The building renovation process often throws up difficult challenges. Geiger Group found itself in such a situation as it approached the restoration of a listed building in Kempten in southern Germany. Geiger specialises in property development, construction, civil engineering and more. This restoration project - the conversion of an old brewery into an office and events space - was one of numerous similar projects the group carries out per year. The challenge facing the company was to replace five large stone window frames on the property, whilst retaining the impressive original aesthetic.
In replacing these stonework elements, there were two standard options that Geiger could have considered. The traditional method would be stone masonry. This is a highly skilled activity that produces exquisite results, however it is time-intensive and costly. The second option would be to cast concrete from a resin-coated foam formwork. The depth of the pattern meant that milling a single piece of foam to the desired shape was not possible, and production using several pieces would have increased costs and extended the duration. A more general drawback to this method and process is the toxicity and waste involved.
Since the project was on a tight schedule, Geiger reached out to NOWlab@BigRep, to explore a third option. NOWlab is the research and innovation hub within BigRep that endlessly searches for new ways to scale and shape additive manufacturing for tailored industrial use cases. NOWlab's team of experts work to create custom industrial application solutions advanced production methods and processes. As a key player in the research sphere, NOWlab is leading BigRep’s journey to discover the future of industrial manufacturing and products.
After discussing possibilities, NOWlab and Geiger agreed to collaborate on the windows and they produced them through the following process.
Geiger provided NOWlab with CAD files containing full specifications of the frames. NOWlab worked from these files to generate a digital pattern for a cast formwork. They then printed the formwork on a BigRep ONE, taking advantage of its 1m3 print volume to do this in one print.
The printed formwork, made from biodegradable PLA, was then sent to a fabricator to cast concrete sections. Assembly of the window frames from various sections was performed on the construction site, prior to a successful installation.
Although in this case the client provided CAD files, in another scenario NOWlab could have produced these, either creating a rendering from scratch or making a 3D scan of a template piece.
Geiger estimates the elements produced with NOWlab cost 50% less than they would have from a stonemason, with a production time shorter than 45% compared with if it had opted for resin-foam cast production. Geiger was also able to considerably reduce staff resources needed for the project. Combined with a high-quality finish, this was the perfect 3D-printed solution.
Products for the future
Over time it seems probable that Geiger and others will increasingly adopt these methods in their renovations. However, reconstruction is only one way to apply the basic technique.
NOWlab is developing 3D-print based concrete casting processes for architectural elements of the future. For the creation of both architectural facades and load-bearing, structural elements. With test-case projects underway, NOWlab has a patent pending for the production of 3D-printed formwork for this technology.
The advantages of production speed, reduced cost, and environmental soundness apply similarly to these applications. However with new products, the flexibility of the print process unlocks huge design potential. We can expect elaborate new surface textures, exterior forms and structural characteristics in designs freed from existing constraints. In this way 3D-print-based concrete casting offers a vision for the future of construction – for projects such as Geiger’s, which restore and revolutionise our landscapes. The BigRep ONE is helping that vision to fast become a reality.