Performance optimization and carbon reduction effect of solid waste-based cementitious materials from iron and steel metallurgical slags and ammonia-soda residue

The utilization of solid waste as a resource is a beneficial approach to achieve pollution reduction and carbon reduction simultaneously. In this paper, we developed a quaternary solid waste-based cementitious materials (SWCMs) that can be used as a substitute for cement by utilizing four types of solid waste, namely ground granulated blast furnace slag (GGBS), steel slag (SS), ammonia-soda residue (ASR) and desulfurization gypsum (DG). The performance optimization and carbon emissions of SWCMs are investigated by response surface methodology and emission factor calculations. The results showed that a second-order polynomial model can accurately predict the compressive strength of mortar specimens of SWCMs, with prediction accuracies of 96.78 % and 87.17 % for compressive strengths at 3 days and 28 days, respectively. In terms of raw materials, DG content positively correlates with the compressive strength of the mortar containing SWCMs, moreover, ratios of GGBS to ASR of less than two or more than eight are beneficial. In addition, the production process of each ton of SWCMs emits 71.51 kg CO₂, which is only 10 % of the production process of ordinary Portland cement. Overall, this work elucidates the influence of raw materials on the mechanical properties of quaternary SWCMs and quantifies their carbon reduction effects as a substitute for traditional cement, advancing the investigation and application of SWCMs in the realm of low-carbon materials.