Numerical study of the linear polarisation resistance technique applied to reinforced concrete for corrosion assessment

The linear polarisation resistance (LPR) technique is increasingly being implemented to assess the corrosion rate of steel reinforcements in concrete. However, a lack of reliability is often observed experimentally. In order to improve the physical comprehension of the LPR technique, FEM simulations were performed. Several measurement devices using annular and rectangular probe geometries were simulated and the numerical experimentation allowed the relevance of RILEM recommendations for on-site measurements to be tested. It was shown that the LPR measurement using annular counter-electrodes with confining devices was a real three-dimensional physical problem and the non-uniform distribution of the polarising current on the steel surface is actually a major source of error since it is not taken into account by the usual protocols. Moreover, it was found that some complexity was induced by the use of guard-rings.