Large Aperture Ultrasonic System for Testing Thick Concrete Structures

Abstract

AbstractA large aperture ultrasonic system (LAUS) has been designed and built for testing thick concrete structures. The scalable system consists of 12 ultrasonic units, each hosting 32 individual shear wave transducers with a mechanical dry point contact (DPC) to the concrete surface. The 12 units are attached to the concrete surface using a vacuum case, which holds them in place during operation. Each LAUS unit can be placed individually on the surface to achieve the optimal ultrasonic condition, e.g., to avoid rebars. For the generation of the vacuum, air pressure is supplied to each unit through an air hose. The 12 units define an aperture, which is necessary for fast reconstruction of the subsurface structure. The well-known synthetic aperture focusing technique (SAFT) algorithm has been adopted for this situation, where the individual LAUS units form a linear aperture with not necessarily equidistant spacing between the units. The exact geometrical position of the units, which are individually marke...