Characterisation of steel/concrete interface by electrochemical impedance spectroscopy

Abstract

Reinforced mortar specimens were placed in aggressive aqueous solutions and the electrochemical impedance of the reinforcing steel was measured after immersion for 73 weeks. At the end of the test, after removal of the mortar cover, the final condition of the reinforcing steel was examined visually. An equivalent electrical circuit of the interface impedance has been proposed: it includes dispersion terms for taking into account the inhomogeneity of the steel/concrete interface. The validity of the model has been assessed by comparing the results of visual examinations with data obtained by electrochemical impedance measurements which were processed according to the model.