Assessing the role of standard test methods in alkali content threshold determination for ASR reactive aggregates

Accelerated test methods have long and successfully been used to assess and categorise the reactivity of aggregates to the alkali-silica reaction (ASR). Test methods (e.g. RILEM AAR-3.2) have also been developed to assess the potential for alkali content threshold determination for aggregates that have been categorised as reactive and to investigate the efficacy of supplementary cementitious materials (SCMs) in mitigating ASR (e.g. RILEM AAR-10). Typically, these tests are based on the concrete prism test (CPT). The CPT is, however, susceptible to leaching of the alkali from the prisms. As testing alkali threshold content or SCM efficacy is dependent on the alkali content of the concrete prism, alkali leaching has the potential for providing misleading results. This study reports the outcomes of threshold testing using CPT as well as the use of a novel pore solution immersion test method for their assessment of threshold determination and SCM efficacy in mitigation of ASR for a course reactive aggregate.