Production of high-precision formwork elements using parametrically programmed concrete extrusion and machining

The paper presents an additive process for the sustainable production of recyclable formwork elements. The production is based on digitally planned concrete extrusion and milling in the fresh and also in the hardened state and the subsequent moulding of the model with casting resin. As part of the research, a clinker-reduced concrete mixture was developed and characterized. The clinker-reduced concrete is extruded close to the final contour to create the model for a formwork element. Afterwards the printed component is subjected to high-precision processing in the fresh and afterwards in hardened state of the concrete. Processing too early leads to smearing on the surface. Too late initial machining results in less possible infeed and increased tool wear. The resulting models are used for the production of flexible cast resin formwork elements. After using the extruded and machined formwork elements, a recycling process is applied and the recycled material can be fed back into the printing process. The resulting material cycle increases resource efficiency, which is the key to success for the sustainable production of precast concrete elements.