Nondestructive evaluation of epoxy-coated reinforcing bars in concrete using bi-electrode half-cell potential techniques

This study evaluated two half-cell mapping methods for nondestructive evaluation of epoxy-coated rebar (ECR) in concrete: the semi-fixed bi-electrode and the moving bi-electrode methods. These methods were expected to provide early detection of corrosion-related damage and ensure adequate time for repair. The techniques were evaluated by comparing the half-cell measurements using the two half-cell mapping techniques and measurements using the standard half-cell technique. The study found that in concrete specimens the response of both bi-electrode techniques was similar to that of the standard half-cell technique. Each technique was sensitive enough to distinguish between ponded and unponded regions along the Type I test beams. Although additional research is required to determine exactly how sensitive either bi-electrode technique is for assessing corrosion of ECR in concrete, it is clear that the use of any nondestructive tool for condition surveys of bridge decks would benefit VDOT and Virginia. The author recommends that the Type I test beams used in this study continue to be ponded until corrosion is initiated to aid in understanding the benefit of using the two bi-electrode methods during the various stages of corrosion. In addition, the Virginia Department of Transportation's Structure & Bridge Division should identify two structures that are beginning to show signs of corrosion, one bridge with ECR and the other with bare bar, to be used in a field study to determine if either bi-electrode method would benefit VDOT as a condition survey tool.