Man looks at baking tin, makes brick - vegetable oil binder

Clay Technology magazine
,
8 Oct 2012

Inspiration can strike in the strangest of places. Such as a crusty baking tin. Dr Salah Zoorob, from the Department of Civil Engineering at the University of Leeds, UK, came home one night chewing over the problem of finding a binder that could be used to turn waste material into bricks.    

‘He looked at his baking tins and saw the black stuff ,’ says Mark Nichols, CEO of Encos Ltd, based in Leeds, UK. ‘It was a seminal moment. Zoorob realised that it was a biopolymer from the vegetable oil, caused by the reformation of triglycerides by the application of heat.’ And, as any amateur baker knows, it is almost impossible to get off. Nichols likens the effect of the biopolymer to the way linseed oil is used to harden paint, with the exception that heat is required. ‘It’s the same chemical reaction except you catalyse it with a bit of heat, which in this case was gas mark 4.5.’    

‘This invention is 20,000 years old,’ Nichols adds, pointing out that the same chemical is seen in the palaeolithic cave paintings at Lascaux in France, which are bound with heated vegetable oil. ‘That paint is still bound by the reformation of the triglyceride. This is basically an extension of that thinking into a product area that has never been exploited.’    

Encos is now manufacturing carbon neutral bricks based on the research, and with the support of a venture capitalist group, has been able to refine it into a proprietary binder called Encosol. ‘It’s a fairly magical substance,’ says Nichols. ‘It can bind any aggregate, and not only can it bind it, but we know how to engineer the particle distributions in it. As long as we have engineered the profile [of the aggregate] appropriately, it will fully encapsulate the material. This means that nothing will leak or seep out.’    

The binder is also highly versatile when it comes to the aggregates it can work with, says Nichols. ‘Limestone fines are our aggregate of choice, but we’ve looked at rice husk ash, cement kiln dust, pulverised fuel ash and incinerated sewage sludge ash. You name it, we’ve probably had a go at it.’ The combination of a biopolymer binder and waste aggregate (containing enough moisture for the production process) equates to a carbon neutral brick that doesn’t consume or produce water, according to Nichols. ‘We have no concerns about recyclability. In terms of this becoming part of construction demolition waste, unlike cement-bound products, you could rebind our products either with our bind or with cement.’    

After a successful series of scale trials, the company claims to have achieved a production rate of 36 Encosbricks every 12 seconds, using either a block machine or extrusion. ‘During our curing process our products don’t change dimensions at all. We can make brick slips between 10–30ml thick at very low cost,’ says Nichols. ‘That contrasts with the brick slips that are made today by cutting the face off a brick. If we think about the green deal about to fall upon us, we can manufacture slips inexpensively, sustainably and to very precise dimensions.’    

Nichols thinks that the development of the Encosbrick has a lot to do with supplementing the technical expertise of a brick manufacturer with the freewheeling creativity of university researchers. ‘You’ve got people who are given the time and space to exercise more lateral thinking because they aren’t focused on getting the product out of the door tomorrow, they are focused on discovery and keeping an open mind. Some people say luck befalls the prepared mind – Zoorob certainly had a prepared mind and happened to see something on his baking tin that nobody had seen for 20,000 years.’