Dual effects of phytic acid on reinforced low-carbon mortar: Dealkalization of red mud and improvement of corrosion resistance

Abstract

In concrete production, partially replacing ordinary Portland cement (OPC) with red mud (RM) offers environmental and low-carbon benefits while enhancing steel corrosion resistance. However, to mitigate risks of alkali-aggregate reaction (AAR) in concrete, RM requires a pretreatment of dealkalization, especially when it comes to large substitution ratios. Phytic acid (PA), an acidic organic inhibitor, shows promise in effectively reducing the alkalinity of RM. This study explores the use of PA for RM dealkalization before its incorporation as the OPC substitute in reinforced mortars. In addition to the effective dealkalization by PA, the results also demonstrate a synergistic effect between PA and RM in improving the corrosion resistance of steel embedded in mortar. Furthermore, a feasible explanation for this synergistic inhibition is proposed, highlighting the combined roles of PA and RM in protecting steel from chloride-induced corrosion.