Synergistic Mechanism of Nanoparticles and Corrosion Inhibitors in Electrochemical Repair: Pore Structure Refinement and Chloride Ion Removal of Reinforced Concrete

Abstract

The use of migrating corrosion inhibitors has been recognized by the European Committee for Standardization as an effective method to prevent and control corrosion of steel in concrete. Current research on electrochemical corrosion inhibition technology primarily focuses on the effects of using inhibitors alone on the performance of reinforced concrete. To explore the impact of combined electrochemical treatment with nanoparticles and corrosion inhibitors, this paper selects nano-Fe3O4 and an undecyl hydroxyethyl imidazoline quaternary ammonium salt inhibitor (M) for the electrochemical treatment of concrete specimens. Through methods such as potential polarization curve analysis, weight-loss testing, and scanning electron microscopy, the effects of nano-Fe3O4 and inhibitor M on the corrosion resistance and bond performance of reinforced concrete after electrification were analyzed. Additionally, the influence of their synergistic effects on the microstructure and hydration products of reinforced concrete was investigated. The results demonstrate that the combined action of nanomaterials and inhibitors can repair the passive film of steel bars, significantly reduce the corrosion rate of steel bars, and expel approximately 73% of the free chloride ions from the surfaces of the steel bars. Furthermore, the combined action of nanomaterials and inhibitors effectively enhances the bond performance of chloride-contaminated concrete, with a bond strength increase of 7.2–12.8% compared with that of using inhibitors alone. Mercury intrusion and microstructure analysis reveal that the hydration products generated by the combined action of nanoparticles and inhibitors are uniformly dispersed within the concrete, contributing to a refined pore structure. During the electrochemical repair process, the combined action of nanoparticles and inhibitors significantly enhances the corrosion resistance of the reinforced concrete and improves the internal pore structure.