Reactive Aggregate Powder Used as Filler to Mitigate ASR

Alkali-Silica Reaction (ASR) is a deterioration mechanism in concrete that produces an expansive gel causing expansion and disruption. The conventional approach to mitigate the harmful effects of ASR involves incorporating supplementary cementing materials (SCMs) in the concrete mix. SCMs foster a pozzolanic reaction which reduces the available alkalis in pore solution, one of the ASR reactants. However, the current limited availability of SCMs mandates the identification of alternatives capable of effectively preventing ASR-induced damage. This study explores the use of finely crushed reactive aggregate as pozzolans to reduce or prevent ASR. Three different siliceous aggregates were pulverized to two particle sizes: (i) passing 75 µm, and (ii) passing 45 µm. The pulverized aggregate powder replaced 15% (by mass) of the non-reactive sand in concrete samples. The expansion of these samples was evaluated using the Concrete Prism Test as per CSA A23.2–14. The aggregate powders were used with General Use Cement (GU), General Use Portland Limestone Cement (GUL), and silica fume Portland cement (containing 8% silica fume) to identify the efficacy of the powder with the three types of cement. The preliminary results showed some powder to be more effective than others; however, powder alone was not enough to stop the reaction.