Title: Efficiency of Fly Ash in Mitigating Alkali-Silica Reaction Based on Chemical Composition

Author(s): L. Javier Malvar and Lary R. Lenke

Publication: Materials Journal

Volume: 103

Issue: 5

Appears on pages(s): 319-326

Keywords: admixtures; alkali-silica reaction; durability; fly ash

DOI: 10.14359/18153

Date: 9/1/2006

Abstract:
While recent specifications address alkali-silica reaction (ASR) prevention using recycled products, such as fly ashes, as cement replacement, the restrictions on the ashes may be too conservative. Data from previous research studies were used to assess the effectiveness of fly ashes in preventing ASR based on their chemical composition, the composition of the cement, and the reactivity of the aggregates. A chemical index was derived to characterize the fly ash and cement based on their chemical constituents. For the fly ashes, this index correlated well with ASTM C 618 and CSA A3001 classifications. This index was also used to assess the efficiency of ashes that did not meet either specification. For a given ash, cement, and aggregate reactivity, it was possible to derive the minimum cement replacement that is needed to ensure, with 90% reliability, that the 14-day ASTM C 1260 expansion would remain below 0.08%.