Philippe Block

"Design as Second Nature," a new exhibition at the Museo Universitario Arte Contemporáneo (MUAC) in Mexico City, features 40 years of Zaha Hadid Architects' (ZHA's) research in design and construction technology. As part of this exhibition, ZHA's Computational Design (CODE) research group collaborated with the Block Research Group (BRG) of ETH Zurich, and Architecture Extrapolated to design and construct a 13-foot-tall, thin-shell, double-curved concrete structure that pays homage to work of late Spanish-Mexican architect and structural artist Félix Candela Outeriño and is reminiscent of the colorful traditional dresses of the Mexican state of Jalisco.

Called KnitCandela, the experimental structure's dynamic, hyperbolic paraboloid form was created using a 3D-knitted formwork technology developed by the BRG co-directors Philippe Block and Tom Van Mele and Ph.D. student Mariana Popescu, in a collaboration with ETH Physical Chemistry of Building Materials group's Ph.D. student Lex Reiter and professor Robert Flatt, as part of Switzerland’s National Centre of Competence in Research project.

Lex Reiter
Maria Verhulst

The formwork's shuttering—a temporary structure used as a mold in which fresh concrete is poured—was constructed from four 3D-knitted, double-layered, fabric strips, ranging from 49.2 feet to 85.3 feet in length. Each strip comprises sleeves for the formwork's supporting cables and pockets for balloons (to create hollow spaces to save on materials and reduce the overall structural weight). According to Block, it took a flat-bed knitting machine 36 hours to finish knitting the stripes, which then were transferred from Switzerland to Mexico with two suitcases.

Mariana Popescu

As the next step, the formwork was stretched between KnitCandela's temporary boundary frame, and sprayed with a thin layer of cement. Once it hardened, the team covered the exterior layer with fiber-reinforced concrete, leaving the textile-covered interior surface exposed. Measuring 19 feet square and 13 feet tall, the 11,023-pound structure is supported only by a 122-pound knitted framework. The entire project took less than three months to complete, Block told ARCHITECT via email.

Juan Pablo Allegre

Using the BRG-developed technology had several advantages over conventional methods. "Knitting minimizes the need for cutting patterns to create spatial surfaces, allows for the directional variation of material properties, and simplifies the integration of channels and openings ... [such as] insulation, reinforcements, electrical components, and technical systems for heating and cooling," according to a BRG press release. The research, according to an ETH press release, shows using the knitting method, as opposed to milled formwork, in similar projects could reduce required materials, waste, time, labor, and costs, and more importantly, could help simplify the construction process for such complex structures.

KnitCandela will be on view until March 3, 2019, at the Museo Universitario Arte Contemporáneo in Mexico City.

Leo Bieling
Juan Pablo Allegre

Last year, the BRG made headlines for its 25-foot-tall prototype for HiLo, an ultra-thin, lightweight, and double-curved, concrete roof.