Sensitivity of Two Stress Wave-Based Methods for Nondestructive Evaluation of Concrete Slabs

AbstractAmong several nondestructive testing methods, impact echo (IE) and ultrasonic surface waves (USW) have shown promising results for performance monitoring and condition assessment of concrete structures. To ensure their proper use, it is critical to quantify the potentials and limitations of those methods and to specify the degree of sensitivity of each method to different structural and defect parameters. In this study, the sensitivity of the IE and USW methods are investigated through high spatial resolution and extensive numerical simulations of intact and defective slabs. The results of the experimental and numerical studies show that the effectiveness and reliability of these two methods are limited by their sensitivity to several parameters, including boundary conditions, the geometry and material properties of a concrete structure, and the size and location of discontinuities in structures. Given the sensitivity of each method to several parameters, the combination of the IE and USW tests is recommended for more reliable quality control of newly constructed concrete structures and condition assessment of existing ones.