U.S. Department 

of Transportation

Federal Aviation 

Administration

Advisory 

Circular

Subject: HANDBOOK FOR IDENTIFICATION 

OF ALKALI-SILICA REACTIVITY IN AIRFIELD 

PAVEMENTS 

Date: 2/2/04

Initiated by: AAS-100 

AC No: 150/5380-8

Change: 

 

1. PURPOSE. This Advisory Circular (AC) 

provides guidance on understanding, identifying, 

preventing, and mitigating alkali-silica reactivity 

(ASR) in fresh and hardened Portland cement 

concrete airfield pavements. 

2. BACKGROUND. The Federal Aviation 

Administration (FAA) conducted a study on the 

impact of ASR distress on airport runways and 

taxiways in response to Section 743 of the 

Wendall H. Ford Aviation Investment and 

Reform Act for the 21st Century (P.L. 106-181). 

The study involved a determination of ASR 

distress based on in-the-field inspections followed 

by petrographic analysis and other techniques. 

The study confirmed that ASR distress can 

negatively impact the long-term performance of 

airfield pavements. 

This handbook was developed as an integral part 

of the study. It was prepared by the Texas 

Transportation Institute, Texas A&M University, 

through a cooperative agreement between the FAA 

and the National Safe Skies Alliance. 

3. APPLICATION. The handbook provides 

decisionmakers with a framework for the definite 

identification of ASR in airfield pavements. It 

summarizes ways to prevent and mitigate these 

effects, including using lithium. It also discusses a 

new rapid test method that could be routinely 

applied during construction. 

The FAA recommends the information and 

procedures contained in the handbook for use 

during the engineering and design phase of paving 

projects. The handbook is included in this AC as 

Appendix 1. 

4. RELATED READING MATERIAL. 

AC 150/5380-6, Guidelines and Procedures for 

Maintenance of Airport Pavements, provides 

further guidance and technical information for 

identifying distresses in airfield pavements. 

5. ONLINE AVAILABILITY. To view and 

download this AC, visit the FAA Web site at 

http://www.faa.gov/arp/150acs.cfm. 

DAVID L. BENNETT 

Director, Office of Airport Safety and Standards 

 

2/2/04 AC 150/5380-8 

Appendix 1 

i

APPENDIX 1—HANDBOOK FOR IDENTIFICATION OF 

ALKALI-SILICA REACTIVITY IN AIRFIELD PAVEMENT 

Map Cracking Due to Alkali-Silica Reactivity (ASR) in an Airfield Pavement 

Shondeep L. Sarkar, Ph.D., P.E. 

Research Scientist 

Anal Kanti Mukhopadhyay, Ph.D. 

Research Associate 

Dan G. Zollinger, Ph.D., P.E. 

Associate Research Engineer 

Lim Seungwook 

Graduate Research Assistant 

Chang-Seon Shon 

Graduate Research Assistant

Texas Transportation Institute 

Texas A&M University 

College Station, Texas 77843-3135 
AC 150/5380-8 2/2/04 

Appendix 1 

 

ii

DISCLAIMER 

The contents of this handbook reflect the views of the authors, who are responsible for 

the facts and accuracy of the data presented herein. The contents do not necessarily 

reflect the official view or policies of the sponsors or Texas Transportation Institute. 

This handbook does not constitute a standard, specification, or regulation. 
2/2/04 AC 150/5380-8 

 Appendix 1 

iii

FOREWORD 

This handbook has been prepared for airfield engineers and other personnel associated 

with maintenance of airfield pavements. Alkali-silica reactivity (ASR) continues to be a 

detriment to the long-term performance of airfield pavements. Deleterious reaction 

between alkali and reactive aggregate in concrete causes expansion and subsequent 

cracking in pavements. However, damage due to ASR is often difficult to differentiate 

from damage caused by other deleterious mechanisms. The objective of this handbook is 

to provide step-by-step guidance on how to identify ASR in airfield pavements based on 

field inspection and laboratory investigation, and then perform ASR distress rating. Total 

reliance on field observation for identification of ASR is not recommended. Laboratory 

investigation, particularly petrography of core samples, needs to be performed to 

precisely identify ASR and to assess the extent of damage caused by ASR. This 

handbook essentially consists of a framework for definite identification of ASR and 

ASR-induced damage in airfield concrete pavements. 

The use of a special dye can often help to indicate the possible existence of ASR but must 

not be accepted as a decision-making tool for assessing damage caused by ASR. 

Following identification of ASR and evaluation of the degree of distress, it is then 

necessary to consider mitigation and preventive measures. These are summarized in 

Chapter 5. 

A new rapid method for testing the reactivity of as-received aggregates from different 

sources, developed at the Texas Transportation Institute, Texas A&M University, is also 

described in this handbook. A brief description of this new rapid method is given in 

Chapter 8. 

2/2/04 AC 150/5380-8 

 Appendix 1 

v

Table of Contents 

Chapter 1: Understanding Alkali-Silica Reactivity.................................................... 1-1 

1.1 Definition .................................................................................................... 1-1 

1.2 Essential parameters for ASR ..................................................................... 1-1 

1.3 Mechanism of ASR..................................................................................... 1-5 

 

Chapter 2: Field Diagnosis of ASR............................................................................... 2-1 

2.1 Background information ............................................................................. 2-1 

2.2 Visual manifestation of ASR in airfield pavements ................................... 2-1 

2.3 Structural evidence of expansion due to ASR ............................................ 2-7 

2.4 Distinction between ASR distress features and other type of distress 

 features in airfield pavements ..................................................................... 2-9 

2.5 Application of dyes to detect ASR gel in the field ................................... 2-13 

2.6 Selection of coring locations for further laboratory investigation............ 2-14 

2.7 Summary................................................................................................... 2-17 

Chapter 3: Laboratory Investigations ......................................................................... 3-1 

3.1 Use of dye .................................................................................................. 3-1 

3.2 Optical microscopic techniques to identify ASR ....................................... 3-2 

3.3 Scanning electron microscopy/energy dispersive X-ray analysis............... 3-7 

 

Chapter 4: ASR Distress Analysis in Airfield Pavements.......................................... 4-1 

4.1 ASR condition survey................................................................................. 4-1 

4.2 Scoring of ASR distress.............................................................................. 4-3 

4.3 Detailed explanation of the survey sheet .................................................... 4-9 

 

Chapter 5: Mitigation and Prevention of ASR............................................................ 5-1 

5.1 Common preventive measures for ASR ..................................................... 5-1 

5.2 Lithium use in new concrete....................................................................... 5-2

5.3 Mitigation of ASR in existing concrete ...................................................... 5-2 

Chapter 6: References and Further Reading .............................................................. 6-1 

Chapter 7: Test Methods for ASR................................................................................ 7-1 

Chapter 8: Dilatometer ⎯ A Rapid Method for Testing the Reactivity 

of As-Received Aggregates............................................................................................ 8-1 

8.1 Introduction.................................................................................................8–1 

8.2 Experimental...............................................................................................8–2 

 Test Device. ................................................................................................8–2 

 Test Procedure. ...........................................................................................8–4 

8.3 Test Results and Discussion........................................................................8–6 

 Expansion-Age Relationship. .....................................................................8–6 

 Effect of Lithium Nitrate (LiNO3). ...........................................................8–10 
AC 150/5380-8 2/2/04 

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vi

 Effect of Calcium Hydroxide, Ca(OH)2....................................................8–11 

 Repeatability. ............................................................................................8–11 

8.4 Conclusions...............................................................................................8–12 

 Advantages of this Method .......................................................................8–12 

8.5 References.................................................................................................8–14 
2/2/04 AC 150/5380-8 

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vii 

List of Figures 

Figure 1-1. Non-reactive quartz.................................................................................. 1-2 

Figure 1-2. Reactive or strained quartz exhibits dark (A) and light bands (B) within a 

single grain............................................................................................... 1-3 

Figure 1-3. Photomicrograph of a very fine grained (cryptocrystalline) chalcedony 

aggregate in concrete.. ............................................................................. 1-3 

Figure 1-4. Attack of alkali solution on silica lattice.................................................. 1-6 

Figure 2-1. Laddering (→) along a joint due to ASR................................................. 2-2 

Figure 2-2. A close-up view of laddering (→) ........................................................... 2-2 

Figure 2-3. Only a few map cracks (→) ..................................................................... 2-3 

Figure 2-4. Widespread map cracking (→) ................................................................ 2-3 

Figure 2-5. Severe map cracking................................................................................ 2-4 

Figure 2-6. Aggregate pop-out (→)............................................................................ 2-4 

Figure 2-7. Several aggregate particles (A) have been dislodged (→) along with some 

neighboring paste..................................................................................... 2-5 

Figure 2-8. An open internal crack (→) in an ASR-affected aggregate particle (A) . 2-5 

Figure 2-9. Gel exudation through cracks .................................................................. 2-6 

Figure 2-10. Gel exudation (→) through cracks........................................................... 2-6 

Figure 2-11. Joint compression due (→) to slab movement......................................... 2-7 

Figure 2-12. Heaving (→) of an asphalt shoulder due to movement of adjoining 

concrete slab affected by ASR................................................................. 2-7 

Figure 2-13. Misalignment of joint caused by slab movement .................................... 2-8 

Figure 2-14. Heaving of a slab relative to another ....................................................... 2-8 

Figure 2-15. D-cracking (→) in an airfield pavement................................................ 2-10 

Figure 2-16. Corner break (→) in an airfield pavement............................................. 2-11 

Figure 2-17. Corner spall in another airfield pavement.............................................. 2-11 

Figure 2-18. Longitudinal joint spall (→) .................................................................. 2-12 

Figure 2-19. Longitudinal cracks (→) in an airfield pavement .................................. 2-12 

Figure 2-20. Cracks (→) in the central part of a pavement section............................ 2-15

Figure 2-21. Different cracking pattern (→) near the joint of the same pavement 

 section .................................................................................................... 2-15 

Figure 2-22. Full-depth cores from sections of an airfield pavement sharing different 

distress features...................................................................................... 2-16 

Figure 3-1. A slice of a concrete core collected from an airfield pavement under plain 

light .......................................................................................................... 3-1 

Figure 3-2. The same section after dye treatment when viewed under UV light shows 

ASR gel along cracks and around aggregate periphery (→) ................... 3-2 

Figure 3-3. Reaction rim (→) around an aggregate (A) particle due to ASR ............ 3-3 

Figure 3-4. Peripheral discoloration (→) of an opaline limestone aggregate 

 (A) particle............................................................................................... 3-4 

Figure 3-5. A severely cracked opaline siliceous fine aggregate due to ASR............ 3-4 

Figure 3-6. Transgranular cracks passing through paste and a reactive fine aggregate 

particle...................................................................................................... 3-5 
AC 150/5380-8 2/2/04 

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viii

Figure 3-7. Presence of gel with transverse cracks (→) at the interface between 

reactive aggregate (A) and cement paste (B)........................................... 3-5 

Figure 3-8. Accumulation of gel (→) at the periphery of an air void ........................ 3-6 

Figure 3-9. ASR gel with transverse cracks (→) inside a reactive aggregate ........... 3-6 

Figure 3-10. SEM image of rosette like crystalline ASR gel product.......................... 3-8 

Figure 3-11. Crystalline lamellar gel at the surface of aggregate................................. 3-8 

Figure 3-12. SEM image of massive type amorphous ASR gel................................... 3-9 

Figure 8-1. Test equipment showing the principal parts, such as the container, 

 linear variable differential transducer (LVDT), float, and tower ............ 8-3 

Figure 8-2. Reactive aggregate and non-reactive aggregate....................................... 8-5 

Figure 8-3. Expansion curves of aggregate at 14 days ............................................... 8-7 

Figure 8-4. Effect of operating temperature on development of ASR expansion ...... 8-8 

Figure 8-5. Expansion of reactive aggregate in 1N and 0.5N NaOH solution ........... 8-9 

Figure 8-6. Expansion of reactive and non-reactive aggregate in 0.25N NaOH 

solution..................................................................................................... 8-9 

Figure 8-7. Effect of lithium nitrate on ASR expansion of reactive aggregate at 

three different operating temperatures................................................... 8-10 

Figure 8-8. Effect of calcium hydroxide on ASR expansion of reactive aggregate . 8-11 

Figure 8-9. Repeatability of dilatometer test ............................................................ 8-12 
2/2/04 AC 150/5380-8 

 Appendix 1 

1-1 

Chapter 1: Understanding Alkali-Silica Reactivity 

1.1 Definition 

Alkali-silica reactivity (ASR) occurs either in mortar or concrete. A deleterious chemical 

reaction between hydroxyl (OH–) ions associated with alkalis (sodium and potassium) 

present in cement or other sources and certain reactive siliceous components that may be 

present in coarse or fine aggregates, produces a gel. When this alkali-silica gel absorbs 

moisture, it expands, and eventually produces cracks in aggregate particles as well as in 

the cement paste in concrete. 

Three conditions must be satisfied for expansive ASR to occur. 

1. A reactive form of silica or silicate must be present in the aggregate. 

2. Sufficient alkali, sodium (Na) and/or potassium (K), mainly from cement, must be 

available. 

3. Sufficient moisture, i.e., not less than 85% relative humidity (RH) in the pore 

structure of the concrete or mortar, is required. 

If any of the above conditions is lacking, detrimental expansion due to ASR cannot occur. 

1.2 Essential parameters for ASR 

1.2.1 Reactive aggregate 

What is reactive aggregate? 

A simplified example of different forms of silica is provided to explain this. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

1-2 

 

 

 (A) (B)

 

Figure 1-1. Non-reactive quartz. The entire quartz grain is either uniformly bright (A) or 

totally dark (B) under cross-polarized light when the microscope stage is rotated 360°. 

Silica (SiO2) 

Crystalline, e.g., 

Quartz 

 

Crypto-crystalline, 

i.e., extremely fine 

crystalline, e.g., 

Chalcedony

Amorphous or 

glassy, i.e., noncrystalline, e.g., Opal 

Usually non-reactive 

(Figure 1), but 

strained quartz can 

be reactive (Figure 2) 

Reactive 

(Figure 3) 

Highly reactive 
2/2/04 AC 150/5380-8 

 Appendix 1 

1-3 

Figure 1-2. Reactive or strained quartz exhibits dark (A) and light bands (B) within a 

single grain. 

Figure 1-3. Photomicrograph of a very fine grained (cryptocrystalline) chalcedony 

aggregate in concrete. Note the characteristic acicular crystals of chalcedony. (→) 

Thus, it is the form of silica that determines whether a siliceous aggregate is reactive or 

not. Many of the coarse aggregates used in the U.S.A. are siliceous in composition, i.e., 

high in silica (SiO2) content. However, they are not necessarily reactive. 

Certain reactive aggregates do not exhibit maximum expansion unless the aggregate is 

present in a critical range. The proportion of reactive aggregate particles that produces 

maximum expansion for a given alkali content and water-cementitious ratio (W/C) in 

concrete is known as the pessimum proportion. For example, 3% opal in aggregate shows 

maximum expansion. With parameters such as alkali content, W/C, etc. being constant, 

A

B
AC 150/5380-8 2/2/04 

Appendix 1 

 

1-4 

the difference in expansion of different potentially reactive aggregates mainly depends on 

(i) the inherent reactivity of their constituent mineral phases or rock types, (ii) grain size 

of the reactive particle, and (iii) the proportion of these reactive phases within the 

reactive aggregate. Not all aggregates that are susceptible to ASR, however, show the 

pessimum effect. Aggregates without this pessimum effect exhibit increasing expansion 

as a function of the amount of reactive particles present in the aggregate. 

Fine aggregate is more susceptible to ASR because of its higher surface area. 

1.2.2 Higher concentration of alkali 

What is alkali? 

The periodic table shows the position (→) of alkalis (sodium [Na] and potassium [K]), 

i.e. second and third elements in Group I, the alkali metal group. 

Concrete consists of innumerable pores that are often filled with solution containing 

alkalis (Na+

, K+) and hydroxyl (OH–) ions. The alkali level in the pore solution must be 

high for ASR to occur. Following are the sources of alkalis in concrete. 

1. Alkalis from cement ⎯ Cement is the major source of soluble alkalis due to 

hydration of cement minerals. According to the American Society for Testing 

and Materials (ASTM) C 150, 0.6% is the standard option when specifying lowalkali cement. However, it is reported that even this value may be high when 

used with reactive aggregate. 

2. Alkalis from de-icing salts ⎯ these salts are a common source of alkalis in areas 

where de-icing salts are used. However, airport authority takes painstaking 

efforts to subject all chemicals to tests that preclude those that would harm the 
2/2/04 AC 150/5380-8 

 Appendix 1 

1-5 

aircraft and airport support infrastructure. This potential is minimal to rare on the 

airside. 

3. Supplementary cementing materials ⎯ For example, fly ash with a high alkali 

content can introduce alkali. 

4. Aggregates ⎯ Some aggregates themselves may be a potential source of alkalis. 

Typically, alkalis are released when the aggregate’s lattice structure begins to 

break down during ASR. These alkalis later provide an additional source for 

further ASR. 

1.2.3 Environmental factors 

Availability of sufficient moisture ⎯ Moisture is an essential ingredient for ASR; this 

reaction cannot occur in the absence of moisture. Moisture can have a significant impact 

on the severity of distress as well. The ASR gel is hygroscopic, i.e., it absorbs moisture. 

Therefore, higher humidity can increase moisture absorption and thus cause greater 

expansion in concrete. 

Effect of temperature ⎯ The rate of ASR development increases with increasing 

temperature. 

Combination of factors ⎯ ASR-induced deterioration is more severe in portions of a 

concrete structure subjected to repeated wetting and drying or freeze-thaw cycles, in 

addition to the effects of higher temperature and higher moisture. 

1.3 Mechanism of ASR 

Broadly, the ASR mechanism can be divided into two parts: (1) the actual chemical 

reaction, and (2) distress arising from the chemical reaction. 

(1) Reaction mechanism 

The chemical reaction between the alkali hydroxides and reactive silica is essentially a 

dissolution reaction, i.e., solubility of reactive silica in high-alkaline (high pH) solution. 

Basically, the hydroxyl (OH–

) ions attack the stronger siloxane bridge (Si-O-Si) near the 

surface of the reactive siliceous component and break it down. The negative charge 

created by this breakdown is balanced by the positively charged alkali ions, such as Na+

or K+. 

Si-O-Si + 2NaOH (KOH) 2 Si-O–-Na+ (K+) + H2O ------------------(i) 

As the reaction proceeds, alkali hydroxides penetrate into the siliceous particle, thus 

loosening the lattice structure. This type of breakdown of the lattice structure by alkali 

hydroxide is practically impossible in well-crystallized silica (quartz), but is much greater 
AC 150/5380-8 2/2/04 

Appendix 1 

 

1-6 

in crypto-crystalline and amorphous silica because of increased surface area and a 

disordered, open lattice structure. The breakdown of the silica lattice due to alkali attack 

is illustrated in Figure 1-4. 

 

Figure 1-4. Attack of alkali solution on silica lattice. 

In the case of non-reactive quartz, the alkali ions cannot penetrate the well-ordered 

crystal lattice. However, silica minerals with poorly crystallized, disordered crystal 

lattice such as strained quartz, chalcedony are susceptible to alkali attack, as shown in 

Figure 1-4. 

 Si

O 

OH–

Na+

 Ordered/Well Crystallized Disordered/Poorly Crystallized
2/2/04 AC 150/5380-8 

 Appendix 1 

1-7 

(2) Distress mechanism 

The distress mechanism can be explained by the following flow chart. 

Development of a high concentration of alkali hydroxide in the pore solution of 

concrete or mortar and migration of alkalis through the pore solution to reactive 

aggregate sites. 

Reaction between alkali hydroxides and reactive siliceous component within 

aggregate particles, and formation of reaction product, called gel (a viscous 

material composed essentially of silica, alkali [sodium or potassium], calcium, 

and water).

Absorption of water by this gel creates expansive forces on the surrounding cement 

paste, which is in a state of constraint. 

Gel reaction product + Moisture → Expansion

Stress develops by expansive forces that exceed the tensile strength of the cement 

paste, thus causing cracks. 

Movement of the gel from the aggregate into the paste through cracks is enhanced 

by calcium absorption from calcium hydroxide. Later, the gel fills these cracks and 

exerts more expansive pressure, causing further distress. 

2/2/04 AC 150/5380-8 

 Appendix 1 

2-1 

Chapter 2: Field Diagnosis of ASR 

It is preferable that qualified personnel carry out diagnosis in the field. In order to 

undertake field inspection of airfield pavement, it is essential for the inspector to have a 

basic knowledge of the different types of distress that occur in pavements. The most 

readily identifiable distress feature is cracking. Cracking, however, can be of several 

types, such as: 

Linear or longitudinal/transverse cracking 

Map cracking 

Corner break 

D-cracking 

Each of these has been cited later in this chapter. One must recognize that several 

factors can cause cracking in pavement. 

2.1 Background information 

The following data should be recorded before inspection. 

1. Concrete mixture proportions, if available. Otherwise, whether fly ash or slag 

was used in the concrete. 

2. Approximate dates of construction, because segments of airfield pavements may 

have been constructed at different times. 

3. Average relative humidity at the airfield. 

4. Annual precipitation. 

5. Temperature variation. 

6. Use of de-icing chemicals and type, if any. 

7. Water runoff. 

8. Freezing and thawing, if any. 

2.2 Visual manifestation of ASR in airfield pavements 

A detailed field survey is normally the first stage for identifying the possible presence of 

ASR, and the extent of deterioration. The visual signs to be considered in an airfield 

pavement include the following. 

1. Laddering ⎯ Fine, short, parallel cracks that are perpendicular to joints and 

normally appear on both sides of a joint at the initial stage of ASR (Figures 2-1 

and 2-2). 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-2 

Figure 2-1. Laddering (→) along a joint due to ASR 

Figure 2-2. A close-up view of laddering (→). 

2. Map-cracking ⎯ A matrix of fine cracks in non-reinforced concrete slab in 

pavements. Map cracking is never distributed uniformly on the surface of a 

pavement. Its appearance can vary from just a few cracks (Figure 2-3) to isolated 

areas of pattern cracking to fairly severe, closely spaced extensive map cracking 

(Figures 2-3 and 2-4), i.e., the crack density on the surface may vary. It must be 

noted that it is often difficult to distinguish map cracking from crazing, the latter 

arises from improper finishing and curing and do not affect the structural integrity 

of concrete. 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-3 

Figure 2-3. Only a few map cracks (→). 

Figure 2-4. Widespread map cracking. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-4 

Figure 2-5. Severe map cracking. 

3. Aggregate pop-out ⎯ it can occur at the pavement surface due to swelling of the 

gel. Typically, a portion of an affected, exposed aggregate particle breaks away. 

Sometimes, part of the mortar attached to the aggregate is also removed with it, 

leaving a conical-type depression at the surface of the concrete pavement (Figures 

2-6 and 2-7). Aggregate pop-out is not typical of ASR, and can also occur due to 

frost action on shale particles or porous chert particles. 

Figure 2-6. Aggregate pop-out (→). 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-5 

Figure 2-7. Several aggregate particles (A) have been dislodged (→) along with 

some neighboring paste. 

4. Reaction rims around aggregate particles ⎯ A reaction rim can be described as 

a peripheral discoloration of aggregate. This feature is often visible to the naked 

eye or under a hand lens. When examined under a petrological microscope, 

reaction rims are more positively identifiable (see Chapter 3 for details). 

5. Open or gel-filled cracks in aggregate particles ⎯ Usually this is associated with 

an aggregate reaction rim. An illustration is provided in Figure 2-8. 

Figure 2-8. An open internal crack (→) in an ASR-affected aggregate particle (A). 

A

A
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Appendix 1 

 

2-6 

6. Exudation ⎯ Moisture movement through pores and cracks in concrete transport 

the ASR gel to the surface, where it exudes. However, ASR gel exudation is not 

very common, and where present, indicates that there has been sufficient moisture 

to carry the gel to the surface. This exuded gel is usually grayish white (Figures 

2-9 and 2-10). Eventually, the original gel can become a white crystalline 

material due to carbonation. 

Figure 2-9. Gel exudation through cracks. 

Figure 2-10. Gel exudation (→) through cracks. 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-7 

2.3 Structural evidence of expansion due to ASR 

1. Closure of joints ⎯ Some of the expansion joints in a pavement may close or 

become compressed due to horizontal slab movement. (Figure 2-11). This 

compression may give rise to joint sealant damage, e.g., squeezing out joint 

sealant because of high compression. Figure 2-12 clearly shows the heaving of an 

asphalt shoulder due to expansive movement of the adjoining concrete pavement 

slab in an airfield severely affected by ASR. 

Figure 2-11. Joint compression due (→) to slab movement. 

Figure 2-12. Heaving (→) of an asphalt shoulder due to movement of adjoining 

concrete slab affected by ASR. Movement has been so severe that it has distorted the 

concrete columns ( ) of a neighboring building. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-8 

(b) Joint misalignment ⎯ Further compression on the joint causes misalignment of 

 joints (Figures 2-13) 

Figure 2-13. Misalignment of joint (→) caused by slab movement. 

2. Blowup/buckling/heaving ⎯ Expansion due to ASR can cause a concrete slab to 

move upward to relieve compression restraint (Figure 2-14). When one slab 

heaves up relative to an adjoining slab in a runway, it can become a source of 

potential hazard for aircraft landing. Slabs are reported to have been ground 

down a few times during their service life to provide a smooth and level runway 

surface. 

Figure 2-14. Heaving of a slab relative to another 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-9 

Restraint can influence the development of cracks due to ASR. Cracking may not occur 

uniformly throughout a structure if expansive forces are less than restraining forces. 

Most commonly, cracking will be partially or completely suppressed in the direction of 

the restraint (e.g. steel reinforcement in one direction). 

2.4 Distinction between ASR distress features and other types of distress 

 features in airfield pavements 

Deterioration arising from ASR and other mechanisms often looks very similar. This 

similarity makes positive identification of ASR virtually impossible from visual 

inspection alone. Nevertheless, the visual indicators of ASR listed in sections 2.2 and 2.3 

should be considered as preliminary evidence. However, laboratory investigation is 

essential to confirm ASR. The roles of structural design of the pavement, concrete 

mixture proportions, age of the pavement, and climatic factors in the deterioration 

process should be evaluated before considering the influence of other major distress 

mechanisms, such as freeze-thaw, sulfate attack, carbonation, leaching, etc. 

One deterioration mechanism often complements another to accelerate concrete 

deterioration, e.g., (a) initial cracks formed by freeze-thaw or shrinkage can generate 

better access for moisture to migrate deeper, and thus increase the risk of further damage; 

(b) portland cement may provide the alkali necessary for ASR to initiate, but the reaction 

may be aggravated by other sources of alkalis described earlier in Section 1.2.2 (Chapter 

1), and (c) in airfield pavements, it is necessary to consider the stresses induced during 

aircraft landing and maneuvering. 

2.4.1 Distress criteria 

The following features can be helpful to distinguish other distress mechanisms. 

1. Sub parallel cracking and cracking restricted to the near surface with scaling and 

spalling of the exposed surface and edges are primarily associated with freezethaw damage. A surface attacked by frost is rough and irregular. 

2. Alkali-silica reactivity by itself does not usually cause disintegration of the 

surface, except for aggregate pop-outs. 

3. D-cracking is primarily caused by freeze-thaw. This distress usually appears as a 

pattern of cracks running parallel and close to a joint. Depending on the severity 

of distress, loosening or displacement of concrete in the cracked region can occur. 

This D-cracking may eventually lead to disintegration of the concrete within 1 to 

2 ft of the joint or crack (Figure 2-15). 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-10 

Figure 2-15. D-cracking (→) in an airfield pavement. 

If any of these distress criteria are present in an airfield pavement located in a 

region vulnerable to freeze-thaw, then one must exercise caution in identifying the 

primary cause of distress. 

4. Severe exfoliation, that is, when layers of concrete are detached from the surface, 

generally caused by sulfate attack. However, chemical analysis, x-ray diffraction 

(XRD) or scanning electron microscope-energy dispersive spectroscopy (SEMEDS) is essential for proper identification of reaction products, e.g., abundance of 

gypsum, ettringite, etc., to confirm sulfate attack. 

5. Porous aggregates that undergo freeze-thaw attack can also cause pop-outs. In the 

case of ASR, the gel, if present, can be identified from visual inspection of the 

region of the crater created by pop-out. Typically, one or two additional 

symptoms of ASR, such as map cracking, laddering, misalignment of joints, etc. 

are associated with the pop-out. 

6. Corner breaks (Figure 2-16), corner spall (Figure 2-17), joint spall (Figure 2-18), 

and transverse/longitudinal cracks (Figure 2-19) are caused by other distress 

mechanisms. 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-11 

Figure 2-16. Corner break (→) in an airfield pavement. 

Figure 2-17. Corner spall in another airfield pavement. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-12 

Figure 2-18. Longitudinal joint spall (→). 

Figure 2-19. Longitudinal cracks (→) in an airfield pavement. 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-13 

2.5 Application of dyes to detect ASR gel in the field 

Use of the uranyl (uranium) acetate fluorescence method (UAFM) ⎯ Often it is not very 

easy to identify ASR gel in the field with the unaided eye. The surface of the pavement 

may be covered with dirt and grime deposited over many years. The dye method can be 

used on any concrete surface to identify ASR gel. The gel may be present in varying 

proportions in aggregate rims and cracks, air voids, fractures, and on the exposed surface 

of concrete as exudation. By applying uranyl acetate solution to the surface, the gel, if 

present in an unaltered state, imparts a characteristic yellowish green glow in ultraviolet 

(UV) light (254 nm) because of uranyl ion substitution for alkali in the gel. The gel 

fluoresces much more brightly than cement paste due to the higher concentration of 

alkali. The following steps are recommended for use of this method. All safety 

precautions must be followed while preparing and using this solution. Gloves must 

be worn when using some of these dyes. The Material Safety Data Sheet (MSDS) 

must be consulted before using dyes. 

Step 1: Uranyl acetate solution ⎯ Prepare a dilute acetic acid solution by adding 5 mL of 

glacial acetic acid to distilled water to make up 200 mL of solution. Add 5 g uranyl 

acetate powder to the dilute acetic acid solution. Warm but do not boil to dissolve the 

powder. The process will not work properly if the solution boils. 

Step 2: A fresh concrete surface free of laitance and carbonation is required. This can be 

exposed at approximately 1⁄4 inch depth using a rotary hammer, hammering by hand, or 

by sawing. 

Step 3: Powder concrete must be rinsed off the surface with water. 

Step 4: The uranyl acetate solution is sprayed on the fresh concrete surface, allowed to 

react for 5 minutes, and the surface is rinsed with water. 

Step 5: A light-excluding viewing box (portable darkroom) containing ultra violet (UV) 

light is used because the fluorescence of the silica gel due to absorption of uranium ions 

is too faint to see in daylight. 

Source: 

Uranyl acetate is available from any chemical supplier. 

Ultra violet light box – A viewing box that can be placed over the surface to be viewed. 

Provision must be made for a UV light lamp and for excluding ordinary light. 

Use of other dyes such as cuprammonium sulfate solution does not provide very effective 

coloration to enable clear distinction of ASR. 

 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-14 

2.6 Selection of coring locations for further laboratory investigation 

If some definite indications of ASR are obtained from visual inspection of the pavement, 

then the next step is to collect cores from strategic locations for further laboratory 

investigation. Airfield pavements generally consist of a series of slabs. Very often these 

slabs were constructed at different times. So it is likely that different concrete mixture 

proportions were used. Background information about the different slabs in a concrete 

pavement, if available, can be useful for selecting coring locations. The location and 

number of cores should depend on the following: 

1. Severity of distress ⎯ The severity of external cracking may not necessarily 

correlate with the severity of internal damage. So, collecting a full-depth core is 

always desirable. In general, it is recommended to collect one core per each 

distress feature. If the severity of a distress feature varies, e.g., from low to high 

then the engineer has the option to collect more than one core, for example, one 

from high-severity area and another from low severity area. Similarly, if the 

distribution pattern of a particular distress feature (such as map-cracking) is 

repetitive from one sample unit to another, then the engineer has the option to 

reduce the coring rating. 

 In fact, cores from adjacent pavements without visual distress may be appropriate 

 when attempting to determine the severity of distress. In some instances, ASR 

 distress can be very localized and limited to small pockets where reactive 

 aggregates were used (see Figure 2-3). 

2. Age of concrete ⎯ If possible, cores from sections of different construction ages 

should be selected. 

3. Concrete mixture proportions/Presence or absence of fly ash or slag ⎯ Cores 

from slabs/sections with different mixture proportions or at least whether fly 

ash/slag was used in the concrete should be included in the coring plan. 

4. Variation in concentration of cracking within a slab ⎯ the concentration of 

cracking may vary from one section to another within the same slab as shown in 

Figures 2-20 and 2-21. If necessary, cores should be collected from different 

affected parts of the same slab to determine if ASR is localized or global distress. 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-15 

Figure 2-20. Cracks (→) in the central part of a pavement section.

Figure 2-21. Different cracking pattern (→) near the joint of the same pavement section. 

Airfield pavement slabs may be as thick as 18 inches. Full-depth cores are recommended 

because there may be variation in cracking and distress pattern in the upper, intermediate, 

and bottom portions of the slab. This will also enable assessment of ASR-related distress 

as a function of depth. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

2-16 

The diameter of the cores should be at least 2 inches; otherwise, in situ recovery of core 

may be difficult. 

2.6.1 Visual inspection of cores 

Visual examination of the drilled cores with the unaided eye or a hand lens can often 

provide useful information about the type and extent of distress. The features to look for 

include the following: 

1. Hairline cracks, originally due to drying shrinkage or some other distress 

mechanism, 

2. Peripheral discoloration of aggregate, and 

3. White gel around aggregate particles. 

 An illustration is provided in Figure 2-22. 

Figure 2-22. Full-depth cores from sections of an airfield pavement showing different 

distress features, such as short vertical cracks (A), horizontal cracks (B), peripheral 

discoloration of aggregate (C), and cracked aggregate (D). 

A 

B 

B 

C B

D 
2/2/04 AC 150/5380-8 

 Appendix 1 

2-17 

2.7 Summary 

A summary is presented in order to reinforce the steps involved in a performing a 

thorough field investigation. 

 

• Visual signs to be considered: map-cracking, laddering, aggregate pop-out, 

reaction rim around aggregate particle, open or gel-filled cracks in aggregate 

particle, gel exudation. 

• Structural evidence of expansion due to ASR to be considered – joint closure, 

joint seal damage, joint misalignment, blowup/heaving. 

• UAFM dye test method in field to detect ASR gel in visible cracks (applicable 

only if gel is present in an unaltered state). Unaltered gel if present, can be 

identified in cracks, and fractures on the exposed surface of pavement by its 

characteristic yellowish-green glow under UV light. 

Coring for further laboratory investigation: 

• In general, it is recommended to collect one core per distress feature. 

• If the severity of a distress feature varies, e.g., from low to high then the engineer 

has the option to collect more than one core, for example, one from high-severity 

area and another from low severity area. Similarly, if the distribution pattern of a 

particular distress feature (such as map-cracking) is repetitive from one sample 

unit to another, then the engineer has the option to reduce the coring rating. 

• Collect full-depth cores with diameter of at least 2 inch., but not larger than 4 

inch. 

2/2/04 AC 150/5380-8 

 Appendix 1 

3-1 

Chapter 3: Laboratory Investigations 

3.1 Use of dye 

Slicing the full-depth drilled core at three or more different depths is desirable. All the 

sections must be properly identified and marked for orientation. Examination of these 

sections by the same dye method described in Chapter 2 can help to detect whether the 

gel is present throughout the core and, if so, the relative amount at different depths. 

The dye test indicates the presence of unaltered ASR gel, but it is not a decision-making 

tool. Neither can the amount of gel be quantified by this method. Therefore, one must 

not rely solely on this test. Additional laboratory tests are strongly recommended. The 

advantage of using UAFM is demonstrated below in Figures 3-1 and 3-2. 

 

Figure 3-1. A slice of a concrete core collected from an airfield pavement under plain 

light (scale: 1= 1.75). 
AC 150/5380-8 2/2/04 

Appendix 1 

 

3-2 

Figure 3-2. The same section after dye treatment when viewed under UV light shows 

ASR gel along cracks and around aggregate periphery (→). Scale: 1=1.75

3.2 Optical microscopic techniques to identify ASR 

3.2.1 Optical microscopy 

A polarizing light microscope, typically in the magnification range of ~32× – 800× is 

used for petrographic analysis. The resolution of a petrographic microscope is between 5 

and 10 μm. The polarizing light or petrographic microscope is designed to analyze light 

transmitted through or reflected from a sample. Optical microscopy utilizes crosspolarization of light. Qualitative data can be derived from microscopic examination. 

Thin concrete sections are studied in the transmitted-light mode; the reflected-light mode 

is more suited for examination of polished samples. Most modern petrographic 

microscopes are equipped with both light sources. A camera attached to the microscope 

has become a standard accessory for photographically recording important observations. 

Optical microscopy is a highly useful, simple, and inexpensive tool for identifying ASR. 

While optical microscopy offers a relatively rapid means of diagnosing ASR, sample 

preparation is elaborate, time-consuming, and somewhat demanding. Nevertheless, 

optical microscopy can reliably serve to identify the deterioration features of ASR. 

Although it can provide some definite answers, additional testing, if available, is strongly 

recommended. 

A resin-soluble blue dye can be vacuum impregnated during sample preparation. The use 

of dye facilitates recognition of micro cracks and voids. 
2/2/04 AC 150/5380-8 

 Appendix 1 

3-3 

Commensurate with the cut sections of the core, petrographic examination of at least 

three thin or polished sections are recommended from a full-length core. The top 2 

inches should be avoided because accumulation of dirt along cracks generally masks 

distress features. 

3.2.2 Identification of ASR features under the microscope 

Petrographic examination involves identifying the characteristic features of ASR, such 

as peripheral discoloration, reaction rims, polygonal cracking of aggregate, micro cracks 

in paste, presence of gel, etc. Microphotographs (Figures 3-3 through 3-4) are provided 

to illustrate these features. The blue areas in these photomicrographs represent vacant 

spaces, for examples, empty cracks and air voids. 

Figure 3-3. Reaction rim (→) around an aggregate (A) particle due to ASR. 

Magnification 100X. 

A
AC 150/5380-8 2/2/04 

Appendix 1 

 

3-4 

Figure 3-4. Peripheral discoloration (→) of an opaline limestone aggregate (A) particle. 

Magnification 200X 

Figure 3-5. A severely cracked opaline siliceous fine aggregate due to ASR. 

Magnification 40X 

A
2/2/04 AC 150/5380-8 

 Appendix 1 

3-5 

Figure 3-6. Transgranular cracks passing through paste and a reactive fine aggregate 

particle. Note the presence of gel (→) at the edges of cracks inside the aggregate. 

Magnification 40X. 

Figure 3-7. Presence of gel (C) with transverse cracks (→) at the interface between 

reactive aggregate (A) and cement paste (B). Magnification 100X. 

A 

B

C
AC 150/5380-8 2/2/04 

Appendix 1 

 

3-6 

Figure 3-8. Accumulation of gel (→) at the periphery of an air void. Magnification 

40X. 

Rapid identification of gel ⎯ The ASR gel is a clear transparent material with transverse 

cracks in plane-polarized light and is isotropic under cross-polarized light, i.e., it remains 

dark through a complete rotation of the microscope stage (Figure 3-9). 

Figure 3-9. ASR gel with transverse cracks (→) inside a reactive aggregate. 

Magnification 40X. 
2/2/04 AC 150/5380-8 

 Appendix 1 

3-7 

Identification of reactive aggregates ⎯ Both coarse and fine aggregates may be reactive. 

Therefore, both should be carefully examined petrographically. Figures 1-2 and 1-3 

presented in Chapter 1 show a few examples of different forms of reactive silica. 

3.3 Scanning electron microscopy/energy dispersive X-ray analysis 

A scanning electron microscope (SEM) uses a primary electron beam to scan the 

specimen surface. SEM allows direct observation of surface topography. Very low 

(20×) to very high (50, 000×) magnification can be selected. SEM provides a much 

greater depth of field than optical microscopes, creating a three dimensional effect. In 

addition, SEM imagery is easy to interpret, especially in combination with energy 

dispersive X-ray analyzer (EDXA). 

One of SEM’s greatest advantages lies in the possibility of examining fractured concrete 

specimens, although flat polished specimens can also be observed with relative ease. 

Samples can be in any form, provided they can withstand the high vacuum required in the 

specimen chamber for the operation of the microscope. Concrete samples must be treated 

with a thin conductive coating of gold (Au), gold-palladium (Au-Pd), or carbon (C) prior 

to observation under the microscope to prevent charge build up on the surface. 

 

EDXA is used in conjunction with SEM. EDXA determines the elemental analysis of the 

phases by analyzing the characteristic X-rays generated by an electron beam. Therefore, 

confirmation of the presence of ASR gel and its composition can be ascertained by SEMEDXA. Crystalline and amorphous gel can be clearly distinguished by SEM. Since 

EDXA analysis cannot be restricted to an arbitrary small volume, spurious contributions 

as a result of the beam passing through the crystal being analyzed may jeopardize 

accurate analysis. 

Scanning electron microscopy involves identifying ASR gel by its characteristic 

morphology. Typical morphologies of gel, namely rosette types (Figure 3-10), lamellar 

types (Figure 3-11) which are the crystalline variety, and massive cracked types (Figure 

3-12) which is non-crystalline, can be used as diagnostic features to confirm ASR. 

 
AC 150/5380-8 2/2/04 

Appendix 1 

 

3-8 

Figure 3-10. SEM image of rosette like crystalline ASR gel product. 

Figure 3-11. Crystalline lamellar gel at the surface of aggregate. 
2/2/04 AC 150/5380-8 

 Appendix 1 

3-9 

Figure 3-12. SEM image of massive type amorphous ASR gel. 

2/2/04 AC 150/5380-8 

 Appendix 1 

4-1 

Chapter 4: ASR Distress Analysis in Airfield Pavements 

4.1 ASR condition survey 

The condition survey of ASR in airfield pavements is based on identification of critical 

distress features from visual inspection, followed by laboratory investigation, if any 

symptoms of ASR are detected. The modified survey data sheet, which is based on the 

original condition survey of distress data sheet in ASTM 5340 Airport Pavement 

Condition Index Surveys, is presented in Table 1. Modifiers, that is, characteristic 

features related to ASR distress, have been in added to the original list of distress types in 

the survey sheet in order to provide a more authentic ASR distress rating. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

4-2 

 Table 1: ASR condition survey data sheet for jointed airfield pavement

 Jointed Rigid Pavement 

ASR Condition Survey Data Sheet for Sample Unit

Facility Sample unit Date 

Year of Construction Average RH 

Average Annual Rainfall Slab Dimensions 

Other Aggravating Factors

 Score (A) 

Fly ash/ Slag Y N 

De-icing Y N 

Salt 

Freeze-thaw+ Y N 

Average RH 

Average Rainfall 

 

 Sum 

 

+ If “Y” then, on an average 

 cycles per year

 Direction of Survey 

 

 

5 

 

 

 4 

 

 

3 

2 

 

1 

 

 1 2 3 4

Distress types Modifiers 

1 – Blow up, 2 – Corner break (a) Laddering 

5– Joint seal damage 8 – pop-outs (b) Aggregate cracking 

10 – Scaling / Map-cracks/crazing (c) Gel exudation 

11 – Settlement / Fault (d) Joint closure 

13 – Shrinkage crack (e) Joint misalignment 

14 - Spalling (joints) 15 – Spalling (corner) (f) Heaving 

 

Visual inspection Laboratory Investigation 

Score of ASR Features from 

Laboratory Investigation

Petrography/SEMEDXA 

Critical 

ASR 

Features

Score of 

the ASR 

Features 

(B) 

UAFM 

Test in 

Field 

No. 

Core 

** 

UAFM 

(C1) Gel 

(C2) 

Agg. 

Crack. 

(C3) 

 RR 

(C4) 

 

10* (c) Y 13*

 (a) Y 10H Y (c) Y (b) Y 5*

 (d) 

(e) N 

1* 5* (d) 

(e) N 

11* (f) N 2 H N 15 H N 14 H N Sum Avg. 

Total Score: Distress Rating: 

Residual Service Life: 

Total score = Sum (A) + Sum (B) + Avg. (C1) + Avg. (C2) + Avg. 

 (C3) + Avg. (C4) 

* All levels of severity ** One core/distress feature RR – Reaction Rim 

RH – Relative Humidity 
2/2/04 AC 150/5380-8 

 Appendix 1 

4-3 

4.2 Scoring of ASR distress 

Visual inspection 

• Based on degree of severity of critical ASR features 

• High – 8, Medium to high – 6, Medium – 4, Low to medium – 3, low - 2

Laboratory Investigation 

From petrography 

• Reaction rim 

 12 – prominent and thick, 8 – intermediate, 4 – faint, 0 – absent 

• Presence of gel 

 12 – repetitive and frequently occurring in cracks, air-voids, aggregate - paste 

 interface, inside cracked aggregate, 8 – localized, 4 - trace, 0 – absent 

• Aggregate cracking 

 12 – intense, 8 – intermediate, 4 – trace, 0 – absent 

From UAFM test 

• 12 – strongly affirmative (repetitive at different depths and frequently occurring 

either in cracks, air voids, or at aggregate – paste interface), 8 – affirmative 

(presence of gel is confirmed but not repetitive and frequently occurring and 4 – 

negative (gel not detected). It does not necessarily signify that gel is absent. 

Effect of other aggravating factors on ASR 

• Average annual rainfall (inches) 

 5 – high (>40//), 3 – moderate (20-30//), 1 – low (< 15//) 

• Average relative humidity (%) 

 3 – high (> 80%), 2 – moderate (70–40%), 1 – low (<30%) 

 
AC 150/5380-8 2/2/04 

Appendix 1 

 

4-4 

• Freeze-thaw cycles 

 3 – high (20 cycles per year), 2 – moderate (10 cycles per year), 1 – low (5 cycles 

 per year), 0 – absent 

• Use of de-icing salt 

 3 – used and alkali-bearing, 1 – used, but non alkali-bearing, 0 – never used 

• Use of Fly ash 

 4 – not used, 3 – low fly ash proportion (< 20%), 2 – moderate fly ash proportion 

 (20-30%), 1 – high fly ash proportion (> 30%). 

• Use of ground granulated blast furnace slag 

 4 – not used, 3 – low slag proportion (25-40%), 2 – moderate slag proportion (40- 

 50%), 1 – high slag proportion (> 50%). 

Total Score = score of other aggravating factors (sum of “A”) + score of visual 

inspection (sum of “B”) + score of laboratory investigation (Avg. C1 + Avg. C2 + 

Avg. C3 + Avg. C4) 

Distress rating from total score 

High – when total score is > 75 

Moderate – when total score is 75-45 

Low – when total score is < 45 
2/2/04 AC 150/5380-8 

 Appendix 1 

4-5 

Example 1: ASR condition survey for an airfield pavement section (containing different 

sample units) with high-severity ASR 

Jointed Rigid Pavement 

ASR Condition Survey Data Sheet for Sample Unit

Facility RWY Sample Unit 1 Date 3/15/02

Year of Construction: 1957 Average RH: >30% 

Average Annual Rainfall: > 15 inch Slab Dimensions 25 x 25 FT

Other Aggravating Factors

 Score (A) 

Fly ash/ Slag Y N 4 

De-icing Y N 0 

Salt 

Freeze-thaw Y N 0 

Average RH 1 

Average Rainfall 1 

 

 Sum 6 

 

 Direction of Survey 

 

 

5 10(c)MH 5M 10 H 

 10 H 13(a)M 

 

 10(c) MH 10H 5(d)(e) MH 

 4 13(a)M 13(a) M 

 5(d)(e)M 

 

3 11(f)M (b) 5(d)(e) M 

2 10H 10 (c)MH 

 (b) (c) 10H 1 

 

 1 2 3 4

Distress types Modifiers 

1 – Blow up 2 – Corner break (a) Laddering 

5– Joint seal damage 8 – pop-outs (b) Aggregate cracking 

10 – Scaling / Map-cracks/crazing (c) Gel exudation 

11 – Settlement / Fault (d) Joint closure 

13 – Shrinkage crack (e) Joint misalignment 

14 - Spalling (joints) 15 – Spalling (corner) (f) Heaving 

 

Visual inspection Laboratory Investigation 

Score of ASR Features from 

Laboratory Investigation

Petrography / SEMEDXA 

Critical 

ASR 

Features

Score of 

the ASR 

Features 

(B) 

UAFM 

Test in 

Field 

No. 

Core 

 

UAFM 

(C1) Gel 

(C2) 

Agg. 

Crack. 

(C3) 

 RR 

(C4) 

 

10* (c) 6 Y 2*** 8 12 12 8 

13* (a) 4 Y 1 8 8 8 4 

10H 8 Y 1 4 8 8 4 

(c) 4 Y 0 (b) 2 Y 0 5*

 (d) 

(e) 

4 N 1 

1* 5* (d) 

(e) 

2 N 0 

11* (f) 4 N 1 2 H 2 N 0 15 H 2 N 0 14 H 2 N 0 Sum 40 Avg 7 9 9 5 

Total Score: 76 Distress Rating: High 

Residual Service Life: Less than 5 years 

Total Score = Sum (A) + Sum (B) + Avg. (C1) + Avg. (C2) + Avg. (C3) 

 + Avg. (C4) 

 *** 1 core in high severity area & 1 core in low severity area, 

MH - Moderate to high 
AC 150/5380-8 2/2/04 

Appendix 1 

 

4-6 

Example 2: ASR condition survey for an airfield pavement section (containing different 

sample units) with low-severity ASR 

Jointed Rigid Pavement 

ASR Condition Survey Data Sheet for Sample Unit

Facility RWY Sample unit 2 Date 3/15/02

Year of Construction: 1957 Average RH: >30% 

Average Annual Rainfall: > 15 inch Slab Dimensions 25 x 25 FT

Other Aggravating Factors

 Score (A) 

Fly ash/ Slag Y N 2 

De-icing Y N 0 

Salt 

Freeze-thaw Y N 0 

Average RH 1 

Average Rainfall 1 

 

 Sum 4 

 

 Direction of Survey 

 

 

5 10(c)L 10L 10L 

 13(a)M 

 

 10(c)L 10L 5(d)(e)L 

 4 13(a)M 

 

 

3 13(a)L 5(d)(e)L 

2 10L 

 

1 

 

 1 2 3 4

Distress types Modifiers 

1 – Blow up 2 – Corner break (a) Laddering 

5– Joint seal damage 8 – pop-outs (b) Aggregate cracking 

10 – Scaling / Map-cracks/crazing (c) Gel exudation 

11 – Settlement / Fault (d) Joint closure 

13 – Shrinkage crack (e) Joint misalignment 

14 - Spalling (joints) 15 – Spalling (corner) (f) Heaving 

 

Visual inspection Laboratory Investigation 

Score of ASR Features from 

Laboratory Investigation

Petrography / SEMEDXA 

Critical 

ASR 

Features

Score of 

the ASR 

Features 

(B) 

UAFM 

Test in 

Field 

No. 

Core 

 

UAFM 

(C1) Gel 

(C2) 

Agg. 

Crack. 

(C3) 

 RR 

(C4) 

 

10* (c) 2 Y 1 8 8 4 4 

13* (a) 4 Y 1 4 4 4 0 

10H 2 Y 0 (c) 2 Y 0 (b) 0 Y 0 5*

 (d) 

(e) 

2 N 1 4 4 4 0 

1* 5* (d) 

(e) 

0 N 0 

11* (f) 0 N 0 2 H 0 N 0 15 H 0 N 0 14 H 2 N 0 Sum 14 Avg 5 5 4 1 

Total Score: 33 Distress Rating: Low

Residual Service Life: 15-20 years 

Total Score = Sum(A) + Sum (B) + Avg. (C1) + Avg. (C2) + Avg. (C3) 

 + Avg. (C4) 

 
2/2/04 AC 150/5380-8 

 Appendix 1 

4-7 

Example 3: ASR condition survey for an airfield pavement section (containing different 

sample units) with high-severity ASR. Note that visual manifestation of ASR is 

comparatively low. 

Jointed Rigid Pavement 

ASR Condition Survey Data Sheet for Sample Unit

Facility RWY Sample Unit 3 Date 4/15/02 

Year of Construction: 1940 Average RH: ~80% 

Average Annual Rainfall: ~30 inch Slab Dimensions 12 x 15 FT

Other aggravating factors

 Score (A) 

Fly ash/ Slag Y N 4 

De-icing Y N 1 

Salt 

Freeze-thaw+ Y N 3 

Average RH 3 

Average Rainfall 3 

 

 Sum 14 

 

+ 20 cycles per year

 Direction of Survey 

 

 

5 2H 10L 15H 

 15H 14H 

 

 10(c) L 10(c)L 

 4 13(a)M 

 5(d)(e)M 

 

3 (c) 5(d)(e) M 

2 10L 10 (c)M 

 11L 13(a)L 1 10L 

 

 1 2 3 4

Distress types Modifiers 

1 – Blow up 2 – Corner break (a) Laddering 

5– Joint seal damage 8 – pop-outs (b) Aggregate cracking 

10 – Scaling / Map-cracks/crazing (c) Gel exudation 

11 – Settlement / Fault (d) Joint closure 

13 – Shrinkage crack (e) Joint misalignment 

14 - Spalling (joints) 15 – Spalling (corner) (f) Heaving 

 

Visual inspection Laboratory Investigation 

Score of ASR Features from 

Laboratory Investigation

Petrography / SEMEDXA 

Critical 

ASR 

Features

Score of 

the ASR 

Features 

(B) 

UAFM 

Test in 

Field 

No. 

Core 

 

UAFM 

(C1) Gel 

(C2) 

Agg. 

Crack. 

(C3) 

 RR 

(C4) 

 

10* (c) 2 Y 1 8 8 8 4 

13* (a) 2 Y 1 8 12 12 8 

10H 2 Y 0 (c) 4 Y 1 4 8 12 4 

(b) 4 Y 0 5*

 (d) 

(e) 

4 N 1 

1* 5* (d) 

(e) 

2 N 0 

11* (f) 2 N 1 2 H 6 N 0 15 H 4 N 0 14 H 4 N 0 Sum 36 Avg 7 9 10 5 

Total Score: 81 Distress Rating: High 

Residual Service Life: ~10 years 

Total Score = Sum (A) + Sum (B) + Avg. (C1) + Avg. (C2) + Avg. (C3) 

 + Avg. (C4) 

 
AC 150/5380-8 2/2/04 

Appendix 1 

 

4-8 

Example 4: ASR condition survey for an airfield pavement section (containing different 

sample units) with medium-severity ASR. Note that visual manifestation of ASR is very 

low but laboratory investigation reveals ASR with relatively high intensity inside. 

Jointed Rigid Pavement 

ASR Condition Survey Data Sheet for Sample Unit

Facility RWY Sample Unit 4 Date 4/15/02 

Year of Construction: 1940 Average RH: ~80% 

Average Annual Rainfall: ~30 inch Slab Dimensions 12 x 15 FT

Other Aggravating Factors

 Score (A) 

Fly ash/ Slag Y N 4 

De-icing Y N 1 

Salt 

Freeze-thaw+ Y N 3 

Average RH 3 

Average Rainfall 3 

 

 Sum 14 

 

+ 20 cycles per year

 Direction of Survey 

 

 

5 10(c)L 

 

 

 13(a)L 5(d)(e)L 

 4 

 

 

3 13(a)L 

2 10L 10L 

 

1 

 

 1 2 3 4

Distress types Modifiers 

1 – Blow up 2 – Corner break (a) Laddering 

5– Joint seal damage 8 – pop-outs (b) Aggregate cracking 

10 – Scaling / Map-cracks/crazing (c) Gel exudation 

11 – Settlement / Fault (d) Joint closure 

13 – Shrinkage crack (e) Joint misalignment 

14 - Spalling (joints) 15 – Spalling (corner) (f) Heaving 

 

Visual inspection Laboratory Investigation 

Score of ASR Features from 

Laboratory Investigation

Petrography / SEMEDXA 

Critical 

ASR 

Features

Score of 

the ASR 

Features 

(B) 

UAFM 

Test in 

Field 

No. 

Core 

 

UAFM 

(C1) Gel 

(C2) 

Agg. 

Crack. 

(C3) 

 RR 

(C4) 

 

10* (c) 2 Y 1 8 12 4 4 

13* (a) 2 Y 1 8 8 4 8 

10H 2 Y 0 (c) 0 Y 0 (b) 0 Y 0 5*

 (d) 

(e) 

2 N 1 4 8 8 4 

1* 5* (d) 

(e) 

0 N 0 

11* (f) 0 N 0 2 H 0 N 0 15 H 0 N 0 14 H 2 N 0 Sum 10 Avg 7 9 5 5 

Total Score: 50 Distress Rating: Medium 

Residual Service Life: 10-15 years 

Total Score = Sum (A) + Sum (B) + Avg. (C1) + Avg. (C2) + Avg. 

 (C3) + Avg. (C4) 

 
2/2/04 AC 150/5380-8 

 Appendix 1 

4-9 

4.3 Detailed explanation of the survey sheet 

4.3.1 Other aggravating factors: Data collection and scoring 

Although high moisture, sufficient alkali, reactive aggregate are the essential parameters 

for ASR to occur, other factors related to climate and materials can aggravate ASR. For 

example, supplementary cementitious materials such as fly ash, slag or combination 

thereof in concrete when used in appropriate proportions, have been demonstrated to 

control expansion due to ASR. On the other hand, the use of de-icing salt, or repeated 

occurrence of freeze-thaw cycles can aggravate ASR. Alkali-bearing de-icing salt that 

was used in the past, can act as a source of additional alkali. The frequency of cracks can 

increase as a result of regular freeze-thaw cycles. This in turn can act as passage for 

moisture to penetrate the concrete. Similarly, high relative humidity (RH) condition and 

heavy rainfall can also aggravate ASR. 

4.3.2 Visual inspection 

Identification of critical ASR features and scoring based on degree of severity 

 

• Visual signs to be considered: map-cracking, laddering, aggregate pop-out, 

reaction rim around aggregate particle, open or gel-filled cracks in aggregate 

particle, gel exudation 

• Structural evidence of expansion due to ASR to be considered: joint closure, joint 

seal damage, joint misalignment, blowup/heaving 

UAFM dye test method in field to detect ASR gel in visible cracks (applicable only if gel 

is present in an unaltered state) 

• Unaltered gel if present, can be identified in cracks, and fractures on the exposed 

surface of pavement by its characteristic yellowish-green glow under UV light. 

Coring for further laboratory investigation 

• In general, it is recommended to collect one core per distress feature. 

• If the severity of a distress feature varies, e.g., from low to high then the engineer 

has the option to collect more than one core, for example, one from high-severity 

area and another from low severity area. Similarly, if the distribution pattern of a 

particular distress feature (such as map-cracking) is repetitive from one sample 

unit to another, then the engineer has the option to reduce the coring rating. 

• Collect full-depth cores with diameter of at least 2 inch., but not larger than 4 

inch. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

4-10 

4.3.3 Laboratory Investigation of critical ASR features 

Visual inspection of cores 

• Inspect type of cracks, whether they are due to shrinkage or due to other causes, 

peripheral discoloration of aggregate, white gel around aggregate particle, internal 

cracks in aggregate particles. 

Repeat UAFM dye test method on core samples and scoring based on test result 

• Slice the full-depth drilled core at three or more different depths, example, top, 

middle, and bottom. 

• Examine these sections by the UAFM dye method to detect presence of unaltered 

ASR gel at different depths. 

Gel can be identified (if present) in aggregate rims, cracks, and fractures by its 

characteristic yellowish-green glow under UV light. If the glow is observed then ASR is 

affirmative. 

Application of optical microscopic techniques for confirmation of ASR as indicated 

from visual inspection and scoring 

Identification of critical ASR features 

• Presence of gel inside aggregate, at the cement paste – aggregate interface, in air 

voids and along cracks 

• Cracking of aggregate and micro-cracks in paste 

• Reaction rim around aggregate 

Scanning electron microscopy / energy dispersive X-ray analysis 

• Involves identifying ASR gel by its characteristic morphology, namely rosette 

structure, massive or lamellar type etc. at higher magnification SEM 

• Confirmation of the elemental composition of ASR gel from EDXA 

Complete survey sheet, and assign ASR distress rating in survey sheet. The distress 

rating, e.g., low, medium and high will be based on the combined results of visual 

inspection, laboratory investigation and other aggravating factors related to materials and 

climate. 
2/2/04 AC 150/5380-8 

 Appendix 1 

5-1 

Chapter 5: Mitigation and Prevention of ASR 

5.1 Common preventive measures for ASR 

1. Use non-reactive aggregate, if possible. According to ASTM C1260 test 

(Chapter 7) expansion less than 0.10% at 14 days is indicative of innocuous 

behavior of most aggregates and can be considered as diagnostic feature of nonreactive aggregate. Furthermore, petrographic examination according to 

ASTM C 295 method is desirable to confirm this (Chapter 1, Section 1.2.1). 

2. Use low-alkali cement – typically but not always, less than 0.6% sodium oxide 

(Na2O) cement controls ASR. 

3. Limiting the alkali content of the concrete mixture – 3 kg/m3 alkalis in concrete 

can be a limit for potentially reactive aggregate where aggregate reactivity is 

defined as (i) reactive when expansion is greater than 0.20% at 14 days, and 

potentially reactive when it is between 0.10% and 0.20% at 14 days according to 

ASTM C 1260 test method. 

4. Use supplementary cementing materials. 

(a) Fly ash replacement: 30% to 35% fly ash replacement by mass of cement is an 

effective way to reduce expansion due to ASR. The reaction can be slowed down 

to the point where it will prevent ASR for the design life of a concrete pavement. 

However, reduction in expansion due to fly ash incorporation varies with 

aggregate type, class and chemical composition of fly ash, especially the alkali 

content, and amount of fly ash replacement. In general higher the amount of fly 

ash replacement, the better the effect of controlling expansion. Higher the 

pozzolanic activity of fly ash, the higher the preventive effect on ASR provided 

fly ash does not contribute any extra alkali. Reduction in expansion incorporating 

class F fly ash, regardless of the replacement percentage, is higher than that of 

class C fly ash. Increasing the level of replacement of fly ash or slag can produce 

greater reduction in expansion, but may lead to poor resistance to deicer salt 

scaling. The use of an appropriately proportioned ternary mix results in a marked 

reduction in expansion equal to, or greater than influences of a single 

supplementary cementing material. Pessimum effect of fly ash to control ASR 

possibly does not exist. 

(b) Silica fume: The addition of 10% silica fume by mass of cement can completely 

suppress ASR, possibly because of reduction in OH–

 concentration. 

(c) Ternary blend cement with appropriate proportions of fly ash, slag or silica fume 

in combination causes a marked reduction in expansion due to ASR that exceeds 

the influence of a single supplementary cementing material. 

(d) Use lithium nitrate: Lithium is the lightest metal in the elemental periodic table, 

with an atomic number of 3, atomic weight of 6.94, and density of 0.53 g/cm3

(about half that of water). It is a naturally occurring substance and is a silverywhite metal, slightly harder than sodium, but softer than lead. Lithium nitrate 
AC 150/5380-8 2/2/04 

Appendix 1 

 

5-2 

(LiNO3) is the most effective form of Li used in mitigation of ASR. When 

lithium is used, although silica gel is still formed, the gel remains innocuous, i.e., 

it does not cause cracking. There are two aspects of mitigating ASR with the use 

of lithium compounds in concrete, i.e., (a) prevent expansion by adding lithium 

compound in new concrete and (b) mitigate further expansion in concrete that has 

already been affected by ASR. 

5.2 Lithium use in new concrete

When a concrete is designed to last 50-75 years or more, incorporation of lithium in the 

mixture to prevent the future occurrence of ASR can be beneficial. The alkali content of 

cement in a concrete mixture determines the dosage of lithium nitrate that needs to be 

incorporated. The standard dose is 0.55 gallons of lithium per pound of alkali per unit of 

concrete. The minimum dosage of lithium should be based on aggregate reactivity tested 

according to the modified ASTM C 1260 method. The effect of lithium in reducing ASR 

expansion cannot be tested by the standard ASTM C 1260 method by adding lithium in 

the mortar mix, because lithium leaches out in the 1N NaOH solution. The sodium in the 

soak solution swamps the amount of lithium necessary. To overcome this problem, 

lithium is added to the soak solution at levels to match the alkali equivalent (Na2Oeq). 

Standard dose of lithium present in most commonly used lithium-bearing compounds are 

(1) LiNO3 - 30% LiNO3 in solution, and (2) lithia glass –the dose is based on Li/Na 

molar ratio. 100% lithia glass dose represents the amount of glass that supplies 0.74 

Li/Na molar ratio. The lithium content is calculated from lithia or LiO2 concentration in 

glass, and sodium from the Na2Oeq of the cement. 

Lithia glass is a new type of solid admixture now commercially available. It is basically 

glass made from a mixture of recycled soda-lime glass and lithium. Lithium is added to 

the glass, and the mixture is re-melted. The resulting glass is then ground to a fine 

powder suitable for use as a supplementary cementing material. The glass is formulated 

to react in the concrete over a period of time, that is, slowly release lithium into the 

cementitious system. Typically, the dosage of lithia glass is 1.85 kg per cubic yard of 

concrete. 

Lithia glass in combination with other supplementary cementing materials (especially fly 

ash) has demonstrated expansion lower than either lithia glass or fly ash alone in the 

laboratory. These combinations have suppressed ASR expansion to a very low level. 

The combined use of lithium and supplementary cementing materials is recommended for 

economic reasons and for improving concrete quality. 

5.3 Mitigation of ASR in existing concrete 

Lithium is effective in controlling further expansion in concrete structures with existing 

ASR and, therefore, can extend the service life of the ASR affected concrete. The 

effectiveness of lithium treatment depends on the depth of penetration. The following are 

the common application methods for treating ASR affected concrete. 
2/2/04 AC 150/5380-8 

 Appendix 1 

5-3 

1. Electrochemical chloride extraction, 

2. Topical application, such as ponding and spraying 

3. Vacuum impregnation, and 

4. Pressure injection 

However, the dosage and application technique may vary according to conditions such as 

extent of damage and type of structure. In case of airfield pavements, the most practical 

methods of application are (a) topical application, such as ponding and spraying, (b) 

vacuum permeation, and (c) pressure injection. These methods are briefly described 

below. 

Spray Application. This is most common for flatwork such as pavements, and bridge 

decks. Tests will have to be performed on the spray rate, which can be varied from 3.0 to 

4.5 gal/1,000ft2

, and the soak time required. Additionally, the effect of multiple passes 

needs to be evaluated. This of course can increase the total amount of lithium nitrate 

required from 3.0 to 9.0 gal/1,000ft2. 

Ponding. The pavement structure needs to be ponded with lithium nitrate solution so as 

to maintain contact with the structure for at least 24 hours to get sufficient penetration 

into the surface. 

Vacuum Permeation. This is a fairly recent and distinctive technology, which was 

originally developed in Europe. The basic process has been used in North America since 

1985. Unlike pressure injection, the vacuum permeation process withdraws air and 

moisture from cracks and pores prior to impregnation of the repair solution or resin, 

which in this case will be lithium nitrate. The tendency for the damaged structure to 

burst, so characteristic of conventional pressure injection methods, can be eliminated by 

the vacuum permeation process. Some of the possible advantages of this process include 

the removal of residual moisture, and stress concentrations at the ends of cracks. The 

process can be expected to eliminate the internal damages caused by induced high 

pressures that normally arise when using pressure injection techniques. 

Pressure injection – The principle of this method is the same as that for injecting grout or 

slurry through cracks. This method is not recommended if structural integrity has been 

severely compromised due to advanced ASR, as the pressure applied to inject the lithium 

solution is likely to cause the structure to burst open. 

Another method in existence is electrochemical chloride extraction. This method was 

originally developed to remove chloride and thus reduce corrosion. However, the process 

can trigger ASR by introducing alkalis if the aggregate is reactive. The use of lithium in 

the electrolyte prevents ASR and therefore, the method is applicable to ASR remediation. 

Lithium ions can prevent ASR, regardless of the pH, at high dosages. However, this 

method may not very economical for airfield pavements. 

2/2/04 AC 150/5380-8 

 Appendix 1 

6-1 

Chapter 6: References and Further Reading 

ASTM C 441-89, 1989: Standard test method for effectiveness of mineral admixtures or 

ground blast-furnace slag in preventing excessive expansion of concrete due to 

alkali-silica reaction. Philadelphia. 

ASTM C 227-90, 1990: Standard test method for potential alkali reactivity of cementaggregate combinations (mortar-bar method). Philadelphia. 

ASTM C 295-90, 1990: Standard guide for petrographic examination of aggregates for 

concrete. Philadelphia. 

ASTM C289-94, 1994: Standard test method for potential alkali-silica reactivity of 

aggregates (chemical method). Philadelphia. 

ASTM C 1260-94, 1994: Standard test method for potential alkali reactivity of 

aggregates (mortar-bar method). Philadelphia. 

ASTM C 1293-01, 2001: Standard test method for concrete aggregates by determination 

of length change of concrete due to alkali silica reaction. Philadelphia. 

ASTM 5340-98, 1998: Chapter 7. Airport Pavement Condition Index Surveys 1982 

AASHTO T 303, 1996. Accelerated detection of potentially deleterious expansion of 

mortar bars due to alkali-silica reaction, AASHTO Standard Specifications for 

Transportation Materials and Methods of Sampling and Testing. Nineteenth 

Edition, 1998. 

DeMerchant, D.P., Fournier, B., and Malhotra V.M., 1995. Alkali-aggregate 

reactivity in New Brunswick, Canada – New Brunswick cooperation agreement 

on mineral development, CANMET. 

FHWA-SHRP showcase, 1995. Workshop on alkali-silica reactivity in highway 

Structures. U.S. Department of Transportation, Federal Aviation Administration. 

Publication No. FHWA-SA-95-039. 

Helmuth, R. “Alkali-silica reactivity: An overview of research”, 1998. SHRP-C-342, 

Strategic Highway Research Program, National Research Council, Washington, 

D.C. 
AC 150/5380-8 2/2/04 

Appendix 1 

 

6-2 

Helmuth, R., Stark, D., and Diamond, S., 1992. Alkali-silica reactivity in concrete: an 

overview of research, SHRP Report C/FR-92-000, Part II, pp. 3-6. 

Johnston, D.P., Surdahl, R., and Stokes, D.B., 2000. A case study of a lithium-based 

treatment of an ASR-affected pavement. Proceedings of the 11th International 

Alkali-Aggregate Reaction (B. Fournier Ed.), Quebec, pp. 1149-1158. 

Langley, W.S., and Fournier, B., 1993. Alkali-aggregate reactivity in Nova Scotia. 

 Canada -Nova Scotia cooperation agreement on mineral development, CANMET. 

Paver Concrete Distress Manual. Pavement distress identification guide for jointed 

concrete roads and parking lots. US Army Corps of Engineers, Construction 

Engineering Research Laboratories, TR 97/105, June, 1997. 

Shehata M.H., and Thomas M.D.A., 2002. Use of ternary blends containing silica fume 

and fly ash to suppress expansion due to alkali-silica reaction in concrete, Cem. 

Concr. Res. 32, pp. 341-349. 

Stark, D., Morgan, B., Okarnoto, P., and Diamond, S., 1993. Eliminating or minimizing 

alkali-silica reactivity. SHRP-C-343, Strategic Highway Research Program, 

National Research Council, Washington, D.C., 266 p. 

Stark D., 1993. Eliminating or minimizing alkali-silica reactivity, SHRP Report C-343, 

National Research Council, Washington D.C. 

Stark, D., 1991. “Handbook for identification of alkali-silica reactivity in highway 

structures.” SHRP-C-315, Strategic Highway Research Program. National 

Research Council, Washington, D.C. 

Stokes, D.B., Thomas, M.D.A., and Shashiprakash, S.G., 2000. “Development of a 

lithium-based material for decreasing ASR-induced expansion in hardened 

concrete,” Proceedings of the 11th International Conference on Alkali-Aggregate 

Reaction in Concrete (B. Fournier Ed.), Quebec, pp. 1079-1087. 
2/2/04 AC 150/5380-8 

 Appendix 1 

7-1 

Chapter 7: Test Methods for ASR

ASTM C 289: Standard test method for potential alkali-silica reactivity of aggregates 

(chemical method). 

 

This method is a quick chemical test to estimate potential reactivity of siliceous aggregate. This 

test identifies highly reactive aggregates fairly rapidly and is useful for initial screening of 

aggregate. 

Drawbacks: This test fails to identify slowly reactive aggregates. Certain aggregates produce a 

high amount of soluble silica in this test but do not necessarily produce expansion in service. 

The test does not always give reliable results and cannot be used to test carbonate rocks. 

ASTM C 227: Standard test method for potential alkali reactivity of cement-aggregate 

combinations (mortar-bar method). 

This is a useful method for testing ASR susceptibility of cement-aggregate combinations. It 

measures expansion of mortars made with the test aggregate. Aggregate should conform to 

standard grading. Longer testing periods are preferred for differentiating reactivity of aggregate. 

Drawbacks: Unless highly reactive aggregates are tested, meaningful results require one year or 

more. Even after a long testing period, not all deleterious aggregates exhibit expansive behavior. 

Sometimes this method fails to distinguish between slowly reacting and innocuous aggregates. 

ASTM C 295: Standard guide for petrographic examination of aggregates for concrete. 

This method is a comparatively quick way to predict aggregate reactivity based on microscopic 

examination of aggregate samples. Mineral properties in aggregate determine aggregate 

reactivity. This method is used as a screening method for aggregates. Correlating petrographic 

analysis of aggregate with service record in concrete can derive useful information. 

Drawbacks: This method does not give any quantitative information about aggregate’s actual 

behavior in concrete and is time consuming. Results will not reveal if an aggregate will cause 

deleterious expansion in concrete. 
AC 150/5380-8 2/2/04 

Appendix 1

7-2 

ASTM C 441: Standard test method for effectiveness of mineral admixtures or slag in 

preventing excessive expansion of concrete due to alkali-silica reaction. 

This method is based on expansion developed in mortar bars and uses a combination of cement, 

mineral admixtures, and a reactive crushed Pyrex glass. The method can be used for preliminary 

screening to evaluate the relative effectiveness of different materials used to prevent excessive 

expansion due to ASR. 

Drawbacks: This method is considered unsatisfactory because Pyrex is highly reactive and may 

contain significant levels of alkalis. Moreover, it is not adaptable for testing aggregates from 

different sources, since it is mainly a test for cement ASR reactivity. 

ASTM C 1260: Standard test method for potential alkali reactivity of aggregates (mortar-bar 

method). 

This is one of the most commonly used test methods for assessing the potential reactivity of 

aggregates. Expansion data of mortar can be obtained within as little as 16 days. The test 

method was developed because of the shortcomings of ASTM C 227 and ASTM C 289. This 

method, however, does not replace lengthier test methods. 

Drawbacks: Severe test conditions are applied which do not conform to field conditions. 

Aggregates with good field track records and no history of ASR can sometimes be classified as 

reactive when tested according to this method. 

ASTM C 1293: Standard test method for concrete aggregates by determination of length 

change of concrete due to alkali silica reaction. 

This method measures expansion of concrete prisms made with the coarse and fine aggregates in 

question. Total alkali content of concrete should be 5.25 kg/m3

. 

Drawbacks: This method involves cement-aggregate combinations and requires up to one year 

to complete. 

 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-1 

Chapter 8: Dilatometer ⎯ A Rapid Method for Testing Reactivity of 

As-Received Aggregates

8.1 Introduction 

The undesirable expansion of concrete due to reaction between alkali and certain types of 

reactive siliceous aggregates, known as alkali silica reaction (ASR) continues to be a detriment 

to the long-term performance of airfield pavements. Recent interest to minimize distress 

resulting from ASR has culminated in a need to predict concrete aggregate’s behavior relative to 

ASR expansion. 

A testing apparatus called “dilatometer” has been developed to test alkali reactivity potential of 

concrete aggregates. The dilatometer is instrumented to monitor the volumetric expansion of 

siliceous gel produced by ASR of aggregate placed in it within a relatively short period of time. 

Various aspects of the proposed test procedure were explored with comprehensive laboratory 

tests related to aggregate type, temperature, and normality of test solution. A clear distinction 

between reactive, potentially reactive, and non-reactive aggregates can be made in less than 30 

hours using this method. Furthermore, it also enables one to predict the dosage of lithium 

nitrate, which is now being used as an ASR mitigating agent, needed for a particular aggregate to 

control expansion due to ASR. Based on the test results, it is anticipated that this test method 

will be useful for predicting ASR potential of aggregates from a wide range of sources in 

different parts of the country that are used in concrete for the construction of airfield pavements. 

Alkali-silica reaction occurs in concrete when alkalis from the cement, or from other 

sources, react with free silica present in certain aggregates to form alkali-silica gel. This has the 

property of absorbing water and expanding. This expansion can cause the aggregate particles 

and the cement paste to crack, and this can ultimately damage the concrete [1, 2]. 

The two current methods for identifying potential for ASR in aggregates are ASTM C 

295 petrographic method [3] and ASTM C 289 chemical method [4]. While the former is 

considered strictly a screening method, the criticism of ASTM C 289 method is that some 
AC 150/5380-8 2/2/04 

Appendix 1

8-2

aggregates produce soluble silica, which does not necessarily produce expansion in concrete, and 

therefore, the method is not capable of predicting the behavior of aggregate in terms of potential 

ASR damage. 

Another test method, ASTM C 441 [5] which is a mortar bar test using Pyrex glass, is 

considered unsatisfactory because Pyrex is highly reactive and contains significant levels of 

alkali. Moreover, it is not adaptable for testing aggregates from different sources since it is 

mainly a test for cement ASR reactivity. 

The ASTM C 1260, Test Method for Potential Alkali Reactivity of Aggregates (MortarBar Method) [6], is one of the most commonly used methods, because expansion data of mortar 

can be obtained within as little as 16 days. The test measures the potential aggregate reactivity. 

However, aggregates with good field track record and no history of ASR can sometimes be 

classified as reactive when tested according to ASTM C 1260 method. 

Stark [7] had suggested improvement of ASTM C 1260 test by varying the concentration 

of the NaOH solution to match the pore solution of concrete. By varying concentrations of 

NaOH solution, the test could then determine safe cement or concrete alkali levels for a 

particular aggregate. 

The concept of the new rapid test method is based on measuring the expansion produced 

by siliceous gel when siliceous aggregate reacts with alkali. The procedure is relatively rapid, 

and is able to reliably discriminate between innocuous, potentially reactive, and highly reactive 

aggregates. 

8.2 Experimental 

Test device

The apparatus referred to as dilatometer, is illustrated in Figure 8-1. It consists of a 

stainless steel cylindrical container, a Teflon-coated brass lid, a hollow tower installed on the lid, 

and a float. The inner surface of the lid is configured at a certain angle so that air bubbles can be 

easily removed. The device is prepared by placing the aggregate sample and NaOH test solution 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-3 

LVDT

tower

thermocouple

float

lid

aggregate

container

147

data acquisition system

147

Figure 8-1. Test equipment showing the principal parts, such as container, linear variable 

differential transducer (LVDT), float, and tower 

in the container. More NaOH solution is either filled or excess amount removed through the 

portholes positioned in the cavity of the tower such that the float is able to move on the surface 

of the solution within the tower. 

A LVDT is positioned in the tower with its core connected to the float to measure the rise of the 

NaOH solution surface. Electrical signals from the LVDT are generated as the core moves. The 

signals are acquired and amplified by a signal conditioner and then recorded by a computerized 

data acquisition system. The system yields the accuracy necessary to measure minute volume 

change as noted by changes in the NaOH solution surface in the tower. A guide rod installed 

above the core of the LVDT keeps the float vertically aligned. A thermocouple is installed 

inside the container to monitor temperature in the container. The temperature is recorded by the 

same data acquisition system that records the LVDT signal. Simultaneous recording of the 

expansion due to formation of ASR gel and temperature makes it possible to consider both time 

and temperature effects. The container is placed in a water bath and heated to the desired 

temperature, where it is kept constant, and expansion is recorded continuously for 15 to 30 hours, 

as the case may be. 
AC 150/5380-8 2/2/04 

Appendix 1

8-4

Test procedure

Aggregate is placed in the chamber in a dry condition and then NaOH solution at room 

temperature is added in the container. The lid is securely screwed on and sealed to the container. 

This is important as the equipment is highly sensitive even to minor volume change, and 

therefore even a small leak can adversely affect the test. 

A vacuum is applied for a short period of time to remove entrapped air between 

aggregates. The container is also shaken periodically to facilitate removal of entrapped air. 

After vacuuming, the prepared dilatometer is placed in a water bath in which the water 

temperature is first equilibrated to room temperature. Then the tower access port is opened to 

drain any excess solution. The core of the LVDT with the guide rod is inserted, and the float is 

positioned on the surface of the NaOH solution. If necessary, more NaOH solution is added in 

the cavity of the tower until the float is positioned properly. 

The water bath is heated to the desired temperature, where it is held constant. As ASR 

expansion of aggregate inside the specimen chamber begins, the float rises, and LVDT signals 

are recorded by the computerized data acquisition system. The volume of aggregates used and 

test solution are kept constant for each test. The test is terminated arbitrarily at 20 or 30 hours. 

However, it can be run for longer periods. The exact length of test period has not been decided 

yet. Additional research is required to establish this criterion. 

The chemical compositions of these aggregates are given in Table 8-1. Chemical 

analysis of aggregates shows very little difference in chemical composition. Although variation 

in SiO2 in the three aggregates is minimal, it is the non-reactive aggregate, which contains the 

highest amount of non-siliceous constituents. Actually, the reactivity of an aggregate needs to be 

evaluated by an experienced petrographer, not from its chemical make-up alone. The 

mineralogy of the aggregates was established from X-ray diffraction (XRD) analysis. Quartz 

was identified as the principal mineral, with small amounts of calcite, microcline feldspar and 

other silicate minerals present. This confirmed the chemical analysis results that yielded over 

90% SiO2. 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-5 

 

(a) Undulatory extinction of quartz grains (b) Straight extinction of non-reactive 

in reactive aggregate 

Figure 8-2. Reactive aggregate and non-reactive aggregate 

Table 8-1. Chemical composition of aggregate 

Type Chemical 

Composition Reactive Aggregate Potentially Reactive 

Aggregate 

Non-reactive 

Aggregate 

SiO2 95.67 94.92 93.15 

Al2O3 0.37 0.85 0.33 

Fe2O3 0.68 0.84 0.42 

CaO 1.98 1.96 2.46 

MgO 0.12 0.14 0.08 

 

Na2O 0.64 0.66 1.40 

K2O 0.22 0.35 0.23 

TiO2 0.04 0.06 0.05 

MnO2 0.04 0.04 0.02 

SO3 0.03 0.06 0.06 

Optical properties of these aggregates studied using a polarizing light microscopy [3] 

indicated that both reactive and potentially reactive aggregate consists mainly of strained quartz 

with undulatory extinction (Figure 8-2a), a characteristic optical property considered to be 
AC 150/5380-8 2/2/04 

Appendix 1

8-6

indicative of possible ASR under appropriate conditions. The non-reactive aggregate, on the 

other hand, was composed of quartz grains with straight extinction (Figure 8-2b), suggestive of 

its non-reactivity in the presence of alkalis. Distinction between reactive and potentially reactive 

quartz could not be made from petrographic examination. 

Tests have now demonstrated that several lithium salts can mitigate expansion due to 

ASR [8]. Among these, LiNO3 has been identified as the most soluble one in water [9], and 

therefore, is beginning to emerge as a candidate material for controlling ASR in concrete [10]. 

The IN solution used contains 40.0g of NaOH dissolved in 900 mL of water, diluted with 

additional distilled water to obtain 1.0 L of solution. A 1.0 ± 0.01 N sodium hydroxide (NaOH) 

solution is prepared and standardized to ± 0.001 N. A 0.5N solution can also be prepared to 

evaluate effect of lower normality of alkaline solution on ASR. In order to investigate the effect 

of LiNO3 in controlling expansion due to ASR, 4.6 liters of LiNO3 per 1 kg of Na2O in the 

mixture was added to the test solution [11]. 

8.3 Test results and discussion 

Expansion-age relationship

The fine aggregates used for this research had previously been classified as reactive, 

potentially reactive and non-reactive aggregates, according to ASTM C 1260. The siliceous sand 

classified as reactive aggregate had an expansion of 0.24% at 14 days, while expansion of the 

potentially reactive aggregate was 0.19% at 14 days, and that of the non-reactive sand was only 

0.08% at 14 days. The expansion results are given in Figure 8-3. 

Figure 8-4 shows aggregate expansion due to ASR during the first 30-hour period. 

Reactive aggregate produces higher expansion than that of potentially reactive aggregate and 

non-reactive aggregate, irrespective of temperature, although difference in SiO2 content among 

the three aggregates is marginal. This implies that besides the proportion of SiO2, other inherent 

properties contribute to the expansion. It must be recognized that in this test method the 

expansion produced due to ASR gel and not amount of soluble silica produced, is measured. 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-7 

From these results, it emerges that this new test method can distinguish between gel-producing 

aggregate and expansive gel-producing aggregate within a short period of time. The cut-off 

period is still in experimentation, and may change subject to analysis of additional data. 

In the same figure expansion of aggregate at 80oC is higher than that recorded at 70oC 

and 60oC, irrespective of normality of alkali solution. Increasing the test temperature accelerates 

ASR, especially for highly reactive aggregate. The initial reaction caused by a high temperature 

condition seems to induce the formation of ASR gel and leads to larger overall expansion. This 

suggests that the initial expansion rate at an elevated temperature is more prominent than at 

lower temperature. 

Comparative evaluation of aggregate expansion results for two different normalities is 

given in Figure 8-5. Reactive aggregate immersed in 1N NaOH solution shows higher expansion 

than in 0.5N NaOH solution at a given temperature and age. This suggests that normality of 

alkaline solution also plays a predominant role in the expansion characteristics. Lowering the 

concentration of NaOH results in decreased expansion. 

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0 5 10 15

Time, Days

Expansion, %

Reactive Aggregate

Potentially Reactive Aggregate

Non Reactive Aggregate

Figure 8-3. Expansion curves of aggregate at 14 days 
AC 150/5380-8 2/2/04 

Appendix 1

8-8

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

(a) Reactive aggregate 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

P-reactive aggr. 80C

P-reactive aggr. 70C

P-reactive aggr. 60C

 (b) Potentially reactive aggregate 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Non-reactive aggr. 80C

Non-reactive aggr. 70C

Non-reactive aggr. 60C

(c) Non-reactive aggregate 

Figure 8-4. Effect of operating temperature on development of ASR expansion 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-9 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

(a) Aggregate in 1N NaOH (b) Aggregate in 0.5N NaOH 

Figure 8-5. Expansion of reactive aggregate in 1N and 0.5N NaOH solution 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Non-reactive aggr. 80C

Non-reactive aggr. 70C

Non-reactive aggr. 60C

(a) Reactive aggregate (b) Non-reactive aggregate 

Figure 8-6. Expansion of reactive and non-reactive aggregate in 0.25N NaOH solution
AC 150/5380-8 2/2/04 

Appendix 1

8-10

Figure 8-6 shows the results of expansion for reactive and non-reactive aggregates in 

0.25N NaOH solution. Expansion was much too low, and is beyond proper interpretation, 

regardless of aggregate reactivity and operating temperature. It appears that concentration of 

0.25N NaOH is not adequate to achieve the level of alkalinity required to initiate ASR. It 

appears that a significantly longer testing period is needed if this device is to be used with 0.25N 

NaOH solution. 

Effect of Lithium Nitrate (LiNO3)

The effect of lithium nitrate (LiNO3) on expansion due to ASR illustrated in Figure 8-7 

demonstrates that expansion is dramatically reduced in the presence of LiNO3 even for 1N NaOH 

solution at all the three operating temperatures. Although ASTM C 1260 test method is used to 

test the effectiveness of LiNO3 in controlling ASR expansion, this new rapid test method can be 

used to predict the dosage of LiNO3 required for a particular aggregate. The amount of LiNO3

used in the test solution was based on the results of Touma et al [11]. 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive aggr. 80C

Reactive aggr. 70C

Reactive aggr. 60C

(a) Without LiNO3 solution (b) Within LiNO3 solution 

Figure 8-7. Effect of lithium nitrate on ASR expansion of reactive aggregate at three 

different operating temperatures
2/2/04 AC 150/5380-8 

 Appendix 1 

8-11 

Effect of Calcium Hydroxide, Ca(OH)2

Figure 8-8 shows the effect of introducing calcium hydroxide, Ca(OH)2 in the system, 

since it is considered to be an integral constituent of ASR. For reactive aggregate under 

condition of 1N NaOH at 80oC, a very steep increase of expansion was observed up to 4 hours 

for both reactive aggregate and reactive aggregate adding 1N Ca(OH)2 at 80oC. After 4 hours, 

the slop of the expansion is fairly constant over period of time, but further expansion is possible 

beyond 15 hours. In addition, reactive aggregates immersed in the solution mixing 1N NaOH 

solution with1N Ca(OH)2 solution expanded much more than the reactive aggregate containing 

no Ca(OH)2 after 4 hours. 

Repeatability 

Repeating the tests tested the validity of dilatometer method. Figure 8-9 shows the 

results of three sets of tests performed on reactive aggregate under condition of 1N NaOH at 

80oC. Expansion curves of all sets were fairly similar over testing period. Expansion of the 

aggregate in the third test was slightly higher than that of the first and second testing, but the 

difference is nominal. 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

Reactive Aggr. 80C

Reactive Aggr. 80C w ith 1N Ca(OH)2

Figure 8-8. Effect of calcium hydroxide on ASR expansion of reactive aggregate
AC 150/5380-8 2/2/04 

Appendix 1

8-12

8.4 Conclusions

Advantages of this method 

• This is a rapid method. This test represents an entirely new concept to ASR testing in 

less than 30 hours. The minimum period is still being experimentally determined and 

may change subject to analysis of additional data. 

• This is the only method that measures expansion produced by the gel and not the amount 

of soluble silica produced. It is possible to distinguish between expansive gel-producing 

aggregate and soluble silica-producing aggregate. 

• As-received aggregate can be tested and does not require crushing as in several standard 

tests. Therefore, the effect of specific surface area on aggregate reactivity is eliminated. 

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 5 10 15 20 25

Time (hours)

Expansion (%)

1st-Reactive aggr. 80C

2nd-Reactive aggr. 80C

3rd-Reactive aggr. 80C

Figure 8-9. Repeatability of dilatometer test
2/2/04 AC 150/5380-8 

 Appendix 1 

8-13 

• The large chamber dimensions can accommodate all aggregate size ranges commonly 

used in concrete. 

• This method can measure the effectiveness of LiNO3

 as a mitigating compound. 

Although the ASTM C 1260 test method is used to test the effectiveness of LiNO3 in 

reducing ASR expansion, the new rapid method can be used to predict the dosage of 

LiNO3 required for a particular aggregate. 

• Test results have not yet been calibrated against any other standard test method. This test 

method should be capable of assessing the expansion of cement mortar. It may be useful 

to correlate one of the existing accelerated test methods in practice and this new 

dilatometer method. 

Using the dilatometer to measure expansion of ASR gel represents an entirely new 

approach to test ASR potential of aggregates in less than 30 hours. This method measures 

expansion produced by the ASR gel, not the amount of soluble silica. It is possible to distinguish 

between expansive gel-producing aggregate and soluble silica producing aggregate. 

The effectiveness of LiNO3 as a mitigating agent of ASR was also evaluated by the 

dilatometer method. The results indicate that the Dosage of LiNO3 can be predicted for a 

particular aggregate. The new method provided test results very rapidly without sacrificing 

reliability. Since the dilatometer method uses bulk aggregate samples, it eliminates the effect of 

the specific surface area. Further studies are anticipated for comparing the dilatometer method 

with other standard tests, and for determining the optimal dosage of LiNO3 required for a 

particular aggregate. 
AC 150/5380-8 2/2/04 

Appendix 1

8-14

8.5 References

1. Helmuth, R., Stark, D. and Diamond, S., “Alkali-Silica reactivity in Concrete—An 

Overview of Research, SHRP Report C/FR-92-000, Part II, 1992, pp.3-6. 

2. Johansen, V.C., Klemm, W.A., and Taylor, P.C., “Why Chemistry Matters in Concrete,” 

Concrete International. Vol.24, 2002, pp.84-89. 

3. ASTM C 295, Guide for Petrographic Examination of Aggregates for Concrete, Annual 

Book of ASTM Standards, American Society for Testing and Materials, Philadelphia, 

1999, pp. 175-182 

4. ASTM C 289, Standard Test Method for Potential Alkali-Silica Reactivity of Aggregates 

(Chemical Method)1

, Annual Book of ASTM Standards, American Society for Testing and 

Materials, Philadelphia, 1999, pp. 156-162 

5. ASTM C 441, Standard Test Method for Effectiveness of Mineral Admixture or Ground 

Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Alkali-Silica 

Reaction1

, Annual Book of ASTM Standards, American Society for Testing and Materials, 

Philadelphia, 1999, pp. 225-227 

6. ASTM C 1260, Standard Test Method for Potential Alkali Reactivity of Aggregates 

(Mortar-Bar Method, D), Annual Book of ASTM Standards, American Society for Testing 

and Materials, Philadelphia, 1999, pp. 646-649. 

7. Stark D., “Eliminating or Minimizing Alkali-Silica Reactivity,” SHRP-C-343, Strategic 

Highway Research Program, National Research Council. Washington, DC, 1993. 

8. Stark, D.C., “Lithium Salt Admixture-An Alternative Method to Prevent Expansive AlkaliSilica Reactivity,” PCA Research and Development Information, Skokie, 1992. 

9. Stokes, D.B., “Use of Lithium to Combat Alkali Silica Reactivity,” Proceedings of the 10th

International Conference on Alkali-Aggregate Reaction in Concrete, Sydney, 1996, pp.862-

867. 

10. Johnston, D.P., Surdahl, R., and Stokes, D.B., “A Case Study of A Lithium-Based 

Treatment of an Alkali-Affected Pavement,” Proceedings of the 11th International 

Conference on Alkali-Aggregate Reaction in Concrete, Quebec City, 2000, pp.1149-1158. 
2/2/04 AC 150/5380-8 

 Appendix 1 

8-15 

11. Touma, W.E., Fowler, D.F., and Carrasquillo, R.L., “Alkali-Silica Reaction in Portland 

Cement Concrete-Testing Methods and Mitigation Alternatives,” Research Report ICAR 

301-1F, International Center for Aggregate Research, 2001.