Experimental study on the properties of CMTs-incorporated geopolymers prepared at low temperatures

Abstract

Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement, fly ash(FA), and kaolin to produce geopolymers, to make full use of CMTs, the properties of geopolymers manufactured under different material mass ratios and curing methods(standard curing, water bath curing, and 60 ℃ curing)are evaluated with significantly increased dosage of CMTs. Porosity and unconfined compressive strength tests, X-ray diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy are used to determine the physical and mechanical properties, microstructure, and mineral composition of geopolymers. Finally, costs and CO₂ emissions of specimens with different material mass ratios during the preparation processes are compared. The results show that during the geopolymerization of low-calcium materials, various geopolymer gels, including calcium silicate, calcium silicoaluminate, and mainly sodium silicoaluminate gels, coexist. The solid waste, cost, and carbon dioxide emission reductions can reach 100%, 166.3 yuan/t, and 73.3 kg/t, respectively. Under a curing condition of 60 ℃, the sample with a CMTs mass fraction of 70% and an FA mass fraction of 30% meets the requirements of porosity, compressive strength. The resource utilization of CMT and FA is realized in a more economical way.