Optimization of the determination of the ultrasonic pulse velocity in concrete using spectral noise analysis

Abstract

The ultrasonic pulse velocity method is one of the most frequently used non-destructive measurement techniques in construction. One of its indisputable advantages is the speed of measurement and the ability to measure the same place repeatedly. It can therefore be utilised to monitor concrete over time - for example to determine the degree of concrete degradation when exposed to an aggressive environment. However, the ultrasonic pulse velocity method places relatively heavy demands on both the equipment and the qualification of the operator. If the measurements are not conducted accurately, the results may be misleading. This paper therefore deals with the effect of parameter settings of the ultrasonic equipment during measurements. The experiment involved an instrument that includes an oscilloscope and the option to set the gain of the probes and pulse voltage. The evaluation of the measured data was based on spectral analysis of the noise of the measured signal. The output of the paper is then a detailed evaluation of the influence of inappropriate instrument settings on the results and possibilities to optimize the equipment settings based on the outputs of the spectral analysis.