Bridge Deck Evaluation using Non-destructive Test Methods

The state of Wyoming has 13.1 million sq. ft of road bridges (FHWA 2009), and evaluations have become an important part of the Wyoming Department of Transportation’s (WYDOT) management of bridge repairs. Nondestructive testing (NDE) methods developed in the past 20 years may provide an efficient, standardized, and accurate method for evaluating bridge deck conditions. This report presents the results of an exploratory study performed on three bridge decks in Wyoming: the First Street Bridge in Casper, the Douglas I-25 Bridge, and the Remount Bridge on I-80. The goal is to develop a practical solution that WYDOT can implement. In particular, the solution should capitalize on safety, efficiency and accuracy. The author evaluated each bridge using standard WYDOT practices for chain dragging and half-cell potentials, along with newer technologies of impact echo, thermal imaging, and ground penetrating radar (GPR), which provides a comprehensive assessment of the NDE evaluation techniques. Cores removed from the bridges were compared to the results from the evaluation methods. Damage locations indicated by impact echo, thermal imaging, and GPR generally correlated well and factors are presented in this report. This research suggests that a combination of impact echo with GPR testing provides the most accurate predictions of delamination, debonding, and active corrosion on bridge decks.