Design for 3D Concrete Printing : Optimisation Through Integrated Workflows

Sammanfattning: The transition from conventional cast concrete to 3D Concrete Printing (3DCP) marks a paradigm shift by directly depositing fresh concrete layer upon layer according to a digital model without the need for a formwork. This technology offers the possibility of achieving innovative and complex geometries in an automated process. Additionally, the implicit digitalisation introduced by this technology streamlines the interaction among different stakeholders, thereby reducing human errors and augmenting construction quality.Nevertheless, despite its potential, methods for fully exploiting the design capabilities of 3DCP are still largely underdeveloped. This is primarily due to the assumed separation between the design process and the generation of manufacturing instructions. While the current driver for this technology is linked to increasing productivity and reducing labour costs, its most significant contribution may well be in the manufacturing of material-efficient structures by automatically integrating structural analysis into the designprocess.This licentiate thesis aims to extend the design scope for this rapidly maturing technology by investigating its design possibilities, relevant printing parameters, and structural optimisation capabilities within the inherent restrictions of the process. The research focuses on the development of integrated design-to-manufacture workflows for the manipulation, analysis, and optimisation of print paths considering material and process constraints. Additionally, a comprehensive literature review is conducted, with a particular emphasis on the expansive design capabilities of 3DCP.Experimental studies encompassed the design, manufacturing, and testing of concrete prototypes using a custom-made 3DCP system based on a robotic arm. The results demonstrated that customised material distributions can be successfully programmed and executed, resulting in prototypes with enhanced structural performance. Laboratory tests on topology-optimised unreinforced 3DCP beams revealed a substantial increase in load-bearing capacity per unit weight compared to conventional 3D printing patterns. The thesis aligns with the broader sustainability goals of the construction industry. Even though the cement content in 3D printed concrete currently tends to be higher compared to conventional methods, the potential of the technology for optimising material use, minimising waste, and incorporating additional functionalities to structures presents significant opportunitiesfor reducing the environmental footprint of concrete construction. By integrating manufacturing constraints into the design process, this study delineates a pathway for extending the design possibilities of 3DCP toward the implementation of material-efficient structures with graded properties. Ultimately, this study contributes to bridging the gap between digital design and digital fabrication methods, thereby advancing concrete construction practices.