Alkali-Silica Reactivity Potential and Mitigation: Test Methods and State of Practice (2023)

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2023 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 1083 Alkali-Silica Reactivity Potential and Mitigation TEST METHODS AND STATE OF PRACTICE ano Drimalas Kevin J. Folliard University of Texas Austin, TX Jason H. Ideker Anuj Parashar Oregon State University Corvallis, OR Michael D. A. omas Ardalan Ghanizadeh Ashlee M. Hossack University of New Brunswick Fredericton, NB Benoit Fournier Laval University Quebec City, QC Subscriber Categories Bridges and Other Structures • Materials • Pavements Research sponsored by the American Association of State Highway and Transportation Ofcials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniques—the National Cooperative Highway Research Program (NCHRP). 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e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. e Board’s varied activities annually engage about 8,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. e program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP RESEARCH REPORT 1083 Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Inam Jawed, Senior Program Officer Mireya Kuskie, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications NCHRP PROJECT 10-103 PANEL Field of Materials and Construction—Area of Specs, Procedures, and Practices Maria Masten, Minnesota Department of Transportation, Maplewood, MN (Chair) Patricia Baer, Pennsylvania Department of Transportation, Harrisburg, PA Ryan Barrett, Kansas Department of Transportation, Topeka, KS Tara L. Cavalline, University of North Carolina, Charlotte, NC D. Stephen Lane, Barboursville, VA Andy Naranjo, Texas Department of Transportation, Austin, TX Karthik H. Obla, National Ready Mixed Concrete Association, Alexandria, VA Prasad Rangaraju, Clemson University, Clemson, SC Paul D. Tennis, Portland Cement Association, Lawrence, KS Robert P. Spragg, FHWA Liaison Nelson H. Gibson, TRB Liaison

AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 10-103, “Improving Guidance of AASHTO R 80/ASTM C1778 for Alkali-Silica Reactivity (ASR) Potential and Mitigation,” by the Department of Civil, Architectural, and Environmental Engineering at the University of Texas at Austin (UT Austin). UT Austin was the contractor for this study, with subcontracts to Oregon State University (OSU) and the University of New Brunswick (UNB). Dr. Thano Drimalas (UT Austin) served as the principal investigator, assisted by the following co-principal investigators: Dr. Kevin Folliard (UT Austin), Dr. Jason H. Ideker (OSU), Dr. Michael D. A. Thomas (UNB), and Dr. Benoit Fournier (Laval University). Additional authors of this final report include Ardalan Ghanizadeh (UNB), Ashlee M. Hossack (UNB), and Dr. Anuj Parashar (OSU). This final project report is dedicated to Dr. Michael D. A. Thomas, who passed away during the preparation of the final project deliverables. Dr. Michael D. A. Thomas Mike Thomas in 2015 at the Treat Island, ME, exposure site

NCHRP Research Report 1083: Alkali-Silica Reactivity Potential and Mitigation: Test Methods and State of Practice provides recommendations to improve currently used test methods for estimating alkali-silica reactivity (ASR) potential in concrete. These recommendations include (1) updates to ASR test methods; (2) guidelines for some promising, recently developed methods to assess aggregate reactivity; and (3) proposed preventive measures. State departments of transportation and others involved in selecting concrete materials for the construction of highway infrastructure will greatly benefit from the findings and recom- mendations of this research. The realistic assessment of ASR and identification of preventive measures remain major challenges to the concrete and aggregate industry. The recently developed AASHTO R 80 practice and the ASTM C1778 guide have significantly improved the assessment of aggre- gates for potential ASR and the selection of appropriate preventive measures to allow the use of potentially reactive aggregates in new concrete construction. However, since these tests are based on concrete mixtures with rather high cement and alkali contents, concerns have been raised that they may not properly represent more realistic mixtures that contain moderate or lower cement and alkali contents. Some recent data have also indicated that the amounts of supplementary cementitious materials (SCMs) recommended by these tests may not adequately control expansion in outdoor exposure blocks that contain large amounts of high-alkali cements. A range of alkali loadings and additional types of SCMs need to be investigated to provide a holistic view of the appropriateness of current test methods as well as the efficacy of preventive measures. Under NCHRP Project 10-103, “Improving Guidance of AASHTO R 80/ASTM C1778 for Alkali-Silica Reactivity (ASR) Potential and Mitigation,” the University of Texas at Aus- tin was tasked to address the present shortcomings of current ASR test methods. The study included a critical review of literature on issues related to various tests used to assess ASR potential in concrete and field performance. Knowledge gaps in the current state of evaluation of field concrete mixtures for ASR potential were identified. Based on the find- ings of the literature review, a test matrix was developed. Field exposure concrete blocks were cast with varying concrete materials and placed in diverse environmental conditions in order to supplement existing information and develop improved benchmarking of cur- rent and recently developed performance tests. Particular attention was given to exposure blocks made with lower cement content and cement alkali loadings. It will take time beyond the scope of this project before any ASR-related impacts on these low-alkali blocks will be noticeable. Therefore, the project team used its historic database of laboratory and exposure F O R E W O R D By Inam Jawed Staff Officer Transportation Research Board

site data to prepare draft language for consideration that will incorporate the results of this research into the next update of AASHTO R 80/ASTM C1778. There are seven appendices supplemental to this report. Along with the ASR exposure blocks database, these can be found on the National Academies Press website (nap.national academies.org) by searching for NCHRP Research Report 1083: Alkali-Silica Reactivity Potential and Mitigation: Test Methods and State of Practice.

Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at nap.nationalacademies.org) retains the color versions. 1 Summary 3 Chapter 1 Background 3 Research Motivation 6 Chapter 2 Research Approach 7 Materials 9 Mixture Proportions 11 Material Testing 16 Laboratory Results for Aggregate Reactivity 20 Aggregate Prevention Results 47 Historical Data 50 Exposure Blocks Results 52 Texas Department of Transportation Exposure Blocks 55 Chapter 3 Findings and Applications 55 Summary of Recommended Changes for Aggregate Reactivity Testing 57 Summary of Recommended Changes for Preventive Measure Testing 61 AASHTO R 80 and ASTM C1778 Summary of Recommended Changes 63 Chapter 4 Conclusions and Suggested Research 63 Outdoor Exposure Blocks 63 Aggregate Reactivity Assessment 63 Preventive Measure Assessment 64 Efficacy of Preventive Measures 64 Suggested Research 65 References 67 Acronyms and Abbreviations 69 Appendices C O N T E N T S