An Improved Method for Estimating Polarization Resistance from Small-Amplitude Potentiodynamic Scans in Concrete Available to Purchase

Many corroding interfaces exhibit electrochemical impedance response similar to that of a polarization resistance (R_p) associated with the corrosion process, in parallel with a constant phase angle element (CPE) having relatively large admittance. Such conditions are encountered often in the case of steel in concrete. While polarization measurements using a forward and reverse potential scan rate (dV/dt) can be helpful to subtract the contribution of an ideal interfacial capacitance (C) by using a C dV/dt correction, in concrete the pronounced frequency dispersion of the CPE complicates the time-domain response, and correction is not straightforward. A solution to this problem was presented and applied to evaluate the CPE parameters and estimate R_p of steel in concrete from cyclic-scan polarization measurements. The technique was demonstrated for experiments with plain steel and galvanized rebar in concrete.