Chloride Ion Effect on 316L SS Reinforcement in Fresh and Hardened Concrete: Electrochemical and Microscopic Analysis

The study investigated the effect of chloride ions on corrosion and passivation of 316L stainless steel reinforcement. Initial chlorides were added to simulate fresh concrete contamination, while hardened concrete had a protective layer formed before chloride addition. The evaluation was carried out through electrochemical polarization and impedance spectroscopy techniques, as well as optical and scanning electron microscopy. The results indicated a difference in corrosion current values. The presence of chloride ions during the preparation of fresh concrete promotes the adsorption of Cl^– ions in the form of dendritic growth NaCl and KCl on the stainless steel surface closely associated to micro pits covered by iron and chromium oxide deposits, preventing the adsorption of other species and thereby blocking the formation of the protective film composed mainly of calcium.