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KnitCandela is a thin concrete shell made with knitted formwork

KnitCandela is a thin, sinuous concrete shell built on an ultra-lightweight knitted formwork by a team of researchers of ETH Zurich, the Computation and Design Group of Zaha Hadid Architects and Architecture Extrapolated.

KnitCandela is a thin, doubly-curved concrete shell. Its centre is made of knitted fabric, a technology the researchers call KnitCrete, which was covered with 5 tonnes (5.5 US tons) of concrete.

KnitCrete is a material-saving, labour-reducing and cost-effective formwork system for casting of curved geometries in concrete. The formwork uses a custom, 3D knitted technical textile as a lightweight shuttering. Knitting minimises the need for cutting patterns to create spatial surfaces, allows for directional variation of material properties, and simplifies the integration of channels and openings, according to the research.

The formwork was knitted in Switzerland and transported to Mexico, where the shell is on display, in suitcases. The total weight of the formwork is only 55 kg (121 lbs) and 50 m2 (538 ft2) in size. The textile is made up of four long strips of double-layered, seamless textile ranging from 15 to 26 metres (49 to 85 ft) in length. Each of these pieces is knitted in one go.

The backside fulfils technical needs by including features for inserting, guiding and controlling the position of additional formwork elements, while the front, which remains visible, shows a colourful pattern.

Between each two layers, there is a pocket, which is inflated using standard modeling balloons. These inflated pockets become cavities in the cast concrete. This creates a waffle shell without the need for a complex formwork.

The shell is an homage to the famous Spanish-Mexican shell builder Félix Candela (1910-1997), reimagining his concrete shells though novel computational design methods and knitwear technology.

KnitCandela is built at the Museo Universitario Arte Contemporáneo in Mexico City as part of the first exhibition of Zaha Hadid Architects in Latin America from 20 October 2018 to 3 March 2019.

Photo credits: see photos