Review on characteristics of metakaolin-based geopolymer and fast setting

The setting of metakaolin-based geopolymer depends on the raw materials and mix proportions. Setting, when material is cured at room temperature, takes about 1 day and is longer than setting time of Portland cement. For the fast setting of geopolymers, some studies increased the curing temperature or used raw materials with high CaO content. Also, Ca2+ and Mg2+ compounds were used as additives. Setting can be easily controlled and accelerated by adding Ca2+ compounds. However, it has been reported that knowledge of the reaction mechanism and final products between Ca2+ and geopolymers is still limited. In this study, we investigated the characteristics of metakaolin-based geopolymers and methods for fast setting of geopolymers, and made hypotheses about the reaction mechanism between Ca2+ and geopolymers.