Ultrasonic pitch and catch technique for non-destructive testing of reinforced concrete slabs

Abstract

This study aims at evaluating reinforced concrete (RC) bridge elements using ultrasonic pitch and catch (UPC) non-destructive testing (NDT) technique. A validation reinforced concrete slab with two embedded layers of rebars and artificial defects (voids, honeycombs, and debondings) was designed and tested. A commercial UPC NDT device (hereafter called “UPC device”), which is based on the ultrasonic shear-wave test method using dry-point-contact transmitting and receiving transducers in a “pitch-catch” configuration, was used to map internal defects of the validation RC slab. The recorded data from the UPC device was analyzed using a modified synthetic aperture focusing technique (SAFT). A software was developed to reconstruct 2-D images of the RC slab cross-sections using novel signal filtering and processing techniques. The results revealed that the 2-D image reconstructed from the developed software accurately exhibited locations and horizontal dimensions of the steel rebars, voids, and debondings. In addition, the developed software was capable to provide much higher resolution and sharper images of the anomalies inside the RC slab compared to the UPC device’s proprietary imaging software.

Ultrasonic Pulse-Echo Signals for Quantitative Assessment of Reinforced Concrete Anomalies

“…The low density of foam allows for the ultrasonic waves to be reflected in a similar manner to the presence of air. In this research, the testing slabs (The Ultrasound Tomographer called MIRA, manufactured by Germann Instruments (Evanston, IL, USA) was used to conduct the tests) as shown in Figure 2a, which is same as the one in [35]. A specimen of reinforced concrete (RC) slab was designed with two layers of #5 steel rebars with a spacing of 203 mm and artificial defects.…”

“…The standard SAFT's results can be further improved by introducing a few developments, such as calibrating the sagging in the resulting images due to the long wavelength of the pulse [33,34], the extended SAFT methods and applications [35][36][37][38][39][40][41][42], the AI-based algorithms applications [43,44], and ultrasonic image by using both linear and non-linear wave properties [45].…”

Ultrasonic Pulse Echo Signals for Detection and Advanced Assessment of Reinforced Concrete Anomalies

“…Various signal processing techniques enhance the detection capabilities of ultrasonic NDT applications, where signals are often mixed with noise. The ultrasonic signals should be denoised, which is feasible using short-time Fourier transform, wavelet transform, improved wavelet transforms, adaptive filtering, and empirical mode decomposition (EMD) [20][21][22][23][24][25][26]. Each technique has its strengths and weaknesses, which are considered when selecting the appropriate method for the given application.…”

Detecting Reinforced Concrete Rebars Using Ground Penetrating Radars

“…In addition, the GPR method has also been widely used for concrete moisture evaluation [13], deterioration mapping of old bridge decks [14], tracking cracks [15], assessment of rebar corrosion in concrete slabs [16,17], detection of embedded defects [18], detection voids in grouted post-tensioned 2 concrete ducts [19], investigation of concrete mix variations and environmental conditions on defect detection [20], identification of corrosion-induced anomalies of bridge decks [21], rebar detection [22], visualization defects of fiber-reinforced polymer-wrapped reinforced concrete slabs [23][24][25], and mapping rebar layers [26].…”

“…Zatar et al [27] proposed a method based on a synthetic aperture focusing technique to determine the rebar depth and spacing. Chang et al [28] introduced a physical model that accounts for the electromagnetic signature of a buried reinforcing steel bar, considering the rebar's radius.…”