Evaluation of embeddable potential sensor for corrosion monitoring in concrete structures

Embeddable potential sensor based on MnO2 was assembled and characterised in concrete. The stability, reversibility, polarisability and impedance characteristics have been studied with respect to known reference. The corrosion performance of reinforced steel with respect to MnO2 sensor was monitored by different electrochemical techniques. Reversibility of MnO2 sensor indicated that difference of ±5 mV between the forward and reverse scan indicates the better reversibility characteristics in concrete. The rebar potentials (ER) of steel with respect to MnO2 are −315 and −525 mV for passive and active conditions of rebar in concrete. The corrosion current from potentiodynamic polarisation and Rct from a.c. impedance technique clearly differentiated the behaviour of steel embedded in chloride contaminated concrete (active condition) from uncontaminated concrete (passive condition) with respect to MnO2 sensor. All these studies revealed that corrosion monitoring of steel in concrete using embedded MnO2 as a better potential sensor for steel in concrete. In addition it is easy to fabricate for amenable miniaturisation, varied configuration as demanded for corrosion monitoring in concrete structures.