Abstract
The validity of the ac impedance technique has been tested using polished steel samples cast in concrete cubes, followed by immersion in oxygen-saturated sea water and distilled water. In order to accelerate the corrosion processes the concrete used was very porous with a low cover thickness and comparisons were made with samples of pre-rusted steel specimens.
The impedance results show that, as well as estimating the corrosion rates, information related to the surface film on the steel may also be obtained. The data are in accord with corrosion potential measurements; The results highlight a problem inherent in dc polarisation techniques when applied to the study of corrosion of reinforcing steel in concrete, namely, that steady state data are only obtained many hours after the initial measuring perturbation.
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