Numerical and Experimental Study of Crack Depth Measurement in Concrete Using Diffuse Ultrasound

摘要

This paper presents a combined numerical and experimental study on the diffuse ultrasonic measurement technique for determining the depth of surface breaking cracks in concrete. A finite element (FE) model for the dis-sipative diffusion in a two-dimensional domain with a surface breaking crack is developed using a commercial FE package; for this purpose, the dissipation term is eliminated by a simple change of variables. Three concrete blocks with a crack depth between 25.4 mm to 101.6 mm are prepared. Diffuse ultrasonic measurements are performed on uncracked and cracked concrete blocks, from which the diffuse energy evolution curves are obtained. The basic material parameters of the hardened concrete, i.e. the diffusivity and dissipation, are retrieved, which are needed for the numerical simulations.