chapter  10
Evaluation of the Interfacial Transition Zone in Concrete Affected by Alkali—Silica Reaction
Pages 9

In a similar study, Baker and Poole [5] also observed alkali ions migrating into the opal aggregate from the cement paste. They suggested that calcium silica hydrates (CSH) normally formed during cement hydration may not have completely developed under high alkali concentration in the interfacial zone with opal, thus allowing alkali ions to attack opal and produce the reaction gel.