Corrosion performance of hot-dip galvanized zinc-aluminum coated steel rebars in comparison to the conventional pure zinc coated rebars in concrete environment

Abstract

In this investigation zinc was alloyed with aluminum in order to improve the corrosion resistance of hot-dip galvanized coated steel rebars in contact with chloride-contaminated concrete. To rapidly assess the role of aluminum alloying in zinc, test panels in sheet form containing 10%, 15%, 20%, and 30% aluminum in zinc were prepared and evaluated in terms of their corrosion resistance via salt spray exposure tests. It was found that 10%Al-90%Zn (10AZ) provided the best results. Mild steel rebars were galvanized in 90%Zn-10%Al and 100%Zn (100Z) baths and their corrosion resistance performances when they were exposed to simulated concrete pore solution and embedded in mortars were examined. The10AZ-coated rebar showed superior corrosion resistance performance to the 100Z-coated rebar. Electrochemical impedance spectroscopy, DC polarization, scanning electron microscopy, Raman spectroscopy, and X-ray diffraction techniques were used to study the kinetics and corrosion mechanism of the coated rebars.