Effects of Moisture Availability on Corrosion Kinetics of Steel Embedded in Concrete

The quantitative relations between the corrosion rate (in terms of the corrosion current density, Icorr) of steel in concrete and the electrolyte supply was studied. The degree of pore saturation of concrete determined the type of natural control of the corrosion kinetics of the embedded steel. Corrosion of steel in atmosphere and in concrete in an active state conformed to a semi-logarithmic relationship between Icorr and the relative humidity (RH) of the atmosphere or the degree of pore saturation of the concrete. The latter variable dictated resistivity of the concrete. However, once corrosion at a steel-concrete interface started, it was found that the concrete cover could be detrimental to the corrosion process of the embedded steel. The porous nature of the concrete resulted in longer wetting times than bare steel surfaces.