Effect of coarse aggregate grading on the ASR expansion and damage of concrete

Assessment of alkali-silica reactivity is an important quality control measure for concrete aggregates in preventing alkali-silica reaction (ASR) in concrete structures. However, the reactivity is often assessed, by the concrete prism test as specified in ASTM C1293, for a particular grading of coarse aggregate that may deviate from the aggregate grading in field concrete. This study investigated the effects of coarse aggregate grading on the ASR expansion and damage of concrete. The results indicated that a deviation of 10% in the grading of reactive coarse aggregate could result in up to 50% larger concrete expansion compared to concrete with standard (ASTM C1293) grading. Aggregate grading also significantly influenced the ASR damage of concrete as measured by the damage rating index method. Furthermore, aggregate grading influenced the quality of concrete. Aggregate grading remains an important parameter in the study of the reactivity of aggregates and the ASR performance of concrete.