Limitations of the linear polarization method to determine stainless steel corrosion rate in concrete environment

The linear polarization is a non-destructive way of estimating the instantaneous corrosion rate of a metal. In case of reinforced concrete, the method is restricted mainly because of a concrete resistance, unknown area of the polarized reinforcement and non-uniform corrosion. In spite of that, thanks to the polarization resistance it is possible to estimate whether the reinforcement corrodes in activity or passivity. The results imply that sometimes even the knowledge of Rp is insufficient for stating activity or passivity of the material. It has been proved, however, that the shape of the curve determining Rp by linear polarization may frequently indicate the corrosion behaviour. It is possible to evaluate the deviation of the point of zero current from the free corrosion potential which was measured prior to the linear polarization and also to evaluate the deviation of the polarization curve from the regression line, which is defined by the coefficient of determination.