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World’s first zero-emissions cement developed in Cambridge

The world’s first zero-emissions cement has been invented by three engineers in Cambridge.

Cement is a vital part of the construction process
Cement is a vital part of the construction process

Three Cambridge engineers, Dr Cyrille Dunant, Dr Pippa Horton and Professor Julian Allwood, have filed a patent and been awarded new research funding for their invention.

Replacing cement is one of the hardest challenges on the zero-emissions roadmap. Reduced-emissions cement has been achievable – by mixing new reactive cement (clinker) with other supplementary materials – but it has not been possible to make the reactive component of cement without emissions.

The new cement is made in a virtuous recycling loop that eliminates the emissions of cement production, saves raw materials, and reduces the emissions needed to make lime-flux.

The inspiration for Cambridge Electric Cement struck inventor Dr Dunant when he noticed that the chemistry of used cement is virtually identical to that of the lime-flux used in conventional steel recycling processes. The new process begins with concrete waste from the demolition of old buildings. This is crushed, to separate the concrete (stones and sand) from the mixture that binds them (cement powder and water). 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 the new cement.

Cambridge Electric Cement uses an alternative process which is net-zero friendly
Cambridge Electric Cement uses an alternative process which is net-zero friendly

The Cambridge team has demonstrated the process in pilot-scale trials, and the results show all the properties of cement made by today’s conventional process.

The new cement was invented as part of the large multi-university UK FIRES programme led by Professor Allwood, which aims to enable a rapid transition to zero emissions based on using today’s technologies differently, rather than waiting for the new energy technologies of hydrogen and carbon storage. Invention of the cement has been rewarded with a new research grant of £1.7m from EPSRC, to allow the inventors to collaborate with Dr Zushu Li at Warwick University and Dr Rupert Myers at Imperial College, to reveal the underlying science behind the new process. The new grant will fund an additional team of researchers, to probe the range of concrete wastes that can be processed into Cambridge Electric Cement, evaluate how the process interacts with steel making, and confirm the performance of the resulting material.

Professor Allwood said: “If Cambridge Electric Cement lives up to the promise it has shown in early laboratory trials, it could be a turning point in the journey to a safe future climate.

“Combining steel and cement recycling in a single process powered by renewable electricity, this could secure the supply of the basic materials of construction to support the infrastructure of a zero emissions world and to enable economic development where it is most needed.”

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