Evaluation of properties of chamotte particle-reinforced geopolymer composites in high-temperature applications

In this research, the microstructural and mechanical characteristics of metakaolin-based geopolymer reinforced with chamotte particles was investigated at room temperature and after exposure to high temperatures (600–1200 °C). The flexural strength and the appearance of the samples indicated the effective presence of chamotte particles as a reinforcement within the matrix of geopolymer. This was due to crack control in the composite and enhanced volume stability. The connection between chamotte particles and geopolymer binder boosted the flexural strength to 22.15 ± 1.37 MPa at room temperature. Heated composite samples at 800 °C showed improved mechanical performance of the thermally stable chamotte aggregates. However, leucite crystallization at 1000 °C caused volume instability and upon elevating temperature to 1200 °C, leucite peak intensity was more pronounced, which was responsible for the reduction of the strength in the composite. As a result, leucite phase formation in the matrix changed the connection behavior to the fragile state and the particles departed the matrix at high temperatures. The results of this research revealed good compatibility between the geopolymer matrix and chamotte particles for producing low-cost castable refractories up to 800 °C.