Preparation of iron-rich sulfoaluminate cement by regulating Fe-bearing minerals

Abstract

The Fe-bearing minerals play a critical role in the preparation and performance of iron-rich sulfoaluminate cement (IR-SAC), such as C₄AF and C₄A_3-xF_x $\bar{S}$. In this study, Fe₂O₃ was used to form C₄AF and C₄A_3-xF_x $\bar{S}$ in the preparation of IR-SAC. The mineral formation and mechanical properties of IR-SAC containing C₄AF and C₄A_3-xF_x $\bar{S}$ were investigated. The results indicated that when Fe₂O₃ was used to form C₄AF, the mineral formation of the IR-SAC clinker basically met the design objectives, and more than 91.00 wt% Fe₂O₃ formed C₄AF. The increase in Fe₂O₃ led to an increase in the C₄AF content and a decrease in the C₄A₃ $\bar{S}$ content in the clinkers. When Fe₂O₃ is used to form C₄A_3-xF_x $\bar{S}$, the Fe₂O₃ content that forms C₄A_3-xF_x $\bar{S}$ increases with increasing Fe₂O₃ in the clinkers, and up to 48.23 wt% of Fe₂O₃ forms C₄A_3-xF_x $\bar{S}$. The highest proportion of Fe₂O₃ in C₄A_3-xF_x $\bar{S}$ reaches 19.34 wt%, with an x value of 0.39. From the perspective of mechanical properties, C₄A_3-xF_x $\bar{S}$ contributes more significantly to initial strength development than C₄AF does. Proportion analysis revealed that the preset formation of C₄A_3-xF_x $\bar{S}$ caused insufficient Al₂O₃ content and excessive CaSO₄ content in the system, leading to high sulfate loss and Fe₂O₃ substitution for Al₂O₃. The more obvious the shortage of Al₂O₃, the more severe the sulfate loss and substitution phenomenon. This work has a positive effect on promoting the utilization of Fe₂O₃ in IR-SAC preparation.