Impedance spectroscopy in reinforced concrete: Procedure for monitoring steel corrosion Part I Development of the experimental device

An original experimental protocol is devised to monitor the corrosion of a reinforcing steel embedded in a cement-based material by impedance spectroscopy. The principle of this method is based on the use of a sinusoidal potential applied to measure the impedance response. Preliminary tests were performed from a three-point configuration measurement using classical reference electrodes. Results highlighted the limitations of the introduction of such a reference electrode at high frequencies. Simulations from electric circuits suggested an explanation for these high frequency artifacts. They are mainly due to the high impedance value of the reference electrode which leads to the generation of some artifacts in the impedance response of the studied system. Finally a convenient solution is proposed to eliminate these perturbations and so obtain a suitable measurement of the impedance response of the reinforcing steel/cement based material system at high frequencies.