Various cooperation projects have already proven the effectiveness and efficiency of the use of 3D printed formwork. One of the first projects took place in cooperation with Züblin and MEVA. For the „Stuttgart 21“ project - in which Züblin is involved in several construction phases, amongst others with complex funnel shapes that are to be created in the underground station. The uniqueness of these complex forms are the double curved shapes, especially in the upper section. A hybrid solution consisting both of conventional formwork and 3D-printed molds was implemented to receive a first large prove of concept.
As a test, four formwork elements were printed in the voxeljet headquarters in Friedberg and infiltrated with epoxy resin. The 3D printed elements formed the contouring formwork, which was supported by conventional wooden frames which were easily attached to the printed formwork. The elements were further processed and optimized in order to ensure efficient 3D printing on a VX4000 platform. The largest of all four elements, printed in one piece had dimensions of 1980 x 1082 x 289 mm. The 3D printing process took about one day. Subsequently, the material had to be hardened with epoxy resin. Finally, after the completion of the printed formwork elements they were filled with two cubic meters of concrete. Like the pictures below show, the desired complex geometric shape could successfully be produced.
Furthermore, the installation of the formwork, dismantling and the general handling of printed formwork was successfully tested with this collaboration under construction environment. It was also possible to prove that the water-repellent formwork from the 3D printer can be reused without any problems, which makes this process even more economical. This large-scale test brought the decisive requirements for concrete casting applications using 3D printed formwork:
The printed formwork elements need to be reduced in terms of thickness, resulting in a further descent of print volume, weight and costs.