Optimization of Acoustic Methods for Condition Assessment of Concrete Structures

Abstract

Extensive experimental studies were carried out to calibrate numerical models related to two acoustic nondestructive testing (NDT) methods: impact-echo (IE) and ultrasonic surface waves (USW). A detailed parametric study was performed to quantify the limitations of the IE and USW methods and to specify the degree of sensitivity of those methods to different parameters, including spatial discretization, overall dimension and material properties of the test object, boundary conditions, and delamination size and depth. Results from this study demonstrate that the effectiveness of the IE and USW methods is limited by their sensitivity to those parameters. This limitation makes the combination of the IE and USW results more effective in detecting and locating the defects within the concrete structures. Finally, the best testing setup, in terms of the spacing between the source and the receivers, was recommended to reliably estimate the slab thickness and to detect and locate the defects.