Probing Macro Cracks in Concrete Using Diffuse Ultrasound (oral Only)

International audienceSeveral difficulties are encountered in the use of acoustic techniques for the characterization of concrete in an industrial context. ISO and ASTM standards state that ultrasound frequencies in the range between 20 kHz and 150 kHz should be used. When the frequency is increased (up to about 600kHz), ultrasound measurements become more complex, in particular due to multiple scattering, resulting from the presence of aggregates similar in size and spacing to the ultrasound wavelength. However, one can show that the complex propagation of multiple scattered waves in concrete can be simplified into a standard diffusion law. The fit of the coda waves energy envelope with the solution of this equation, allows to estimate the diffusion parameters: the diffusivity, the dissipation and the arrival time of the maximum energy.The present study reports recent experimental/simulation results allowing to probe localized surface breaking cracks in concrete