The utilization of wet grinding copper tailing for preparing ultra-high performance concrete

The development of ultra-high performance concrete (UHPC) is constrained by the high consumption and cost of cement. This study examined the feasibility of using wet-ground copper tailings (WGCT) as supplementary cementitious materials to create eco-friendly UHPC by replacing silica fume (SF) and Portland cement (PC). The study evaluated fluidity, compressive strength, autogenous shrinkage, chloride permeability, hydration heat, and microstructure of UHPC with WGCT. The effects of WGCT on the hydration process, mechanical properties, and microstructure development of UHPC were systematically evaluated. Results showed that WGCT could slightly increase the compressive strength when it was used to replace small dosage of PC. Despite increased electric flux with higher WGCT content, WGCT-UHPC maintained low chloride ion penetration. Besides, WGCT initially increased the heat flow peak intensity before a slight decrease, suggesting potential in mitigating shrinkage cracking in hot weather. SEM analysis revealed a denser microstructure, particularly in the bonding area between sand and slurry when WGCT replaces PC. These findings highlighted WGCT as a viable, sustainable substitute for SF or PC in UHPC.