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. In pilot-scale trials of the new process, the Cambridge team have demonstrated this combined recycling process, and the results show that it has the chemical composition of a clinker made with today’s process.
Invention of the cement has been rewarded with a new research grant of £1.7m from EPSRC, to allow the Dr Cyrille Dunant, University of Cambridge, 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.