People in Brumunddal, Norway, remain rooted to the spot in astonishment, gazing up at a tall building standing around 85 metres high: a record for Norway, the Mjøstårnet is built entirely from glulam. Dutch architect Marco Vermeulen wants more and is working on the ‘Dutch Mountains’: he is planning the world’s tallest timber building with two towers, each measuring up to 130 metres in height. Milwaukee is home to a hybrid building called Ascent: a combination of wood and concrete with a height of 87 metres. Can concrete alone keep up? Especially when it comes to sustainability: wood sequesters CO₂, is renewable and revolutionising construction methods and the construction industry with its possibilities for precision manufacturing. And concrete?
First there is one big problem, which is actually two: concrete is becoming scarce because sand is running out. AND Production drives the emission of CO₂. The CO₂ emissions generated by the manufacture of cement are already three times higher than global air traffic. Nevertheless, various forecasts predict that the space built up with concrete will double in size by 2060. Is it possible or even ‘allowed’ to use concrete for building? What could be done to make concrete construction more climate-friendly going forward? Or are we in a hopeless predicament with concrete?
If something becomes scarcer than one would actually like, less of it needs to be used. Simply put, this is the ‘formula’ for gradient concrete. “Building research has been working hard on lightweight constructions for years. The interest in lightweight construction is not really a surprise: after all, the area presents great opportunities for the building sector in tomorrow’s world. The approach comes with very significant potential to cut back on the use of materials and energy in the production, transport and processing of building materials. It would also considerably improve the building sector’s carbon footprint.” (baustoffwissen.de)
So are we looking at a fluid change in concrete as the ‘favourite building material’ and different porosities, depending on the function and requirements? Does the future lie in harnessing the potential from the varying properties of the same material? “Gradient concrete could play a role in everyday construction methods going forward. Its use in components for ceilings and beams seems particularly promising. But the technology is also interesting for load-bearing exterior walls. For example, walls made of gradient concrete – which are very dense and load-bearing in their outer areas but at the same time contain a more porous ‘insulating core’ in the centre – could be used as a slim alternative to multi-layer composite heat insulation systems. Among other things, this would come with the additional advantage of recycling the walls later on according to type.” (baustoffwissen.de)
Conserving resources and considering aspects of the circular economy – this really does seem like a way to escape the dead end. Although still in its infancy, another process for handling concrete also seems very exciting and auspicious: ‘concrete layered extrusion’ for 3D printing with concrete. With this method, a house could ‘simply’ be printed. The benefits: it would same time any money, ensure greater design freedom and improve the environmental impact due to the use of less material and the production of less waste.
As mentioned at the beginning, wood has two very decisive advantages –and they are almost ‘killer arguments’ compared to the dual core problems of concrete: wood is renewable. And wood sequesters CO₂. The use of wood is being fuelled by ever-improving manufacturing and application processes. The consequence: project developers and architects around the world are currently having a great time planning and working with wood. There is no other way to put it: “Global skylines in transition – timber high-rises that sprout from the earth like plants are conquering the world of architecture (…) The innovative technology overcomes challenges such as acoustics and fire protection. From Norway to the USA, the trend towards sustainable building is inspiring architects around the world to break records and redefine construction methods of the future.” (WELT Doku – Stories and reports/
Experiments are also underway with bamboo. The 18th Venice Biennale of Architecture in 2023 showed, for example, how to approach new building materials and the future of construction from an African perspective. As is so often the case, both materials will be embraced in the end. With considerable flexibility and innovative strength as the supportive, connecting elements.
Further reading:
Baustoffwissen: Gradient concrete
https:/
Concrete 3D printing production process
https:/
18th Venice Biennale of Architecture: