Bridge Decks Inspection Using Chain Drag and Ground Penetrating Radar

A major contributor of the problems encountered by bridges is the deterioration of the riding surface. It would be very beneficial to locate problem areas under the surface, such as delaminations, before the riding surface spalls out. In this study, we use the conventional chain drag method and compare it with the ground penetrating radar (GPR) in determining subsurface characteristics of concrete decks. The chain drag method was applied on laboratory specimens to determine different frequency characteristics under controlled conditions such as specimens with air filled cracks, with water filled cracks and with steel reinforcement. A GPR system from the West Virginia Department of Transportation (WVDOT) was used to scan three bridge decks. The characteristics of signal patterns from these three different bridge decks were studied to determine concrete bridge deck thickness, and where steel reinforcement and delamination exist. The findings from the GPR analysis were compared with that from the bridge deck inspection reports generated by the WVDOT using the chain drag method.