Effect of calcined lithium slag, copper tailings and tungsten tailings on the properties and microstructure of hybrid cements

The effects of desulfurized gypsum (DG) activation on the performance and hydration microstructure of composite materials were investigated, with calcined lithium slag (LS), copper tailings (CT), and tungsten tailings (TT) powders employed as supplementary cementitious materials (SCMs) to substitute 30 wt% of ordinary Portland cement (OPC), either individually or in binary blends. Hydration matrix of the hardened paste was evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and mercury intrusion porosimetry (MIP). The purpose of this work was to reveal the activation paths of weak alkali synergy in combinations, and to establish quantitative criteria for experimental design. The calcined LS and CT supplied reactive SiO 2 and Al 2 O 3 , whereas the calcined TT contributed a substantial quantity of amorphous SiO 2 . The calcination temperature of 850°C was selected to enhance the pozzolanic reactivity of LS, CT, and TT powders. The activation of DG also contributed to the potential strength of composites. The XRD and XPS results exhibited that the amorphous SiO 2 and Al 2 O 3 and the micro particle filling component were also necessary in the synergistic ratio of weak alkali activation. Compared with the samples doped with LS alone, the Si-O and the Si-Al bonds in the Aluminosilicate in the TT were weakened, the Si 2p binding energy measured by XPS decreased from 101.43 eV to 101.79 eV (Δ = − 0.36 eV) and 102.85 eV decreased to 102.44 eV (Δ = − 0.41 eV), respectively. The samples of combination solid wastes also conformed to such a composition ratio, which may contribute to form carboaluminations and ettringite. The XRD and TG test findings demonstrated that the mining solid waste had been activated, and their degree of hydration (DOH) were increasing accordingly. This work proposed a new idea of employing DG as a mild alkali to stimulate the activation of mining solid waste to produce cementitious materials.