The Ultrasonic Shear Wave Test Method (UST), commercially known as
A1040 Polygon, is a concrete flaw detection system capable of generating
3-D tomographic images of concrete elements. The basic system consists
of a console with forty transducers configured in ten rows of single
modules containing four Shear wave transducers each. The transducers
are spring-loaded, dry-point contact (DPC) piezoelectric sensors with a
center frequency of 50 kHz. Each transducer is built with a wear-resistant
ceramic tip, which allows testing even on very rough surfaces.
Once the ultrasonic shear wave signal is emitted, the received signals are
processed by the controlling console and then transferred to a laptop
computer via Wi-Fi wireless technology for further analysis by proprietary
software. A synthetic aperture focusing technique (SAFT) data processing
method is then performed to generate the 3-D images of the concrete
element. The reconstructed images are displayed almost instantaneously
on the computer screen as a plan view, cross-section, or isometric view.
Images are generated from the signals received from all the combinations
of PDC transducers (transmitting and receiving) in the antenna array.
The Polygon system is commonly used in concrete, stone, and masonry
structures to detect internal flaws such as delaminations, cracks, and
poorly-consolidated or honeycombed concrete, as well as voids in grouted
tendon ducts systems.