Protection against reinforcement corrosion using various hydroxy acid-based rust converters: tests in mortar medium

This study investigates the protective effect of various hydroxy acid-based rust converters such as malic acid, tartaric acid, lactic acid, hydroxy acid mixture and glycolic acid in controlling the corrosion of steel reinforcement embedded in cement mortar. The steel rebars pre-treated with hydroxy acids were embedded in cement mortar samples. Afterward, the reinforced samples were exposed to 2.5% sodium chloride (NaCl) and 2.5% magnesium sulphate (MgSO4) solution for 52 weeks (similar to 365 days). The corrosion state of rebars was estimated in terms of visual assessment of steel rebars, electrical resistivity (ER), corrosion current density based on linear polarisation resistance (LPR) and half-cell potential (HCP) values. The results indicate that the rebar specimens treated with malic, tartaric, lactic and hydroxy acid mixture underwent a lower degree of corrosion-related deterioration. This inhibition effect on the corrosion of steel rebars is due to the formation of insoluble complexes and chelates, leading to the preservation of hydration products in the samples collected from the steel-mortar interface as evidenced by SEM, XRD and FTIR spectroscopy.