Estimation of residual corrosion rates of steel under cathodic protection in soils via voltammetry

• Published in: Corrosion science Vol. 73; pp. 222 - 229
• Main Authors: Barbalat, M., Caron, D., Lanarde, L., Meyer, M., Fontaine, S., Castillon, F., Vittonato, J., Refait, Ph
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-08-2013; Elsevier
• Subjects: A. Steel; Applied sciences; B. Cyclic voltammetry; B. Polarization; B. Weight loss; C. Cathodic protection; Cathodic protection; Corrosion; Corrosion environments; Corrosion prevention; Corrosion rate; Current density; Exact sciences and technology; Metals. Metallurgy; Soils; Steels; Voltammetry; Weight loss measurement; C. Cathodic protection; B. Cyclic voltammetry; A. Steel; B. Weight loss; B. Polarization; Cathodic protection; Cyclic voltammetry; Corrosion; Mass loss; Corrosion rate; Steel; Corrosion protection
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2013.03.038

•Residual corrosion of steel under cathodic protection is studied in aerated soils.•Residual corrosion rates under cathodic protection are estimated via voltammetry.•Cathodic reaction is modelled with a mixed activation–diffusion controlled kinetic.•The methodology presented here could diagnose a deficient cathodic protection.
Steel coupons were buried in soil for 2months under cathodic protection. Their residual corrosion rates were deduced from voltammetry and weight loss measurements. In aerated soils, the current density due to O2 reduction, jK,O2, was modelled with a mixed activation–diffusion controlled kinetic. The anodic part jA of the current density j, computed as jA=j−jK,O2, obeyed Tafel law. Its extrapolation to the protection potential gave a corrosion rate (∼7μmyr−1) consistent with that obtained from weight loss measurements. With a deficient protection, corrosion rates remained at ∼80μmyr−1, a value given by both methods.