Electrochemical Impedance Spectroscopy to Study the Carbonation Behavior of Concrete Treated with Corrosion Inhibitors

In this paper, electrochemical impedance spectroscopy was used as non destructive technique (NDT) for studying the carbonation behavior of the concrete sample treated with migratory type of organic corrosion inhibitors. Concrete carbonation was achieved in carbonation chamber by maintaining 5% CO2 by volume, 60-70% relative humidity and 30 +/- 2 degrees C temperature for 90 days. The experimental results show that with progressive carbonation, porosity of the concrete reduces and results in denser microstructure. The concrete surface treated with corrosion inhibitor C.I. 1 (amine - ether based) and C.I. 2 (2-aminobenzoic acid) shows the behaviour different form the control sample at the end of exposure conditions. Impedance results indicate that carbonation depth can be predicted by analyzing the high frequency arc of Nyquist plot. Also, both of the tested inhibitors were able to form a passive layer around the rebar surface and their efficiencies improved with time.