Characterization of cost-effective green engineered magnesium oxysulfide cement-based composites (MOSC-ECC) prepared by replacing MgO in magnesium oxysulfate cement with slag

A cost-effective green engineered magnesium oxysulfide cement-based composites (MOSC-ECC) which was prepared with magnesium oxysulfate cement (MOSC) and large-volume solid waste (slag) in this paper. The macro and micro mechanical properties, thermal conductivity, water resistance, evolution of hydration products and microstructure of MOSC-ECC were studied. The energy consumption, carbon emissions, and cost of MOSCECC were calculated and compared with traditional ECC. Test results showed that adding slag instead of lightburned MgO can increase the strain-hardening strength and energy indices of MOSC-ECC, and improve the ductility. In addition, the incorporation of slag lowered the proportion of 5Mg(OH)2 & sdot;MgSO4 & sdot;7 H2O phase (517 phase), led to a decrease in the strength, density and thermal conductivity of the MOSC-ECC. Compared with traditional OPC-based ECCs, the prepared MOSC-ECC showed a reduction in embodied energy by approximately 32 %, a reduction in CO2 emission of around 60 %, and a reduction in material costs more than 38 %. Therefore, slag can be used as the main component of MOSC-ECC, and the dosage can be up to 50 % by weight of MgO, which has obvious economic and environmental benefits.