Title: Cracking in Concrete Due to Expansive Reaction Between Aggregate and High-Alkali Cement as Evidenced in Parker Dam
Author(s): H. S. Meissner
Publication: Journal Proceedings
Appears on pages(s): 549-568
Excessive expansion has been recognized for some time as causing that type of concrete distress mani- fested by a characteristic random-pattern cracking. Recent disclosures point to an additional new explanation in the chemical reaction between high-alka- li cement and the mineral constituents of certain ag- gregates. It is possible that many failures, which have been incorrectly interpreted, may ultimately be clari- fied when analyzed for this suspected action. Paper describes a chain of circumstantial evidence which connects one case of deteriorating concrete with this type of action. The cement used was known to have contained large amounts of soda and potash. After considerable research it was discovered that the natural sand and gravel contained small amounts of andesite and rhyolite, which were reacting in the concrete with such cement. Part of the evidence was a gel substance, a by-product of the reaction, identi- fied as sodium silicate.