The pavement’s critical stresses can either occur at the bottom of the pavement (bottom-up 

cracking) or at the top of the pavement (top-down cracking). The mode of failure depends, in part, on the 

pavement’s “built-in” temperature gradient. The term “built-in” is in quotes because it is not really a 

fixed property. However, for simplicity, it is commonly assumed to be the temperature gradient at final 

set. To better explain some of the more fundamental concepts, it will be defined in this manner for the 

discussion to follow. However, this gradient truly is not fixed, but will instead change with time as the 

stresses in the slab relax. 

As figure 34 illustrates, when there is a positive temperature gradient at set, the pavement sets 

with its top surface hotter than its bottom one. Typically, this happens when the pavement is constructed 

in the morning or afternoon. Eventually, when the slab cools, it will curl up. 

HOT Positive temperature gradient

COLD

Centerline

Figure 34. Schematic of JPCP with a positive temperature gradient at set. 

Figure 35 illustrates that if a pavement has a negative temperature gradient at the time of set, the 

slab surface will be cooler than the slab bottom. This scenario is possible for night paving. If the 

pavement’s surface is hotter than the bottom during subsequent seasonal temperature changes, the 

pavement may curl downward. 

Negative temperature gradient COLD

HOT

Centerline

Figure 35. Schematic of JPCP with a negative temperature gradient at set. 

Upward curling is less restrained than downward curling because only the corners of the slab lift. 

Downward curling requires that the slab joints bear down on the subbase (see figure 36). This downward 

curling requires more force than the upward curling.(22) Drying shrinkage most commonly increases the 

tensile stresses at the pavement surface due to an increase in the degree of upward slab curling.(39) For the 

first 72 hours after construction, the pavement’s expansion and contraction stresses are partially restrained 

by the slab-subbase friction. If the internal stresses are greater than the strength of the concrete, 

transverse cracks may form. If the joints are sawed at the optimal time, early-age uncontrolled transverse 

cracking can be prevented. If dowels are used at the pavement joint and are significantly misaligned, 

transverse cracks can form at the joint. Care must be taken to construct and maintain the pavement 

properly to prevent dowel bar corrosion. Dowel bar corrosion may lead to a locked transverse joint, 

which may cause additional transverse cracks to form.(40) Even if no transverse cracks form in the 

pavement at early ages, they may still form in the long term due to fatigue. The upward and downward 
43 

built-in set conditions increase the likelihood of midslab crack formation due to subsequent mechanical 

and environmental loading. This is discussed in section 4.3.5. 

4.3.4 Pavement Behavior 

Repeated tensile stresses in the pavements initially can damage the concrete at the microscopic 

level. Eventually, microcracks form that act as stress concentrators. After these microcracks have 

lengthened and connected, a macroscopic crack will form. 

Curling and warping stresses subject the pavement to tensile damage, and help generate 

transverse cracks. As mentioned in section 2.4.2, built-in downward curling at set due to negative thermal 

temperature gradients increases the tensile stresses at midslab. The combination of thermal gradients and 

traffic loading assist in transverse crack formation. 

Tensile stresses at pavement bottom

Pavement edges 

bear into subbase

Centerline

Figure 36. Schematic of curled-down JPCP. Note the pavement lifts off the subbase at midslab, and its 

edges bear on the subbase. 

4.3.5 Long-Term Inputs 

Even though the pavement may resist transverse crack formation at early ages, cracks may still 

form in the long term due to fatigue. Fatigue loading causes any flaws in the concrete to lengthen. 

Repeated loads cause the microscopic flaws to blunt and resharpen until they form into a visible crack.(41) 

Fatigue depends primarily on the ratio of induced stresses to the concrete’s strength. Miner’s damage law 

typically is used to calculate the amount of damage a pavement sustains over its lifetime. 

The two most significant factors affecting long-term fatigue are the combined effects of traffic 

and environmental loading.(26) Traffic loads increase the stresses to which the pavements are subjected. 

They contribute considerably to bottom-up and top-down transverse crack formation. As figure 37 

demonstrates, for bottom-up cracking, the critical stresses that cause transverse cracking are at the 

pavement’s midslab edges.(15) 
44 

Location of critical 

edge stresses

Centerline

Joint Joint

Figure 37. Plan view of JPCP slab showing location of critical edge stresses that cause transverse 

cracking at midslab. 

Figure 38 demonstrates how wheel loading during the service life causes the pavement to deflect 

downward, putting the bottom of the pavement in tension. Traditionally, transverse cracking is assumed 

to initiate at the bottom of the pavement. 

Tensile stresses at pavement bottom

Deflection, δ

Figure 38. Schematic of curled-up JPCP. 

Similarly, wheel loading can put the bottom of the slab in tension when it is curled down. The 

interior of the slab may not have contact with the subbase when it is curled down.(15) This loss of support 

increases the likelihood of midslab transverse cracking. 

Environmental loading changes subbase support. The subbase sometimes erodes, settles, pumps, 

or heaves, all of which negatively impact pavement performance.(38) The development of these subbase 

phenomena is often directly related to precipitation amounts. Figure 38 demonstrates that, for a curled-up 

pavement, the water softens the subbase, therefore increasing midslab deflection and, consequently, the 

tensile stresses at the bottom. For this scenario, the potential of bottom-up cracking is increased. For a 

curled-down pavement, loss of subbase support, coupled with traffic loading close to the joint, put the 

surface of the curled-down pavement in tension, increasing the potential for top-down cracking. This can 

be seen in figure 39. 
45 

Severe erosion

of subbase

Tensile stress

Figure 39. Schematic of top-down JPCP transverse cracking due to severe erosion of subbase. 

Seasonal freeze-thaw cycles further aggravate the effect of water. Freezing can stiffen the 

subbase and the subgrade during the winter months. During the subsequent thaw cycle, the pavement is 

most susceptible to damage. The subbase soils cannot sustain the loading, so they erode and pump at a 

faster rate. This increases the pavement damage.(17) As shown in figure 39, severe erosion of the subbase 

under the pavement makes transverse cracking due to top-down cracking possible, because the loss of 

support puts the pavement surface in tension. 

While erodable subbases often are not desirable, the use of cement-treated or lean concrete bases 

also can lead to problems. Pavements built on these bases can also have significant amounts of transverse 

cracking. Since these impermeable subbases lack flexibility, water can trap beneath the slab and the 

subbase to form voids. Fines that buildup under the slab create areas of high stress, and transverse 

cracking can result.(38) Lean concrete bases also cause the pavements to develop large curling and 

warping stresses, increasing transverse cracking potential.(33) 

Pavement system drainage is one of the most significant factors governing long-term pavement 

performance. Pavements in extreme climates (wet and freezing) sometimes perform badly.(33) The 

presence of water in the pavement system and subbase and subgrade layers leads to premature pavement 

damage. Coarser subgrades typically have better drainage than fine grained ones, resulting in better 

performance when they are used.(39) 

Seasonal temperature changes are another environmental factor that can lead to pavement 

damage. Temperature changes can induce large thermal changes in the pavements. For example, 

pavements constructed in hot and dry climates have been found to have more transverse cracks than those 

constructed in milder climates.(33) 

4.3.6 Distress Prediction 

Figure 40 shows a transverse crack that formed due to fatigue. As mentioned in the above 

sections, transverse cracks are the result of early-age factors such as concrete strength and fracture 

properties, pavement geometry, and climatic conditions. Early-age conditions due to these factors result 

in curling and warping shapes and bending stresses that, when combined subsequently with traffic loads, 

climate, and level of subgrade support, cumulatively damage the pavement structure. According to the 

level of bending stresses and concrete fatigue characteristics, the pavement may eventually crack. 
46 

Transverse Crack

Joints

Figure 40. Photograph of transverse crack. Transverse crack and joints enhanced for clarity. 

4.3.7 Long-Term Performance 

Figure 41 shows how the percent of cracked slabs in a pavement versus time follows an S-shaped 

curve.(38) Initially, pavement fatigue is low, so transverse cracks are not likely to form. However, after 

the pavement has sustained a critical number of loads, the number of cracked slabs increases significantly. 

Over time, the number of transverse cracks commonly levels off. The critical level of cracked slabs in 

JPCP associated with pavement failure is commonly reported as 10 percent.(26) % Cracked Slabs

Cumulative Load Applications

Without early-age cracking

With early-age cracking

Figure 41. Schematic of long-term performance of JPCP: Percent cracked slabs vs. time. 

The formation of transverse cracks can increase other pavement distresses. Because water can 

infiltrate the cracks and weaken the subbase below, the pavement deflection will increase. As a result, 

increased faulting is possible.(35) The concrete also may deteriorate at this joint, resulting in increased 

spalling. 
47 

4.4 JPCP CORNER CRACKING 

This section highlights the influence of early-age inputs on the long-term performance of JPCP 

with respect to corner breaks. Corner breaks are more likely to form in the long term if certain early-age 

phenomena occur. These phenomena depend on design and construction parameters. 

For example, the probability that corner breaks will form increases if the pavement has built-in 

upward curling. Built-in upward curling was discussed in detail in section 2.4.2. In simple terms, it is the 

result of a positive temperature gradient (the temperature at the slab surface is greater than at the bottom). 

This typically occurs when the pavement is placed during the summer in the morning or afternoon. A 

decrease in the temperature gradient through the pavement causes the slab to curl up. Drying shrinkage at 

the surface of the pavement enhances the slab’s curled-up shape. 

Over time, the deformed shape accelerates the deterioration of the pavement. Subbase support is 

more likely to erode from under the pavement, as water infiltrates at a faster rate. Load transfer at the 

joint will also decrease. Heavy traffic loadings and seasonal temperature changes will induce high tensile 

stresses on the pavement surface, increasing the potential for development of corner breaks. 

A flowchart indicating the early-age mechanisms influencing corner cracking distress of JPCP is 

shown in figure 42. 

4.4.1 Early-Age Inputs 

Material, design, and construction procedures all influence the long-term corner cracking 

performance of JPCP. The mix design controls the strength and stiffness development of the concrete, as 

well as its fracture properties. The pavement design also affects the magnitude of stresses in the 

pavement. For example, skewed joints have been found to increase the number of corner breaks.(26) 

Thick slabs are able to sustain mechanical and environmental loadings better than thin ones. 

Climatic conditions determine the shape of the pavement at set by defining the temperature and 

moisture gradients. Set conditions determine how the pavement will deform as it undergoes climatic 

changes throughout its lifetime. A positive temperature gradient at set commonly translates to a 

pavement with a predominately curled-up shape, except when the surface is heated to a higher 

temperature than it was at set. However, a pavement with a negative temperature gradient at set can 

transition from a curled-up shape to a downward curled pavement. Built-in curling determines the 

location of the critical tensile stresses in the pavement and the likely long-term pavement distresses. 

Finally, construction practices and design features can influence the stress state of the pavement, 

from the early ages throughout its lifetime. Shoulder support can reduce slab deflection at the corners, 

while widened lanes reduce the pavement’s edge stresses. The wheel loading on widened pavements no 

longer occurs at the pavement’s edge. Instead, the loading occurs closer to the pavements interior. These 

construction methods may extend the pavement’s life by several years. 
48 

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, slab 

thickness.

• Climate: temperature gradient, 

moisture gradient.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

• PCC strength / stiffness.

• PCC fracture properties.

3. Early-age response

• Stress. strain, and deflection.

• Drying shrinkage.

4. Pavement behavior

• Microcrack formation.

• Curling / warping.

Before 

distress formation

5. Long-term Inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles, 

seasonal temperatures.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility & gradation).

• Load transfer.

• Fatigue: stress / strength 

ratio.

7. Long-term 

performance

History of corner cracking

N

6. Distress

Corner breaks

1. Early-age inputs

• PCC mix design.

• Design: joint spacing, slab 

thickness.

• Climate: temperature gradient, 

moisture gradient.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

• PCC strength / stiffness.

• PCC fracture properties.

3. Early-age response

• Stress. strain, and deflection.

• Drying shrinkage.

4. Pavement behavior

• Microcrack formation.

• Curling / warping.

Before 

distress formation

5. Long-term Inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles, 

seasonal temperatures.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility & gradation).

• Load transfer.

• Fatigue: stress / strength 

ratio.

7. Long-term 

performance

History of corner cracking

N

6. Distress

Corner breaks

Figure 42. Flowchart outlining the influence of early-age properties on long-term JPCP corner breaks. 

4.4.2 Materials Characterization 

Concrete material properties can influence the long-term performance of the pavement 

significantly with regard to corner cracking. The stiffness of the concrete governs the magnitude of the 

stresses within the pavement. This determines how severely the concrete will curl at the pavement edges 

due to mechanical wheel and environmental loading. Fracture properties and strength of the concrete are 

also important, because they determine the pavement’s resistance to cracking. To reduce the severity of 

corner breaks, a lower stiffness material with high fracture resistance (strength) is needed. However, 

because these two requirements are commonly contradictory for concrete materials, a compromise should 

be made at the time of design. 

4.4.3 Early-Age Response 

The early-age factors mentioned previously influence the pavement response, including the earlyage stresses, strains, and deflections. Their magnitude will influence the pavement performance 

significantly over its lifetime. The early-age stresses govern the degree of built-in curling. Upward 

curling causes the slab corners to lift. Downward curling requires that the slab joints bear down into the 

subbase. The slab length is stressed against its self-weight. This requires more force than upward 
49 

curling.(39) Over the lifetime of the pavement, the curling can transition from upward to downward, or 

vice versa. However, drying shrinkage nearly always acts to curl the slab upward, placing the surface in 

tension. 

4.4.4 Pavement Behavior 

During the early-age period, upward built-in curling and drying shrinkage are the primary 

conditions for the development of corner breaks. As figure 43 illustrates, microcracks later form because 

the tensile stresses placed on the pavement induce damage as the corners deflect. Over time, these 

microcracks, not visible to the naked eye, will lengthen and form a visible crack as a result of fatigue 

loading. 

Centerline Top-down cracking Centerline

Figure 43. Schematic of top-down JPCP corner cracking in pavements with built-in curling and reduced 

subbase support and load transfer. Wheel loading results in top-down cracking. 

4.4.5 Long-Term Inputs 

With the initial microcrack formation and the pavement’s built-in curling, it is more likely that 

corner breaks will form in the long term due to heavy traffic loading and the changing climatic conditions. 

However, if the pavement maintains suitable load transfer across the joints, fatigue damage can be 

delayed, reducing the number of corner breaks. However, when load transfer is lost, the joint allows 

water to infiltrate the pavement system. For a granular subbase, the annual precipitation and freeze-thaw 

cycles cause it to erode. If the pavement has adequate drainage, then the rate of erosion will not be as 

severe. For stabilized bases, corner cracking is still possible, because the pavement loses support when it 

lifts off the stiff subbase. 

The loss of subbase support due to built-in curling or subbase erosion is aggravated by heavy 

traffic loading. When loaded, the pavement surface is in tension, so top-down corner cracking is the 

mode of failure as shown in figure 43. Traffic is one of the major factors that influence the pavement 

surface’s state of stress, but thermal gradients caused by seasonal temperature changes can have a similar 

effect. At a certain temperature or time of day, the curling stresses can equal or exceed the wheel 

stresses.(39) This demonstrates the importance of thermal gradients on pavement performance. 

4.4.6 Distress Prediction 

A photograph of two corner breaks is provided in figure 44. 
50 

Joints

Corner Breaks

Figure 44. Photograph of corner breaks. Joints and corner breaks are enhanced for clarity. 

Several criteria must be met for a crack to be classified as a corner break. The crack must extend 

vertically through the thickness of the slab. Also, as figure 45 shows, the crack must intersect both the 

transverse joint and the longitudinal joint at less than 1.8 m from the slab corner.(15) 

Midslab

Joint Joint

1.8 m

1.8 m

Corner break

Midslab

Joint Joint

1.8 m

1.8 m

Corner break

Figure 45. Plan view of JPCP showing a corner break. 

4.4.7 Long-Term Performance 

A typical curve showing the growth of corner breaks as a function of cumulative load 

applications is given in figure 46. The shape of this curve is similar to the one for transverse cracking 

(section 4.3). Initially, the percentage of corner breaks is relatively minor when the pavement is first 

loaded. But as climatic cycles and wheel loadings increase, the number of corner breaks rises sharply. 

After this rapid period of growth, the cracking damage typically levels off. 
51 

% Corner Breaks

Cumulative Load Applications

Figure 46. History of JPCP corner breaks. 

4.5 DELAMINATION SPALLING 

Spalling distress is the cracking, breaking, or chipping of the slab edges within 0.6 m of the joint 

or crack.(15) Several factors have been found to contribute to development of spalling in concrete 

pavements. Some of the most common factors include: moisture loss at the pavement surface, presence 

of incompressibles at the joint, freeze-thaw action, traffic loads, mix proportioning, weak concrete at the 

surface due to poor finishing techniques, aggregate type used, width of the crack, type of joint sealant, 

and poorly designed or constructed load transfer devices. (See references 15, 16, 42, and 43.) 

This section describes the mechanisms involved in developing spalling distress primarily due to 

moisture loss at the surface. A schematic representation of these mechanisms, and the processes 

involved, is presented in figure 47. 
52 

1. Early-age inputs

6. Distress

3. Early-age response

4. Pavement behavior

5. Long-term inputs

• Traffic loads.

• Stress / strength (fatigue).

• Climatic conditions: 

precipitation / FT cycles.

• Incompressibles at the 

joint.

• Mix design: PCC strength.

• Climate: temperature, windspeed 

(evaporation from PCC ).

• Construction: curing.

• Moisture gradient.

• Shear stresses.

• Delamination.

• Horizontal cracking.

7. Long-term 

performance

History of spalling

N

2. Materials characterization

Strength development

Spalling

1. Early-age inputs

6. Distress

3. Early-age response

4. Pavement behavior

5. Long-term inputs

• Traffic loads.

• Stress / strength (fatigue).

• Climatic conditions: 

precipitation / FT cycles.

• Incompressibles at the 

joint.

• Mix design: PCC strength.

• Climate: temperature, windspeed 

(evaporation from PCC ).

• Construction: curing.

• Moisture gradient.

• Shear stresses.

• Delamination.

• Horizontal cracking.

7. Long-term 

performance

History of spalling

N

2. Materials characterization

Strength development

Spalling

Figure 47. Flowchart outlining impact of early-age input on long-term delamination spalling distress for 

JPCP and CRCP. 

During pavement construction, early-age inputs such as materials, climate, and construction 

procedures affect the strength and stress development in the pavement. During this early-age period, 

development of stresses exceeding the strength of the concrete may result in delamination areas near 

cracks or joints. These delaminated areas later interact with long-term variables such as traffic, climate, 

and other factors that contribute to spalling distress. In the long term, during the service life of the 

pavement, the distress progression is a result of the initial pavement behavior and the long-term inputs. A 

more detailed discussion about each one of the processes contributing to spalling development is provided 

in the following sections. 

4.5.1 Early-Age Inputs 

As discussed in section 2.4.1, potential for delamination is a function of the strength development 

and shear stresses produced by the drying shrinkage differential throughout the slab depth. 
53 

Primary factors that contribute to strength development and to the level of shearing stresses in the 

slab are: 

• Mix proportioning characteristics (such as amount and type of coarse aggregate, w/c ratio, 

cement content, and admixtures used). 

• Climatic conditions (such as temperature of the air, relative humidity and windspeed). 

• Construction procedures (such as curing methods and curing timing). 

4.5.2 Material Characterization 

The factors affecting the strength development in the concrete are discussed in section 5.2.6. For 

delamination spalling, the strength of the concrete is primarily affected by loss of moisture at the surface. 

Moisture loss at the surface results in a moisture gradient in the slab, as shown in figure 48. Due to the 

moisture gradient, the rate of strength development will decrease for the concrete at the surface. 

Therefore, the concrete strength will not be uniform throughout the pavement depth as shown on figure 

49. It is important to note that the concrete strength throughout the pavement depth also will be a 

function of the temperature gradient, and the moisture loss at the bottom of the pavement as affected by 

moisture conditions at the subbase. 

Depth

0%

Relative 

Humidity

100%

Sla

b

T

hic

k

n

e

s

s

Depth

0%

Relative 

Humidity

100%

Sla

b

T

hic

k

n

e

s

s

 

Figure 48. Relative humidity as a function of slab depth. 
54 

Depth

Strength

f

y

Sla

b

T

hic

k

n

e

s

s

Depth

Strength

f

y

Sla

b

T

hic

k

n

e

s

s

Figure 49. Strength development as a function of slab depth. 

Reduced strength of the concrete at the surface also has been attributed to problems with 

inadequate mix proportioning combined with poor finishing practices. Mixes with high contents of fine 

aggregate and cement often result in segregation problems that can result in weak concrete at the surface, 

especially if overworked. Other contributing factors include poor consolidation (high entrapped air) and 

lack of entrained air when concrete resistant to freezing and thawing is required.(42)

4.5.3 Pavement Response 

The moisture gradient also can produce a drying shrinkage differential in the slab. Because the 

pavement is restrained by its own weight, the subbase, and reinforcement in the case of doweled 

pavement or CRCP, shear stresses tend to develop throughout the slab depth, as shown in figure 50. 

Depth

Stress

Sla

b

T

hic

k

n

e

s

s

σy

Depth

Stress

Sla

b

T

hic

k

n

e

s

s

σy

 

Figure 50. Shear stresses as a function of slab depth. 

4.5.4 Pavement Behavior 

In theory, whenever the tensile or shear stresses exceed the concrete strength, cracking in a 

horizontal plane parallel to the pavement surface will tend to develop, as illustrated in figure 51. These 
55 

horizontal cracks usually occur close to joints or crack, and have typical depths of 13 to 75 mm. These 

cracks are commonly known as delamination.(16)

The depth of the delamination will be primarily a function of the evaporation rate, the type of 

curing, and the time to application of curing. 

Delamination

Depth

Strength/

Stress

f

y

S al b Th ci kness

σy

Depth of 

Delamination

Figure 51. Delamination mechanism. 

4.5.5 Long-Term Inputs 

Although the formation of delamination planes may not be evident in the early age, subsequent 

climatic fluctuations, coupled with traffic loading, will induce tensile stresses at the area of the 

delaminated concrete that eventually break continuity with the pavement. Depending on the shape and 

depth of the delamination, concrete strength, level of stresses that develop, and the fatigue properties of 

the concrete, vertical cracks may form at those locations, as illustrated in figure 52. 

Delamination

Wheel Load

Vertical Crack

Figure 52. Vertical cracks at delaminated areas leading to spalling distress. 

As mentioned in section 2.3.3, other concrete delamination mechanisms include delamination at 

the steel depth in CRCP due to steel corrosion, two-layer concrete construction, excessive temperatures 

gradients in the slab, and restraint imposed by dowels. 

4.5.6 Distress Prediction 

Depending on the magnitude of traffic loads, temperature fluctuations, and concrete fatigue 

characteristics, the vertical cracks formed at the delaminated areas eventually translate into spalling 
56 

distresses. Delamination spalling is characterized by small pieces of concrete near cracks or joints that 

come apart from the pavement as a result of traffic and environmental forces. Spalling distresses affect 

the riding quality and the structural integrity of the pavement, and therefore affect the performance of the 

pavement in the long term. Spalling also reduces the pavement cross section, and therefore the load 

transfer efficiency is reduced across joints or cracks.(44) Typical cases of delamination spalling are 

presented in figures 53 and 54. 

Figure 53. Delamination spalling at a CRCP crack. 

Figure 54. Round-shaped aggregates at a spalled CRCP crack. 
57 

4.5.7 Pavement Long-Term Performance History 

The depth of the delamination correlates with the evaporation rate occurring in the early age. 

According to experience, high evaporation rates in the early age lead to higher depths of delamination. In 

the long term, as observed in figure 55, low evaporation rates usually produce a greater rate of spalling 

than high evaporation rates in the first few years. However, the spalling rate tends to flatten out faster, as 

opposed to high evaporation rates, where the spalling development keeps increasing. This phenomena is 

attributed to the fact that low evaporation rates produce shallower delamination depths than high 

evaporation rates. Due to the proximity to the surface, delaminations with shallower depths are more 

prone to being affected by traffic loads than delamination of greater depths. Depending on the fatigue 

characteristics of the concrete, deeper delaminations will start to be affected later and usually will result 

in a higher severity spalling. In some cases, the development of spalling distress may occur during 

construction operations or early in the life of the pavement. 

0

5

10

15

20

25

0 5 10 15 20

Age (yrs)

Mean Cracks Spalled per 300 m

High evaporation rate

Low evaporation rate

Figure 55. Spalling progression as a function of evaporation rate.(16)

4.6 DEFLECTION SPALLING 

Deflection spalling generally is found on airport pavements or on very thin slabs. On airport 

pavements, spalling is caused by heavy aircraft loads. The heavy vertical loadings deflect the concrete 

pavements significantly at the joints and/or cracks. If the joint or crack is tight, or if incompressibles are 

present, the tops of the adjoining slabs bear on each other, and the concrete crushes. The breaking and 

chipping of the concrete is termed a deflection spall. Deflection spalls also form in thin slabs, such as 

ultrathin whitetopping, because the thin slabs also experience high deflection. Deflection spalls are not 

commonly found on interstate highway pavements thicker than 200 mm. The flowchart connecting earlyage mechanisms to deflection spalling is shown in figure 56. Each of the seven sections are discussed in 

greater detail below. Deflection spalls can form in both CRCP and JPCP pavements. 
58 

1. Early-age inputs

• PCC mix design.

• Design: joint spacing.

• Climate: temperature gradient, 

moisture gradient.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress and strain development.

• Corner deflection.

4. Pavement behavior

• Joint opening.

• PCC crushing.

Before

distress formation

7. Long-term 

performance

History of spalling

N

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility and gradation).

• Load transfer.

6. Distress

Deflection 

spalling

1. Early-age inputs

• PCC mix design.

• Design: joint spacing.

• Climate: temperature gradient, 

moisture gradient.

• Construction: shoulder support, 

widened lanes.

2. Materials characterization

PCC strength / stiffness

3. Early-age response

• Stress and strain development.

• Corner deflection.

4. Pavement behavior

• Joint opening.

• PCC crushing.

Before

distress formation

7. Long-term 

performance

History of spalling

N

5. Long-term inputs

• Traffic loads.

• Climatic conditions:

precipitation / FT cycles.

• Drainage.

• Subgrade support: base 

type / soil type 

(erodibility and gradation).

• Load transfer.

6. Distress

Deflection 

spalling

Figure 56. Flowchart outlining the impact of early-age input on long-term deflection spalling 

performance for JPCP and CRCP. 

4.6.1 Early-Age Inputs 

The early-age inputs that impact deflection spalling are listed in step 1 of figure 56. The inputs 

address concrete mix design, pavement design, climatic conditions, and construction practices. The 

concrete mix should be tailored for optimal concrete strength. The joint/crack spacing in the pavement 

should be designed to keep the joint/crack openings tight, even when the pavement is subjected to 

climatic temperature and moisture changes. Construction practices should aim to reduce corner 

deflections. Similarly, the fresh concrete should not be overworked at the pavement’s surface during 

construction because this weakens its strength. 

4.6.2 Materials Characterization 

The concrete’s strength and stiffness development is important. Concrete strength at the edges of 

the adjoining pavements needs to be maintained to prevent crushing of the concrete. 
59 

4.6.3 Early-Age Response 

The stresses and strains generated in the early-age pavement control the size of the joint opening. 

Likewise, the corner deflection of the pavement will later control the degree of deflection spalling. 

4.6.4 Pavement Behavior 

The size of the joint opening controls the efficiency of load transfer. Loss of load transfer means 

that joint deflection will increase. Similarly, the pressure on the concrete at the joint increases when 

loaded vertically. 

4.6.5 Long-Term Inputs 

As figure 57 illustrates, deflection spalling of the pavement is caused primarily by heavy wheel 

loading (with respect to the structural capacity of the pavement). These wheel loads cause the pavement 

joints/cracks to deflect and the top edges of the adjacent slabs to press together, thus producing significant 

compressive stresses causing crushing in the top layer of the slab. 

Centerline

Deflected Slabs

Figure 57. Schematic of deflection spalling mechanism. 

The mechanism behind deflection spalling is shown more clearly in figure 58. The compressive 

stresses crush the concrete at the joint/crack. The severity of the distress is controlled by the pavement’s 

deflection at the joint/crack (δ). 

Compressive stresses

Deflection spall

δ

Figure 58. Schematic of deflection spalling mechanism. 

If the joint/crack width is kept tight and incompressibles kept out, deflection spalling can be 

minimized. The tight joint/crack will maintain the load transfer, and the deflection will be reduced. 

Another way to alleviate the severity of deflection spalling is to use a subbase with low deformation 

properties, such as a stabilized subbase. Heavy wheel loads would not have as great an impact with tight 

joints/cracks and stiffer subbases. 
60 

4.6.6 Distress Prediction 

A photograph of deflection spalling is shown in figure 59. It can be seen that the top layer of 

concrete on both sides of the adjoining slab edges has spalled off. These spalls are deep, sometimes 76 

mm or deeper. In this case, aircraft have generated the heavy loads required for deflection spalling to 

occur. 

Figure 59. Photograph of deflection spalling on a CRCP. 

4.6.7 Long-Term Performance 

The rate of spalling increases with time, as shown in figure 60. Over time, and with increased 

traffic loadings, microcracks form in the concrete to reduce its strength and durability. After the critical 

number of loads has been reached, the concrete will crush and deflection spalls will form. % Spalled Joints/Cracks

Cumulative Load Applications

Figure 60. Schematic of percent JPCP spalled joints/cracks vs. time. 
61 

4.7 PUNCHOUTS 

Punchout distress is a condition that usually occurs in CRCP pavements between closely spaced 

cracks. Loss of aggregate interlock at the cracks, a function of crack width and traffic loads, can cause 

the slab to act as a cantilever beam, inducing high transverse (perpendicular to the direction of traffic) 

tensile stresses at the surface. Depending on the magnitude of the tensile stresses, strength and fatigue 

characteristics of the concrete, and traffic load applications, a longitudinal crack may eventually form 

between transverse cracks (CRCP transverse crack development is described in section 2.3). The result is 

a punchout. Progression of the punchout distress continues with traffic loads and climate cycles that 

induce spalling at the cracks, further loss of support, pumping, reduced subgrade support, and increased 

severity of the punchout distress.(15) 

This section describes the mechanisms involved in the development of punchout distress, 

primarily early-age factors such as crack spacing and crack width. A schematic representation of these 

mechanisms and the processes involved is presented in figure 61. 

1. Early-age inputs

6. Distress

3. Early-age response

4. Pavement behavior

5. Long-term inputs

Stress development

• Crack spacing.

• Crack width.

7. Long-term 

performance

History of punchouts

N

2. Materials characterization

Strength/stiffness

development

Punchouts

• Pavement design: % steel, thickness.

• Materials and mix design: CTE, HOH.

• Climatic conditions.

• Time of day of construction.

• Traffic loads.

• Climate.

• Subgrade support.

• Load transfer.

• Stress / strength ratio for 

fatigue.

1. Early-age inputs

6. Distress

3. Early-age response

4. Pavement behavior

5. Long-term inputs

Stress development

• Crack spacing.

• Crack width.

7. Long-term 

performance

History of punchouts

N

2. Materials characterization

Strength/stiffness

development

Punchouts

• Pavement design: % steel, thickness.

• Materials and mix design: CTE, HOH.

• Climatic conditions.

• Time of day of construction.

• Traffic loads.

• Climate.

• Subgrade support.

• Load transfer.

• Stress / strength ratio for 

fatigue.

Figure 61. Flowchart outlining impact of early-age input on long-term punchout distress of CRCP. 
62 

Initially, during pavement construction, early-age inputs such as materials, climate, and 

construction procedures (step 1) affect the strength, stiffness (step 2), and stress development in the 

pavement (step 3). The interaction of strength, stiffness, and stress development will lead to formation of 

cracking patterns (step 4) that will vary according to materials properties, climate, and design factors. 

The spacing and width of the cracks that form are determining factors in the magnitude of the stresses that 

later generate as a function of traffic loads, climatic cycles, load transfer, subgrade support, and concrete 

fatigue characteristics (step 5). Eventually, longitudinal cracks may form that will create an isolated piece 

of slab commonly referred to as a punchout (step 6). Progression of punchout distresses with time will be 

a function of the evolution of the cracking patterns and long-term inputs with time (step 7). A more 

detailed discussion about each one of the processes contributing to punchout development is provided in 

the following sections. 

4.7.1 Early-Age Inputs 

Early-age inputs that contribute to punchout formation are typically those inputs that affect the 

crack spacing, crack width, and steel stress during the early age. These factors include coarse aggregate 

type, steel reinforcement details, placement temperature, placement season, curing procedures, time when 

crack occurs, slab thickness, and subbase type. 

4.7.2 Material Characterization 

The strength development in the concrete is important in preventing punchout distresses. The 

strength at the cement-aggregate interface directly influences the load transfer achieved through aggregate 

interlock. On the other hand, the strength of the concrete will govern the formation of cracks due to 

tensile stresses. In the same manner, the elastic modulus or stiffness of the concrete will directly affect 

the level of stresses that develop. 

4.7.3 Pavement Response 

As described in chapter 2, volume changes resulting from temperature and moisture variations 

induce significant stresses in the concrete primarily as a function of the difference in the CTE of steel and 

concrete, the concrete drying shrinkage, the slab curling and warping, and the restraints imposed by the 

steel and the subbase. 

4.7.4 Pavement Behavior 

As a consequence of the tensile stresses that develop in the concrete, transverse cracks tend to 

form to relieve the stresses. Important characteristics of these cracks are the crack spacing and crack 

width, because they govern the stresses that develop in the long term as a function of traffic loads and 

climatic conditions. 

4.7.5 Long-Term Inputs 

In the long term, factors such as joint load transfer, traffic loads, climatic cycles, and subgrade 

support interact with the initial crack spacing and crack width to determine the level of stresses that 

develop in the CRCP. With time, the initial crack spacing will continue to change as a function of the 

combined effect of temperature fluctuations, drying shrinkage, and traffic loads. The crack width that 

initially may govern the load transfer through aggregate interlock also will change with time as a function 

of drying shrinkage, temperature fluctuations, and newly formed cracks. 
63 

As figure 62 conceptually demonstrates, the interaction of crack spacing and crack width with 

long-term factors will govern the level of tensile stresses that develop. For long crack spacings, the 

bending stresses that generate at the edge due to wheel loads are higher than for short crack spacings. 

However, the stress tends to reach a maximum at a relatively long crack spacing, and it remains at that 

level even for longer crack spacings, if all factors are the same (see figure 63). On the other hand, short 

crack spacings generate significant bending stresses in the transverse direction. The load transferred in 

the longitudinal direction across transverse cracks will depend on the moment transfer and aggregate 

interlock that, in turn, are a function of crack width as well as the dowel action produced by the 

reinforcing steel.(20) 

Rebar

σy (transverse stresses)

σx (longitudinal stresses)

Short

crack 

spacing

Long 

crack 

spacing

Direction of 

traffic

Rebar

σy (transverse stresses)

σx (longitudinal stresses)

Short

crack 

spacing

Long 

crack 

spacing

Direction of 

traffic

Figure 62. Schematic of position of tensile stresses in CRCP. 

Stress, 

σ

Crack 

spacing

σx

σy

Longitudinal

Transverse

Stress, 

σ

Crack 

spacing

σx

σy

Longitudinal

Transverse

Figure 63. CRCP longitudinal and transverse stresses in CRCP as a function of crack spacing. 

4.7.6 Distress Prediction 

Eventually, load transfer at transverse cracks is reduced due to traffic and temperature 

fluctuations. That is, the loss of load transfer reduces the capacity of the pavement to distribute load 

across transverse cracks (longitudinal direction). As a result, the slab between short cracks will tend to 

act as a beam with the longer dimension in the transverse direction, producing high bending stresses in the 

slab. The deflection produced by wheel loads thus tends to increase, aggravating the loss of aggregate 

interlock. In addition, the repeated action of traffic and precipitation, combined with subbases prone to 

erosion, may weaken the support provided by the subgrade. Depending on the strength and fatigue 
64 

characteristics of the concrete, subgrade support, loss of load transfer, and load applications, longitudinal 

cracks interconnecting closely spaced transverse cracks form and lead to what is commonly known as a 

punchout distress. This is illustrated in figure 64. 

4.7.7 Pavement Long-Term Performance History 

At every individual punchout location, the isolated piece of slab between transverse and 

longitudinal cracks will eventually continue to deteriorate, inducing spalling at the cracks. Reduced 

subgrade support and loss of load transfer may also result. In advanced stages of punchout distress, the 

traffic applications, combined with loss of support, load transfer, and pavement stiffness, rupture the steel 

reinforcement. Corrosion also causes steel rupturing, which can contribute to a significant reduction in 

the cross-sectional area of the reinforcement.(18) 

The number of punchout distresses commonly increases with time. Faulting progression for a 

typical CRCP section is shown in figure 65. Faulting progression is a function of the continuing pumping 

of the subbase materials, loss of aggregate interlock, concrete strength and fatigue characteristics, traffic 

applications, and climatic conditions. 

Figure 64. Typical CRCP punchout distress. 
65 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

012345678

Traffic-Cumulative 80-kN Equivalent Single Axle Loads (x106)

Punchouts and Patches (per km)

Figure 65. CRCP punchout progression with time. 

67 

CHAPTER 5. HIPERPAV II INPUT PARAMETERS 

This section discusses input parameters that influence the early-age behavior of JPCP and CRCP. 

This section will also outline general guidelines for designing and constructing these pavement types. 

Inputs to these guidelines are divided into the following five basic categories; these are discussed in the 

following sections. 

1. Pavement Design—These inputs often are selected in the preconstruction phase based on 

factors such as structural capacity. However, some of these inputs can be adjusted, possibly 

up to the day of construction. 

2. Materials and Mix Design—PCC is a combination of aggregate, cement, water, and other 

additives. To achieve the desired concrete performance, the type and proportioning of these 

components can be modified. This section discusses how these factors control concrete 

behavior. 

3. Climate—Climatic conditions are often the most unpredictable and uncontrollable inputs that 

affect pavement performance. The user must consider the high variability of climatic 

conditions and understand the sensitivities of the results as a function of these factors. 

4. Construction—Construction inputs sometimes can be specified to meet the specific needs of 

the project. Typically, modifying these are less expensive than modifying other 

nonconstruction-related variables. Construction practices can affect the long-term 

performance of the pavement significantly. 

5. Traffic Loading—Over time, pavements are subjected to increased traffic loading. The 

pavement should withstand the designed traffic loading. These guidelines discuss how traffic 

loading is considered in long-term pavement performance. 

The following sections detail the specific recommendations and guidelines for input selection in 

each of the five categories. Because these guidelines provide only general guidance for selecting the 

input parameters, the user must exercise sound judgment when selecting the final input parameters. To 

make the final decision, other factors such as economics, material availability, and ease of construction 

also should be considered. These guidelines are not intended to optimize the decision process, but they 

do provide a means by which to predict the success or failure of a particular combination of inputs to the 

overall performance of a JPCP or CRCP. 

5.1 DESIGN INPUTS 

Pavement design parameters typically are selected before construction based on the project site 

location. Factors such as type of subbase to be used can significantly impact both the early-age and longterm performance of the JPCP and CRCP. Other design parameters, such as thickness, drainage, and joint 

spacing (if applicable) also have an influence on the pavement’s long-term behavior. 
68 

5.1.1 Pavement Type 

Four general types of PCCP are constructed today. JPCP is the most common. Its transverse joint 

spacings are typically 4.5 to 6 m, and it contains no slab reinforcement. If a crack occurs at midslab, only 

the aggregate interlock will transfer load across the joint. Jointed reinforced concrete pavement (JRCP) is 

another type of pavement. Its transverse joints are longer, with spacings typically between 12 to 30 m. 

This pavement is reinforced at midslab, allowing for the longer joint spacing. Cracks can occur midslab 

where the reinforcement holds the pavement together, providing load transfer efficiency. CRCP does not 

have transverse contraction joints. It is heavily reinforced, and this reinforcement holds the cracks closed 

that do form. The last type of pavement is prestressed concrete pavement (PCP). It is constructed using 

the prestressed concrete girder ideology—by applying a compressive stress via post-tensioned cables to 

the pavement, it can resist greater loads, and thus may be constructed with a smaller cross-sectional area 

and longer spans. FHWA and the Texas Department of Transportation (DOT) recently have sponsored 

some recent pilot sections in Georgetown, TX, for using precast PCP in rapid construction projects, and 

additional work is underway for implementation of this technology in other States.(45)

Of these four pavement types, JPCP comprise the greatest number of new and existing concrete 

pavements. CRCP is increasingly popular due to the minimum maintenance required, but only accounts 

for a small fraction of the lane-miles of concrete pavement. PCP and JRCP are not as commonly used as 

the other types. Only JPCP and CRCP will be discussed further in these guidelines. 

5.1.2 Thickness 

Thickness design of JPCP or CRCP usually is based on long-term pavement performance 

requirements. Traffic-induced loading can lead to fatigue and other forms of cracking, spalling, and 

faulting. Each of these distress types can be controlled to different degrees by specifying a thicker cross 

section. In general, a thicker pavement will lead to a lower potential for early-age and long-term damage. 

For CRCP, the thickness of the slab is believed to affect crack width. Thicker pavements tend to 

result in smaller crack widths. A possible explanation for this behavior may be that thicker pavements 

have less exposed surface in relation to their volume than thinner pavements. As a result, thicker 

pavements are less affected by drying shrinkage.(16,19) With respect to crack spacing, thicker slabs provide 

a higher stiffness to the pavement, thus reducing the level of deflections at which the pavement is 

subjected due to wheel loads. Thinner slabs, on the contrary, are subjected to larger deflections, and 

therefore higher stresses develop, contributing to the development of additional transverse cracks, thus 

reducing the crack spacing. 

5.1.3 Joint Spacing 

In these guidelines, joint spacing is a design input only for JPCP. At early ages, joint spacing 

controls the amount of stresses that accumulate in the pavement. The joints relieve the thermal and 

frictional interface stresses by allowing controlled cracks to form. Joint spacing is also a significant 

factor that influences the joint opening size. At later ages, joint opening determines the load transfer 

efficiency of the aggregate interlock across the joint. Joint sawing (and dowels, if used) are costly, so a 

tradeoff between cost and allowable stress level usually occurs in the selection of the optimal joint 

spacing. 
69 

5.1.4 Reliability 

Reliability is a measure of design (or system) effectiveness based on the variability of each 

individual component. Each of the input parameters identified in this study has a different degree of 

variability associated with it. Reliability concepts are used to reduce the individual variabilities to a 

system reliability. By selecting a certain level of reliability, the user is, in essence, selecting the 

confidence level of the analysis and an acceptable level of risk. For example, if a reliability of 95 percent 

is selected, the user is willing to accept a 1 in 20 chance (5 percent) that the results obtained using these 

guidelines will be outside the bounds of what is predicted (unconservative). By selecting a higher level of 

reliability, the odds decrease. However, the higher the reliability, the more conservative the design may 

become, making it cost prohibitive. 

The user should select the optimum reliability level based on the function and importance of the 

facility. For low-end facilities, such as streets or local roads, a lower degree of reliability may be chosen 

(50 to 85 percent). For primary or interstate highways, a higher degree of reliability should be selected 

(90 to 95 percent). 

5.1.5 Drainage 

Water drainage from pavement layers is extremely important if the pavement is to provide 

suitable long-term performance. Excess water, in combination with heavy traffic loads, can lead to early 

distress of the pavement structure, such as faulting, transverse cracking, and corrosion of steel elements 

(dowels and steel reinforcement). Water can also reduce the strength of unbound granular subbases and 

subgrade soils. Water causes pumping and erosion of material from under the slab, and results in loss of 

pavement support. For CRCP, crack widths should be kept less than 0.5 mm to prevent water 

infiltration.(2) Pooling of the water between the slab and the subbase also can cause concrete deterioration 

that leads to spalling, especially in frost-susceptible regions. The effect of water on pavement properties, 

and its affect on the structural capacity of the pavement, must be considered when predicting the longterm behavior of JPCP and CRCP. 

For pavements, three different drainage systems are commonly used: 1) surface drainage; 2) 

groundwater drainage; and 3) structural drainage. These drainage systems are designed to drain water as 

quickly as possible away from the pavement system. The design of all important highways should 

consider the use of a drainage layer in the pavement structure. 

5.1.6 Support Layers 

There is commonly an engineered subbase course beneath JPCP and CRCP pavements. A 

subbase is typically a layer of granular or stabilized material. The subbase layer imposes restraint to 

volume changes occurring in concrete pavement during the early age. The restraint is the result of 

friction, adhesion, and bearing stresses that develop as a function of the subbase materials and 

construction procedures. For CRCP during the early age, the bond strength of the concrete to the steel is 

still weak, and the frictional restraint plays a more significant role in the pavement. After the bond 

strength increases with time, the subbase restraint is more negligible compared to the restraint imposed by 

the steel.(46)

By selecting a subbase with minimum frictional resistance at the slab-subbase interface, restraint 

can be minimized. This reduces the stress development in the pavement at early ages. A bond breaker 

can minimize slab restraint as well as reduce the possibility for reflective cracking from high frictional 
70 

subbases such as cement stabilized or hot-mix asphalt (HMA) subbases. Typical values of slab-subbase 

friction for various subbase types can be found in the HIPERPAV II software. 

The type of subbase used has been found to influence the long-term performance of the pavement 

significantly. The subbase should be chosen to allow for optimal water drainage away from the slab. If 

water cannot drain, the concrete at the joint can deteriorate, and spalling damage is more likely in the long 

term. The amount of faulting is also related to the ability of the subbase to drain. In the presence of 

water, fines can pump underneath the slab, increasing the potential for faulting. On an impermeable 

subbase, such as cement-treated base, the pumping of fines underneath the slab on one end and the 

erosion of fines at the end of the other slab can lead to a loss of support, which can result in transverse 

cracking. These distresses can be prevented or delayed if the subbase provides good drainage. Good 

drainage is one of the most efficient ways to prevent pumping.(15)

The properties of the subgrade influence the long-term behavior of the pavement, especially in 

seasonal frost areas (see section 5.3.2). In these regions, the subgrade’s resilient modulus varies 

significantly with changing seasons. Different subgrades are affected differently by effects such as thawweakening. Well-drained sandy soils tend to have a higher bearing strength, while clayey soils are 

generally weaker.(17)

5.1.7 Load Transfer 

Load transfer commonly is understood as the ability of a pavement to transfer loads across a joint 

or crack, from one slab to another. Load transfer at joints or cracks in a concrete pavement can be 

provided by aggregate interlock and mechanical devices such as dowels. When loads are applied near a 

joint or crack for a pavement with poor load transfer efficiency, significant deflections often develop. 

Good load transfer efficiency between joints or cracks greatly reduces the level of these deflections and 

stresses. The deflection and stress is reduced because the adjacent slab helps support the load. Primary 

factors known to affect load transfer efficiency include load magnitude, number of applications, slab 

thickness, joint opening, subgrade support, and aggregate characteristics.(47)

5.1.7.1 Joint Design 

JPCP pavements are susceptible to cracking due to restraint to expansion and contraction 

movements with changes in temperature and moisture. Transverse and longitudinal joints commonly are 

sawed or formed at regular intervals to control the spacing of the cracks and provide a uniform shape that 

is easier to seal against infiltration of water or incompressibles. The joint depth must be designed to 

create a weakened plane that intensifies the stresses at the joint location and therefore induces the crack to 

occur at that point. However, the depth of the joint also affects the load transfer, because the area of 

aggregate interlock through the thickness of the slab is reduced. 

5.1.7.2 Load Transfer through Mechanical Devices 

Application of loads, either by temperature or wheel loading, can be transmitted from one slab to 

the other by using dowels with JPCP or steel rebars with CRCP. Dowels in JPCP allow slabs to expand 

and contract while restraining the vertical movement from one slab to the other to avoid faulting. With 

CRCP, the expansion and contraction of the slabs is restrained by the steel to keep the cracks tight. 

Although steel is not designed for load transfer, the steel restrains the vertical movement of CRCP, thus 

reducing stresses. Cyclic loadings commonly cause crushing of the concrete particles at the dowel 
71 

interface due to the high compressive stresses that develop at those locations. Eventually the dowel 

becomes loose, because voids are created around the dowel as the crushed concrete particles are removed. 

5.1.7.3 Load Transfer through Aggregate Interlock 

In the absence of dowels, aggregate interlock can provide load transfer at the joints and cracks. 

Aggregate interlock is primarily a function of the characteristics of the aggregate, including aggregate 

size, angularity, and abrasion. In a controlled laboratory study, Nowlen investigated the effect of 

aggregate characteristics on load transfer.(13) Major findings from that study included: 

• Larger maximum aggregate size and aggregate angularity improved load transfer efficiency, 

especially for wider joint openings. 

• Load transfer efficiency decreases with cumulative load repetitions; however, aggregates with 

increased hardness maintained a higher load transfer efficiency. 

The loss in load transfer efficiency with application of loads has been corroborated by 

McCullough et al. in a load transfer study on CRCP.(2) 

5.1.7.4 Effect of Joint/Crack Width on Load Transfer 

The width of the contraction joint or crack plays an important role in the load transfer efficiency 

provided by aggregate interlock. Nowlen developed a looseness factor, which is a function of aggregate 

size and joint opening.(13) In his study, he showed that wider joints correspond to less effective load 

transfers provided by the aggregate interlock. In the study performed by McCullough et al., a reduction in 

load transfer efficiency in CRCP was also found with larger crack widths.(2) 

5.1.8 Reinforcement 

Primary steel properties known to influence CRCP transverse cracking include the percent of 

longitudinal steel, bar size, and vertical location of longitudinal steel with respect to slab thickness. 

5.1.8.1 Percent of Longitudinal Steel 

An increase in percent of longitudinal reinforcement will increase restraint. As the level of 

restraint increases, so does the number of cracks that develop, resulting in shorter crack spacings. In 

addition, the spacing of the transverse steel is commonly a function of the amount of steel used. It is 

believed that as the amount of steel increases, the average steel stresses are reduced, producing less 

elongation of the steel, which, in turn, leads to a decrease in crack width.(16) Previous investigations have 

shown that this effect is significant for steel percentages of 1 percent or less. 

5.1.8.2 Steel Surface Area (Bar Size) 

For a given amount of steel, larger bar sizes result in less steel surface area. The average crack 

spacing decreases with an increase in ratio of steel surface area to concrete volume. A possible 

explanation to this effect is that the high tensile stresses in the steel at crack locations are transferred to 

the concrete as a function of the steel surface area and deformation characteristics of the longitudinal 

steel.(46) On the other hand, the greater the bond area, the more the steel imposes restraint to movement of 

the concrete, and therefore, tighter cracks are expected to result. However, some studies have found that 
72 

although this theory holds for limestone aggregates, the opposite trend is observed for the case of 

siliceous aggregates.(19)

5.1.8.3 Vertical Location of Steel and Number of Steel Layers 

During the early age, the concrete is subjected to differential thermal and moisture gradients 

through the depth of the slab, primarily as a function of climatic conditions and curing methods. The 

location of the steel with respect to pavement depth will affect the crack widths. For example, since 

drying shrinkage is more pronounced at the surface of the slab, placing the steel close to the surface 

maintains crack widths tight more effectively. However, adequate concrete cover also should be 

maintained around the steel. Two-mat placement has been implemented in the Texas DOT specifications 

for pavements thicker than 330 mm. This helps in maintaining optimum steel bond area to concrete 

volume ratio and also allows for steel closer to the CRCP surface, where shrinkage strains tend to produce 

larger crack widths. In HIPERPAV II, the number of steel mats is used to determine the change in 

percent steel only. As new models are available that consider the effects on shrinkage and other 

behaviors as a function of the steel depth and number of bar mats, they maybe included in HIPERPAV II. 

5.2 MATERIALS AND MIX DESIGN INPUTS 

PCC consists of three basic constituents: aggregate, cement, and water. To modify a particular 

property of the PCC, SCM and chemical admixtures can also be used. SCM include, but are not limited 

to, pozzolans, fly ash, and ground granulated blast furnace slag (GGBFS). Chemical admixtures that can 

be used include superplasticizers, water reducers, and retarders. Fiber reinforcement, synthetic or steel, is 

another additive. SCM and admixtures can often affect the early-age behavior of the PCC during the 

hydration period, especially in fast-track mixes. However, modifications of the three basic PCC 

components, both in type and content, can also affect the overall concrete performance. 

The following sections will highlight the influence of material parameters on the behavior of 

PCC, with emphasis on the fast-track mixes. 

5.2.1 Aggregates 

Aggregates are, both by volume and by mass, the largest component of a PCC mix. By volume, 

they account for 60 to 80 percent of normal weight concrete. Because of this, aggregate properties can 

significantly affect the early-age and long-term performance of the concrete. The characteristics of the 

bond between the concrete paste and the aggregate is also a significant factor on concrete performance. 

At very early ages, the bond between the aggregate and the cement mortar is not yet at its maximum. 

Failure will most likely occur in this weak zone. At this very early age, aggregate strength does not 

strongly influence concrete behavior. However, once this bond has formed, then aggregate strength has a 

greater influence on concrete strength. PCC properties typically are modeled as a weighted combination 

of the individual component’s properties. 

Chemically, aggregates are composed of one or more minerals. Aggregates typically are formed 

naturally, but they can be manmade (such as steel slags). Many aggregates can be divided into two 

general categories of calcareous or siliceous. Calcareous aggregates include limestones and dolomites. 

Siliceous aggregates include granites and quartzes. Some aggregates, particularly sands and gravels, can 

be a blend of these two types. 
73 

All other factors being equal, concrete pavements constructed with aggregates that have a low 

CTE (e.g., many calcareous aggregates) perform better than those built with aggregates with a high CTE 

(e.g., many siliceous aggregates). Higher stresses can form in the pavement because the high coefficient 

aggregates experience greater expansion and contraction from temperature changes. These higher 

stresses may produce cracks that reduce long-term performance. If an aggregate with low CTE is used, 

there is less thermal shrinkage. In the final selection of aggregate type, factors other than CTE, such as 

availability and cost, should be included in the decisionmaking process. If siliceous aggregate with a high 

CTE is the only locally available material, precautions should be taken to minimize early-age damage. 

These precautions, such as cooling the coarse aggregate before use, will be discussed in more detail in the 

following sections. 

The aggregate proportion of the mix design can also influence early-age behavior, although it is 

considered to be relatively insensitive when compared to others. However, by increasing the relative 

proportion of aggregate in the mix design as compared to the other constituents, the stiffness of the mix 

will be higher for both the plastic and solid states. Therefore, the stresses will be greater, and the 

potential for early-age damage will be greater. 

Other aggregate properties, including shape and gradation, influence the behavior of the 

pavement in the long term, as well as at early ages. In JPCP, it may be only aggregate interlock that 

transfers the load across the joints. Aggregates with an angular shape provide better load transfer across 

the joint than do round aggregates. Likewise, large aggregates are better able to bridge a joint opening, 

and hard aggregates are able to resist the joint shear stresses. The bond between the angular aggregate 

and the cement matrix is generally higher as well, often resulting in a higher flexural strength. However, 

angular aggregate can reduce workability of the fresh mix, increasing the air content during placement. 

Durability of aggregate also affects the long-term performance of pavements. Aggregate should 

resist deterioration caused by weathering, such as freezing-thawing and wetting-drying. Clay balls and 

shales should be avoided because of their susceptibility to moisture swelling. If freeze-thaw susceptible 

aggregates are near the surface of the pavement, they can expand and break out of the surface of the 

pavement. Low durability aggregates typically have a higher porosity, and are easily saturated. In 

pavements with poor drainage, saturated aggregates at the bottom of the slab can cause D-cracks to form, 

which can progress upward. 

The absorptivity of aggregate directly correlates to concrete shrinkage. Granites and quartz have 

low absorption and low shrinkage, while sandstone and slate have higher absorption and therefore have 

higher shrinkage. 

The type of coarse aggregate also has a marked effect on spalling and cracking distresses. In 

CRCP, it was found that pavement constructed with crushed limestone had less damage that those 

constructed with siliceous river gravel. Reasons for this may include the lower stiffness and better bond 

to the cement matrix in the limestone concrete. 

Primary aggregate factors known to influence the cracking characteristics of CRCP include its 

angularity, bond strength properties, the CTE, and the drying shrinkage properties. Previous 

investigations have shown how the angularity and bond strength properties of the aggregate play an 

important role in the development of tensile strength in the concrete. As cracking in CRCP form 

whenever the tensile stresses exceed the tensile strength of the concrete, the characteristics of the coarse 

aggregate type used will have an effect on crack spacing. Particularly, aggregates with increased 

angularity provide higher tensile strengths than rounded aggregates.(46) Because the coarse aggregate type 

is one of the major components in the mix, the drying shrinkage and CTE of the aggregate commonly will 

govern the contraction/expansion of the concrete. As previously mentioned, differences in the CTE of the 
74 

steel and concrete induce an internal restraint to volume changes that generates stresses in the concrete 

and therefore influences cracking. In general, coarse aggregates with a high CTE result in shorter crack 

spacings than aggregates with low CTE.(19) Some studies have also found that aggregates with low CTE 

result in smaller crack widths.(19) Drying shrinkage in the concrete is a result of several factors, including 

the w/c ratio, relative humidity, curing method, and coarse aggregate type. The resulting drying 

shrinkage will affect crack spacing, as drying shrinkage contributes to the volume changes in the concrete 

and therefore to stress development. Aggregates with higher drying shrinkage characteristics usually 

result in wider cracks and closer crack spacings. 

5.2.2 Cement 

Properties of concrete change as a function of time, primarily due to changes in the cement paste. 

This is particularly true at early ages. Because the hydration process is complex and mix specific, these 

general guidelines should be used with caution. Improper selection of the cement type can lead to a poor 

performing pavement. The four basic types of cement commonly used in paving concrete are: 

• Type I: Normal cement. 

• Type II: Moderate sulfate resistance. 

• Type III: High early strength. 

• Type V: High sulfate resistance. 

Of these, Types I, II, and III are most commonly used for fast-track mixes. Type V is only 

occasionally used for PCCP construction, in areas of high sulfate contents in the soil due to deicing salts 

or in saline environments near the sea. 

These four types of cement are all hydraulic cements that react chemically with water. This 

reaction generates heat, and for each cement type, heat is released in different quantities at different rates. 

The strength of PCC is directly related to the amount of heat generated by this chemical reaction. In 

general, Type III cement releases its heat earlier than do the other types of cement. It is a high early 

strength cement. Type V is at the other extreme. It releases heat slowly and gains strength slowly as a 

result. 

Type III cement often is specified in fast-track mixes. It allows pavements to open only a short 

time after construction. However, detrimental side effects can result. Because of the high heat generated, 

the early-age pavement stresses can be quite significant. Cracks may be noticeable as the concrete cools 

down from the maximum heat of hydration. The use of Type III cement for fast-track paving should be 

monitored carefully. In addition to Type III cements, Type I and even Type II cements have been used in 

fast-track mixes. These applications can be successful if measures are taken to maximize the concrete’s 

strength gain during pavement construction for all but the shortest opening criteria. 

In general, Type I cement is recommended in fast-track mixes, unless a very short opening 

criterion is demanded, or if Type I cement can not generate the required strength gain. When a Type III 

cement is needed, it is recommended that the time of the maximum heat of hydration be set to a different 

time as the maximum air temperature. This may require that construction takes place in the late afternoon 

or evening. Night paving is recommended in the southwest United States during the summer months, for 

example. 

The amount of cement in a concrete mix influences its early-age behavior. Large cement contents 

usually cause shrinkage problems and also produce significant levels of heat in the slab. However, higher 
75 

cement contents can improve workability and strength. However, the same two benefits can be achieved 

by adjusting the w/cm ratio, or by using admixtures. The later is recommended to improve concrete’s 

workability and strength. The w/cm ratio is defined as the mass of mix water (including free moisture on 

the aggregates) divided by the combined mass of the cement and any additional cementitious materials, 

including fly ashes, silica fume, and GGBFS. This ratio is important, as it determines the overall strength 

of the mix as well as other mechanical properties, such as creep and shrinkage. Because increasing the 

w/cm ratio generally will decrease strength, it should be kept as low as possible while still maintaining a 

workable mix. Additional information on mix design proportioning can be found in the literature. 

The different types of cement also have different long-term performance. Generally, the finer the 

cement is ground (as for Type III), the higher the strength gain at early ages, but the lower the strength 

gain at later ages. Concrete constructed using Type I cement continues to gain strength as it matures in 

the field. The finely ground cements (Type III) are less durable in the long term than are the coarser 

ground cements (Type I).(5) Likewise, higher strength concretes often have numerous cracks. 

5.2.3 Chemical Admixtures 

Several types of chemical admixtures can be added to concrete for pavement construction. 

Admixtures can be used to allow concreting in hot and cold weather conditions. The following is a list of 

the various types of chemical admixtures and how their use affects PCC mixes. 

5.2.3.1 Accelerators 

Accelerator admixtures increase concrete’s strength gain at early ages. Calcium chloride 

commonly is used in accelerator admixtures. Accelerators can be used in place of Type III cement if the 

cement is not available or is too expensive. The same cautions for using Type III cements are given for 

using accelerators. Their use can also lead to long-term durability problems associated with early-age 

high heat generation, increased drying shrinkage, reduced creep capacity, potential reinforcement 

corrosion, and scaling. 

5.2.3.2 Air Entrainers 

Air entrainers are the most commonly used PCC admixture. They entrain microscopic air 

bubbles in the concrete. A minimum level of air entrainment commonly is mandated in construction 

specifications, since it has been shown to increase concrete’s long-term durability as well as its 

workability. However, air-entrainment does reduce concrete strength, so care should be taken when using 

it, especially in hot-weather conditions. 

5.2.3.3 Retarders 

Retarders extend the concrete’s set time, reduce the rate of strength gain, and commonly act as 

water reducers. They can be useful with long haul times from the batch plant to the pour site. However, 

they can be detrimental to the concrete’s structure. Retarders can offset the increased strength gain when 

constructing in hot weather, but they are rarely used in fast-track pavements. 
76 

5.2.3.4 Superplasticizers 

Superplasticizers can reduce the amount of water required to achieve a workable concrete mix, if 

used properly. They are high range water reducers that can reduce water demand by 12 to 30 percent. 

They can be used to reduce the w/cm ratio, increase concrete strength, and expedite strength development. 

Superplasticizers are often used in fast-track mixes because of these beneficial effects under hot weather 

conditions. Typically, they are added at the construction site because the increase in workability is shortlived, from 30 to 60 minutes. 

5.2.3.5 Water Reducers 

Water reducers act in a similar manner to superplasticizers, but to a lesser extent. They reduce 

water demand at least 5 percent and can produce the desired slump. They can extend the working time of 

concrete by a couple of hours and also accelerate the concrete’s strength gain. However, they may 

significantly increase drying shrinkage, so caution must be exercised when using them. Water-reducing 

admixtures improve workability by changing the electric charge of the cement particles, which improves 

dispersion of the cement particles and makes more water available for hydration. Therefore, the 

hydration of the cement is improved, with a consequent slight increase in strength development. 

Of these chemical admixtures, air entrainers are considered to be an essential element in PCC 

(where applicable). In general, many mix designs can be developed using an air entrainer, 

superplasticizer, and possibly accelerators. These materials should be used based on past experience, 

availability, and economics. 

5.2.4 Supplementary Cementitious Materials 

Fly ash, silica fume, and GGBFS have all been shown to increase later age compressive and 

tensile strengths and/or durability of concrete (reduced permeability) when used properly. It is difficult to 

generalize the effect of SCMs on concrete properties. Each one can influence the behavior of the concrete 

differently. 

5.2.4.1 Fly Ash 

Pozzolans such as fly ash are the most common type of SCM. These minerals partially replace 

the cement, and some (particularly Class F fly ash) improve workability, reduce the heat of hydration of 

the concrete, and retard concrete’s setting time. Benefits of replacing cement with fly ash include 

improved workability and lower cement demand.(48) The strength of concrete at early ages is usually 

reduced by incorporating fly ash.(49) However, satisfactory long-term strength gains are obtained. 

Common ranges of cement replacement with fly ash are between 10 and 50 percent. In general, fly ash 

retards cement hydration, consequently retarding the strength gain. This retarding effect is more 

considerable at low temperatures. Class C fly ash possesses more cementitious properties than Class F fly 

ash due to its higher free lime content. 

5.2.4.2 Ground Granulated Blast Furnace Slag 

GGBFS is used commonly in concrete operations for economy reasons at proportions of 25 to 50 

percent by weight replacement of cement. Higher slag contents are used for durability or sulfate 

resistance. Incorporating GGBFS in the mix tends to prolong the hydration, but in the long term, strength 

increases to a satisfactory level depending on the percentage of cement replacement. The setting time of 
77 

concrete increases with the use of GGBFS.(49) Final setting of PCC can be delayed as much as several 

hours, depending on the ambient temperature and mixture proportions.(49) Significant retardation in 

setting time of the PCC has been observed for curing temperatures lower than 23 oC.(49) At temperatures 

lower than 10 oC, the strength development of GGBFS is poor, and using it is not desirable. 

5.2.4.3 Silica Fume 

Silica fume reduces the permeability of the mix and significantly increases its compressive 

strength. The use of silica fume, despite its benefits, is often limited due to reduction in workability, 

placeability, flowability, and finishability. Replacing cement with silica fume has been limited in some 

standards to 10 percent.(48) However, up to 15 percent of silica fume has been incorporated successfully 

in concrete.(49) Incorporating silica fume improves cement hydration. The development of heat of 

hydration in ordinary PCC with silica fume has been observed to be as high as that of rapid hardening 

cement alone for certain mix proportions.(9)

5.2.5 Mix Design 

Concrete mix designs should be optimized for workability, strength, economy, and other concrete 

properties before using these guidelines. Several mix designs are appropriate for concrete pavements. 

The selected design should be tailored to the specific environment the pavement will be subjected to 

during its lifetime. For concrete pavements, high early strength, high ultimate strength, and low 

permeability are all desired criteria for high-performance pavements. A number of other factors should 

be considered in mix design. 

One of the most important factors affecting the properties of hardened concrete is the w/cm ratio. 

This ratio controls the quality of the paste and therefore impacts the durability and strength of the 

concrete. The concrete is a mixture of the paste and the aggregate, so the aggregate properties and 

characteristics are very important to the concrete’s quality. Aggregate gradation and particle size, shape, 

and surface texture are all important. 

Another key factor is the concrete’s 28-day strength. The 28-day strength should be selected to 

satisfy the long-term design criteria. Proper selection can delay, or even prevent, fatigue and trafficinduced cracking. It is recommended that the highest possible strength be selected in design, balancing 

the adverse effects of high shrinkage and rapid heat generation that can result. 

Other factors, such as shrinkage, should also be accounted for during the mix design process. If 

the concrete’s paste content is too high, shrinkage cracks can form. To achieve a lower paste content, the 

gradation of the aggregate can be optimized and, in some cases, also will result in an increase in the 

strength of the mix. 

Because many of the PCC constituents can exert both positive and negative influences on the 

properties of the concrete, the engineered mix should first be verified against the numerical guidelines. If 

the mix fails this test, modifications can be made to the mix based on engineering judgment and the 

criteria outlined here. 

5.2.6 Strength and Maturity 

The strength development in concrete begins after the concrete sets. Strength develops primarily 

as a function of the w/cm ratio; cement, admixtures, and aggregate characteristics and content; the curing 
78 

temperature; and moisture state. The strength of the concrete depends on the strength of the cement paste, 

the strength of the aggregates, and the bond strength of the cement/aggregate interface. 

The rate of strength development is a function of the cement properties such as the cement 

fineness and cement compounds, along with SCM and admixtures used. In general, cements with a 

higher fineness will tend to hydrate faster and develop a high early strength, although the strength 

development at later ages may be lower when compared to coarser cements. Furthermore, it has been 

observed that fine ground cements are associated with durability problems.(5) A similar effect on the 

strength development occurs when the concrete is cured at high temperatures. A rapid strength increase is 

observed at early ages, and a less steeper strength increase is noted on the long-term strength. 

It is also important to mention the effect of moisture on concrete strength. For concrete 

pavements, pronounced moisture profiles may occur as a consequence of climatic conditions. Whenever 

the internal relative humidity in the concrete drops below 80 percent, the strength development is affected 

significantly.(6)

The primary mode of failure during early-age behavior is tensile stress; therefore, the tensile 

strength of the concrete is commonly the primary concern when evaluating the behavior of concrete 

pavements. 

Maturity information can be obtained from laboratory tests as outlined in American Society for 

Testing and Materials (ASTM) C 1074.(50) With this approach, concrete strength is predicted by relating 

the strength obtained in the laboratory to a particular maturity of the concrete in the field according to its 

temperature history. 

5.2.7 PCC Modulus of Elasticity 

As with strength, the hardening process of concrete contributes to its stiffness or modulus of 

elasticity. The concrete modulus of elasticity is directly related to the concrete strength, and it also 

depends on the type of aggregates and its volume in the concrete mix. In general, a higher stiffness of the 

concrete leads to higher stresses induced to the pavement. 

5.3 CLIMATIC INPUTS 

Climatic parameters typically have the greatest variability of all the HIPERPAV II inputs. Actual 

weather conditions are unpredictable, so caution should be used when selecting these inputs. “Average” 

values of the climatic input may be satisfactory for most simulations, but the user should also test the 

effect of extreme conditions. The necessary climatic data for HIPERPAV II is available from the 

National Weather Service, from the meteorological department of the local media, or from a weather 

almanac. HIPERPAV II has the added advantage of storing this information in an internal database. 

5.3.1 Early-Age Climatic Inputs 

No one has direct control over the environmental conditions at the time of construction, but 

indirect control is available by selecting the time of day and the season. Five key climatic parameters 

directly influence the early-age performance of concrete pavements: 

• Ambient air temperatures. 

• Solar radiation (dependent on cloud cover). 
79 

• Windspeed. 

• Average relative humidity. 

• Relative humidity. 

The first three parameters affect pavement temperature, and subsequently the stresses that form 

due to thermal expansion and contraction. The last two parameters (as well as the first three to a lesser 

degree) primarily influence the pavement’s drying shrinkage, and must be considered. 

Cloud cover is a necessary input to the guidelines. The cloud cover corresponds to the solar 

radiation and heat that the pavement is subjected to at the time of construction. The cloud cover can be 

estimated based on the knowledge of regional weather patterns for the specific construction season. For 

hot weather, sunny is the critical condition, compared to partly cloudy and overcast. On the other hand, 

overcast conditions may be more critical during cold weather concreting, as this condition may affect the 

strength gain. Again, these inputs can be pulled from the electronic database in the HIPERPAV II 

software. 

Windspeed also influences early-age pavement behavior. Wind can cause convective cooling of 

an unprotected or minimally protected pavement. This can contribute to undesirable behavior, such as 

thermal shock. In addition, high windspeeds remove moisture from the surface of the pavement, 

increasing the potential for excessive shrinkage. Measures can be taken to reduce the effect of wind by 

various curing methods, such as blankets or polyethylene sheeting. 

5.3.2 Long-Term Climatic Inputs 

In the long term, influential climatic conditions are primarily: 

• Air temperatures. 

• Precipitation. 

• Freeze-thaw cycles. 

5.3.2.1 Air Temperatures 

Similar to pavement behavior at early ages, air temperatures will affect the thermal gradient in the 

slab in the long term, influencing the curling and warping stresses. Expansion and contraction of the 

concrete is also affected by changes in temperature in the long term. Slab contraction will increase the 

crack or joint width and will affect the load transfer capacity at those locations. In addition, infiltration of 

water and incompressibles are more likely to occur at wider cracks or joints. 

5.3.2.2 Precipitation 

The effect of precipitation on pavement performance will depend, in large part, on the efficiency 

of the pavement drainage. Water from rainfall usually infiltrates through cracks or joints, shoulders, and 

pavement edges. The presence of water in the pavement, combined with the repetition of heavy loads, 

commonly results in the pumping of fines, degradation of subbase material, and loss of support, thus 

affecting pavement performance. Prolonged periods of rainfall, even of low intensity, may be more 

damaging to the pavement than short periods of rainfall with high intensity. Moisture absorption by the 

soil will be more pronounced under the former condition. 
80 

5.3.2.3 Freeze-Thaw Cycles 

Frost heave in a pavement structure is a result of freezing temperatures combined with presence 

of water in the pavement, either from precipitation or other sources such as groundwater and movement 

of water table in liquid or vapor form. Frost heave is the raising of the pavement due to formation of ice 

crystals in a frost-susceptible subgrade or subbase.(51) Unlike HMA pavements, where damage occurs due 

to loss of subgrade support during frost melting, for concrete pavements, the capacity to distribute loads 

over larger areas make this type of pavement less susceptible during the thawing period.(52) However, the 

differential heave under the pavement slabs during freezing temperatures and presence of moisture at the 

subgrade increases stresses when combined with the action of traffic loads. 

The freeze-thaw action also affects the durability of concrete. During freezing temperatures, 

water in the cement paste pores tends to expand, generating cumulative damage in the concrete with time. 

Lower w/cm ratios and air entrainment admixtures generally are used in freezing areas to reduce concrete 

damage. Low w/cm ratios usually result in fewer pores in the cement paste. Air entrainment in the 

concrete provides room for the water that is freely available in the cement paste to expand during freezing 

temperatures. 

5.4 CONSTRUCTION INPUTS 

Factors affecting the moisture or temperature state of the concrete pavement during construction 

will also affect its early-age behavior. Construction methods for JPCP and CRCP provide some of the 

most critical parameters that influence the pavement’s early-age behavior and long-term performance. 

They are also the most flexible parameters, because these factors often can be modified onsite. This can, 

in most cases, prevent early-age damage and ensure a long-lasting pavement. In this section, five 

construction issues are discussed: curing, time of day of construction, initial PCC mix temperature, 

sawcutting methods and timing, and initial subbase temperature. 

5.4.1 Curing 

Curing methods and timing usually affect the development of concrete stresses and strength. 

Curing procedures control the moisture loss in the pavement, affecting drying shrinkage stresses. In 

addition, moisture loss due to poor curing conditions can decrease concrete strength. Several curing 

methods are readily available for PCCP construction. Selecting the proper curing method is key to 

constructing a high-performance concrete pavement. Because of the complexity of the pavement 

construction process, sound judgment should be used in addition to the general recommendations made 

here. 

The most common curing method is the application of a liquid membrane, which is commonly 

white. The purpose of this type of curing compound is to minimize shrinkage cracking by minimizing 

excess moisture loss through evaporation. One of the two common methods of applying this type of 

compound is using a sprayer bar, which traverses the width of the pour and applies the membrane by 

sprayer jets evenly spaced across the pavement width. The second method is using a wand or other handheld device, which is directed by human control. Neither of these application methods is fail-safe. The 

application rate is usually uneven, subjecting some areas of the pavement to greater moisture loss than 

others. A liquid membrane is beneficial in minimizing moisture loss, when used correctly. A double or 

triple application of liquid membrane can lead to an even lower potential for moisture loss-related 

distresses (e.g., plastic shrinkage cracking). 
81 

A second type of curing method is polyethylene sheeting. If used properly, this method is very 

beneficial in retaining moisture. By applying the sheeting, the moisture is trapped beneath the nearly 

impervious layer. This minimizes evaporation, thus drying shrinkage. However, if the sheeting is not 

securely fastened to the surface by edge weighting, wind can enter through the openings and increase the 

potential for early-age damage. In addition, because the sheeting cannot be placed until the PCC has 

hardened enough to sustain the disturbance from the sheeting application, a liquid membrane is usually 

applied first, with the sheeting placed later. Polyethylene sheeting also acts as a thermal insulator. This 

property can be beneficial if the construction site is subjected to rapid cooling following construction. 

However, it can be detrimental if used improperly. The insulation, in concert with the excess heat 

produced by fast-track PCC mixes, can result in too great a curing temperature, causing damage after 

placement. 

Cotton mats or burlap are the third most common curing method used on PCC pavements. The 

benefits of this method are similar to that of polyethylene sheeting. However, in addition to blocking 

moisture loss, the cotton mats or burlap are usually wetted, providing free moisture that may counter the 

negative effects of drying on the surface of the slab. The cotton mats or burlap also serve as thermal 

insulators, so they are subject to the same benefits and drawbacks described for polyethylene sheeting. 

The thinner the pavement, the more critical is the curing of the pavement, such as for overlays or 

whitetopping. The effects of drying shrinkage are limited to the surface; therefore, the large surface area 

of bonded concrete overlay (compared to the volume of concrete) subjects it to a greater sensitivity 

towards moisture loss than full depth paving. This, coupled with the greater heat loss, increases the 

probability of delamination or other types of early-age distress. Using an insulating curing method such 

as polyethylene sheeting, cotton mats, or burlap can minimize these distresses in many instances. 

5.4.2 Time of Day of Construction 

Unpredictable climate conditions at the time of construction can create a high level of uncertainty 

in the pavement’s early-age behavior. However, the time of construction can be controlled, which can 

help offset some climatic uncertainty. By adjusting the time of day of construction, the pavement’s 

temperature buildup due to hydration can be controlled. The concrete’s strength gain can be maximized, 

and the pavement’s early-age damage can be minimized. This control is especially critical for fast-track 

mixes. However, other factors, such as traffic, will often dictate construction schedules. Adjusting the 

time of construction should still be considered as a relatively inexpensive way to minimize early-age 

pavement damage. The optimal time of construction for hot and cold weather concreting is discussed 

below. 

For hot weather concreting (ambient temperature greater than 32 °C), paving in the early evening 

and into the night generally is recommended. Delaying the time of paving to evening takes advantage of 

nighttime cooling. This offsets the concrete’s heat gain during hydration. The subsequent warmup the 

following day also counters the effects of thermal shock, caused by the loss of hydration heat. This 

strategy minimizes early-age damage and also means that construction will take place during off-peak 

traffic periods. The user costs associated with construction will be minimized. 

For cold weather concreting (mean daily temperatures less than 4 °C for 3 successive days), early 

morning paving is recommended. Construction in the early morning takes advantage of daytime solar 

radiation and heat generation to promote increased concrete strength. Cold weather retards the rate of 

hydration as well as the concrete’s strength gain. For this method of construction, insulating curing 

methods such as cotton mats and/or polyethylene sheeting should be used in the evening for heat 

retention. This will minimize early-age damage. 
82 

5.4.3 Initial PCC Mix Temperature 

The temperature of the air during construction, the hydration characteristics of the cement, and 

the subsequent increase or decrease of the air temperature after placement all govern the concrete set. 

The development of stresses in the concrete is a function of the temperature at set and the subsequent 

temperature changes. As a general rule, the most critical placement time is that which results in a peak 

temperature due to hydration of the cement coinciding with the maximum air temperature during the day. 

When the pavement is placed at higher temperatures, larger temperature drops are expected. Therefore, 

higher stresses in the concrete develop. 

Because concrete temperature control is critical in constructing high performance pavements, the 

initial mix temperature is important. Several methods have been developed in the past to reduce its 

temperature by cooling one or more of the mix ingredients. Five of them are discussed below. The 

influence of cooling each ingredient on the mix temperature is related to the temperature, specific heat 

and quantity of each material. These techniques can be used during hot weather concreting. 

1. Cooling Concrete with Chilled Mixing Water—Chilling the mix water effectively reduces 

the temperature of the concrete mixture. It is also one of the concrete materials that is the 

easiest to cool. Because the amount of chilled water cannot exceed the amount of mix 

water, this method can reduce the concrete’s temperature a maximum of 5 °C. Chilling the 

mix water requires a sizable initial investment in mechanical refrigeration equipment and 

insulated water storage tanks, unless other chilled water sources are available, such as 

groundwater sources. 

2. Using Liquid Nitrogen to Cool Mix Water—Another method used to cool mix water is to 

inject the water storage tank or feed line with liquid nitrogen. This method can reduce the 

concrete’s temperature by as much as 10 °C. The cost of installing and supplying a liquid 

nitrogen supply vessel must be considered. 

3. Cooling Mixed Concrete with Liquid Nitrogen—A cooling technique related to the one 

described above is to directly inject liquid nitrogen into the concrete mixture. This method 

provides one of the most effective means to utilize the cooling capacity of liquid nitrogen. It 

can reduce the mix temperature by 10 °C. It requires installing a liquid nitrogen supply 

vessel and an injection nozzle at the central mixers. Because this method is relatively 

expensive, its benefits must be carefully weighed against cost in fast-track concrete 

pavement projects. 

4. Cooling Concrete with Ice—Adding ice to concrete’s mix water can reduce the concrete’s 

temperature by 10 °C, and it is more effective than chilled water in reducing this 

temperature. However, the actual temperature reduction is limited to the amount of cooled 

mixing water the concrete batch can accommodate. At the time of mixing, the ice must be 

weighed separately, because it has a different specific gravity from water. Block ice is a 

suitable alternative, but it must be crushed before addition. The heat of fusion of the ice also 

must be considered when calculating the final temperature of the mix. Using ice to cool 

concrete requires a large capital investment and may only be applicable when mixing occurs 

during transit. 

5. Cooling of Coarse Aggregate—Another method commonly used to cool concrete is to cool 

the coarse aggregate. This can be done by spraying cool or chilled water onto the aggregate 

as it passes by on a conveyor belt. The water is then chilled to meet the concrete production 

requirements. To lower the temperature of the concrete mix 6 °C, the aggregate temperature 
83 

must be reduced 8 °C. The coarse aggregate should be saturated uniformly to avoid large 

variations in slump from batch to batch. Some other methods to cool the aggregate are to 

protect the stockpiles from direct sunlight, refrigerate them, or sprinkle them with water; 

these techniques can reduce the temperature of aggregate significantly. 

Reducing the temperature of the cement portion of the concrete mix is not commonly done, 

because a temperature change of 6 °C generally will change the temperature of the concrete mix by only 

0.6 °C. 

For cold weather paving, it may be necessary to heat the mix. This also can be an issue for thin 

pavements or overlays, because heat is dissipated faster from them than from newly constructed 

pavements. Some of the techniques currently used are: 

• Heating Mixing Water—Heating the mix water is one of the simplest and most costeffective ways to increase concrete temperature. Because the specific heat of water is four to 

five times greater than that of most aggregate, its ability to retain heat is much greater. The 

mix water temperature can be increased by simply mixing the hot and cold feed water lines. 

When paving at temperatures below 10 °C, it may be more appropriate to heat the mixing 

water than to use an admixture designed to accelerate the set of the paving mixture. 

• Heating Aggregate—To increase the temperature of the concrete mix, the aggregate also can 

be heated. Although this technique is less efficient than preheating the mix water, it may be 

required in extreme cold weather cases where increased strength gain is necessary. The 

recommended method for heating aggregate is to circulate steam through pipes over which 

the aggregate are stockpiled. Because of the large aggregate content in the mix, increasing 

their temperature can significantly affect the mix temperature. Steam heating the aggregate 

also is appropriate for cold weather concreting operations. 

When using HIPERPAV II, the initial concrete temperature first should be estimated based on 

past experience. If a heating or cooling method is used, the initial mix temperature should be adjusted 

accordingly. 

5.4.4 Sawcutting Methods and Timing 

Joints in concrete pavements create vertical weakening planes in the concrete pavement to induce 

the cracks along their controlled axis, thus facilitating pavement maintenance and crack sealing. To 

minimize the potential for uncontrolled cracking in a PCCP, proper joint sawing procedures should be 

established. In general, the time of joint sawing should consider the following limiting criteria: 

• The joint sawing should be performed before stresses develop in the pavement that are large 

enough to cause cracking. These stresses are the result of restrained volumetric changes from 

both temperature and moisture changes in the young pavement. 

• The joints must not be sawed until the pavement is strong enough to support the weight of the 

sawing equipment and operator, and also strong enough to avoid excessive raveling due to the 

forces introduced by the cutting blade. 

The results of various research efforts may provide the user with additional guidance in regard to 

this particular aspect of PCC construction. FHWA conducted one such research effort in 1994 that 
84 

produced guidelines for timing contraction joint sawing and the earliest loading for concrete 

pavements.(53)

5.4.5 Initial Subbase Temperature 

Ideally, the temperature of the subbase should be as close as possible to the temperature of the 

concrete when placing the concrete during cold weather concreting. The ground should not be frozen, but 

could be thawed by steaming, coving with insulation, or spreading a layer of hot sand, gravel, or another 

material. 

5.5 TRAFFIC LOADING INPUTS 

Traffic is one of the most important factors influencing pavement performance. In fact, 

pavements are designed to resist traffic and climatic loads under specified levels of safety and comfort. 

Primary traffic characteristics include load configuration, traffic volume, traffic classification, traffic 

distribution, growth rate, and traffic wandering. 

5.5.1 Load Configuration 

Vehicular loads for highway pavements are conformed with varied axle configurations, including 

single, dual, tandem, and tridem axles. The type of axle typically will depend on the type of vehicle and 

the load that vehicle is intended to carry. In addition, vehicle axles are designed to resist specific loads 

according to the pressure at the tires. The stress imparted on the pavement at the surface will depend on 

the magnitude of the load and wheel contact area. The pressure imparted by the wheel on the pavement is 

practically equal to the tire pressure. The damage to which a pavement is subjected by a traffic load will 

depend on the axle configuration and tire pressure. In addition, because the elastic modulus is influenced 

by the loading rate at which a given material is subjected, the vehicle speed is also a significant factor in 

determining damage to the pavement. 

5.5.2 Classification 

Because traffic typically consists of varied wheel configurations and loading magnitudes, it is 

common to group traffic in these terms. In particular, for mechanistic methods of design or analysis, 

different groups of axle configuration and distribution of magnitude of load per axle configuration 

(vehicle load spectra) are used more commonly to characterize traffic. Other methods of traffic 

characterization include fixed traffic or fixed vehicle methods. For fixed traffic methods, the most 

damaging load anticipated is considered for design. This method typically is used for airport pavement 

design. On the other hand, the fixed vehicle method involves considering a standard vehicle or axle load 

(typically 80-kilonewton (kN) equivalent single axle load (ESAL) for highway pavements). For this case, 

the number of repetitions of that load is considered, and traffic factors are used to convert axles with other 

configurations and load magnitudes. In more practical terms, traffic commonly is classified according to 

the type of vehicle such as automobiles, recreational vehicles, buses, trucks, and trailer trucks. This 

simple classification may provide an estimate of the axle configuration and magnitude of load per vehicle 

category. 
85 

5.5.3 Traffic Volume, Growth Rate, and Distribution 

Knowing the amount of traffic loads expected during the design period is fundamental for longterm pavement analysis. The volume of traffic expected is usually provided in terms of annual average 

daily traffic and in terms of percentage per each vehicle category. 

In addition, to predict the traffic expected for a given facility accurately, it is important to 

accurately estimate the rate of growth of traffic. For a given region, the traffic growth rate typically is 

affected by land development, construction of new facilities, economic growth, and other factors. A 

common practice of estimating traffic growth is by using methods similar to estimating the worth of 

money in the future with simple, exponential, or logistical growth functions. 

Highway pavements typically are designed according to the traffic directional distribution 

(direction with greater percentage of traffic) and lane distribution (lane with greater percentage of traffic) 

for the case of facilities with more than one lane per direction. In addition, because pavement conditions 

are different depending on the time of the day (curling and warping) and season (soil support), the 

distribution of traffic through the day and throughout the year significantly affects pavement performance. 

Traffic distribution usually depends on the type of facility in question. For example, the traffic through 

the day for a city street typically concentrates early in the morning and in the afternoon (rush hours), 

while traffic for rural roads is typically less concentrated, and rather, spread throughout the day. 

87 

CHAPTER 6. CASE STUDIES 

This section illustrates the application of the HIPERPAV II guidelines to solve realistic case 

studies. The first two case studies demonstrate the application of the HIPERPAV II guidelines in 

identifying early-age factors that affect long-term pavement performance. The last two case studies 

demonstrate the use of the HIPERPAV II guidelines in identifying early-age factors that influence the 

cracking characteristics of CRCP. Two scenarios are illustrated for each of the JPCP and CRCP case 

studies: a proactive scenario and a post-mortem scenario. 

The proactive scenario may occur during the planning, design, or construction stage of a project. 

Under this scenario, the user of the guidelines may refer to chapter 5—HIPERPAV II Input Parameters—

for the proper selection of HIPERPAV II inputs under the five categories of pavement design, materials 

and mix design, environment, construction, and traffic. Because these guidelines provide only general 

guidance with the selection of the input parameters in these categories, the user should employ 

engineering judgment in the final selection of the inputs. 

For the post-mortem scenario, the user of the guidelines may be experiencing a particular 

problem, either occurring in the early age or during the long term. For this particular case, the user may 

refer to chapter 3, Early-Age Pavement Distresses, or chapter 4, Impact of Early-Age Behavior on LongTerm Performance, according to the nature and timeframe of the specific problem. 

Under both scenarios, the user may refer to chapter 2, Early-Age Pavement Behavior, for a 

detailed understanding of the mechanisms occurring during the early age that influence the performance 

of the pavement in the long term. 

6.1 PROACTIVE JPCP CASE STUDY: TIME OF PLACEMENT 

During high temperature conditions, at what time of day should concrete be placed to minimize 

the probability of cracking? 

6.1.1 Background 

Under hot weather conditions, when air temperatures exceed 32 °C, concrete temperatures often 

increase rapidly after placement. This causes the concrete to set at a high temperature, and any significant 

cooling soon after set will produce high thermal stresses in the pavement. Cracks likely will develop and 

adversely affect pavement performance. This premature random cracking is commonly called thermal 

shock (see section 3.2). 

The contractor, Jane Q. Buildalot, is scheduled to construct a 305-mm JPCP in Austin, TX, on 

July 18, one of the hottest days of the year. Knowing that high temperatures can cause unwanted 

cracking, she reviews the HIPERPAV II guidelines to help determine the optimal time to begin 

construction and still produce a pavement with good early-age and long-term performance. The time of 

day recommended in the guidelines for construction is early evening and into the night (see section 5.4.2). 

Delaying the time of construction to evening takes advantage of nighttime cooling, thereby offsetting the 

concrete’s heat of hydration. Jane can use HIPERPAV II to solve for the exact window of time when 

paving will produce a high quality pavement at early age and also in the long term. 
 

88 

6.1.2 HIPERPAV II Analysis Strategy 

HIPERPAV II can be used to assess how changing the time of placement impacts concrete 

stresses. For this case study, the HIPERPAV II temperature database will be used to estimate the climatic 

conditions on July 18. It is anticipated that the maximum temperature will be approximately 40 oC and 

the minimum temperature 18 oC. Jane is planning to use a concrete mix specified to reach a laboratory 

28-day tensile strength of 3.2 MPa, with siliceous river gravel as the coarse aggregate. Sawcutting will 

occur at the optimal time. 

Jane has several options besides changing the time of placement to avoid excessive concrete 

temperatures. She could use Type II cements or cool the concrete mix components. For this case study, 

however, she will determine the optimal time of placement for this specific concrete mixture (Type I + fly 

ash) to minimize the probability of cracking. 

Twelve HIPERPAV II runs will be performed to determine how the time of placement affects the 

pavement stresses and the concrete strengths. The maximum stress-to-strength ratio will be determined 

for each scenario. A stress-to-strength ratio greater than 1 indicates the pavement will likely crack. A 

window of caution will be noted when the stress-to-strength ratio is greater than 1. Not willing to risk 

problems, she decides that no paving should be performed during this timeframe. 

As illustrated in figures 66 and 67, changing the time of construction shifts the concrete’s peak 

heat of hydration, allowing it to be offset from the maximum daily temperature. Figure 66 illustrates 

how the concrete temperature rises sharply when its heat of hydration coincides with the peak daily 

temperature. 

Slab Temperature

Air Temperature

60

50

40

30

20

10

0

Time (hour at midnight each day)

10am Concrete Placement

0 24 48

Slab Temperature

Air Temperature

60

50

40

30

20

10

0

Time (hour at midnight each day)

10 a.m. Concrete Placement

0 24 48

Figure 66. Typical temperature development in the slab for concrete placement at 10 a.m. 

Intuitively, it is expected that concrete placed after the maximum air temperature (6 p.m.) and 

before sunrise (5 a.m.) will offset the concrete’s heat of hydration and the maximum daily air 

temperature. This will produce the most desirable placing conditions, because it forces the peak heat of 

hydration to coincide with the minimum air temperature. The resulting temperature in the concrete will 

be low. The effect of early evening placement on concrete temperature is shown in figure 67. 
 

89 

Slab Temperature

Air Temperature

60

50

40

30

20

10

Time (hour at midnight each day)

8pm Concrete Placement

0 24 48

0

0 24 48

Slab Temperature

Air Temperature

60

50

40

30

20

10

Time (hour at midnight each day)

8 p.m. Concrete Placement

0 24 48

0

0 24 48

Figure 67. Typical temperature development in the slab for concrete placement at 8 p.m. 

6.1.3 Solution 

Jane performs multiple HIPERPAV II analyses at 2-hour intervals using a design reliability of 90 

percent. The impact of changing the time of placement during hot weather conditions on the stress-tostrength ratio can be seen clearly in figure 68. For the conditions analyzed, the window of caution is from 

7 a.m. to 5 p.m. These results clearly demonstrate how HIPERPAV II can be used to determine the best 

time of day for placing concrete to minimize the probability of cracking in JPCP. 

Under these assumed conditions, the peak heat of hydration occurs about 6 to 8 hours after 

placement. Placement at 9 a.m. should produce the worst conditions, since 8 hours later, the peak air 

temperature is reached, thereby matching and amplifying the peak heat of hydration temperature. 

After the window of caution is determined, Jane can use HIPERPAV II in an iterative manner to 

further investigate the effects of other proactive changes on minimizing the potential for cracking during 

the high-risk period of 7 a.m. to 5 p.m. The measures Jane can examine include different cement types, 

different aggregate types, cooled batching water, and base whitewashing. 

0

20

40

60

80

100

120

0 4 8 12 16 20 24

Time of Day (hrs)

Stress-to-Strength Ratio (%)

Window of 

Caution

Figure 68. Early-age stress-to-strength ratio as a function of time of placement. 
 

90 

6.1.4 Long-Term Performance 

Now that Jane has determined the most favorable time to construct the pavement to prevent earlyage failures, she wants to see how the time of placement influences the pavement’s long-term 

performance. Reviewing the HIPERPAV II guidelines, she sees that joint opening, delamination, and 

built-in curling are some of the primary early-age indicators of long-term performance. 

 Jane suspects that built-in curling will definitely play a significant role in the long-term 

performance analysis, since the concrete is being placed during one of the hottest summer months, and the 

pavement likely will set with a positive thermal gradient. According to the guidelines, this will affect 

pavement smoothness, faulting, and cracking. 

Entering the specific load transfer, construction, and traffic inputs for this project, she assesses 

long-term performance as a function of placement time at 90 percent reliability. For all of the runs, joint 

faulting is a constant 0.25 mm, and it is not affected by placement time. However, transverse cracking 

and smoothness of the pavement change as a function of the time of placement. 

Figure 69 shows that pavements placed during the window of caution have the highest percentage 

of transverse cracking in the long term at 30 years, the expected design life. The pavements placed early 

in the morning and during the night have the lowest amount of long-term damage. Similarly, she finds 

that the serviceability and ride of the pavement will be the best if she places the JPCP outside of the 

window of caution (see figure 70). 

2

3

4

5

6

7

8

0 4 8 12 16 20 24

Time of Placement (hrs)

% Transverse Cracking

Window of 

Caution

Figure 69. Transverse cracking as a function of time of placement. 

0.91

0.92

0.93

0.94

0.95

0.96

0 4 8 12 16 20 24

Time of Placement (hrs)

Ride (m/km)

4

4.02

4.04

4.06

Serviceability (PSI)

Window of 

Caution

Figure 70. International Roughness Index (IRI) and serviceability as a function of time of placement. 
 

91 

 Based on this HIPERPAV II analysis, Jane is confident that placing the pavement at night and 

during the early morning hours will result in a pavement with few early-age distresses, and that the 

pavement will perform well in the long term. 

6.2 POST-MORTEM JPCP CASE STUDY: FAULTING 

After 10 years of use, a concrete pavement is faulting. Is it possible that this behavior was caused 

by early-age factors? 

6.2.1 Background 

 The faulting of a nondoweled JCP in Austin, TX is increasing, and the engineer, Joe Q. 

Thinksalot, is determined to find out why. More specifically, he wants to see if early-age conditions may 

be a contributing factor. With the HIPERPAV II guidelines in hand, he turns to section 4.1: Faulting of 

JPCP without Dowels. He wants to connect the early-age behavior of this pavement to its long-term 

performance. The early-age joint design is cited as being one of the most influential factors. The joint 

opening of a nondoweled pavement is a function of the temperature change, joint spacing, slab-subbase 

restraint, and the load transfer efficiency. 

 Joe decides to use HIPERPAV II to help him understand how these four influential parameters 

affect JPCP performance. He will perform a post-mortem analysis on this 250-mm thick JPCP. Looking 

at the construction records, Joe finds that the slab length varied between 4.5 and 7.6 m, and that the 

pavement was constructed on a smooth asphalt concrete subbase. Additional information and 

measurements collected during a field inspection visit are presented below: 

• 28-day lab indirect tensile strength: 3.6 MPa. 

• The mix design specified a Type I cement mix with 18 percent Class F fly ash replacement. 

The aggregate used in this project is of siliceous origin. 

• The air temperature at the time of placement ranged from a high of 32 oC to a low of 16 

oC. 

• The placement time was around noon on September 1, 1995. Skies were sunny and the 

windspeed averaged 10 kilometers per hour (kph). 

• The slab was covered soon after placement with a single coat of the white curing compound. 

The initial PCC mix temperature recorded at placement was 24 oC. 

• Sawing operations occurred at the optimum time. 

6.2.2 Analysis Strategy 

 Faulting occurs in JPCP as a result of several factors. Water enters the joint in the JPCP, and the 

subbase under the pavement becomes saturated. As the truck loads pass over the joint, the loose subbase 

material pumps. It comes out of the joint and causes the difference in elevation, as illustrated in sections 

4.1 and 4.2 of this guide. 
 

92 

6.2.3 Solution 

Joe uses HIPERPAV II to examine the effect of slab length, from 4.5 to 7.6 m, and dowels on 

JPCP early-age and long-term performance. The early-age critical stresses for the 4.5- and 7.6-m slab 

lengths are shown in figures 71 and 72. As expected, the stresses in the 7.6-m slabs are higher. The 

longer slabs experience more contraction and expansion around their centerline. 

Figure 71. Early-age analysis results for 4.5-m joint spacing. 

Figure 72. Early-age analysis results for 7.6-m joint spacing. 

A long-term HIPERPAV II analysis yields the faulting results for the 4.5- and 7.6-m nondoweled 

jointed pavements shown in figure 73. The faulting of the 7.6-m slabs is approaching an objectionable 

level at 30 years. Comparatively, the faulting of the 4.5-m slabs is about 25 percent less. 
 

93 

Figure 73. Predicted faulting for 4.5-m and 7.6-m joint spacing alternatives with no dowels. 

Several design changes can be made to the JPCP to reduce its faulting. One possible alternative 

is to use dowels at the joints. Dowels are one of the most effective means to reduce faulting. The 

HIPERPAV II results demonstrate this, as illustrated in figure 74. Faulting of the pavements with dowels 

is 36 to 50 percent less than it was when the pavement was nondoweled. 

Figure 74. Predicted faulting for 4.5-m and 7.6-m joint spacing alternatives with dowels. 

6.3 PROACTIVE CRCP STUDY: SEASONAL TEMPERATURE DROP 

How does hot versus cold weather placement of CRCP influence its behavior? 

6.3.1 Background 

Cracks develop in CRCP a few hours to a few days after construction due to thermal stresses. In 

some cases, the cracks may not be apparent for 5 or 10 years, but after they do appear, they can rapidly 

progress into distresses that significantly affect the long-term performance of the pavement. Excessive 

thermal cracking often is due to high temperature differentials, excessive subbase friction, aggregates 

with high CTE/contraction, or a combination of the above. 
 

94 

6.3.2 Analysis Strategy 

In this case study, a proactive seasonal analysis is performed on a 280-mm CRCP. The engineer, 

Mary T. Rifick, wants to see the influence of summer and winter placements on CRCP performance for a 

given steel design. She knows that thermal stresses play a significant role in CRCP crack development, 

and subsequently their long-term performance. 

For guidance, Mary refers to the HIPERPAV II guidelines. In section 5.3, Climatic Inputs, there 

is a discussion on the effect of early-age and long-term climatic inputs on CRCP performance. She 

decides to perform two series of HIPERPAV II runs, one for summer placement (July 25) and another for 

winter placement (January 2) using the weather estimates contained in HIPERPAV II. Because of the 

unpredictability of actual weather conditions, she decides to adjust the posted 72-hour temperatures. She 

lowers the minimum air temperature after the critical analysis to 1 oC. 

When evaluating the HIPERPAV II analyses, Mary will examine the early-age indicators of longterm CRCP performance: crack spacing, crack width, and steel stress (described in section 2.3). She 

knows that if the average crack spacing is less than 1.1 m, it is likely that punchouts will form in the 

CRCP, decreasing its long-term performance (described in section 4.7). 

6.3.3 Solution 

To perform her analysis, Mary modifies the post-72 hour climatic data, but keeps all other inputs 

at their default values. Over time, the crack spacing decreases, as shown in figure 75. She finds that a 

winter placement yields a CRCP with a larger average crack spacing at 1 year (2.1 m) than does a summer 

one (1.7 m). This means that punchouts are not as likely to form when a CRCP is constructed in winter. 

0

5

10

15

1 10 100 1000

Time (days)

Crack Spacing (m)

Summer

Winter

 3 28 365 

Figure 75. Change in crack spacing with time for summer and winter placements. 

For both the summer and winter placements, increasing the temperature differential in the 

pavement (increasing ∆T) causes the crack spacing to decrease. As ∆T increases, the slab is subjected to 

a larger temperature change, as shown in figure 76. This means that more cracks are likely to form, 

because cracking in concrete pavements is highly influenced by temperature variations. 
 

95 

Slab Temperature

Air Temperature

Time

Temperature

Early-Age

Temperatures

Seasonal

Temperature

Drop 

∆T

Slab Temperature

Air Temperature

Time

Temperature

Early-Age

Temperatures

Seasonal

Temperature

Drop 

∆T

Figure 76. Representation of PCCP temperatures in the early age and at the lowest seasonal air 

temperature. 

HIPERPAV II takes into account the thermal processes due to the concrete’s heat of hydration, 

the curing temperature, the daily minimum temperatures, and the annual minimum temperature when 

predicting crack formation. A cumulative frequency plot of crack spacing at 1 year for the summer and 

winter placements (with ∆T = 33 oC and 12 oC, respectively) is shown in figure 77. The trend at 1 year is 

consistent: the CRCP placed in the summer has more closely spaced cracks. 

0

25

50

75

100

012345

Crack Spacing (m)

Cumulative Frequency (%)

Summer

Winter

Figure 77. Crack spacing distribution for pavements constructed during summer and winter. 

Using this HIPERPAV II analysis, Mary realizes that with proper analysis, she will be able to 

construct a CRCP with good long-term performance during the winter. If a CRCP can only be placed in 

the summer, she can modify the construction process to improve its performance. She has other options 

to control the concrete temperature, such as improving the curing method. They can be investigated with 

HIPERPAV II, as well. HIPERPAV II allows her to take the guesswork out of CRCP performance and 

helps her construct CRCP with consistently good long-term performance. 
 

96 

6.4 POST-MORTEM CRCP CASE STUDY: AGGREGATE SELECTION 

How does coarse aggregate type affect the performance of CRCP for a set of climatic conditions? 

6.4.1 Background 

Two CRCP sections, pavement A and pavement B, were placed at the same time on the same day, 

December 12, 1997. However, pavement A has been performing significantly better with fewer 

punchouts and lower maintenance costs than pavement B for the past 5 years. To determine what is 

causing this difference in performance, the engineer, Sam K. Pable, picks up the HIPERPAV II guidelines 

and looks at chapter 2, Early-Age Pavement Behavior; chapter 3, Early-Age Pavement Distresses; and 

chapter 4, Impact of Early-Age Behavior on Long-Term Performance. The early-age indicators of longterm CRCP performance are crack spacing, crack width, and steel stresses. Walking down the CRCP, 

Sam notices that the cracks are spaced closer in pavement B than in pavement A, as shown in figure 78. 

On pavement A, crack spacings are distributed between 1.1 and 2.4 m, while on pavement B, the spacing 

is less than 1.1 m in some instances. 

Pavement A Pavement A

Pavement B Pavement B

Figure 78. Illustration of differences in cracking patterns for pavements A and B. 

Further investigating the reasons behind this performance difference, Sam studies the 

construction documents to see if there is a difference in materials used or construction procedures 

followed when building pavements A and B. After studying the mix designs, the only significant 

difference he can find is that limestone aggregate was used in pavement A and that siliceous river gravel 

was used in pavement B. 

Sam decides to use HIPERPAV II to assess the behavior of a 280-mm CRCP constructed with 

concrete containing different aggregate types, namely siliceous river gravel, basalt, granite/gneiss, 

sandstone, and limestone. The climatic database in HIPERPAV II is used to estimate the temperatures at 

noon on December 12. 

6.4.2 Analysis Strategy 

HIPERPAV II can be used to understand how aggregate type affects the early-age performance of 

CRCP. The expansion and contraction of the concrete greatly depends on the coarse aggregate CTE, 

since coarse aggregate comprises about half of the concrete volume. Because temperature changes are the 

greatest in the pavement immediately after construction, its volume changes are significant at early ages. 
 

97 

Figure 79 shows how the concrete volume changes based on its CTE when it is subjected to a temperature 

drop. 

Low

thermal

coefficient

High

thermal

coefficient

Temperature = 40°C Temperature = 15°C

Low

thermal

coefficient

High

thermal

coefficient

Temperature = 40°C Temperature = 15°C

Figure 79. Illustration of difference in volumetric changes with temperature for concretes with different 

CTE. 

The CTE is especially important for pavements placed in the summer season when temperature 

extremes are high, as in Sam’s analysis. During hot weather placement, the peak ambient temperature 

may coincide with the peak heat of hydration (as in morning placements). Under such conditions, 

concrete pavements having a high concrete CTE tend to have an increased probability for early-age 

cracking, when compared to pavements constructed with coarse aggregate having a lower thermal 

coefficient. The following are the HIPERPAV II default CTE values for the selected aggregates: 

• Siliceous river gravel: 11.7 m/m/°C. 

• Sandstone: 11.2 m/m/°C. 

• Granite/gneiss: 7.6 m/m/°C. 

• Basalt: 6.7 m/m/°C. 

• Limestone: 4.7 m/m/°C. 

For each of these aggregate types, HIPERPAV II analyses are performed to determine how 

aggregate CTE impacts CRCP crack spacing, crack width, and steel stresses. It is expected that the 

aggregate with the lower CTE will yield a pavement with longer crack spacings and fewer long-term 

failures (punchouts) (see section 4.7). 

6.4.3 Solution 

Sam performed HIPERPAV II runs to assess how the aggregate types listed above influence 

CRCP performance. PCC CTE is assumed to be 20 percent higher than aggregate CTE. The impact of 

changing the aggregate CTE on crack spacing can clearly be seen in figure 80. 
 

98 

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

4 6 8 10 12

Aggregate CTE (με/°C)

Average Crack Spacing 

(m)

Figure 80. Average crack spacing after 1 year for aggregates with different CTE. 

For aggregate with a low CTE, the crack spacing is high (2.1 m), which translates to a reduced 

number of punchouts in the long term. 

Figure 81 shows the cumulative crack spacing for the pavements containing siliceous river gravel 

and limestone at 1 year. It is apparent that the average crack spacing is smaller for the pavement with the 

siliceous river gravel. 

0

10

20

30

40

50

60

70

80

90

100

012345

Crack Spacing (m)

Cumulative Frequency (%)

Siliceous river

gravel

Limestone

 Figure 81. Crack spacing distribution after 1 year for the siliceous river gravel and limestone strategies. 

From these results, Sam concluded that CRCP will have better long-term performance if the 

concrete used in its construction has a low CTE. In this case study, changing the aggregate in the 

concrete from one with a high CTE to one with a low CTE resulted in a larger average crack spacing. 

This translates to less distress in the long term. 

Sam discovered that the pavement constructed with the low CTE aggregate provides better 

performance because the thermal stresses are reduced. If low CTE aggregates are not available (as is 

often the case) and a high CTE aggregate must be used, he knows that HIPERPAV II can optimize the 

time of day and the season of placement to ensure the best CRCP performance possible. 
99 

CHAPTER 7. HIPERPAV II USER’S MANUAL 

In HIPERPAV II (software version 3.0), several changes were made to the software from the 

previous release of HIPERPAV I (software version 2.X). This user’s manual outlines those changes and 

discusses the new input needed. For information on the theory behind HIPERPAV II, refer to the 

guidelines (chapters 2 through 5). 

In HIPERPAV II, the user can now perform early-age behavior analyses for jointed concrete 

pavement, evaluate the impacts of early-age factors on JPCP long-term performance, and perform 

analysis for CRCP (see figure 82). 

Figure 82. Project type selection screen for HIPERPAV II analysis. 

The input screens for these three project types are described below. 

7.1 PROJECT INFORMATION 

After the user selects a project type in the new project window (figure 82), the software creates a 

strategy with default inputs that the user can modify with the inputs for a specific situation. 

There are two primary sections in HIPERPAV II: the project information section discussed 

below, and strategies section discussed later. 

Regardless of the project type, project information is needed for all of the HIPERPAV II 

analyses. Under the project information screen (figure 83), the user can enter general project information, 
 

100 

including the project name, project ID, section name, and beginning and ending stations. A comment box 

is also provided for any additional information. 

Figure 83. Project information screen for HIPERPAV II analysis. 

7.1.1 Geography Screen 

In the geography screen, the user can select the position within the 50 U.S. States where the 

project is located (figure 84). Historical weather data from nearby weather stations to the site can be used 

during the analysis if desired. Climatic information including air temperatures, windspeed, relative 

humidity, cloudiness, and annual rainfall conditions will be estimated based on this location from the 

nearest weather stations. Section 7.3.7 provides additional information on selecting the project location. 

To navigate the geography screen, five icons are available for use. The user can: 

 Magnify the map. 

 Decrease magnification of the map. 

 Select the location of the project. 

 Drag the map. 

 Zoom to show the entire map. 
 

101 

Figure 84. Geography screen for HIPERPAV II analysis. 

7.1.2 Monthly Weather Data Screen 

Monthly rainfall data is used for the long-term analysis only. If the user has more accurate 

rainfall data, it can be entered in the monthly weather data screen (figure 85). 
 

102 

Figure 85. Monthly weather data screen for HIPERPAV II analysis. 

7.2 EARLY-AGE JPCP ANALYSIS 

After the user selects option 1 in the project type selection screen (figure 82), and the general 

project information is entered, one or more strategies for that specific location can be created for analysis 

under the strategies section (figure 86). 

7.2.1 Strategies 

The strategies section contains, in tree view, the specific input data required to perform an earlyage JPCP analysis under the categories of: 

• Design. 

• Materials and mix design. 

• Construction. 

• Environment. 

7.2.1.1 Strategy Toolbar 

It is possible to have multiple strategies in one project. Each of the strategies can have different 

design, materials and mix design, construction, and environment inputs. 

The strategy toolbar is provided to manipulate strategies. The strategy toolbar includes the 

following commands: 
 

103 

 Add a strategy 

 Copy the currently selected strategy. 

 Delete a strategy. 

 Validate a strategy to verify that inputs are within allowable ranges. 

 Run an analysis for the currently selected strategy. 

All the above functions can also be performed by right clicking on the strategy name. 

7.2.1.2 JPCP Early-Age Strategy Information 

To perform an early-age JPCP analysis, a new strategy must be added. With the strategy created, 

the strategy information including design, materials and mix design, construction, and environment 

information can be entered. The screens where this information is entered are listed in a menu format on 

the left side of the HIPERPAV II screen. As shown on the strategy information screen (figure 86), the 

user can enter his or her name and chosen reliability level. After the strategy is run, the date of analysis 

also will appear on this screen. A comment box is available for each strategy. 

Figure 86. Strategy information screen for HIPERPAV II analysis. 
 

104 

7.2.2 Design Inputs 

Under the design inputs, the user can enter the pavement design information, including pavement 

geometry, dowel design, and slab support information. 

7.2.2.1 Geometry Screen 

Under geometry (figure 87), fields to enter the slab thickness, slab width, and transverse joint 

spacing are provided. For any input in HIPERPAV II, the user can select from several either metric or 

English units and can convert between unit systems. To convert value, check the convert value box and 

click on the desired unit. 

Figure 87. Geometry screen. 

A schematic of the geometry input entered in HIPERPAV II is shown in figure 88. The slab 

width that should be input in HIPERPAV II is the widest spacing between adjacent longitudinal joints. 

Similarly, the transverse joint spacing in the case of random joint spacings should be the largest spacing 

between transverse joints (although the user can run each joint spacing as a separate strategy to compare 

the results). 

Slab

Width

Paving Width

Longitudinal

Joints

Transverse

Joints Joint

S

Spacing houlder

Shoulder Slab

Width

Paint Stripe

Slab

Width

Paving Width

Longitudinal

Joints

Transverse

Joints Joint

S

Spacing houlder

Shoulder Slab

Width

Paint Stripe

Figure 88. Schematic of the geometry input in HIPERPAV II. 
 

105 

7.2.2.2 Dowels Screen 

The dowels design information is entered only if the user wants to evaluate the bearing stresses at 

the dowels during the early age. The dowel analysis module can assess how dowel bars affect the earlyage performance of the joint in jointed concrete pavements (e.g., how the bearing stress of the dowel on 

the concrete changes as a function of temperature and time will be calculated). If the bearing stress is 

greater than the concrete’s early-age bearing strength, then it is probable that the dowel will loosen in the 

pavement at a faster rate than if the bearing stress was designed to be less than the concrete’s bearing 

strength. Cyclic loadings, particularly during the early age, commonly cause crushing of the concrete at 

the dowel interface due to the high stresses at those locations. Voids at the dowel-concrete interface will 

eventually cause the dowel to provide reduced load transfer efficiency. 

If this module is enabled, then the dowel size, Poisson’s ratio, and modulus must be input (figure 

89). In addition, the 28-day effective modulus of dowel support is required. The modulus of dowel 

support is defined as “the bearing stress in the concrete mass developing under unit deflection of the 

bar.”(54) Additional information is required on concrete compressive strength under the PCC properties 

screen if a dowel analysis is to be performed. 

Figure 89. Dowel input screen. 

7.2.2.3 Slab Support Screen 

The slab support screen requires information on the material type directly underneath the slab 

(see figure 90). Options are provided for different subbase types or subgrade conditions (see pulldown 

menu in figure 91). Additionally, information on the subgrade stiffness in terms of modulus of subgrade 

reaction (k-value) or subgrade resilient modulus, and subbase thickness and subbase elastic modulus are 

required. 
 

106 

The k-value may be obtained by: 1) correlations with soil types and other subgrade support tests 

(i.e., CBR, R-value, etc.); 2) determination of elastic modulus of individual layers (e.g., with the use of 

deflection testing) and backcalculation methods; or 3) plate load testing methods. 

AASHTO T 274 may be used to characterize relatively low stiffness materials such as natural 

soils, unbound granular materials, stabilized materials, and asphalt concrete. Alternatively, the repeatedload indirect tensile test method ASTM D 4123 may be used to test bound or higher stiffness materials 

such as stabilized bases and asphalt concrete. The elastic modulus of base materials with a high cement 

content may be obtained with the ASTM C 469 test method. 

Figure 90. Slab support input screen. 

Figure 91. Available subbase types or subgrade conditions. 
 

107 

The axial restraint conditions can be estimated based on the layer directly underneath the slab, or 

can be user-defined with linear or nonlinear functions that best match the restraint stress-movement curve 

from field restraint tests. A restraint or pushoff test consists of casting a small slab with an approximate 

thickness of the projected pavement on top of the same subbase type. A horizontal force is applied on one 

side of the slab with a hydraulic jack and a load cell is used to measure the applied load. Dial gages are 

installed at the opposite side to measure the slab movement. The restraint stress is determined from the 

applied force divided by the area of the test slab. The testing history of restraint stress and slab movement 

during the pushoff procedure is recorded, and the restraint stress at free sliding is evaluated.(55)

7.2.3 Materials and Mix Design Inputs 

The second input category is materials and mix design. This input category includes the cement, 

PCC mix, PCC properties, and maturity data inputs. 

7.2.3.1 Cement Screen 

Under the cement input screen shown in figure 92, the user selects the type of cement either by 

ASTM cement type classification (pulldown in figure 93), user-defined oxides, or user-defined Bogue 

compounds. If selected, the user-defined oxides or user-defined Bogue compounds are entered in tabular 

form. 

Blaine fineness can be estimated from the cement type or user-defined if this information is 

available. 

Figure 92. Cement input screen. 
 

108 

Figure 93. Available cement types in HIPERPAV II. 

A help screen that explains the heat of hydration effects of different cementitious materials in 

HIPERPAV II is available in this screen (see figure 94). 

Figure 94. Heat of hydration help screen in HIPERPAV II. 
 

109 

7.2.3.2 PCC Mix Screen 

The PCC mix screen is used to enter the mix design related information (figure 95). Under the 

PCC mix screen, the user selects the type of coarse aggregate used in the mix (see pulldown menu in 

figure 96), the user can also enter the type of chemical admixtures according to ASTM C 494 (see 

pulldown in figure 97). Note that Type A and F are not included, because they would not affect the 

analysis (hover over to see tool tip). If fly ash is used, it is necessary to specify the fly ash class and 

approximate calcium oxide (lime) content for Class F (see pulldown menu in figure 98). Batch 

proportions by mass are also entered in this screen. 

Help icons are provided in several software screens to provide additional guidance on the 

proper selection of inputs. 

Figure 95. PCC mix input screen. 

Figure 96. Available coarse aggregate types in HIPERPAV II. 
 

110 

Figure 97. Available admixture types in HIPERPAV II. 

Figure 98. Fly ash class drop-down menu. 

7.2.3.3 PCC Properties screen 

The PCC properties screen includes inputs for the 28-day strength, concrete CTE, 28-day 

modulus, and ultimate drying shrinkage (figure 99). 

The 28-day tensile strength is determined through the ASTM C 496 or AASHTO T 198 splitting 

tensile test. Alternatively, the user can estimate the splitting tensile strength based on relationships with 

other strength types (see pulldown menu in figure 100). In the equations shown on the screen, “STR” is 

the PCC 28-day strength type. The splitting tensile strength (STS) is used to predict the formation of 

cracks in the early-age JPCP. The compressive strength (CS) is used to assess dowel-bearing stresses at 

early ages with the dowel analysis module. Default conversion values are provided in HIPERPAV II, 

however, the user is cautioned to develop project specific coefficients based on laboratory testing for the 

mix in study (see figure 101). 

The PCC modulus of elasticity may be determined with ASTM C 469. AASHTO T 160 test 

procedure at 40 percent relative humidity may be used to determine PCC ultimate drying shrinkage. This 

test is equivalent to ASTM C 157. The PCC CTE can be entered or estimated by HIPERPAV II based on 

the coarse aggregate CTE. The latter can be user-defined or estimated based on default values. 

AASHTO has recently developed a provisional standard that can be used for testing the concrete CTE: 

TP–60–00, “Standard Test Method for the Coefficient of Thermal Expansion of Hydraulic Cement 

Concrete.” 
 

111 

Figure 99. PCC properties screen for early-age JPCP analysis. 

Figure 100. Strength type drop-down menu. 
 

112 

Figure 101. Help icon under PCC properties screen. 

7.2.3.4 Maturity Data Screen 

The last input under the materials and mix design category is used to enter maturity data, if 

available. Two methods of maturity are provided: the temperature-time factor with the use of the NurseSaul maturity relationships according to ASTM 1074; or the equivalent age method with the use of the 

Arrhenius relationships. For either method, maturity and strength information are entered in a gridline 

and automatically plotted on the screen, as shown in figure 102. 
 

113 

Figure 102. Maturity data input screen. 

7.2.4 Construction Inputs 

The third input category corresponds to construction information (figure 103). In this screen, the 

initial temperatures of the concrete mix and support layer are entered. Information on the curing method 

used is required, as is the age at which curing is applied. The age when curing is applied is defined as the 

time elapsed from construction to the time when the slab is covered with membrane curing compounds or 

polyethylene sheeting. If removable curing methods such as polyethylene sheeting are selected, the age 

when curing is removed is required. Available curing methods are presented in the drop-down menu for 

curing method shown in figure 104. A help icon is also available in the curing method inputs, which 

includes information on the effects of curing type selection. 

Information on when joints are cut is also entered in this screen. Three sawcut options are 

available to the user: 

• Saw at optimum time: HIPERPAV assumes that as soon as the concrete is strong enough to 

sawcut, the joints are formed, and HIPERPAV performs the analysis based on the transverse 

joint spacing entered. 

• User-defined sawing age: HIPERPAV simulates the stress development for a semi-infinite 

slab until the specified sawing age. After that time, the stress development is simulated based 

on the transverse joint spacing entered. 

• No sawing: HIPERPAV simulates the stress development for a semi-infinite slab for the 72-

hour analysis. This option is useful to estimate the latest sawcutting time. The time when the 

stress exceeds the strength for this scenario would correspond to the latest sawcutting time. 

However, this option must be used with caution, since a great liability is involved. 
 

114 

Although not a recommended practice, the user may also estimate the effect of skip sawcutting 

for the first two options. Options for skip sawcutting, varying from every other joint to every fifth joint, 

may be specified in the drop-down following the “skip sawcutting every” checkbox. If this option is 

selected, the user also needs to enter the time when the skipped joints are cut. 

In addition, if a given strength for opening to traffic is required, this information can be entered in 

the construction inputs screen. Figure 104 shows the strength types that can be entered. Also, as shown 

in figure 104, a help icon for strength for opening to traffic input is provided. After the analysis is run, 

the strength for opening to traffic is indicated in the analysis screen (later shown in figure 110) if this 

strength is achieved within the 72-hour analysis period. 

Figure 103. Construction screen. 
 

115 

Figure 104. Drop-down menus and help screens under construction inputs. 

7.2.5 Environment 

The last input category corresponds to environment. Under this input category, the user can enter 

climatic conditions for the 72 hours following construction, as shown in figure 105. 

Using the HIPERPAV II environmental database, it is possible to estimate temperature, 

windspeed, humidity, and cloud cover for any location selected in the geography screen (figure 84). Or, 

if the user wishes, specific hourly weather data can be entered in the gridlines provided. The information 

displayed in this screen corresponds to the climatic input selected in the data to display drop-down menu 

shown in figure 106. 
 

116 

Figure 105. Environment screen. 

Figure 106. Drop-down menu for selection of climatic input screen to display. 

If the construction date or time are changed, it is important that all of the temperature, windspeed, 

humidity, and cloud cover inputs be estimated again using the “estimate” or “estimate all” icons to match 

the selected point in time based on the geographic location selected. “Estimate” updates only the data 

displayed on the current screen. “Estimate all” updates all the weather data under temperature, 

windspeed, humidity, and cloud cover. The “prompt to update hourly data” checkbox can be unchecked 

to automatically update weather data as a function of changes in construction time or construction date. 

Otherwise, a prompt asking to update weather data will appear whenever a change in construction time or 

date is made. 

The user also has the options to: 

• Drag individual points on the plot with the point feature (see figure 107). 

• Specify high and low values for each day by selecting the high-low feature and dragging the 

red points (see figure 108). 

• Simulate a cold front condition by selecting the “Cold Front” icon and dragging down the 

desired point (see figure 109). 
 

117 

Options for plotting weather data in terms of elapsed time from construction or for time of day 

are provided. In addition, an autoscale feature can be selected to cover a wider or narrower weather data 

range. 

Figure 107. Time-temperature distribution modified with the point feature. 

Figure 108. Time-temperature distribution modified with the high-low feature. 
 

118 

Figure 109. Time-temperature distribution modified subjected to a cold front. 

7.2.6 Early-Age JPCP Analysis 

With the input assigned, the user should save the inputs before performing an early-age JPCP 

analysis. 

After the analysis is run, a window appears showing the analysis status, and the stresses at the top 

and at the bottom of the slab are plotted along with the development of the tensile strength in the concrete, 

as shown in figure 110. 

Figure 110. Analysis screen for early-age JPCP. 
 

119 

The numerical stress and strength values also are presented. The critical stress is the largest 

tensile stress, whether it is at the top or at the bottom of the slab. The numerical value of tensile stress 

and strength can also be obtained by hovering the mouse over the point of interest. The point in time 

when the strength for opening to traffic is reached is indicated here in green (highlighted with an arrow 

and circle for clarity). 

Also, because more than one strategy can be analyzed with HIPERPAV II, comparisons can be 

made between the analysis results more easily. It is possible to toggle between the analysis screens by 

selecting one strategy and then the other one (for this, the user must have at least two strategies previously 

analyzed for comparison and toggle between them). 

7.2.6.1 Interpretation of Analysis Results 

HIPERPAV executes a series of powerful algorithms that calculate the PCC pavement stress and 

strength development continuously for the first 72 hours following placement. The user is presented with 

a graphical screen, which plots the results of the analysis as they are computed in real time. The user can 

observe the trend of the strength and stress development and assess the behavior of the pavement based 

on the specific user inputs. Following processing, HIPERPAV will then identify possible problem areas 

and inform the user that the potential for early-age damage is present with the given set of inputs. 

Figure 110 shows an output screen from a typical run that demonstrates mix design, pavement 

design, and construction during PCC pavement placement that lead to a high probability of good 

performance. The strength curve is the top curve, which remains above the stress curve at all times 

during the first 72 hours. Note the cyclical manner in which the critical stress occurs. Peaks in the stress 

curve occur at critical periods when either the axial stresses are dominant or when curling stresses are 

dominant; the former is in the early morning hours, and the latter is just after midday. In this scenario, the 

probability for PCC pavement distress (random transverse cracking) is low, because the stress does not 

exceed the strength during the first 72 hours after placement. 

Figure 111 shows an output screen from a typical run where the combination of mix design, 

pavement design, construction, and the conditions during placement are such that the probability of a 

poorly performing PCCP is significant. The inputs for this particular run differ from that in figure 110 

only by the minimum ambient temperature. A lower value of minimum ambient temperature was used 

for the scenario presented in figure 111, thus resulting in a thermal shock, which can lead to premature 

cracking. 

The objective of the HIPERPAV guidelines and the accompanying computer software module is 

to minimize damage to the PCCP during early ages (first 72 hours after placement). By following the 

general recommendations made in previous chapters of this document in conjunction with the software 

described in this manual, the chances for achieving this objective are increased substantially. 
 

120 

Figure 111. HIPERPAV II early-age analysis showing poor performance. 

7.2.6.2 Evaporation Rate Analysis 

An analysis screen also is provided for evaporation rate (figure 112). The effect of curing 

methods is not considered on the evaporation rate analysis. The evaporation rate analysis is a function of 

the windspeed, relative humidity, air temperature, and HIPERPAV II predicted concrete temperatures. 

The predicted evaporation rate is presented in both graphic and tabular form in this screen. 
 

121 

Figure 112. Evaporation rate analysis for early-age JPCP analysis. 

7.2.6.3 Dowel Analysis 

The dowel analysis screen compares the concrete bearing strength to the bearing stress generated 

in proximity to the dowels due to slab curling as shown in figure 113. Because slabs in the field may 

show different curling conditions from one slab to the other, two scenarios are considered: 1) two slabs 

with similar curling conditions (curl-curl stress); and 2) one slab flat and the adjacent slab in a curled 

shape (flat-curl stress). It is believed that the actual stress to which a concrete/dowel may be subjected 

would be intermediate between these two conditions. Like the analysis screen, the analysis results are 

presented in both a graphical and a tabular form. 
 

122 

Figure 113. Dowel analysis screen for early-age JPCP. 

7.3 JPCP LONG-TERM COMPARATIVE ANALYSIS 

The main focus of the software is in the early-age behavior of JPCP. The long-term performance 

module should be used to further optimize early-age pavement design, materials selection, and 

construction procedures. The long-term performance modeling should examine relative (strategy 

comparison) rather than absolute performance, based on early-age factors. In this way, the long-term 

module can reinforce good paving practices. It must not be used for pavement (structural) design 

purposes. 

In this section, the long-term comparative analysis of early-age strategies is demonstrated. The 

user should be familiar with the early-age JPCP analysis screens before proceeding with this section. 

After the user selects option 2 in the project type selection screen (figure 82), the software creates 

two early-age JPCP strategies with default inputs that the user can modify with the inputs for his or her 

specific situation. 

In the example in figure 114, a limestone coarse aggregate is selected for the second strategy to 

observe the impact of this change in the long term as compared to the siliceous coarse aggregate used in 

the first strategy. The strategies are automatically sorted alphabetically. After both strategies have been 

analyzed, the user can switch to the long-term analysis module by selecting “LT JPCP” under the strategy 

type pulldown menu. 
 

123 

Figure 114. Strategy type pulldown menu. 

 After generating at least two early-age JPCP strategies and performing analyses on them, it is 

possible to run a long-term JPCP analysis. 

This long-term analysis is designed to be comparative, so an early-age base strategy is selected 

and compared to the early-age comparison strategy. This allows the user to see how early-age factors 

affect long-term pavement performance. In this way, long-term performance effects can be reduced with 

the optimum selection of early-age factors. 

7.3.1 Long-Term Strategy Information 

Under strategy information, the user selects the base strategy and the comparison strategy (figure 

115). Fields for user name and comments also are provided. After the strategy is run, the date of analysis 

will appear on this screen. 

Figure 115. Strategy information for long-term JPCP analysis. 
 

124 

7.3.2 Performance Parameters 

In the performance parameters screen, the user is able to enter the long-term analysis period, the 

reliability level, and the initial roughness index (figure 116). An option is also provided to assess the 

effect of built-in curling. Built-in curling is a term used for the curling state that develops at set and that 

later influences the curled shape of the slab as the thermal gradient is subsequently modified by the 

hydration process and climatic conditions (see section 2.4.2.2). HIPERPAV II considers two slab curling 

conditions: 

• Consider built-in curling effect checkbox—unchecked: Curling stresses are computed for 

thermal gradient at time of loading only (assumes flat slab when thermal gradient is zero). 

• Consider built-in curling effect checkbox—checked: Curling stresses are computed for 

thermal gradient at time of loading plus built-in curling present at PCC set time. 

Because built-in curling relaxes with time, none of the above conditions is actually correct, but it 

is believed that the actual condition will lie between these two. During the model validation, it was 

observed that, depending on the thermal gradient built-in at set (positive or negative), considering built-in 

curling would show greater potential of cracking in some instances, and for others, not considering builtin curling would be more critical. Therefore, this option was left in the user’s control. The most critical 

case can be identified by running long-term strategies for both built-in curling and no built-in curling 

conditions at different times of placement. Long-term relaxation effects are difficult to assess at present, 

due to limitations of available models. In the future, these limitations may be overcome with the 

development of more sophisticated built-in curling models. 

In addition to the above inputs, the user can set the maximum allowable joint faulting, transverse 

cracking, longitudinal cracking, IRI, and serviceability in this input screen. These set limits are compared 

to the analysis results in the long-term analysis screen. If the analysis has predicted a level of distress that 

the user denotes as “terminating” (beyond the predefined distress threshold), HIPERPAV II reports it as 

the end of the service life for that analysis. However, the analysis continues until the analysis period is 

reached. 
 

125 

Figure 116. Performance criteria screen for long-term JPCP analysis. 

7.3.3 Joint Design 

Under the joint design the user selects weather dowels and tie bars are provided. Dowels 

reinforce the transverse joint while tie bars reinforce the longitudinal joint (figure 117). 

Note: The inputs in the early-age dowel analysis module do not apply to the long-term analysis. 

If dowels are selected as the load-transfer device in the long-term analysis, then for every strategy, dowels 

are used in the analysis, regardless if they were used or not used in the early-age analysis. 

The user can select from no transfer devices, only dowels, only tie-bars, or both dowels and tie 

bars. If dowels are selected, dowel spacing and length are required in addition to dowel size and 

modulus. If tie bars are selected, their size and spacing must be input. The transverse sawcut depth is 

also entered as part of the joint design inputs. 
 

126 

Figure 117. Load-transfer design for long-term JPCP analysis. 

7.3.4 Traffic Inputs 

Traffic loading also must be input to the long-term analysis, in addition to the strategy 

information, distress thresholds, and load-transfer design input. Five input screens are provided for this 

category: one for general traffic information, three for traffic load spectra, and one for traffic growth rate. 

7.3.4.1 General Traffic Input Screen 

In the general traffic input screen (figure 118), the mean truck tire pressure is required. The user 

can enter a user-defined traffic load spectra or have HIPERPAV II estimate the load spectra based on the 

input annual ESALs for the design lane. The default traffic load spectra generated by HIPERPAV II is 

based on typical averages of rural and urban highway traffic (see section B.2.5.4 in appendix B, volume 

III of this report series). If the user-defined option is selected, the user can enter specific single axle, 

tandem axle, or tridem axle load values in the gridlines for traffic loading. 
 

127 

Figure 118. General traffic loading screen for long-term JPCP analysis. 

7.3.4.2 Axle Load Spectra Input Screens 

If the user enters the load spectra information, this information is entered in the single axle load, 

the tandem axle load, and the tridem axle load screens (figure 119). 

For each traffic load spectra category, the number of single tire and dual tire axle loads per year 

are entered against the axle load group. The single tire, dual tire, or total load spectra per axle type is 

shown on the plot, depending on the column selected. The total number of axles per axle load group is the 

sum of the respective single tire and dual tire values. 
 

128 

Figure 119. Single axle load screen for long-term JPCP analysis. 

7.3.4.3 Traffic Growth Rate Input Screen 

Finally, the traffic growth rate information is entered in the growth rate screen (figure 120). 

Three different growth functions can be specified: linear, exponential, or logistic. Depending on the 

function selected, the input required varies. For any function shown, the traffic loading is divided by the 

base-year traffic loading and plotted against time. Two plot methods may be selected: annual or 

cumulative. 
 

129 

Figure 120. Traffic loading growth rate screen for long-term JPCP analysis. 

7.3.5 Long-Term Analysis 

With the input assigned, the user should save the project file before performing a long-term JPCP 

analysis. Icons to manipulate strategies similar to those available for early-age strategies can be used for 

long-term analyses (see section 7.2.1.1). 

After the analysis is run, a window appears showing the analysis status. The base strategy first is 

analyzed followed by the comparison strategy (figure 121). For each strategy, several structural and 

functional distresses are predicted, including: 

• Joint faulting. 

• Transverse cracking. 

• Longitudinal cracking. 

• IRI. 

• Serviceability. 

After the analysis is complete, users can now select the type of distress to plot by selecting the 

distress drop-down window (figure 122). 

Each distress type is plotted as a function of time. The distress magnitudes are presented in 

tabular format at the end of the prediction lifetime or at the time the threshold value is reached, whichever 

occurs first. 
 

130 

Using the data values plot method, absolute values of the distress are provided (see plot method 

drop-down in figure 123. If the change plot method is chosen, the change in predicted distresses between 

the base strategy and the comparison strategy is plotted. 

Figure 121. Analysis screen for long-term JPCP. 

Figure 122. Drop-down menu for distress to plot. 

Figure 123. Plot method drop-down menu. 
 

131 

7.3.6 Multiple Long-Term Comparative Strategies 

In the long-term module, if more than two early-age strategies are to be compared, this can be 

done by creating additional strategies with the strategy toolbar. Once the strategy is created, the 

additional strategies to compare are selected in the strategy information window, as previously described. 

7.3.7 Early-Age and Long-Term JPCP Analysis—Sample Scenario 

In this section, step-by-step instructions are provided to show the effect of aggregate selection on 

early-age thermal cracking potential and on long-term transverse cracking. The early-age inputs used for 

this exercise are presented in table 1. Input values in bold represent the inputs that are different for these 

two early-age strategies. 
 

132 

Table 1. Inputs for 11 a.m. and 7 p.m. times of placement strategies. 

Input Category Input Screen Input Value 

Geography Austin, TX 

Project Information Monthly Weather 

Data 

Estimate Monthly Data from Location 

Strategy Information Reliability Level 90% 

Geometry 

New Slab Thickness = 250 mm 

New Slab Width = 3.65 m 

Transverse Joint Spacing = 4.5 m 

Dowels Analysis Disabled 

Design 

Slab Support 

Material Type = HMA (rough) 

k-value = 55 MPa/m 

Subbase Thickness = 15 mm 

Subbase Modulus = 3500 MPa 

Axial Restraint = Estimate from Material Type 

Cement ASTM Cement Type Classification = Cement Type I 

Blaine Fineness Index = Estimate from Cement Type 

PCC Mix 

Aggregate Type = Siliceous River Gravel (Baseline 

Strategy) Limestone (Comparison Strategy) 

Admixtures = None 

Fly Ash Class = Class F (CaO <= 7.0% 

Coarse Aggregate = 1100 kg/m3

 

Fine Aggregate = 800 kg/m3

 

Water = 128 kg/m3

 

Cement = 284 kg/m3

 

Fly Ash = 60 kg/m3

 

GGBFS = 0 kg/m3

 

Silica Fume = 0 kg/m3

 

PCC Properties 

28-Day Splitting Tensile Strength = 3.2 MPa 

PCC 28-Day Modulus = 35,000 MPa 

PCC Ultimate Drying Shrinkage = Estimate from Mix 

PCC CTE = Estimate from Aggregate Type 

Materials and Mix 

Design 

Maturity Data Default Strength Gain 

Construction Construction 

Initial PCC Mix Temperature = 32.2 oC 

Initial Support Layer Temperature = 31.7 oC 

Curing Method = Single Coat Curing Liquid Compound 

Age Curing Applied = 0 Hours 

Sawcutting: Saw at Optimum Time 

Skip Sawcutting: Not Used 

Strength for Opening to Traffic = Not Relevant for This 

Analysis 

Environment Environment 

Construction Date: July 18, 2002 (year irrelevant for 

analysis since temperatures are historical averages) 

Construction Time: 11:00 a.m. 

Temperature, Windspeed, Relative Humidity, and Cloud 

Cover = Estimate from Location 
 

133 

To perform this analysis, a new long-term JPCP analysis is selected in the project type selection 

screen (see figure 82). The first step is to select the project location under the geography screen of the 

project information tab (see section 7.1). If not yet chosen, use the following icons in the geography 

toolbar to select Austin, TX, in the U.S. map (see figure 84): 

 pin 

 zoom 

 drag 

Next, select “Estimate monthly data from location” under the monthly weather data screen (see 

figure 85). 

To enter the early-age inputs for the siliceous river gravel strategy, select the strategies tab (see 

figure 86). To rename this strategy “Siliceous River Gravel,” right click on it and select “Rename,” or 

select “Rename” from the strategy option on the HIPERPAV II top menu. Under “Strategy Information,” 

the reliability level is set to 90 percent. In the same way, all other inputs shown in table 1 are entered 

under the design, materials and mix design, construction, and environment input screens. For this 

exercise, data for temperature, windspeed, relative humidity, and cloud cover are set to the default values 

estimated for that location. 

After all the above inputs are entered, the user may perform the analysis by clicking on the 

analysis icon of the strategy toolbar (see section 7.2.1.1) or by selecting “Run Analysis” from the strategy 

option on the HIPERPAV II top menu. The results from this analysis are presented in figure 124. The 

results show a high risk of thermal cracking for the siliceous river gravel strategy. 
 

134 

Figure 124. Analysis results for the siliceous river gravel strategy. 

To proceed with the second strategy (using limestone coarse aggregate), the user may either enter 

the information on a new strategy or create a copy of the siliceous river gravel strategy. The later is 

recommended, since all previously entered data that is identical for the second strategy will be 

automatically copied to the second strategy. To do this, select the siliceous river gravel strategy and click 

on the copy strategy icon. “Copy of Siliceous River Gravel Strategy” appears under the strategy list. 

To rename this strategy “Limestone,” right click on it and select “Rename,” or select “Rename” from the 

strategy option on the HIPERPAV II top menu. 

For the limestone strategy, change the aggregate type to limestone in the aggregate type dropdown menu under the PCC mix input screen (see figure 96). 

After completing the inputs for the limestone strategy, perform the analysis by clicking on the 

analysis icon of the strategy toolbar. The result from this analysis is presented in figure 125. Less 

potential for thermal cracking is observed from the results of the limestone strategy as compared to the 

siliceous river gravel strategy. 
 

135 

Figure 125. Analysis screen for limestone strategy. 

After the two early-age strategies have been analyzed, the long-term analysis is performed using 

the inputs shown in table 2. 

To begin the long-term analysis, select “LT JPCP” under the analysis type drop-down (see figure 

114). Then, under “Strategy Information,” select the siliceous river gravel early-age strategy as the base 

strategy and the limestone early-age strategy as the comparison strategy (see figure 126). Complete the 

rest of the input screens with the information provided in table 2. 
 

136 

Table 2. Long-term inputs for aggregate selection sample scenario. 

Input Category Input Screen Input Value 

Strategy Information Strategy Information Base Strategy: Siliceous River Gravel 

Comparison Strategy: Limestone 

Performance 

Parameters 

Performance 

Parameters 

Analysis Period: 30 Years 

Reliability Level: 90% 

Initial Ride: 0.8 m/km 

Consider Built-in Curling Effect: Yes 

Distress Thresholds: 

Maximum Joint Faulting: 3 mm 

Maximum Transverse Cracking: 25% 

Maximum Longitudinal Cracking: 25% 

Maximum Ride (IRI): 2.7 m/km 

Minimum Serviceability: 2.0 

Joint Design Joint Design 

Load Transfer Devices: Dowels and Tie-bars 

Dowel Properties: 

Size (Diameter): 32 mm 

Spacing: 300 mm 

Modulus: 200,000 MPa 

Tiebar Layout: 

Size: 19.1 mm 

Spacing: 0.9 m 

Transverse Sawcut Depth: 33% of Thickness 

General Mean Truck Tire Pressure: 0.84 MPa 

Traffic Load Spectra: Estimate Spectra from ESAL 

Annual ESAL (Design Lane): 250,000 

Single Axle Load Estimate from ESAL 

Tandem Axle Load Estimate from ESAL 

Tridem Axle Load Estimate from ESAL 

Traffic Loading 

Growth Rate Growth Function: Linear 

Annual Growth Rate: 3% 

Plot Method: Annual 

After all the inputs have been entered, the user may perform the analysis by clicking on the 

analysis icon of the strategy toolbar (see section 7.2.1.1) or by selecting “Run Analysis” from the strategy 

option on the HIPERPAV II top menu. The joint faulting analysis is presented after the analysis is run. 

Transverse cracking may be selected from the distress to plot drop-down menu (see figure 122). The 

transverse cracking results for the siliceous river gravel and limestone early-age strategies are shown in 

figure 127. The strategy with siliceous river gravel coarse aggregate shows a greater development of 

transverse cracking compared to the strategy with limestone coarse aggregate. From this analysis, 

selecting the limestone coarse aggregate source with a lower CTE appears to result in better performance, 

both in the early age and in the long term. 
 

137 

Figure 126. Selection of early-age strategies to compare. 

Figure 127. Long-term strategy transverse cracking results. 
 

138 

7.4 EARLY-AGE CRCP ANALYSIS 

In this section, the analysis for an early-age CRCP project is demonstrated. 

After the user selects option 3 in the project type selection screen (figure 82), the software creates 

an early-age CRCP strategy with default inputs that the user can modify with the inputs for the specific 

situation. The input screens are similar to those required for the early-age JPCP analysis, with some 

differences. 

After the general project information is entered, as shown in section 7.1, one or more strategies 

for that specific location can be created for analysis under the strategies section. 

7.4.1 Early-Age CRCP Strategies Section 

The strategies section contains, in tree view, the specific input data required to perform an earlyage CRCP analysis under the categories of: 

• Design. 

• Materials and mix design. 

• Construction. 

• Environment. 

7.4.1.1 Strategy Toolbar 

For information on the strategy toolbar, see section 7.2.1.1. 

7.4.1.2 CRCP Strategy Information 

Under the strategy information screen, the user can enter his or her name. After the strategy is 

run, the date of analysis also will appear on this screen. A comment box is available for each strategy. 

This screen is similar to the strategy information screen for early-age JPCP analyses, although no 

reliability information is required (see figure 86). 

7.4.2 CRCP Design Inputs 

Under the design inputs, the user can enter the pavement design information, including pavement 

geometry, steel design, and slab support information. 

7.4.2.1 CRCP Geometry 

The geometry screen (figure 128) provides fields to enter the slab thickness and slab width. The 

slab width that should be input in HIPERPAV II is the widest spacing between adjacent longitudinal 

joints. 
 

139 

Figure 128. Geometry screen for early-age CRCP analysis. 

In addition, long-term desirable CRCP cracking characteristics (after 1 year), including minimum 

and maximum crack spacing and average crack width, can be entered; these later will be shown by the 

dashed lines in the early-age CRCP analysis plot. 

7.4.2.2 CRCP Steel Design 

The longitudinal steel information can be input to the program in the steel design screen (figure 

129). Information about the longitudinal steel layout and steel properties is required. For the steel layout, 

the bar spacing and size are needed, as well as the number of steel mats. The steel properties needed are 

the steel yield strength, steel modulus, and CTE. HIPERPAV II then calculates, based on the input, the 

percent steel for the current slab thickness. 
 

140 

Figure 129. Steel design screen for early-age CRCP analysis. 

7.4.2.3 Slab Support 

For information about this screen, see section 7.2.2.3. 

7.4.3 Materials and Mix Design Inputs 

The second input category is materials and mix design (see section 7.2.3).

7.4.4 Construction 

The third input category corresponds to construction information. The construction screen for the 

early-age CRCP analysis is shown in figure 130. In this screen, the initial temperatures of the concrete 

mix and support layer are entered. Information on the curing method used (pulldown) is required along 

with the time of application, and if removable curing methods are selected, the age when curing is 

removed also is required. 

In addition, if the effect of construction traffic is enabled, loading conditions are required. The 

user can assess the influence of construction traffic on the performance of the CRCP by inputting the days 

before the wheel load is applied, the wheel load, and the radius of the circular loaded area. 
 

141 

Figure 130. Early-age construction screen for early-age CRCP analysis. 

7.4.5 Environment 

The environment screen is the same as the early-age JPCP screen seen in section 7.2.5. 

7.4.6 Post 72-Hour Temperatures 

For the early-age CRCP analysis, the post 72-hour temperatures are required (figure 131). The 

user may estimate these inputs using the HIPERPAV II environmental database, or the user can define 

them. The critical analysis period corresponds to the time when construction traffic is applied. For this 

period, the minimum and maximum air temperatures are also required. In addition, after the critical 

analysis period, the date of the minimum temperature for the year is needed to estimate the pavement age 

for the largest temperature drop to which the pavement will be subjected. This date can be estimated by 

HIPERPAV II, or it can be defined by the user. Similarly, HIPERPAV II can either estimate the 

minimum and maximum temperatures, or these can be input. 

Early age in HIPERPAV II includes the first 72 hours after construction for both JPCP and 

CRCP. Cracking in CRCP typically progresses until approximately 1 year after construction. After 1 

year, cracking typically remains constant. The HIPERPAV II analysis extends beyond early age up to 1 

year (early life) to realistically assess the behavior of CRC pavements inservice. 
 

142 

Figure 131. Post 72-hour air temperatures screen for early-age CRCP analysis. 

7.4.7 CRCP Analysis 

With the input assigned, the user should save the file before performing an early-age CRCP 

analysis. The analysis screen for an early-age CRCP strategy is shown in figure 132. After the analysis is 

run, a window appears showing the analysis status. The analysis output, in tabular format, includes the 

average crack spacing and its standard deviation, the average crack width, the maximum steel stress, and 

the bond development length. Interpretation of the analysis is performed by comparing the cracking 

results with the thresholds previously set in “Desirable CRCP Cracking Characteristics” in the geometry 

input screen. These thresholds are also presented in the analysis screen for comparison. 

The plot can either show the incremental or cumulative frequency versus crack spacing. Plots for 

three different points in time are provided: 1) at 3 days after construction; 2) for the critical analysis 

period when construction traffic is applied; and 3) at 1 year of age (“Time Period to Plot” pulldown in 

figure 133). The crack spacing frequency also is presented in tabular format. The numerical value of 

crack spacing frequency can also be obtained by hovering the mouse over the point of interest in the plot. 

As shown in figure 134, a help window is provided to caution the user on the validation of the crack 

width model incorporated in HIPERPAV II. This window also defines the analysis period used for CRCP 

behavior analyses. 

Also, because more than one strategy can be analyzed with HIPERPAV II, comparisons can be 

made between the analysis results more easily. It is possible to toggle between the analysis screens by 

selecting one strategy and then the other one (for this, the user must have analyzed at least two strategies 

previously for comparison and toggled between them). 

An analysis screen also is provided for evaporation rate. The evaporation rate analysis is the same 

as for the early-age JPCP (see section 7.2.6.2). 
 

143 

Figure 132. Analysis screen for early-age CRCP. 

Figure 133. Drop-down menu for time period to plot. 
 

144 

Figure 134. Help icon under CRCP analysis screen. 

7.4.8 Interpretation of CRCP Analysis 

One of the objectives of the CRCP analysis is to achieve a crack spacing distribution that falls 

within the predefined thresholds, with only a small percentage of cracks falling above and/or below the 

maximum and minimum crack spacing limits, respectively, as shown in figure 132. In this analysis, both 

crack width and crack spacing are within acceptable limits. An example of a CRCP analysis with poor 

cracking characteristics is shown in figure 135. In this second analysis, neither crack spacing nor crack 

width fall within acceptable limits. In addition, a large percentage of crack spacings fall below the 

predefined minimum crack spacing threshold. 
 

145 

Figure 135. CRCP analysis with poor cracking characteristics. 

It is also recommended to compare the maximum steel stress predicted with the steel yield 

strength to evaluate the potential of wide cracks or steel rupture. The bond development length is 

predicted to compare with the predicted crack spacing. The user should achieve a minimum average 

crack spacing of twice the bond development length to ensure good CRCP behavior. For additional 

information on CRCP behavior, refer to section 2.3. 

7.5 HIPERPAV II Reports 

For any HIPERPAV II analysis, reports can be generated by clicking on the print icon on the 

upper icon toolbar or by selecting “Print” from the file menu. After selecting “Print,” a HIPERPAV II 

report screen is displayed as shown in figure 136. In this screen, options are available to select printing 

options under the setup icon, send the report to the printer as-is under the print icon, preview the report 

under the preview icon, and export the results to a Microsoft Excel spreadsheet under the export icon. 
 

146 

Figure 136. HIPERPAV II report screen. 

7.6 COMET Module 

The Concrete Optimization, Management, Engineering, and Testing (COMET) module is a 

simplified derivation of the Concrete Optimization Software Tool (COST) that was developed by FHWA 

and the National Institute of Standards and Technology (NIST) for optimizing concrete mixes. COMET 

can be accessed within HIPERPAV II by selecting “COMET” in the tools top menu bar shown in figure 

137. COMET optimizes concrete mixes based on early-age strength, 28-day strength, and cost. 

Figure 137. Tools drop-down menu in HIPERPAV II. 

Once selected, the COMET initial window appears as shown in figure 138. Inputs and outputs 

can be selected on the tree view on the left side of the screen. The inputs for the screen selected are 

displayed on the right. The first item on the tree view, “Event Log,” reports potential problems that may 

arise while running the software. Also, the tree view shows two levels of inputs and outputs. Level 1 

inputs generate the experiment design of trial batches required for optimization. Level 2 inputs produce a 

set of optimum mixes based on the trial batch test results, and desirability functions defined for each 

response (early-age strength, 28-day strength, and cost). 
 

147 

As shown in figure 138, mix constituents are limited to cement, pozzolan, water, coarse 

aggregate, and fine aggregate. For each constituent, the specific gravity and cost is required. 

Figure 138. Mix constituents input screen in COMET. 

The user provides optimization ranges for coarse aggregate fraction, cementitious content, 

pozzolan substitution, and w/cm ratio (see figure 139). 
 

148 

Figure 139. Factor limits input screen in COMET. 

With the inputs in level 1, trial batches are developed for the experimental program by running 

the “Create Trial Batches” command button in the level 1 outputs screen, as shown in figure 140. As a 

result, 29 trial batches are generated, which can be displayed in volumetric (percent of total volume) and 

gravimetric (weight per unit of volume) form. The gravimetric form is presented in figure 141. 

Figure 140. Create trial batches command button in level 1 outputs. 
 

149 

Figure 141. Trial batches in kg/m3

, gravimetric form. 

In addition, as shown in figure 142, the cost for every trial batch is computed and default models 

in COMET are used to predict early-age strength and 28-day strength as a function of mix constituents. 

Predicted responses are only approximate and may be used in a planning stage in which the mix 

constituents may not be known or are not available for testing. 
 

150 

Figure 142. Predicted responses for each trial batch. 

After the level 1 inputs and outputs are complete, the user can proceed with level 2 analysis. To 

continue with this analysis, the user must enter the laboratory testing results for each response for the trial 

batches generated in level 1 (see figure 143). Alternatively, the user may fill in these values using default 

models by clicking on the “Reset to Predicted Values” command button, if a preliminary analysis is 

desirable. 
 

151 

Figure 143. Lab results screen. 

The user can assign desirability functions for each of the optimization responses under the cost, 

early-age strength, and 28-day strength desirability screens (a sample desirability function is shown in 

figure 144 for 28-day strength). 

Figure 144. Desirability function for 28-day strength. 
 

152 

After the level 2 inputs are entered, optimization of mixes is performed by clicking the “Optimize 

Mixes” command button in the level 2 outputs screen (see figure 145). With this command, regression 

models based on the results from the experimental program or from the predicted responses are developed 

as a function of the mix proportions. 

Figure 145. Level 2 outputs—command to optimize mixes. 

These models predict responses for a comprehensive set of mixtures within the factor limits 

specified in the factor limits screen. Finally, optimum mixes are identified in terms of the individual 

desirability for every response and the maximum overall desirability for all responses, and are presented 

in volumetric and gravimetric form. Optimum mixes are shown in volumetric form in figure 146. 
 

153 

Figure 146. Optimum mixes sorted by desirability in volumetric form. 

In addition, the optimum mixes are also displayed in terms of the optimization factors, predicted 

responses, and individual response desirabilities as shown in figures 147, 148, and 149, respectively.
154 

Figure 147. Optimum mixtures in terms of optimization factors. 
 

155 

Figure 148. Response predictions for optimum mixtures. 

Figure 149. Individual response desirabilities for optimum mixtures. 
 

156 

A report that can be used for printing the inputs and outputs for the entire analysis is generated, as 

shown in figure 150. To print, click on the print icon on the upper icon toolbar. 

Figure 150. Report view for printing purposes. 
 

157 

REFERENCES 

1. McCullough, B.F. and Rasmussen, R., Fast-Track Paving: Concrete Temperature Control and 

Traffic Opening Criteria for Bonded Concrete Overlays, Volume I: Final Report, FHWA–RD–98–

167, Federal Highway Administration, Washington, DC, 191 pp., October 1999. 

2. McCullough, B.F., Abou-Ayyash, A., Hudson, W.R. and Randall J.P., Design of Continuously 

Reinforced Concrete Pavements for Highways, Research Project NCHRP 1–15, Center for Highway 

Research, The University of Texas at Austin, Austin, TX, August 1975. 

3. Suh, Y.C., Hankins K., and McCullough, B.F., Early-Age Behavior of Continuously Reinforced 

Concrete Pavement and Calibration of the Failure Prediction Model in the CRCP–7 Program, 

Research Report 1244–3, Center for Transportation Research, The University of Texas at Austin, 

Austin, TX, March 1992. 

4. Maekawa, K., Chaube, R., and Kishi, T., Modeling of Concrete Performance, Hydration, 

Microstructure Formation, and Mass Transport, E & FN Spon, London and New York, NY, 1999. 

5. Burrows, R.W., “The Visible and Invisible Cracking of Concrete,” Monograph No. 11, American 

Concrete Institute, 1998. 

6. Kosmatka, S.H. and Panarese, W.C., Design and Control of Concrete Mixtures, Thirteenth Edition, 

Portland Cement Association, Skokie, IL, 1990. 

7. Aïtcin, P.C., Neville, A.M., and Acker, P., “Integrated View of Shrinkage Deformation,” Vol. 19, No. 

9, Concrete International, September 1997, pp. 35–41. 

8. Aïtcin, P.C., “Demystifying Autogenous Shrinkage,” Vol. 21, No. 11, Concrete International, 

November 1999, pp. 54–56. 

9. Neville, A., Properties of Concrete, Fourth Edition, John Wiley & Sons Inc., New York, NY, 535 

pp., 1999. 

10. Byfors, J., Plain Concrete at Early Ages, Research 3:80, Swedish Cement and Concrete Research 

Institute, Cement och Betong Institutet (CBI), Stockholm, Sweden, 1980. 

11. Emborg, M., “Thermal Stress in Concrete Structures at Early Ages,” Doctoral Thesis, Luleå 

University of Technology, Division of Structural Engineering, 285 pp., 1989. 

12. Poblete, M., Valenzuela, R., and Salsilli R., Load Transfer in Undoweled Transverse Joints of PCC 

Pavements, Transportation Research Record 1207, Washington DC, 1988. 

13. Nowlen, W.J., Influence of Aggregate Properties on Effectiveness of Interlock Joints in Concrete 

Pavements, Bulletin D139, Vol. 10, No. 2, Portland Cement Association, 1968. 

14. Hansen, W., Jensen, E., Mohr, P., Jensen, K., Pane, I., and Mohamed, A., The Effects of Higher 

Strength and Associated Concrete Properties on Pavement Performance, FHWA–RD–00–161, June 

2001. 

15. Huang, Y.H., Pavement Analysis and Design, Prentice Hall, Englewood Cliffs, NJ, 1993. 
 

158 

16. McCullough, B.F., Dossey, T., and Zollinger, D., Evaluation of the Performance of Texas Pavements 

Made with Different Coarse Aggregates, Texas Department of Transportation, Report No. TX–01/7–

3925–1, October 2000. 

17. AASHTO Guide for Design of Pavement Structures 1993, American Association of State Highway 

and Transportation Officials, Washington, DC, 1993. 

18. Zollinger, D.G., Buch, N., Xin, D., and Soares, J., Performance of CRC Pavements Volume 6—CRC 

Pavement Design, Construction and Performance, FHWA–RD–97–151, Federal Highway 

Administration, Washington, DC, 1997. 

19. Otero, M.A., McCullough, B.F., and Hankins, K., Monitoring of Siliceous River Gravel and 

Limestone Continuously Reinforced Concrete Pavement Test Sections in Houston 2 Years After 

Placement, and Development of a Crack Width Model for the CRCP–7 Program, Research Report 

1244–4, Center for Transportation Research, The University of Texas at Austin, Austin, TX, March 

1992. 

20. McCullough, B.F., Ma, J.C.M., and Noble, C.S., Limiting Criteria for the Design of CRCP, Research 

Report 177–17, Center for Transportation Research, The University of Texas at Austin, Austin, TX, 

August 1979. 

21. Elfino, M., Ozyildirim, C., and Steele, R., “CRCP in Virginia, Lessons Learned,” CD Proceedings of 

the 7th International Conference on Concrete Pavements, Orlando, FL, September 9–13, 2001. 

22. Yu, H.T., Khazanovich, L., Darter, M., and Ardani, A., “Analysis of Concrete Pavement Responses to 

Temperature and Wheel Loads Measured from Instrumented Slabs,” Transportation Research Board, 

77th Annual Meeting, Washington, DC, January 11–15, 1998. 

23. Uno, P.J., “Plastic Shrinkage Cracking and Evaporation Formulas,” ACI Materials Journal, American 

Concrete Institute, Vol. 95, No. 4, July–August 1998. 

24. Poole, T.S., Curing of Portland Cement Concrete Pavements, Interim Report, Report prepared for 

FHWA by U.S. Army Corps of Engineers Research and Development Center, February 7, 2000. 

25. Practitioner’s Guide to Hot Weather Concreting, American Concrete Institute, PP-2, 1998. 

26. Smith, K.D., Wade, M.J., Peshkin, D.G., Khazanovich, L., Yu, H.T., and Darter M.I., Performance 

of Concrete Pavements, Volume II: Evaluation of Inservice Concrete Pavements, FHWA–RD–95–

110, Federal Highway Administration, Washington, DC, June 1998. 

27. Hansen, E.C., Johannesen, R., and Armaghani, J.M., “Field Effects of Water Pumping Beneath 

Concrete Pavement Slabs,” Journal of Transportation Engineering, Vol. 117, No. 6, November–

December 1991. 

28. Richter, C., “LTPP Data Analysis: Frequently Asked Questions about Joint Faulting with Answers 

from LTPP,” TechBrief, FHWA–RD–97–101, Federal Highway Administration, Washington, DC, 

1997. 

29. VanWijk, A.J. and Lovell, C.W., “Prediction of Subbase Erosion Caused by Pavement Pumping,” 

Transportation Research Record 1099, pp. 45–57, 1987. 
 

159 

30. Simpson, A.L., Rauhut, J.B., Jordahl, P.R., Owusu-Antwi, E., Darter, M.I., Ahmad, R., Pendleton, 

O.J., and Lee, Y.-H., Sensitivity Analyses for Selected Pavement Distresses, Strategic Highway 

Research Program, SHRP–P–393, Washington, DC, 1994. 

31. Bendana, L.J. and Yang, W.-S., “Rehabilitation Procedures for Faulted Pavement,” Transportation 

Research Record 1388, pp. 200–210, 1993. 

32. Bustos, M., de-Solminhac, H.E., Darter, M.I., Caroca, A., and Covarrubias, J.P., “Calibration of 

Performance Models for Jointed Concrete Pavements Using Long-Term Pavement Database,” 

Transportation Research Record 1629, pp. 108–116, 1998. 

33. Titus-Glover, L., Owusu-Antwi, E.B., Hoener, T., and Darter, M.I., Design and Construction of PCC 

Pavements, Volume II: Design Features and Practices that Influence Performance of Pavements, 

FHWA–RD–98–127, Federal Highway Administration, Washington, DC, October 1998. 

34. Ioannides, A.M., Lee, Y., and Darter, M.I., “Control of Faulting through Joint Load Transfer 

Design,” Transportation Research Record 1286, National Research Council, Washington DC, pp. 49–

56, 1990. 

35. Titus-Glover, L., Owusu-Antwi, E.B., and Darter, M.I., Design and Construction of PCC Pavements. 

Volume III: Improved PCC Performance Models, FHWA–RD–98–113, Federal Highway 

Administration, Washington, DC, January 1999. 

36. Sargaand, S.M., Performance of Dowel Bars and Rigid Pavement, Ohio Department of 

Transportation, FHWA/HWY–01/2001, June 2001. 

37. Smith, K.D., Mueller, A.L., Darter, M.I., and Peshkin, D.G., Performance of Jointed Concrete 

Pavements. Volume II—Evaluation and Modification of Concrete Pavement Design and Analysis 

Models, FHWA–RD–89–137, Federal Highway Administration, Washington, DC, July 1990. 

38. Smith, K.D., Peshkin, D.G., Darter, M.I., Mueller, A.L., and Carpenter, S.H., Performance of Jointed 

Concrete Pavements. Volume V—Appendix B Data Collection and Analysis Procedures, FHWA–

RD–89–140, Federal Highway Administration, Washington, DC, March 1990. 

39. Yu, H.T., Smith, K.D., Darter, M.I., Jiang, J., and Khazanovich, L., Performance of Concrete 

Pavements Volume III—Improving Concrete Pavement Performance, FHWA–RD–95–111, Federal 

Highway Administration, McLean, VA, 1995. 

40. Moody, E.D., “Transverse Cracking Distress in Long-Term Pavement Performance of Jointed 

Concrete Pavement Sections,” Transportation Research Record 1629, Texas Transportation Institute, 

Texas A&M University, College Station, TX, pp. 6–12, 1998. 

41. Ramsamooj, D.V., “Stresses in Jointed Rigid Pavements,” Journal of Transportation Engineering, 

pp. 101–108, March–April 1999. 

42. Rollings, R.S., “Joint Spalling in Newly Constructed Concrete Pavements,” Journal of Performance 

of Constructed Facilities, pp. 137–144, August 1998. 

43. Senadheera, S.P. and Zollinger, D.G., Influence of Coarse Aggregate in Portland Cement Concrete 

on Spalling of Concrete Pavements, Research Report 1244–11, Texas Transportation Institute, The 

Texas A&M University System, College Station, TX, 1994. 
 

160 

44. Zollinger, D.G. and Senadheera, S.P., “Spalling of Continuously Reinforced Concrete Pavements,” 

Journal of Transportation Engineering, Vol. 120, No. 3, May–June 1994. 

45. Merritt, D.K., McCullough, B.F., and Burns, N.H., “Texas Tests Precast for Speed and Usability,” 

Public Roads, Vol. 66, No. 1, Federal Highway Administration, Washington, DC, July–August 2002. 

46. Won, M., Hankins, K., and McCullough, B.F., Mechanistic Analysis of Continuously Reinforced 

Concrete Pavements Considering Material Characteristics, Variability and Fatigue, Research Report 

1169–2, Center for Transportation Research, The University of Texas at Austin, Austin, TX, March 

1991. 

47. Colley, B.E. and Humphrey, H.A., “Aggregate Interlock at Joints in Concrete Pavements,” 

Proceedings of the Highway Research Board 46th Annual Meeting, Report HRR 189, pp. 1–18, 

Washington, DC, 1967. 

48. Bayasi, Z., Effects of Fly Ash on the Properties of Silica-Fume Concrete, Mineral Admixtures, 

American Concrete Institute, Compilation 22, 1993. 

49. Nawy, E.G., Concrete Construction Engineering Handbook, CRC Press, Boca Raton, FL, 1997. 

50. ASTM C 1074–98 Standard Practice for Estimating Concrete Strength by the Maturity Method, 

American Society for Testing and Materials, 1998. 

51. Yoder, E.J. and Witczak, M.W., Principles of Pavement Design, John Wiley & Sons, Inc., 1975. 

52. Packard, R.G., Design of Concrete Airport Pavement, Engineering Bulletin 050.03P, Portland 

Cement Association, 1973. 

53. Okamoto, P.A, Naussbaum, P.J., Smith, K.D., Darter, M.I., Wilson, T.P., Wu, C.L., and Tayabji, 

S.D., Guidelines for Timing Contraction Joint Sawing and Earliest Loading for Concrete Pavements, 

Volume 1: Final Report, FHWA–RD–91–079, Federal Highway Administration, Washington, DC, 

February 1994. 

54. Ioannides, A.M. and Korovesis, G.T., “Analysis and Design of Doweled Slab-on-Grade Pavement 

Systems,” Journal of Transportation Engineering, Vol. 118, No. 6, pp. 745–768, November–

December 1992. 

55. Robert, O.R. and Rozycki, D.K., “Characterization and Modeling of Axial Slab-Support Restraint,” 

Transportation Research Record No. 1778, Transportation Research Board, National Research 

Council, Washington, DC, 2001. 
FHWA-HRT-04-122 COMPUTER-BASED GUIDELINES FOR CONCRETE PAVEMENTS, 

VOLUME II: DESIGN AND CONSTRUCTION GUIDELINES AND HIPERPAV

® II USER’S MANUAL
HRDI-11/02-05(1M)E Recycled

Recyclable