Calibration by gravimetric losses of electrochemical corrosion rate measurement using modulated confinement of the current

Abstract

The measurement of on site corrosion rate is a technique that has been extended for the increasing necessity to determine the service life of concrete structures. The most reliable method is the Polarization Resistance determination by means of the modulated confinement of the current. In the present paper, a calibration of corrosion rate measurements with the modulated confinement of the current method (MCC) is given, comparing the electrochemical results with the gravimetric losses of the rebars. This gravimetric comparison is the reference for the correct calibration of the corrosion rate measurement, following the RILEM Recommendation of TC 154-EMC. Some concrete slabs with different chloride contents were made. In some cases, a hole was drilled over some steels for an additional chloride introduction during the test in order to develop very localized attack. The comparison of electrochemical and gravimetric metal losses confirms the reliability of the modulated confinement of the current method, except when the concrete is very young due to the very low resistivity. Confinement is then not always reliable when the concrete is very wet, and the attenuation of potential method has to be used instead.