Evaluation of interfacial bond condition between concrete plate-like structure and substrate using the simulated transfer function derived by IE

A method incorporating a simulated transfer function is proposed for effectively evaluating loss of bond between concrete and a substrate for plate-like concrete structures. The simulated transfer function is derived from the impact-echo response in which the Rayleigh wave recorded by the displacement transducer used to generate a realistic force–time function. The results of numerical simulations show that the thickness amplitude corresponding to the concrete overlay decreases with increasing substrate stiffness for the case of a semi-infinite substrate. Some unexpected high thickness amplitudes were found for models with finite substrate thicknesses due to a coupling effect between substrate and concrete layers. The experimental thickness amplitudes for bonded composite plates agree well with the ones predicted from numerical simulations.