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Zurich – Researchers at the Federal Institute of Technology in Zurich (ETH) have created the world’s first full-scale architectural project using 3D sand printing for its formwork. The creation is a lightweight concrete slab.

ETH researchers have created a new 80-square-metre lightweight concrete slab with an ornamental design. But particularly unique to the project is the production method used. The researchers worked with a 3D sand printer that produced the formwork rather than the building components. Unlike the layered concrete printing process, it enabled high- performance, fibre-reinforced concrete to be used.

Formwork production is the most labour-intensive stage of concrete construction, according to the ETH – in particular for non-standardised components. The temptation is therefore to repeatedly produce the same solid ceilings, but the disadvantage is excessive material consumption and a big CO2 footprint.

With the 3D sand printing technique, it is much easier to produce geometrically complex formwork. The geometry can be adapted so that at each point it is applied only as thickly as structurally necessary to support the force flow. In the new slab, the researchers achieved a minimum depth of 20 millimeters.

To produce the formwork, the researchers developed a new planning software to record and coordinate all parametres relevant to production. “We didn’t draw the slab; we programmed it,” commented Mania Aghaei Meibodi, who was involved in the ETH project. “It would not have been possible to coordinate all these aspects with analogue planning, particularly with such precision.”

After a two-week hardening process, the 11 individual concrete segments were ready for transport to the ETH ceiling in the DFAB House. The building is a three-storey residential unit located in NEST, a research and innovation platform in Dübendorf run by the Federal Laboratories for Materials Science and Technology (Empa​​​​​​​) and the Swiss water research institute Eawag​​​​​​​.

“It was spectacular to see on the construction site how seamlessly our elements fitted with each other and with the existing components of the DFAB House,” commented project lead Benjamin Dillenburger. He explained that meticulous planning and pre-fabrication reduced time on the construction site to a minimum.