On-site measurements of corrosion rate of reinforcements

Abstract

The increasing number of structures suffering corrosion makes the study of their structural safety of importance. The assessment of the residual load-bearing capacity based on the quantification of the actual degree of damage and the prediction of its evolution needs measurement of the steel corrosion rate. Electrical potential and resistivity mapping are the most commonly known techniques, although they are merely qualitative. The measurement of the corrosion rate itself is now feasible. However, the technique is still not extensively used. In this paper, a brief basis of the correct measurement of the corrosion rate is given. The most accurate method is based on the modulated confinement of the current which enables us to limit the steel area polarized by the current. The method is based on the determination of the polarization resistance. In the second part of the paper, the variability of the measured corrosion current due to weather variations is commented on, and values of the time of wetness, as well as of the climatic parameters which influence the moisture content of the concrete, are given in order to obtain the representative value of the corrosion current to be implemented into the structural calculations. The paper ends with a brief description of this implementation.