ACI PRC-225.1-20: Removal of Optional Alkali Limit in Standard Specifications for Portland Cement

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Alkali-silica reactivity (ASR) is a potentially deleterious expansive reaction between alkalies in the pore solution of concrete and certain reactive aggregates. When ASR was first identified as a distress mechanism in the 1940s, cements with equivalent alkali contents below 0.60 percent by mass were shown to reduce the risk of this reaction. Subsequent research has shown that limiting the cement alkali content to 0.60 percent is not always sufficient to control deleterious ASR with every aggregate nor in all concrete mixtures. It is now well accepted that the reactivity of the aggregate and the amount of alkalies available in the concrete are more important in predicting deleterious ASR than cement alkali content alone.




Document Details

Author: ACI Committee 225

Pages: 3


Categories: Aggregates

Formats: Protected PDF/Web View

Table of Contents




Specification changes

Role of alkalies in cement and concrete

Controlling ASR




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