Home » World’s first industrial net zero cement trial kicks off

World’s first industrial net zero cement trial kicks off

by Sion Geschwindt

Decarbonising cement production is one of construction’s great conundrums. This trial looks to change that…

Cement production is one of the biggest contributors to global carbon emissions, but also one of the most difficult industries to decarbonise.

While there have been many attempts to produce greener cement mixtures, it has not been possible to make the reactive component of cement without emissions – until now.

A UK-based pilot project aimed at producing the world’s first zero-emissions cement on an industrial scale was officially launched this week.

The first melt carried out by the Materials Processing Institute

Through a two-year trial, Cement 2 Zero will investigate both the technical and commercial aspects of upscaling Cambridge Electric Cement (CEC).

CEC, which was invented by three researchers at the University of Cambridge, is produced by converting construction and demolition waste to cement over molten steel, using an Electric Arc Furnace (EAF), which is used to recycle scrap steel.

The two-year industrial trial will test each stage of the production process and brings together the expertise of the Materials Processing Institute, the University of Cambridge and key supply chain partners – Atkins, Balfour Beatty, CELSA, Day Aggregates and Tarmac.

The first phase of trial melts is currently being carried out by the Materials Processing Institute.

Once the process has been substantially trialled, developed and de-risked effectively, industrial scale melts will follow at steel manufacturer CELSA’s furnace in Cardiff.

From here the partners look to produce 20 tonnes of CEC to be used on a live construction site.

If successful, it could not only further the decarbonisation of the hard-to-abate cement, steel and construction industries, but influence how we recycle, construct and maintain our built environment and infrastructure.

The science behind it

The Cambridge Electric Cement process begins with concrete waste from demolition of old buildings. This is crushed, to separate the stones and sand that form concrete from the mixture of cement powder and water that bind them together. The old cement powder is then used instead of lime-flux in steel recycling.

As the steel melts, the flux forms a slag that floats on the liquid steel, to protect it from oxygen in the air. After the recycled steel is tapped off, the liquid slag is cooled rapidly in air, and ground up into a powder which is virtually identical to the clinker which is the basis of new Portland cement.

Traditional Portland clinker, one of the main ingredients in cement, is produced by firing limestone and other minerals in a kiln at extremely high temperatures (1,450 degrees Celsius), a process which accounts for more than 50% of the cement sectors’ emissions.

By contrast, Cement 2 Zero will use recycled cement as the flux in the electric steel recycling process, with the EAF powered by renewable energy. The by-product of which, when cooled and ground, is then blended to make ‘zero-emissions’ cement.

Dr Philippa Horton, University of Cambridge, who created the project consortium, said: “If Cambridge Electric Cement lives up to the promise it has shown in early laboratory trials, when combined with other innovative technologies, it could be a pivotal point in the journey to a zero-emissions society.

“The Cement 2 Zero project is an invaluable opportunity to collaborate across the entire construction supply chain, to expand CEC from the laboratory to its first commercial application.”

CEC could be made in a virtuous recycling loop, that not only eliminates the significant emissions of cement and steel production, but also saves raw materials, as illustrated in the infographic above.

Professor Julian Allwood, University of Cambridge and Cambridge Electric Cement, explained: “By combining steel and cement recycling in a single process powered by renewable electricity, we could supplement the global supply of the basic construction materials to support the infrastructure of a zero emissions world and to enable economic development where it is most needed.”

Read next: Recycled clay could cut cement emissions ’20-40%’

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