'It could be a turning point': Cambridge engineers claim zero carbon cement making breakthrough

University aimed at finding method of decarbonising the cement industry using technology engineers readily available today

An innovative new zero emissions process that uses renewable electricity to recycle steel and cement could overcome one of the “hardest challenges on the journey to a safe climate with zero emissions”, according to University of Cambridge developers behind the technology.

The three engineers – Dr Cyrille Dunant, Dr Pippa Horton and Professor Julian Allwood – have filed a patent and secured new research funding for ‘Cambridge Electric Cement’, which they claim is the world’s first emissions-free route to recycle Portland cement.

The global cement industry accounts for around eight per cent of total global greenhouse gas emissions, and is widely seen as a major decarbonisation challenge, as cement making is an energy-intensive process that typically relies on fossil fuels.

But while there are various means of making lower carbon cement – such as by mixing new reactive cement (clinker) with other supplementary materials – until now, it has not been possible to make the clinker without generating any emissions at all, according to the engineers .

However, using an electric arc furnace steel recycling process, they claim their innovation is capable of producing cement that generates zero emissions in the process, and all within the parameters of established industrial processes.

“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,” said Professor Allwood. “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.”

The process begins by utilizing concrete waste from demolished buildings and infrastructure, which is crushed to separate the stones and sand that form concrete from the mixture of cement powder and water that bind them together, according to the developers. The old cement powder is then used instead of lime-flux in steel recycling, and 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 rapidly cooled in air, and ground up into a powder which the engineers claim is virtually identical to the clinker which is the basis of new Portland cement, they said.

In pilot-scale trials of the new process, the Cambridge team claim to have demonstrated this combined recycling process, and that the results show that it has the chemical composition of a clinker made with today’s process.

The Engineering and Physical Sciences Research Council has awarded the team a research grant of £1.7m to further develop the underlying science behind the process. The new grant will also fund an additional set 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, the engineers said.

The new cement was invented as part of the large multi-university UK FIRES programme, 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.

It comes amid increasing investment in greener cement R&D. In April, global cement giant Cemex announced $6.5m investment in Carbon Upcycling Technologies, a Canadian start-up which claims its process can reduce emissions from cement making by up to 30 per cent.



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