Experimental study on aerial detection of concrete microcracks based on fluorescent selective excitation

Abstract

ABSTRACT In order to solve the problem of detecting and finding microcracks on concrete structures, a method on aerial detection of concrete microcracks based on fluorescence selective excitation was proposed in this study. Concentration brightness relationship curves for fluorescent solutions were plotted based on experimental analysis results. Specialised fluorescent aqueous solutions for concrete microcrack detection were identified as excitation reagents by integrating with the fluorescence development patterns of each solution. Concrete specimens containing authentic microcracks were prepared, and fluorescence selective excitation detection tests for concrete microcracks were conducted. The morphology of microcrack development under fluorescent labelling was scrutinised, and the intervals of opening widths for the examined cracks were quantified. The findings demonstrate that concrete microcracks draw surrounding fluorescent solutions into the cracks through capillary adsorption. Under UV radiation, microcracks manifest dark bands in relation to the fluorescence attachment area due to the loss of fluorescent solution around them. This band elucidates the location and morphology of the marked crack, amplifying its visual representation. Furthermore, the fluorescence selective excitation UV detection method proves effective in identifying concrete microcracks with a width as small as 0.02 mm. The improved UAV equipment was used to carry out the aerial detection experiment on the actual concrete structure.