A simple way to mitigate alkali-silica reaction

Abstract

A possible practice to prevent disorders due to alkali-silica reaction (ASR) in concretes containing reactive aggregates is the use of chemical admixtures (lithium salts) or, more commonly, mineral admixtures such as fly ash, silica fume, ground granulated slag or metakaolin. An analysis of the literature concerning ASR revealed some papers devoted to the mitigating activity of reactive aggregate powders (RAP) when associated with their parent aggregates. These RAP result from the grinding of the reactive aggregate. To verify the efficiency of this method of mitigation, tests were performed on concrete prisms cured at 60°C and 100% R.H., using four reactive aggregates, associated or not with their RAP. The results showed that the use of RAP reduced or suppressed ASR-expansion, suppressed surface cracking and counteracted the loss of compressive strength due to ASR. If these findings are confirmed by trials on other types of aggregates, the addition of RAP would be a simple way of avoiding ASR disorders.