3D concrete printing of solid wall cross-sections with truck-mounted concrete pump - a report on the first printed structure in Germany

The 3D concrete printing process offers the potential to replace traditional construction methods, particularly in view of increasing design and quality requirements and the shortage of skilled workers. An innovative concrete printing process called KARLOS has been developed in collaboration between Ed. Z & Uuml;BLIN AG and Putzmeister Holding GmbH. The method involves an automated truck-mounted concrete pump that extrudes concrete through a special print head to print load-bearing walls without formwork or subsequent compaction. The first real construction project was completed at the end of 2023 on the premises of STRABAG BMTI in Stuttgart-Weilimdorf in the form of a warehouse. A 10 x 6.5 x 5 metre warehouse with a total of 35 running metres of load-bearing and space-enclosing exterior walls as well as a surrounding attic was printed. A standard-compliant concrete acc. to DIN EN 206-1 in conjunction with DIN 1045-2 was used to manufacture the warehouse using the KARLOS-3D printing technology. This allowed the 3D-printed walls to be designed acc. to the specifications of DIN EN 1992-1-1 Part 12 for load-bearing structures made of unreinforced or lightly reinforced concrete. This approach was confirmed by various tests, including large-scale element tests at the Materials Testing Authority (MPA Karlsruhe) of the Karlsruhe Institute of Technology (KIT), to assess the static and fire protection properties. The project shows great potential, which should be further utilised in future construction projects.