Insights into the corrosion resistance of Cr-Mo alloy reinforcing steel in simulated pore solution and real seawater sea-sand concrete: A preliminary study

Corrosion of steel bars embedded in reinforced concrete structures considerably reduces the service life and even causes early failure of the structure. The purpose of this study is to investigate the corrosion resistance mechanism of Cr-Mo alloy reinforcing steel (CR) in seawater sea-sand concrete (SWSSC) and the possibility of its application in SWSSC. Three types of steel were carried out in real SWSSC and seawater sea-sand concrete pore solution (SWSSCPS). Compared with low-carbon steel (LC) and stain-less steel (SS), electrochemical measurements, AFM, XPS and SEM-EDS were applied to study the composition, structure and morphology characterizations of passive film. Electrochemical analysis revealed that in the initial stage of immersion, the corrosion resistance of CR demonstrated a rapid increase in open-circuit potential and electrochemical impedance spectroscopy (EIS), suggesting an active-passive transition process. The passive film on CR was found to have a distinct elemental distribution, with chromium and iron playing crucial roles in enhancing its stability. Based on the interactions of steel corrosion products and passive film at the steel-concrete and steel-solution interface, the possible formation of passive film and the resistance mechanism of CR were proposed. This study substantially augments the comprehension of the corrosion resistance characteristics of CR within SWSSC. Moreover, it proffers invaluable perspectives for the optimization of its utilization, which is conducive to fostering the advancement of reinforced concrete structures in marine and coastal zones.