Surface flatness and distortion measurement of precast concrete elements using laser scanning technology

Precast concrete elements are becoming popular for construction of buildings and civil infrastructure. In order to prevent any system failure during the fabrication of precast concrete elements, a great care should be taken throughout the entire manufacturing process to ensure that the hardened concrete surfaces have desired properties in accordance with the design codes. However, the current surface inspection of precast concrete elements primarily relies on manual inspection, which is labor intensive and time consuming. Recently, laser scanning technology has gained popularity due to its technical advantages over other non-contact sensors and several techniques have been developed to perform quality inspection for precast concrete elements using laser scanning data. However, less attention has been paid to surface flatness and distortion measurement of precast concrete elements so far using laser scanning technology. This paper presents techniques that measure surface flatness and distortion of precast concrete elements using laser scanning technology. Using point cloud data obtained from a laser scanner, surface flatness is measured by the FF number in the F-Numbers method, and surface distortion is measured as the deviation of a surface from a plane passing through any three corners of the surface. Experiments on laboratory-scale specimens were conducted to validate the effectiveness of the proposed flatness and distortion measurement techniques.