Producing bricks from waste

Published Wednesday 28 September 11

Developing fully sustainable and carbon-negative construction materials is the goal at Encos Ltd, a University of Leeds spin-off company. The company's patented method for manufacturing carbon-negative masonry products from waste materials is the result of research carried out by Dr John Forth and his team in the School of Civil Engineering.

The process uses a combination of vegetable oil-based binders which are mixed with graded waste aggregates. The mixture is then shaped into bricks and blocks and cured using low temperature heat. During the curing process the oil undergoes a number of complex chemical reactions which transforms it from a viscous liquid into a solid binding matrix. Producing the products uses no water, and creates no waste.

Laboratory-produced samples have already passed crucial industry tests including fire, freeze-thaw and compressive strength. A third-party report produced by Best Foot Forward Ltd estimates that manufacture of the Encos masonry blocks and bricks would result in a reduction of 160% and 120% respectively in greenhouse gas emissions, compared to traditional clay bricks and concrete blocks.

A wide range of waste aggregates and binders can be used in the process. Encos recently commissioned a £200,000 demonstration manufacturing plant at Yorkshire Water's Knostrop site in Leeds and will shortly be commissioning the necessary tests required before it brings its first product - a brick made of Furnace Bottom Ash (FBA) and Pulverised Fuel Ash (PFA) aggregates - to market. Another focus of the company's activities, being carried out in collaboration with Yorkshire Water, is the use of Incinerated Sewage Sludge Ash (ISSA) as the aggregate. Encos is also investigating the use of other waste aggregates, including rice husk ash.

The process could significantly reduce the environmental impact of the construction industry and also greatly reduce the amount of waste going to landfill. "We've got a revolutionary product, we use very little energy in making our products and use a binder which actually stores CO2 as opposed to emitting it," says Encos chief executive, Mark Nichols. "Not only does every tonne of bricks we create prevent about the same weight of waste material going to landfill, it also prevents an equivalent amount of primary resource being used."

Encos is currently discussing its products with major suppliers, customers and architects to determine how Encos products can be used to improve sustainability in the construction industry. Meanwhile, companies such as Yorkshire Water are already enthusiastic about the potential waste management developments that the process provides:

"Partnering with Encos may allow us to beneficially utilise a waste stream formed when producing high quality drinking water and treating waste water on behalf of our customers, moving us toward towards our zero waste aspiration," notes Jon Brigg, Innovation Development Manager at Yorkshire Water.

Encos and their bricks were featured on ITV Calendar on Tuesday 27 September. To watch the clip visit ITV Calendar's website, the segment is approximately 90 seconds into the clip.

For further information
Paula Gould, University of Leeds press office: t: 0113 343 8059, e: p.a.gould@leeds.ac.uk