Non-destructive strength characterization of concrete using surface waves

The paper presents a description of non-destructive strength characterization of concrete, using ultrasonic probes, and of measuring surface wave velocity. Probes work at frequencies of 40 and 100 kHz, and they are equipped with an exponential waveguide, the end of which has a surface of ca. 1 mm(2). A short characteristic of this type of probe is shown with an analysis of the influence of the inclination angle between the vertical and the examined surface as well as the influence of surface irregularities on ultrasonic wave propagation. The results of laboratory examination are described and examples of application of this measurement method in practice are given. It has been proved that this method has a number of advantages that are very useful in engineering practice. (C) 1999 Elsevier Science Ltd. All rights reserved.