OVERVIEW
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.

METHODOLOGY
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.

APPLICATION
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.