Concrete for the common good

A low-cost carbon-neutral concrete which promises to be easy to scale has taken out the international Obel Award 2022 which recognises outstanding contributions to human development.

Two PhD students, Barney Shanks and Sam Draper (pictured right), from Imperial College London have created Seratech that replaces part of the cement mix with a type of silica derived from carbon dioxide captured from factory flues.

The technology can also be integrated into existing concrete production without any major shift in practice as the silica can be blended with Portland cement on-site, just like other supplementary cementitious materials.

While a maximum of 40% of the concrete mix can be replaced in this way, Seratech’s creators say more carbon is stored in the concrete than is emitted in its production, rendering it carbon neutral.

“Replacing all the Portland cement is currently the only way to achieve carbon-neutral concrete without resorting to CCS or offsetting, however, this approach has significant drawbacks.” Sam Draper told Dezeen.

“The raw materials for these binders, often termed ‘geopolymers’, are not available at the required scale to make any significant dent in current cement production and emissions.

“The most common is GGBS [Ground Granulated Blast-furnace Slag], a by-product of steel production, but it is already entirely utilised as a partial cement replacement material.”

Seratech Cement says the advantage of its process is that it is the most practical for the immediate future. The raw materials needed for the process – carbon dioxide from industry, and olivine, a magnesium iron silicate – are abundant around the world.

And looking to the future, if emissions are lowered to a point where supply is no longer abundant, Sam Draper said Seratech could use an affordable direct air capture technology to draw carbon dioxide from the atmosphere.

Draper said “humanity can’t afford to spend 20 to 50 years scaling the technology to give us sustainable materials. It needs to be now.”

The €100,000 Obel Award is an international prize for architecture that honours recent and outstanding contributions to human development worldwide. The Henrik Frode Obel Foundation says the award is offered as an incentive to architectural and other professionals to consider their obligations towards the common good.

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.