Influence of calcination temperature of industrial by-product gypsum on sulphoaluminate cement-based grouting material

To enhance the resource utilization of industrial solid waste and promote the low-carbon and sustainable development of mining industry, an eco-friendly sulphoaluminate cement-based grouting material (EFSC) was prepared using industrial by-product gypsum (IPG), sulphoaluminate cement clinker and lime as raw materials. The effects of IPG calcined at different temperatures on working properties, compressive strength and microstructure characteristics of EFSC were investigated. Furthermore, the mechanical properties of the cemented specimens were evaluated using RMT and SEM in the grouting reinforcement experiment. Results showed that with the increase of IPG calcination temperature, the setting time and fluidity of EFSC were reduced. The expansion rate and compressive strength showed a positive correlation with IPG calcination temperature. Especially when the calcination temperature reached 700 degrees C, its compressive strength was 14.5 MPa at 6 h, which was 27.62 times that of the control group. Microscopic characterizations confirmed that the calcined IPG contributed to the formation of anhydrite in EFSC. Meanwhile, a large number of AFt and amorphous hydration products formed a dense network structure, improving the matrix density. In the grouting reinforcement test, the mechanical load-bearing capacity and plastic deformation of the coal gangue cemented specimens were improved significantly at IPG calcination temperatures of 700 degrees C and 800 degrees C, with compressive strength increasing by 59.70 % and 71.82 %. The excellent mechanical performance could be attributed to the interface bonding property caused by needle-like AFt. This study provides innovative insights into the use of industrial solid waste as a partial replacement for cementing materials, which is expected to promote the sustainable development of green mining.