Formwork facing from the 3D printer

For the new construction of the Sächsische Aufbaubank (SAB) in Leipzig, a semi-circular staircase with intermediate platform was to be built, 40% of which is semi-mounted on a load-bearing wall and then self-supporting. The surface of the inner side was to be produced as fair-faced concrete with acidified surface, meaning that there would be no gravel nests or leakage of the fresh concrete. This all meant that high-precision formwork was required.

The uniaxially curved surfaces could be formed conventionally and economically. However, in the area of the three-axis curved surface, a special formwork required for this would have been relatively time-consuming both in terms of production and assembly. For this reason, Doka opted for an unusual approach: In cooperation with voxeljet, a supplier of 3D printing systems for industrial use, an additional manufacturing process was used to produce a special formwork facing for the special formwork. To do this, Doka's technicians first planned the seven formwork facing parts virtually. Using these detailed models, voxeljet used the powder binder jetting process to produce the formwork facing parts with a wall thickness of just 21 mm. The result was a plug system consisting of 3D-printed and CNC-milled elements and standard formwork. The employees required only about a tenth of the usual time to assemble this due to the high degree of prefabrication of the individual parts. The concrete result also spoke for itself: Thanks to the clean surfaces, no expensive corrections or repairs were necessary.