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.
Highlights
The production of a small-scale meso-graded concrete component was monitored in the laboratory of ILEK
A complete concept for monitoring the production process of meso-graded concrete components using terrestrial laser scanning (TLS) is proposed in this study, including automatic detection and estimation of the hollow spheres and surface modeling of the concrete level
The efficient combination of region growing (RG) and random sample consensus (RANSAC) algorithms is developed to segment the spherical points from the point cloud quickly after each scanning
Summary
One approach to reducing the weight of load-bearing concrete components is the use of graded concrete which was invented by Werner Sobek. This technology is based on a tailored design of the component interior [4]. Cavities of different shapes and sizes are arranged inside the component in such a way that a fully stressed design is achieved, which results in a full material utilization at every point in the component [4,5]. Compared to conventional concrete components, the weight of the graded component and the associated use of resources can be reduced by up to 50% with CO2 savings of 30–40% while its performance is fully maintained [6,7,8].
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