Entwicklung praxisorientierter Methoden für den 3D Druck des Verbundwerkstoffs Stahlbeton (2023-09)¶

In this paper, a novel 3D printing process for reinforced concrete structures called Additive Manufacturing of Reinforced Concrete (AMoRC) is proposed. The process consists of a continuous concrete extrusion process and an intermittent stud welding process, both carried out by a robotic arm respectively. The welding robot runs ahead of the concrete extrusion robot and produces the spatial reinforcement mesh from prefabricated reinforcing bar segments. A novel fork-shaped print head with four adjustable nozzles allows for concrete extrusion around the reinforcement with different diameters. By joining segmented rebars of limited length to a reinforcement mesh in the AMoRC process, the consumption of energy and time can drastically be reduced compared to shape welding. The length of the joined rebars can be adapted to the component geometry and the extrusion speed. The bar segments to be joined are kept ready in a magazine belonging to the print head, which enables the feeding of bars with different diameters to arrange a load-efficient and economical reinforcement mesh. The preliminary testing of the additively fabricated reinforced concrete components is also implemented to char- acterize the structural behaviour of those 3D-printed composite specimens. In the initial phase, the reinforcement installation was performed manually until the second robot will be added to the process and experiments were done to characterize the printed structures. The pull-out test is used to investigate the bonding behavior between reinforcement and printed concrete. The four-point bending test is also utilized to study the mechanical behavior of the printed reinforced concrete specimen in a larger scale.