Plant-Based Corrosion Inhibitors for Reinforced Concrete Under Chloride Attack: Advances, Mechanisms, and Prospects

Chloride-induced steel corrosion is one of the major causes of durability degradation in reinforced concrete (RC) structures. Conventional inhibitors have inherent drawbacks in environmental safety, long-term stability, and cement compatibility. Plant extracts, featuring renewability, biodegradability, and abundant bioactive components, have emerged as promising green corrosion inhibitors. This review summarizes the categories, inhibition mechanisms, and evaluation methods of plant-based inhibitors, and discusses multi-scale characterization and computational techniques for mechanism research. A conceptual Ginkgo biloba extract (EGb)-LDH strategy is discussed as a possible future route for plant-based inhibitor delivery, but its chloride-responsive release and corrosion-protection performance remain to be experimentally verified.