Evaluation of eddy current and magnetic techniques for inspecting rebars in bridge barrier rails

This paper reports on a feasibility study of using eddy current (EC) and magnetic flux leakage (MFL) methods to detect corrosion damage in rebars that anchor concrete barrier rails to the road deck of bridge structures. EC and MFL measurements were carried out on standalone rebars with and without artificial defects of 25% and 50% material loss, using a commercial EC-based rebar locator and a MFL system that was developed using giant magnetoresistance sensors to detect leakage fluxes from the defects. Both techniques can readily detect the defects at a distance of 2.5” (63.5 mm). The amplitudes of the EC and MFL signals vary monotonically with the amount of material loss, indicating the potential of using the techniques to quantify material loss of standalone rebars.