KnitCandela: concrete formwork out of the suitcase

摘要

It appears that (digital) building is indeed returning to materiality, but this time no longer based on cultural history but on building technology. The project KnitCandela, which is seen as a homage to the Spanish-Mexican architect Felix Candela (1910-1997), was realized recently at the Museo Universitario Arte Contemporaneo (MUAC) in Mexico City. But whereas Candela had to use uniform hyperbolic and parabolic forms for his spectacular concrete structures, KnitCandela offers completely new possibilities: digitally fabricated knitted formworks which allow an equally efficient and precise realisation of free-form concrete structures. A five tonne, double curved concrete structure could be made in the space of just a few weeks, the textile formwork used to make it weighed only 55 kg, including tension reinforcement! Hardly any less fascinating is the fact that this knitted formwork could be brought to Mexico in a suitcase. KnitCandela is based on close cooperation between the Computational Design Gruppe of Zaha Hadid Architects, the Block Research Group of the ETH Zürich and Architecture Extrapolated. Alongside the computer-based design process it is above all the digital building process that stands out: to produce the formwork an industrial sewing machine was used. This machine could process more than 350 km of polyester threads in only 36 hours and allowed the textile formwork to be made in four individual strips, each consisting of two layers. The lower layer forms a coloured, patterned soffit that relates to the colourful textile art of Central America; the upper layer was made with pockets for the reinforcement cables and with hollow chambers. The strips of fabric were then stretched on site in a temporary frame and, by means of steel cables, were brought into their (three-dimensional) form. To stabilise and seal it the textile formwork was sprayed with a special cement mix. In the last step a standard fibre-reinforced concrete was applied. That a building system of this kind is not only very material-efficient and highly economical, as conventional formwork constructions are not needed, but also saves a considerable amount of time is shown by the speed with which this project could be realized. Only five weeks were required.