Original Paper(Vol.62 No.8 pp.498-503)

An Assessment on Mitigating Effect of ASR in Fly Ash-Bearing Mortars with Andesite Stones by ASTM C 1260

Shinichi HIRONO and Kazuyuki TORII

Abstract:Volcanic rocks such as andesite have popularly been used for aggregates in the Hokuriku District. Therefore, the andesitic aggregates have contributed to a steady occurrence of alkali-silika reaction(ASR) in concrete. Taking into account the effective utilization of local materials, so-called gChisan-chishoh, both the reduction in the environmental impact and the rationalization of natural resources, positive countermeasures for mitigating ASR by using blended cements with fly ash(FA) or blast-furnace slag(BFS) are most expected. This paper examines the mitigating effects of mineral admixtures on ASR of mortars by the accelerated mortar-bar test(ASTM C 1260). As the result of test, the replacement with FA or BFS at normal percentages recommended by JIS A 5308 decreased significantly the expansion of mortar bars using reactive andesitic aggregates in the Noto peninsula. Especially, a high-quality fine FA produced in the Hokuriku District is hopeful in its practical use of concrete mixtures. Furthermore the ASR mitigating effects by mineral admixtures are assessed with a good performance by the test method gASTM C 1260h.

Key Words:Alkali-silica reaction, Mitigating effect, Fly ash, ASTM C 1260, Petrographic examination