Corrosion-Inhibitor Efficiency Control: Comparison by Means of Different Portable Corrosion Rate Meters Available to Purchase

Corrosion-inhibiting substances have been applied to suppress corrosion mainly on bare steel, but when corrosion is progressing, suppression can be achieved if anodic and cathodic reactions are avoided, which is not an easy objective, particularly if the bare metal is surrounded by concrete. In the present article, several corrosion inhibitors are studied to identify their inhibition efficiency in concrete. The percentage of reduction of the corrosion rate without and with inhibitor is named “inhibition efficiency.” This definition calls for the measurement of the corrosion rate and makes its measurement a must when studying corrosion-inhibiting substances. The most extended technique used for the corrosion rate quantification is based on the calculation of the polarization resistance, R_p. For the study presented in this article, several portable corrosion rate meters based on the R_p technique have been used. These equipment are needed for the evaluation of large structures and are able to confine the current in small areas or to determine the steel area affected by the signal for a correct corrosion rate calculation. A comparison among the different corrosion rate meters used for the inhibitor’s efficiency has been done. This comparison has indicated that the corrosion rate meter with nonefficient confinement of the current is not able to detect clearly the passivation state.