Using piezoelectric sensors for ultrasonic pulse velocity measurements in concrete

Abstract

The ultrasonic pulse velocity (UPV) test has been a widely used non-destructive testing method for concrete structures. However, the conventional UPV test has limitations in consistency of results and applicability in hard-to-access regions of structures. The authors explore the feasibility of embedded piezoelectric (PZT) sensors for ultrasonic measurements in concrete structures. Two PZT sensors were embedded in a reinforced concrete specimen. One sensor worked as an actuator driven by an ultrasonic pulse-receiver, and another sensor worked as a receiver. A series of ultrasonic tests were conducted to investigate the performance of the embedded sensors in crack-free concrete and concrete specimens having a surface-breaking crack under various external loadings. Signals measured by the embedded sensors show a broad bandwidth with a centre frequency around 80 kHz, and very good coherence in the frequency range from 30 to 180 kHz. Furthermore, experimental variability in ultrasonic pulse velocity and attenuation is substantially reduced compared to previously reported values from conventional UPV equipment. Findings from this study demonstrate that the embedded sensors have great potential as a low-cost solution for ultrasonic transducers for health monitoring of concrete in structures.

Ultrasonic Monitoring of Crack Propagation of Notched Concretes Using Embedded Piezo-electric Transducers

“…Piezoelectric disc, which has the advantages of low cost, small size, light weight, fast response and etc., is more suitable for being used as a sensing element of embedded piezoelectric transducer (Kee et al 2013;Dumoulin and Deraemaeker 2017a). However, the piezoelectric disc is extremely fragile and vulnerable to be damaged.…”

“…However, the traditional commercially available PZT ultrasonic transducers are usually held in contact with concrete surfaces using coupling agent (gel or grease). Hence there will be inevitable matching problems between concrete and transducers, which are caused by irregular concrete surface or man-made operational mistakes (Xu et al 2012;Kee et al 2013). For in-situ application of the ultrasonic transmission technique, it has limitations in applicability in hard-to-access areas of concrete structures using external probes (Kee et al 2013;Dumoulin et al 2017a).…”

Detection of crack propagation in concrete with embedded ultrasonic sensors

“…This technique demands inspection from the surface and manual handling of the equipment, making a quick evaluation impossible. To avoid the disadvantage of mounting external ultrasound sensors onto a surface, causing coupling problems over time, embedding the sensors into the concrete was proposed [2,3], thus eliminating any changes of the signal due to decoupling. These sensors can be installed in locations that are inaccessible after the structure is built and in service.…”

“…Therefore, beside the method of determining the ultrasonic pulse velocity (USPV) [4][5][6][7], the correlation (C) between time signals from different measurements [2] is used, as well as the change in signal attenuation [8][9][10]. The embedded ultrasonic sensors (EUS) developed for the monitoring of concrete elements are introduced in [11,12].…”

Automated Surface Wave Measurements for Evaluating the Depth of Surface-Breaking Cracks in Concrete

“…Hou et al (2012Hou et al ( , 2013 developed a marble-based smart aggregate for seismic compressive and shear stresses. Recently, Kee and Zhu (2013) developed PZT embedded sensors using a PZT disc that can be used as ultrasonic transmitting and receiving transducers for ultrasonic pulse velocity tests. In this study, the author developed a surfacemount sensor using a PZT disc for generating incident surface waves for surface wave velocity and transmission measurements in concrete structures.…”