Alkali-Silica Reaction in Concrete with Previously Inert Aggregates

Abstract

Alkali-silica reaction (ASR) is a persistent issue and has evaded eradication for nearly 80 years. The problem stems from a lack of standardized testing of aggregates. Cases occur when changes in material properties lead to potentially reactive aggregates reacting with higher alkali cements. A research program was established at the University of Arkansas to investigate cases of ASR, which occurred in combination with previously inert aggregates. In addition, locally available fly ashes were evaluated to determine replacement rates required to minimize the risk of ASR. A field monitoring program was established to evaluate deterioration mechanisms and mitigation measures. A concrete barrier wall located near the University of Arkansas was diagnosed with ASR that had considerable variation in the damage between sections of the wall. Deterioration ranges from minimal visible deterioration to severe damage or complete failure. The testing program reveals that certain aggregates that were previously deemed safe for use in concrete reacted deleteriously when other material properties changed.