Investigation of Ground-Penetrating Radar, Impact Echo, and Infrared Thermography Methods to Detect Defects in Concrete Bridge Decks

Abstract

A reinforced concrete bridge deck is often at risk of many forms of deterioration which affect its service life and maintenance cost. Nondestructive test (NDT) methods have seen increasing use by departments of transportation to locate deterioration in bridge decks before their condition rating becomes critically low and to help plan bridge deck preservation activities. Nonetheless, uncertainty in what forms of bridge deck deterioration each NDT method can identify has posed challenges in best deploying NDT methods for deck condition assessments. Thus, in this study, a full-scale 18 ft by 31 ft reinforced concrete bridge was constructed with defects in the deck simulating reinforcing steel corrosion, delaminations, concrete deterioration, voids, and poorly constructed concrete. The deck was evaluated with ground-penetrating radar, infrared thermography, and impact-echo nondestructive technologies to evaluate their potential for defect detection. Receiver operator characteristic analysis was implemented to quantify the capability of a given NDT method to detect a particular defect. Conclusions concerning which forms of concrete bridge deck deterioration each NDT method can detect were developed. It was found that of the three NDT methods considered, impact-echo testing was the most effective to evaluate the condition of bridge decks. Impact echo was able to detect both shallow and deep delaminations as thin as 0.01 in., shallow corrosion-induced delaminations, concrete deterioration, and some of the shallow voids; however, it was unable to detect deep voids, poorly constructed concrete, and mildly deteriorated concrete.