Effect of the stirrup on the transport of chloride ions during electrochemical chloride removal in concrete structures

Abstract Chloride ion is one of the most important factors leading to the corrosion of steel bar embedded in marine concrete structures. The chloride induced corrosion is also considered harmful to the service life and durability of structures. Electrochemical chloride removal (ECR) is a nondestructive method, which can be used to terminate the corrosion and prolong the service life of concrete structures to minimize the economic and environmental costs caused by structural reconstruction. The presence of stirrup embedded in concrete affects the potential distribution in the concrete structure, and further affect the transport of chloride ions during the ECR treatment. In this study, a theoretical model of a concrete structure containing stirrups was established to investigate the effect of the stirrups on the transport of chloride ions during ECR. Based on both modelling and experimental results, the stirrup has two-fold effects on the transport of chloride ions in the local region close to the concrete section with the stirrup. On one hand, the shielding effect makes the region enclosed by the stirrup become an equipotential body, and hinders the migration of the chloride ions; on the other hand, the accelerating effect caused by the increasing cathodic area due to the existence of stirrup, increases chloride ion migration speed.