Structural Health Monitoring of Large Structures Using Acoustic Emission-Case Histories

Acoustic emission (AE) techniques have successfully been used for assuring the structural integrity of large rocket motorcases since 1963 [...

Prototype System for Implementing the Ultrasonic Guided Wave Method on the Field

This report presents the latest improvements in a recently developed nondestructive testing (NDT) technique for early detection of various flaws such as corrosion, delamination, and concrete cracking in reinforced concrete (RC) bridge decks. The method, named Ultrasonic Guided Wave Leakage (UGWL) method by the developing authors, involves use of internal steel reinforcement (rebar) as a wave guide for transmitting ultrasonic waves through the system and the measurement of leaked energy at the surface of the concrete. This report builds upon the progress made in the previously published phases of the project (M029 and M066), and aims to further explore the capabilities and practicality of the proposed NDT method. Specifically, efficient coupling of the sensors to the reinforcement and to concrete, durable embedment of sensors in field conditions, detection of corrosion development, benchmarking with half-cell potential (HCP) and chloride level tests, and suggestions for optimal sensor arrays are explored via laboratory and field testing. Results show that with careful placement of sensors and data interpretation, onset and progression of localized corrosion can be detected, which will be useful in developing deterioration models for RC bridge decks in the future. Results show that the UGWL results match well with chloride level tests and HCP testing predictions for potential for corrosion. For field applications, an angled seat made of fast-setting Hydrocal gypsum cement is recommended and it is projected that the optimal angle of attachment is 33 degrees or less from the vertical axis