Impact of chloride-induced corrosion pits on the mechanical properties of reinforcement bars through 3D scanning and degradation analysis

The ingress of chlorides in reinforced concrete is more detrimental than carbonation, as it forms corrosion pits that act as stress concentration points, compromising the strength and ductility of reinforcement bars. This study examines the degradation of mechanical properties in non-uniformly corroded bars of grades Fe 500D, Fe 550D, and Fe 550 SD, with diameters of 10 mm, 16 mm, 20 mm, and 25 mm, through the impressed current technique. Corrosion loss parameters, including mass loss, critical cross-sectional area, pit depth, pitting factor, and corrosion morphology are obtained through weighing and 3D scanning of rebars before and after corrosion. Monotonic tensile tests are performed to evaluate changes in yield and ultimate strength, as well as ultimate and fracture strain. Degradation equations are developed to analyze the relationship between corrosion loss parameters and mechanical properties of corroded bar, showing that yield and ultimate strengths exhibit the strongest correlation with critical cross-sectional area loss (eta c), whereas ultimate and fracture strains correlate most strongly with maximum pit depth (p). Mass loss (eta m) exhibits the weakest correlation with both strength and strain capacity. By incorporating the pitting factor into the mass loss-based model (k & lowast; eta m), this study presents a novel approach that enhances the correlation coefficient for strength by approximately 15 % and for strain by 49.8 %. These findings underscore the significant impact of pitting corrosion on the mechanical properties of corroded bars.