Relation between resistivity of concrete and corrosion rate of reinforcing bars caused by galvanic cells in the presence of chloride

Abstract

The article presents the experimental study and theoretical analysis of the relationship between the resistivity of the concrete (ρ) and the reinforcement corrosion rate. The corrosion process was simulated using a galvanic sensor. The distance between the galvanic sensor plates and the sizes of the plates are selected in such a way as to simulate the functioning of microcells in the case of corrosion in the presence of chlorides. Tests carried out on bimetallic galvanic sensor embedded in mortar have corroborated a direct proportionality between the rate of corrosion and resistivity of concrete. The role of ohmic resistance in the corrosion process have been estimated by comparing model calculations and experimental results. The hypothesis of ohmic control the corrosion process in case of microcells was rule out. It was suggested that the process of corrosion is governed by the fraction of metallic surface wetted by porous liquid. A form of the equation for the current in a galvanic cell is proposed, taking into account the above model representations. The proposed approach can be used to simulate the corrosion process of reinforcement in concrete and to assess the effect of the saturation of concrete with moisture on the corrosion rate.