Corrosion Characterization of Reinforced Concrete Slabs with Different Devices

There are few works undertaken to verify the accuracy of corrosion measurements. In general, it is assumed that potentiostats are correctly fabricated and then efforts are made to check the repeatability of certain measurement types as polarization curves, with the same or different operator or to calibrate corrosion rate measurements with gravimetry. This paper makes a more in-depth study about repeatability and reproducibility of the measurements and deals with the comparison of corrosion parameters measured in concrete slabs with various degradation types such as carbonation or chloride attack. Different field and laboratory devices were compared. As it is known that the relative humidity is one of the major parameters in the corrosion process and in the electrochemical characterizations, two laboratory conditions (90% relative humidity [RH] or laboratory RH) were tested with a temperature kept constant to 20°C. Also, on-site experiments were made on large concrete slabs extracted from an historical building. The slabs have carbonated and noncarbonated concrete, so active and passive conditions of the steel were measured. They were exposed to outdoor conditions, and differences in the electrochemical parameters due to the temperature and RH changes were also noticed. Results show, in general, good correlation among all the corrosion rate meters.