Electrochemical methods for on-site corrosion detection

The corrosion mechanism is of electrochemical nature and then, electrochemical techniques are the most adequate to measure the process and quantify it. In present paper are briefly described the most applied on site: corrosion potential, resistivity, galvanic current, and polarization resistance. In general, due to the difficulty to measure quasi-infinite in size reinforcement, the measurements are made on probes embedded in the cover attached to the bars. From the techniques used, only linear polarization is quantitative. Corrosion potential provides information about the corrosion risk, and resistivity is directly related with the concrete water content. The galvanic current is misleading if real size of anode and cathode are unknown. Although, frequently mistaken, galvanic current is not equal to corrosion rate and reference to areas involved is needed. Two examples are described on the monitoring of these methods.