Comparative study of corrosion inhibition effect on steel rebars in carbonated concrete-pore-solutions: Tolyltriazole vs. sodium phosphate

Abstract

Concrete structures exposed to carbonated environments are susceptible to steel reinforcement corrosion, leading to structural deterioration and reduced service life. In this research, the effectiveness of two commonly used corrosion inhibitors, tolyltriazole (TTA) and trisodium phosphate (TSP), in carbonated concrete pore (CCP) solutions was compared to enhance the corrosion resistance of steel rebar. The study involved the preparation of simulated carbonated concrete pore solutions to mimic the environment of concrete structures exposed to carbonation. The concrete-pore solutions were simulated by immersing the specimens in a carbonation chamber. Electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) tests were performed to evaluate the corrosion resistance of the steel rebars. The corrosion potential, polarization resistance, and corrosion current density were measured and compared among the different groups. Additionally, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses were conducted to examine the surface morphology, chemical composition and corrosion products formed on the steel rebars. The CCP solution with equal concentrations of TTA and TSP demonstrated the highest corrosion resistance and corrosion inhibition efficiency. TTA and TSP effectively inhibit pitting corrosion of steel in CCP solution, according to SEM, EDS, and XPS analyses. The findings suggested that there is a competitive interaction between phosphate ions and TTA on the steel surface, leading to an antagonistic impact on corrosion inhibition. It was suggested that the [Fen(TTA)p]m complex would produce a protective coating on the surface of steel, which would act as a synergistic inhibitor.