What goes around comes around

Researchers at the University of Cambridge have developed a method to produce very low-emission concrete at scale.

The method uses the electrically powered arc furnaces used for steel recycling to simultaneously recycle cement, something the engineering researchers call “an absolute miracle”.

They found that used cement is an effective substitute for lime-dolomite flux which is used in steel recycling to remove impurities and ends up as slag. Recovered cement paste can be reclinkered if used as a partial substitute for the lime-dolomite flux and the resulting slag can meet existing specifications for Portland clinker. It can be blended effectively with calcined clay and limestone, however, the process is sensitive to the silica content of the paste and silica and alumina that may come from the scrap, but this can easily be adjusted.

What’s more, the method does not add any significant costs to concrete or steel production but reduces emissions from both concrete and steel.

Tests by the Materials Processing Institute showed that recycled cement can be produced at scale in an electric arc furnace and eventually the method could produce zero emission cement if the furnace is powered by renewable energy.

The engineering team has reported their findings in the journal Nature.

About the author

Desi Corbett

Desi is the Editor of Concrete in Australia and at the helm of our magazine for 8 years. She was behind the Institute's weekly news bulletins from 2016-2021 and is now writing our focused news items. Desi has been an engineering news and features journalist/editor across all disciplines since 2013 - part of a 30-year career writing for a wide range of industries.