Scientists build a green success with recycled cement

A breakthrough in recycling cement from demolished buildings could be a real game changer in the battle to stop climate change, says a Midlands green energy expert.

Ron Fox, of Noreus Ltd on the University of Keele Science and Innovation Park (www.noreus.co.uk), was commenting on the success by a team of Cambridge University scientists to help sidestep the planet-warming carbon emissions with a world first – “electric cement.”

Cement is what binds the sand and aggregate in concrete together and is the mostly widely used material on the planet after water.

But Ron said the problem is that cement is made by heating limestone up to 1600C in giant kilns powered by fossil fuels, plus the heat used to move the carbon dioxide from the limestone. The whole process is estimated to produce a tonne of carbon for every tonne of cement.

“To put that in context, if cement was a country, it would be the third biggest source of world emissions after China and the USA as it is responsible for 7.5 per cent of human-made carbon dioxide,” said Ron.

The breakthrough came when the researchers found a link between recycling steel and cement. When steel is recycled chemicals are added that float on the surface of the molten metal to prevent it reacting with the air and creating impurities. Slag is the byproduct generated during that process.

Now scientists have found that the composition of used cement is almost exactly the same as slag used in electric arc furnaces. The hope is that electric cement will be cheaper to manufacture by using what is essentially waste heat from the steel recycling process.

Experts have been trialling this process at a small-scale electric arc hub at the Materials Processing Institute in Middlesbrough.

The lead scientist, Cyrille Dunant said they had found the high temperatures in the furnace reactivated the old cement and because electric arc furnaces can be powered by renewable energy, so the entire cement making process is decarbonised.

Ron concluded: “It could mean the cement industry would release no greenhouse gases which would have a dramatic effect on reducing carbon emissions.”

For more details on recycling and green energy call Ron on 0845 474 6641 or go to www.noreus.co.uk

Caption: Cementing a better future with ‘electric cement’.