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40 CPI %u2013 Concrete Plant International | India Edition %u2013 5 | 2025 www.cpi-worldwide.comRecycling and reuse of the materialThe pre-shredded material was recycled using a turbo rotor. The resulting grain size distribution of the recycled material (0.05 % 160 %u00b5m, 1.45 % 90 - 160 %u00b5m, 10.5 % 45-90 %u00b5m, 3 % 32-45 %u00b5m, 95 % < 32 %u00b5m) is similar to the grain size distribution of the mineral flour used. This meant that the mineral flour could be replaced by the crushed recycled material, while the proportions of the other components were kept constant. Eligibility for extrusion was achieved up to a substitution rate of 50%. Characterisation of the compressive and flexural strength was carried out for substitution rates of 25, 50, 75 and 100 %. These strengths deviated by a maximum of 10 % from those of the original concrete recipe. This is an indication of the successful reuse of the recycled material and the realisation of a material circulation.Outlook - Demonstrator productionTo apply the technology, the planter is manufactured using the concrete casting process. Firstly, the outer formwork elements are produced conventionally from GRP. On the other hand, the core is produced using the near-net-shape extrusion technology developed as part of this research with subsequent milling in the fresh and hardened state. The model for moulding the core with a casting resin is quartered for production reasons. The extrusion and milling of a model element in the fresh state has already been successfully completed (see Figs. 4 and 6). In the further course of research, the model is milled into the final contour in the hardened state. The model is then moulded in a casting resin. A wooden core is fixed inside the mould element, which can be removed from the casting resin in a first step during demoulding. The thin-walled, flexible formwork element can then be easily demoulded, eliminating the need for a demoulding bevel and allowing the undercut to be produced.ConclusionsIn this research work, the successful development of an additive process for the sustainable production of a new formwork based on concrete extrusion and milling was demonstrated. A new fine concrete mixture with CEM III/A was developed and characterised, which enables processing in the fresh and hardened state. After the concrete elements have been extruded, they are shaped into their final form by brushing and milling. The new combined technology enables the resource-efficient and digitalised production of complex models without demoulding bevels and with local undercuts. After use as formwork, the recycling process of the concrete elements is continued and the recycled material is fed back into the printing process. The result is a complex technology consisting of the following steps: near-net-shape extrusion, brushing and milling in the fresh and hardened state, moulding with casting resin, production of precast concrete parts, recycling of concrete models, reuse for additive manufacturing. nBibliography & footnotes1. United Nations Environment Programme (2022). 2022 Global Status Report for Buildings and Construction: Towards a Zero-emission, Efficient and Resilient Buildings and Construction Sector. Nairobi2. S. Gelbrich, M. Absto%u00df, H. Funke: Complex concrete elements for the production of recyclable formwork by extrusion and milling, December 2023, ce/papers 6(6):729-734, DOI: 10.1002/cepa.2815 3. M. Absto%u00df, E. Rudolph, H. Funke, S. Gelbrich (2021) 3D printing and milling of complex concrete elements for the production of casting resin molds. In: CPT worldwide - construction printing technology, 2021. CPT Worldwide, Nr.: 2, 2021, S.14-20, ISSN 2629-15924. Gliniorz, R.: Energy-Efficient Reinforced Heating System Implemented as a Carbon Concrete Formwork. Springer Nature Switzerland AG 2023 Z. Zembaty et al. (Eds.): ECCE 2022, LNCE 322, pp. 258%u2013272, 20235. Lindner, M.; Scharf-Wildenhain, R.; Gliniorz, R.; Vanselow, K.; Funke, H.; Gelbrich, S.; Kroll, L. (2021) Kalibrierverfahren f%u00fcr konstante Materialstr%u00e4nge bei robotergest%u00fctzter Betonextrusion. Beton- und Stahlbetonbau 116, Sonderheft Schneller Bauen, 116, Ernst & Sohn 2021, pp. 42-47, ISSN 1437-1006. https://doi.org/10.1002/best.2021000516. Lindner, M.; Mandel, K.; Gelbrich, S.; Funke, H.; Kroll, L. (2021) Kontinuierliche Fertigung von d%u00fcnnwandigen faserverst%u00e4rkten Pr%u00e4zisions-Betonelementen f%u00fcr freigeformte Mo-dulbauweisen (KoBeMo). BetonWerk International Nr. 1, 2021, pp. 28-29, ISSN 1437-9023.chttps://www.cpi-worldwide.com/images/cpi/flips/2021/1/en/index.html?#p=28 7. Verein Deutscher Zementwerke e.V: Umwelt-Produktdeklaration - Portlandzement (CEM I), EPD-VDZ-20220153-IAG1-DE, 08.06.2022 8. Verein Deutscher Zementwerke e.V: Umwelt-Produktdeklaration - Hochofenzement (CEM III/A), EPD-VDZ-20220154-IAG1-DE, 09.06.2022FURTHER INFORMATIONSteinbeis Innovation Centre FiberCreteOtto-Schmerbach-Str. 19, Hall 12, 09117 Chemnitz, Germanysu1612@stw.de, www.fibercrete.deTechnical University of ChemnitzInstitute for Lightweight StructuresDepartment of Lightweight ConstructionReichenhainer Str. 33, Room 00809126 Chemnitz, Germanywww.leichtbau.tu-chemnitz.de/research-area/lbw/WASA AG Europaplatz 4, 64293 Darmstadt, Germany T +49 6151 7808500 info@wasa-technologies.comwww.wasa-technologies.com