ALKALI-AGGREGATE REACTIVITY (AAR) FACTS BOOK 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA-HIF-13-019 4. Title and Subtitle 5. Report Date March 2013 Alkali-Aggregate Reactivity (AAR) Facts Book 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Thomas, M.D.A., Fournier, B., Folliard, K.J. 9. Performing Organization Name and Address 10. Work Unit No. The Transtec Group, Inc. 6111 Balcones Drive Austin, TX 78731 11. Contract or Grant No. DTFH61-06-D-00035 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Office of Pavement Technology Final Report March 2013 Federal Highway Administration 1200 New Jersey Avenue, DE Washington, DC 20590 14. Sponsoring Agency Code 15. Supplementary Notes Contracting Officer’s Representative (COR): Gina Ahlstrom, HIAP-10 16. Abstract This document provides detailed information on alkali-aggregate reactivity (AAR). It primarily discusses alkali-silica reaction (ASR), cover­ ing the chemistry, symptoms, test methods, prevention, specifications, diagnosis and prognosis, and mitigation. Alkali-carbonate reaction (ACR) is also addressed. 17. Key Words 18. Distribution Statement Alkali-silica reactivity, alkali-aggregate reaction, reactive No restrictions. This document is available to the public through the Na­ aggregates, ASR, concrete durability, symptoms, identifica­ tional Technical Information Service, Springfield, VA 22161. tion, prevention, mitigation, lithium 9. Security Classif. (of this 20. Security Classif. (of this 21. No of Pages 22. Price report) page) 211 SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2 *SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003) Table of Contents 1 – Introduction .............................................................................................................................1 1.1 DEFINITIONS.....................................................................................................................1 1.2 HISTORY OF AAR.............................................................................................................2 1.3 AAR TODAY .......................................................................................................................4 REFERENCES ..........................................................................................................................8 2 – Fundamentals of Alkali-Silica Reaction................................................................................9 2.1 INTRODUCTION ...............................................................................................................9 2.2 CHEMISTRY OF THE REACTION ..............................................................................10 2.3 MECHANISM OF EXPANSION ....................................................................................13 2.4 REACTIVE SILICA .........................................................................................................15 2.4.1 Types of Reactive Silica ...............................................................................................15 2.4.2 Effect of Aggregate Size ...............................................................................................18 2.4.3 Pessimum Effect ........................................................................................................... 20 2.5 SOURCES OF ALKALI ...................................................................................................22 2.5.1 Pore Solution Composition ...........................................................................................22 2.5.2 Threshold Alkali Contents ............................................................................................25 2.5.3 Alkali Recycling ........................................................................................................... 27 2.6 ROLE OF MOISTURE.....................................................................................................29 REFERENCES ........................................................................................................................31 3 – Symptoms of Alkali-Silica Reaction (ASR).........................................................................35 3.1 INTRODUCTION .............................................................................................................35 3.2 CRACKING .......................................................................................................................35 3.3 EXPANSION CAUSING MOVEMENTS AND DEFORMATIONS...........................40 3.4 POP-OUTS .........................................................................................................................43 3.5 SURFACE DEPOSITS (GEL EXUDATION VS. EFFLORESCENCE).....................45 REFERENCES ........................................................................................................................46 4 – Test Methods..........................................................................................................................47 4.1 INTRODUCTION .............................................................................................................47 4.2 ASR TEST METHODS FOR EVALUATING AGGREGATE REACTIVTY ...........47 4.2.1 ASTM C 295: Standard Guide for Petrographic Examination of Aggregates for Con­ crete........................................................................................................................................ 48 4.2.2 ASTM C 289: Standard Test Method for Potential Alkali-Silica Reactivity of Aggre­ gates (Chemical Method) ....................................................................................................... 50 4.2.3 ASTM C 227: Standard Test Method for Potential Alkali Reactivity of Cement- Aggregate Combinations (Mortar-Bar Method) .................................................................... 51 4.2.4 AASHTO T 303 (ASTM C 1260): Standard Test Method for Potential Alkali Reactiv­ ity of Aggregates (Mortar-Bar Method) ................................................................................ 51 4.2.5 ASTM C 1293: Standard Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction ................................................... 54 4.3 ASR TEST METHODS FOR EVALUATING PREVENTIVE MEASURES ............ 58 4.3.1 ASTM C 441: Standard Test Method for Effectiveness of Mineral Admixtures or Ground Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Al­ kali-Silica Reaction ................................................................................................................ 59 4.3.2 ASTM C 1567: Standard Test Method for Determining the Potential Alkali-Silica Re­ activity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method).................................................................................................................................. 61 4.3.3 ASTM C 1293: Standard Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction ................................................... 63 4.3.4 Other ASR Test Methods.............................................................................................. 64 4.4 ACR TEST METHODS FOR EVALUATING AGGREGATE REACTIVITY......... 66 4.5 SUMMARY.......................................................................................................................