Performance of Composite Corrosion Inhibitors in Carbonated Concrete

This study aims to evaluate the corrosion inhibition performance of different types of inhibitors for steel reinforcement in cement paste under accelerated carbonation conditions. Electrochemical methods, including electrochemical impedance spectroscopy EIS, linear polarization resistance LPR, and open-circuit potential OCP measurements, were utilized on specimens with various inhibitor formulations during exposure to a high-CO2 environment. The results indicate that composite inhibitors provide the greatest protection, significantly outperforming single-component anodic or cathodic inhibitors. Among anodic inhibitors, sodium molybdate showed more effective corrosion inhibition than sodium chromate, and among cathodic inhibitors, BTA was more effective than DMEA, as evidenced by higher polarization resistance and more stable passivation. After 120 days of carbonation, the specimen with the optimal composite inhibitor remained passive with a low corrosion rate and a relatively noble steel potential, whereas the uninhibited specimen exhibited active corrosion.