In this work an instrumentation that combines ultrasonic tomography with accurate motion control is presented. The acquisition of high-response tomographic images is achieved using transducers in a linear array through the efficient control of their phase characteristics both in transmit and receive modes. Moreover, an accurate mechanical adaptation is designed in order to move the ultrasonic probe with a constant velocity and a sequence of tomographic images is recorded. Then, the 3D endoscopic characteristics of the measured object are extracted via the reconstruction of the 3D volume.
The acoustic waves are able to penetrate the thick mortar and provide high fidelity information of the underneath internal cracks. Specifically, the mortar is appearing as the high intensity upper layer due to its scattering, while the thickness seems decreased due to the high acoustic velocity. On the other hand, internal cracks are appearing as separated elements of varying intensity. It is observable that the internal cracks shape is reconstructed successfully, while the detailed pattern of the concrete sample is also evaluated.
This work was conducted in collaboration with the Laboratory of Building Materials, School of Civil Engineering, AUTH. Concrete and mortar samples have been analyzed in order to measure the reinforcement or the coating thickness.
Concrete Tomography indicative images: