Created by Zaha Hadid Architects, this innovative project demonstrates the possibilities of using KnitCrete technology for creating curved concrete shells efficiently.
We've written for some time now about how a variety of digital fabrication techniques are changing the way we build and make things, whether it's 3D printing, or using robots and drones to weave structures.
Demonstrating the possibilities of using 3D-knitted formwork for creating ultra-thin and lightweight concrete forms -- without the need for expensive moulds -- Zaha Hadid Architects (ZHA) recently completed KnitCandela, an experimental pavilion that re-imagines the iconic concrete shell structures of Mexican architect and engineer Félix Candela. Watch here to see how it was done:
The project came about as a collaboration between ZHA's computation and design research group, ZHCODE -- which oversaw the structure's architectural design -- and Block Research Group (BRG) of ETH Zurich, which developed the KnitCrete formwork technology and supervise the structural design and construction system. As ZHA explains:
While Candela relied on combining hyperbolic paraboloid surfaces (‘hypars’) to produce reusable formworks leading to a reduction of construction waste, KnitCrete allows for the realization of a much wider range of anti-clastic geometries. With this cable-net and fabric formwork system, expressive, freeform concrete surfaces can now be constructed efficiently, without the need for complex molds. KnitCandela’s thin, double-curved concrete shell with a surface area of almost 50 square metres (538 square feet) and weighing more than 5 tonnes, was applied on a KnitCrete formwork of only 55 kilograms (121 pounds).
According to the design team, the KnitCrete formwork uses a custom-designed, 3D-knitted technical textile as a lightweight vertical formwork, using over two miles (3.2 kilometres) of this special yarn that is machine-knitted into four seamless, double-layered strips measuring between 15 and 26 metres (49 and 85 feet). These strips were hung from a wooden frame using a tension cable-net system, and then 1,000 modelling balloons were then inserted in between the two layers to create the final shape. The exterior was then coated in a special cement paste to finalize it as a rigid form. The team says:
The pockets created between the two layers as part of the spatial knitting process are inflated using standard modeling balloons. These inflated pockets become cavities in the cast concrete, forming a structurally efficient waffle shell without the need for a complex, wasteful formwork. Pockets located on this exterior side of the textile have different knit densities to control the inflated shape and openings for the insertion of the balloons, enabling cavities of different dimensions to be created with one standard balloon size.
As the team notes, this method lessens the need for extra support structures and scaffolding. It's extremely easy to transport, so much so that in the case of this structure, the feather-lightweight knitted formwork was actually carried from Switzerland to Mexico in a suitcase. KnitCandela is currently being exhibited at the Museo Universitario Arte Contemporáneo (MUAC) in Mexico City. See more over at Zaha Hadid Architects.