Author: Sirivivatnanon, V., Hocking, D., Cheney, K., and Rocker, P.
Type: Conference Paper, Concrete 2019, Sydney, Australia.
Theme: Concrete Durability
The Australian Standards AS 1141.60.1 and AS 1141.60.2 were published in 2014 as Accelerated Mortar Bar Test (AMBT) and Concrete Prism Test (CPT) to determine the potential alkali-silica reactivity (ASR) of aggregates. Both methods were extended to evaluate the effectiveness of supplementary cementitious materials (SCM) in mitigating ASR, similar to ASTM C1567 and CSA A23.2-14A, in a research program undertaken by the Cement, Concrete and Aggregates Australia (CCAA). Eight aggregates were tested with various dosages of either fly ash or slag and expansions measured up to 35 days and 2 years for AMBT and CPT respectively. In addition, the efficacy of SCMs to mitigate ASR was determined for four additional reactive aggregates based on the AMBT. The results were evaluated based on corresponding reactivity criteria in the two Australian Standards. They showed that fly ash or slag can effectively be used to mitigate ASR and that the AMBT provided a more conservative dosage of SCM in mitigation ASR than the CPT. The required fly ash or slag dosages are also found to be consistent with recommendations given in HB79. Most importantly, there are findings from many exposure sites around the world that showed the reliability of AMBT and CPT in predicting the effectiveness of SCM-mitigated solution in long-term field-exposed large concrete blocks.