In-depth insight into the cementitious synergistic effect of steel slag and red mud on the properties of composite cementitious materials

Abstract

The low activity of steel slag (SS) and the high alkalinity of red mud (RM) severely limit their resource utilization in cementitious materials. In this study, SS, RM and desulfurized gypsum (DG) were used to prepare composite cementitious materials. The experimental results proved that the synergistic effect of SS and RM improves the mechanical properties of high-volume solid waste cementitious materials. The cementitious synergistic effect of SS and RM was studied, and it was found that the alkali in RM and sulfate in DG could stimulate the activity of SS, generating more C–S–H gel and ettringite in the matrix after curing for 3 days. In the presence of 5% DG, the interaction between SS and RM significantly increases the overall hydration degree of composite binders, leading to an increase in hydration product contents and densification of the microstructure. Novel findings about the cementitious synergistic effect of SS and RM provide innovative guidance for the synergistic utilization of multiple solid wastes in composite cementitious materials.