Nebraska Department of Roads
Acoustic emission, Bridge decks, Delamination, Ground penetrating radar, Nondestructive tests, Reinforced concrete, Reinforcing bars, Structural health monitoring
Many different techniques of health monitoring and nondestructive testing (NDT) methodologies have been employed to detect rebar and overlay delamination in reinforced concrete bridge decks. NDT to monitor delamination in concrete bridge decks was initially done by acoustic sounding techniques such as chain dragging and hammer sounding. These relatively simple methods can only be employed by trained and experienced inspectors, require a lot of time, and yet provide only a qualitative assessment of the condition of the specimen. Recently, due to advancements in imaging technologies, acoustics, seismic measurements, and electromagnetics; NDT methods such as Ground Penetration Radar (GPR), Ultrasonic testing, and Impact Echo have gained popularity. Other NDT techniques also utilized to monitor concrete bridge deck delaminations include: radiography, infrared thermography, and acoustic emission, each with its own benefits and drawbacks. Radiography is expensive and requires radioactive protection, thus only highly trained and licensed personnel can carry out these methods, and it still poses potential safety hazards. Applications of infrared thermography are limited due to their heat differential requirements, which also creates application time constraints. Acoustic emission method requires load control, which limits it to be used primarily in lab research (Ghorbanpoor et.al. 2003). The proposed methodology is intended to provide a continuous health monitoring method for reinforced concrete bridge decks. The ultimate goal of the project is to develop a novel method using ultrasonic wave propagation (UWP) to identify the onset of rebar delaminations and to provide continuous health monitoring for the structure.