‘It is very exciting to make progress in this area, but there are still many challenges to overcome…’
Researchers from the University of Tokyo, Japan, have found a way to take waste concrete and captured carbon dioxide, and combine them using a novel process into a usable form of concrete called calcium carbonate concrete. It is hoped that in the coming years the carbon-neutral material can replace traditional concrete in some applications, and play a role in tackling climate change. The research has been published in Journal of Advanced Concrete Technology.
The work has been carried out by Professor Ippei Maruyama and Professor Takafumi Noguchi, both from the Department of Architecture at the University of Tokyo. The research was inspired by the way some aquatic organisms harden into fossils over time, the researchers investigated if the process that forms the hard calcium carbonate deposits from dead organic matter could be applied to concrete.
‘Our concept is to acquire calcium from discarded concrete…We combine this with carbon dioxide from industrial exhaust or even from the air. And we do this at much lower temperatures than those used to extract calcium from limestone at present,’ said Professor Maruyama.
While calcium carbonate is a very stable material, and the ability to recycle large quantities of material and waste is desirable, calcium carbonate concrete cannot replace conventional concrete just yet. It is not as strong as conventional concrete, though for some small construction projects this would not be a problem. To date only small blocks of a few centimetres in length have been made.
Professor Noguchi, who is also the manager of the Calcium Carbonate Circulation System for Construction project said; ‘It is very exciting to make progress in this area, but there are still many challenges to overcome. As well as increasing the strength and size limits of the calcium carbonate concrete, it would be even better if we could further reduce the energy use of the production process.’