Sackfuls of shelter

Aid workers and troops in war zones and areas devastated by natural disasters could soon be using portable shelters that are better insulated and more robust than tents, thanks to two students at London’s Royal College of Art.

The Concrete Canvas, designed by industrial design engineering masters students William Crawford and Peter Brewin, is as durable as a prefabricated building but costs around a quarter of the price.

Last week, the design won the New Business Challenge prize from Imperial College, London and the Tanaka Business School. It can be assembled by an untrained person within 40 minutes and sets ready for use within 12 hours. Only water and air are required.

The shelter inflates to create a Nissen-hut shaped thin concrete wall that is robust and lightweight with a surface optimised for compressive loading like an eggshell. It can be used as offices and accommodation or be delivered sterile to house medical clinics.

The design has better thermal properties than canvas, and can be covered in soil or snow to improve insulation. Each shelter has an area of 16m2 of floor space, though a 30m2 version is planned. It is delivered in a sealed plastic sack and weighs less than 250kg, so several can be loaded on to a Landrover or light aircraft.

The structure consists of a cement-impregnated fabric that is bonded to the outside of an inflatable plastic inner. The sack is filled with water and left for 15 minutes to allow the fibre matrix to draw the water into the cement. The bonding agent is also hydrophilic. No measuring of water is needed as the volume of the sack controls this. The sack is then cut along its seams and unfolded to form the ground sheet.

A chemical pack is activated to inflate the plastic inner before the shelter is left to set. The fibres in the set concrete reinforce the structure, making it robust during earthquakes. It is designed to last at least 10 years. The two engineers have patented the concept and hope to bring it to full-scale production soon.