The ‘Building in a Bag’

Inflatable concrete shelters are a good fit across a broad spectrum of applications.

By Thomas Goodall

It is hard to imagine a self-supporting structure made of fabric, which can last for over ten years in varying conditions around the world, but they do exist. The shelters can be erected anywhere from war zones to disaster areas. They were invented by two university students back in 2005.

William Crawford and Peter Brewin were studying Industrial Design Engineering at Imperial College London and Royal College of Arts when the two students came up with the idea of creating a fabric which could act like a plaster cast, creating a solid material which could be used to create inflatable, semi-permanent shelters for disaster relief. Having finished university, they continued to work on the concept and formed the company Concrete Canvas Ltd.

The idea behind the design was to provide a more secure alternative to traditional large-scale tents and shelters which are used by organisations such as NATO in humanitarian disasters.

When the shelter arrives on site, it is encased in a sealed polyethylene bag, which is airtight and waterproof to stop any rot affecting the product. To further protect the shelter, the polyethylene bag is encased within heat treated timber and ply panel crates.

Two sizes of the shelter are available, the smaller 25m2 (CCS25) and the larger 50m2 (CCS50). Should the situation require, multiple Concrete Canvas Shelters (CCS) can be joined together to form larger structures, as the shelters have been designed to work as part of a modular system.

Because the shelters were designed to be deployed in disaster areas, they needed to be set up quickly so they could be used as soon as possible. For that reason, both sizes of CCS can be set up by just two people. For the larger CCS50, a vehicle or winch is required to aid the unfolding of the shelter from its packaging.

The shelters are given their shape due to the innovate nature of their design – rather like a Nissen hut. Both sizes contain an inflatable inner which is bonded to the Concrete Canvas material on the outside. Using a blower, the inflatable inner pushes the outer material into shape. Once fully inflated, the shelters are pegged down to secure it to the ground, and they are ready to be sprayed with water.

This may seem counter-intuitive, but this is where the speciality of the Concrete Canvas material comes into its own. As the material is a Geosynthetic Cementitious Composite Mat (GCCM), which contains a specially formulated dry concrete mixture, to harden the fabric you hydrate it and leave it to set. The shelters do not require fresh or bottled water to be used to hydrate the material; therefore, transported seawater or water from any local and sustainable watercourse can also be used without compromising the structural rigidity.

Within 24 hours, the material reaches 80 percent strength and the shelters are fully operational and ready to use. The inflated inner now functions and as a sealed and sterile environment which can vastly increase the frontline medical capabilities of the shelters in disaster areas or war zones.

On the outside, the fully hardened concrete shell has several key benefits which make the shelter ideal for use in a number of challenging situations. Firstly, since the structure is fully self-supported, it can be covered in materials such as snow, sand or earth to enhance its thermal performance. Secondly, the outer layer of concrete fabric is fireproof due to being a ceramic. It also provides protection against small arms fire and shell fragments, making it ideal for medical operations in combat areas. These features are simply unattainable with traditional soft skin structures and fabrics. Furthermore, the lockable doors provide an added level of security not possible with conventional tents.

Concrete Canvas co-founder Peter Brewin also highlighted another advantage to the structures compared to traditional alternatives.

“Because it’s a hardened building just as you would in any conventional permanent building, you can drill holes, attach fixings and install services in exactly the same way,” he said.

As such services such as electricity can be installed, again increasing the capabilities of the shelter.

In developing the Shelter, Brewin and Crawford realised the potential of the Concrete Canvas fabric itself, and moved into commercial production of bulk rolls of the material in three thicknesses: 5mm (CC5TM), 8mm (CC8TM) and 13mm (CC13TM). The success of the material led to the development of a sister product: CC HydroTM (CCH) for containment applications. Both materials have been used in a large variety of projects around the world from slope protection to channel lining and secondary containment. Concrete Canvas Ltd is now a multi-million-pound company and is growing year on year, with around 80-90% of all material produced being exported worldwide.

Concrete Canvas, however, have continued to be able to help those in difficult situations with their products. Co-founder Will Crawford said, “Recently (CC has been used) in developing countries to help reduce water loss in water transportation canals, which is increasingly becoming an area of global interest. Limiting water loss and looking after our water resources is increasingly important.”

However, getting the product specified for projects isn’t always easy.

“The product is used generally for civil engineering applications,”Crawford said. “The biggest challenge is convincing what is traditionally a very conservative market – engineers and the construction sector – to use a completely new material. It’s about communicating first of all that this new product exists, and then persuading them that the benefits are worth them taking the risk to use the new material and that has been incredibly difficult, particularly in the market segment we are targeting.

Concrete Canvas Ltd. are currently on track to achieve another best ever year for sales, and hope to continue to grow in the coming years as a result of a growing client base, increasing export demand, and a brand-new manufacturing facility and HQ to support this demand.

Thomas Goodall is a graduate of Newcastle University who writes about a variety of topics, including technology and sustainability, and contributes work to a range of online publications.