Nondestructive measurement of corrosion state of reinforcing steel in concrete

This paper presents a new nondestructive method that uses a multi-electrode electrical resistivity array to measure the complex impedance along the su rface of a concrete structure to determine the position of the reinforcing bars and their corrosion stale. A laboratory demonstration of the new metho d was conducted on a concrete block with four embedded steel reinforcing ro ds, each with a different surface preparation tb simulate a variety of cond itions: corroded, clean, coated bar and gold-plated The gold-plated bar was intended to represent a condition of complete chemical inertness and the p ainted bar was intended to represent the condition that should, in principl e, offer only capacitive coupling to the concrete. The surface spectral res istivity method was able to locate the bars and distinguish between the dif ferent surface impedances of the the bars; therefore, it can be a useful to ol in assessing corroded reinforcement in concrete structures.