Influence of corrosion on reinforced concrete in chloride environments: Top-bar effect, steel fiber reinforcement and cracks

Abstract

Reinforced concrete (RC) is one of the most widely used construction materials due to its strength and durability. However, with time, RC structures may experience deterioration in quality and reduction in service life due to the corrosion of reinforcing steel. This study investigates the influence of corrosion behavior in chloride environments, considering the top-bar effect, the presence of steel fibers in concrete, and the existence of artificial cracks. RC specimens were cyclically exposed to a 35 g/L NaCl solution, while corrosion activity was monitored through galvanic current measurements, mass loss evaluations, and visual inspections of crack map and corrosion distribution. The results indicate that in steel-fiber-reinforced concrete, the initiation of corrosion-induced cracking occurs significantly later than in plain concrete. However, the addition of fibers does not allow to give an anodic control of corrosion. Notably, when the concrete cover is thin, the top-bar effect becomes the dominant factor, introducing micro-defects and weak interfaces at the steel–concrete boundary that facilitate chloride ingress. Consequently, the top-bar effect plays a more critical role than the presence of artificial cracks in controlling the initiation and propagation of corrosion. The results show that corrosion-induced cracks in steel fiber-reinforced concrete develop more slowly than in conventional concrete. The addition of fibers does not allow to give an anodic control of corrosion. Top-bar effect is more important than artificial crack in case of weak cover thickness.