Effects of Chemical Composition of Ca(OH)2 and Precursors on the Properties of Fast-Curing Geopolymers

Geopolymer is an alumina silicate-based ceramic material that has good heat-resistance and fire-resistance; it can be cured at room temperature, and thus its manufacturing process is simple. Geopolymer can be used as a reinforcement or floor finish for high-speed curing applications. In this manuscript, we investigate a high-speed curing geopolymer achieved by adding calcium to augment the curing rate. Metakaolin is used as the main raw material, and aqueous solutions of KOH and K2SiO3 are used as the activators. As a result of optimizing the high bending strength as a target factor for geopolymers with SiO2/Al2O3 ratio of 4.1 similar to 4.8, the optimum ranges of the active agent are found to be 0.1 <= K2O/SiO2 <= 0.4 and 10 <= H2O/K2O <= 32.5, and the optimum range of the curing accelerator is found to be 0.82 <= Ca (OH)(2)/Al2O3 <= 2.87. The maximum flexural strength is found to be 1.35 MPa at Ca (OH)(2)/Al2O3 = 2.82, K2O/SiO2 = 0.3, and H2O/K2O = 11.3. The physical and thermal properties are analyzed to validate the applicability of these materials as industrial insulating parts or repairing finishing materials in construction.