Various cooperation projects have already proven the effectiveness and efficiency of using 3D-printed formwork.
One of the first projects took place in cooperation with Züblin AG. For the "Stuttgart 21" project - in which Züblin AG is involved in several construction phases - columns with goblet shoulders are to be erected in the underground station. The special feature of this complex form is the double-curved surfaces in the upper section. A hybrid solution consisting of conventional formwork and moulds from 3D printing seemed to make sense here - also in terms of cost.
As a test, four formwork elements were printed at the voxeljet headquarters in Friedberg and infiltrated with epoxy resin. The 3D printed elements formed the contouring formwork, which was supported by a conventional girder framework. The elements were further processed and optimised to ensure efficient 3D printing. The total weight of all four elements was around 840 kilograms. 3D printing took about one day. Afterwards, the material had to be cured with epoxy resin, which also took about one working day. Finally, the formwork elements created using the 3D printing process Binder Jetting were erected and filled with two cubic metres of concrete. As the resulting concrete structure shows, the desired complex geometric shape was successfully produced.
Furthermore, the attachment of the formwork scaffolding, stripping and general handling of the printed formwork were successfully tested in this cooperation project. It was also demonstrated that the water-repellent formwork from the 3D printer can be reused without any problems, which makes this process even more economical. After several preliminary tests under laboratory-like conditions, only this large-scale test for a concrete application brought the decisive findings: The formwork can even be reduced to a thickness of 21 mm, which further reduces printing volume, weight and costs.
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