Influence of pulverized–fuel ash and granulated blastfurnace slag upon expansion caused by the alkali–silica reaction

Abstract

Synopsis The effectiveness of seven pulverized-fuel ashes(pfa) and a ground granulated blastfurnace slag (gbfs) in reducing the expansion and cracking induced in mortar bars by the alkali–silica reaction is described. The proportion of reactive aggregate in the mortar bars was such that the water-soluble alkali to reactive silica ratio lay close to its critical value. It is shown that the partial replacement of a high-alkali cement by either pfa or gbfs reduces the expansion induced by the alkali-silica reaction and that with high-cement-content mixes it is necessary to replace more than 40% of the cement by pfa or gbfs to prevent damage from occurring due to the alkali-silica reaction. It is concluded that both materials act effectively asalkali diluters, gbfs being more effective in reducing damage due to the alkali-silica reaction than pfa.