Approach to consider self‐corrosion in corrosion monitoring of reinforced concrete structures exposed to chlorides

Corrosion processes of steel in concrete contaminated with chlorides take place as macrocell corrosion as well as self‐corrosion (i.e., microcell corrosion). While macrocell corrosion can be detected by element current measurement, self‐corrosion cannot be precisely determined electrochemically. This results in deviations in corrosion investigations between the mass losses calculated coulometrically from macrocell current measurements and the actual, corrosion‐related gravimetric mass losses. This is relevant in practice as part of corrosion monitoring. In the following, a simple approach is presented by considering this self‐corrosion current mathematically in the macrocell current measurement. The empirical regression functions determined for this purpose can be applied to a large number of different influencing parameters and allow the determination of the cumulative steel degradation at time‐varying macrocell current densities under consideration of different safety levels. This allows a much more accurate estimation of the actual corrosion‐induced mass losses during corrosion monitoring than previously possible. Self‐corrosion results in deviations between the electrochemically calculated mass losses of the reinforcement from the macrocell current measurement and the actual gravimetric mass losses during corrosion monitoring in chloride‐contaminated reinforced concrete structures. Empirical regression functions are presented that can be used to take self‐corrosion into account with various confidence levels.