Evaluation of concrete carbonation using time reversal and nonlinear acoustics

International audienceCarbonation of concrete can lead to corrosion of rebar and degradation of structures, including nuclear plant walls and reactors and casks for storage of nuclear waste. Carbonation has been shown to decrease the natural nonlinearity of concrete. Using the time reversal nonlinear elastic diagnostic (TREND) at different frequencies allows for probing at different depths (half a wavelength). By looking at the evolution of the nonlinear response with frequency we can estimate the depth of carbonation. This study will present experimental results aimed at determining the depth of carbonation on medium scale samples (25×50×10 cm and 75×100×20 cm). The samples have been prepared using a protocol known to induce carbonation down to a controlled depth. Several samples are available with carbonation at 0, 1, 2, and 4 cm. We will present the results of the experiments analyzed using several techniques to quantify nonlinearity, namely, pulse inversion and Scaled Subtraction Method (SSM)