Continuous-wave Laser Thermography for Concrete Crack Evaluation under Moving Conditions

Abstract

This paper presents a continuous-wave laser thermography (CLT) technique for concrete surface crack evaluation under moving conditions. The CLT technique is able to visualize and quantify surface cracks on moving concrete structures by generating a continuous-wave laser source and capturing infrared images at a fixed spatial point. Although the CLT system has spatially limited field of view, it can inspect the entire region of interest (ROI) of the moving target structure. To precisely quantify surface cracks, the data acquired from the entire ROI are integrated and subsequently processed by developing an instantaneous crack evaluation algorithm. In this study, concrete specimens with various macro- and
micro-cracks are specially prepared and used to validate the proposed CLT technique. The test results reveal that various cracks are successfully visualized and quantified within 3% error ratio.