Paper Title
Dissolution Phenomenon of Geopolymer in Water

Abstract
Lightweight geopolymers containing 50 wt.% of Si sludge were fabricated by using integrated gasification combined cycle slag, and were immersed in water to evaluate their stability under immersed conditions. The geopolymers that were cured for less than 14 days dissolved in water during an immersion period of 1 day, and their compressive strength only reached up to 63% of that of the specimens that were not immersed. In addition, the geopolymers that were cured for more than 21 days did not dissolve in water during the immersion period of 1 day, and their compressive strength was approximately same as that of the specimens that were not immersed. Thus, it is concluded that the geopolymerization of the specimen completes only after curing for 21 days, and the specimens that undergo complete geopolymerization are stable in water even though they contain a high percentage of Si sludge. The completion of geopolymerization can be estimated using the results of the pH change in water during immersion, comparison of compressive strength before and after immersion, and morphology changes after immersion at different curing periods. Keywords - Lightweight Geopolymer, IGCC Slag, Si Sludge, Dissolution