Proposed Guidelines for the Prevention of Alkali-Silica Reaction in New Concrete Structures

Abstract

The approach now under consideration by the Canadian Standards Association’s Technical Group on Alkali-Aggregate Reactions (AARs) to prevent the risk of deterioration associated with the use of potentially reactive aggregates in concrete is described. This approach involves a risk-evaluation process based on three factors judged critical for the development of damage in concrete structures due to alkali-silica reaction. The factors are ( a) the degree of reactivity of the particular reactive aggregate, ( b) the size of the concrete element and the environmental conditions it will face, and ( c) the expected service life of the structure. The proposed preventive action against AARs will depend on the actual risk level thus determined. The action will involve one or a combination of the following approaches: ( a) limit the alkali content in the concrete to a selected level, or ( b) use an effective supplementary cementing material (SCM) (or an effective combination of SCMs) in sufficient amounts.