Earlier this year, TCT reported on ETH Zurich’s Block Research Group (BRP), which has found its footing on what they hope is a stepping stone in the journey to the commercial use of its rib-vaulted geometry-reliant 3D printed sand floor structures. The researchers face the sternest phase of their challenge yet, that is convincing players in construction and architecture that the technology behind its structure is reliable. They might want to look north, to the capital city of one of its neighbours across the border, to garner some inspiration.
“This is one example of how an initial idea can turn into a fully developed product,” begins Jörg Petri, the Director of Innovation at NOWlab, the innovations and solutions centre of Berlin-based BigRep. His initial idea was born from a research project he was busy with over two years ago at the ITE in Brunswig. It centred on how the 3D printing technology could be utilised to improve the concrete casting of functional, dependable structures.
Petri remembers being in the position BRP find themselves in. The main factor in his ‘Print Cast’ idea evolving from research to real-life product was the willingness of GEIGER GmbH, a construction company in Germany, to take a risk. And it was a risk, because NOWlab had never before tested the idea on a real building site. The task was to recreate five window frames of an old brewery in Kempten, South Germany, a listed building which was developed with masonry techniques. With only five of the building’s windows needing renovation, GEIGER wanted to make sure the new window frames, made from concrete rather than stone like their original construction, would be identical.
An example of a structure which has had its design influenced by NOWlab's water soluble PVA material
Having approached NOWlab, and taken the measurements, conducted scans and modelled the full construction of the window frames, GEIGER allowed Petri’s team to calculate how much material and time they would need. The calculations were made at the end of March. Two months later the project was finalised, all windows in place, and the building ready to be used as an office and events centre.
“That was convincing for the team at GEIGER GmbH,” Petri told TCT. “We were the only ones at that point on the market to be able to 3D print a formwork in this scale and create these elements in a very short timeframe. They took the risk and it actually developed really well.”
The process began with Geiger scanning and modelling the window frames, before NOWlab 3D printed the negative cast forms on the BigRep One platform. Then the forms were passed onto Concrete Rudolph GmbH, who took charge of the pre-fabrication of the concrete elements. Finally, the segments were taken to a masonry where they were post-processed, ensuring the aesthetics of the structures were suitably identical to the old window frames, and then fitted onto the building.
A negative cast from the window frame printing on the BigRep One
All parties are happy with the outcome, yet it only shows off some of what NOWlab can do with this technique. A research project digging deeper into its potential is live, and the group has developed a water soluble PVA material, unharmful to the environment, and able to be put into normal water circulation. This material enables concrete to be casted around the PVA deposit, and when it is washed away, hollow structures are created. As architecture progresses, NOWlab is sure there’s room in the market for this faction of their technique too, and are working to improve the material. “We are working on optimising [the water soluble] material because it is made for support structures, it’s made to be washed out, but we are still developing a special material that could be better utilised for concrete parts so that it can be washed out faster, and it could be more stable. There is still a bit more development necessary but we have a demonstration in the pipeline which we will be presenting in mid-September.”
The demonstration will present the full potential of NowLab’s ‘Print Cast Formwork’ idea and the water soluble materials that are in development alongside it. Petri says the demo will be about 2.5m high, and 2-3m wide, and hopefully convey how formwork 3D printing can change construction techniques.
The PVA material is washed away to leave the hollowed indentations in the concrete structure.
During his initial research, Petri found a real need for 3D printed formwork. Innovative building design is more and more often featuring curvatures, as opposed to the traditional rectangular shapes. He names the London Aquatics Centre, used for the 2012 Olympics, and the Mercedes-Benz Museum in Stuttgart, as prime examples: “When we start to develop concrete elements that are moving out of the more rectangular geometries then the use of 3D printed formwork becomes feasible,” he reasons. “If this new technology becomes market proof, non-standard, form active and sustainable concrete elements can become the standard.”
Yet, more testing and research is required to get there. Though Petri’s initial project has ascended into its practicing in the real world, thanks to the daring of GEIGER, his team is striving to expand the scope further, and for good reason.
“This new technique enables more freedom for the designers and engineers to actually realise complex concrete structures that were much too expensive in the past,” Petri concludes. “We are quite positive that the overall 3D printed ‘Print Cast Formwork’ idea enabled through 3D printing will grow, and that the demand is already there.”
