Integration of Mineral Impregnated Carbon Fibre (MCF) into Fine 3D-Printed Concrete Filaments

Additive manufacturing with concrete, also often called 3D concrete printing (3DCP), has been gaining land speedily in recent years. This technology not only opens up higher productivity and relieves labor of heavy work, but also offers completely new design possibilities. Here, novel architectural form languages and design approaches can be developed, which are based, for example, on growth principles learned from biology. The structures created in this way are characterized by a high degree of optimization with regard to material use. However, introduction of such approaches in the concrete construction requires an adequate reinforcement material and flexible technology for its integration into the 3DCP process. The article at hand presents a new technology developed for integrating such reinforcement into 3DCP. Mineral-impregnated carbon fibre (MCF) rowings are automatically introduced into the printing nozzle and subsequently centrally integrated into fine concrete filaments. In addition to the description of the fabrication process, the mechanical characteristics of the printed composite material are provided. For this purpose, both the stress-strain behavior of the composite and the bond properties between reinforcement and concrete matrix are investigated. Furthermore, a comparison is made between the performance of the printed material with reinforcement integrated in the concrete filament and a conventionally casted concrete. The evaluation of the results is accompanied by image-based examinations using computer tomography and scanning electron microscope to explain the effects of parameter under investigation on the bond quality and other properties.