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.

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