Mechanical Properties and Pore-Forming Mechanism of Porous Ceramsite Prepared from Multi-Source Granite Solid Waste
Granite mining areas generate large quantities of abandoned soil and rock powder, posing environmental challenges and resource waste. This study investigates the synergistic preparation of porous ceramsite from two typical granite solid wastes—weathered granite soil (high Al2O3) and granite waste rock powder (high SiO2)—with waste glass powder as a fluxing agent. Single-factor experiments and response surface methodology (Box-Behnken) were employed to optimize the process and elucidate the pore-forming mechanism. The optimal conditions were a mass ratio of weathered granite soil:granite waste rock powder:waste glass powder of 5.6:2.4:2, a preheating temperature of 480 °C, a sintering time of 32 min, and a sintering temperature of 1140 °C. Under these conditions, the resulting porous ceramsite achieved a compressive strength of 1.74 MPa. The ceramsite effectively immobilized heavy metals, ensuring environmental safety. This research demonstrates that multi-component complementarity and multi-factor coupling optimization can produce porous ceramsite with favorable mechanical properties and stable pore structure, providing a theoretical basis and technical support for high-value utilization of granite solid waste.