Experts: Philippe Block (ETH Zurich), Benjamin Dillenburger (ETH Zurich), Moslem Shahverdi (Empa)
3D printing of structural elements and entire buildings could bring overdue disruption to the construction industry and revolutionise sustainable construction going forwards. Thanks to progressive framework conditions, internationally competitive research groups and market leaders in the field of material development, Switzerland could play a pioneering role.
Picture: iStock
3D printing is no longer limited to small parts: Increasingly large structural elements are being additively manufactured and bonded together. For instance, the technology has already been used successfully in China, Germany and the United Arab Emirates to print one- and two-storey buildings, and in Switzerland to print the pedestrian bridge Striatus, which stands in Venice. 3D printing is also suitable for the production of complex facade elements, flights of steps, and fittings. Recently, there has also been an increase in additive manufacturing of large complex plastic formwork shapes. 3D printing of large structural elements involves various procedures, in which, layer by layer, materials are extruded or applied in a powder bed. Depending on the material, these layers can be bonded using chemical or thermal processes.
Compared to conventional methods, additive procedures offer various advantages for the production of large structural elements. The basic idea is simple: faster, more efficient construction using fewer workers – an advantage that is not to be underestimated when there is a shortage of skilled labour. In complex or non-load-bearing structures, material is ‘inserted’ only where it is actually needed, as cavities are easier to produce. This reduces material consumption and grey energy. Developments in the construction sector have recently made it possible to use recycled concrete instead of emission-intensive high-performance concrete, a development that is having a positive effect on building sustainability. Currently though, this is only possible for small walls and curved structures that do not require reinforcing rods. Additively manufactured structural elements can also be produced at the very place where they are used. This reduces transport distances and logistics and thus improves sustainability. 3D printing of large structural elements is cheap and relatively simple, so it can take place anywhere in the world on a decentralised basis and represents a great opportunity to quickly realise construction projects in developing countries.
In the future, 3D printing will be increasingly used in the construction of buildings and bridges to save weight and material. Dubai, for example, has set itself the goal of printing 25 percent of all new buildings by 2030. The technology also has the potential to become a game-changer for the construction of buildings in inhospitable places, such as icy regions or outer space, as it can relieve humans in dangerous situations (see also Teamwork in the air).
Due to its progressive and innovation-friendly building regulations, Switzerland is optimally positioned to play a leading role internationally in the construction sector. However, this is offset by the traditional conservatism of the construction sector. There are opportunities for both academic research and industry. The National Centre of Competence in Research ‘Digital Fabrication’ ensures long-term prioritisation of this topic, beyond academic research. In addition, Switzerland is home to Sika and Holcim, two companies that dominate international development on the materials side.
There are several challenges on the technological side. Concrete for 3D printing has to be of very high quality, but this increases the concrete’s cement content and thus its carbon footprint. Overcoming this challenge requires cooperation between civil engineers and materials scientists. Reinforcing rods must either be integrated into the printed structures or replaced,otherwise the applications will remain very limited. Furthermore, since building materials and procedures are both new, there have been no long-term studies of the type needed for large-scale commercialisation. At the same time, the layer-by-layer structure that printing produces is at odds with the corresponding required level of continuity, such that the issue of earthquake safety comes into play. Maintenance, repair and recycling of additively manufactured structural elements are also topics that have to be addressed.
On the societal side, the benefits of the technology are offset by concerns about job losses in the construction sector. However, it is to be expected that new, more interesting jobs will be created.
Although 3D printers are expensive, they are a worthwhile investment for SMEs in the construction sector: In particular, the printing of formwork shapes for internal use or for sale pays off and there is a big market for it. In the future, there will be money to be made with other products, such as concrete furniture, garden accessories, flights of steps and complex walls. To make effective use of these printers though, companies will have to adapt their approach to products and the way they are manufactured. This requires specialist knowledge that will also be indispensable when optimising the material used. Alternatively, it is possible to contract out structural element printing. Providers can be found around the world, including in Switzerland.
One specific example application is described in the article Teamwork in the air.
