Chilibon I.

This paper presents results concerning the ultrasound waves’ propagation in concrete. In the field of non-destructive evaluation of concrete, the ultrasonic wave velocity is usually measured and utilized to predict or correlate the strength of concrete, the thickness measure. The pulse-echo method is a technique for flaw detection in concrete based on stress wave propagation. A transient stress pulse is introduced into a test object by a pulse generator transducer on the concrete element surface. Also, by this method one can determine ultrasonic pulse velocity, propagated in concrete specimen and elastic material coefficients. The equipment has a control drive unity (pulse generator, signal amplifier, special soft for data processing), an ultrasonic transmitter transducer and a sensitive receiver piezoceramic transducer. The ultrasonic transmitter transducer is excited by high voltage amplitude electrical pulses, and converts the electrical signal in mechanical vibrations, which propagate into the concrete specimen. The sensor gets the delayed signal for measuring the propagating time between both transducers placed at the end of the tested material specimen. The piezoceramic sensor output signal is dis-played on the memory digital oscilloscope, type TDS 3023, Tektronix, USA. Also, by signal graphic representation analysis in time and frequency one can determine the attenuation coefficient of the pulse in concrete.