The potential for alkali silica reaction (ASR) has been investigated through dissolution tests and the determination of the concentration of elemental 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 delivered to the solution by the cement, although lower concentrations were released by both the aggregates and fly ash. Silica was released into solution according to aggregate reactivity. Rapid and local release of silica can yield an expansive ASR gel for reactive aggregate. Fly ash was observed to release silica rapidly indicating that the primary action of 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 main source of solution silica for the reactive aggregate
