An exploration into the stability of 3D printed thin-walled concrete elements during manufacturing is presented. The failure mechanisms, material parameters and analysis methods are presented. Self-buckling is the dominant failure mechanism, where the Young's modulus plays an important role. Material experiments to assess the Young's modulus are performed and presented. Predictive analysis methods to evaluate the printability of objects are discussed, where finite element modelling and the mechanistic model of Suiker are compared.

The novel technique of 3D Concrete Printing (3DCP) shows great potential in the reduction of labor and material as well as the fabrication of freeform design. Different research institutions and companies recognize this potential and have set up printers to further investigate and develop the technique all over the world. Some pioneering projects showcase the state of the art by producing full scale structures, but otherwise printing of concrete is done mostly in a research lab. In an effort to find whether 3DCP is ready for the current market of the building industry, this thesis performs a viability analysis on the production of façade panels by 3DCP. This research is performed for the University of Technology Delft and Movares Nederland B.V. using the concrete printer from Bruil. The origins of 3DCP are defined by the development of Additive Manufacturing (AM) in other materials (plastics) as well as the demand for freeform concrete production. Both fields are examined to help understand from where the technique is derived and what its goal and potentials are. Next to the initiators, some of the more advanced researches on the topic are disclosed in order to define the current level of capability of concrete printing. As this research focusses on testing the viability of 3DCP as production technique for structural verified elements, a case study is performed. Façade design is chosen as the design scope in order to consider the potential benefit of freeform design as well as integration of functions, which are both prominent in a building enclosure. Through analysis of façade designs, typologies and performance requirements, a concept design of a perforated façade panel is defined. Over the course of the case study the fabrication technique and the engineering model influence the design of the panel, and this design process is analyzed for the disciplines of design, engineering and fabrication. The façade panel is designed parametrically to allow façade patterns to be created by customized elements on mass-production scale (mass-customization). This sets the requirement for the engineering models to also be parameterized, for this a software strategy is defined. Specimen are printed and tested to define material properties of printed concrete and analyze the effect of the additive manufacturing method on the strength and concrete development. Additionally, different forms of reinforcement are implemented in the 3DCP production process and tested on fabrication and structural aspects. Finally, the case study element is produced and load-tested to conclude the research on the feasibility of fabricating and engineering a façade panel by 3DCP. This thesis proves that the technique can produce elements from which the structural behavior (load bearing capacity and failure behavior) can be safely predicted.