Wenner method of impedance measurement for health evaluation of reinforced concrete structures

This paper presents an impedance measurement technique based on the Wenner method, whereby corroded steel reinforcement bars (rebars) in a reinforced concrete surface can be identified. The impedance was measured for specimens containing pre- and post-corrosion rebars. The results of the designed corrosion experiments adhered well to Faraday's laws of electrolysis. At low frequencies, the corroded and healthy specimens showed clear impedance disparities that increased with increasing rebar corrosion, i.e., the impedance decreased as corrosion proceeded. At high frequencies, the impedance merely indicated the rebar depth. The impedance approached a constant small value across the entire frequency range with either sufficient corrosion (over 3 wt%) or an insufficient corroded-rebar depth (10 mm from the surface). An electrical model is also proposed to elaborate these impedance behaviors. (C) 2018 Elsevier Ltd. All rights reserved.