Metal Corrosion Rate Determination of Different Solutions and Reinforced Concrete Specimens by Means of a Noncontacting Corrosion Method

All the current techniques used to measure the metallic corrosion require contact with the metal. Particularly, in the case of reinforcement corrosion, this signifies the need to reach the bar that is embedded in the concrete, which consequently may result in the disruption of the integrity of the real structures. This paper studies the limits of application of a new method for polarizing the reinforcement or any metal in an electrolyte, without the need of direct contact. The polarization is obtained through the induction of current from an external electrical field. The current runs through the electrolyte and the metal in parallel, depending on the electrode arrangement. The resulting polarization resistance calculated is termed as inductive, R_p = R_pi, as reported in a previous paper. The inductive R_p is calculated by the model of resistances in parallel, which requires a separate measurement of the electrolyte ohmic resistance. In this study, solutions with several resistivities and concrete specimens with and without chlorides have been tested. Results indicate that electrolytes of low resistivity mask the measurement, and consequently, R_pi could not be calculated. In electrolytes with high resistivity, such as concrete, the feasibility is found to depend on the relative values of R_e and R_pi.