Nonlinear ultrasonic testing by Rayleigh waves on control of concrete cover – Application in thermal damage evaluation

International audienceThis paper present the use of Rayleigh wave in Dynamic Acousto-Elasticity Testing for non-destructive evaluation of concrete cover. Dynamic anomalous nonlinear elastic behavior with primary manifestations like modulus decrease reached to conditioning state and slow dynamic process, has been observed in many variety of solids, also in concrete. In ideal, we hope the surface wave with its advantages for an on-site measurement, can show locally nonlinear properties of a cover concrete layer with depth predetermined. In the first step, we work in laboratory with a small size specimen series of concrete damaged thermally in different temperature. In this paper, only conditioning level is analyzed to be sensitive with thermally damage by Rayleigh waves. The variation trend is compared with NRUS method result on the first bending mode. This technique offers a real possibility of test by a single face of a structure which opens up possibilities for transposition on site