A comparison of nondestructive evaluation methods for bridge deck assessment: Fid-Bau Portal

A comparison of nondestructive evaluation methods for bridge deck assessment

Scott, M. / Rezaizadeh, A. / Delahaza, A. / Moore, M. / Graybeal, B. / Washer, G.

Nondestructive evaluation techniques that have been developed for the purpose of inspecting bridge decks were tested on the Van Buren Road Bridge for a comparison study. Techniques that were the focus of the study were primarily directed at detecting corrosion-induced delaminations below the surface of the concrete. These techniques included the chain-drag method, impact-echo, and two types of ground penetrating radar. Ground truth data based on a careful implementation of the standard chain drag method were confirmed by examining concrete cores that were extracted from the deck. The impact-echo and ground penetrating radar methods were both compared to this original reference data. Although the chain-drag method was used as a reference, it was also investigated to assess its reliability. The results showed that current technology implementing acoustic techniques, such as the chain-drag method and impact-echo, are generally consistent with results from coring when they are properly carried out. However, there are significant drawbacks to the two acoustic methods implemented in this study. The chain drag method is susceptible to inconsistencies and errors due to subjective interpretations an inspector must make to carry out this method. The quantitative impact-echo method reduces the chances of subjective errors but it is extremely time consuming to carry out. The drawbacks of these acoustic methods, which include the inability to investigate asphalt-overlaid decks, motivate the investigation of the radar methods that were also included in this study. The two ground penetrating radar systems that were included in this study were investigated because they represent a potentially faster and easier way of conducting bridge deck investigations. This technology may also mature to allow delaminations to be detected through asphalt overlays. Although the technology is continuing to be improved, the current state of the art commercial systems and even the prototype system used in this study do not produce consistent responses to delamination features in bridge decks.