Inspection and Monitoring of Concrete Structures via Radiography and Weighted Nuclear Norm Minimization Method

Abstract

The location of reinforcement bar in concrete, the bar corrosion, diameter and the depth below the surface are important factors in the evaluation of the load bearing capacity and the usage property within the scope of building condition and damage analysis. Radiographic techniques are used to examine the structure of different buildings. The basic goal of the inspection is the visualization of reinforcement bars, fittings or tension cables. In this research, the Weighted Nuclear Norm Minimization method was used to improve visualization of the hidden structures and defects from the concrete radiographs. The method relies on minimization of the image energy and singular value decomposition for enhancing contrast. The proposed algorithm was successfully applied to radiographic images of concrete segments. Improvement of the structure detail visualization and defect region detection were achieved while preserving structure edge and fine detail imaging information. Evaluation of the image quality enhancement showed that the contrast level to noise increases by a factor of about two in reconstructed images using the proposed method. Also, the background is suppressed towards the zero baselines, and better visual quality is achieved.