An Experimental Study on Mitigating Alkali Silica Reaction by Using Fly Ash (FA) in Combination with Silica Fume and Expanded Perlite Powder (EPP)
ASR suppression by FA, SF, EPP, FA in combination with SF and EPP were evaluated by both mortar bar and concrete prism test. Mortar bars were made based on JIS A 1146, meanwhile concrete prism bars were casted in accordance with Rilem AAR-3. Both specimens were stored in 40°C 100% R.H. controlled room. Mortar and concrete mixtures used reactive aggregate in pessimum proportion. The results indicated that FA in combination with SF and EPP showed smaller expansion compared to FA. The best of concrete mixtures in reducing expansion is combination of FA with SF (FA15SF10).
Effectiveness of mineral admixtures in reducing ASR expansion
Abstract This paper investigates the effectiveness of eight mineral admixtures in reducing the alkali silica(te) reactivity of cement mortar. The admixtures include one class F fly ash, a condensed silica fume, a ground fiberglass, three glass containing waste materials, and two inert fillers (carbon and calcium carbonate). Mortar bar expansion, the change in evaporable water content, the evidence of reaction and the composition of reaction products were studied. It was found that shale is the only reactive component of the sand and the effectiveness of admixtures in reducing alkali-silica reaction depends largely on the chemical composition of the admixtures. Ground fiberglass is very effective in controlling the alkali silica reaction, while inert fillers have only a “dilution effect”. It is thought that admixtures reduce ASR expansion by two reactions: (1) pozzolanic reaction that reduces the permeability of concrete and entraps some fraction of the alkali ions; (2) alkali silica reaction that consumes most of the available alkali ions and thereby prevents the reaction between alkalis and aggregate.
Study of silica-lime solution reactions
Abstract A thorough study of the reactions between amorphous silica and lime solutions of variable concentration shows a steady and continuous change in the progress of these silica-lime systems related to the lime content of the solution at time zero. The presence or absence of silica in solution is explained from these results, not by the ease with which silica would go into solution but by the difference in the rate of which silica dissolves and hydrates are formed.