Photo Courtesy of William Crawford and Peter Brewin

Designed by Peter Brewin and Will Crawford, Concrete Canvas has won 9 awards including the New /Business Challenge and Deutsche Bank Pyramid Award. It is backed by the Selected Works Scheme at the Royal College of Art. A patent has been filed. Crawford Brewin Ltd. is working to bring Concrete Canvas to market. They are currently seeking financial backing to develop the technology from working scale prototypes to fully detailed pre-production prototypes, this will take 10 months from funding.

The Need
Concrete Canvas (CC) has 2 major advantages over tents:

1. Operational: CC enables a hardened structure from day one of a crisis. It provides much better protection in extreme climatic conditions, better security against looting and enables otherwise impossible medical procedures.
2. Financial: CC has a design life of over 10 years, whereas tents only survive for 2 years and must be replaced. Therefore, Concrete Canvas is a one stop solution, saving effort and costs over the lifetime of medium to long term operations.

Photo Courtesy of William Crawford and Peter Brewin


Key Facts

• Rapid: enables users to produce hardened structures within a few hours, with
  comparable labour to a tented structure.
• Insulating: the concrete shell has good thermal properties and can be covered in earth or snow for increased insulation.
• Durable: far more durable than tenting with a minimum design life of 10 years.
• Secure: provides a level of security not possible with soft skinned structures, protecting stores and equipment.
• Sterile: can be delivered sterile; allowing previously impossible surgical procedures to be performed in situ from day one of a crisis.
• Strong: the low mass and fibre matrix locked inside the concrete, gives the structure good earthquake performance. The compressive structure means it can also be covered with sand bags, earth etc. to provide protection against shrapnel.
• Semi-Permanent: provides all the benefits of a permanent structure without the associated costs and time delays.

How Concrete Canvas Works

CC is a rapidly deployable hardened shelter that requires only water and air for construction. It can be deployed by a person without any training in under 40 minutes and is ready to use in 12 hours. The key to CC is the use of inflation to create a surface that is optimised for compressive loading. This allows thin walled concrete structures to be formed which are both robust and lightweight. CC consists of a cement impregnated fabric (Concrete Cloth) bonded to the outer surface of an inflatable plastic inner. It forms a Nissen-hut shaped structure with over 16 m2 of floor space, the technology can be scald to provide larger structures. The stages of deployment are as follows:


Delivery

CC01 comes delivered folded in a sealed plastic sack. The dry weight is 230kg, an 8 man lift and light enough to be transported on a pick-up truck or light aircraft.

Hydration

The sack is positioned and filled with water¹. The volume of the sack controls the water: cement ratio eliminating water measurement. The bag is then left for 15 minutes while the cement hydrates, this is aided by the fibre matrix which wicks water into the cement. Once hydrated, the sack is cut along its seams it then forms part of the ground sheet. Deployment is done at dusk to avoid over drying the cement.

Inflation

The structure is unfolded to form the shelter's footprint. A chemical pack is activated which releases a controlled volume of gas into the plastic inner and inflates the structure.

Setting

The concrete cloth cures in the shape of the inflated inner and twelve hours later the structure is ready to use. Doors and ventilation holes are left with no concrete cloth bonded to the plastic skin this allows access points to be easily cut from the inner once the cement has dried.

The fibres of the fabric form a coherent fibre matrix within the concrete providing tensile reinforcement. This greatly improves the composite strength of the shelter providing a durable protection with a design life of over ten years. Because the structure can withstand a very high distributed compressive load it is possible to pile snow, earth, sandbags etc on top. This enables excellent thermal properties and can provide protection against shrapnel, blasts and small arms.
Once CC has fulfilled its primary application as an emergency shelter, it is highly likely that a secondary use would be found for the structure. During field research we found a multitude of secondary applications such as agricultural storage and accommodation. CC can, however, be demolished using basic tools. The thin walled structure has a very low mass, leaving little material for disposal.

¹ Water does not need to be potable but must not be sewage or sea water, volume is 120lts = 12 persons' daily UN water ration.

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