Study on the Effect of the Quality of Fly Ash for Controlling Alkali-Aggregate Reactions


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Title: Study on the Effect of the Quality of Fly Ash for Controlling Alkali-Aggregate Reactions

Author(s): S. Kobayashi, Y. Hozumi, T. Nakano, and T. Yanagida

Publication: Special Publication

Volume: 114


Appears on pages(s): 403-416

Keywords: alkali-aggregate reactions; alkalies; cements; concretes; expansion; fly ash; mortars (material); Materials Research

Date: 5/1/1989

Paper presents the results of the tests conducted on reactive andesite produced to determine if Japanese fly ashes produced in Japan have an effect in controlling the alkali-aggregate reactions in concrete. Fourteen fly ashes produced were subjected to Japan Industrial Standard (JIS) alkali-silica reaction (ASR) mortar bar test (40 x 40 x 160 mm, alkali content in cement 1.2 percent, s/a = 2.25) with (c + f) ranging from 5 to 30 percent. With f/(c + f) at 20 percent or higher, all the mortar test bars incorporating fly ash had little expansion even after 6 months, but with f/(c + f) at 10 percent, different expansions were produced depending on the type used. The analysis of the data indicated that the component Na2Oeq of fly ash would accelerate the expansion while the component SiO2 will restrain the expansion. The controlling ability is also related to the alkali content of the cement: the greater the alkali from the cement and fly ash, the greater the quantity of fly ash required for preventing the expansion. An empirical formula expressing such a relationship has been derived. 123-389