Evaluating Concrete Damage in Bridge Decks with and without Overlays Using Nondestructive Testing Procedures

The state of Wyoming alone has 13.1 million square feet of bridge deck, and evaluation of those decks has become an important part of the Wyoming Department of Transportation's (WYDOT) management of bridge repairs. The authors believe that development and advancement of nondestructive evaluation methods over the past 25 years may provide a more efficient, standardized, and accurate method for evaluating bridge deck conditions compared with current practices. A study was performed on three bridge decks in Wyoming: the First Street Bridge in Casper, the Douglas I-25 Bridge, and the Remount I-80 Bridge. For each bridge, an investigation was done using standard WYDOT practices for chain dragging. In addition, the bridges were evaluated using impact echo, thermal imaging, and ground-penetrating radar (GPR) techniques. All three methods considered were successful, and the damage locations between the impact echo, thermal imaging, and GPR generally correlated well. Based on this study, a complete bridge deck evaluation should combine impact echo with GPR testing to provide the most accurate predictions of delamination and debonding in support of optimal maintenance decisions.