Research of Corrosion Monitoring of Rebar in Concrete with Electrochemical Impedance Spectroscopy

Abstract

We developed a probe electrode for impedance measurement to investigate of rebar corrosion in concrete. Impedance measurements of the electrode in an aqueous solution simulating the transition zone of concrete and rebar interface were carried out. The charge transfer resistance R_ct obtained from the two point frequency measurement results by the method developed by Haruyama and Tsuru almost agreed with R_ct estimated by spectral measurement. It was also confirmed that R_ct was drastically decreased by de-passivation following the decrease in pH. Furthermore, impedance measurement of the probe electrode in concrete specimen was carried out.It was confirmed that R_ct was small when the depth of setting the probe electrode was shallow. It was concluded that the state of the rebar/concrete interface can be evaluated by R_ct of the probe electrode installed in the concrete.