Integrating Mineral-Bonded Carbon Fibers into 3D Concrete Printing (2022-06)¶

The construction sector is in a process of rethinking: Away from ‘higher, faster, further’ (and cheaper!), toward sustainable, durable, environmentally friendly and highly digitalized and automated construction industry. Additive manufacturing with concrete, also called 3D concrete printing (3DCP) has emerged from these requirements. It enables formwork-free, robot-supported construction and saves resources through slim design. Integration of reinforcement into 3D concrete printing remains however a major challenge. The article at hand presents the recent work at the TU Dresden focusing on the integration of mineral-bonded and polymer-bonded carbon fiber heavy tows in additive manufacturing with concrete. The research work is part of the CRC/TRR 280 sub-project D01. In this technology, the continuous fiber bundles are impregnated with ultra-fine mineral suspension prior to merging them with concrete. The integration of carbon fibers into the 3D printing process has been investigated using two different approaches. The first one makes use of a gantry printer, which enables printing relatively large cross-sections with multiple integrated carbon yarns. The other one uses a sixaxis industrial robot arm as a manipulator for printing fine high-resolution structures with a high degree of reinforcement. This approach makes it possible to produce prefabricated 3D topologies with a highly branched inner structure. Such topological optimization stands for highly efficient use of resources, but it also poses special requirements with respect to concrete composition, such as set on demand, so that buildability can be ensured after fresh material is pumped and extruded.