Depending on the processing conditions, geopolymers can exhibit a wide variety of properties and characteristics. Curing profile serves as a crucial parameter in synthesis of geopolymers. In this paper, the influence of curing temperature and curing time on the properties of kaolin-based geopolymer was studied. The samples were separated into several curing conditions; including curing at ambient temperature, 40°C, 60°C, 80°C and 100°C for 1 day, and up to 3 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Results showed that curing condition has a significant effect on the mechanical properties of kaolin-based geopolymer. Generally, curing at ambient temperature was not feasible, while increase in temperature favored the strength development. In addition, prolonged curing time improved the geopolymerization process, and led to higher strength gain. However, curing at high temperature for a long period of time caused failure of the sample at a later age

In this paper, the thermal performance of ground-granulated blast furnace slag (GGBFS) geopolymers is investigated. The geopolymers were prepared with sodium-based alkali activator and exposed to elevated temperature (200 to 1000°C) after 28 d of curing at room temperature. The unexposed geopolymers exhibited excellent compressive strength of 95 MPa. The compressive strength reduced to 8·9 MPa at 800°C and increased to 19·8 MPa at 1000°C. The strength regained by 122·5% as compared to the residual strength at 800°C. The crack reduction and partial melting in geopolymers treated at 1000°C signifies crack healing at elevated temperature, which in turn increases the compressive strength. In addition, the formation of crystalline phases of gehlenite (Ca₂Al₂SiO), mayenite (Ca₁₂Al₁₄O₃₃) and larnite (Ca₂SiO₄) filled the geopolymer matrix and formed an ordered structure. This further enhanced the strength and high-temperature stability of GGBFS geopolymers.