Influence of equivalent reactive quartz content on expansion due to alkali silica reaction

In this research, the effect on the reactivity of aggregates containing different quartz crystal sizes (0-10 mu m; 10-60 mu m, 60-130 mu m) has been studied, proposing a unique limit for all of them applied to their weighted sum (Equivalent Reactive Quartz). For this aim, the expansion in mortar bars has been correlated with the content of reactive components, and values of the individual mathematic weights for different crystal sizes have been obtained: 8.3 vol.% of quartz 10-60 mu m; and 2.6 vol.% of quartz <10 mu m (corresponding to 0.1% expansion at 14 days). The results show that 60-130 mu m crystal size of quartz has a negligible effect on the expansion. These individual limits can be reduced to a unique one equal to 2.6 vol.% applied to the Equivalent Reactive Quartz. The use of this concept allows to evaluate the reactivity of aggregates in which there are simultaneously different reactive quartz crystal sizes. (C) 2011 Elsevier Ltd. All rights reserved.