Corrosion resistance and corrosion interface characteristics of Cr-alloyed rebar based on accelerated corrosion testing with impressed current

This study investigates corrosion resistance and corrosion interface characteristics of novel Cr-alloyed steel rebar in mortar using electrochemical measurements, X-ray computed tomography (X-CT) scanning, and X-ray photoelectron spectroscope (XPS) analysis. Impressed constant current corrosion (ICCC) test was performed on alloyed steel rebar-mortar (ASRM) sample and carbon-steel rebar-mortar (CSRM) sample in a chloride-contaminated environment. After 5 days of ICCC test, alloyed steel rebar suffered a certain degree of localized corrosion with limited corrosion product, while the carbon-steel rebar presented severe general corrosion. Electrochemical tests demonstrated that the ASRM sample exhibited more than ten times in Rct value of the electrochemical impedance spectroscopy test and only about 0.46% in corrosion current density of the potentiodynamic polarization test compared to the CSRM sample. The above results revealed the excellent passivation performance and corrosion resistance of the ASRM sample, which is attributed to the formation of the stable composite passive film containing Cr/Fe oxides and hydroxides.