ALKALI AGGREGATE REACTIONS IN CONCRETE

Abstract

Alkali aggregate reaction (AAR) may cause deterioration in concrete when alkaline solutions attack certain siliceous aggregates. This article describes signs of the trouble, including cracking in concrete and weeping of gel from cracks. AAR depends upon sufficient alkali, a reactive aggregate and adequate mositure. Low alkali cements are considered, and rock types found to be reactive. Reference is made to tests for aggregates, and the vulnerability to attack of certain structures due to the presence of water. The article concludes with possible precautions against this type of failure. (TRRL)