On-site determination of corrosion rate in reinforced concrete structures by use of galvanostatic pulses

Abstract

Galvanostatically induced potential transients can be used to determine the corrosion rate and double layer capacitance (C) of steel in reinforced concrete structures, provided that the steel surface area involved in the measurements is known. An approximate capacitance value, based on previous experience, can also be used to determine polarization resistance even if the area of the working electrode (WE) is unknown, as in the case of measurements on life-size structures using small counter electrodes. In the case of small specimens, in which direct determination of C is possible, the reliability of the pulse technique is comparable to that of other widely accepted electrochemical procedures. In the case of life-size structures, its reliability is lower due to the need to use estimated values of C. The results indicate that neither the magnitude of the perturbing pulse nor the lack of uniformity of the polarization on the WE are factors that significantly prejudice application of the current pulse technique in on-site measurements on large reinforced concrete structures.