Alkali-aggregate reaction — the reaction that occurs over time between highly alkaline cement paste and noncrystalline silicon dioxide — can lead to a loss of concrete strength. A new ASTM International standard provides guidance on how to address the potential for such deleterious reactions in concrete construction. The new standard is ASTM C1778, Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete.

“C1778 guides a user on how to properly identify if an aggregate is reactive and provides a prescriptive and performance based approach for the user to follow to mitigate the reaction,” says ASTM member Thano Drimalas, research associate, University of Texas at Austin.

Concrete and material engineers, contractors and concrete ready-mix companies are among those who will use ASTM C1778 to determine if alkali-aggregate reaction is going to be a problem in a particular batch of concrete.

According to its scope, ASTM C1778 will address the process of identifying both potentially alkali-silica reactive and alkali-carbonate reactive aggregates through standardized testing procedures. In addition, C1778 provides a selection of mitigation options available to minimize the risk of expansion when alkali-silica reactive aggregates are used in concrete construction.

ASTM C1778 was developed by Subcommittee C09.50 on Risk Management for Alkali Aggregate Reactions, part of Committee C09 on Concrete and Concrete Aggregates.

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