Optimizing the design parameters for chamotte particle-reinforced geopolymers

This study delved into the utilization of chamotte particles in varying contents (0–50 wt%) as reinforcing agents in both fresh and hardened states within potassium-based geopolymer (KGP) composites. Although the previous research predominantly underscored the high-temperature stability of chamotte in composites subjected to extreme conditions, this study focuses on expanding their potential applications at ambient temperature. The experimental findings showed that the flowability of the pastes experienced a slight reduction up to 20 wt% chamotte, followed by a substantial decrease, ultimately resulting in complete shape retention at 50 wt%. Squeeze flow and standard rheological tests supported these observations, revealing elevated work-to-squeeze values peaking at 1.3 J. X-ray diffraction data showed that crystallinity prevailed in chamotte, establishing its efficacy as a nonreactive reinforcement. In the hardened state, the inclusion of chamotte enhanced the mechanical properties of the composites, specifically compressive, flexural, and splitting tensile strengths, reaching up to 61.7, 13.2, and 5.6 MPa, respectively. Young's modulus (E) and shear modulus (G) also exhibited an upward trend with increasing chamotte content, reaching values of up to 17.7 and 7.7 GPa at 50 wt%, respectively. Scanning electron microscopy (SEM) analysis validated particle interlocking and crack-bridging mechanisms. In general, this study highlights the effectiveness of chamotte particles in improving the mechanical properties of KGP composites at room temperature. It also emphasizes the necessity of considering the mentioned parameters in the design of particulate-reinforced geopolymer compositions for diverse applications.