This study has assessed and evaluated the performance efficiency of the various types of NDT imaging methods of thermographic, and grayscale imagery, in detecting different types of concrete crack in order to quantifying Near-surface Structural Damage by using image processing techniques, such as optical and thermographic images, and also validation is done for damaged structures obtained through image processing technique with data from visual inspection. With respect to the imagery techniques, the thermographic classifications produced higher accuracies than the greyscale classifications. This is sequel to the fact that, thermographic images contain less variability within the concrete imagery, and equally increases the visibility of cracks that may be otherwise imperceptible, so that results indicates little or no difference between the image processing technique (IR thermography and Optical imaging) and the results obtained by using visual inspection (Feeler gauge and crack detection microscope). Currently, Infrared (IR) thermography has become a common technique for non-destructive inspections in various engineering fields, The IR thermography technique identifies and measures near surface defects by detecting the temperature gradient on the surface of a target object (e.g. a concrete structure).
Thermographic imagery for quantitatifying near surface of the concrete crack damage