Novel Method for the Detection of Onset of Delamination in Reinforced Concrete Bridge Decks

This paper presents a discussion and the experimental proof-of-concept results of a novel ultrasonic testing (UT) method to identify the onset of delamination in reinforced concrete bridge decks. The novel UT method aims to provide a system that can be used to monitor and diagnose problems with the steel reinforcement, the steel reinforcement-concrete interface, and the concrete with a single approach. The method utilizes simple-to-interpret energy-based measurements and demonstrates the potential to examine large areas relative to most conventional nondestructive testing methods used for bridge decks. The proposed UT method monitors the leaked energy from a waveguide (steel reinforcing bar) to identify the type, onset, and location of deterioration in reinforced concrete. The proof-of-concept results presented in this paper illustrate the method's ability to identify the onset of delamination (i.e., cracks) with widths less than 0.2 mm (0.008 in.) and its sensitivity to early stage corrosion. This paper also presents the summary of an in-depth review of literature on the status of commercial and research-based ultrasonic testing applications for reinforced concrete.