Kelvin Probe Electrode for Contactless Potential Measurement on Concrete-Properties and Applications

The practical feasibility of using a Kelvin Probe as a novel reference electrode in the measurement of both potential and polarization pulse response of reinforcing steel in concrete is demonstrated. Potential values measured using a KP reflect greater stability and repeatability than can typically be attained with conventional reference electrodes. Duplicate reinforced concrete beam test specimens with well-differentiated centrally corroding rebar segments were analyzed using both the Kelvin Probe (KP) and a conventional Saturated Calomel Electrode (SCE). Potential profile maps were developed using potential values recorded under static conditions with both the SCE and the KP. Nominal polarization resistance was obtained using potential values recorded under dynamic polarization in both the active and passive regions using the KP and the SCE in conjunction with a customized counter electrode that applied a small galvanostatic polarizing current. In all cases the observed static potential values and dynamic potential response and recovery curves observed using the KP were consistent in shape and magnitude with those observed using conventional reference electrodes