Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

Design and Evaluation of Jointed 

Plain Concrete Pavement with 

Fiber Reinforced Polymer Dowels

Publication No. FHWA-HRT-06-106 SEPTEMBER 2009
FOREWORD 

This study evaluates fiber reinforced polymer (FRP) dowel bars as load transferring devices in 

jointed plain concrete pavement (JPCP) under HS25 static and fatigue loads and compares their 

response with JPCP consisting of steel dowels. Along with laboratory and field evaluations of 

JPCP with FRP and steel dowels, analytical modeling of dowel response has been carried out in 

terms of maximum bending deflection, relative deflection, and bearing stress of dowels. 

Response of concrete pavement with FRP dowels is investigated through laboratory experiments 

and field implementation. This research showed that JPCP with FRP dowels provided very good 

load transfer efficiency (LTE). JPCP with FRP dowels provided sufficient LTE after 5 million 

cycles of fatigue tests under HS25 loading conducted in the Major Units Laboratory of West 

Virginia University. 

Cheryl Allen Richter 

Acting 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.
TECHNICAL DOCUMENTATION PAGE 

1. Report No. 

FHWA-HRT-06-106 

2. Government Accession No. 3. Recipient’s Catalog No. 

4. Title and Subtitle 

Design and Evaluation of Jointed Plain Concrete Pavement 

with Fiber Reinforced Polymer Dowels 

5. Report Date 

September 2009 

6. Performing Organization Code: 

7. Author(s) 

Vijay, P.V., Hota V.S. GangaRao, and Li, H.

8. Performing Organization Report No. 

9. Performing Organization Name and Address 

Constructed Facilities Center 

Department of Civil and Environmental Engineering 

West Virginia University 

Morgantown, WV 26506 

10. Work Unit No. 

11. Contract or Grant No. 

DTFH61-99-X-00078

12. Sponsoring Agency Name and Address 

Office of Research and Technology Services 

Federal Highway Administration 

6300 Georgetown Pike 

McLean, VA 22101-2296 

13. Type of Report and Period Covered 

Final Report, November 1999 to July 2003 

14. Sponsoring Agency Code 

Insert FHWA sponsoring agency office code (i.e., 

HRTS-01) 

15. Supplementary Notes 

FHWA Contracting Officer’s Technical Representative (COTR): Peter Kopac, Pavement Materials and 

Construction Team 

16. Abstract 

This study evaluates fiber reinforced polymer (FRP) dowel bars as load transferring devices in jointed plain 

concrete pavement (JPCP) under HS25 static and fatigue loads and compares their response with JPCP consisting 

of steel dowels. Along with laboratory and field evaluations of JPCP with FRP and steel dowels, analytical 

modeling of dowel response was carried out in terms of maximum bending deflection, relative deflection (RD), 

and bearing stress of dowels. In addition, field rehabilitation of JPCP was carried out using FRP dowels to 

evaluate its long-term performance. Laboratory tests included static and fatigue load application corresponding to 

HS25 load and 1.5 times HS25 load on concrete slabs (27.94- and 30.48-cm (11- and 12-inch) depth) with 3.81- 

and 2.54-cm (1.5- and 1.0-inch) steel and FRP dowels at different spacings (30.48 and 15.24 cm (12 and 

6 inches)). Both 3.81- and 2.54-cm (1.5- and 1.0-inch)-diameter FRP dowels were installed in the field with 

15.24-, 20.32-, 22.86-, and 30.48-cm (6-, 8-, 9-, and 12-inch) spacings. Load calibrated field tests were conducted 

on these pavements using a West Virginia Department of Transportation truck in 2002 and 2003. FRP dowel bars 

that were 1.5 inches in diameter were also used for pavement rehabilitation. Field data collected through an 

automatic data acquisition system included strain and joint deflections, which were used for assessing joint load 

transfer efficiency (LTE), joint RD, and pavement performance. Theoretical calculations are provided through 

different examples for JPCP with FRP and steel dowels by varying dowel diameters, spacing, dowel material 

properties, joint width, and base material properties. This research showed that JPCP with FRP dowels provided 

very good LTE up to and beyond 90 percent, which exceeds the American Association of State Highway and 

Transportation Officials and American Concrete Pavement Association criteria. JPCP with FRP dowels also 

provided sufficient LTE after 5 million cycles of fatigue tests under HS25 loading. 

17. Key Words 

GFRP, Glass fiber reinforced polymer, FRP 

dowel, JPCP, Jointed plain concrete pavement, 

Relative deflection, Joint efficiency, Dowel 

18. Distribution Statement 

No restrictions. This document is available through the 

National Technical Information Service, Springfield, VA 

22161. 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 

160 

22. Price 

N/A 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
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. Approp e riate rounding should be made to comply with Section 4 of ASTM E380. 

(Revised March 2003)
iii 

TABLE OF CONTENTS 

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

GENERAL REMARKS ......................................................................................................... 1

OBJECTIVES ......................................................................................................................... 2

SCOPE ..................................................................................................................................... 2

CHAPTER 2. LITERATURE REVIEW .................................................................................... 5

INTRODUCTION................................................................................................................... 5

LITERATURE REVIEW FINDINGS .................................................................................. 5

CHAPTER 3. MATERIALS, EQUIPMENT, AND LABORATORY TESTING 

PROCEDURES ............................................................................................................................. 7

INTRODUCTION................................................................................................................... 7

MATERIAL PROPERTIES .................................................................................................. 7

GFRP Dowels ..................................................................................................................... 7

Steel Dowels ....................................................................................................................... 9

Concrete .............................................................................................................................. 9

Base ..................................................................................................................................... 9

FORMWORK ......................................................................................................................... 9

TEST SETUP .......................................................................................................................... 9

Specimen Fabrication.......................................................................................................... 9

Material Preparations ................................................................................................ 11

Pavement Slab Casting ............................................................................................... 11

Test Specimens ............................................................................................................ 14

Test Setup and Instrumentation ........................................................................................ 16

Static Testing ............................................................................................................... 17

Fatigue Testing ........................................................................................................... 18

CHAPTER 4. EXPERIMENTAL RESULTS AND DISCUSSION ....................................... 19

INTRODUCTION................................................................................................................. 19

JOINT CRACK PATTERNS OBSERVED IN LABORATORY TESTS ....................... 19

PRELIMINARY TESTS ...................................................................................................... 22

JOINT DEFLECTIONS AND JOINT LTE ....................................................................... 22

Joint RD ............................................................................................................................ 22

Joint RD of Group 1 .................................................................................................... 22

Joint RD of Group 2 .................................................................................................... 28

Analysis of RD............................................................................................................. 30

Joint LTE .......................................................................................................................... 32

LTE of Group 1 ........................................................................................................... 33

Joint LTE of Group 2 .................................................................................................. 37

Analysis and Discussion for Joint LTE ....................................................................... 40

Investigations on Pavement Pumping Problem ................................................................ 42

Strains on Dowels ............................................................................................................. 47

CHAPTER 5. FIELD APPLICATIONS AND TEST RESULTS .......................................... 49

INTRODUCTION................................................................................................................. 49

FRP DOWELS FOR NEW HIGHWAY PAVEMENT CONSTRUCTION ................... 49
iv 

Field Locations.................................................................................................................. 49

Field Installation ............................................................................................................... 51

FIELD TESTS ....................................................................................................................... 54

Field Test Before Opening Highway to Traffic in July 2002 ........................................... 54

Test Setup .................................................................................................................... 55

Test Results and Analysis ............................................................................................ 57

Field Test after Highway Opened to Traffic, June 2003 .................................................. 64

Test Results from Field Test ........................................................................................ 67

Summary and Analysis of Test Results........................................................................ 70

FRP DOWELS USED FOR HIGHWAY PAVEMENT REHABILITATION ............... 74

Field Location ................................................................................................................... 74

Field Installation ............................................................................................................... 75

FIELD TESTS ....................................................................................................................... 77

Test Setup.......................................................................................................................... 77

Results and Analysis ......................................................................................................... 78

FRP Dowel Group ...................................................................................................... 78

Steel Dowel Group ...................................................................................................... 79

CONCLUSION ..................................................................................................................... 80

Effect of Dowel Spacing ................................................................................................... 80

Effect of Dowel Diameter ................................................................................................. 81

CHAPTER 6. ANALYTICAL EVALUATION ....................................................................... 83

INTRODUCTION................................................................................................................. 83

ANALYTICAL MODEL...................................................................................................... 83

Load Transfer Across a Joint ............................................................................................ 86

Dowel Bending Moment and Shear .................................................................................. 89

Dowel Bar Deflection and Bearing Stress ........................................................................ 89

Bearing Stress Between Dowel/Concrete Interfaces ........................................................ 90

Pavement Joint Efficiency ................................................................................................ 91

THEORETICAL CALCULATION SAMPLES FOR FRP AND STEEL DOWEL 

GROUP .................................................................................................................................. 92

Theoretical Calculation for Dowel Group with 3.81-cm (1.5-inch)-Diameter Dowels .... 92

Example 1.................................................................................................................... 92

Discussion for Contraction Joint Model ........................................................................... 97

Example 2.................................................................................................................... 98

Theoretical Calculation for Dowel Group with 2.54-cm (1.0-inch)-Diameter Dowels .... 101

Example 3.................................................................................................................. 101

Discussion for Contraction Joint Model ......................................................................... 105

Example 4.................................................................................................................. 106

DISCUSSIONS ON 3.81-CM (1.5-INCH) AND 2.54-CM (1.0-INCH)-DIAMETER 

DOWELS ............................................................................................................................. 108

Comparisons for 2.54-cm (1.5-inch)-Diameter Dowel Bars .......................................... 108

Effect of Dowel Material ........................................................................................... 110

Effect of Dowel Spacing ............................................................................................ 111

Effect of Joint Width .................................................................................................. 111

Effect of Dowel Length .............................................................................................. 112

Effect on Bearing Stress ............................................................................................ 112
v 

Comparisons for 2.54-cm (1.0-inch)-Diameter Dowel Bars .......................................... 112 

Effect of Dowel Material ........................................................................................... 115

Effect of Dowel Spacing ............................................................................................ 115

Effect of Joint Width .................................................................................................. 115

Effect of Dowel Length .............................................................................................. 116

Effect on Bearing Stress ............................................................................................ 116

COMPARISON OF EXPERIMENTAL VERSUS THEORETICAL DATA ............... 116

ANALYTICAL INVESTIGATION WITH RESPECT TO FRP DOWELCONCRETE BEARING STRESS .................................................................................... 117

CHAPTER 7. CONCLUSIONS AND RECOMMENDATIONS ......................................... 121

INTRODUCTION............................................................................................................... 121

CONCLUSIONS FOR LABORATORY TESTS ............................................................. 121

Joint RD .......................................................................................................................... 122

For Specimens (Numbers 1, 4, and 5) Having Proper Crack Formation at Joint 

Locations (Table 6) ................................................................................................... 122

For Specimens Having Crack Formation away from Joint Location (Table 7) ....... 122

For Base Material Properties (Table 6) ................................................................... 122

Joint LTE ........................................................................................................................ 122

For Specimens (Numbers 1, 4, and 5) Having Proper Crack Formation at Joint 

Location .................................................................................................................... 123

For Specimens Having Crack Formation away from Joint Location (Table 7) ....... 123

Investigation of Pavement Pumping Problem................................................................. 124

Strains on Dowels ........................................................................................................... 124

CONCLUSIONS FOR FIELD APPLICATIONS AND TEST RESULTS ................... 124

Conclusions for FRP Dowels Used for New Highway Pavement Construction ............ 124

Effect of Dowel Spacing ............................................................................................ 124

Effect of Dowel Diameter .......................................................................................... 125

Relative Deflection .................................................................................................... 125

Conclusions for FRP Dowels Used for Highway Pavement Rehabilitation ................... 126

CONCLUSIONS FOR ANALYTICAL EVALUATION ................................................ 126

Conclusions for 3.81-cm (1.5-inch)-Diameter Dowels with 30.48-cm (12-inch)-c/c 

Spacing ............................................................................................................................ 126

Effect of Dowel Material ........................................................................................... 126

Effect of Dowel Spacing ............................................................................................ 126

Effect of Joint Width .................................................................................................. 127

Effect of Dowel Length .............................................................................................. 127

Effect on Bearing Stress ............................................................................................ 128

Conclusions for 2.54-cm (1.0-inch)-Diameter Dowels with 15.24-cm (6-inch)-c/c 

Spacing ............................................................................................................................ 128

Effect of Dowel Material ........................................................................................... 128

Effect of Dowel Spacing ............................................................................................ 128

Effect of Joint Width .................................................................................................. 129

Effect of Dowel Length .............................................................................................. 129

Effect on Bearing Stress ............................................................................................ 129

GENERAL CONCLUSIONS FROM THIS RESEARCH ............................................. 129

RECOMMENDATIONS .................................................................................................... 131
vi 

APPENDIX A. TEST OF TIMBER TIE WITH FRP DOWELS ........................................ 133

APPENDIX B. ANALYTICAL EVALUATION OF EFFECT OF FRP DOWEL 

SHEAR MODULUS ON PAVEMENT RD ............................................................................ 141

APPENDIX C. FIBER BURNOUT TESTS FOR DETERMINING FIBER WEIGHT 

FRACTION AND FIBER VOLUME FRACTION FOR FRP DOWELS .......................... 145

REFERENCES .......................................................................................................................... 147
vii 

LIST OF FIGURES 

Figure 1. Photo. Exposed failures with rusted dowel bars (Washington State Department of 

Transportation Pavement Guide) .................................................................................................... 2

Figure 2. Typical pavement problems—faulting and pumping ...................................................... 5

Figure 3. Photo. FRP dowels (2.54 and 3.81 cm (1.0 and 1.5 inches) in diameter) ....................... 8

Figure 4. Photo. Steel dowels 3.81 and 2.54 cm (1.5 and 1.0 inches) in diameter ......................... 9

Figure 5. Photo. Wood formwork ................................................................................................. 10

Figure 6. Diagram. Dimensions of formwork ............................................................................... 10

Figure 7. Diagram. Trimmed dowel bar ....................................................................................... 11

Figure 8. Photo. Instrumented dowels and steel plate positioned in the wood formwork ............ 12

Figure 9. Photo. Placing concrete into the formwork ................................................................... 12

Figure 10. Photo. Dowel being covered by concrete .................................................................... 13

Figure 11. Photo. Casting concrete cylinders ............................................................................... 13

Figure 12. Photo. Surface finished specimens .............................................................................. 14

Figure 13. Diagram. Concrete slabs for preliminary tests ............................................................ 14

Figure 14. Diagram. Concrete slabs containing two dowels ........................................................ 15

Figure 15. Diagram. Concrete slabs containing only one dowel .................................................. 16

Figure 16. Photo. Experimental setup ........................................................................................... 17

Figure 17. Photo. LVDTs positioned on both sides of the joint ................................................... 17

Figure 18. Photo. Typical crack observed in slabs number 1, 4, and 5 (table 7) .......................... 20

Figure 19. Photo. Crack observed in slab number 2 (table 7) ....................................................... 20

Figure 20. Photo. Typical crack observed in slab number 3 (table 7) .......................................... 21

Figure 21. Chart. Joint RD for slab number 1 under static test .................................................... 23

Figure 22. Graph. RDs under HS25 loading for slab number 1 at joint width of 0.635 mm 

(0.25 inch) (static and 1 million cycles) ........................................................................................ 23

Figure 23. Graph. RDs for slab number 1 under fatigue tests (joint width increased from 

0.635 cm (0.25 inch) to 1.016 mm (0.4 inch) from 2 to 5 million cycles) ................................... 24

Figure 24. Chart. Joint RD for slab number 2 under static test .................................................... 25

Figure 25. Graph. RDs for specimen 2 (0 to 2 million cycles) ..................................................... 26

Figure 26. Chart. Joint RD for specimen 3 under static test ......................................................... 27

Figure 27. Graph. RDs for specimen 3 (0 to 1.25 million cycles) ................................................ 27

Figure 28. Chart. Joint RD for specimen 4 under static test ......................................................... 28

Figure 29. Graph. Pavement deflections under fatigue test for slab number 4 (0 to 5 million 

cycles, FRP dowel at 30.48 cm (12 inches) c/c) ........................................................................... 29

Figure 30. Graph. RDs under fatigue test for specimen 4 (0 to 5 million cycles) ........................ 29

Figure 31. Chart. Joint RD for specimen 5 under static test ......................................................... 30

Figure 32. Graph. RDs under fatigue test for specimen 5 (0 to 5 million cycles) ........................ 30

Figure 33. Chart. Joint LTE for slab number 1 ............................................................................. 33

Figure 34. Graph. LTE corresponding to HS25 loading for slab number 1 (2.54-cm 

(1.0-inch) diameter at 15.24 cm (6 inches) c/c), static and 1 million cycles ................................ 34

Figure 35. Graph. LTE for slab number 1 under fatigue tests ( > 1 million cycles and joint 

width increased from 0.635 to 1.016 cm (0.25 to 0.4 inch)) ......................................................... 34

Figure 36. Photo. Dowel-concrete interface condition in slab number 1 after 5 million 

load cycles ..................................................................................................................................... 35

Figure 37. Chart. Joint LTE for slab number 2 ............................................................................. 35
viii 

Figure 38. Graph. LTE under fatigue tests (HS25 loading) for slab number 2 (0 to 1 million 

cycles) ........................................................................................................................................... 36

Figure 39. Graph. LTE under fatigue test for slab number 2 (1 to 2 million cycles) ................... 36

Figure 40. Chart. Joint LTE for slab number 3 ............................................................................. 37

Figure 41. Graph. LTE under fatigue test for slab number 3 (0 to 1.25 million cycles) .............. 37

Figure 42. Chart. Joint LTE for slab number 4 ............................................................................. 38

Figure 43. Graph. LTE under fatigue test for slab number 4 (0 to 5 million cycles) ................... 38

Figure 44. Photo. Dowel-concrete interface condition in slab number 4 after 5 million 

load cycles ..................................................................................................................................... 39

Figure 45. Chart. Joint LTE for slab number 5 ............................................................................. 40

Figure 46. Graph. LTE under fatigue test for slab number 5 (0 to 5 million cycles) ................... 40

Figure 47. Diagram. Case one—60.96-cm (2-ft) base material removal under loaded side of 

slabs............................................................................................................................................... 43

Figure 48. Diagram. Case two—30.48-cm (1-ft) base material removal under both sides of 

slabs............................................................................................................................................... 43

Figure 49. Chart. RD for pumping tests (case one—60.96-cm (2-ft) base removal) ................... 44

Figure 50. Chart. LTE for pumping tests (case one—60.96-cm (2-ft) base removal) .................. 44

Figure 51. Graph. RD for pumping tests under 13.345 kN (3 kips) loading (case two— 

30.48-cm (1-ft) base removal under both slabs) ........................................................................... 46

Figure 52. Graph. LTE for pumping tests under 13.345 kN (3 kips) loading (case two— 

30.48-cm (1-ft) base removal under both slabs) ........................................................................... 46

Figure 53. Graph. Strain gauge reading in slab 1 (2.54-cm (1.0-inch) diameter at 15.24-cm 

(6-inch) spacing c/c) from static test to 1 million cycles under HS25 loading) ........................... 47

Figure 54. Chart. Strain gauge reading in slab number 4 (3.81-cm (1.5-inch) diameter at 

30.48-cm (12-inch) spacing c/c) from static test under HS25 loading ......................................... 48

Figure 55. Photo. Dowel installation at location 1 of corridor H, Route 250, Elkins, WV .......... 49

Figure 56. Diagram. FRP dowel positions at location 1 of corridor H, Route 250, Elkins, WV .... 50

Figure 57. Photo. FRP dowel bars at location 2 of corridor H, Route 219, Elkins, WV .............. 50

Figure 58. Diagram. FRP dowel positions at location 2 of corridor H, Route 219, Elkins, WV .... 51

Figure 59. Photo. FRP dowel bars bonded with strain gauges at loaded and unloaded sides ...... 52

Figure 60. Photo. Embeddable concrete strain gauge with dowels .............................................. 52

Figure 61. Photo. FRP dowels in dowel basket ............................................................................ 53

Figure 62. Photo. Paving operation in progress ............................................................................ 53

Figure 63. Photo. FRP dowel bars being covered by concrete ..................................................... 54

Figure 64. Photo. Dial gauges for measuring pavement deflection under truck loading .............. 56

Figure 65. Photo. Data acquisition system used for field tests ..................................................... 56

Figure 66. Diagram. Dowel A1 (3.81-cm (1.5-inch) diameter, 22.86-cm (9-inch) spacing); 

refer to figure 58 ........................................................................................................................... 58

Figure 67. Chart. Strains in dowel during loading and unloading cases for gauge A1-LT 

(3.81-cm (1.5-inch) diameter, 22.86-cm (9-inch) spacing) .......................................................... 58

Figure 68. Diagram. Dowel A2 (3.81-cm (1.5 inch) diameter, 30.48-cm (12-inch) spacing); 

refer to figure 58 ........................................................................................................................... 59

Figure 69. Chart. Strains in dowel during loading and unloading cases for gauge A2-LT 

(3.81-cm (1.5-inch) diameter, 30.48-cm (12-inch) spacing); refer to figure 58 ........................... 59

Figure 70. Diagram. Dowel C5 (2.54-cm (1.0-inch) diameter, 15.24-cm (6-inch) spacing); 

refer to figure 58 ........................................................................................................................... 60
ix 

Figure 71. Chart. Strains in dowel during loading case for gauge C5-U1 (2.54-cm (1.0-inch) 

diameter, 15.24-cm (6-inch) spacing); refer to figure 58 .............................................................. 60

Figure 72. Diagram. Dowel C6 (2.54-cm (1.0-inch) diameter, 20.32-cm (8-inch) spacing); 

refer to figure 58 ........................................................................................................................... 61

Figure 73. Chart. Strains on dowel during loading case for gauge C6-U1 (2.54-cm (1.0-inch) 

diameter, 20.32-cm (8-inch) spacing); refer to figure 58 .............................................................. 61

Figure 74. Chart. Strain from gauge A1-LT (3.81-cm (1.5-inch)-diameter FRP dowel at 

22.86-cm (9-inch) spacing) from dynamic tests ........................................................................... 62

Figure 75. Chart. Strain from gauge A2-LT (3.81-cm (1.5-inch)-diameter FRP dowel at 

30.48-cm (12-inch) spacing) from dynamic tests ......................................................................... 63

Figure 76. Photo. WVDOT truck used for field tests ................................................................... 65

Figure 77. Photo. WVDOT truck positioned near a joint for the test ........................................... 66

Figure 78. Photo. Two LVDTs measuring pavement deflections across a joint .......................... 66

Figure 79. Photo. Measuring distance from tire to LVDTs (when loading is away from the 

selected dowel) .............................................................................................................................. 67

Figure 80. Chart. Deflection on pavement joint 3 (with 3.81-cm (1.5-inch)-diameter and 

30.48-cm (12-inch)-spacing FRP dowels) under loading ............................................................. 68

Figure 81. Chart. Deflection on pavement joint 2 (with 3.81-cm (1.5-inch)-diameter and 

22.86-cm (9-inch)-spacing FRP dowels) under unloading ........................................................... 68

Figure 82. Chart. Deflection on pavement joint 2 (with 3.81-cm (1.5-inch)-diameter and 

22.86-cm (9-inch)-spacing FRP dowels) under loading ............................................................... 69

Figure 83. Chart. Deflection on pavement joint 5 (with 2.54-cm (1.0-inch)-diameter and 

20.32-cm (8-inch)-spacing FRP dowels) under loading ............................................................... 69

Figure 84. Chart. Deflection on pavement joint 6 (with 2.54-cm (1.0-inch)-diameter and 

15.24-cm (6-inch)-spacing FRP dowels) under loading ............................................................... 70

Figure 85. Graph. Comparison of LTE from field test (average value was used for joint 2) ....... 72

Figure 86. Graph. Comparison of RD from field test (average value was used for joint 2) ......... 73

Figure 87. Photo. Locations of FRP and steel-doweled pavement joints ..................................... 75

Figure 88. Photo. Drilling holes for inserting dowels ................................................................... 76

Figure 89. Photo. FRP dowels in position .................................................................................... 76

Figure 90. Photo. Steel dowels in position ................................................................................... 77

Figure 91. Photo. Concrete placement and vibration .................................................................... 77

Figure 92. Photo. Data acquisition recording strain readings ....................................................... 78

Figure 93. Chart. Strain from FRP dowels in rehabilitated pavement .......................................... 79

Figure 94. Chart. Strain from steel dowel in rehabilitated pavement ........................................... 80

Figure 95. Diagram. Semi-infinite beam on an elastic foundation ............................................... 84

Figure 96. Diagram. Slope and deflection of dowel at joint face ................................................. 85

Figure 97. Diagram. Load transfer distribution proposed by Friberg ........................................... 87

Figure 98. Diagram. Load transfer distribution proposed by Tabatabaie et al ............................. 88

Figure 99. Diagram. Most critical dowel at the edge of a slab ..................................................... 88

Figure 100. Diagram. RD between concrete slabs (Porter and Guinn) ........................................ 89

Figure 101. Diagram. Expansion joint model used for theoretical calculation ............................ 92

Figure 102. Diagram. Steps for calculating critical dowel load, joint RD, and bearing stress in 

JPCP .............................................................................................................................................. 94

Figure 103. Diagram. Generalized effective dowels for load distribution ................................... 95

Figure 104. Diagram. Most critical load distribution on effective dowels ................................... 95
x 

Figure 105. Diagram. Pavement contraction joint model ............................................................. 98

Figure 106. Diagram. Expansion joint model used for theoretical calculation .......................... 101

Figure 107. Diagram. Most critical load distribution on effective dowels ................................. 103

Figure 108. Chart. Dowel deflected shape (2.54-cm (1.5-inch) diameter) ................................. 110

Figure 109. Chart. Dowel deflected shape .................................................................................. 114

Figure 110. Photo. Lab test of timber tie with FRP dowel bar as the load transfer device ........ 133

Figure 111. Diagram. Four timber test cases .............................................................................. 134

Figure 112. Diagram. Rosette strain gauges ............................................................................... 134

Figure 113. Chart. Plot for longitudinal strain gauges (case I-A and case I-B) .......................... 136

Figure 114. Chart. Load versus deflection (inches) of timber tie for case I-A ........................... 140

Figure 115. Chart. Load deflection (arm with regular gauge) for case I-B ................................ 140

Figure 116. Graph. Components of RD for dowel types A (2.54-cm (1.0-inch) diameter) and 

B (3.81-cm (1.5-inch) diameter), with k = 11.072 kg/cm3 (400 pci), fc' = 31.026 MPa 

(4,500 psi), joint width = 0.635 cm (0.25 inch), and Gd = 2.8 × 103

 MPa (0.4 × 106 psi) .......... 143

Figure 117. Graph. Components of RD for dowel types A (2.54-cm (1.0-inch) diameter) and 

B (3.81-cm (1.5-inch) diameter), with k = 11.072 kg/cm3

 (400 pci), fc' = 31.026 MPa 

(4,500 psi), joint width = 0.635 cm (0.25 inches), and Gd = 5.17 × 103 MPa (0.75 × 106 psi) .. 143
xi 

LIST OF TABLES 

Table 1. Modulus of elasticity (MOE) test results of FRP rod specimens—ASTM D3916 .......... 8

Table 2. Shear test results of FRP rod specimens—single-shear fixture ........................................ 8

Table 3. Dowel details in specimens ............................................................................................. 15

Table 4. Details of static testing .................................................................................................... 18

Table 5. Details of fatigue testing ................................................................................................. 18

Table 6. Parameters of dowel groups ............................................................................................ 19

Table 7. Cracks in the tested slabs ................................................................................................ 21

Table 8. Static load applied for specimen 1 .................................................................................. 22

Table 9. Load applied for fatigue tests on slab number 1 ............................................................. 22

Table 10. Load applied for fatigue tests on specimen 2 ............................................................... 25

Table 11. Load applied for fatigue tests on slab number 3 ........................................................... 27

Table 12. Load applied for fatigue tests on slab number 4 ........................................................... 28

Table 13. Load applied for fatigue tests on slab number 5 ........................................................... 30

Table 14. RD of group 1 from static tests ..................................................................................... 31

Table 15. RD of group 1 from fatigue tests .................................................................................. 31

Table 16. RD of group 2 from static tests ..................................................................................... 32

Table 17. RD of group 2 from fatigue tests .................................................................................. 32

Table 18. LTE of group 1 from static tests ................................................................................... 41

Table 19. LTE of group 1 during fatigue tests .............................................................................. 41

Table 20. LTE of group 2 from static tests under corresponding HS25 load ............................... 42

Table 21. LTE of group 2 from fatigue tests ................................................................................ 42

Table 22. Evaluation of pumping issue under 44.482 kN (10 kips) loading ................................ 45

Table 23. Evaluation of pumping issue under 13.345 kN (3 kips) loading .................................. 45

Table 24. Parameters of the field test at location 2, July 2002 ..................................................... 55

Table 25. Joint details used for analysis ....................................................................................... 57

Table 26. Summary of FRP dowel strain during loading and unloading ...................................... 63

Table 27. Parameters of the field test, June 2003 ......................................................................... 65

Table 28. Pavement joint for deflection analysis .......................................................................... 67

Table 29. Summary of joint deflection under maximum loading force ........................................ 71

Table 30. Values for LTE comparison from field test .................................................................. 72

Table 31. Comparison of RD values from field test ..................................................................... 73

Table 32. Comparing joint 2 and joint 3 ....................................................................................... 73

Table 33. Calculation summaries for 3.81-cm (1.5-inch)-diameter dowel (k = 11.072 kg/cm3 

(400 pci), fc′ = 31.026 MPa (4,500 psi)) ..................................................................................... 109

Table 34. Peak bearing stress and average bearing stress in dowel (3.81-cm (1.5-inch) 

diameter at 30.48 cm (12 inches) c/c) downward area ............................................................... 109

Table 35. Peak bearing stress and average bearing stress within 2.54-cm (1-inch) dowel 

(3.81-cm (1.5-inch) diameter at 30.48 cm (12 inches) c/c) length from joint face ..................... 110

Table 36. Calculation summaries for 2.54-cm (1.0-inch)-diameter dowel (k = 11.0719 kg/cm3

(400 pci), fc′ = 31.026 MPa (4,500 psi)) ..................................................................................... 113

Table 37. Peak bearing stress and average bearing stress in dowel ((2.54-cm (1.0-inch) 

diameter at 15.24 cm (6 inches) c/c) downward area ................................................................. 113

Table 38. Peak bearing stress and average bearing stress within 2.54-cm (1-inch) dowel 

(2.54-cm (1.0-inch) diameter at 15.24 cm (6 inches) c/c) length from joint face ....................... 114
xii 

Table 39. Comparison of experiments versus theory for slab RD in static testing under 

HS25 loading .............................................................................................................................. 117

Table 40. Strains during loading and unloading on case I-A ...................................................... 135 

Table 41. Strains during loading and unloading on case I-B ...................................................... 136 

Table 42. Strains during loading and unloading on case II-A .................................................... 137 

Table 43. Deflections of timber tie on case I-A .......................................................................... 138 

Table 44. Deflections of timber tie on case I-B .......................................................................... 139 

Table 45. RD with low dowel shear modulus (Gd = 2.758 × 103 MPa (0.4 × 106 psi)) ............. 142

Table 46. RD with high dowel shear modulus (Gd = 5.17 × 103 MPa (0.75 × 106 psi)) ............ 142

Table 47. FWF and FVF for FRP dowel with 2.54-cm (1.0-inch) diameter .............................. 145

Table 48. FWF and FVF for FRP dowel with 3.81-cm (1.5-inch) diameter .............................. 145

 
1 

CHAPTER 1. INTRODUCTION 

GENERAL REMARKS 

U.S. highways and roads made of jointed plain concrete pavement (JPCP) use load transfer 

devices, called dowels, across joints of a series of contiguous concrete slabs. Joints allow the 

movement and deformation of pavement to occur under mechanical loading and thermal 

variations. Joints may either be parallel to traffic (longitudinal joints) or perpendicular to traffic 

(transverse joints). Typical problems of jointed concrete pavement without an effective loadtransfer device include faulting, pumping, and corner breaks. 

As the American Association of State Highway and Transportation Officials (AASHTO) 

reported, pavement joints supported with dowels have a longer service life than joints without 

dowels.(1) Over time, traffic traveling over a joint may crush the concrete surrounding the dowel 

bar and cause voids due to excessive bearing stresses between the dowel and surrounding 

concrete. Concrete crushing may take place due to stress concentration where the dowel contacts 

concrete at the joint face directly above and below the dowel. Looseness of dowel support can 

decrease the load transfer efficiency (LTE) across the joint and accelerate pavement damage.(2)

Corrosion of the dowel bar can potentially bind or lock the joint. When locking of the joint 

occurs, no thermal expansion is allowed, and new cracks parallel to the joint are formed directly 

behind the dowel bars in the concrete. As temperature decreases, contraction of the concrete 

widens the new cracks, leading to reduction of load transfer. Once there is no load transferred 

across the joint, the load is then transferred to the subgrade, and differential settlement occurs in 

the adjacent slabs. Differential settlement of the adjacent slabs creates uneven surface and 

discontinuity at the joints, making vehicle travel uncomfortable and leading to slab repair or 

replacement. 

Currently, steel dowels, typically epoxy coated with a diameter of 2.54 or 3.81 cm (1.0 or 

1.5 inches) and length of 45.72 cm (18 inches), are widely used in JPCP. However, this coating 

is usually nicked or scraped before installation, leading to dowel corrosion and deterioration 

(figure 1). Fiber reinforced polymer (FRP) dowel bars, which are resistant to corrosive 

environments, can be used as effective load transfer mechanisms in JPCP. Currently, polymer 

matrix composites such as FRP are being used in a broad range of structural applications within 

the aerospace, automotive, marine, and construction industries due to their superior strength-toweight ratio and high corrosion resistance.(3)

For this research, response of concrete pavement with FRP dowels was investigated through 

laboratory experiments and field implementation. 
2 

Figure 1. Photo. Exposed failures with rusted dowel bars (Washington State Department of 

Transportation Pavement Guide).(4)

OBJECTIVES 

The main objectives of this study were as follows: 

• To evaluate 3.81-cm (1.5-inch)- and 2.54-cm (1.0-inch)-diameter FRP dowel bars spaced at 

different intervals as load transferring devices in JPCP under HS25 static and fatigue loads 

and to compare their response (relative deflection (RD) and LTE) with JPCP consisting of 

steel dowels under laboratory and field conditions. 

• To evaluate the performance (strain and deflection) of JPCP rehabilitated with FRP and steel 

dowels. 

• To model FRP and steel dowel response and that of the pavement in terms of dowel 

maximum bending deflection, RD, and bearing stress. 

SCOPE 

Details of laboratory tests conducted at West Virginia University (WVU) structural laboratory 

were as follows: 

• Two jointed concrete slabs with 3.81-cm (1.5-inch)-diameter FRP dowels and 30.48-cm 

(12-inch)-slab depth were tested under static loads during preliminary static load 

investigation. 

• Five jointed concrete slabs with 3.81- and 2.54-cm (1.5- and 1.0-inch) steel and FRP dowels 

with spacings of 30.48 and 15.24 cm (12 and 6 inches) were tested under static and fatigue 

loads corresponding to HS25 load and 1.5 times HS25 load. The slab depth was 27.94 cm 

(11 inches) for all five slabs, similar to field installation depth. 
3 

• Using identical slab thickness, fc′, joint depth, and joint width, the pavement performance 

(LTE, RD, and dowel strain) with FRP and steel dowels was evaluated with respect to the 

following: 

o Dowel diameter. 

o Dowel spacing. 

FRP dowel bars were field installed in new highway JPCP construction on Route 219, Elkins, 

WV. Both 3.81- and 2.54-cm (1.5- and 1.0-inch)-diameter FRP dowels were installed in the field, 

and the dowel spacings that were used were 15.24, 20.32, 22.86, and 30.48 cm (6, 8, 9, and 

12 inches). Two field tests were conducted, and results were analyzed and are discussed in this 

report. 

FRP dowel bars with 3.81-cm (1.5-inch) diameters were installed for pavement rehabilitation 

near the intersection of Routes 857 and 119, University Avenue, Morgantown, WV. Dowel 

strains due to regular traffic were analyzed and are discussed in this report. 

Analysis and discussions corresponding to theoretical calculations are provided for four different 

examples of pavements with FRP and steel dowels in terms of dowel diameter, spacing, dowel 

material properties, joint width, and base material properties. 

The remainder of this report is organized into the following chapters and appendices: 

• Chapter 2 deals with the literature review. 

• Chapter 3 describes materials and laboratory test setup used in this research. 

• Chapter 4 discusses experimental results from laboratory tests. 

• Chapter 5 presents field installation, field load test results, and discussions. 

• Chapter 6 presents theoretical evaluations. 

• Chapter 7 provides the summary and conclusions of this research, including suggestions for 

future research. 

• Appendix A describes a preliminary test on timber ties consisting of an FRP dowel as the 

load transfer device. 

• Appendix B analyzes and evaluates the effects of FRP dowel shear modulus on pavement RD. 

• Appendix C describes the details of burnout tests for determining fiber weight fraction (FWF) 

and fiber volume fraction (FVF) of FRP dowels with 2.54- and 3.81-cm (1.0- and 1.5-inch) 

diameters.

5 

CHAPTER 2. LITERATURE REVIEW 

INTRODUCTION 

In JPCP highways and roads, inadequate load transfer across the joint will cause substantially 

higher stresses and deflections due to joint loading than those due to interior loading. A dowel 

bar transfers part of an applied wheel load from the loaded slab across the joint to the adjacent 

unloaded slab. Load transfer through dowel bars significantly reduces stresses and deflections 

due to joint loading, leading to minimized faulting and pumping (figure 2). Faulting is a 

difference in elevation across the joint of two slabs, while pumping is defined as the expulsion of 

subgrade material through joints and along the edges of the pavement.(5)

Figure 2. Typical pavement problems—faulting and pumping. 

LITERATURE REVIEW FINDINGS 

FRP dowels have not been widely used in concrete pavements for highways. However, a number 

of projects in the United States and Canada have used these composite materials for highway 

pavement on an experimental basis. 

In 1983, the Ohio Department of Transportation installed several FRP dowel bars to evaluate 

long-term performance in sections of Interstate 77 in Guernsey County and Ohio State Route 7 in 

Belmont County. In 1998, the Market Development Alliance of the composites industry 

organized the extraction and testing of samples of these dowel bars. Glass fiber reinforced 

polymer (GFRP) dowel bars were found to be virtually unaffected by approximately 15 years of 

field service and exposure in pavement service. 

In 1997, FRP dowel bars were installed in a high-performance pavement project on the U.S. 

Route 65 bypass near Des Moines, IA. Lengths of the pavement sections with FRP dowels were 

134.11 and 127.10 m (440 and 417 ft) with 6.10-m (20-ft) joint spacing (skewed) and dowel bars 

on 30.48- and 20.32-cm (12- and 8-inch) spacing, respectively. Indications are that the FRP 

dowels have been performing well. Additional alternative dowel bar projects utilizing FRP 

dowels have been installed in Illinois, Iowa, Kansas, Minnesota, Ohio, Wisconsin, and Manitoba. 

Fault

Pumping of water

through joint
6 

Brown and Bartholomew found that FRP dowels made of vinyl ester resins compared well with 

steel dowels in the scaled model tests.(6) Experimental load transfer percentages were in 

agreement with theoretical values and fell within the 35–40 percent range predicted for standard 

joints under typical subgrade conditions. They recommend an approximately 20–30 percent 

increase in dowel diameter to maintain deflections, concrete bearing stresses, and load transfer 

percentages at comparable levels with joints containing steel dowels.(6)

Ahmed et al. from the University of Manitoba, Canada, have conducted research on GFRP 

dowels.(7) In their experimental program, a round GFRP dowel bar having a 38-mm (1.5-inch) 

diameter and a concrete-filled GFRP pipe having a 60-mm (2.36-inch) outside diameter were 

evaluated in a laboratory setting and in a field implementation. The field test section was 

constructed on a regional highway in Winnipeg, Manitoba.(7)

They concluded that GFRP dowels subjected to Falling Weight Deflectometer tests in the field 

showed that LTEs of GFRP dowels were comparable to those produced by steel dowels, 

provided that the diameter of the GFRP dowel was 20–30 percent larger than the steel dowel. 

The larger diameter resulted in a reduction in bearing stresses that in turn reduced the potential 

for faulting. 

Tests conducted by Eddie et al. showed the joint effectiveness of GFRP dowels to be in the range 

of 86–100 percent using a weak subgrade, and 90–97 percent using a stiff subgrade.(8) An 

American Concrete Pavement Association (ACPA) criterion for successful joint load transfer is 

75 percent.(8)

Porter and other researchers at Iowa State University studied the use of GFPR dowels for JPCP 

with contraction.(9) They concluded the following: 

• The 3.81-cm (1.5-inch)-diameter GFRP dowels spaced at 30.48-cm (12-inch) centers were 

inadequate in transferring load for the anticipated design life of the pavement. 

• The 3.81-cm (1.5-inch)-diameter GFRP dowels spaced at 15.24-cm (6-inch) centers were 

effective in transferring load over the anticipated design life of the pavement.(9)

The literature review indicates contradictory conclusions on the LTE of 3.81-cm (1.5-inch) FRP 

dowels. Suggestions are also provided by the researcher to increase dowel bar diameter from 

3.81 cm (1.5 inches) to 4.45 cm (1.75 inches). Some researchers have noted increased RD with 

an increased diameter. Hence, it was decided to utilize 3.81- and 2.54-cm (1.5- and 1.0-inch) 

dowel diameters in this research with 69.47 percent and 72 percent FWF, respectively. Chapter 3 

describes materials and laboratory test setup used in this research.
7 

CHAPTER 3. MATERIALS, EQUIPMENT, AND LABORATORY TESTING 

PROCEDURES 

INTRODUCTION 

Mechanical properties of dowel bars affect the behavior and performance of JPCP provided with 

FRP and steel dowels. This chapter discusses mechanical properties of FRP and steel dowels and 

test setup in the Major Units Laboratory of WVU. Seven full-scale JPCPs (two with a dimension 

of 30.48 by 30.48 by 304.8 cm (12 by 12 by 120 inches) and five with a dimension of 30.48 by 

27.94 by 304.8 cm (12 by 11 by 120 inches) were cast with simulated contraction or sawcut 

joints. The specimens were subjected to both static load and fatigue load with a frequency of 

about 4.0 Hz. 

MATERIAL PROPERTIES 

Class K concrete (25.856 and 31.026 MPa (3,750 and 4,500 psi) and two different diameters 

(3.81 and 2.54 cm (1.5 and 1.0 inch)) of GFRP dowel and epoxy-coated steel dowels were used 

for casting the concrete pavements in the structural laboratory. Relevant material properties are 

provided in this section. 

The two slabs that were used for preliminary testing consisted of fc′ of 25.856 MPa (3,750 psi); 

the remainder of the five slabs consisted of fc′ of 31.026 MPa (4,500 psi), as found through 

cylinder tests. 

GFRP Dowels 

GFRP dowels provided by independent manufacturers are pultruded with continuous E glass 

filaments and polyester resin. Typically, filaments are drawn through a resin bath, sized by an 

appropriate die, to form the dowel bar. An ultraviolet inhibitor is added to the resin to resist 

effects of sunlight. Dowels with 3.81- and 2.54-cm (1.5- and 1.0-inch) diameters were used in 

this project. Other researchers have commented on using 4.45-cm (1.75-inch)-diameter FRP 

dowel bars instead of 3.81-cm (1.5-inch)-diameter dowel bars. However, researchers have noted 

that increased bar diameter result in larger RD. Hence, it was decided to use lower diameter bars 

in this research.(9)

Figure 3 shows two types of GFRP dowels used in this research. Table 1 and table 2 show 

properties of FRP bars listed by the manufacturer. 
8 

Figure 3. Photo. FRP dowels (2.54 and 3.81 cm (1.0 and 1.5 inches) in diameter). 

Table 1. Modulus of elasticity (MOE) test results of FRP rod specimens—ASTM D3916 

Type 

Nominal 

Diameter 

(inches) 

Actual 

Diameter 

(inches) 

Area 

Square 

(inches)

Ultimate 

Load 

(lbs) 

Tensile 

Stress 

(psi) 

Elongation 

(percent) 

MOE 

(Msi) 

A 1.0000 0.9713 0.7394 66,539 89,986 0.094 6.0

1.0000 0.9700 0.7390 65,204 88,235 0.091 6.0

Average 1.0000 0.9707 0.7392 65,872 89,111 0.093 6.0

B 1.5000 1.4932 1.7512 134,440 76,772 0.219 5.2

1.5000 1.4933 1.7514 137,000 78,226 0.179 5.0

Average 1.5000 1.4933 1.7513 135,720 77,499 0.199 5.1

1 inch = 2.54 cm 

1 inch2

 = 2.54 cm2

1 psi = 0.006895 MPa 

1 million psi (Msi) = 6.895 GPA 

Table 2. Shear test results of FRP rod specimens—single-shear fixture. 

Type 

Nominal 

Diameter 

(inches) 

Actual 

Diameter 

(inches) 

Area 

Square 

(inches) 

Ultimate 

Load (lbs) 

Shear 

Stress 

(psi) 

A 

1.0000 0.9703 0.7390 28,600 38,700 

1.0000 0.9700 0.7380 30,300 41,060 

1.0000 0.9702 0.7390 27,200 36,810 

Average 1.0000 0.9702 0.7387 28,700 38,857 

B 1.5000 1.4923 1.7490 33,982 19,429 

1.5000 1.4935 1.7519 31,782 18,142 

Average 1.5000 1.4929 1.7505 32,882 18,786 

1 inch = 2.54 cm 

1 inch2

 = 2.54 cm2

1 lb = 0.454 kg 

1 psi = 0.006895 MPa 
9 

Steel Dowels 

The steel dowels used in this research, shown in figure 4, were grade 40 plain uncoated steel or 

epoxy-coated steel. Dowels with 3.81- and 2.54-cm (1.5- and 1.0-inch) diameters were used for 

laboratory experiments and field installation. 

Figure 4. Photo. Steel dowels 3.81 and 2.54 cm (1.5 and 1.0 inches) in diameter. 

Concrete 

Class K ready-mixed concrete was used for laboratory slab casting. The compressive strength of 

the concrete was 25.856 MPa (3,750 psi) for 30.48-cm (12-inch)-thick slabs and 31.026 MPa 

(4,500 psi) for 27.94-cm (11-inch)-thick slabs. Concrete was poured in formwork, and forms 

were removed after 24 hours. The concrete beams were cured 28 days by wet burlap and plastic 

sheet covering. 

Base 

To simulate a stiff subgrade used in the field, a base layer of limestone aggregates was prepared 

and compacted to a depth of 40.64 cm (16 inches) in a wood-framed bin shown in figure 5. The 

modulus of subgrade reaction k was determined from plate loading tests in the laboratory. Based 

on the measured values, an average of 11.072 kg/cm3

 (400 lbs/pci) was used for all tests 

employing aggregate base. The value was also applied to the theoretical calculations. 

FORMWORK 

Figure 5 and figure 6 show wood formworks made for casting concrete slabs in the laboratory. 

TEST SETUP 

Specimen Fabrication 

Seven different slabs were cast with FRP and steel dowels using different spacing and diameters. 
10 

Figure 5. Photo. Wood formwork. 

Wood 

Formwork

0.25" steel 

plate

Joint of 

two slabs

Formwork is symmetrical about the joint plan (unit: inch)

60.00

12.00

0.25

11.00 3.75

1 inch = 2.54 cm 

Figure 6. Diagram. Dimensions of formwork. 
11 

Material Preparations 

FRP and steel dowels were prepared with slots at locations where strain gauges were going to be 

placed. 

Uniaxial strain gauges were bonded to dowels at the slot position shown in figure 7. Strain 

gauges were protected using M-Coat-J (polysulfide liquid polymer). 

1 inch = 2.54 cm 

Figure 7. Diagram. Trimmed dowel bar. 

Pavement Slab Casting 

The inside walls of the wood formworks were oiled so that the concrete pavement slabs could be 

easily demolded. Strain gauge instrumented dowels were then placed in dowel baskets to 

properly center them in the joint (figure 8). A steel plate with 0.635-cm (0.25-inch) thickness 

was placed in the middle to simulate a contraction or sawcut joint in the concrete pavement 

(figure 5, figure 6, and figure 8). 

Figure 9 through figure 12 show the slab casting. Class K concrete conforming to the West 

Virginia Department of Transportation (WVDOT), Department of Highway (DOH) specification 

was used for casting (figure 11). Concrete cylinders were cast simultaneously to obtain concrete 

compressive strength. Twenty-four hours after casting the beams and cylinders, curing was 

carried out using wet burlaps. 
12 

Figure 8. Photo. Instrumented dowels and steel plate positioned in the wood formwork. 

Figure 9. Photo. Placing concrete into the formwork. 
13 

Figure 10. Photo. Dowel being covered by concrete. 

Figure 11. Photo. Casting concrete cylinders. 
14 

Figure 12. Photo. Surface finished specimens. 

Test Specimens 

Two specimens with dimensions of 30.48 by 30.48 by 304.8 cm (12 by 12 by 120 inches) 

(figure 13) were cast for preliminary tests. Only FRP dowels were used as load transfer devices 

in these two specimens. 

specimen is symmetrical about the joint plan (unit: inch)

12.00

FRP or steel 

dowel in the 

mid of joint

Joint of two 

slabs

60.00

3.75

0.25

12.00

6.0

1 inch = 2.54 cm 

Figure 13. Diagram. Concrete slabs for preliminary tests. 
15 

Five different concrete slabs were cast with FRP and steel dowels with different spacings and 

diameters (table 3). Two embeddable strain gauges were positioned vertically on both sides of a 

dowel across the joint to measure concrete strain at loaded side and unloaded side. Details of 

concrete specimens and dowels are provided in figure 14, figure 15, and table 3. 

Table 3. Dowel details in specimens. 

Specimen 

Number 

Slab 

Depth 

(inches)

Dowel 

Material 

Dowel 

Diameter 

(inches) 

Spacing 

(inches) 

c/c 

Number of 

Dowels in 

Each 

Specimen 

Preliminary 

group 

PG-1 12 FRP 1.5 12 1 PG-2 FRP 1.5

Group 1 

1 

11

Steel 1.0

2 FRP 1.0 6 2

3 FRP 1.5

Group 2 4 11 FRP 1.5 12 1 5 Steel 1.5

c/c = Center to center 

1 inch = 2.54 cm 

specimen is symmetrical about the joint plan (unit: inch)

Joint of two 

slabs

6.00

FRP or steel 

dowel

3.75

11.00

5.50

0.25

60.00

12.00

1 inch = 2.54 cm 

Figure 14. Diagram. Concrete slabs containing two dowels. 
16 

FRP or steel 

dowel in the 

mid of joint

5.50

0.25

specimen is symmetrical about the joint plan (unit: inch)

12.00

60.00

Joint of two 

slabs

3.75

11.00

1 inch = 2.54 cm 

Figure 15. Diagram. Concrete slabs containing only one dowel. 

Test Setup and Instrumentation 

Jointed concrete slabs were placed on an aggregate base inside a wooden box to simulate field 

conditions. The base was 15.24 cm (6 inches) high, 45.72 cm (18 inches) wide, and 304.8 cm 

(120 inches) in length. The modulus of subgrade reaction k was obtained from tests on this base 

through load application on a standard steel plate.(10)

Pavement load was applied on one side of the joint (figure 16 and figure 17) using a 

244.65-kN (55-kip) hydraulic actuator system through a controller. A 0.635-cm (0.25-inch)-thick 

steel plate 25.4 by 40.64 cm (10 by 16 inches) was connected to the actuator to simulate the load 

from a dual tire wheel load. An additional neoprene pad was used between the steel plate and the 

concrete surface to prevent any local damage during the test. Two calibrated linear variable 

differential transformers (LVDTs) were used to measure joint deflections at the loaded and 

unloaded sides of the joint. Strain gauges, LVDTs, and the load cell from the actuator were 

connected to a data acquisition system to automatically record data during the tests. 
17 

Figure 16. Photo. Experimental setup. 

Figure 17. Photo. LVDTs positioned on both sides of the joint. 

Static Testing 

Load was applied at different increments to simulate an HS25 wheel load and/or higher load. 

Deflections and strains were recorded automatically by the data acquisition system. Details of the 

load applied on different concrete slabs are shown in table 4. 
18 

Table 4. Details of static testing. 

Specimen Number Load Range 

Slab number 1 0–12.5 kips

Slab number 2 0–12.5 kips

Slab number 3 0–12.5 kips

Slab number 4 0–11 kips

Slab number 5 0–11 kips

1 kip = 4.448 kN 

Fatigue Testing

The load from the hydraulic actuator system was set at the required range of fatigue cycles 

(table 5) and was applied using a sine wave. After every 1 million cycles, a static test was 

conducted on the pavement system to measure strain and deflections. Details of fatigue tests are 

provided in table 5.

Table 5. Details of fatigue testing. 

Specimen 

Number Load and Range (kips) 

Number of 

cycles (million) 0–1 1–1.25 1.25–2 2–3 3–4 4–5

Slab number 1 2–12.5 2–18.75 2–18.75 2–18.75 2–18.75 2–18.75

Slab number 2 2–12.5 2–18.75 2–18.75 — — —

Slab number 3 2–12.5 2–12.5 — — — —

Slab number 4 2–11 2–11 2–11 2–11 2–11 2–11

Slab number 5 2–11 2–11 2–11 2–11 2–11 2–11

— No loading at corresponding cycles. 

For specimens 1, 2, and 3, an overload factor of 1.5 (i.e., 1.5 by HS25) was used to apply higher load during 

fatigue tests after 1 million cycles. 

1 kip = 4.448 kN

It should be noted that slabs number 1 through 3 had 55.60 kN (12.5 kips), and slabs number 4 

and 5 had 48.93 kN (11 kips) of loading corresponding to HS25 loading as described in chapter 6 

of this report. 
19 

CHAPTER 4. EXPERIMENTAL RESULTS AND DISCUSSION 

INTRODUCTION 

Experimental setup used in the Major Units Laboratory was previously discussed in chapter 3. 

This chapter discusses the experimental results of five jointed concrete slabs with FRP or steel 

dowels. Parameters evaluated in these tests under static and fatigue loads included the following: 

• LTE. 

• RD between loaded and unloaded pavement. 

• Strain on dowels. 

Before discussing these three parameters, joint crack patterns observed in the tests are presented. 

Joint crack patterns have significant effects on LTE, RD, and dowel strains. 

Parameters of two preliminary tests conducted on two pavement slabs with FRP dowels and 

actual main tests are listed in table 6. Slabs with 15.24-cm (6-inch) spacing were placed in 

group 1, whereas slabs with 30.48-cm (12-inch) spacing were placed in group 2. 

Table 6. Parameters of dowel groups. 

Group 

Slab 

Number 

CentertoCenter 

Spacing 

(inches) 

Number 

of 

Dowels 

in Slab 

Concrete 

Strength 

(psi) 

Dowel 

Material 

Dowel 

Diameter 

(inches) 

Preliminary 

group 

PG-1 12 1 3,500 FRP 1.5 PG-2 

Group 1 

1 

6 2 4,500

FRP 1.0

2 Steel 1.0

3 FRP 1.5

Group 2 4 12 1 4,500 FRP 1.5

5 Steel 1.5

1 inch = 2.54 cm 

1 psi = 0.006 895 MPa 

JOINT CRACK PATTERNS OBSERVED IN LABORATORY TESTS 

Cracks in JPCP specimens occurred at two locations: one was right at the joint, and the other was 

directly under the loading zone, close to dowel edge. Figure 18 through figure 20 show the 

following three types of crack patterns observed in tests (also refer to table 7): 

• Type I—Crack occurred only in the joint (figure 18). 

• Type II—Cracks occurred at joint and loading zone close to dowel edge (figure 19). 
20 

• Type III—Crack occurred away from the joint at the dowel edge in the loading zone 

(figure 20). 

Figure 18. Photo. Typical crack observed in slabs number 1, 4, and 5 (table 7). 

Figure 19. Photo. Crack observed in slab number 2 (table 7). 
21 

Figure 20. Photo. Typical crack observed in slab number 3 (table 7). 

Table 7. Cracks in the tested slabs. 

Group 

Number Specimen 

Dowel 

Material

Concrete 

Strength 

(psi) 

Dowel 

Diameter/ 

Spacing 

(inches) 

Number 

of Dowels 

in 

Specimen 

Crack 

Pattern 

Preliminary 

group 

PG-1 FRP 3,500 1.5 at 12 c/c 1 I PG-2 

Group 1 

Slab number 1 FRP 

4,500

1.0 at 6 c/c

2 

I 

Slab number 2 Steel 1.0 at 6 c/c II 

Slab number 3 FRP 1.5 at 6 c/c III 

Group 2 Slab number 4 FRP 4,500 1.5 at 12 c/c 1 I 

Slab number 5 Steel I 

c/c = Center to center 

1 inch = 2.54 cm 

1 psi = 0.006 895 MPa 

According to table 7, specimens PG-1 and PG-2 and slabs number 1, 4, and 5 had crack 

formation at the joints. In these cases, dowels provided maximum load transfer across the joints. 

This was the scenario expected to occur in the field. 

In slab number 3, a crack occurred at the loaded zone only, away from the sawcut junction of 

two slabs. Under field conditions, such joint formation would not contribute to effective load 

transfer. At most, it would be expected that only a very small portion of the applied load would 

be transferred across this crack. Joint formation at unintended locations may facilitate concrete 

expansion or contraction due to field thermal variations. In slab number 2, cracks occurred at 

both joint and load zone locations. 
22 

The reason for cracks occurring away from mid-joint and under the loading zone could possibly 

be attributed to the uneven base surface under the loaded side of the slab. Because the slabs were 

not cast directly on the aggregates as in the field construction method, when the load was applied, 

the uneven surface including possible gradients could cause enough stress concentration at the 

dowel edge to lead to concrete cracking prior to load transfer. 

PRELIMINARY TESTS 

Preliminary static tests were conducted on two slabs consisting of one 3.8-cm (1.5-inch)-

diameter FRP dowel at 30.48 cm (12 inches) center to center (c/c). LTEs obtained from these 

static tests were both greater than 90 percent, i.e., much higher than 60 percent of LTE as 

recommended by ACPA (corresponding to 75 percent of joint effectiveness, E).(11) 

JOINT DEFLECTIONS AND JOINT LTE 

Deflections of dowel-connected slabs were measured using LVDTs positioned at both loaded 

and unloaded sides of joints. LTE and RDs were then calculated from measured deflections. 

Joint RD 

Joint RD of Group 1 

Slab number 1 consisted of two 2.54-cm (1.0-inch)-diameter FRP dowels with spacing of 

15.24 cm (6 inches) (refer to figure 8, figure 14, and table 7). Static tests were conducted 

according to table 8. RD versus applied load is shown in figure 21. 

Table 8. Static load applied for specimen 1. 

Specimen Number Load Range 

1 0 to 55.603 kN (0 to 12.5 kips) 

Note: 55.603 kN (12.5 kips) was applied corresponding to HS25 load. 

After static testing, fatigue tests were conducted up to 5 million cycles (table 9). Figure 21, 

figure 22, and figure 23 show the RDs obtained from tests. It should be noted that 83.404 kN 

(18.75 kips) (1.5 times HS25 loading) was applied to the joint after 1 million cycles. 

Table 9. Load applied for fatigue tests on slab number 1. 

Slab 

Number 

Wave 

Shape 

Frequency 

(Hz) 

0 to 1 Million 

Cycles 

1 to 5 Million 

Cycles 

1 Sine 4.0 2–12.5 kips 2–18.75 kips 

Note: 55.603 kN (12.5 kips) was applied corresponding to HS25 load, and 83.404 kN (18.75 kips) 

corresponds to 1.5 times HS25 load. 

1 kip = 4.448 kN 
23 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00000 0.00050 0.00100 0.00200 0.00250

Relative Deflection (inches)

Point Corresponding to 

HS25 loading

Load (kips)

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 21. Chart. Joint RD for slab number 1 under static test. 

0.00000

0.00050

0.00100

0.00150

0.00200

0.00250

0.00300

0.00350

Relative Deflection (inches)

12.5 kips 0.00227 0.00330

static 1 M

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 22. Graph. RDs under HS25 loading for slab number 1 at joint width of 

0.635 mm (0.25 inch) (static and 1 million cycles). 
24 

0.00000

0.01000

0.02000

0.03000

0.04000

0.05000

0.06000

0.07000

0.08000

0.09000

Relative Deflection (inches)

12.5 kips 0.01282 0.0479 0.0803

18.75 kips 0.01447 0.0516 0.0841

2 M 4M 5 M

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 23. Graph. RDs for slab number 1 under fatigue tests (joint width increased from 

0.635 cm (0.25 inch) to 1.016 mm (0.4 inch) from 2 to 5 million cycles). 

In figure 23, the 55.603-kN (12.5-kips) load corresponds to HS25 loading and was applied up to 

1 million cycles; 83.404 kN (18.75 kips) corresponds to 1.5 times HS25 loading and was applied 

for fatigue tests after 1 million cycles and up to 5 million cycles. Also, joint width increased 

from 0.635 mm (0.25 inch) to 10.16 mm (0.4 inch) during bin and slab repositioning. Thus, the 

RDs after 1 million cycles due to increased joint width were much greater than those from static 

and 1 million cycle tests (0.3256 mm (0.01282 inch) at 2 million cycles versus 0.0838 mm 

(0.0033 inch) at 1 million cycles. 

Slab number 2 consisted of two 2.54-cm (1-inch)-diameter steel dowels with 15.24-cm (6-inch) 

spacing. A static test was conducted on this slab with a load range of 0 to 55.603 kN (0 to 

12.5 kips), and crack formation was noticed at the dowel edge under the loading plate. Load 

versus RD results are shown in figure 24. After static testing, fatigue tests were conducted 

according to table 10. Because cracks occurred at locations away from the joint, fatigue cycles 

up to 2 million were applied. Figure 25 shows RDs under fatigue tests. It should be noted that 

when cracks occur away from mid-joints, only a small portion of the load would be transferred 

across the joint. 
25 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00000 0.00050 0.00100 0.00150 0.00200 0.00250 0.00300

Relative Deflection (inches)

Load (kips)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 24. Chart. Joint RD for slab number 2 under static test. 

Table 10. Load applied for fatigue tests on slab number 2. 

Slab Number Frequency (Hz) 0–1 Million Cycles > 1–2 Million Cycles 

2 4.0 2–12.5 kips 2–18.75 kips 

Note: 55.603 kN (12.5 kips) was applied corresponding to HS25 load, and 83.404 kN (18.75 kips) 

corresponded to 1.5 times HS25 load. 

1 kip = 4.448 kN 
26 

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

0.0035

0.0040

0.0045

Rela tive D eflectio n

12.5 kips 0.0026 0.0018 0.0040 

18.75 kips 0.0040 

static 1 M 2 M

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 25. Graph. RDs for specimen 2 (0 to 2 million cycles). 

Slab number 3 consisted of two 3.81-cm (1.5-inch)-diameter FRP dowels with 15.24-cm 

(6-inch) spacing. Static deflections were measured for a load range from 0 to 55.603 kN 

(0 to 12.5 kips), and the details are shown in figure 26. Crack locations were away from the midjoint; hence, fatigue tests were conducted up to only 1.25 million cycles (refer to table 11). Table 

11 details the load applied for fatigue tests on slab number 3. Figure 27 shows the RDs under 

fatigue tests. Deviations observed in RD values from slab number 3 were due to crack formation 

under the loading plate at the dowel edge. 
27 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Relative Deflection (inches)

Load (kips)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 26. Chart. Joint RD for specimen 3 under static test. 

Table 11. Load applied for fatigue tests on slab number 3. 

1 kip = 4.448 kN 

0.00000

0.00050

0.00100

0.00150

0.00200

0.00250

0.00300

0.00350

0.00400

0.00450

Relative Deflection (inches)

12.5 kips 0.00400 0.00160

static 1 and 1/4 M

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 27. Graph. RDs for specimen 3 (0 to 1.25 million cycles). 

Slab Number Frequency (Hz) 0–1.25 Million Cycles 

3 4.0 2 to 12.5 kips 
28 

Joint RD of Group 2 

Slab number 4 consisted of one 3.81-cm (1.5-inch)-diameter FRP dowel representing 30.48-cm 

(12-inch) spacing in actual pavement. The static test was conducted in the range from 0 to 

48.930 kN (0 to 11 kips). Load versus RD results are shown in figure 28. After the static test, 

fatigue tests were conducted as per table 12 up to 5 million cycles. Figure 29 and figure 30 show 

pavement deflections and RDs under fatigue testing. 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Relative Deflection (inches)

Load (kips)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 28. Chart. Joint RD for specimen 4 under static test. 

Table 12. Load applied for fatigue tests on slab number 4. 

1 kip = 4.448 kN 

Slab Number Frequency (Hz) 0 to 5 Million Cycles 

4 4.0 2 to 11.0 kips 
29 

0.0

50.0

100.0

150.0

200.0

250.0

300.0

Deflection (x0.001 inches)

Loaded Side 280.0 52.0 52.0 51.0 37.0 39.0

Unloaded Side 251.0 29.0 27.0 22.5 18.0 22.0

static 1 M 2 M 3 M 4 M 5 M

1 inch = 2.54 cm 

Figure 29. Graph. Pavement deflections under fatigue test for slab number 4 

(0 to 5 million cycles, FRP dowel at 30.48 cm (12 inches) c/c). 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

Relative Deflection (inches)

11.0 kips 0.029 0.0248 0.019 0.017

static 2 M 4 M 5 M

1 kip = 4.448 kN 

Figure 30. Graph. RDs under fatigue test for specimen 4 (0 to 5 million cycles). 

Slab number 4 was the first slab tested in the laboratory. Base materials were compacted before 

starting the test, but, during laboratory fatigue cycles testing, base materials under both sides of the 

slabs became more compact and the deflections reduced (figure 29). Similar trends were observed 

under increased fatigue cycles in figure 30. The modulus of subgrade reaction k increased from 

11.072 to 22.144 kg/cm3

 (400 to 800 pci) after 5 million fatigue cycles. 

Slab number 5 consisted of one 3.81-cm (1.5-inch)-diameter steel dowel representing 30.48-cm 

(12-inch) spacing in the pavement. The static test was conducted in the range from 0 to 

48.930 kN (0 to 11.0 kips). Fatigue tests were conducted as per table 13. Figure 31 shows the 
30 

load versus RD. After static testing, fatigue tests were conducted up to 5 million cycles. Figure 

32 shows RDs for slab number 5 under fatigue tests. 

Table 13. Load applied for fatigue tests on slab number 5. 

Slab Number Frequency (Hz) 0 to 5 Million Cycles 

5 4.0 2 to 11.0 kips 

1 kip = 4.448 kN 

0

0.002

0.004

0.006

0.008

0.01

0.012

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Load (k ips)

Series1

Point Corresponding to HS25 

loading 

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 31. Chart. Joint RD for specimen 5 under static test. 

0.0102

0.0104

0.0106

0.0108

0.011

0.0112

Relative Deflection (inches) 11.0 kips 0.0105 0.011

static 2 M

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 32. Graph. RDs under fatigue test for specimen 5 (0 to 5 million cycles). 

Analysis of RD 

Analysis for Specimen Group 1 as per Table 6 (15.24-cm (6-inch) Spacing): 

For slabs number 1 through 3, static and fatigue test results are summarized in table 14 and 

table 15, respectively, and their behavior is discussed in following the tables. Relative Deflection (inches) 
31 

Table 14. RD of group 1 from static tests. 

Slab Number Parameters Static RD (inch) 

1 FRP dowel, 1.0 inch at 6 inches c/c 0.00227 

2 Steel dowel, 1.0 inch at 6 inches c/c 0.00260 

3 FRP dowel, 1.5 inches at 6 inches c/c 0.00400 

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Table 15. RD of group 1 from fatigue tests. 

Slab Number 

Relative Deflection (inch) 

1 M 2 M 4 M 5 M 

Proper Crack at 

Mid-joint 

1 

0.0033 

(Joint width 

= 0.25 inch) 

0.0128*† 0.0479*† 0.0803*† Yes 

2 0.0018 0.0040† — — No 

3 0.0001 — — — No 

* Joint width increased to 1.016 cm (0.4 inch).

† An overload factor of 1.5 was used so that 1.5 times HS25 load was applied for specimens 1 and 2 during 

fatigue tests started after 1 million cycles. 

— No loading at corresponding cycles. 

1 inch = 2.54 cm 

The following results were found: 

• The larger RD (0.00660 cm (0.00260 inch)) in slab number 2 with steel dowels compared to 

that of slab number 1 with FRP dowel (0.00577 cm (0.00227 inch)) can be attributed to the 

cracking pattern in slab number 2 where joint crack occurred at a place other than the mid-joint. 

• Slab number 3 had a much larger RD possibly because the crack formation was close to the 

edge of the dowel under the steel plate rather than at mid-joint. Therefore, the load 

transferred by the dowel was less, including a higher RD. 

• When a crack occurred at a joint location where it was expected to occur, the RD data from 

the tests seemed to be more consistent; for example, the RD for slab number 1 increased 

from 0.00584 to 0.0204 cm (0.0023 to 0.0803 inch). 

• Experimental results on RD were sensitive to supporting base stiffness (k). Therefore, base 

property should be considered before and after each fatigue test. 

Analysis for Specimen Group 2 (30.48-cm (12-inch) Spacing): 

Test results are summarized in table 16 and table 17. 
32 

Table 16. RD of group 2 from static tests. 

Slab Static RD (inch) 

Proper Crack at 

Mid-joint 

Number 4 (FRP dowel, 3.81 cm 

(1.5 inch) at 30.48 cm (12 inches) c/c) 0.029 Yes

Number 5 (steel dowel, 3.81 cm 

(1.5 inch) at 30.48 cm (12 inches) c/c) 0.011 Yes

1 inch = 2.54 cm 

Table 17. RD of group 2 from fatigue tests. 

Slab Number Relative Deflection (inch) 

2 M 4 M 5M 

4 0.025 0.019 0.017 

5 0.011 — — 

— No loading at corresponding cycles. 

The following was noted: 

• Both slabs number 4 and 5 had proper crack occurrence at the joint. 

• In static tests (table 17), slab number 4 (3.81-cm (1.5-inch)-diameter FRP dowel) had a larger 

difference in deflection between loaded and unloaded sides of the pavement (RD) than slab 

number 5 (3.81-cm (1.5-inch)-diameter steel dowel). 

• The RD for both slabs reduced with progression of fatigue load from 0 to 5 million cycles. 

This was partly attributed to compaction/settlement of aggregate base underneath the 

pavement slabs with increasing fatigue cycles. 

• RD decreased more in slabs with FRP dowels than with steel dowels, which can be partly 

attributed to simulation in stiffness between FRP and concrete. Benefits of these reductions 

may be more evident with freeze-thaw variations. 

• Experimental results on RD were sensitive to supporting base stiffness (k). It was found that 

the base property (modulus of subgrade reaction, k) value changed from 11.072 to 

22.144 kg/cm3

 (400 to 800 pci) after 5 million fatigue cycles. 

Joint LTE 

Joint LTE (figure 33 through figure 38) was calculated from the results of static and fatigue tests 

by using equation 1 as follows:(1)

×= 100%

L

U

d

d

LTE

 (1) 
33 

Where: 

dU = Deflection at unloaded side. 

L d = Deflection at loaded side. 

ACPA gives joint effectiveness, E, to measure the performance of joints (equation 2):(11) 

100%

2

×

+ =

UL

U

dd

d

E

 (2) 

Where: 

dU = Deflection at unloaded side. 

L d = Deflection at loaded side. 

ACPA recommends that a pavement joint be considered adequate if the effectiveness is 

75 percent or greater. However, LTE and E are related by equation 3:(3)

1 100%

 - 2

2 LTE ⎟×

⎠

⎞ ⎜

⎝

⎛ −= E (3) 

According to equation 3, an LTE of 60 percent corresponds to an E of 75 percent. When the value of 

LTE is between 70 and 100 percent, the joint provides sufficient load transfer for heavy loads. 

LTE of Group 1 

Slab Number 1: 

96.50

97.00

97.50

98.00

98.50

99.00

99.50

100.00

100.50

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

Applied Load (kips)

Load Transfer Efficiency (%)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

Figure 33. Chart. Joint LTE for slab number 1. 
34 

92.00

93.00

94.00

95.00

96.00

97.00

98.00

LTE (%)

12.5 kips 97.09 93.79

static 1 M

1 kip = 4.448 kN 

Figure 34. Graph. LTE corresponding to HS25 loading for slab number 1 (2.54-cm 

(1.0-inch) diameter at 15.24 cm (6 inches) c/c), static and 1 million cycles. 

In figure 35, a load of 55.603 kN (12.5 kips) corresponding to HS25 loading was applied for the 

static test and 1 million cycles; 83.404 kN (18.75 kips) corresponding to 1.5 times HS25 loading 

was applied for fatigue tests from 2 to 5 million cycles. Also, joint width was intentionally 

separated from to 0.635 to 1.016 cm (0.25 to 0.4 inch). 

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

LTE (%)

12.5 89.71 83.0248307 68.87589344 71.1566092

18.75 89.19 82.07792208 68.24615385 70.75799722

2 M3 M4 M5 M

Figure 35. Graph. LTE for slab number 1 under fatigue tests ( > 1 million cycles and joint 

width increased from 0.635 to 1.016 cm (0.25 to 0.4 inch)). 
35 

To find the condition of the interface between the FRP dowel and concrete, slab number 1 was 

separated by cutting the FRP dowel after 5 million cycles of HS25 and higher loading. The 

dowel-concrete interface was found to be in good shape with no visible microcracks (figure 36). 

GOOD CONDITION 

AFTER 5 MILLION 

CYCLES OF HS25 AND 

HIGHER LOADING 

Figure 36. Photo. Dowel-concrete interface condition in slab number 1 

after 5 million load cycles. 

Slab Number 2: 

0.00

20.00

40.00

60.00

80.00

100.00

120.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

Load (kips)

LTE (%)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

Figure 37. Chart. Joint LTE for slab number 2. 
36 

89.00

90.00

91.00

92.00

93.00

94.00

95.00

96.00

Load (kips)

LTE 94.13 91.67 94.87 94.74 95.52

static 1/4 M 1/2 M 3/4 M 1 M

1 kip = 4.448 kN 

Figure 38. Graph. LTE under fatigue tests (HS25 loading) for slab number 2 

(0 to 1 million cycles). 

In figure 39, a load of 55.603 kN (12.5 kips) corresponding to HS25 loading was applied for the 

static test and up to 1 million cycles; 83.404 kN (18.75 kips) corresponding to 1.5 times HS25 

loading was applied for fatigue tests after 1 million cycles. 

LTE Under Fatigue Load

92.00

92.50

93.00

93.50

94.00

94.50

95.00

95.50

96.00

LTE (%)

12.5 kips 94.13 95.52 93.33

18.75 kips 93.94

static 1 M 2 M

1 kip = 4.448 kN 

Figure 39. Graph. LTE under fatigue test for slab number 2 

(1 to 2 million cycles). 
37 

Slab Number 3: 

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

Load (kips)

LTE (%)

Point Corresponding to 

HS25 loading 

1 kip = 4.448 kN 

Figure 40. Chart. Joint LTE for slab number 3. 

90.00

92.00

94.00

96.00

98.00

100.00

102.00

LTE (%) 12.5 kips 93.33 99.69 95.21

static 1 M 1 and 1/4 M

1 kip = 4.448 kN 

Figure 41. Graph. LTE under fatigue test for slab number 3 (0 to 1.25 million cycles). 

The crack that occurred in slab number 3 was away from mid-joint; hence, these results 

(figure 40 and figure 41) did not have much significance. 

Joint LTE of Group 2 

Slab Number 4: 

During static testing, slab number 4 was subjected to loading up to 48.930 kN (11 kips) 

corresponding to HS25 loading, and the response is shown in figure 42. 
38 

50.00

55.00

60.00

65.00

70.00

75.00

80.00

85.00

90.00

95.00

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Load (kips)

LTE (

%

LOW LTE AT LOW LOAD 

DUE TO INITIAL BASE 

SETTLEMENT EFFECTS

POINT 

CORRESPONDING 

TO HS25 LOADING

LTE (%) 

1 kip = 4.448 kN 

Figure 42. Chart. Joint LTE for slab number 4. 

In fatigue tests, slab number 4 provided good LTE—greater than 80.5 percent after 5 million 

fatigue load cycles when the base surface and base material under this slab remained in good 

condition. When base aggregates were not in contact with the slab due to aggregate compaction 

or slight sideways flexing of the aggregate bin, LTE was found to have been decreased to about 

55 percent, which was still around 92.1 percent of the 60 percent LTE which corresponded to the 

ACPA-recommended value on joint effectiveness (E) of 75 percent. Detailed data are shown in 

figure 43. 

0

10

20

30

40

50

60

70

80

90

100

LTE (%) Good base condition 89.6 85.1 80.5

Poor base condition 89.6 50.7 55.26

static 2 M 5 M

LTE (%) 

Figure 43. Graph. LTE under fatigue test for slab number 4 (0 to 5 million cycles). 
39 

From figure 43, LTE of slab number 4 containing FRP dowels remained at about 80 percent with 

good base condition. With poor base condition, LTE reduced from 88 percent to 55 percent 

(92.1 percent of the 60 percent LTE which corresponded to the ACPA-recommended value on 

joint effectiveness (E) of 75 percent). The poor base condition was observed with a concave slabbase surface due to aggregate compaction and base settlement. Also, it should be noted that the 

slabs were not cast directly on top of the aggregates, which led to some aggregate repositioning 

under fatigue loading. The modulus of subgrade reaction k was found changed from 

11.072 to 22.144 kg/cm3

 (400 to 800 pci) after 5 million cycles in poor base condition. 

To find the condition of the interface between the FRP dowel and the concrete, slab number 4 

was separated by cutting the FRP dowels after 5 million cycles of HS25 and higher loading. The 

dowel-concrete interface was found to be in good shape with no visible microcracks (figure 44). 

GOOD 

CONDITION 

AFTER 5 

MILLION 

CYCLES OF 

HS25 AND 

HIGHER 

LOADING 

Figure 44. Photo. Dowel-concrete interface condition in slab number 4 

after 5 million load cycles. 

Slab Number 5: 

LTE of slab number 5 under static and fatigue loads are shown in figure 45 and figure 46, 

respectively. 
40 

50.00

55.00

60.00

65.00

70.00

75.00

80.00

85.00

90.00

95.00

5.5 6.5 7.5 8.5 9.5 10.5 11.5

Load (kips)

LTE (%)

Point corresponding to 

HS25 loading 

1 kip = 4.448 kN 

Figure 45. Chart. Joint LTE for slab number 5. 

89.3

89.4

89.5

89.6

89.7

89.8

89.9

90

90.1

90.2

90.3

LTE (%) 11 kips 89.64 90.21

static 2 M

LTE (%) 

1 kip = 4.448 kN 

Figure 46. Graph. LTE under fatigue test for slab number 5 (0 to 5 million cycles). 

Analysis and Discussion for Joint LTE 

Analysis and Discussion for Slab Group 1 (15.24-cm (6-inch) Spacing): 

Test results are summarized in table 18 and table 19. 
41 

Table 18. LTE of group 1 from static tests. 

Slab Number LTE (percent) 

1 97.79 

2 94.13 

3 93.33 

Table 19. LTE of group 1 during fatigue tests. 

Specimen 

Number 

LTE ( percent) 

1 M 2 M 4 M 5 M 

Proper Crack at 

Mid-joint 

1 

93.79 

(joint width = 

0.25 inch) 

89.71*† 68.88*† 71.57*† Yes 

2 95.52 93.33† — — No 

3 99.69 — — — No 

 * Joint width was increased to 1.016 cm (0.4 inch). 

† An overload factor of 1.5 was used so that 1.5 times HS25 load was applied for specimens 1 and 2 during 

fatigue tests and started from 2 million cycles. 

— No loading at corresponding cycles. 

1 kip = 4.448 kN 

The following can be said: 

• In static tests, all slabs provided good LTE, which was greater than 60 percent of LTE 

(corresponding to 75 percent of joint effectiveness, E).(9) Slab number 1 (2.54-cm (1.0-inch)-

diameter FRP dowel with 15.24-cm (6-inch) spacing) with proper crack formation at the midjoint had a greater than 90 percent LTE, which was slightly larger than the LTE for slab 

number 2 (2.54-cm (1.0-inch)-diameter steel dowel with 15.24-cm (6-inch) spacing) and slab 

number 3 (3.81-cm (1.5-inch)-diameter FRP dowel with 15.24-cm (6-inch) spacing). Slabs 

number 2 and 3 had crack formation away from the mid-joint (table 7). In slab number 1, the 

dowel worked as per design to transfer maximum load.(11)

• Even when 1.5 times the design load (HS25 loading) and an influence of increased joint 

width (increased from 0.635 to 1.016 cm (0.25 to 0.4 inch) were considered, the observed 

LTE in slab number 1 was consistent (reduced from 93.79 to 71.57 percent) due to the right 

crack position and still higher than 60 percent of LTE (corresponding to 75 percent of joint 

effectiveness, E).(11)

• Pumping and erosion under the loaded side of the slabs was observed during the tests. This 

could be the main reason that LTE of slab number 1 was reduced. Base settlement was also a 

reason for reduced LTE. Therefore, base property (such as k, modulus of subgrade reaction) 

should be checked before and after each fatigue test. 

Analysis and Discussion for Slab Group 2 (30.48 cm (12-inch) Spacing): 

Tests results are summarized in table 20 and table 21. 
42 

Table 20. LTE of group 2 from static tests under corresponding HS25 load. 

Slab Number LTE (percent) 

4 88.48 

5 89.00 

Table 21. LTE of group 2 from fatigue tests. 

Slab Number 

LTE (percent) 

2 M 4 M 5 M 

4 85.1 — 80.5 

50.70* 47.22 55.26*

5 90.21 — — 

— No loading at corresponding cycles. 

* Results from tests conducted on poor base condition. 

The following can be found: 

• Both slab number 4 and slab number 5 had proper crack occurrence at the joint. 

• In static tests, both slabs had very good LTE, more than 88 percent, which was much greater 

than 60 percent of LTE (corresponding to 75 percent of joint effectiveness, E). Thus, FRP 

dowels performed as well as steel dowels and showed LTE as good as steel dowels in the 

static tests.(11)

• After 2 million HS25 fatigue loading cycles, for the same dowel diameters and spacing, the 

concrete pavement containing FRP dowels provided slightly lower LTE (85.1 percent versus 

90.21 percent) than pavement containing steel dowels (table 21). With poor base condition, 

the LTE of slabs with FRP dowels over steel dowels was 50.71 percent versus 90.21 percent. 

• The LTE of slabs with FRP dowels remained greater than 80 percent after 5 million loading 

cycles. 

Investigations on Pavement Pumping Problem 

Pumping is a common problem occurring in concrete pavements due to the movement of 

material underneath the slab or ejection of material from underneath the slab as a result of water 

pressure. Pumping will cause decreased structural support of the slab, which can lead to linear 

cracking, corner breaks, and faulting. 

Two cases of pumping tests were conducted (figure 47 and figure 48). In case one, base material 

under the loaded side of the slabs was removed for a 60.96-cm (2-ft) range to simulate the 

pumping problem occurring in the field (figure 47). These tests were conducted only on slab 

number 4 (3.81-cm (1.5-inch)-diameter FRP dowel at 30.48 cm (12 inches) c/c) and slab 

number 5 (3.81-cm (1.5-inch)-diameter steel dowel at 30.48 cm (12 inches) c/c) up to 44.482 kN 

(10 kips). Test results are shown in figure 49 and figure 50 and in table 22 and table 23. 
43 

1 inch = 2.54 cm 

Figure 47. Diagram. Case one—60.96-cm (2-ft) base material removal 

under loaded side of slabs. 

1 inch = 2.54 cm 

Figure 48. Diagram. Case two—30.48-cm (1-ft) base material removal 

under both sides of slabs. 
44 

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Load (kips)

Relative Deflection (inches)

FRP (slab 4)

stee (slab 5)

1 kip = 4.448 kN 

1 inch = 2.54 cm 

Figure 49. Chart. RD for pumping tests (case one—60.96-cm (2-ft) base removal). 

50.00

60.00

70.00

80.00

90.00

100.00

110.00

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Load (kips)

LTE(%)

FRP

steel

1 kip = 4.448 kN 

Figure 50. Chart. LTE for pumping tests (case one—60.96-cm (2-ft) base removal). 
45 

Table 22. Evaluation of pumping issue under 44.482 kN (10 kips) loading. 

Test Case Number Dowel Material 

Relative 

Deflection 

(× 10-3 inch) LTE (percent) 

Case one 

(2-ft base removal 

under loaded slab) 

FRP (slab number 4) 21.9 92.42

Steel (slab number 5) 6.4 98.21

Case two 

(1-ft base removal 

under both slabs) 

FRP (slab number 4) — —

Steel (slab number 5) — —

— No loading at corresponding cycles. 1 inch = 2.54 cm 

Table 23. Evaluation of pumping issue under 13.345 kN (3 kips) loading. 

Test Case Number Dowel Material 

Relative 

Deflection 

(× 10-3 inch) 

LTE 

(percent) 

Case one 

(2-ft base removal 

under loaded slab) 

FRP (slab number 4) 13.5 88.00 

Steel (slab number 5) 6.4 97.15 

Case two 

(1-ft base removal 

under both slabs) 

FRP (slab number 4) 16.5 91.95 

Steel (slab number 5) 1.1 99.09 

1 inch = 2.54 cm 

In case two, base material under each side of the slabs was removed for a 30.48-cm (1-ft) range 

(figure 50). When loading exceeded 13.345 kN (3 kips), the joint opening closed, and the two 

faces of the joint bore against each other. Hence, tests were conducted only on slabs number 4 

and 5 up to 13.345 kN (3 kips) in case two. Test results are shown in figure 51 and figure 52. 
46 

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

Relative Deflection (inches)

Relative Deflection 0.0165 0.0011

FRP steel

1 inch = 2.54 cm 

Figure 51. Graph. RD for pumping tests under 13.345 kN (3 kips) loading 

(case two—30.48-cm (1-ft) base removal under both slabs). 

88.00

90.00

92.00

94.00

96.00

98.00

100.00

LTE (%)

LTE 91.95 99.09

FRP steel

Figure 52. Graph. LTE for pumping tests under 13.345 kN (3 kips) loading 

(case two—30.48-cm (1-ft) base removal under both slabs). 

Test results from cases one and two are compared and summarized in table 22 and table 23. 

The following can be found: 

• LTEs were observed in cases investigated for the simulated pavement pumping problem with 

supporting base removal up to a certain length near the joint (figure 47 and figure 48). LTEs 

were not less than the LTEs obtained from intact base condition (table 20). However, under 
47 

fatigue load cycles, LTE was expected to reduce significantly for specimens without support 

near the joint. 

• LTE obtained in case two (30.48-cm (1-ft) base material removal under both sides of slabs) 

was greater than 90 percent at 13.345 kN (3 kips) loading, and, after loading exceeded 

13.345 kN (3 kips), two joint faces would bear against each other. Thus, case two (30.48-cm 

(1-ft) base removal under both slabs) with unsupported slab areas on both sides of the slab 

was more detrimental than case one (60.96-cm (2-ft) base removal under the loaded slab). 

Strains on Dowels 

Most of the strain gauges installed on dowels survived before fatigue tests. However, some of 

them did not function properly after fatigue tests. Strain readings shown in this section are only 

from slab number 1 (2.54-cm (1.0-inch) diameter at 15.24-cm (6-inch) spacing c/c) (figure 53) 

and slab number 4 (3.81-cm (1.5-inch) diameter at 30.48-cm (12-inch) spacing c/c) (figure 54). 

-600.00

-500.00

-400.00

-300.00

-200.00

-100.00

0.00

Strain (x10 -6) Loaded -411.62 -127.55 -179.66 -201.00 -235.00 

Unloaded -513.04 -264.39 -210.62 -237.00 -230.00 

static 1/4 M 1/2 M 3/4 M 1 M

Figure 53. Graph. Strain gauge reading in slab 1 (2.54-cm (1.0-inch) diameter at 15.24-cm 

(6-inch) spacing c/c) from static test to 1 million cycles under HS25 loading). 
48 

0

2

4

6

8

10

12

0 50 100 150 200 250 300 350 400

Strain (microstrain)

Load (kips)

GAUGE ON 

LOADED SIDE 

1 kip = 4.448 kN 

Figure 54. Chart. Strain gauge reading in slab number 4 (3.81-cm (1.5-inch) diameter at 

30.48-cm (12-inch) spacing c/c) from static test under HS25 loading. 

Strain values at the unloaded side of dowels during static tests from slabs number 1 and 4 were 

513.04 and 376.43 microstrains, respectively. Both values were less than those from analytical 

evaluation (ranges from 1,000 to 1,200 microstrains), but strain values were typically not used 

for LTE calculation. 
49 

CHAPTER 5. FIELD APPLICATIONS AND TEST RESULTS 

INTRODUCTION 

Experimental tests and results discussed in chapter 4 show that FRP dowels can provide 

sufficient LTE under heavy traffic load rating (HS25 load and 1.5 times HS25). The purpose of 

the field test program was to investigate FRP dowel performance and FRP-concrete interaction 

in full-scale highway pavement slabs under realistic loading and field exposure conditions. 

Field application and tests were done in collaboration with the WVDOT DOH. FRP dowels were 

used for new pavement construction and rehabilitation of damaged pavement sections. FRP 

dowel joints were used for new highway pavement construction on Route 219 and Route 33 East 

in Elkins, WV, from September to November 2001. Field tests were conducted in July 2002 and 

June 2003. FRP dowels were used for pavement rehabilitation at the junction of Routes 119 and 

857, University Avenue, Morgantown, WV, during October 2002. 

FRP DOWELS FOR NEW HIGHWAY PAVEMENT CONSTRUCTION 

FRP dowels were used during the construction of new highway Route 219 and Route 33 East in 

Elkins, WV. The installation and field test setup are discussed in this section. Field test results 

are also analyzed and discussed. 

Field Locations 

Two locations separated by about 6.4 km (4 mi) were selected for field installations in corridor H 

highway at Route 219 and Route 33 in Elkins, WV. Location 1 (figure 55 and 

figure 56) was westbound, and location 2 (figure 57 and figure 58) was eastbound. 

Figure 55. Photo. Dowel installation at location 1 of corridor H, Route 250, Elkins, WV.
50 

Figure 56. Diagram. FRP dowel positions at location 1 of corridor H, Route 250, 

Elkins, WV.

Only dowels with shading in figure 56 were instrumented. 

Figure 57. Photo. FRP dowel bars at location 2 of corridor H, Route 219, Elkins, WV.
51 

Side pipes carried wires from instrumented dowels to the outside of the shoulder region 

(figure 57). 

1.5 inch 

diameter 

1.0 inch 

diameter 

1 inch = 2.54 cm 

Figure 58. Diagram. FRP dowel positions at location 2 of corridor H, Route 219, 

Elkins, WV. 

Only dowels with shading in figure 58 were instrumented. 

Field Installation 

FRP dowels were instrumented with strain gauges (figure 59) to monitor strains in dowel bars 

installed in the field. Embeddable concrete strain gauges (figure 60) were also installed to 

monitor strains in the pavement. 

Dowel bars with 2.54-cm (1.0-inch) diameter (figure 60) and 3.81-cm (1.5-inch) diameter 

(figure 61) were supported by plastic baskets at design spacings of 30.48, 22.86, 20.32, or 

15.24 cm (12, 9, 8, or 6 inches) (figure 56 and figure 58). Plastic baskets were anchored by either 

steel stakes (figure 60) or plastic stakes (figure 61). 

Construction was carried out as shown in figure 62 and figure 63. Wires from instrumented 

dowels were carried through hollow polyvinyl chloride pipes to the outside of the pavement 

shoulder (figure 63). 
52 

Strain gauges 

Figure 59. Photo. FRP dowel bars bonded with strain gauges at loaded and unloaded sides. 

Embeddable 

strain gauge 

Steel 

stake 

Figure 60. Photo. Embeddable concrete strain gauge with dowels. 
53 

Expansion Cap Dowel Basket 

Plastic stake 

to hold basket 

Figure 61. Photo. FRP dowels in dowel basket. 

Figure 62. Photo. Paving operation in progress.
54 

PVC pipe to carry away 

wires from dowels 

Figure 63. Photo. FRP dowel bars being covered by concrete. 

FIELD TESTS 

Figure 64 shows a standard AASHTO Type 3 truck load that was used to carry out field 

evaluations before and after opening the pavement to the traffic.(12) Strain gauge readings were 

recorded prior to and after pavement construction (November 2001) and also during the field 

testing conducted in July 2002 and June 2003. The automatic data acquisition system was used to 

collect test data. 

Field Test Before Opening Highway to Traffic in July 2002 

A field test was completed before opening the pavement to traffic in July 2002. Static and 

dynamic tests including brake tests were conducted during this test. Parameters used for field 

testing are provided in table 24. 
55 

Table 24. Parameters of the field test at location 2, July 2002. 

Dowel material FRP 

Dowel diameter 3.81 cm, 2.54 cm (1.5 inches, 1.0 inch) 

fc′ 24.132 MPa (3,500 psi) 

Dowel spacing 

30.48 cm (12 inches), 3.81-cm (1.5-inch) diameter 

22.86 cm (9 inches), 3.81-cm (1.5-inch) diameter 

20.32 cm (8 inches), 2.54-cm (1.0-inch) diameter 

15.24 cm (6 inches), 2.54-cm (1.0-inch) diameter 

Type of loading 

Truck type: AASHTO Type 3 (regular two-axle truck) 

Gross weight: 22.680 metric tons (50,000 lb) (AASHTO) 

Gross weight: 24.385 metric tons (53,760 lb) (actual) 

Front axle: 7.257 metric tons (16,000 lb) (AASHTO) 

Front axle: 7.158 metric tons (15,780 lb) (actual) 

Rear axle: 15.422 metric tons (34,000 lb) (AASHTO) 

Rear axle: 17.227 metric tons (37,980 lb) (actual) 

Wheel load: 3.856 metric tons (8,500 lb) (AASHTO) 

Wheel load: 4.307 metric tons (9,495 lb) (actual) 

Types of tests 

Static 

Dynamic: 16.1, 32.2, 48.3, 80.5 km/h (10, 20, 30, 50 mi/h) 

Brake test: speed of 80.5 km/h (50 mi/h) 

Instrumentations 

Strain gauges 

Dial gauges for measuring pavement deflection 

Data acquisition system 

Measurements Strain gauge reading 

Pavement deflection 

Computation 

Strain versus loading history 

LTE 

RD 

Test Setup 

A WVDOT truck with calibrated loads was used in the tests (table 24). The truck was positioned 

at required locations to apply load on instrumented dowels (figure 58 and figure 64). 

The loading test for a joint consisted of guiding a truck slowly toward the designated joint from 

about a 15.24-m (50-ft) distance. The unloading test for a joint consisted of guiding a truck 

initially placed on the pavement joint to leave the joint slowly. 

All strain gauges on FRP dowels and embeddable concrete gauges were connected to data 

acquisition (figure 65). Dial gauges were fixed on a long, adjustable stand system. Dial gauges 

were positioned according to the spacing of dowels (figure 55 through figure 58) at the pavement 

joint considered for testing. The span of the dial gauge stand system was long enough to support 

it on adjacent pavement to avoid the influence of support deflections. Strains in dowels and 

deflection of pavement on loaded and unloaded sides of the joint were recorded. 
56 

Figure 64. Photo. Dial gauges for measuring pavement deflection under truck loading.

Figure 65. Photo. Data acquisition system used for field tests.
57 

Test Results and Analysis 

Strain Data from Field Static Tests: 

About 60 percent of strain gauges installed on FRP dowels were found to be working properly 

after field installation and pavement construction. It was also found that some strain data 

recorded by the data acquisition system contained significant noise. Field test results of four 

cases of FRP dowels were analyzed. 

Joints with different diameters and spacing have been described in this section. Data for brake 

tests and dynamic tests from different vehicle speeds are included. 

Performance of FRP dowels with different diameters and/or spacings chosen from the field 

installation (table 25) are discussed in the next several sections with respect to the following: 

• FRP 3.81-cm (1.5-inch) diameter at 22.86 cm (9 inches) c/c (dowel A1, figure 66 and 

figure 67). 

• FRP 3.81-cm (1.5-inch) diameter at 30.48 cm (12 inches) c/c (dowel A2, figure 68 and 

figure 69). 

• FRP 2.54-cm (1.0-inch) diameter at 15.24 cm (6 inches) c/c (dowel C5, figure 70 and 

figure 71). 

• FRP 2.54-cm (1.0-inch) diameter at 20.32 cm (8 inches) c/c (dowel C6, figure 72 and 

figure 73). 

Table 25. Joint details used for analysis. 

Dowel 

Number 

Diameter, 

cm (inches) 

Spacing, 

cm (inches) 

A1 3.81 (1.5) 22.86 (9)

A2 3.81 (1.5) 30.48 (12)

C5 2.54 (1.0) 15.24 (6)

C6 2.54 (1.0) 20.32 (8)
58 

Wheel load 

Figure 66. Diagram. Dowel A1 (3.81-cm (1.5-inch) diameter, 22.86-cm (9-inch) spacing); 

refer to figure 58. 

-15

-10

-5

0

5

10

15

0 5 10 15 20 25 30

Loading Time (s)

Microstrain

Loading

Unloading

Figure 67. Chart. Strains in dowel during loading and unloading cases for gauge A1-LT 

(3.81-cm (1.5-inch) diameter, 22.86-cm (9-inch) spacing).
59 

Wheel load 

Figure 68. Diagram. Dowel A2 (3.81-cm (1.5 inch) diameter, 30.48-cm (12-inch) spacing); 

refer to figure 58. 

-40

-30

-20

-10

0

10

20

30

40

0 5 10 15 20 25 30

Loading Time (s)

Microstrain

Loading

Unloading

Figure 69. Chart. Strains in dowel during loading and unloading cases for gauge A2-LT 

(3.81-cm (1.5-inch) diameter, 30.48-cm (12-inch) spacing); refer to figure 58.
60 

Figure 70. Diagram. Dowel C5 (2.54-cm (1.0-inch) diameter, 15.24-cm (6-inch) spacing); 

refer to figure 58.

-4

-3

-2

-1

0

1

2

3

4

0 10 20 30 40 50 60 70

Loading Time (s)

Microstrain

Loding

Unloading

Figure 71. Chart. Strains in dowel during loading case for gauge C5-U1 (2.54-cm (1.0-inch) 

diameter, 15.24-cm (6-inch) spacing); refer to figure 58. 
61 

Wheel load 

Figure 72. Diagram. Dowel C6 (2.54-cm (1.0-inch) diameter, 20.32-cm (8-inch) spacing); 

refer to figure 58. 

-10

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16

Loading Time (s)

Microstrain

Figure 73. Chart. Strains on dowel during loading case for gauge C6-U1 (2.54-cm (1.0-inch) 

diameter, 20.32-cm (8-inch) spacing); refer to figure 58.
62 

Strain Data from Dynamic Tests: 

Dynamic tests were conducted in this field evaluation. The loaded WVDOT truck with speeds of 

16.09, 32.19, 48.28, and 80.47 km/h (10, 20, 30, and 50 mi/h) crossed the selected joint 

containing instrumented FRP dowels. Data were collected through the automatic data acquisition 

system during truck speeding and braking of the speeding truck at 48.28 km/h (30 mi/h) close to 

the joint. Test results are shown in figure 74 and figure 75. 

-4

-2

0

2

4

6

8

10

12

14

16

Time (s)

Strain (Microstrain)

10 mph

30 mph

50

brake test

1 mi/h = 1.61 km/h 

Figure 74. Chart. Strain from gauge A1-LT (3.81-cm (1.5-inch)-diameter FRP dowel at 

22.86-cm (9-inch) spacing) from dynamic tests. 
63 

-40

-20

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14 16 18

Time (s)

Strain (Microstrain)

10 mph

30 mph

50 mph

brake test

Figure 75. Chart. Strain from gauge A2-LT (3.81-cm (1.5-inch)-diameter FRP dowel at 

30.48-cm (12-inch) spacing) from dynamic tests. 

Dynamic test results recorded contained significant noise, and hence, data are not further 

discussed. 

Analysis of test result: 

Figure 66 through figure 73 show changes in dowel strain near pavement joints during truck loading 

and unloading. Stresses at points on individual dowels can also be obtained according to the stressstrain relationship under bending. Table 26 contains a summary of the above strain values. 

Table 26. Summary of FRP dowel strain during loading and unloading. 

Dowel 

No. 

Dowel 

Diameter 

(inches) 

Dowel 

Spacing 

(inches) 

Maximum Strain 

(microstrain) 

Loading Unloading 

A1 1.5 9 9 12 

A2 1.5 12 31 29 

C5 1.0 6 3 3 

C6 1.0 8 60 N/A 

1 inch = 2.54 cm 
64 

The following can be found from table 26: 

• Change in strain value for the same dowel during loading and unloading cases was almost the 

same. 

• Effect of dowel spacing: 

o For FRP dowels (A1 and A2) with 3.81-cm (1.5-inch) diameters, dowel A2 with larger 

spacing (30.48 cm (12 inches)) had a greater strain change (31 microstrain) than dowel 

A1 with 22.86-cm (9-inch) spacing (change of 9 microstrain). Similarly, for FRP dowels 

C5 and C6 with the same 2.54-cm (1.0-inch) diameter, the dowel C5 with smaller spacing 

(15.24 cm (6 inches)) showed a small strain change (3 microstrain) when compared with 

C6 with 20.32-cm (8-inch) dowel spacing (60 microstrain). 

o Decreasing the spacing by 25 percent (from 30.48 to 22.86 cm (12 to 9 inches) and from 

20.32 to 15.24 cm (8 to 6 inches) resulted in more dowels sharing the load within the 

radius of relative stiffness (lr, chapter 6), leading to 30 percent or higher strain reductions 

in dowels. 

o For FRP dowels with 2.54-cm (1.0-inch) diameter (C5 and C6), a spacing increase from 

15.24 to 20.32 cm (6 to 8 inches) had a greater influence on strain value change (3 versus 

60 microstrain) than the increase of spacing from 22.86 to 30.48 cm (9 to 12 inches) in 

dowels (A1 and A2) with 3.81-cm (1.5-inch) diameters (9 versus 31 microstrain). 

o Dowels with different diameters and spacings could be compared with each other with 

strain value only. Because FRP dowels acted as a group, spacing and diameter were both 

important factors for the group action. It should also be noted that FRP dowels with 

smaller diameter typically had better mechanical properties per unit area than largerdiameter dowels due to shear lag effects (refer to chapter 6). 

Deflection Data: 

The WVDOT truck was guided toward the pavement joint on top of the chosen dowel location so 

that a heavier wheel load, which was located in the rear axles, could be applied. Pavement 

deflections increased when the WVDOT truck slowly approached the joint, but most of the 

deflection changes were less than the detectable range of the dial gauges with a count of 

0.0254 cm (0.001 inch). In the second field test, LVDTs were used instead of dial gauges for 

better precision in deflection detection. 

Field Test after Highway Opened to Traffic, June 2003 

This field test was conducted about 1 year after opening the pavement to traffic. Test parameters 

are listed in table 27. They are similar to those for the first field test, except that the deflection 

measurements were made using LVDTs, and there were no dynamic/brake tests. The main 

purpose of this field test was to investigate deflection behavior and LTE of concrete pavement 

joints with different diameters and spacing of FRP dowel bars. Figure 76 through figure 79 show 

details of the field test setup. 
65 

Table 27. Parameters of the field test, June 2003. 

Dowel material FRP 

Dowel diameter 3.81 and 2.54 cm (1.5 and 1.0 inches) 

fc′ 24.132 MPa (3,500 psi) 

Dowel spacing 30.48, 22.86, 20.32, and 15.24 cm 

(12, 9, 8, and 6 inches) 

Type of loading 

AASHTO Type 3 (regular two-axle truck) 

loaded truck, similar to the one described in 

table 24 

Types of tests Static 

Instrumentations 

Strain gauges 

LVDT for measuring pavement deflection 

Data acquisition system 

Measurements Pavement deflection 

Strain 

Computation LTE 

RD 

It should be noted that the wheel load due to AASHTO HS25 is 9.071 metric tons (20,000 lbs), 

which is about twice the WVDOT truck wheel load used for this test. Under the AASHTO wheel 

load, larger deflections and strains can be expected. 

Figure 76. Photo. WVDOT truck used for field tests.
66 

Figure 77. Photo. WVDOT truck positioned near a joint for the test.

Figure 78. Photo. Two LVDTs measuring pavement deflections across a joint.
67 

Figure 79. Photo. Measuring distance from tire to LVDTs (when loading is away from the 

selected dowel).

Test Results from Field Test 

Four concrete pavement joints with instrumented dowels were tested during the second field test. 

Details of the joints and FRP dowels are shown in table 28. 

Table 28. Pavement joint for deflection analysis. 

Joint Number 

Dowel Bar Diameter, 

cm (inches) 

Dowel Bar Spacing, 

cm (inches) Data Sets Analyzed 

3 3.81 (1.5) 30.48 (12) 2 

2 3.81 (1.5) 22.86 (9) 2 

5 2.54 (1.0) 20.32 (8) 1 

6 2.54 (1.0) 15.24 (6) 1 

Test results are shown in figure 80 through figure 86 and further analyzed in the next section. 
68 

-0.0045

-0.0040

-0.0035

-0.0030

-0.0025

-0.0020

-0.0015

-0.0010

-0.0005

0.0000

0.0005

0.0010

0 5 10 15 20 25 30

Loading Time (s)

Deflection (inches)

side 1

side 2

Fully loaded point:

Deflection (in.): 0.0038 (loaded)

 0.0031 (unloaded)

Relative Deflection (in.): 0.0007

LTE (%): 81.58%

1 inch = 2.54 cm 

Figure 80. Chart. Deflection on pavement joint 3 (with 3.81-cm (1.5-inch)-diameter 

and 30.48-cm (12-inch)-spacing FRP dowels) under loading.

-0.002

-0.001

0

0.001

0.002

0.003

0.004

5 10 15 20 25

Loading Time (s)

Deflection (inches)

Side 1

Side 2

Fully unloaded point:

Deflection (in.): 0.0035 (loaded)

 0.0033 (unloaded)

Relative Deflection (in.): 0.0002

LTE (%): 94.29%

1 inch = 2.54 cm 

Figure 81. Chart. Deflection on pavement joint 2 (with 3.81-cm (1.5-inch)-diameter 

and 22.86-cm (9-inch)-spacing FRP dowels) under unloading.
69 

-0.0060

-0.0050

-0.0040

-0.0030

-0.0020

-0.0010

0.0000

0.0010

0.0020

33 43 53 63 73 83 93 103 113 123

Loading Time (s)

Deflection (inches)

side 1

side 2

Fully loaded point:

Deflection (in.): 0.0056 (loaded)

 0.0053 (unloaded)

Relative Deflection (in.): 0.0003

LTE (%): 94.64%

1 inch = 2.54 cm 

Figure 82. Chart. Deflection on pavement joint 2 (with 3.81-cm (1.5-inch)-diameter 

and 22.86-cm (9-inch)-spacing FRP dowels) under loading.

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

20 30 40 50 60 70

Loading Time (s)

Deflection (inches)

Side 1

Side 2

Fully loaded point

Delfection (in.):0.0020 (loaded)

 0.0019 (unloaded)

Relative Deflection (in.): 0.0001

LTE (%): 95.00%

1 inch = 2.54 cm

Figure 83. Chart. Deflection on pavement joint 5 (with 2.54-cm (1.0-inch)-diameter 

and 20.32-cm (8-inch)-spacing FRP dowels) under loading.
70 

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0 0.5 1 1.5 2 2.5 3

Loading Time (s)

Deflction (inches)

Side 1

Side 2

Fully loaded point

Deflection (in.):0.0018 (loaded)

0.0017 

(unloaded)

Relative Deflction (in.): 0.0001

LTE (%): 94.44%

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0 0.5 1 1.5 2 2.5 3

Loading Time (s)

Deflction (inches)

Side 1

Side 2

Fully loaded point

Deflection (in.):0.0018 (loaded)

0.0017 

(unloaded)

Relative Deflction (in.): 0.0001

LTE (%): 94.44%

1 inch = 2.54 cm 

Figure 84. Chart. Deflection on pavement joint 6 (with 2.54-cm (1.0-inch)-diameter 

and 15.24-cm (6-inch)-spacing FRP dowels) under loading. 

Summary and Analysis of Test Results 

A summary of the test results shown in figure 80 through figure 84 is provided in table 29 in 

terms of pavement deflection, LTE, and RD for pavement joints having 3.81- and 2.54-cm 

(1.5- and 1.0-inch)-diameter FRP dowels with different spacings of 30.48, 22.86, 20.32, and 

15.24 cm (12, 9, 8, and 6 inches). 
71 

Table 29. Summary of joint deflection under maximum loading force. 

Joint Number (Diameter 

and Spacing)— 

Refer to Table 28 

Pavement Deflection 

(10-4 inch) 

LTE 

(percent) 

RD 

(10-4 Loaded side inch) 

Unloaded 

side 

Joint 3 

(1.5 inch at 

12 inches c/c) 38 31 81.58 7

Joint 2 

1st and 2nd 

(1.5 inch at 

9 inches c/c) 

35 33 94.29 2

56 53 94.64 3

Joint 5 

(1.0 inch at 

8 inches c/c) 20 19 95.00 1

Joint 6 

(1.0 inch at 

6 inches c/c) 18 17 94.44 1

1 inch = 2.54 cm 

Values in table 29 cannot be compared to each other directly because, in addition to diameter and 

spacing, deflections depended on combinations of other parameters such as base/sub-base 

properties, contact area between concrete and base, and others. It should also be noted that truck 

wheel load position on dowels embedded in concrete may vary from one dowel to the other. 

The pavement surface was serrated to provide friction, and hence, there was the possibility of 

LVDT shaft tips sliding into those slots and showing slightly higher deflections. However, 

additional tests will be conducted in the future to compare LTE and RD. For this field test, LTE 

is shown in figure 85 and table 30, and RD is shown in figure 86 and table 31. 
72 

70

75

80

85

90

95

100

LTE (%)

LTE (%) 81.58 94.47 95 94.44

Joint3 Joint 2 Joint 5 Joint 6

Figure 85. Graph. Comparison of LTE from field test (average value was used for joint 2).

Table 30. Values for LTE comparison from field test. 

Joint 3 Joint 2 Joint 5 Joint 6 

LTE (percent) 81.58 94.47 95 94.44

Diameter 

(inches) 1.5 1.5 1.0 1.0

Spacing 

(inches) 12 9.0 8.0 6.0

1 inch = 2.54 cm 

Joint 3, with the largest dowel spacing of 30.48 cm (12 inches), had the lowest value of LTE 

among all tested joints (figure 84). It should be noted that small variations in deflection were 

being measured through LVDTs. Hence, additional field tests will be conducted in the future to 

ascertain LTE of joints with 30.48 cm (12 inches) of spacing. Table 32 compares LTE and RD 

from joint 2 and 3 testing. 
73 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Relative Deflection (x10 -3 inches)

Relative Deflection 0.7 0.25 0.1 0.1

Joint 3 Joint 2 Joint 5 Joint 6

1 inch = 2.54 cm 

Figure 86. Graph. Comparison of RD from field test (average value was used for joint 2).

Table 31. Comparison of RD values from field test. 

Joint 3 Joint 2 Joint 5 Joint 6 

Relative deflection 

(× 10-3 inch) 0.70 0.25 0.10 0.10

Diameter (inches) 1.5 1.5 1.0 1.0

Spacing (inches) 12 9.0 8.0 6.0

1 inch = 2.54 cm 

Table 32. Comparing joint 2 and 3. 

Joint 2, 

2.54 cm at 22.86 cm 

(1.5 inches at 

9 inches) c/c 

Joint 3, 

2.54 cm at 

30.48 cm 

(1.5 inches at 

12 inches) c/c 

Percentage of 

Difference 

(percent) 

LTE 94.47 81.58 15.8

Relative deflection 

(× 10-3 inch) 0.25 0.70 64.3

1 inch = 2.54 cm 

The following can be observed from this table: 

• Both 3.81-cm (1.5-inch)-diameter FRP dowel groups and 2.54-cm (1.0-inch)-diameter FRP 

dowel groups with spacing varying from 30.48 to 15.24 cm (12 to 6 inches) provided very 

good LTE (greater than LTE of 60 percent, which corresponds to ACPA’s 75 percent joint 

effectiveness value). 
74 

• For dowel groups in pavement joints 2 and 3 that had the same dowel diameter (3.81 cm 

(1.5 inches)), joint 2, with smaller dowel spacing (22.86 cm (9 inches)), had higher LTE 

(94 percent) than that provided by joint 3, with 30.48-cm (12-inch) dowel spacing 

(81.58 percent). Additional tests will be conducted on other joint locations. 

• Joint 2, with 22.86-cm (9-inch) dowel spacing, had smaller RD (6.35 × 10-3 mm 

(0.25 × 10-3 inch)) than joint 3, with 30.48-cm (12-inch) dowel spacing 

(17.78 × 10-3 mm (0.70 × 10-3 inch)) for a dowel diameter of 3.81 cm (1.5 inches). 

• Joint 2, with 22.86 cm (9 inches) of spacing), provided a 15.4-percent increase in LTE in 

addition to a 64.3-percent reduction in RD compared with joint 3, with 30.48-cm (12-inch) 

spacing for a dowel diameter of 3.81 cm (1.5 inches) (refer to table 28). 

• For pavement joints 5 and 6 (with 2.54-cm (1.0-inch) dowel diameters, 20.32- and 

15.24-cm (8.0- and 6.0-inch) dowel spacing, respectively), the LTEs were very close 

(95 percent and 94.44 percent). Relative joint deflections were also similar 

(2.54 × 10-3 cm (1 × 10-3 inch)). 

• Currently, there is no requirement or limitation for the RD from AASHTO’s Guide for 

Pavement Structures.

(1)

FRP DOWELS USED FOR HIGHWAY PAVEMENT REHABILITATION 

FRP dowels were used for pavement rehabilitation at the junction of Routes 119 and 857, 

University Avenue, Morgantown, WV. Two joints were selected; one with 3.81-cm (1.5-inch)-

diameter FRP dowels and 30.48-cm (12-inch)-c/c spacing, the other with 3.81-cm (1.5-inch)-

diameter steel dowels at 30.48-cm (12-inch)-c/c spacing. Dowel installation and field test setup 

are discussed in this section. Test results from both FRP and steel dowels are analyzed and 

discussed under the results and analysis subsection. 

Field Location 

Two joints were selected for rehabilitation of an existing pavement near the junction of Routes 

119 and 857, University Avenue, Morgantown, WV, as shown in figure 87. Rehabilitation was 

carried out in October 2002. 
75 

Two joints were 

selected for this study 

Figure 87. Photo. Locations of FRP and steel-doweled pavement joints. 

Field Installation 

Deteriorated concrete slabs were cut by a special concrete sawcutting machine and then lifted out. 

Next, 3.81-cm (1.5-inch)-diameter holes were drilled through the concrete slabs up to 

22.86 cm (9 inches) deep (half of dowel length). Each pavement joint consisted of 11 dowels 

with 3.81-cm (1.5-inch) diameters spaced at 30.48 cm (12 inches) c/c. Each joint was provided 

with two instrumented dowels. Strain gauges were bonded onto both top and bottom surfaces of 

those dowels prior to installation. Strain gauges were about 1.27 cm (0.5 inch) away from the 

centerline of the joint. 

After positioning dowels in the drilled holes, epoxy resin was filled into the circumferential gap 

between concrete and dowel. Rehabilitation carried out using FRP and steel dowels is shown in 

figure 88 through figure 91. 
76 

Figure 88. Photo. Drilling holes for inserting dowels.

Traffic 

Direction 

Dowel A Dowel B 

Figure 89. Photo. FRP dowels in position. 
77 

Traffic 

Direction 

Dowel C Dowel D 

Figure 90. Photo. Steel dowels in position. 

Figure 91. Photo. Concrete placement and vibration.

FIELD TESTS 

Test Setup 

A standard truck load was not used for field loading purposes. Strain readings due to regular 

traffic (figure 87), including some loaded trucks driving at 32.2–64.4 km/h (25–40 mi/h), were 

recorded using an automatic data acquisition system (figure 92). Due to the heavy traffic volume 

existing at this road section, pavement deflection measurements were not recorded. 
78 

Figure 92. Photo. Data acquisition recording strain readings.

Results and Analysis 

Both strain gauges were installed in the vehicle-approaching side (figure 89 through figure 91) of 

the pavement joint. Hence, before a vehicle wheel crossed the joint, the strain gauge side of the 

joint remained the loaded side, and, right after the wheel crossed a joint, the strain gauge side 

became the unloaded side. 

Strain readings due to a truck load from regular traffic are shown in figure 93 and figure 94. 

FRP Dowel Group 

Strain gauge readings from two instrumented FRP dowels (dowel A and dowel B in figure 89) 

are discussed in this section. Data from strain gauges mounted on top of these dowels are shown 

in figure 93. Note that not all data due to continuous traffic are plotted in figure 93; only strain 

values from a truck load with maximum values are shown. 
79 

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

345.3 345.5 345.7 345.9 346.1 346.3 346.5 346.7 346.9 347.1 347.3 347.5 347.7 347.9

Traffic Time (s)

Strain (microstrain

Dowel A

Dowel B

Unloaded 

Last wheel crossed the joint 

Loaded 

Peak Values under 

1st wheel load 

1st wheel load 2nd

 wheel load 

Figure 93. Chart. Strain from FRP dowels in rehabilitated pavement. 

Strain gauge data between recorded traffic time of 345.9 and 346.5 s correspond to the 

movement of the first wheel load. Due to truck load, maximum strains (-52.52 and 

-65.8 microstrain) occurred when the wheel loads were close to the joint in adjacent dowels. 

Based on strain values, it appears that the front axle carried more load than the rear axle, and 

vehicle impact factor could have also played a role. 

Strain gauge data between the recorded traffic time of 346.7 and 347.5 s correspond to the 

movement of the last wheel load crossing the joint. During this time period, gauges from FRP 

dowels A and B experienced a strain change from loaded status (-28.17 and -36.24 microstrain) 

to unloaded status (31.04 and 17.16 microstrain), respectively. The total strain change was 

59.21 (28.17 + 31.04) microstrain for dowel A and 53.4 (36.24 + 17.16) microstrain for dowel B. 

The ratio of unloaded value to loaded value was 31.04/28.17 = 1.10 (dowel A) and 17.16/36.24 = 

0.47 (dowel B). These ratios indicate the possibility of the wheel loads crossing at an angle over 

the dowel. It should be noted that the pavement was on an upward gradient with respect to traffic 

direction. 

Steel Dowel Group 

Strain gauge readings from one instrumented steel dowel (dowel C in figure 90) are discussed 

here. Data from the strain gauge mounted on top of this dowel are shown in figure 94. Note that 

not all data due to continuous traffic are plotted in figure 94; only strain values in dowel C from 

a truck load with maximum values are shown. 
80 

-25

-20

-15

-10

-5

0

5

10

15

151 151.2 151.4 151.6 151.8 152 152.2 152.4

Traffic Time (s)

Strain (microstrain)

Dowel C

1st wheel load 2nd

 wheel load 

Unloaded 

Loaded

Peak value under 

1st wheel load 

Figure 94. Chart. Strain from steel dowel in rehabilitated pavement. 

Strain gauge data between traffic time 151.2 and 151.6 s correspond to the movement of the first 

wheel load crossing the joint. Maximum compressive strains occurred at the beginning of the 

load, which was -11.49 microstrain, which may partly include vehicle impact effect. 

Strain gauge data between traffic time 151.8 and 152.2 s correspond to the movement of the last 

wheel load crossing the joint. During this time period, gauges from steel dowel C experienced a 

strain change from loaded status (-8.14 microstrain) to unloaded status (12.93 microstrain), 

respectively. The total strain change was 21.07 (8.14 + 12.93) microstrain for dowel C. The ratio 

of unloaded value to loaded value was 12.93/8.14 = 1.59 (dowel C). The following factors 

contributed to this ratio of unloaded/loaded strain > 1, where readings appeared to be from those 

vehicles just beginning to accelerate from their stopped position near traffic lights at junction: 

• Pavement rehabilitated with dowels was situated on an upward gradient. 

• Dowels on the upward portion of the joint were bonded to the concrete with epoxy. 

CONCLUSION 

From both the first and second field tests conducted on the newly constructed highway in Elkins, 

WV (see chapter 5), it is concluded that change in strain value for the same dowel during loading 

and unloading cases was almost the same. 

Effect of Dowel Spacing 

• For dowel groups in pavement joints 2 and 3 that had the same dowel diameter (3.81 cm 

(1.5 inches)), joint 2, with smaller dowel spacing (22.86 cm (9 inches)), had higher LTE 

(94 percent) than that provided by joint 3, with 30.48-cm (12-inch) dowel spacing 

(81.58 percent). This was attributed to the smaller dowel spacing used in joint 2, which 

resulted in more dowels sharing the load within the radius of relative stiffness. In addition, 
81 

the larger-than-expected difference in LTE for 22.86-cm (9-inch) and 30.48-cm (12-inch) 

spacing will be investigated in future tests. 

• Joint 2, with 3.81-cm (1.5-inch)-diameter dowels and 22.86-cm (9-inch) spacing, had smaller 

RD (6.35 × 10-3 mm (0.25 × 10-3 inch)) than joint 3, with the same diameter bar and 

30.48-cm (12-inch) spacing (17.78 × 10-3 mm (0.70 × 10-3 inch)). 

• Joint 2, with 3.81-cm (1.5-inch)-diameter dowels and 22.86-cm (9-inch) spacing, provided a 

15.4-percent increase in LTE in addition to a 64.3-percent reduction in RD compared with 

joint 3, with 3.81-cm (1.5-inch)-diameter dowels and 30.48-cm (12-inch) spacing; refer to 

table 28. 

• For pavement joints 5 and 6 with 2.54-cm (1.0-inch)-dowel diameter, 20.32-cm (8.0-inch) 

and 15.24-cm (6.0-inch) dowel spacing, respectively, the LTEs were very close (95 and 

94.44 percent). Relative joint deflections were also similar (2.54 × 10-3 cm (1 × 10-3 inch)). 

• For FRP dowels (A1 and A2) with 2.54-cm (1.5-inch) diameters, dowel A2 with larger 

spacing (30.48 cm (12 inches)) had a greater strain change (31 microstrain) than dowel A1 

with 22.86-cm (9-inch) spacing (9 microstrain). Similarly, for FRP dowels C5 and C6 with 

the same 2.54-cm (1.0-inch) diameter, the dowel C5 with smaller spacing (15.24 cm 

(6 inches)) showed small strain change compared to C6 with 20.32-cm (8-inch) dowel 

spacing (3 versus 60 microstrain). 

• Thus, decreasing the spacing by 25 percent (30.48 to 22.86 cm (12 to 9 inches) and 

20.32 cm to 15.24 cm (8 to 6 inches)) resulted in more dowels sharing the load within the 

radius of relative stiffness (lr, chapter 6), leading to 30 percent or higher strain reductions in 

dowels. 

• For FRP dowels with 2.54-cm (1.0-inch) diameters (C5 and C6), the spacing increase from 

15.24 to 20.32 cm (6 to 8 inches) had a greater influence on strain value change (3 versus 

60 microstrain) than the increase of spacing from 22.86 to 30.48 cm (9 to 12 inches) in 

dowels (A1 and A2) with 3.81-cm (1.5-inch) diameters (9 versus 31 microstrain). 

• Dowels with different diameters and spacing could not be compared directly by strain value 

only. Because FRP dowels act as a group, spacing and diameter are both important factors 

for the group action. It should be also noted that FRP dowels with smaller diameters typically 

had better mechanical properties per unit area than larger-diameter dowels due to shear lag 

effects (refer to chapter 6). 

• Dynamic test results recorded contained significant noise, and hence, data are not further 

discussed. 

Effect of Dowel Diameter 

Both 3.81-cm (1.5-inch)-diameter FRP dowel groups and 2.54-cm (1.0-inch)-diameter FRP 

dowel groups with spacing varying from 30.48 to 15.24 cm (12 to 6 inches) provided very 

good LTE (greater than LTE of 60 percent, which corresponds to ACPA’s 75 percent joint 
82 

effectiveness value). Currently, there is no requirement or limitation for the RD from 

AASHTO’s Guide for Pavement Structures.

(1) From field tests, the maximum RD was 

17.78 × 10-3 mm (0.70 × 10-3 inch), but, from lab testing, it was a maximum of 

10.922 × 10-3 mm (43 × 10-3 inch) (table 16). It should be noted that joint width was due to 

different joint models and thermal variables. 

From field tests conducted on the rehabilitated pavement in Morgantown, WV (see chapter 5), 

the following is concluded: 

• Strains at loaded and unloaded status from FRP dowels (A and B) (28.17 and 36.24 microstrain) were greater than that from steel dowels (C) (11.49 microstrains), which conforms to 

the analytical finding that shorter lengths are required for FRP dowels than for steel dowels 

(refer to figure 108). 

• The strain value ratio from the same gauge at unloaded status to loaded status did not 

represent real LTE. 

• It was suggested that LTE should be discovered from measuring pavement deflection. 
83

CHAPTER 6. ANALYTICAL EVALUATION 

INTRODUCTION 

Pavement performance (RD and LTE) in JPCP with the FRP dowel as the load transfer device 

depends on many design parameters such as dowel diameter, dowel spacing, joint width between 

adjacent slabs, pavement thickness, concrete strength, base and sub-base properties, and 

environmental conditions including temperature variation. In this chapter, analytical evaluation is 

carried out for pavement slabs with FRP dowels. 

Several examples provided in this chapter illustrate computations for group action of dowels, 

maximum bending and shear deflection of dowels, pavement RD, and bearing stresses. Both 

steel and FRP dowels are used for comparison. 

The expansion joint model is used as the analytical model; the contraction joint model is also 

discussed and compared. 

ANALYTICAL MODEL 

Computations for a JPCP are carried out by assuming the dowel to be a beam and the concrete to 

be a Winkler foundation. Based on the original solution by Timoshenko and Lessels for the 

analysis of beams on an elastic foundation, the differential equation of the deflection of a beam 

on an elastic foundation is given as follows:(11)

ky dx

yd El −= 4

4

(4)

In equation 4, k is the modulus of foundation, a constant, and y is the deflection. The modulus of 

foundation denotes the reaction due to load per unit length when the deflection is equal to unity. 

Timoshenko and Lessels gave a solution to the differential equation as follows (equation 5):(13)

( ) ( xDxCexBxAe y ) x x ββ ββ β β = cos sin ++ cos + sin −

(5)

Where beta is defined as the following (equation 6): 

4

4 EI

k β = (6)

With relative stiffness of a dowel embedded in concrete, where: 

k = Modulus of foundation (MPa (psi)). 

E = Modulus of elasticity of the beam (MPa (psi)). 

I = Moment of inertia of the beam (cm4 (inches4)). 

A, B, C, and D are constants determined from the boundary conditions for a particular beam on 

an elastic foundation. For a semi-infinite beam on an elastic foundation subject to a point load 
84

and moment applied at its end, as shown in figure 95, constants A and B are equal to zero and C

and D are equal to the following (equation 7): 

C = D = 

EI

P

3 8 β (7)

After substituting A, B, C, and D (equation 8), equation 5 becomes the following: 

[ ] ( ) xxMxP

El

e

y

x

ββββ β

β

cos sincos

2 = 3 − 0 −

−

(8) 

Loads P and M0 are positive in figure 95. By considering downward deflection as positive and 

the differentiating equation in equation 8 with respect to x gives slope, dy/dx, of the beam along 

its axis, as follows (equation 9): 

[ ] ( ) xPxPM

El

e

dx

dy x

β ββ β

β

2 cos sin

2 = 2 0 − −

−

(9)

M0 P

x

y

Beam Elastic 

Foundation

Figure 95. Diagram. Semi-infinite beam on an elastic foundation. 

Applying the solution for a semi-infinite beam on an elastic foundation to dowel bars, Friberg 

developed equations for determining the slope and deflection of a dowel at the face of a joint as 

shown in figure 96.(14)
85

Dowel

Base

P Pavement t

y0

z/2

Deflected shape

Figure 96. Diagram. Slope and deflection of dowel at joint face. 

Substituting –Ptz/2 for M0 (equation 10) and setting x equal to zero in equation 8, slope dy0/dx

and the maximum deflection, y0, of the dowel at the face of the joint are given by equation 11 

and equation 12, respectively.(14)

2 0

zP M − t = (10)

( )z

IE

p

dx

dy

dd

t β β

+ − = 1

2 2

0

(11)

( )

dd

t

IE

zP

y0 3 4

2

β

+ β = (12)

Where: 

β = Relative stiffness of the dowel bar encased in concrete (cm-1 (inch-1)). 

K0 = Modulus of dowel support (kg/cm3 (pci)). 

Ed = Modulus of elasticity of the dowel bar (MPa (psi)). 

Id = Moment of inertia of the dowel bar (cm4 (inch4)). 

Pt = Load transferred through the dowel (metric ton (lb)). 

d = Diameter of dowel bar (cm (inch)). 

z = Joint width (cm (inch)). 
86

Friberg replaced the modulus of foundation k with the expression K0d. The modulus of dowel 

support, K0, denotes the reaction per unit area due to applied load when the deflection is equal to 

unity. Thus, relative stiffness of a dowel embedded in concrete, β , is given by (equation 13):(14)

4 0

4 dd IE

dK β = (13)

K0 is an important parameter in Friberg’s design equation. K0 is determined empirically because 

of the difficulty in establishing it theoretically.(14) Literature reviews indicate a wide range of 

values for the modulus of dowel support. Modulus of dowel support K0 increases with increased 

concrete strength (fc′), decreases with increased concrete depth below the dowel, and decreases 

with increased dowel bar diameter. Yoder and Witczak found that K0 ranges between 300,000 

and 1.5 million pci (8,303.972 and 41,519.858 kg/cm3

). For analytical calculations in this chapter, 

a value of 1.5 million pci (41,519.858 kg/cm3

) is used as suggested by Yoder and Witczak to 

simulate the worst scenario.(15)

Friberg’s equations were derived assuming a dowel bar of semi-infinite length.(14) Dowel bars 

used in practice are of finite length (typically a total length of 45.72 cm (18 inches)); therefore, 

this equation would not apply. However, Albertson and others have shown that this equation can 

still be applied to dowel bars with a β L value greater than or equal to 2 with little or no error, 

where the length of the dowel bar embedded in one side of the slab is denoted as L.

(16)

Load Transfer Across a Joint 

If 100 percent LTE is achieved by the dowel bars, about 50 percent of the wheel load would be 

transferred to the subgrade while the other 50 percent would be transferred through the dowels to 

the adjacent slab. However, repetitive loading of the joint results in the creation of a void directly 

above or beneath the dowel at the face of the joint. According to Yoder and Witczak, a 

5–10 percent reduction in load transfer occurs upon formation of this void; therefore, a design 

load transfer of 45 percent of the applied wheel load is recommended (equation 14).(15)

t PP w = 45.0 (14)

Where: 

Pt = Load transferred across the joint (metric ton (lb)) 

Pw = Applied wheel load (metric ton (lb)). 

Based on Westergaard’s solutions, Friberg found that only the dowels contained within a 

distance of 1.8 lr from the load carried the applied load, where lr is the radius of relative stiffness,

defined as the stiffness of the slab relative to the stiffness of the foundation.(17) Radius of relative 

stiffness (lr) is determined by the following formula (equation 15): 

( ) 4

2

3

112 kv

hE l c

r − = (15)
87

Where: 

Ec = Modulus of elasticity of the pavement concrete (MPa (psi)).

Ec = 57,000(fc′)

0.5. 

h = Pavement thickness (cm (inch)). 

ν = Poisson’s ratio for the pavement concrete. 

k = Modulus of subgrade reaction (g/cm3 (pci)). 

The modulus of subgrade reaction k is a measure of the strength of the supporting soil 

(equation 16), which may be the sub-base or the subgrade. Its value is given in kilograms per 

cubic centimeter (kg/cm3

) (pounds per square inch per inch (pci)) deflection as shown in 

1 pci = 0.02768 kg/cm3

. 

( ) pci soil deflection

soil pressure k =

1 pci = 0.02768 kg/cm3

 (16) 

A linear distribution of the load transferred across the joint is typically used, as shown in 

figure 97: 

1.0Pc

0.0Pc

critical 

dowel

Pw

Pc 0.0PPcc

Pc

Figure 97. Diagram. Load transfer distribution proposed by Friberg.(14)

However, Tabatabaie et al. found that an effective length of 1.0 lr from the applied wheel load is 

more appropriate for dowels used in practice today (figure 98). A linear approximation was also 

shown to exist with the maximum dowel shear occurring directly beneath the load and 

decreasing to a value of zero at a distance 1.0 lr from the load.(18)
88

1.0Pc

0.0Pc

critical 

dowel

Pw

0.0Pc

1.0lr 1.0lr

Figure 98. Diagram. Load transfer distribution proposed by Tabatabaie et al.(18)

From figure 99, the most critical case is that of the critical dowel being located at the edge of a slab. 

1.0Pc

0.0Pc

critical 

dowel

Pw

1.0lr

Figure 99. Diagram. Most critical dowel at the edge of a slab. 

If the force transferred by a critical dowel, which is located directly beneath the wheel load, is 

designated as Pc, then the shear force in any other dowel within lr is determined by multiplying 

the height of the triangle below that particular dowel by Pc. A value of 1.0 is assumed for the 

height of the triangle directly below the load, as shown in figure 98. The shear force in the dowel 

directly under the load is obtained by dividing the transferred load, Pt, by the number of effective 

dowels, as shown in equation 17. The sum of the heights of the triangle under each dowel within

lr gives the number of effective dowels. 

dowels effective ofnumber 

t

c

P P = (17)
89

Dowel Bending Moment and Shear 

The bending moment (equation 18) and shear force (equation 19) along the dowel from the face 

of the joint can be expressed as follows: 

( ) [ ] ( ) xxMxP e

dx

yd IExM t

x

dd ββββ β

β

sin cossin 2 0

2

− + − −= =

−

(18)

( ) [ ] ( ) xPxPMe

dx

dM xV t t

x β ββ β 2 sin cos −== 0 − + −

(19)

Where: 

x = Distance along dowel from face of concrete (cm (inch)). 

M0 = Bending moment on dowel at face of concrete (see equation 10). 

Pt = Transferred load. 

Ed Id = Flexural rigidity of dowel. 

Dowel Bar Deflection and Bearing Stress 

The RD between slabs is shown in figure 100, and the expression of Δ is shown in equation 20. 

Figure 100. Diagram. RD between concrete slabs (Porter and Guinn).(19)
90

EI

Pz

dx

dy zy 12

2

3

0

0 ⎟ ++⎠

⎞ ⎜

⎝

⎛ +=Δ δ

(20) 

Where: 

y0 = Dowel deflection (from equation 12). 

⎟

⎠

⎞ ⎜

⎝

⎛

dx

dy

z 0

= Deflection due to the slope of dowel 

AG

λ tzP δ =

 (21) 

Where: 

λ = Form factor, equal to 10/9 for solid circular section. 

A = Cross-sectional area of the dowel bar. 

G = Shear modulus. 

Pt = Load transferred by critical dowel. 

z = Joint width. 

EI

Pz

12

3

 = Flexural deflection. 

For small joint width, deflections due to slope and flexure are very small, thus neglecting those 

terms in equation 20 and obtaining equation 22, as follows: 

Δ = 2y0 +δ (22)

Bearing Stress Between Dowel/Concrete Interfaces 

The load acting on a dowel is transferred to the supporting/embedding concrete through bearing. 

Assuming the dowel behaves as a beam on an elastic foundation, the bearing stress at the face of 

the joint σ b is proportional to the deformation as shown in equation 23, as follows: 

dd

b c IE

z KPKy0 3 42

β

β σ+ ==

(23)

The bearing stress defined by equation 23 should not exceed the allowable value. The following 

equation 24 was given by American Concrete Institute’s (ACI) Committee 325.(20)

( )

3

4 ′ − = c

b

fd f (24)

Where: 

fb = Allowable bearing stress (MPa (psi)). 

d = Dowel diameter (cm (inch)). 

fc′ = Ultimate compressive strength of concrete slab (MPa (psi)). 
91

Pavement Joint Efficiency 

Joint efficiency is determined by the pavement’s ability to transfer part of an applied load across 

the joint to the adjacent slab. AASHTO and ACPA use deflection measurements to determine the 

efficiency of a joint. Equation 25 is given by ACPA as a means of rating joint effectiveness.(11)

%100 2×

+ =

UL

U

dd

d E

 (25)

Where: 

E = Joint effectiveness (percent). 

dU = Deflection of the unloaded side of a joint (cm (inch)). 

dL = Deflection of the loaded side of a joint (cm (inch)). 

A joint effectiveness of 75 percent or more is considered adequate for medium to heavy truck 

loadings. AASHTO adopts the 75 percent criteria and gives equation 26 for determining joint 

effectiveness associated with a 4.082-metric ton (9,000-lb) wheel load, as follows:(1) 

×= %100

L

U

d

d LTE

 (26) 

Where: 

LTE = Load transfer efficiency (percent). 

AASHTO also suggests that a LTE value between 70 and 100 percent is very good load transfer; 

the joint provides sufficient load transfer.(1) Deflection measurements for use in equations 25 and 

26 should be taken at the location of the outside wheel path. 

However, LTE and E are related by equation 27: 

%1001

2

2 ⎟×

⎠

⎞ ⎜

⎝

⎛ − − = E

LTE (27)

According to equation 3, an LTE of 60 percent corresponds to an E of 75 percent. When the 

value of LTE is between 60 and 100 percent, the joint still provides sufficient load transfer for 

heavy load. 

In this research, the joint LTE defined by AASHTO will be used to evaluate the performance of 

jointed pavements containing dowels. 
92

THEORETICAL CALCULATION SAMPLES FOR FRP AND STEEL DOWEL GROUP 

Calculations have been carried out for two dowel diameters (3.81 m (1.5 inches) and 2.54 cm 

(1.0 inch) for both FRP and steel dowels. Other parameters considered for calculation are listed 

in examples 1 through 4. 

Theoretical Calculation for Dowel Group with 3.81-cm (1.5-inch)-Diameter Dowels 

Theoretical calculations for concrete pavement joints having FRP and steel dowels with 3.81-cm 

(1.5-inch) diameter (figure 101) are provided in examples 1 through 4. 

joint Width, z

Dowel

Base

Pavement

Figure 101. Diagram. Expansion joint model used for theoretical calculation. 

Example 1 

Example 1 calculates the following items for concrete pavement having 3.81-cm (1.5-inch)-

diameter FRP dowels: 

1. Radius of relative stiffness. 

2. Number of effective dowels. 

3. Load carried by the critical dowel. 

4. RD Δ between joints. 

5. Bearing stress on dowel-concrete interface. 

Note that parameters listed below correspond to actual laboratory setup and/or field values that 

provide with useful comparisons. 

• FRP dowel. 

o Diameter, d = 3.81 cm (1.5 inches). 
93

o Length, L= 45.92 cm (18 inches). 

o Spacing between each dowel, b = 30.48 cm (12.0 inches). 

o Modulus of elasticity, Ed = 37.921 MPa (5.5 × 106

 psi). 

o Shear modulus of dowel, G = 2.8 × 104

 MPa (0.4 × 106 psi). 

o Moment of inertia of the dowel (equation 28), 

Id

3436.01

64

4

= × = π d

 (cm4) (0.248505 in4) (28) 

o Cross-sectional area of dowel, A = 4.496 cm2 (1.77 inches2). 

• Concrete pavement. 

o Compressive strength, fc′ = 31.026 MPa (4,500 psi). 

o Modulus of elasticity (equation 29), 

Ec = 

5.0 57,000 )'( c × f

= 26,363.319 MPa (3,823,676.2 psi) 

= 2.64 × 104 MPa (3.82 × 106 psi) (29) 

o Pavement thickness, h = 27.94 cm (11 inches). 

o Joint width, z = 0.635 mm (0.25 inch). 

o Poisson’s ratio of concrete, ν = 0.2. 

o Modulus of dowel support, K0 = 41,519.858 kg/cm3

 (1.5 million) pci. 

• Base. 

o Modulus of subgrade reaction, k = 11.072 kg/cm3

 (400 pci). 

• Load. 

o Design traffic load HS25, applied wheel load Pw = 9.071 metric tons (20,000 lbs). 

o Design load transfer by joint = 45 percent. 

o Pt = load transferred across the joint = Pw × 0.45 = 4.082 metric tons (9,000 lbs). 

Ec = 57,000 × (fc′)

0.5 
94

Calculation steps are shown in the following flow chart with equations (figure 102). 

Figure 102. Diagram. Steps for calculating critical dowel load, joint RD, and bearing stress 

in JPCP. 

Details of the calculations are given below from step 1 to step 5. 

Step 1. Calculation for radius of relative stiffness (equation 30): 

4

2

3

)1(12 k

hE l c

r −ν = 4

2

3

400)2.01(12

3823676 11

×−×

× = (from equation 15)

= 82.34172 cm (32.4180 inches). (30) 

Step 2. Calculation for number of effective dowels: 

The dowels within 1.0 lr distance are effective in load distribution (see figure 98). Number of 

dowels in 1.0 lr distance (equation 31): 

= 2 × INT (lr/b = 32.4180/12.0 = 2.7) +1 

= 2 × 2 + 1 = 5 (31) 

Where: 

lr = Radius of relative stiffness. 

b = Dowel spacing. 

The critical dowel in this dowel group, which is the dowel directly under the load, has an effect 

of 1.0 (figure 98 and figure 99), and other dowel contributions were calculated according to the 

triangular ratio. Load was distributed on five dowels (one critical dowel plus two effective 
95

dowels on each side) by a triangular variation with due consideration to the available pavement 

width (see figure 103). 

1.0Pc

critical 

dowel

w

1.0lr 1.0lr

Figure 103. Diagram. Generalized effective dowels for load distribution. 

In order to obtain the most critical load condition, it is assumed that the critical dowel is located 

on the edge of the pavement. Thus, the effective dowel number is reduced to three (one critical 

dowel and two effective dowels on one side) (see figure 104). 

critical 

dowel

1.0Pc

w

1.0lr

0.6298Pc

0.2597Pc

Figure 104. Diagram. Most critical load distribution on effective dowels. 

 

From calculations, the number of effective dowels = 1.0 + 0.6298 + 0.2597 = 18,895. 
96

Step 3. Calculation for load carried by the critical dowel: 

When wheel load is applied at the edge of the pavement, the critical dowel has to carry most of 

the transferred load as shown in equation 32 (from equation 17 and figure 97): 

ofnumber effective dowels

t

c

P

P =

= 4.082 metric tons (9,000 lb)/1.8895 = 2.1604 metric tons (4,763 lb) (32) 

Note, that to obtain the same critical load for lab experiments, the following is necessary at the 

loaded side of the pavement: 

%45

Pc

 = 4.802 metric tons (10,584.7716 lb) 

Step 4. Calculation for RD Δ between joints (from equation 12): 

Maximum dowel deflection, as follows: 

dd

c

IE

zP

y 0 3 4

)2(

β

+ β =

800952.40 2485.0105

800952.02(1472.4763 )25.0

3 6 ×××

× + × =

(= 0.0037307 inches)

= 0.009475978 cm (33) 

Where (from equation 13): 

4 0

4 dd IE

dK β =

4

6 5.54 10 .0 2485

,1 500 ,000 5.1

×××

× =

(= 0.80095168 inch-1)

= 0.315335 cm-1 (34) 

Dowel shear deflection (from equation 21), as follows: 

AG

λ c zP δ = 5 10477.1

25.01472.4763)910(

× ×

÷ × × =

(= 0.00187 inch)

= 0.004750 cm (35) 

Where: 

λ = Form factor, equal to 10/9 for solid circular section. 
97

So, total RD between pavement joints is (from equation 22) is shown in equation 36: 

Δ = 2 y0 + δ

= 2 × 0.0037307 + 0.00187 

(= 0.00933 inch) 

= 0.0236982 cm (36) 

Step 5. Calculation for bearing stress on dowel-concrete interface: 

Maximum bearing stress occurs at the place where deflection is maximum (from equation 23) as 

calculated in equation 37. 

0 y σ b = Κ

=1,500,000 × 0.0037307 

 (= 5596.05 psi) 

= 38.583 MPa (37) 

The allowable bearing stress is (from equation 24) as calculated in equation 38: 

3

)4( '

c

b

fd f − =

3

×− ,4)5.14( 500 =

 (= 3750 psi) 

= 25.855 MPa (38) 

Thus, σ b > fb (5,596.05 > 3,750); the bearing stress limit is not satisfied. 

Discussion for Contraction Joint Model 

Theoretical equations derived for dowels from the expansion joint model include the shear 

deflection term (equation 39) due to the presence of joints with a width of 0.635 cm (0.25 inch). 

AG

λ c zP δ = (39) 

However, depth of contraction and construction joint model (figure 105) (typically 1⁄4 to 1⁄3 of the 

pavement thickness) will not reach the dowel surface because the dowel is always surrounded by 

concrete. To calculate these types of concrete pavement joints, the effective joint width z used 

for theoretical calculation will be much smaller than 0.635 cm (0.25 inch), say 0.0793 cm 

(0.0313 inch). This will result in less maximum bending deflection (y0) and much smaller shear 

deflection (equation 21) (see table 32 for detailed calculations). 
98

joint Width, z Pavement

Base

Dowel

Figure 105. Diagram. Pavement contraction joint model. 

Example 2 

Example 2 calculates the following items for concrete pavement having 3.81-cm (1.5-inch) steel 

dowels: 

1. Radius of relative stiffness. 

2. Number of effective dowels. 

3. Load carried by the critical dowel. 

4. RD Δ between joints. 

5. Bearing stress on dowel-concrete interface. 

Parameters used for calculation in example 2 are similar to those in example 1, except that the 

dowel parameters have been changed to steel dowel properties. 

Note that parameters listed below correspond to actual laboratory setup and/or field values that 

provide useful comparisons. 

• Steel dowel. 

o Diameter, d = 3.81 cm (1.5 inches). 

o Length, L = 45.72 cm (18 inches). 

o Spacing between each dowel, b = 30.48 cm (12.0 inches). 

o Modulus of elasticity, Ed = 20.0 × 104

 MPa (29 × 106 psi). 

o Shear modulus of dowel, G = 7.58 × 104

 MPa (11 × 106 psi). 
99

o Moment of inertia of the dowel bar, 

Id

10.3436

64

4

= × = π d

(cm

4

) (0.248505 in4) (40) 

o Cross-sectional area of dowel, A = 4.496 cm2

 (1.77 inches2). 

Calculation steps are the same as those for FRP dowel and are shown in figure 102. 

Step 1. Calculation for radius of relative stiffness (from example 1):

lr = 82.342 cm (32.418 inches). 

Step 2. Calculation for number of effective dowels (from example 1): 

Number of dowels = 2 × INT (lr/b = 32.418/12.0 = 2.7) +1 

= 2 × 2 + 1 = 5. 

Number of effective dowels = 1.0 + 0.6298 + 0.2597 = 1.8895. (41) 

Step 3. Calculation for load carried by the critical dowel (from example 1) as shown in 

equation 42: 

ofnumber effective dowels

Pt Pc =

= 9,000/1.8895 

(= 4,763.1472 lb) 

= 2.161 metric tons. (42) 

Note, that to obtain the same critical load for lab experiments, the calculation shown in 

equation 43 is necessary (from example 1) at the loaded side of the pavements. 

45%

Pc

(= 10,584.7716 lb) 

= 4.801 metric tons (43) 
100

Step 4. Calculation for RD Δ between joints is done by using equations 44 through equation 46, 

as follows: 

Maximum dowel deflection, 

dd

c

IE

zP

y 0 3

4

)2(

β

+ β =

.04 52856389 29 10 .0 2485

4763 .1472 .02( 52856389 .0 25 ) 3 6 × ×××

+× × =

(= 0.002386 inch)

= 0.006060 cm (44) 

Where: 

4

0

4 dd IE

dK β =

4

6 4 1029 .0 2485

,1 500 ,000 5.1

×××

× =

(= 0.52856389 inch-1)

= 1.404 cm-1. (45) 

Dowel shear deflection, 

AG

λ c zP δ = 

7 .1 77 1011

(10 ,4)9 763.1472 .0 25

××

×÷ × =

 (= 0.000007 inch) 

= 0.00001778 cm. 

Total RD ? = 2 × 0.002386+0.000007 = 0.012136 cm (0.004778 inch) (46) 

Step 5. Calculation for the bearing stress on dowel-concrete interface (from equation 23) is given 

by equation 47, as follows: 

0 y σ b = Κ

=1,500,000 × 0.002386

(= 3578.6247 psi) 

= 24.674 MPa. (47) 
101

The allowable bearing stress is (from equation 24) calculated from equation 48, as follows: 

3

)4( '

c b

fd f − =

3

− 4500)5.14( =

(= 3750 psi) 

= 25.855 MPa. (48) 

Thus, σ b < fb, 24.674 < 25.855 MPa (3,578.62 < 3,750 psi); the bearing stress limit is 

satisfied. 

Theoretical Calculation for Dowel Group with 2.54-cm (1.0-inch)-Diameter Dowels 

Theoretical calculations for concrete pavement joints having FRP and steel dowels with 2.54-cm 

(1.5-inch) diameter (figure 101) are provided in examples 3 and 4. The expansion joint model 

(figure 101) is used for calculations. For convenience, figure 101 is shown here again, as 

figure 106. 

joint Width, z

Dowel

Base

Pavement

Figure 106. Diagram. Expansion joint model used for theoretical calculation. 

Example 3 

Example 3 calculates the following items for concrete pavement having 2.54-cm (1.0-inch) FRP 

dowels: 

1. Radius of relative stiffness. 

2. Number of effective dowels. 

3. Load carried by the critical dowel. 

4. RD Δ between joints. 

5. Bearing stress on dowel-concrete interface. 
102

Note that parameters listed below correspond to actual laboratory setup and/or field values that 

provide useful comparisons: 

• FRP dowel. 

o Diameter, d = 2.54 cm (1.0 inch). 

o Length, L = 45.72 cm (18 inches). 

o Dowel spacing, b = 15.24 cm (6.0 inches). 

o Modulus of elasticity, Ed = 4.14 × 104 MPa (6.0 × 106 psi). 

o Shear modulus of dowel, G = 0.28 × 104 (0.4 × 106 psi). 

o Moment of inertia (equation 49), 

Id

2.043171

64

4

= × = π d

(cm

4

) (0.049087 in4) (49) 

o Cross-sectional area, A = 1.995 cm2 (0.7854 inch2). 

• Concrete pavement. 

o Compressive strength, fc′ = 31.026 MPa (4,500 psi). 

o Modulus of elasticity (equation 50), 

 

Ec = 5.0 57,000 )'( c × f

(= 3,823,676.2 psi = 3.82 × 106 psi) 

= 263,633,319 MPa = 2.64 × 104

 MPa (50) 

 

o Pavement thickness, h = 27.74 cm (11 inches). 

o Joint width, z = 0.635 cm (0.25 inch). 

o Poisson’s ratio of concrete, ν = 0.2. 

o Modulus of dowel support, K0 = 41,519.858 kg/cm3

 (1.5 million pci). 

• Base. 

o Modulus of subgrade reaction, k = 11.072 kg/cm3 (400 pci). 

• Load. 

o Design traffic load HS25, applied wheel load, Pw = 9.071 metric tons (20,000 lbs). 
103

o Design load transfer of 45 percent. 

o Pt = load transferred across the joint = 45 Pw × .0 = 4.082 metric tons (9,000 lb). 

Calculation steps are the same as examples 1 and 2 and are shown in figure 102. Details of the 

calculations are given below from step 1 to step 5. 

Step 1. Calculation for radius of relative stiffness (from equation 15): 

4

2

3

12 )1( k

hE l c

r −ν = 4

2

3

12 )2.01( 400

3823676 11

×−×

× =

 (= 32.4180 inches) 

= 82.342 cm (51) 

Step 2. Calculation for number of effective dowels: 

The dowels within 1.0 lr distance are effective in load distribution. For the case-critical dowel at 

slab edge (figure 107), the dowels number in 1.0 lr distance: 

= INT (lr /b = 32.4180/6.0 = 5.40) + 1

= 5 + 1 = 6, (52) 

Where: 

lr = Radius of relative stiffness. 

b = Dowel spacing. 

critical 

dowel

1.0Pc

Pw

1.0lr

0.0746Pc

0.2597Pc

0.4448Pc

0.6298Pc

0.8149Pc

Figure 107. Diagram. Most critical load distribution on effective dowels. 

From calculations, the number of effective dowels follows: 

 = 1+0.8149+0.6298+0.4448+0.2597+0.0746 

= 3.2237 
104

Step 3. Calculation for the load carried by the critical dowel: 

When wheel load is applied at the edge of the pavement, the critical dowel has to carry most of 

the transferred load (from equation 17): 

ofnumber effective dowels

Pt Pc =

= 9,000/3.2237 

(= 2791.7646 lbs) 

= 1.266 metric tons (53) 

Note that for slabs only containing two 2.54-cm (1.0-inch) FRP dowels, in order to obtain the 

same critical load for lab experiments, it is necessary to apply the following: 

45%

.00.1( 8149)×+ Pc

= 45%

+ .00.1( 8149)× 2791.76

(= 12,666.93 lbs) 

= 5.746 metric tons 

At loaded side of pavements in lab tests, two dowels are considered. 

Step 4. Calculation for the RD Δ between joints (from equation 12) is carried out in equation 54 

through equation 56, as follows: 

Maximum dowel deflection, 

dd

c

IE

zP

y 0 3 4

)2(

β

+ β =

.14 06225 6 10 .0 049087

2791 .76 .12( 06225 .0 25 ) 3 6 × ×××+× × =

 (= 0.00448 inch) 

= 0.011379 cm (54) 

Where (from equation 13): 

4 0

4 dd IE

dK β =

4

6 64 10 .0 049087

1500000 5.1

×××

× =

(= 1.0623 inch-1) 

= 2.698 cm-1 (55) 
105

Dowel shear deflection (from equation 21): 

AG

λ c zP δ = 6 .0 7854 4.0 10

(10 )9 2791.76 .025

××

÷ × × =

(= 0.002468 inch) 

 = 0.006269 cm (56) 

Where: 

λ = Form factor, equal to 10/9 for solid circular section. 

So, total RD (equation 57) between pavement joints is as follows (from equation 22): 

Δ = 2 y0 + δ = 2 × 0.0048 + 0.002468 

(= 0.01143 inch) 

= 0.029032 cm (57) 

Step 5. Calculation for the bearing stress on dowel-concrete interface: 

The maximum bearing stress (equation 58) happens at the place where the deflection is the 

maximum (from equation 23), 

0 y σ b = Κ

= 1,500,000 × 0.0048

= 6718.66 psi 

= 46.324 MPa (58) 

The allowable bearing stress (equation 59) is as follows (from equation 24): 

3

)4( '

c b

fd f − =

3

− )0.14( 4500 =

 (= 4500 psi) 

= 31.026 MPa (59) 

Thus, σb > fb, (46.324 > 31.026 MPa (6,718.66 > 4,500 psi)); the bearing stress limit is not 

satisfied. 

Discussion for Contraction Joint Model 

In order to meet the bearing stress limit by adjusting dowel spacing only, FRP dowel spacing 

should not exceed 9.144 cm (3.6 inches). See the detailed data in table 34. 
106

Detailed data of calculations for the contraction joint model (figure 105) are shown in table 34, 

where joint width z is used as 0.079 cm (0.03125 inches). 

Example 4 

Example 4 calculates the following items for concrete pavement having 2.54 cm (1.0 inch) steel 

dowels: 

1. Radius of relative stiffness. 

2. Number of effective dowels. 

3. Load carried by the critical dowel. 

4. RD Δ between joints. 

5. Bearing stress on dowel-concrete interface. 

Parameters used for calculation in example 4 are similar to those in example 3, except dowel 

parameters have been changed to steel dowel properties. 

Parameters listed below correspond to actual laboratory setup and/or field values that provide 

useful comparisons. 

 

• Steel dowel. 

o Diameter, d = 2.54 cm (1.0 inch). 

o Length, L= 45.72 cm (18 inches). 

o Spacing between each dowel, b = 30.48 cm (12.0 inches). 

o Modulus of elasticity, Ed = 20 × 104 MPa (29 × 106 psi). 

o Shear modulus of dowel, G = 7.58 × 104 MPa (11 × 106 psi). 

o Moment of inertia of the dowel bar (equation 60): 

Id 2.043171

64

4

= × = π d (cm4) (0.049087 inches4) 

 (60) 

o Cross-sectional area of dowel, A = 1.995 cm2 (0.7854 in2). 
107

Calculation steps are same as those in example 3, which are for FRP dowels. 

Step 1. Calculation for the radius of relative stiffness: 

lr = 82.342 cm (32.4180 inches). 

Step 2. Calculation for the number of effective dowels: 

The number of dowels = 6 

Number of effective dowels = 3.2237. 

Step 3. Calculation for the load carried by the critical dowel (equation 61): 

number of effective dowels

Pt Pc =

= 9000/3.2237 

(= 2791.7646 lb) 

= 1.266 metric tons. (61) 

Step 4. Calculation for the RDΔ between joints (equation 62 through equation 65): 

Maximum dowel deflection, 

dd

c

IE

zP

y 3 0 4

)2(

β

+ β =

.0 04909 6 1029 3 .04 7164

2791 .7676 .02( 7164 .0 25 )

× ×××

+× × =

(= 0.002906 inch) 

= 0.00738124 cm (62) 

Where: 

4 0

4 dd IE

dK β =

4

.0 04909 6 4 29 10

1500000 0.1

×××

× =

(= 0.716417 inch-1) 

= 1.819699 cm (63) 

Dowel shear deflection, 

AG

λ c zP δ =

(= 0.000009 inch)

= 0.00002286 cm (64) 
108

So, total RD between pavement joints follows: 

Δ = 2 y0 + δ = 2 × 0.002906 + 0.000009 (= 0.00582 inch) 

= 0.01478 cm (65) 

Step 5. Calculation for the bearing stress (equation 66) on dowel-concrete interface (from 

equation 23): 

0y σ b Κ=

= 1,500,000 × 0.002906

= 4358.3564 psi 

= 30.04981 MPa (66) 

The allowable bearing stress (equation 67) in this case according to ACI is (from equation 24): 

3

)4( '

c b

fd f − =

 (= 4,500 psi) 

 = 31.026 MPa (67) 

Thus, σb < fb, (30.04981 MPa < 31.026 MPa (4,358.3564 psi < 4,500 psi)); the bearing stress 

limit is satisfied. 

DISCUSSIONS ON 3.81-CM (1.5-INCH) AND 2.54-CM (1.0-INCH)-DIAMETER 

DOWELS 

Comparisons for 2.54-cm (1.5-inch)-Diameter Dowel Bars 

Additional calculations were conducted, and it was found that in order to meet the bearing stress 

criteria by adjusting dowel spacing only, FRP dowel spacing should not exceed 17.78 cm 

(7.0 inches). Detailed data are shown in table 32. Other calculation results are also summarized 

in table 33. 
109

Table 33. Calculation summaries for 3.81-cm (1.5-inch)-diameter dowel (k = 11.072 kg/cm3

(400 pci), fc′ = 31.026 MPa (4,500 psi)). 

Dowel 

Material 

Spacing 

(inches) 

Radius of 

Relative 

Stiffness 

lr (inches) 

Load 

Carried by 

Critical 

Dowel 

(lbs) 

Effective 

Dowel 

Number 

Maximum 

Deflection 

y0

(10-3 inch) 

Shear 

Deflection

δ

(10-3 inch) 

Relative 

Deflection

Δ

(10-3 inch) 

Bearing 

Stress 

σb

(psi) 

FRP 12 32.4180 4,763.15 1.8895 3.731 1.872 9.33 5,596.05 

Steel 12 32.4180 4,763.15 1.8895 2.386 0.007 4.78 3,578.62 

FRP 6 32.4180 2,791.76 3.2238 2.187 1.097 5.47 3,279.92 

FRP 7 32.4180 3,168.22 2.8407 2.481 1.245 6.21 3,722.21 

FRP∗ 12 32.4180 4,763.15 1.8895 3.434 0.234 7.10 5,150.39 

FRP∗∗ 7.5 32.4180 3,350.12 2.6865 2.415 0.165 4.99 3,622.48 

Note: Cases FRP∗ and FRP∗∗ are dowel groups in the contraction joint model with joint width z = 0.079375 cm 

(0.03125 inch). Shaded data indicate that bearing stress limit of 28.855 MPa (3,750 psi) in this case is satisfied. 

1 inch = 2.54 cm 

1 lb = 0.0004536 metric ton 

1 psi = 0.006895 MPa 

Peak bearing stress at one location does not take into account the stiffness match between FRP 

dowel and concrete, which allows better distribution of bearing stress leading to reduced bearing 

stress concentration. Table 34 and table 35 describe the detailed data. 

Table 34. Peak bearing stress and average bearing stress in dowel (3.81-cm (1.5-inch) 

diameter at 30.48 cm (12 inches) c/c) downward area. 

Maximum 

Deflection 

y0 

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Peak 

Bearing 

Stress 

(psi) 

Average 

Deflection 

in Dowel 

Downward 

Bending 

Area 

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Average 

Bearing 

Stress 

(psi) 

Average/ 

Peak 

Bearing 

Stress 

(percent) 

FRP 3.731 300,000 1,119.3 1.321 300,000 396.3 35.40 1,500,000 5,596.5 1,500,000 1,981.5 

Steel 2.386 300,000 715.8 0.871 300,000 261.3 36.50 1,500,000 3,578.6 1,500,000 1,307.1 

Note: In table 34, the downward dowel length of FRP and steel dowels ranges from 0 to 5.08 cm (0 to 2 inches) and 

0 to 7.62 cm (0 to 3 inches) (figure 108), respectively. The value of the modulus of dowel support ranges from 

8303.972 kg/cm3

 to 4,159,858 kg/cm3 (300,000 to 1.5 million pci).(15)

1 inch = 2.54 cm 

1 pci = 0.02768 kg/cm3 

1 psi = 0.006895 MPa 
110

Table 35. Peak bearing stress and average bearing stress within 2.54-cm (1-inch) dowel 

(3.81-cm (1.5-inch) diameter at 30.48 cm (12 inches) c/c) length from joint face. 

Maximum 

Deflection 

y0 

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Peak 

Bearing 

Stress 

(psi) 

Average 

Deflection 

Within 1.0- 

inch Distance 

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Average 

Bearing 

Stress 

(psi) 

Average/ 

Peak 

Bearing 

Stress 

(percent) 

FRP 3.731 300,000 1,119.3 2.275 300,000 682.5 60.98 1,500,000 5,596.5 1,500,000 3,412.5 

Steel 2.386 300,000 715.8 1.752 300,000 525.6 73.43 1,500,000 3,578.6 1,500,000 2,628.0 

Note: In table 35, average bearing stresses were calculated for dowel with 2.54-cm (1.0-inch) distance from the face 

of joint. 

1 inch = 2.54 cm 

1 pci = 0.02768 kg/cm3 

1 psi = 0.006895 MPa 

-0.004

-0.0035

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0 2 4 6 810

Dowel Bending Deflection (in.)

steel-12 " spacing

FRP-12" spacing

FRP-6 " spacing

FRP-7" spacing

FRP-12"contraction joint mod el

Minimum steel dowel length in the joint= 8.5 inches 

Minimum FRP dowel length in the joint= 5.5 inches 

1 inch = 2.54 cm 

Figure 108. Chart. Dowel deflected shape (2.54-cm (1.5-inch) diameter). 

The following can be found for a dowel with 2.54-cm (1.5-inch) diameter: 

Effect of Dowel Material 

• Equation 4 through equation 24 are developed primarily for concrete pavement with steel 

dowels. These equations do not take into account better stress distribution and stiffness match 

between FRP and concrete. For dowels with the same spacing, currently used equations 

provide a lower value of maximum dowel deflection (y0), dowel shear deflection (δ ), and 

RD (Δ ) for slabs with steel dowels as compared to those with FRP dowels. The bearing stress 

(σb) obtained from analytical evaluation needs to be modified to apply it to FRP dowels 

because of the lower stiffness of FRP over steel, thus leading to better stress distribution. 
111

• For same-design spacing (30.48 cm (12 inches)), the maximum bending deflection (y0) of 

FRP dowels is 56 percent more than that from steel dowels (0.00948 cm versus 0.00606 cm 

(0.003731 versus 0.002386 inches)). Due to larger shear deflection, the total RD of FRP 

dowels is 1.95 times the value from steel dowels (0.0236982 versus 0.012141 cm (0.00933 

versus 0.00478 milli-inches)). However, the total effective dowel number and load carried by 

corresponding dowels are the same (refer to table 33). 

Effect of Dowel Spacing 

• As per currently used equations to evaluate JPCP response to wheel load, FRP and steel 

dowels have identical values for radius of relative stiffness, number of effective dowels, and 

critical dowel load for a particular spacing. For example, pavement with 30.48-cm (12-inch)- 

c/c FRP and steel dowels having fc′ = 31.026 MPa (4,500 psi) and joint width of 0.635 cm 

(0.25 inches) will have identical lr (82.342 cm (32.4180 inches)), number of effective dowels 

(1.89), and critical dowel load (2.161 metric tons (4763.15 lbs)). 

• To evaluate the wheel load response of JPCP, smaller dowel spacing design will result in the 

same values for radius of relative stiffness, larger value for number of effective dowels, and 

lower value for critical dowel load as compared to larger dowel spacing. For example, 

pavement with 15.24-cm (6-inch)-c/c FRP and steel dowels having fc′ = 31.026 MPa 

(4,500 psi) and joint width of 0.635 cm (0.25 inches) will have identical lr (82.342 versus 

82.342 cm (32.42 versus 32.42 inches)), a larger number of effective dowels (3.22 versus 

1.89), and a lower critical dowel load (1.266 versus 2.161 metric tons (2791.76 versus 

4763.15 lb)) as compared to dowels with 30.48-cm (12-inch)-c/c spacing. 

• Only when spacings between FRP dowels (2.54-cm (1.5-inch) diameter) are reduced to less 

than 17.78 cm (7 inches) (refer to table 33) would dowel maximum bending deflection (y0) 

(6.269 × 10-3 cm (2.481 × 10-3 inch)) be close to the value (6.060 × 10-3 cm (2.386 × 

10-3 inch)) of steel dowels (3.81-cm (1.5-inch) diameter) with 30.48 cm (12-inch) spacing. 

Effect of Joint Width 

• Shear deflection depends on joint width and is significant for FRP dowels. For example, 

when joint width z = 0.635 cm (0.25 inches) with 30.48-cm (12-inch) dowel spacing, shear 

deflection of FRP dowel (δ ) is 1.872/9.33 = 20.06 percent of the total RD. Shear deflection 

of steel dowel with 0.635-cm (0.25-inch) joint width is only 0.15 percent (0.007/4.78) of its 

total RD. When joint width is reduced to 0.079375 cm (0.03125 inch) (FRP* case in 

table 33), the shear deflection of FRP dowels is only 3.30 percent (0.234/7.10) as compared 

to 20.06 percent (refer to table 33). 

• For same-diameter (3.81-cm (1.5-inch)) FRP dowels, use of the contraction joint model will 

greatly reduce the shear effect of dowels. For example, RD for joints with FRP dowel bars is 

greatly reduced (0.0389636 versus 0.019812 cm (0.015 34 versus 0.007 80 inch)) with the 

joint width of 0.635 cm (0.25 inches) reduced to 0.079375 cm (0.03125 inches). 
112

Effect of Dowel Length 

• Based on inflection points (from figure 108 and figure 109), the minimum total length 

needed for steel dowels is 43.18 cm (17 inches) (2 × 21.59 cm (8.5 inches)), whereas FRP 

dowel bars need a minimum length of 27.94 cm (11 inches) (2 × 13.97 cm (5.5 inches)). The 

required FRP dowel length is only 64.7 percent (11/17) of that of the steel dowel. 

Effect on Bearing Stress 

• For a given set of pavement properties in terms of fc′, thickness, joint width, dowel diameter, 

and spacing, pavement with FRP and steel dowels shows significant differences in deflection 

and bearing stress value. 

• Bearing stress around the dowel-concrete interface (3.81-cm (1.5-inch) diameter) is only 

associated with maximum bending deflection. In order to meet the bearing stress limit 

(25.856 MPa (3,750 psi) in this case), spacings for steel dowels (3.81-cm (1.5-inch) diameter) 

cannot exceed 30.48 cm (12 inches), whereas spacing for FRP dowels (3.81-cm (1.5-inch) 

diameter) should not be more than 17.78 cm (7 inches) (expansion joint) or 19.05 cm 

(7.5 inches) (contraction joint). 

• Peak bearing stress at the joint location does not take into account the stiffness match 

between FRP dowels and concrete, which allows better distribution of bearing stress leading 

to reduced bearing stress concentration (table 34 and table 35). Theoretical calculations 

indicate allowable stress is exceeded. However, for 3.81-cm (1.5-inch)-diameter FRP dowel 

bars with 30.48-cm (12-inch)-c/c spacing, the average bearing stress is only 35.4 percent (the 

distance from the joint face to the first reflection point) and 0.98 percent (within 2.54 cm 

(1 inch) distance from the joint face) of the peak bearing stress. 

Comparisons for 2.54-cm (1.0-inch)-Diameter Dowel Bars 

After additional calculations, it is found that in order to meet the bearing stress criteria by 

adjusting dowel spacing only, FRP dowel spacing should not exceed 9.398 cm (3.7 inches). For 

practical purposes, it will be adopted as 8.89 cm (3.5 inches). Detailed data are shown in table 34. 

Other calculation results are summarized in table 36. 
113

Table 36. Calculation summaries for 2.54-cm (1.0-inch)-diameter dowel 

(k = 11.0719 kg/cm3 (400 pci), fc′ = 31.026 MPa (4,500 psi)). 

Dowel 

Material 

Spacing 

(inches) 

Radius of 

Relative 

Stiffness 

lr (inches) 

Load 

Carried by 

Critical 

Dowel 

(lbs) 

Effective 

Dowel 

Number 

Maximum 

Deflection 

y0 

(10-3 inch) 

Shear 

Deflection δ

(10-3 inch) 

Relative 

Deflection 

Δ

(10-3 inch) 

Bearing

Stress σb

(psi) 

FRP 6 32.4180 2,791.76 3.2237 4.479 2.468 11.43 6,718.66 

Steel 6 32.4180 2,791.76 3.2237 2.906 0.009 5.82 4,358.36 

FRP 3.5 32.4180 1,750.43 5.1416 2.808 1.548 7.16 4,212.58 

FRP∗ 6 32.4180 2,791.76 3.2237 4.020 0.309 8.35 6,029.56 

FRP∗∗ 4 32.4180 1,974.54 4.5580 2.843 0.218 5.90 4,264.54 

Note: Cases FRP∗ and FRP∗∗ are the calculations for dowel groups in the contraction joint model with joint width 

z = 0.079375 cm (0.03125 inch). Shaded data indicate that bearing stress limit (31.026 MPa (4,500 psi) in this case) is 

satisfied. 

1 inch = 2.54 cm 

1 lb = 0.0004536 metric ton 

1 psi = 0.006895 MPa 

Peak bearing stress at one location does not take into account the stiffness match between FRP 

dowel and concrete, which allows better distribution of bearing stress, leading to reduced bearing 

stress concentration. Table 37 and table 38 describe the detailed data. 

Table 37. Peak bearing stress and average bearing stress in dowel ((2.54-cm (1.0-inch) 

diameter at 15.24 cm (6 inches) c/c) downward area. 

Material 

Maximum 

Deflection 

y0 

(10-3 inch) 

Modulus of 

Dowel 

Support 

(pci) 

Peak 

Bearing 

Stress 

(psi) 

Average 

Deflection in 

Dowel 

Downward 

Bending 

Area 

(10-3 inch) 

Modulus of 

Dowel 

Support 

(pci) 

Average 

Bearing 

Stress 

(psi) 

Average/ 

Peak Bearing 

Stress 

(percent) 

FRP 4.479 300,000 1,343.7 1.565 300,000 469.5 34.94 1,500,000 6,718.5 1,500,000 2,347.5 

Steel 2.906 300,000 871.8 1.159 300,000 347.7 39.88 1,500,000 4,358.4 1,500,000 1,739.1 

NOTE: In table 37, the downward dowel length of FRP and steel dowels ranges from 0 to 3.81 cm (0 to 1.5 inches) 

and 0 to 7.62 cm (0 to 2 inches)(figure 134), respectively. Values of modulus of dowel support range from 

8,303.972 to 4,159.858 kg/cm3

 (300,000 to 1.5 million pci).(15). 

1 inch = 2.54 cm 

1 pci = 0.02768 kg/cm3

1 psi = 0.006895 MPa 
114

Table 38. Peak bearing stress and average bearing stress within 2.54-cm (1-inch) dowel 

(2.54-cm (1.0-inch) diameter at 15.24 cm (6 inches) c/c) length from joint face. 

Material 

Maximum 

Deflection 

y0

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Peak 

Bearing 

Stress 

(psi) 

Average 

Deflection 

Within 

1.0-inch 

Distance 

(10-3 inch) 

Modulus 

of Dowel 

Support 

(pci) 

Average 

Bearing 

Stress 

(psi) 

Average/ 

Peak 

Bearing 

Stress 

(percent) 

FRP 4.479 300,000 1,343.7 2.259 300,000 677.7 50.44 1,500,000 6,718.5 1,500,000 3,388.5 

Steel 2.906 300,000 871.8 1.879 300,000 563.7 64.66 1,500,000 4,358.4 1,500,000 2,818.5 

Note: In table 37, average bearing stresses were calculated for dowels with 2.54 cm (1-inch) distance from the face of 

joint. 

1 inch = 2.54 cm 

1 pci = 0.02768 kg/cm3

1 psi = 0.006895 MPa 

-0.005

-0.004

-0.003

-0.002

-0.001

0.000

0.001

0 1 2 3 4 5 6 7 8 9 10

Deflection (inches)

steel-6" spacing

FRP-6" spacing

FRP-3.5" spacing

FRP-6"contraction joint model

Minimum steel dowel length in the joint= 6.5 inches 

Minimum FRP dowel length in the joint= 4.5 inches 

1 inch = 2.54 cm 

Figure 109. Chart. Dowel deflected shape. 
115

The following can be found for dowel with 2.54-cm (1.0-inch) diameter: 

Effect of Dowel Material 

• Based on equation 4 through equation 24, for dowels with the same spacing, steel dowels 

provide a lower value of maximum dowel deflection (y0), dowel shear deflection (δ ), RD (Δ ) 

and bearing stress (σb). 

• For the same-design spacing (15.24 cm (6 inches)), the maximum bending deflection (y0) of 

FRP dowels is 54.03 percent more than those from steel dowels (0.01137666 versus 

0.00738124 cm (4.479 versus 2.906 milli-inches)). Due to larger shear deflection, the total RD 

of FRP dowels is 1.96 times the value from steel dowels (0.0290322 versus 0.0147828 cm 

(11.43 versus 5.82 milli-inches)). 

Effect of Dowel Spacing 

• As per currently used equations (equation 4 through equation 24) to evaluate JPCP response 

to wheel load, FRP and steel dowels have identical values for radius of relative stiffness, 

number of effective dowels, and critical dowel load for a particular spacing. For example, 

pavement with 15.24-cm (6-inch)-c/c FRP and steel dowels having fc′ = 31.026 MPa 

(4,500 psi) and joint width of 0.635 cm (0.25 inches) will have an identical lr (82.342 cm 

(32.4180 inches)), number of effective dowels (3.2237), and critical dowel load (1.266 metric 

tons (2,791.76 lb)). 

• To evaluate wheel load response of JPCP, a smaller dowel spacing design will result in the 

same value for radius of relative stiffness, a larger value for number of effective dowels, and 

a lower value for critical dowel load as compared to larger dowel spacing. For example, 

pavement with 8.89-cm (3.5-inch)-c/c FRP and steel dowels having fc′ = 31.026 MPa 

(4,500 psi) and joint width of 0.635 cm (0.25 inch) will have identical lr (82.342 cm 

(32.4180 inches) versus 82.342 cm (32.4180 inches)), a larger number of effective dowels 

(5.1416 versus 3.2237) and a lower critical dowel load (0.7940 versus 1.266 metric tons 

(1,750.43 lb versus 2,791.76 lb)) as compared to dowels with 15.24-cm (6-inch)-c/c spacing. 

• Only when spacings between FRP dowels (2.54-cm (1.0-inch) diameter) are reduced to less 

than 8.89 cm (3.5 inches) (refer to table 36), dowel maximum bending deflection (y0) 

(7.132 × 10-3 cm (2.808 × 10-3 inch)) is close to the value (7.381 × 10-3 cm (2.906 × 

10-3 inch)) of steel dowels (3.81-cm (1.5-inch) diameter) with 15.24-cm (6-inch) spacing. 

Effect of Joint Width 

• Shear deflection depends on joint width and is significant for FRP dowels. For example, 

when joint width z = 0.0635 cm (0.25 inches) with 15.24-cm (6-inch) dowel spacing, shear 

deflection of FRP dowel (δ ) was 2.468/11.43 = 21.59 percent of the total RD. Shear 

deflection of steel dowel with 0.635-cm (0.25-inch) joint width was only 0.15 percent 

(0.009/5.82) of its total RD. When joint width was reduced to 0.079 375 cm (0.03125 inch) 
116

(FRP* case in table 33), the shear deflection of FRP dowels is only 3.70 percent (0.309/8.35) 

as compared to 21.59 percent (refer to table 34). 

• For same diameter (2.54-cm (1.0-inch)) FRP dowels, the contraction joint model will greatly 

reduce the shear effect of dowels. For example, RD for joints with FRP dowel bars are 

greatly reduced (0.029032 versus 0.021209 cm (11.43 versus 8.35 milli-inches)) with joint 

width of 0.0635 cm (0.25 inches) reduced to 0.079375 cm (0.03125 inch). 

Effect of Dowel Length 

• Based on inflection points (from figure 109), the minimum total length for steel dowels is 

33.02 cm (13 inches) (2 × 16.51 cm (2 × 6.5 inches)), but, for FRP dowel bars, the minimum 

length is 22.86 cm (9 inches) (2 × 11.43 cm (2 × 4.5 inches)). The required FRP dowel length 

is only 69.23 percent (9/13) of the required length of the steel dowel. 

Effect on Bearing Stress 

• For a given set of pavement properties in terms of fc′, thickness, joint width, dowel diameter, 

and spacing, pavement with FRP and steel dowels shows significant differences in deflection 

and bearing stress value. 

• Bearing stress around the dowel-concrete interface (2.54-cm (1.0-inch) diameter) is only 

associated with the maximum bending deflection. In order to meet the bearing stress limit 

(31.026 MPa (4,500 psi) in this case), spacings for steel dowels (2.54-cm (1.0-inch) diameter) 

cannot exceed 30.48 cm (12 inches), whereas spacing for FRP dowels (2.54-cm (1.0-inch) 

diameter) should not be more than 8.89 cm (3.5 inches) (expansion joint) or 10.16 cm 

(4.0 inches) (contraction joint). 

• For 2.54-cm (1.0-inch)-diameter FRP dowel bars with 15.24-cm (6-inch)-c/c spacing, the 

average bearing stress is only 34.94 percent (distance from the joint face to the first reflection 

point) and 50.44 percent (within 2.54 cm (1 inch) of the distance from the joint face) of the 

peak bearing stress (table 37 and table 38). 

COMPARISON OF EXPERIMENTAL VERSUS THEORETICAL DATA 

Experimental test results from slabs having normal crack formation were compared with 

theoretical calculations in table 39. As per the equations (equation 4 through equation 24) used in 

this chapter, only RDs from static testing were compared. 
117

Table 39. Comparison of experiments versus theory for slab RD in static testing under 

HS25 loading. 

Slab 

Experimental Data (10-3 inch) Theoretical Data (10-3 inch) 

Static 

Fatigue at 

2 million cycles K = 1.5 million pci K = 300,000 pci 

Number 1 (FRP 

dowel, 1.0 inch at 

6 inches c/c) 2.27 12.8 11.43 31.26

Number 4 (FRP 

dowel, 1.5 inch at 

12 inches c/c) 29 25 9.33 26.07

Number 5 (steel 

dowel, 1.5 inch at 

12 inches c/c) 11 11 4.78 15.7

1 inch = 2.54 cm 

1 pci = 0.027679905 kg/cm3

The following was found: 

• For static testing, RDs obtained in concrete slabs (number 4) with large FRP dowel spacing 

(30.48 cm (12 inches)) in laboratory tests were larger than those from theoretical calculations. 

Slab number 1 with two FRP dowel bars and small spacing (15.24 cm (6 inches)) had a 

smaller RD than that from the theory (refer to table 39). 

• After 2 million fatigue load cycles, RD of all three slabs were within the theoretical RD 

range calculated by using modulus of dowel support K from 8,303.972 to 41,519.857 kg/m3 

(300,000 to 1.5 million pci). 

• The assumption of analytical models does not consider the boundary condition of elastic 

foundation; in laboratory tests, both ends of concrete slabs were not constrained. Thus, 

during the testing, both ends were slightly lifted up. Also, the assumed “s” shape (figure 100) 

for deformation of dowel bars under loading may be more like the “v” shape for unrestrained 

slabs. Additional tests are necessary to correlate laboratory deflection to analytical 

evaluations. 

ANALYTICAL INVESTIGATION WITH RESPECT TO FRP DOWEL-CONCRETE 

BEARING STRESS 

More extensive analytical investigation for FRP dowel-concrete bearing stress was conducted. 

More parameters were considered for analysis by using constant values of FRP dowel material 

properties, as follows: 

• Concrete strength fc

′

: 20.684, 24.132, 27.579, and 31.026 MPa (3,000, 3,500, 4,000, and 

4,500 psi). 

• Concrete pavement thickness h: 25.4, 27.94, and 30.48 cm (10, 11, and 12 inches). 
118

• Concrete joint width z: 0.635 and 0.3175 (0.25 and 0.125 inches). 

• Dowel length: 30.48, 45.72, and 60.96 cm (12, 18, and 24 inches). 

• Dowel diameter d: 2.54, 4.45, 3.81, 4.45, and 5.08 cm (1, 1.25, 1.5, 1.75, and 2 inches). 

• Elasticity modulus of Dowel Ed: 3.79 × 104 and 4.14 × 104 MPa (5.5 × 106 and 6 × 106 psi). 

• Shear Modulus of Dowel G: 2.8 × 104 MPa (0.4 × 106 psi). 

• Dowel spacing b: 15.24, 20.32, 25.4, and 30.48 cm (6, 8, 10, and 12 inches). 

• Modulus of subgrade reaction k: 2.768, 11.072, and 22.144 kg/cm3 (100, 400, and 800 pci). 

• Modulus of subgrade reaction is a measure of the strength of the supporting soil, which may 

be the sub-base or the subgrade. Its value is given in kg/cm3 (lb/inch3

) of deflection. 

• Modulus of dowel supports Κ: 41,519.878 kg/cm3 (1.5 million pci). 

Following are some of the simplified conclusions drawn based on the theoretical analysis using 

the above parameters: 

Bearing stress (σb) can be reduced as follows: 

• By increasing the following: 

o Dowel diameter (d). 

o Pavement slab thickness (h). 

o Concrete strength (fc

′

). 

• By decreasing the following: 

o Dowel spacing (b). 

o Joint width (z). 

o Modulus of subgrade reaction (k). 

o Modulus of dowel support (Κ). 

Bearing stress (σb) cannot be significantly affected by the dowel length beyond a certain length; 

for FRP dowels, this length is 64.7 percent and 69.23 percent of steel dowels for 3.81- and 

2.54-cm (1.5- and 1.0-inch)-diameter dowels, respectively. 
119

Allowable bearing stress (fb) can be increased by the following: 

• Decreasing the dowel diameter (d). 

• Increasing the concrete strength (fc′). 

121

CHAPTER 7. CONCLUSIONS AND RECOMMENDATIONS 

INTRODUCTION 

In this research, FRP dowel bars with 3.81- and 2.54-cm (1.5- and 1.0-inch) diameters spaced at 

different intervals as load transferring devices in JPCP were evaluated under static and fatigue 

loads corresponding to HS25 trucks. Their responses were compared with JPCP consisting of 

steel dowels under laboratory and field conditions. Performance of JPCP rehabilitated with FRP 

and steel dowels was also evaluated. 

Analysis and discussions corresponding to experimental results and theoretical calculations are 

summarized in this chapter. 

CONCLUSIONS FOR LABORATORY TESTS 

Laboratory evaluations were carried out on contraction joints (figure 105) with FRP and steel 

dowels similar to field implementation. During laboratory tests, crack formations were noted 

under the joint (referred to as proper crack formation, figure 18) or away from the joint near 

dowel edges (figure 19 and figure 20). Proper crack formation at joint location was noted in 

slab number 1 (15.24-cm (6-inch)-c/c spacing for 2.54-cm (1.0-inch)-diameter FRP dowels), slab 

number 4 (30.48-cm (12-inch)-c/c spacing for 3.81-cm (1.5-inch)-diameter FRP dowels), and 

slab number 5 (30.48-cm (12-inch)-c/c spacing for 3.81-cm (1.5-inch)-diameter steel dowels). 

Crack formation at locations away from the joint and close to the edge of the dowel end was 

observed in slab number 2 (15.24-cm (6-inch)-c/c spacing for 2.54-cm (1.0-inch) diameter for 

steel dowels) and slab number 3 (15.24-cm (6-inch)-c/c spacing for 2.54-cm (1.5-inch) diameter 

for steel dowels). 

Results mainly focused on slabs with proper crack formation at the mid-joint. Conclusions on 

laboratory tests are provided with respect to the following: 

• RD. 

• LTE. 

• Pavement pumping. 

• Strains on dowels. 
122

Joint RD 

For Specimens (Numbers 1, 4, and 5) Having Proper Crack Formation at Joint Locations 

(Table 6) 

• For static testing, RD decreased by decreasing the dowel bar diameter and spacing 

(0.0577 cm (0.00227 inch), i.e., 2.54-cm (1.0-inch) diameter at 15.24 cm (6 inches) c/c 

versus 0.00738 cm (0.029 inch) for 3.81-cm (1.5-inch)-diameter FRP dowel at 30.48-cm 

(12-inch)-c/c spacing). 

• RD for slab number 4 reduced (0.00738 to 0.0635 cm (0.029 to 0.025 inch)) with the 

progression of the fatigue load from 0 to 2 million cycles. RD for slab number 5 remained the 

same (0.0278 cm (0.011 inch)). This is attributed partly to compaction/settlement of 

aggregate base underneath the pavement slabs with increasing fatigue cycles, resulting in 

smaller RD. It can also be attributed to similarities in stiffness between FRP 

(≈ 3.79 × 104

 MPa (5.5 × 106 psi)) and concrete (≈ 2.64 × 104 MPa (3.8 × 106 psi)). Benefits 

of these reductions may be more evident with freeze-thaw variations. 

• In static tests (table 14), RD in slab number 1 with two 2.54-cm (1.0-inch)-diameter FRP 

dowels had low RD (0.0577 cm (0.00227 inch)) corresponding to HS25 loading. Analytical 

values for RD were found to be larger than the experimental value (0.0212 cm (0.0084 inch) 

for the contraction joint and 0.2903 cm (0.01143 inch) for expansion joint). 

• In static tests (table 16), slab number 4 with 3.81-cm (1.5-inch)-diameter FRP dowel had a 

larger RD (0.0738 cm (0.029 inch)) than slab number 5 with 3.81-cm (1.5-inch)-diameter 

steel dowel (0.029 cm (0.011 inch)) where the ratio of RDs was 2.64 (0.029/0.011) 

corresponding to HS25 loading. 

For Specimens Having Crack Formation away from Joint Location (Table 7) 

Slightly larger RD were noted under static tests (table 15) for slab number 2 (2.54-cm (1.0-inch) 

steel dowels) and slab number 3 (1.5-inch) FRP dowels) due to crack formation at dowel edges. 

In addition to higher RD, the load transferred by dowels was less due to that crack formation. 

For Base Material Properties (Table 6) 

Experimental results on RD were sensitive to supporting base stiffness (k). During tests, the base 

property (modulus of subgrade reaction, k) value changed from 11.072 to 22.144 kg/cm3

 (400 to 

800 pci) after 5 million fatigue cycles were applied on slab number 4. RD was expected to 

increase due to the increase in value of subgrade reaction k. 

Joint LTE 

AASHTO characterizes LTE value greater than 70 percent as “very good.”(1) APCA suggests 

that 75 percent of joint effectiveness (E) is sufficient for heavy traffic load, which corresponds to 

60 percent of LTE as defined by AASHTO.(11) 
123

For Specimens (Numbers 1, 4, and 5) Having Proper Crack Formation at Joint Location 

• In static tests, all slabs provided good LTE, which was greater than AASHTO and APCA 

requirements. Slab number 1 (2.54-cm (1.0-inch)-diameter FRP dowels with 15.24-cm 

(6-inch)-c/c spacing) had a greater than 90 percent LTE. Both slab number 4 (3.81-cm 

(1.5-inch)-diameter FRP dowel with 30.48-cm (12-inch)-c/c spacing) and slab number 5 

(3.81-cm (1.5-inch)-diameter steel dowels with 30.48-cm (12-inch)-c/c spacing) had an LTE 

of more than 88 percent. 

• The LTE was found to be 93.79 percent when 1.5 times design load (HS25 loading) was 

applied for slab number 1 (2.54-cm (1.0-inch)-diameter FRP dowel at 15.24-cm (6-inch)-c/c 

spacing) after finishing 1 million fatigue cycles. Later, an increased joint width (increased 

from 0.635 to 1.02 cm (0.25 to 0.4 inch)) after 2 million cycles was considered; the observed 

LTE in slab number 1 reduced from 93.79 percent to 71.57 percent, but it was still higher 

than 60 percent of LTE (corresponding to 75 percent of joint effectiveness, E) (ACPA). 

• In fatigue tests, slab number 4 provided good LTE, greater than 80.5 percent after 5 million 

fatigue load cycles when the base surface and base material under the slab remained in good 

condition. When the base aggregates were crushed and some of the aggregates were pushed 

outside of the slab-base contact area (poor base condition), LTEs were found to decrease to 

about 55 percent, but they were still around 92.1 percent of the 60 percent LTE, which 

corresponds to the ACPA recommended value on joint effectiveness, E, 75 percent. Detailed 

data are shown in figure 43. 

• At 2 million cycles, slab number 4 containing FRP dowels provided slightly lower LTE 

(85.1 percent versus 90.21 percent) than slab number 5 containing steel dowels (table 21). 

With poor base condition (as defined in the previous finding), LTE of the slab with FRP 

dowels over the slab with steel dowels was 50.71 percent versus 90.21 percent. The most 

plausible reason causing the low LTE was poor base condition. It should be noted that the 

modulus of subgrade reaction k changed from 11.072 to 22.144 kg/cm3

 (400 to 800 pci) after 

5 million cycles. 

• Compaction of the base was noted especially under the loaded side of slabs during the tests, 

which could have created slight concave surfaces under the slabs, possibly leading to 

reduction in LTE. It is suggested to check the base property (such as k, modulus of subgrade 

reaction) before and after each fatigue test. 

For Specimens Having Crack Formation away from Joint Location (Table 7) 

Due to the crack formation, LTEs from slab number 2 (2.54-cm (1-inch)-diameter steel dowels 

with 15.24-cm (6-inch) spacing) and slab number 3 (3.81-cm (1.5-inch)-diameter FRP dowels 

with 15.24-cm (6-inch) spacing) were slightly lower than that from slab number 1 in static tests 

(table 18). 
124

Investigation of Pavement Pumping Problem 

• LTEs were observed in cases investigated for simulated pavement pumping problems with 

supporting base removal up to a certain length near the joint (figure 47 and figure 50). LTEs 

were not less than the LTEs obtained from intact base condition (table 20). However, under 

fatigue load cycles, LTE was expected to reduce significantly for specimens without support 

near the joint. 

• The LTE obtained in test case two (30.48 cm (12 inches) base material removal under both 

sides of slabs) was greater than 90 percent at 13.345 kN (3 kips) loading, and, after loading 

exceeded 13.345 kN (3 kips), two joint faces would bear against each other. Thus, case two 

(30.48 cm (12 inches) base removal under both slabs) with unsupported slab areas on both 

sides of the slab was more detrimental than case one (60.96 cm (24 inches) base removal 

under loaded slab). 

Strains on Dowels 

Strain values at the unloaded side of dowels during static tests from slab number 1 and slab 

number 5 were 513.04 and 376.43 microstrains, respectively. Both values were less than those 

from analytical evaluation (ranges from 1,000 to 1,200 microstrains) (appendix C). However, 

strain values are typically not used for LTE calculation. 

CONCLUSIONS FOR FIELD APPLICATIONS AND TEST RESULTS 

Conclusions for FRP Dowels Used for New Highway Pavement Construction 

Effect of Dowel Spacing 

• For dowel groups in pavement joints 2 and 3 that had the same dowel diameter (3.81 cm 

(1.5 inches)), joint 2, with smaller dowel spacing (22.86-cm (9-inches)), had a higher LTE 

(94 percent) than that provided by joint 3, with 30.48-cm (12-inch) dowel spacing 

(81.58 percent). 

• Joint 2, with 3.81-cm (1.5-inch) diameter and 22.86-cm (9-inch) spacing, had smaller RD 

(6.35 × 10-3 cm (0.25 × 10-3 inch)) than joint 3, with same diameter bar and 30.48-cm 

(12-inch) spacing (17.78 × 10-3 cm (0.70 × 10-3 inch)). 

• Joint 2, with 3.81-cm (1.5-inch)-diameter dowels and 22.86-cm (9-inch) spacing, provided a 

15.4-percent increase in LTE in addition to a 64.3-percent reduction in RD over joint 3, with 

3.81-cm (1.5-inch)-diameter dowels and 30.48-cm (12-inch) spacing; refer to table 28. 

• For pavement joints 5 and 6 with 2.54-cm (1.0-inch) dowel diameters, 20.32- and 15.24-cm 

(8.0- and 6.0-inch) dowel spacing, respectively, the LTEs were very close (95 percent and 

94.44 percent). Relative joint deflections were also identical (2.54 × 10-3 cm (1 × 10-3 inch)). 

• For JPCP with 2.54- or 3.81-cm (1.0- or 1.5-inch) FRP dowels, larger dowel spacings of 

30.48 cm (12 inches) (for 2.54-cm (1.0-inch)-diameter dowels) or 20.32 cm (8 inches) (for 
125

2.54-cm (1.0-inch)-diameter dowels) resulted in higher dowel strains compared to those with 

22.86- or 15.24-cm (9- or 6-inch) spacing (for 3.81-cm (1.5-inch) diameter dowels and 

2.54-cm (1.0-inch)-diameter dowels, respectively) under AASHTO Type 3 truck loading. 

o For example, for 2.54-cm (1.5-inch)-diameter FRP dowels (A1 and A2), dowels A2 with 

larger spacing (30.48 cm (12 inches)) had greater strain change (31 microstrain) than 

dowels A1 with 22.86-cm (9-inch) spacing (strain change of 9 microstrain). Similarly, for 

FRP dowels C5 and C6 with the same 2.54-cm (1.0-inch) diameter, the dowel C5 with 

smaller spacing (15.24 cm (6 inches)) showed a small strain change (3 versus 

60 microstrain) compared to dowels C6 with 20.32-cm (8-inch) spacing. 

o Decreasing the spacing by 25 percent (30.48 to 22.86 cm (12 to 9 inches) and 20.32 to 

15.24 cm (8 to 6 inches)) resulted in more dowels sharing the load within the radius of 

relative stiffness (lr, see equation 15), leading to 30 percent or higher strain reductions in 

dowels. 

• For FRP dowels with 2.54-cm (1.0-inch) diameters (C5 and C6), the increase of spacing from 

15.24 to 20.32 cm (6 to 8 inches) had a higher influence on strain value change (3 versus 

60 microstrain) than the increase of spacing from 22.86 to 30.48 cm (9 to 12 inches) for 

dowels (A1 and A2) with 3.81-cm (1.5-inch) diameters (9 versus 31 microstrain). 

• Dowels with different diameters and spacing could be compared with one another based only 

on strain value. Because FRP dowels act as a group, spacing and diameter are both important 

factors for the group action. It should be noted that FRP dowels with smaller diameters 

typically had better mechanical properties per unit area than larger diameter dowels due to 

shear lag effects (refer to chapter 6). 

Effect of Dowel Diameter 

• Both 3.81-cm (1.5-inch)-diameter and 2.54-cm (1.0-inch)-diameter FRP dowel groups with 

spacing varying from 30.48 to 15.24 cm (12 to 6 inches) provided very good LTE (81 percent 

and higher)—they had LTE greater than 60 percent, which corresponds to ACPA’s 

75 percent joint effectiveness (E) value. 

Relative Deflection 

• Currently, there is no requirement or limitation for the RD from AASHTO’s Guide for 

Pavement Structures.

(1) From field tests the maximum RD was 17.78 × 10-3 cm 

(0.70 × 10-3 inch), corresponding to AASHTO Type 3 truck loading, but, for the laboratory 

test, the maximum value was 0.109 cm (43 × 10-3 inch) (table 15) corresponding to HS25 

loading. It should be noted that joint width due to different joint models (contraction versus 

expansion joint models) and thermal variables also affected field LTE values. 
126

Conclusions for FRP Dowels Used for Highway Pavement Rehabilitation 

Pavement rehabilitation was successfully carried out using FRP dowels near the junction of 

Routes 119 and 857, University Avenue, Morgantown, WV. After nearly 7 years of 

rehabilitation, this pavement is performing well without any pavement distress. Strains were 

monitored on this pavement, which is one of the busiest traffic routes in Morgantown, WV. 

• Strains at loaded and unloaded status from FRP dowels (A and B) (28.17 and 

36.24 microstrain) were greater than those from steel dowels (C) (11.49 microstrain), which 

conforms to analytical findings of shorter FRP dowel length required than the length required 

for steel dowels and higher deflection in FRP dowels (refer to figure 108). 

• The strain value ratio from the same gauge at unloaded to loaded status does not represent a 

proper measure of LTE. It is suggested that LTE should be calculated from the pavement 

deflection measurement. 

CONCLUSIONS FOR ANALYTICAL EVALUATION 

Calculations have been carried out for dowel diameters (3.81 and 2.54 cm) (1.5 and 

1.0 inches) for both FRP and steel dowels. The base modulus of subgrade reaction 

k = 11.072 kg/cm3 (400 pci), fc′ = 31.026 MPa (4,500 psi), and other parameters considered 

for calculation are listed in examples 1 through 4. 

Conclusions for 3.81-cm (1.5-inch)-Diameter Dowels with 30.48-cm (12-inch)-c/c Spacing 

Effect of Dowel Material 

• Based on current equations, for dowels with the same spacing, steel dowels provided lower 

values of maximum dowel deflection (y0), dowel shear deflection (δ ), RD (Δ), and bearing 

stress (σb) as compared to FRP dowels. 

• For the same-design spacing (30.48 cm (12 inches)), the maximum bending deflection (y0) of 

FRP dowels was 56 percent more than those from steel dowels (0.00948 versus 0.00606 cm 

(3.731 versus 2.386 milli-inches)). Due to a larger shear deflection, the total RD of FRP 

dowels was 1.95 times the value of RD from steel dowels (0.0237 versus 0.0121 cm 

(9.33 versus 4.78 milli-inches)). 

Effect of Dowel Spacing 

• Current equations to evaluate JPCP response to wheel load do not include dowel material 

properties. The radius of relative stiffness, number of effective dowels, and critical dowel 

load remained identical for FRP and steel dowels for a given spacing. 

o For example, for pavement with 30.48-cm (12-inch)-c/c spacing, FRP and steel dowels 

with fc′ = 31.026 MPa (4,500 psi) and a joint width of 0.635 cm (0.25 inch) had identical 

lr (82.342 cm (32.4180 inches)), number of effective dowels (1.89), and critical dowel 

load (2.161 metric tons (4,763.15 lb)). 
127

• Current equations for evaluating JPCP response to wheel load have smaller dowel spacing 

design results in the same values for the radius of relative stiffness, larger values for the 

number of effective dowels, and lower values for critical dowel load as compared to a larger 

dowel spacing. 

o For example, for pavement with 15.24-cm (6-inch)-c/c spacing, FRP and steel dowels 

with fc′ = 31.026 MPa (4,500 psi) and joint width of 0.635 cm (0.25 inch) had an 

identical lr (82.342 cm (32.4180 inches)), a larger number of effective dowels (3.2238 

versus 1.8895), and a lower critical dowel load (1.266 versus 2.161 metric tons (2,791.76 

versus 4,763.15 lb)) as compared to dowels with 30.48-cm (12-inch)-c/c spacing. 

• Spacings between FRP dowels (3.81-cm (1.5-inch) diameter) less than 17.78 cm (7 inches) 

provided a maximum dowel bending deflection (y0) (0.006 302 cm (2.481 × 10-3 inch)) that 

was close to the value (0.00606 cm (2.386 × 10-3 inch)) provided by steel dowels with 

3.81-cm (1.5-inch) diameter and 30.48-cm (12-inch) spacing (refer to table 33). 

Effect of Joint Width 

• Shear deflection depended on joint width and was significant for FRP dowels. 

• For example, when joint width z = 0.635 cm (0.25 inches) with 30.48-cm (12-inch) dowel 

spacing, shear deflection of the FRP dowels (δ ) was 1.872/9.33 = 20.06 percent of the total 

RD. Shear deflection of the steel dowels with 0.635-cm (0.25-inch) joint width was only 

0.15 percent (0.007/4.78) of its total RD. When joint width was reduced to 0.07938 cm 

(0.03125 inch) (FRP* case in table 33), the shear deflection of FRP dowels was only 

3.30 percent (0.234/7.10) as compared to 20.06 percent with 0.635-cm (0.25-inch) joint 

width (refer to table 33). 

• For same-diameter (3.81-cm (1.5-inch)) FRP dowels, use of the contraction joint model 

greatly reduced the shear effect of dowels. 

o For example, RD for joints with FRP dowel bars were greatly reduced (0.03896 versus 

0.019812 cm (15.34 versus 7.80 milli-inches) with joint width of 0.635 cm (0.25 inch) 

reduced to 0.0794 cm (0.03125 inch). 

Effect of Dowel Length 

• The required FRP length for 3.81-cm (1.5-inch)-diameter dowels was only 64.7 percent 

(11/17) of that of steel dowels with the same diameter. Based on inflexion points (figure 108), 

the minimum total length needed for steel dowels was 43.18 cm (17 inches) (2 by 21.59 cm 

(2 by 8.5 inches)), whereas FRP dowel bars needed 27.94 cm (11 inches) (2 by 13.97 cm 

(2 by 5.5 inches)). 
128

Effect on Bearing Stress 

• For a given set of pavement properties in terms of fc′, thickness, joint width, dowel diameter, 

and spacing, pavement with FRP and steel dowels showed significant differences in 

deflection and bearing stress value. 

• For current analytical models, bearing stress around the dowel-concrete (3.81-cm (1.5-inch) 

diameter) interface is only associated with maximum bending deflection. In order to meet the 

bearing stress limit (25.856 MPa (3,750 psi) in this case), spacings for steel dowels (3.81-cm 

(1.5-inch) diameter) cannot exceed 30.48 cm (12 inches), whereas spacing for FRP dowels 

(3.81-cm (1.5-inch) diameter) should not be more than 17.78 cm (7 inches) (expansion joint) 

or 19.05 cm (7.5 inches) (contraction joint) (refer to table 33). 

• Peak bearing stress at the joint location did not take into account the stiffness match between 

FRP dowel and concrete, which allowed better distribution of bearing stress, leading to 

reduced bearing stress concentration. Theoretical calculations indicated that allowable stress 

was exceeded. However, for 3.81-cm (1.5-inch)-diameter FRP dowel bars with 30.48-cm 

(12-inch)-c/c spacing, the average bearing stress was only 35.4 percent (distance from the 

joint face to the first inflexion point) and 60.98 percent (within 2.54-cm (1-inch) distance 

from the joint face) of the peak bearing stress (table 34 and table 35). 

• Bearing stress (σb) could be reduced by increasing dowel diameter (d), pavement slab 

thickness (h), and concrete strength (fc

′

), or it could be reduced by decreasing dowel spacing 

(b), joint width (z), modulus of subgrade reaction (k), and modulus of dowel support (Κ0). 

Conclusions for 2.54-cm (1.0-inch)-Diameter Dowels with 15.24-cm (6-inch)-c/c Spacing 

Effect of Dowel Material 

• For same-design spacing (15.24 cm (6 inches)), the maximum bending deflection (y0) of FRP 

dowels was 54.03 percent more than those from steel dowels (0.01138 versus 0.007381 cm 

(4.479 versus 2.906 milli-inches)). Due to larger shear deflection, the total RD of FRP 

dowels was 1.96 times the value from steel dowels (0.02903 versus 0.01478 cm (11.43 

versus 5.82 milli-inches)). 

Effect of Dowel Spacing 

• Trends of the effect of dowel spacing were found to be similar to those of 3.81-cm 

(1.5-inch)-diameter FRP dowel bars. 

• Spacings between FRP dowels (2.54-cm (1.0-inch) diameter) less than 8.89 cm (3.5 inches) 

provided a dowel maximum bending deflection (y0) (7.132 × 10-3 cm (2.808 × 10-3 inch)) that 

was close to the value (7.381 × 10-3 cm (2.906 × 10-3 inch) of steel dowels (3.81-cm (1.5-inch) 

diameter) with 15.24-cm (6-inch) spacing (refer to table 36). 
129

Effect of Joint Width 

• Shear deflection depended on joint width and was significant for FRP dowels. 

o For example, when joint width z = 0.635 cm (0.25 inch) with 15.24-cm (6-inch) dowel 

spacing, shear deflection of FRP dowels (δ ) was 2.468/11.43 = 21.59 percent of the total 

RD. Shear deflection of steel dowels with 0.635-cm (0.25-inch) joint width was only 

0.15 percent (0.009/5.82) of its total RD. When joint width was reduced to 0.07938 cm 

(0.03125 inches) (FRP* case in table 32), the shear deflection of FRP dowels was only 

3.70 percent (0.309/8.35) as compared to 21.59 percent (refer to table 33). 

• For same-diameter (2.54-cm (1.0-inch)) FRP dowels, use of the contraction joint model 

greatly reduced the shear effect of dowels. 

o For example, RD for joints with FRP dowel bars were greatly reduced (0.0290 versus 

0.0212 cm (11.43 versus 8.35 milli-inches)) with joint width of 0.635 cm (0.25 inch) 

reduced to 0.0794 cm (0.03125 inch). 

Effect of Dowel Length 

• The required length of 2.54-cm (1.0-inch)-diameter FRP dowels was only 69.23 percent 

(9/13) of the required length of steel dowels with the same diameter. Based on inflexion 

points (figure 109), the minimum total length for steel dowel was 33.02 cm (13 inches) 

(2 × 16.51 cm (2 × 6.5 inches)), whereas, for FRP dowels, the minimum length was 22.86 cm 

(9 inches) (2 × 11.43 cm (2 × 4.5 inches)). 

Effect on Bearing Stress 

• In order to meet the bearing stress limit (31.026 MPa (4,500 psi) in this case), spacings for 

steel dowels (2.54-cm (1.0-inch) diameter) should be limited to 30.48 cm (12 inches), 

whereas spacing for FRP dowels (2.54-cm (1.0-inch) diameter) should not be more than 

8.89 cm (3.5 inches) (expansion joint) or 10.16 cm (4.0 inches) (contraction joint) (table 36). 

• For 2.54-cm (1.0-inch)-diameter FRP dowel bars with 15.24-cm (6-inch)-c/c spacing, the 

average bearing stress was only 34.94 percent (distance from joint face to the first reflection 

point) and 50.44 percent (within 2.54 cm (1 inch) distance from joint face) of the peak 

bearing stress (table 37 and table 38). Hence, based on stress redistribution, peak bearing 

stress did not appear to have damaged the concrete surface. 

GENERAL CONCLUSIONS FROM THIS RESEARCH 

1. In this research, FRP dowels were found to be good alternatives to traditional steel dowels 

for transferring joint loads in JPCP pavements. Joints with FRP dowels provided adequate 

LTE, exceeding the values recommended by AASHTO (75 percent) and ACPA (60 percent) 

in both laboratory and field tests. 
130

2. FRP dowel-concrete interfaces in slabs number 1 and 4 were found to be in excellent 

condition after 5 million HS25 load cycles with no visible damage, microcracks, or 

separation between FRP dowels and surrounding concrete (refer to figure 36 and figure 44). 

3. The stiffness match between FRP dowels and concrete led to comparable FRP dowel flexing 

under joint loads, leading to shorter FRP dowel length. The required length of FRP dowels 

with 3.81-cm (1.5-inch) diameter was 64.7 percent of that for steel dowels with the same 

diameter. The required length of FRP dowels with a 2.54-cm (1.0-inch) diameter was 

69.23 percent of that for steel dowels with the same diameter. 

4. Under the static loading test, slabs with smaller-diameter FRP dowels and smaller spacing 

provided lower RD than FRP dowels with larger diameter and spacing. During fatigue load 

cycles up to 5 million, RD from slab number 1 with the smaller diameter and spacing of FRP 

dowels appeared to increase (0.3256 to 2.0396 cm (0.0128 to 0.0803 inches) from 2 to 

5 million cycles with a joint width of 1.016 cm (0.4 inches)), whereas RD from slab number 

4 with a larger diameter and spacing of FRP dowels appeared to decrease 32 percent (0.0635 

to 0.0432 cm (0.025 to 0.017 inches) from 2 to 5 million cycles with a joint width of 

0.0635 cm (0.25 inches). 

5. The LTE from slabs with FRP dowels of smaller diameter and spacing (2.54 cm (1 inch) and 

15.24 cm (6 inches)) was found to be sufficient (71.57 percent, when an increased joint width 

of 1.016 cm (0.4 inch) and higher loading of 1.5 × HS25 were considered) after 5 million 

load cycles as per AASHTO (70 percent of LTE) and ACPA (75 percent of E or 60 percent 

of LTE) suggested values. When a good base condition was provided during 5 million 

loading cycles, slabs with FRP dowels having 3.81-cm (1.5-inch) diameter and 30.48-cm 

(12-inch) spacing provided good LTE (greater than 80.5 percent). However, with a poor base 

condition (aggregate movement leading to a concave surface under the slab), the LTE was 

reduced to 55.26 percent (which is 92.1 percent of 60 percent LTE, corresponding to the 

ACPA recommended value on joint effectiveness, E = 75 percent). Hence, it is very 

important to have the proper slab casting procedure and compacted aggregate base. 

6. LTE affected the slab integrity and slab stresses, whereas RD affected ride comfort and 

impact on the slab at joints. It was important to consider both RD and LTE when the 

performance of JPCP was evaluated. For example, at 5 million cycles, slab number 4 with 

3.81-cm (1.5-inch)-diameter FRP dowels spaced at 30.48 cm (12 inches) c/c had 

55.26 percent LTE, but its RD (0.043 cm (0.017 inch)) was less than that of slab number 1 

with 2.54-cm (1.0-inch)-diameter FRP dowels and 71.6 percent LTE spaced at 15.24 cm 

(6 inches) c/c (2.04 cm (0.0803 inch)). 

7. FRP dowels can be used as effective alternatives for construction and rehabilitation of JPCP 

under highway traffic with advantages of corrosion resistance and decreased maintenance. 

Long-term performance evaluation of JPCP with FRP dowels is being continued by the 

Constructed Facilities Center, WVU. 
131

RECOMMENDATIONS 

1. Test more laboratory specimens for establishing possible ranges of LTE and RD values for 

different diameter, spacing, and length of dowel. 

2. Further investigate crack formation location by using increased FRP dowel length, including 

deflection shapes. 

3. Evaluate actual dowel bar deflected shapes in the slab under different base removal 

conditions. 

4. Evaluate the effect of peak bearing stress and average bearing stress on dowel/concrete 

interface. 

5. Evaluate the effect of fiber volume fraction on dowel behavior, including shear properties 

that affect joint LTE and RD. 

6. Evaluate the durability of the FRP dowel. 

7. Utilize finite element modeling to envision stress field in the concrete pavement. 

8. Continue long-term field monitoring. 

133

APPENDIX A. TEST OF TIMBER TIE WITH FRP DOWELS 

Before evaluating FRP dowels in concrete slabs joints, pilot tests were carried out using 

rectangular timber beams. A long timber beam was cut into two halves and drilled with 4.45-cm 

(1.75-inch)-diameter holes to simulate dowel sockets in a slab. Dowel sockets facilitated 

placement of instrumented dowels inside the timber beams. Load tests were conducted by 

turning dowels at 45-degree angles to measure dowel strains from longitudinal and transverse 

gauges (figure 110 to figure 112). 

Four cases were evaluated based on loading position and timber depth (corresponding to 

positioning of the timber beam surface on the base). Test setup of each case is shown in 

figure 111. 

Figure 110. Photo. Lab test of timber tie with FRP dowel bar as the load transfer device. 
134

1 inch = 2.54 cm 

Figure 111. Diagram. Four timber test cases. 

Figure 112. Diagram. Rosette strain gauges. 
135

Table 40. Strains during loading and unloading on case I-A. 

Loading Unloading 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

0 0 0 20 1,627 7,836 

1 64 576 19 1,610 7,797 

2 229 1,707 18 1,580 7,752 

3 377 2,585 17 1,554 7,707 

4 493 3,182 16 1,527 7,662 

5 624 3,848 15 1,498 7,609 

6 725 4,389 14 1,467 7,562 

7 804 4,770 13 1,432 7,522 

8 871 5,118 12 1,391 7,420 

9 933 5,415 11 1,346 7,365 

10 1,021 5,668 10 1,292 7,167 

11 1,105 5,962 9 1,226 7,032 

12 1,166 6,188 8 1,135 6,982 

13 1,223 6,384 7 1,032 6,670 

14 1,285 6,584 6 940 6,495 

15 1,347 6,844 5 790 5,957 

16 1,393 7,011 4 674 5,610 

17 1,451 7,204 3 560 4,971 

18 1,515 7,409 2 605 3,987 

19 1,564 7,599 1 171 2,370 

20 1,627 7,781 0 0 0 

1 kip = 4.448 kN 
136

Table 41. Strains during loading and unloading on case I-B. 

Loading Unloading 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

0 0 0 20 1,357 5,920 

1 59 49 16 1,332 5,976 

2 220 592 12 1,302 5,931 

3 511 1,787 8 1,265 5,863 

4 734 3,238 4 1,081 5,066 

5 799 3,419 0 0 136 

6 899 3,872 

7 908 4,040 

8 1,012 4,325 

9 1,040 4,559 

10 1,067 4,740 

11 1,106 4,901 

12 1,137 5,044 

13 1,144 5,091 

14 1,152 5,119 

15 1,186 5,241 

16 1,206 5,339 

17 1,251 5,473 

18 1,277 5,610 

19 1,310 5,746 

20 1,357 5,920 

1 kip = 4.448 kN 

0

5

10

15

20

25

0 2000 4000 6000 8000 10000

Strain (Microstrain)

Load (Kips)

Loaded

unloaded

1 kip = 4.448 kN 

Figure 113. Chart. Plot for longitudinal strain gauges (case I-A and case I-B). 
137

Table 42. Strains during loading and unloading on case II-A. 

Loading Unloading 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

Load 

(kips) 

Transverse 

Gauge 

Longitudinal 

Gauge 

0 0 0 20 1 7 

2 1 8 16 1 6 

4 1 7 12 1 6 

6 1 7 8 1 6 

8 1 7 4 1 6 

10 1 7 0 0 0 

12 1 7 

14 1 7 

16 1 6 

18 1 7 

20 1 7 

1 kip = 4.448 kN 
138

Table 43. Deflections of timber tie on case I-A. 

Load (kips) 

Dial Gauge Reading 

at Loaded End 

(inch) 

Deflection at x1 

(inch) 

Dial Gauge 

Reading at 

Unloaded End 

(inch) 

Deflection at x2 

(inch) 

0 0.469 0.000 0.515 0.000 

1 0.402 0.067 0.490 0.025 

2 0.335 0.134 0.465 0.050 

3 0.238 0.231 0.468 0.047 

4 0.170 0.299 0.467 0.048 

5 0.130 0.339 0.466 0.049 

6 0.080 0.389 0.465 0.050 

7 0.048 0.421 0.465 0.050 

8 0.020 0.449 0.465 0.050 

9 -0.190 0.659 0.465 0.050 

10 -0.170 0.639 0.465 0.050 

11 -0.160 0.629 0.465 0.050 

12 -0.150 0.619 0.465 0.050 

13 -0.162 0.631 0.465 0.050 

14 -0.176 0.645 0.466 0.049 

15 -0.197 0.666 0.466 0.049 

16 -0.215 0.684 0.467 0.048 

17 -0.229 0.698 0.467 0.048 

18 -0.247 0.716 0.468 0.047 

19 -0.262 0.731 0.468 0.047 

20 -0.275 0.744 0.469 0.046 

1 kip = 4.448 kN 

1 inch = 2.54 cm 
139

Table 44. Deflections of timber tie on case I-B. 

Load (kips) 

Dial Gauge 

Reading at 

Loaded End 

(inch) 

Deflection at 

y1 (inch) 

Dial Gauge 

Reading at 

Unloaded End 

(inch) 

Deflection at 

y2 (inch) 

0 0.915 0.000 0.525 0.000 

1 0.870 0.045 0.501 0.024 

2 0.825 0.090 — — 

3 0.660 0.255 — — 

4 0.575 0.340 0.406 0.119 

5 0.515 0.400 — — 

6 0.462 0.453 — — 

7 0.430 0.485 — — 

8 0.390 0.525 0.397 0.128 

9 0.365 0.550 — — 

10 0.331 0.584 — — 

11 0.300 0.615 — — 

12 0.272 0.643 0.388 0.137 

13 0.250 0.665 — — 

14 0.228 0.687 — — 

15 0.202 0.713 — — 

16 0.185 0.730 0.383 0.142 

17 0.165 0.750 — — 

18 0.140 0.775 — — 

19 0.123 0.792 — — 

20 0.090 0.825 0.382 0.143 

— No data at corresponding loads. 

1 kip = 4.448 kN 

1 inch = 2.54 cm 
140

0

5

10

15

20

25

0.000 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800

Load (kips)

Loaded X1

unloaded x2

1 kip = 4.448 kN 

Figure 114. Chart. Load versus deflection (inches) of timber tie for case I-A. 

0

5

10

15

20

25

0.000 0.200 0.400 0.600 0.800 1.000

Load (kips)

Loaded Y1

unloadedy2

1 kip = 4.448 kN 

Figure 115. Chart. Load deflection (arm with regular gauge) for case I-B. 

Joint Effectiveness from Case I-A and Case I-B Under 20 kips Loading 

Case I-A 

%15.12%100

)046.0744.0(

2 046.02

=×

+

× = ×

Deflection SidesBothofTotal

Deflection Unloadedat Side

(68) 

Case I-B 

100% 29.55%

.0( 825 .0 143)

2 .02 143

=×

+

× = ×

DeflectionTotalof BothSides

DeflectionatUnloaded Side

 (69) 

In this preliminary test, joint effectiveness obtained in timber with 3.81-cm (1.5-inch) FRP 

dowels was low. This was due to several factors, such as the low stiffness of timber material and 

the larger hole diameter (4.45 cm (1.75 inches)) for accommodating 3.81-cm (1.5-inch)-diameter 

FRP dowels. 
141

APPENDIX B. ANALYTICAL EVALUATION OF EFFECT OF FRP DOWEL SHEAR 

MODULUS ON PAVEMENT RD 

Analytical evaluation was conducted to find the effect of a dowel shear modulus on pavement 

RD. Parameters used for calculation are listed below. Detailed data are shown in tables 44 and 45, 

and figure 16 and figure 17: 

• FRP dowel. 

o Diameter, d = 3.81 and 2.54 cm (1.5 and 1.0 inches). 

o Length, L = 45.72 cm (18 inches). 

o Spacing between each dowel, b = 15.24, 30.32, 25.4, and 30.48 cm (6, 8, 10, and 

12 inches). 

o Modulus of elasticity, Ed = 3.79 × 104

 MPa (5.5 × 106 psi) for 3.81-cm (1.5-inch)- 

diameter dowel and Ed = 4.14 × 104 MPa (6.0 × 106 psi) for 2.54-cm (1.0-inch) diameter. 

o Shear modulus of dowel, low Gd = 0.28 × 104 MPa (0.4 × 106 psi), and high 

Gd = 5.17 × 104

 MPa (0.75x106 psi). 

o Moment of inertia of the dowel, 

Id 0.248505

64

4

= × = π d (in4).

 (70) 

o Cross-sectional area of dowel, A = 4.496 cm2

 (1.77 inches2). 

• Concrete pavement. 

o Compressive strength, fc′ = 31.026 MPa (4,500 psi). 

o Modulus of elasticity, 

Ec = 

5.0 57000 )'( c × f 

(= 3823676.2 psi = 3.82 × 106 psi)

= 2.64 × 104 MPa. (71) 

o Pavement thickness, h = 27.94 cm (11 inches). 

o Joint width, z = 0.635 cm (0.25 inch). 

o Poisson’s ratio of concrete, ν = 0.2. 

o Modulus of dowel support, K0 = 4.15 × 104

 kg/cm3 (1.5 million pci). 
142

• Base. 

o Modulus of subgrade reaction, k = 11.072 kg/cm3

 (400 pci). 

• Load. 

o Design Traffic Load HS25, applied wheel load Pw = 9.071 metric tons (20,000 lb). 

o Design load transfer by joint = 45 percent. 

o Pt = load transferred across the joint 

= 45 Pw × .0

(= 9000 lb) 

 = 4.082 metric tons. (72)

Table 45. RD with low dowel shear modulus (Gd = 2.758 × 103 MPa (0.4 × 106 psi)). 

Diameter of 

Dowel 

(inches) 

Bending 

Deflection 

(inch) 

Bending 

Deflection 

(inch) 

Shear 

Deflection 

(inch) 

Total Relative 

Deflection 

(inch) 

1.0 0.0045 0.0045 0.0025 0.0114 

1.5 0.0022 0.0022 0.0011 0.0055 

1.0 0.0057 0.0057 0.0031 0.0145 

1.5 0.0028 0.0028 0.0014 0.0070 

1.0 0.0067 0.0067 0.0037 0.0171 

1.5 0.0033 0.0033 0.0016 0.0082 

1.0 0.0076 0.0076 0.0042 0.0195 

1.5 0.0037 0.0037 0.0019 0.0093 

1 inch = 2.57 cm 

Table 46. RD with high dowel shear modulus (Gd = 5.17 × 103

 MPa (0.75 × 106 psi)). 

Diameter of 

Dowel 

 (inches) 

Bending 

Deflection 

(inch) 

Bending 

Deflection 

(inch) 

Shear 

Deflection 

 (inch) 

Total Relative 

Deflection 

(inch) 

1.0 0.0045 0.0045 0.0013 0.0103 

1.5 0.0022 0.0022 0.0006 0.0050 

1.0 0.0057 0.0057 0.0017 0.0131 

1.5 0.0028 0.0028 0.0007 0.0063 

1.0 0.0067 0.0067 0.0020 0.0154 

1.5 0.0033 0.0033 0.0009 0.0074 

1.0 0.0076 0.0076 0.0022 0.0175 

1.5 0.0037 0.0037 0.0010 0.0085 

1 inch = 2.57 cm 
143

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

6 in. c/c 

Dowel A

6 in. c/c

Dowel B

 8 in. c/c

Dowel A

8 in. c/c

Dowel B

10 in. c/c

Dowel A

10 in. c/c

Dowel B

12 in. c/c

Dowel A

12 in. c/c

Dowel B

Deflections. (inches)

1 inch = 2.54 cm 

Figure 116. Graph. Components of RD for dowel types A (2.54-cm (1.0-inch) diameter) and 

B (3.81-cm (1.5-inch) diameter), with k = 11.072 kg/cm3 (400 pci), fc' = 31.026 MPa 

(4,500 psi), joint width = 0.635 cm (0.25 inch), and Gd = 2.8 × 103

 MPa (0.4 × 106 psi). 

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

6 in. c/c 

Dowel A

6 in. c/c

Dowel B

 8 in. c/c

Dowel A

8 in. c/c

Dowel B

10 in. c/c

Dowel A

10 in. c/c

Dowel B

12 in. c/c

Dowel A

12 in. c/c

Dowel B

Deflections. (inches)

1 inch = 2.54 cm 

Figure 117. Graph. Components of RD for dowel types A (2.54-cm (1.0-inch) diameter) and 

B (3.81-cm (1.5-inch) diameter), with k = 11.072 kg/cm3

 (400 pci), fc' = 31.026 MPa 

(4,500 psi), joint width = 0.635 cm (0.25 inches), and Gd = 5.17 × 103

 MPa (0.75 × 106 psi). 

145

APPENDIX C. FIBER BURNOUT TESTS FOR DETERMINING FIBER WEIGHT 

FRACTION AND FIBER VOLUME FRACTION FOR FRP DOWELS 

Burnout tests were conducted to determine the FWF and FVF for both 2.54-cm (1.0-inch)- 

diameter FRP dowels and 3.81-cm (1.5-inch)-diameter FRP dowel. Details are listed in table 46 

and table 47. 

Table 47. FWF and FVF for FRP dowel with 2.54-cm (1.0-inch) diameter. 

Sample 

FRP Sample 

Total Resin 

Weight 

(g) 

E-glass Fiber 

Fiber 

Weight 

Fraction 

(FWF, 

percent) 

Fiber 

Volume 

Fraction 

(FVF, 

percent) 

Weight 

(g) 

Volume 

(inches3

) 

Weight 

(g) 

Volume 

(inches3)

A1 23.00 0.7399 6.38 16.62 0.3977 72.26 53.75

A2 23.12 0.7383 6.40 16.72 0.4001 72.31 54.20

Average 72.29 53.98

Note: E-glass fiber volume was calculated by using E-glass fiber weight divided by its density (2.55 g/cm3), a 

converter factor 1 cm3 = 0.06102374 in3

 was used for the calculations. 

1 inch = 2.54 cm 

Table 48. FWF and FVF for FRP dowel with 3.81-cm (1.5-inch) diameter. 

Sample 

FRP Sample 

Total Resin 

Weight 

(g) 

E-glass Fiber 

Fiber 

Weight 

Fraction 

(FWF, 

percent) 

Fiber 

Volume 

Fraction 

(FVF, 

percent) 

Weight 

(g) 

Volume 

(in3

) 

Weight 

(g) 

Volume 

(in3) 

B1 54.81 1.7737 16.736 38.074 0.9111 69.47 51.37

B2 54.19 1.7576 16.546 37.644 0.9009 69.47 51.25

Average 69.47 51.31

Note: E-glass fiber volume was calculated by using E-glass fiber weight divided by its density (2.55 g/cm3 

(0.092 lb/in3

)); a conversion factor of 1 cm3 = 0.06102374 in3 was used for the calculations. 

1 inch = 2.54 cm 

147

REFERENCES 

1. American Association of State Highway and Transportation Officials (AASHTO), 

AASHTO Guide for Design of Pavement Structures. AASHTO. Washington, DC, 1993. 

2. Friberg, B.F., “Design of Dowels in Transverse Joints of Concrete Pavements,” 

Transactions, American Society of Civil Engineers, Vol. 105, No. 2081, 1940. 

3. Vijay, P.V. and GangaRao, H.V.S., Development of Fiber Reinforced Plastics for 

Highway Application: Aging Behavior of Concrete Beams Reinforced with GFRP Bars. 

CFC-WVU Report No. 99-265 (WVDOH RP #T-699-FRP1), 1999. 

4. Washington State Department of Transportation (WSDOT), Pavement Guide, May 2005. 

5. VanWijk, A.J., Larradale J., Lovell, C.W., and Chen W.F., “Pumping Prediction Model 

for Highway Concrete Pavements,” Journal of Transportation Engineering, Vol. 115, 

Issue 2, pp. 161–175, 1989. 

6. Brown, V. L. and Bartholomew, C.L. “FRP Dowel Bars in Reinforced Concrete 

Pavements,” Proceedings of the International Symposium on FRP Reinforcement for 

Concrete Structures, ACI, 1993. 

7. Ahmed, S., Scott, M., “Using Fiber-Reinforced Polymer Load Transfer Devices in 

Jointed Concrete Pavements,” 7th International Conference on Concrete Pavements—

Orlando, FL, September 9–13, 2001. 

8. Eddie, D., Shalaby, A., and Rizkalla, S., “Glass Fiber-Reinforced Polymer Dowels for 

Concrete Pavements,” American Concrete Institute Structural Journal, Vol. 98, No. 2, 

2001. 

9. Porter, M.L., Guinn, Jr., R.J., Lundy, A.L., Davis, D.D., and Rhner J.G., “Investigation of 

Glass Fiber Composite Dowel Bars For Highway Pavement Slabs,” Project No. TR-408, 

Iowa State University, 2001. 

10. American Standard for Testing and Materials (ASTM), “Annual Book of ASTM 

Standards,” Concrete and Aggregates, Vol. 0402. 

11. American Concrete Pavement Association (ACPA). Design and Construction of Joints 

for Concrete Highways. ACPA, Skokie, Illinois, 1991. 

12. American Association of State Highway and Transportation Officials (AASHTO), 

Standard Specifications for Highway Bridges. 15th ed. AASHTO. Washington, DC, 1992. 

13. Timoshenko, S. and Lessels, J.M. Applied Elasticity. Westinghouse Technical Night 

School Press, Pittsburgh, PA, 1925. 

14. Friberg, B. F. “Load and Deflection Characteristics of Dowels in Transverse Joints of 

Concrete Pavements.” Proceedings of Highways Research Board No. 18. National 

Research Council. Washington, DC, pp. 140–154, 1938. 

15. Yoder, E.J. and Witczak, M.W. Principles of Pavement Design, 2nd ed. John Wiley & 

Sons, Inc., New York, NY, 1975. 
148

16. Albertson, M.D. “Fiber Composite and Steel Pavement Dowels.” Master’s Thesis. Iowa 

State University, 1992. 

17. Westergaard, H.M. “Computation of Stresses in Concrete Roads.” Proceedings, 5th

Annual Meeting of the Highway Research Board. Washington, DC, 1925. 

18. Tabatabaie, A.M., Barenburg, E.J., and Smith, R.E. “Longitudinal Joint Systems in 

Slipformed Rigid Pavements.” Vol. II-Analysis of Load Transfer Systems for Concrete 

Pavements, Report No. DOT/FAA.RD-79/4, Federal Aviation Administration, 1979. 

19. Porter, M.L., Guinn, Jr., R.J. Assessment of Dowel Bar Research. Iowa DOT Project HR1080, Center for Transportation Research and Education, Iowa State University, 2002. 

20. ACI Committee 325. “Structural Design Considerations for Pavement Joints.” ACI 

Journal, Vol. 53, July, pp. 1–29, 1956. 

HRDI-12/09-09(400)E Recycled

Recyclable