Experimental and statistical analysis of the alkali-silica reaction of accelerating admixtures in shotcrete

This study investigated the alkali-silica reaction of accelerating admixtures for shotcrete. Tests were performed with two types of cement (low- and high-alkali) and three types of accelerating admixture (alkali-free, cement-based mineral and aluminate). An expansion test was performed to determine the alkali-silica reactivity according to ASTM C 1260. The results showed that the expansion increased with the total equivalent alkali content of the specimens. To examine this finding statistically, analyses were conducted at the 95% confidence level. When the low-alkali cement was used, no difference appeared to exist in the expansion after a reasonable period of time regardless of the accelerating admixture. In contrast, when the high-alkali cement was applied, the expansion of the specimens varied with time, although no difference was observed between the expansions of the plain sample and the specimen using the alkali-free accelerating admixture. (C) 2011 Elsevier Ltd. All rights reserved.