Electrochemical study of the corrosion rate of carbon steel in soil: Evolution with time and determination of residual corrosion rates under cathodic protection

Steel coupons were buried in soil boxes for 2.5 months, with or without cathodic protection. A soil from the field was used and moistened by demineralized water or 5 g L-1 Na2SO4 solution. Instantaneous corrosion rates were deduced from voltammetry experiments while average values were obtained by weight loss measurements. A detailed analysis of the polarization curves led to an estimation of residual corrosion rates (tau(rc)) of coupons under cathodic protection. This residual phenomenon could be followed with time and it was observed that tau(rc) decreased down to similar to 10 mu m yr(-1). Cathodic protection could be optimised with this methodology. (C) 2011 Elsevier Ltd. All rights reserved.