SEDL / STP / STP1065-EB / STP25019S

Study of the Corrosion of Concrete Reinforcement by Electrochemical Impedance Measurement

Lemoine, L
Infremer, Plouzané,

Wenger, F
Ecole Centrale Paris, Paris,

Galland, J
Ecole Centrale Paris, Paris,

Pages: 16    Published: Jan 1990

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Abstract

Electrochemical impedance measurement is a convenient method to analyze the corrosion phenomena of steel in concrete. A data analysis method is used on the basis of an equivalent circuit correlated to the properties of concrete and electrochemical mechanisms. The different parts of the diagram versus frequency allow characterization of the concrete cover, the presence of a film at the surface of steel, the transfer resistance connected to the anodic reaction, and some other relaxation phenomena. Some agreement has been obtained with mass losses.

A mathematical model has been developed in order to analyze the results on large concrete beams with a small-size auxiliary electrode. Particular emphasis is given to the spatial location of an active area in order to demonstrate the feasibility of such a method either on large specimens or on real structures. For this application, the principle of an alternative method was developed. An auxiliary electrode is used with an electrical guard. At low frequencies (<10 Hz), the first experimentation gives encouraging results.