Prediction of mechanical properties of thick concrete members or masonries utilizing ultrasonics

Abstract

The ultrasonic method is an effective “tool” for in-situ determination of the compressive strength of materials. However in cases of very thick concrete elements or historical masonries, the high attenuation of the transmitted pulse makes it practically impossible to detect the acoustic signal on the other side of the wall. Alternate setups, such as placing the transducers in corners reduce the reliability of the method. In order to optimize the sensitivity of the method, the use of properly placed triangular prisms is proposed in the present work. The transducers are placed on the proper side of the prism, thus changing their orientation and the direction of the emitted ultrasonic wave with respect to the wall surface. Initial results focusing on concrete structural members are presented herein. Experimental measurements were conducted in order to accurately calculate the “travel times” for each segment. Finally, wave scattering was theoretically considered using properly defined slowness curves for the wall materials. The obtained results are promising and provide the basis for the extension of the technique on problems of brick or stone masonry.