Today, the majority of research in 3D concrete printing focuses on one of the three methods: firstly, material extrusion; secondly, particle-bed binding; and thirdly, material jetting. Common to all these technologies is that the material is applied in horizontal layers. In this project, a novel 3D concrete printing technology is presented which challenges this principle: the so-called Injection 3D Concrete Printing (I3DCP) technology is based on the concept that a fluid material (M1) is robotically injected into a material (M2) with specific rheological properties, causing material M1 to maintain a stable position within material M2. Different to the layered deposition of horizontal strands, intricate concrete structures can be created through printing spatially free trajectories, that are unconstrained by gravitational forces during printing.
This project aims for developing a structural-, and fabrication-informed design methodology that integrates design, optimization, and fabrication from the early design phase. In the first step, the research is pursued by generating a novel method for automatically finding the robotic path-planning. It will be followed by combining with design method based on graphic statics, which accounts for the constraints of I3DCP. Then several physical prototypes will be validated in various scales with different sizes of operating system including a micro setting. Furthermore, some optimization programs will be developed based on the results of the previous experiments in order to make the make the design process more intuitive and interactive. Reinforcement structures will also be considered to add in both design and fabrication steps. The whole methodology will be used for the construction of a final demonstration.
The underlying concept, to continuously extrude material in spatial trajectories, was previously investigated with other materials, with and without a supporting medium. These initial successes using polymers triggered testing of the concept with cement-bonded materials as well. For example, in 2019 the French start-up Soliquid published a video of extruding a concrete in a container filled with gel. Another team of researchers from Singapore University of Technology and Design (SUTD) robotically injected a reactive gas-forming powder, into a flat formwork filled with concrete, in order to create porous building elements. These experiments concurred with the initial experiments at TU Braunschweig and the filing of the multi-material patent “Injection 3D Printing”. From the outset, the concrete-based I3DCP research at TU Braunschweig aimed to create a coherent system and to develop material combinations that make multi-material versions applicable for the construction industry.
Project co-supervisor:
Co-supervised:
01/2020 - 12/2023
Print path of the intricate spatial concrete structure can be aligned with complex spatial stress trajectories, which can be simply treated as strut-and-tie networks. In this regard, a design framework called Combinatorial Equilibrium Modelling (CEM), grounded in vector-based 3D graphic statics and graph theory, lends itself particularly effective for designing spatially complex, lightweight, and material-efficient structures, which can then be realized using I3DCP. Considering the fabrication process, there are other constraints except for gravity as feedback from the experiments, a serious of optimization programs will be developed based on the CEM framework.
Prof. Dr. Norman Hack; M. Sc. Yinan Xiao; MAS. (arch & dfab. ETH) Noor Khader; Dr. Aileen Vandenberg