Identification of sewer pipes in concrete structures through ultrasonic tomography

Abstract

Non-destructive evaluation of concrete structures has been increasingly used, whether for checking the deterioration of the element over time or for identifying faults during concreting. Special attention has been given to the identification of water and sewer pipes integrated into the structural elements since their presence can interfere in their performance. Thus, the aim of this paper is to evaluate the use of ultrasonic tomography to identify the presence of PVC sewage pipes in concrete structures. The tomographic reconstruction algorithm was implemented in MatLab. To verify the effectiveness of the method, a concrete specimen of 20cm x 20cm x 20cm with an internal 10cm PVC sewer pipe was developed. In order to study mesh dependency, meshes of 5cm x 5cm and 2.5cm x 2.5cm were used. To display the tomograms, contours were used.  It was possible to locate and get information regarding the geometry of the pipe.  Mesh dependence has a significant influence on the geometric representation of the internal defect. Smaller meshes lead to better tomograms. Ultrasonic tomography in concrete has great potential to be used to identify non-homogeneities in concrete structures.