Impact-Echo Defect Detection in Reinforced Concrete Bridge Decks without Overlays

Abstract

To effectively manage their inventory, transportation authorities are switching to nondestructive testing methods, such as the impact-echo method, to facilitate locating subsurface defects in reinforced concrete bridge decks. In this study, 17 bridge deck specimens with simulated delaminations, voids, deterioration, and poorly constructed concrete were fabricated at different moisture contents to determine what types of defects of varying size and depth can be detected using impact-echo testing. A modified receiver operator characteristic analysis was conducted to assess which types of defects can be discerned from sound concrete. Frequency contour plots for each specimen were used to evaluate how defect characteristics, such as delamination thickness, affect defect detectability. Results indicate that impact echo is generally effective at responding to the presence of delaminations, voids, deterioration, and poorly constructed concrete in bridge decks without overlays. It was found that moisture content does not significantly influence impact-echo readings. This paper also presents other observations regarding how defect thickness, size, and depth affect detectability. The findings of this study support a more effective nondestructive evaluation of in-service concrete bridge decks without overlays using impact-echo testing.