Improved corrosion resistance of reinforcing steel in mortars containing red mud after long-term exposure to aggressive environments

The influence of red mud (RM) on long-term corrosion resistance of reinforcing steel in mortars exposed to coupled actions of chloride attack and natural carbonation was evaluated in this study. Moreover, the pore structure and hydration products of RM mortar with 20 wt% red mud were compared with those of ordinary Portland cement (OPC) mortar. Compared with OPC mortar, the higher electrical resistivity of RM mortar during the long-term exposure to aggressive environments delayed the penetration of chloride ions and the diffusion of oxygen, therefore providing an effective protection for the embedded steel. In addition, owing to the possible filling effect of CaCO3, the natural carbonation of RM mortar was unexpectedly beneficial for improving the corrosion resistance of steel by facilitating the formation of a compact steel-mortar interface.

Automated summary

This study evaluated the influence of red mud on the long-term corrosion resistance of reinforcing steel in mortars exposed to chloride attack and natural carbonation. The higher electrical resistivity of red mud mortar delayed the penetration of chloride ions and the diffusion of oxygen, providing effective protection for the embedded steel. Additionally, the natural carbonation of red mud mortar facilitated the formation of a compact steel-mortar interface, improving the corrosion resistance of the steel.