Preparation of Low-Carbon Ferroaluminate Cement with High Iron Red Mud and Multi-Solid Wastes: Mineral Phase Optimization and Hydration Mechanism.

The large-scale accumulation of industrial solid wastes has caused serious environmental concerns, while the traditional cement industry urgently requires low-carbon alternatives to reduce CO2 emissions. In this study, a solid waste-based ferroaluminate cement (SWFAC) was successfully prepared using high iron red mud (HIRM) and multi-solid wastes. The effects of calcination temperature, holding time, and raw material composition on clinker mineral evolution were systematically investigated, and the relationship among mineral composition, mechanical properties, and hydration behavior was further elucidated. The results demonstrated that increasing the calcination temperature promoted the formation of C4A3$, C2S, and C4AF, while highly reactive alumina facilitated clinker formation. The optimized SWFAC clinker exhibited a balanced mineral assemblage with high contents of C4A3$ and C4AF, resulting in excellent mechanical performance. Increasing HIRM content regulated the Fe-bearing phase formation and improved the long-term stability of the cement matrix. Hydration mechanism investigations revealed that the formation of AFt, AFm, AH3, and Fe-AFt hydration products facilitated the progressive refinement and densification of the cement matrix, thereby promoting the development and long-term enhancement of compressive strength. This work provides a feasible strategy for the synergistic utilization of industrial solid wastes and the development of low-carbon ferroaluminate cement.