Development and study of ultrasonic pulse velocity measurement system using wave analysis and two-point detection approach

This article focuses on the development and analysis of an Ultrasonic Pulse Velocity (UPV) measurement system used for the evaluation of concrete and Reinforced Cement Concrete (RCC) in civil construction. The UPV tester is essential for on-site assessments of structures, as it is used to measure the velocity of ultrasonic waves within the material, directly correlating with its strength. UPV testing is affected by the attenuation of ultrasonic waves in concrete, particularly due to the interfacial transition zone. Excess ultrasonic attenuation results in the reduction in the received signal amplitude which may also results in the omission of the initial pulses due to threshold comparison at the receiver. The study highlights the impact of receiver gain on threshold error and discusses the limitations associated with ADC sampling rate and amplitude resolution. UPV measurement, including counter or data acquisition approach, have error contributions associated with threshold voltage comparison. The error due to threshold amplitude selection is quantified, emphasizing the importance of accurate signal analysis, particularly in highly attenuating medium. The article presents the design and development of a PC-based UPV tester with automatic threshold error compensation. The system includes a transmitter, receiver, 32-bit microcontroller, and a Graphical User Interface (GUI) for data analysis. The article introduces a two-point linear detection logic to minimize errors caused by selected signal amplitude and omission of initial pulses in transit time measurements. The proposed method provides effective resolution of 10 ns through software, even at low sampling rate of 2 MS/s. The experimental results demonstrate the effectiveness of the developed UPV tester, with comparisons to a reference calibration facility at CSIR-NPL. The standard deviation in the ultrasonic transit time measurement by the developed UPV device, with threshold error correction, was +/- 70 ns.