Microcell versus galvanic corrosion currents in carbonated concrete

This paper presents specific experiments developed to assess galvanic corrosion currents in carbonated concrete. The work investigated the influence of both the steel-concrete interface condition and the cathodic to anodic surface ratio. Galvanic corrosion currents were compared with microcell corrosion currents. In the quasi-saturated condition, galvanic corrosion currents were systematically found to be much higher than microcell corrosion currents. Moreover, the presence of defects at the interface between the anodic steel surface and concrete leads to a significant increase in the macrocell driving potential and, therefore, in the galvanic corrosion current. Furthermore, the galvanic current density strongly increased with increasing cathodic to anodic surface ratio. The coupling of a high cathodic to anodic surface ratio and the presence of steel-concrete interface defects at the anodic surface leads to huge galvanic corrosion current densities.