Investigation of ASR Reactivity through Slurry Dissolution Tests
Author: Roboredo, C., Thomas, P., Boyd-Weetman, B., Vessalas, K., Farah, D., and Sirivivatnanon, V.
Type: Conference Paper, Concrete 2019, Sydney, Australia.
ASR; Silica & Alkali Dissolution; Mitigation; Reactive and Non-Reactive Aggregate; Fly Ash.
The Alkali Silica Reaction (ASR) is investigated through the dissolution and determination of concentration of elements species, Na, K, Ca and Si in the supernatant fluid of GP cement, aggregate and fly ash slurries. The aggregates selected for investigation were a reactive greywacke and a non-reactive micro-diorite both of which contain quartz. Alkali ions were primarily delivered to a solution by the cement, although lower concentrations were released by both aggregated and fly ash which may be of concern in the delayed deleterious ASR. Silica was released in to solution according to aggregate reactivity. Rapid local release of silica can yield an expansive ASR gel for reactive aggregates. Fly ash was also observed to release silica rapidly indicating that the primary action of the fly ash is through a competitive reaction for the formation of silica gel thus mitigating deleterious ASR. Quartz content as determined by x-ray diffraction analysis indicated that this phase was the source of solution silica for the reactive aggregate.