Alkali-Silica Reaction Mitigation: State of the Art and Recommendations

Abstract

Alkali-silica reaction (ASR) mitigation techniques from various states in the U.S., and from various countries and international organizations, were assessed and summarized. A set of recommended mitigation procedures were developed requiring not only use of low-alkali cement, but replacement of part of it by Class F fly ash (or Class N pozzolan, 25-40% by weight), or ground granulated blast-furnace slag (GGBFS), Grade 100 or 120 (40-50% by weight), or a combination of both. The Class F fly ash should also have a maximum of 1.5% available alkali, maximum 6% loss on ignition, and a maximum of 8% CaO. A modified ASTM C 1260 using the actual mixture is recommended for ASR testing. In addition, to mitigating ASR, these recommendations are expected to: 1) reduce concrete costs; 2) enhance concrete durability; 3) increase fly ash and GGBFS recycling; and 4) support the 1997 Kyoto Protocol by greatly reducing carbon dioxide production.