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38 CPI %u2013 Concrete Plant International | India Edition %u2013 5 | 2025 www.cpi-worldwide.comThe cured milling tests were carried out using a 5-axis portal milling machine. The use of absolute servo motors means that no referencing of the machine is required. Solid carbide ball nose end mills, roughing cutters, finishing cutters and milling heads with diamond inserts were used.Planning and programming of robot pathsGrasshopper, an add-on to the CAD software Rhinoceros%u00ae, is used to create extrusion programmes for the control and production planning of KUKA 6-axis industrial robots. Grasshopper is a visual programming tool for creating parametric geometries in Rhinoceros. The results are controlled algorithms that describe or define the geometries. KUKA|prc generates the final robot commands on this basis. The programmes for the extrusion and subsequent processing of near-net-shape elements essentially consist of the following steps: Creating the geometry or preparing the target geometry, creating the path curves and generating the robot commands.Results and discussionMaterial properties and CO2 savingsIn order to obtain a material that can be extruded and processed at the lowest possible cost, the Steinbeis Innovation Centre FiberCrete developed a microconcrete consisting of CEM III/A cement, a mineral powder with a grain size range of 0 to 200 %u00b5m, admixtures (stabiliser, primary and secondary superplasticiser) and water. The superplasticiser enables the water content to be reduced and, in conjunction with the stabiliser, ensures a more uniform mixture that is less prone to sedimentation. In a first mixing step, the solid raw materials are mixed for 140 seconds. The liquid raw materials are added and mixed again for 320 seconds. This two-stage mixing regime ensures complete mixing of the components into a homogeneous material. The slump could be characterised as 13 cm. Furthermore, the compressive strength of 40.01 MPa and the 4-point flexural strength of 6.01 MPa were determined experimentally.A CEM III/A with a volume fraction of 520 kg/m%u00b3 was used in the concrete mixture. According to current research, this recipe is comparable to a similar concrete mixture that was used with a CEM I with a volume fraction of 600 kg/m%u00b3 [2]. The value for the cement clinker emissions of Portland cement CEM I is 875 kg CO2/t cement clinker [7]. For CEM III/A cement, the CO2 emissions are 543.8 kg/t of cement [8]. This results in a saving of 282.8 kg CO2 per cubic metre of concrete used. This corresponds to a reduction of 46.1 % in relation to the cement emissions.Near-net-shape extrusion of the concreteThe aim of this study is the additive manufacturing of a model for the production of a flexible formwork element for the production of a planter as shown in Fig. 3, left.Through various extrusion tests to generate initial samples, it was possible to determine essential settings with regard to the printing speed as a function of throughput and material system. Furthermore, settings and parameters could be characterised with regard to starting and stopping behaviour. This is necessary to enable seamless extrusion of the material and avoid defects. Extrusion is possible with a die diameter of 10 to 25 mm, a layer height of 5 to 20 mm and a feed speed of up to 720 mm/min. The model element was then additively manufactured with a nozzle diameter of 20 mm, a layer height of 5 mm and a speed of 720 mm/min.Demonstrator with undercut for holding LED stripsFlexible formwork element with wooden coreModel elements structurally derived from the coreSingle model element for extrusion and millingFig. 3: Procedure for removing the formwork elements required to manufacture the demonstratorFig. 2: Milling heads of different degrees of hardness for processing fresh concrete