A reinforced concrete has been used for the civil engineering and construction in the whole world. In order to obtain the real-time information of reinforced concrete, Dawson et al. ¹⁾ attempted to investigate the electrochemical behavior of reinforced concrete by an electrochemical impedance spectroscopy (EIS). John et al. ²⁾ proposed the equivalent circuit to interpret the impedance spectrum of reinforced concrete. Though these methods can be applied to the investigation of conditions of reinforced concrete, an electrical connection of reinforced concrete to the measurement device is required. Keddam et al. ³⁾ proposed the concept of floating electrode for contact-less electrochemical measurement of reinforced concrete. In this method, a four-electrode probe was set on the reinforcement, and the capacitive loop related to the double-layer capacitance at the cement-rebar interface was measured ³⁾.

In the present study, a new method to detect the corrosion site of reinforced concrete was proposed by using two sensing electrodes. The sensing electrodes were placed on the surface of reinforced concrete as working and counter electrodes. The electrochemical impedance measurement was performed in this setup. The impedance related to the corrosion site of steel rebar in concrete with different cover thickness is measured by proposed method. In addition, the current and voltage distributions between sensing electrodes set on the concrete surface were discussed by a finite element method.

Reference:

1. J. L. Dawson, L. M. Callow, K. Hladky and J. A. Richardson, Corrossion/78, No-125 (1978).

2. D. G. John, P. C. Searson, J. L. Dawson, Br Corros J, 16, 102-106 (1981).

3. M. Keddam, X. R. Nòvoa, V. Vivier, Corros. Sci., 51, 1795-1801 (2009).