On-Site Determination of the Polarization Resistance in a Reinforced Concrete Beam

Corrosion potential mapping is a useful qualitative technique for measuring the risk of corrosion for reinforcements. However, occasionally this requires not only knowing whether or not the steel is active, but also how fast it is corroding. Polarization resistance is a quantitative technique for measuring corrosion intensity, which has been used only in laboratory experiments on small specimens up to now. In this paper, the basis for application of the polarization technique to a reinforced concrete beam is considered. The distribution of the polarizing potential applied from a small counter electrode and the current flow are mathematically calculated by assuming an approximate model. The polarized region is shown to be confined to a length of the reinforcing bar, which is a function of the true polarization resistance, the concrete resistivity, and geometrical parameters. Various experimental results are presented to demonstrate the reliability of the theoretical predictions for polarization resistance.