Integration of Discrete Reinforcement Elements for Shotcrete 3D Printing of Complex Structures (2025-12)¶

By applying the material layer by layer, Additive Manufacturing (AM) in construction eliminates the need for conventional formwork and allows for the fabrication of architecturally expressive designs as well as material-efficient geometries derived from structural optimisation algorithms. To date, the fundamentals of material application within the AM process has already been researched extensively. However, the integration of reinforcements into additively manufactured concrete remains a major challenge, especially with regard to embedding the reinforcements into highly complex and topology-optimised forms aligning with the resulting force-flow. With this background, this study explores three discrete-element-based reinforcement techniques tailored to the requirements of Shotcrete 3D Printing to enable continuous reinforcement within complex geometries: short rebar insertion, where straight rebars are inserted across the layer structure to form continuous vertical reinforcement by slight overlapping. 3D short rebar joining is a possible alternative, straight rebars are joint by welding in the force-flow direction. And finally, 3D bent rebar joining, where short rebars, pre-bent according to the forceflow, are joint by welding into a continuous structure. Each technique is discussed individually in terms of the process adaptability, process limitations and individual joining techniques based on the defined criteria. Additionally, a full-scale test during printing is performed to qualitatively evaluate the processes and respective limitations. A comparison reveals respective advantages and identifies potential combinations for complex printed geometries. On this basis, future research topics are enabled, such as forceflow oriented reinforcement layouts and their automated manufacturing methods to pave the way for the application as material-efficient and structurally optimised elements in the construction industry.