Monitoring of the Production Process of Graded Concrete Component Using Terrestrial Laser Scanning

Abstract

Accepting the ecological necessity of a drastic reduction of resource consumption and greenhouse gas emissions in the building industry, the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart is developing graded concrete components with integrated concrete hollow spheres. These components weigh a fraction of usual conventional components while exhibiting the same performance. Throughout the production process of a component, the positions of the hollow spheres and the level of the fresh concrete have to be monitored with high accuracy and in close to real-time, so that the quality and structural performance of the component can be guaranteed. In this contribution, effective solutions of multiple sphere detection and concrete surface modeling based on the technology of terrestrial laser scanning (TLS) during the casting process are proposed and realized by the Institute of Engineering Geodesy (IIGS). A complete monitoring concept is presented to acquire the point cloud data fast and with high-quality. The data processing method for multiple sphere segmentation based on the efficient combination of region growing and random sample consensus (RANSAC) exhibits great performance on computational efficiency and robustness. The feasibility and reliability of the proposed methods are verified and evaluated by an experiment monitoring the production of an exemplary graded concrete component. Some suggestions to improve the monitoring performance and relevant future work are given as well.

Holistic Quality Model and Assessment—Supporting Decision-Making towards Sustainable Construction Using the Design and Production of Graded Concrete Components as an Example

“…The necessary models describing the outflow dynamics are based on those derived in [59]. For both onlineand offline-calculated input trajectories, it is advisable to check after each layer if buoyancy can be avoided and whether layer height is being achieved to a sufficient degree of accuracy, thus necessitating another control point [60].…”

“…The values for MC were derived from reports [60] and the literature [61]. There are some values, which evaluate the feature without providing information for the individual underlying parameters (marked with [b]).…”

Application of Terrestrial Laser Scanning (TLS) in the Architecture, Engineering and Construction (AEC) Industry

“…To avoid failure during on-site construction, efforts should be made towards performing a comparison between the dimensional conformance of precast elements in as-designed status and as-built status. Research efforts have covered a wide range of precast elements, such as concrete elements (walls [ 56 , 71 ], columns [ 153 ], stairs [ 71 ], slabs [ 45 , 79 , 92 ], hollow spheres [ 155 ], bridge piers [ 66 ]), steel structures [ 47 , 156 ], pipes [ 154 , 157 ], and joinery products [ 152 ]. Obviously, the key point in dimensional quality inspection is that the fabrication model of precast elements constructed from point cloud data should be compared with the corresponding as-designed BIM model in a common coordinate system in order to identify dimensional discrepancies.…”