Chemistry of alkali-silica reaction

In pozzolanic reaction, the alkali silicate gel is formed in an environment rich in Ca and, except in a narrow zone close to the reacting surface, is quickly converted into C-S-H. In ASR, it is formed in an environment poor in Ca , and massive outflows of gel may result. The cement paste cannot supply Ca fast enough to prevent much of this gel from persisting for long 

A rapid chemical test for the susceptibility of aggregates to ASR has been described (Ml22). The chemistry on which it is based is confused (D55). 

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