Gimme Shelters, The Inflatable Concrete That’s Spread Across the World
The material, effectively “concrete on a roll”, is the creation of engineers Peter Brewin and Will Crawford, who came up with the idea 10 years ago when they were students at the Royal College of Art in London.
Working on a project to build inflatable concrete buildings, they had been tasked with creating a new use for cement.
While experimenting with Modroc – a plaster-impregnated bandage used to help mend broken bones – they came up with the concept of making inflatable shelters that could be constructed very quickly for use in emergencies.
After leaving the RCA, the pair continued to work on the idea of shelters that could be dropped into disaster zones or areas of military conflict and swiftly assembled.
What developed was Concrete Canvas, a fabric that hardens when sprayed with water, creating a waterproof and fireproof concrete layer. It is sold in large rolls which can be manipulated into shape onto the ground, on slopes and on existing concrete.
When they first developed the material, the partners focused on the shelters, which are now sold in two sizes - 25 and 50 square metres. They arrive in a large wooden boxes, attached to an electric fan which inflates the structure until it can support itself. Then the water is applied and the structure is ready to use within 24 hours, complete with doors for access.
It was clear from the early days that the material would have applications other than in shelters, although they didn’t know then what they might be. Says Brewin: “All the way through from the first prototypes that we made at college, we thought ‘this material is going to have a load of other uses.’” The real challenge, he says, was getting the material to be consistent and to work reliably.
Sales of the shelters proved problematic. In the aid sector, there were political difficulties in erecting semi-permanent buildings in environments such as refugee camps when the authorities might not want to admit that the problem would last for more than six months. Coupled with this was the demand for immediate supplies for hundreds of units when an emergency struck, something that was difficult for a start-up company to supply.
Where the business blossomed was in selling rolls of the material, which could then be manipulated into shape on site. The first major order came from the Ministry of Defence for use as a covering for sandbag walls in Afghanistan. Next came an order for a Network Rail project. Using a conventional method – preparing the concrete offsite and then transporting it in slabs – would have taken three weeks, said Crawford, while their method took just eight hours.
As a result, the partners realised that supplying the civil construction industry would be a far quicker way to grow the business than shelters.
Now the material is widely used in construction and engineering projects around the world, from lining ditches to securing underwater pipelines.
Shelters account for only around 1% of the company’s £5m-a-year turnover but they remain the clearest illustration of what is possible with the material, according to Crawford.
“It’s a really good example of what you can do with a thin flexible sheet of Concrete Canvas,” he says.
Sold in three different thicknesses, the rolls are marketed on the low labour cost of putting them in place, as well as the relative ease of transport to areas such as mines. One roll of their mid-thickness material, which weighs 1.5 tonnes, is equivalent to two trucks full of conventional mixed concrete. Where they are not so cost-competitive is in countries where labour is cheaper and access to sites is easier, said Brewin.
Although the company has been around for 10 years, the product is still relatively new to the construction industry and one of the challenges is to make contractors aware that it is available. “It is through that we will find more applications,” says Crawford. “The closest competitors are conventional methods of concreting. Those are what we are replacing, either pouring it, spraying it or precasting it.”
Mining, civil infrastructure and the petrochemical industry are the company’s three main markets. For future growth the company is targetting business in relining and refurbishing existing concrete structures that have suffered from degradation and cracking.
“A huge amount of the concrete infrastructure in the world, particularly in the west, was built fairly quickly after the second world war and the type of concrete they used had a lifespan of about 50 years.... so there is a huge opportunity in extending the lifespan of existing concrete infrastructure,” says Brewin.
The Inflatable Shelter
Watching one of the concrete shelters being constructed is similar to seeing a giant bed being inflated, albeit one with a lifespan of some 50 years. The shelter arrives folded in a wooden crate and, once positioned, an electric fan is activated which inflates the plastic inner part until it can support itself. Water is then sprayed on and, 24 hours later, it is ready to use. The smaller product - 25 square metres - can be constructed by two people without any training in less than an hour.
Shane Hickey, The Guardian