From confectioners to robots – Tor Alva in Mulegns is unveiled

Summary

Digital craftsmanship The form of the structure is reminiscent of an ornate layered cake – a reference to the emigration history of confectioners from Graubünden who exported their skills from here to the whole of Europe. Thirty-two sculptured white concrete columns rise up over four storeys, becoming thinner and more branched, before fanning out in an almost tree-like fashion to form the domed space at the top. The tower was designed by architect Michael Hansmeyer and ETH Professor of Digital Building Technologies Benjamin Dillenburger. Instead of relying on traditional concrete formwork, they opted for an additive manufacturing process, whereby an industrial robot applies the concrete layer by layer into free-form elements without any supportive casting moulds. The design is based on complex algorithms that generate the ornamental and the structural aspects at the same time. New concrete, new technology To make this process possible, a specially developed concrete was needed. It had to be soft enough to bond the delicate structures, while hardening quickly enough to support the subsequent layers. Robert Flatt, ETH Professor of Physical Chemistry of Building Materials, developed a novel mixture for this purpose. Just before the concrete leaves the pressurized nozzle, two additives are blended into the mixture, allowing the characteristic droplet-like relief on the columns to be achieved. Two robots working hand in hand What is special about this project is that the 3D-printed elements not only serve as a shell, but for the first time they are also load-bearing. Until now, a suitable method to reinforce 3D-printed concrete effectively has been lacking. This is now possible thanks to a newly developed reinforcement concept implemented using a robot-assisted innovation. While one robot applies the concrete in layers, a second places a ring-shaped reinforcement in the new structure every 20 centimetres. This horizontal reinforcement in the form of rings is supplemented...