Combined additive manufacturing processes for reinforced concrete elements

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Additive manufacturing techniques enable the automated production of components of almost any shape and using various materials. As a matter of interest in construction industry, many research projects have focused on the production of unreinforced concrete components. In particular, in recent years numerous prestigious objects have demonstrated the potential of additive manufac-turing techniques for the construction industry.The next step in the development of this innovative manufacturing method is the fabrication of statically relevant components. In this context the integration of reinforcement elements is indis-pensable in order to transfer tensile forces arising from the load as well as to ensure ductile failure behaviour of statically relevant concrete components. When integrating reinforcement elements, the process must guarantee the flexibility and efficiency of additive manufacturing methods on the one hand and the effective exploitation of the reinforcement on the other hand. Hence, there is the need for developing combined manufacturing methods, which receive the freedom of design and provide a proper bond with the surrounding material at the same time.The aim of the submitted research project is the fundamental investigation and explorative-comparative assessment of combined additive manufacturing technologies for the automated integration of reinforcement elements into the additive manufacturing process of concrete components. Until now the state of research is still at the beginning and the large number of technology competitors is the motivation of simultaneous investigation on several technologies with the aim of an evaluation. There are several types of technologies for the exploration, which are developed and investigated simultaneously and experimentally on a laboratory scale. Based on that, production-related characteristic values (e.g. productivity) as well as component characteristics (e.g. strength) are determined experimentally and compared in a matrix-like overview. The need for fundamental research derives from the high combinatorial diversity of interesting reinforcement approaches with material efficient additive manufacturing techniques as well as the experimental evaluation of these technology combinations, which haven’t been investigated until now. As a technology method for the additive manufacturing of the concrete matrix two processes will be considered: a) extrusion-deposition 3D printing and b) Shotcrete 3D printing. For the production of reinforcement elements, a) the deposition of fibre rovings, b) the production of steel bars by means of an additive welding process and c) the robot-supported insertion of short reinforcement bars are comparatively examined. Due to the interdisciplinary cooperation in the fields of production automation (K. Dröder), design of component structure (H. Kloft) and materials science (D. Lowke), the required cross-domain research is enabled.