Three Cambridge engineers have filed to patent the world’s first emissions-free cement recycling process.
“Until now, it has not been possible to make the reactive component of cement without emissions,” reports the University of Cambridge Department of Engineering. “The new invention achieves this for the first time within the parameters of established industrial processes.”
Cement is an essential component of construction everywhere, but it is also a significant source [pdf] of the greenhouse gas emissions propelling climate change. “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 Julian Allwood, one of the engineers behind the new process.
Cambridge’s Dr. Cyrille Durant conceived the process after he noticed that the chemistry of used cement is nearly identical to that of the lime-flux used to remove impurities while recycling steel. Concrete waste from demolished old buildings is crushed to separate out cement from the sand and stone with which it is mixed. The cement is then used instead of lime-flux in steel recycling, where it forms a slag that floats to the top of the melting steel. After the recycled steel is tapped off, the slag is cooled rapidly, then ground into a powder that is “virtually identical” to the ‘clinker’ or binder that is the basis of new Portland cement—the most common type of cement in use around the world.
“Combining steel and cement recycling in a single process powered by renewable electricity 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,” said Allwood.
The new process was invented as part of the UK FIRES programme, led by 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,” writes the Cambridge engineering department. The invention has been awarded a new research grant that will fund further development.