Fabric Formwork for Concrete
To build a simple concrete wall, make two complicated wooden walls, pour the heavy grey liquid in between, and throw the wooden walls in the skip. This construction method is so ingrained it is rarely questioned, but it doesn’t make sense. It’s wasteful, and restricts form-making because it’s optimised for orthogonal design.
Sustainable design means thinking about how much control, or energy, we apply to material processes. The more control handed over to natural forces, the better. One way of achieving this is by casting concrete with fabric membranes – an alternative to traditional concrete shuttering that allows for more efficient and expressive structures.
Unlike traditional shuttering, fabric formwork uses tensile rather than compressive forces. Tensile structures weigh less and perform better than compressive equivalents, so the material required to resist tonnes of liquid concrete can weigh only kilos. And by utilising natural forces, material usage is minimised to form streamlined structural elements.
Interest in the technology is growing – a conference organised by the International Society of Fabric Formers was held in Manitoba, Canada, in May. Fabric formwork technology is actually very old – rammed earth within hessian sheets was first used 2,000 years ago. But a new generation of designers is reinventing it as a sustainable construction method for the 21st century – the work of three of them is introduced here.
Alan Chandler is the co-author of Fabric Formwork, shortlisted for the 2008 RIBA Research Award.