Nondestructive testing of concrete by ultrasound

Abstract

In this thesis, nondestructive testing of materials using Ultrasonic techniques has been investigated. Especially the determination of the quality of concrete, how the sonic wave `behaves in concrete, relation of acoustic velocity to Elasticity Modulus and to compressive strength, and other problems of testing procedure have been examined. An instrument is built up for this purpose which is designed to measure the transit time of sound propa<ration in a medium between two Ultrasonic Transducers and to display it in microseconds. Thus, the velocity of sound in the medium can easily be derived. If the medium is concrete, then, from the velocity the quality of concrete and other parameters can be determined. The instrument in fact can easily be adapted for transit time measurements of other kinds of materials or media for testing purposes. The instrument basically consists of transmitter and receiver circuits, oounter, control unit and transducers. With the start pulse the circuit starts counting and at the same time the Ultrasonic wave is transmitted. With the stop p^lse vrhich is created after detection of the sonic wave, counting ceases andthe time elapsed occurs on the digital display. The instrument also makes it possible to locate the depths of the flaws inside e.g. cracks, and to determine thickness, if so-nnd velocity in the sample is knovn.