Detection of Delaminated and Cracked Concrete with Unmanned Aerial Vehicles

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The unmanned aerial vehicles or drones provide eyes that reach the sites and parts of structures that are difficult to access. They are very valuable when high bridges with large spans, which would typically require special vehicles, hoists or personnel with climbing skills, are inspected. If a drone carries infrared sensors and high definition lenses with a long focal length, its scope can be extended to non-destructive damage detection. This article presents the results of a study on the use of drones for such a purpose. The investigations were first performed under controlled laboratory conditions and then on-site on a benchmark bridge. Two performance indicators for the optimal definition of damages of concrete bridges were studied: extension and location of delaminated areas, and the position and width of the cracks. The results demonstrate substantial added value compared to existing visual inspections, mainly in the form of consistent information that does not depend on the knowledge and skills of the inspector.