‘Carbon neutral’ brick developed by Carmody Groarke and Seratech team

Following an 18-month research period working alongside structural engineer AKT II and materials specialist Local Works Studio, start-up Seratech confirmed it is now also collaborating with Carmody Groarke to turn its brick concept into‘a commercially viable product’.

Unlike conventional clay bricks, which require firing at upwards of 1,200°C (and contain close to 1kg of embodied carbon per brick), Seratech’s brick is baked at 60°C overnight, then left at an ambient temperature for up to two weeks to reach optimum strength.

The brick uses a magnesium carbonate binder (‘the star of the show’), produced via Seratech’s proprietary carbon capture process, which allows carbon emissions from industry flues to be permanently stored within the built environment.

Research for the prototype was funded by the Engineering and Physical Sciences Research Council (EPSRC) and Higher Education Innovation Fund (HEIF). The design team has now been awarded a Design Exchange Partnership grant from the Arts and Humanities Research Council (AHRC).

The design team said that to maximise the research’s potential impact, architecture and its ‘associated regulatory frameworks’ would need to ‘adapt to accommodate the use of novel, low carbon materials through more robust detailing, [so that] the durability of the material becomes less critical than the way it is put together’.

Seratech’s technical director, Caitlin Howe, said the product would ‘hopefully make a difference to carbon emissions in the long run’.

She added: ‘Knowing there is scope for this product to change the entire industry is incredibly exciting and spurs you on. It really looks and feels like a conventional brick.’

Carmody Groarke sustainability lead Sian Ricketts said the practice was ‘really excited’ to be working alongside ‘material scientists who are operating at the top of their game and foster this collaborative process’.

Seratech was founded in 2021 by Imperial College London material scientists Sam Draper and Barney Shanks. Last year the pair landed the €100,000 2022 Obel Award with a groundbreaking method of creating carbon-neutral concrete from industrial production processes.

The company specialises in the research and development of carbon capture mineralisation and utilisation (CCMU) in construction to replace high-volume building materials, and has so far been awarded £1.8 million in grant funding.

Independently of this latest project, Carmody Groake previously collaborated with a team of material specialists and designers at the Design Museum Gent, in Belgium, to develop a different low-carbon brick prototype made from recycled municipal waste streams.

The brick was used on the façade of the new museum wing in September 2022.

Just how sustainable is it?

A sustainability expert accesses Seratech’s brick 

How is the brick carbon neutral, as opposed to just low carbon?
The brick uses a magnesium carbonate binder, which is a secondary product of Seratech’s carbon capture, mineralisation and utilisation (CCMU) process. This binder is carbon neutral and could in the future be carbon negative if it is produced with atmospheric CO2 rather than from industrial flues.

The prototype incorporates aggregates made from recycled industrial waste and cured at a low temperature (60°C) overnight. However, this can be eradicated in the future through electrification using wholly renewable energy. The prototype bricks will undergo a life cycle assessment to accurately understand the environmental impact.

Where do the raw materials come from, and what is the nature of the extraction process?
The magnesium carbonate binder is produced from olivine – a globally abundant and well-distributed mineral with large deposits for extraction in Norway, Oman, New Zealand and the US. Its abundance is due to its stability at high temperatures and pressures.

The aggregate for the brick has been primarily sourced from construction waste streams readily available in south-east England, and is representative of wastes typically available all over the world.

Can this prototype be upscaled quickly and affordably?
The current prototype is still in development, and will undergo a comprehensive testing regime over the coming months to verify its performance against design standards. Once this is complete, production could conceivably be upscaled quickly since it uses existing processing equipment at brick plants. The affordability of magnesium carbonate and low-energy process means these bricks should be price competitive with existing clay bricks.

We hope the outcomes of the research will provide a viable model for the wider use of magnesium carbonate in building materials to reduce carbon in construction and strengthen existing research into novel building materials and the circular economy.

Unfired bricks have been around for a while, though lacked robustness. Why do these bricks have to be fired at all?
Unfired bricks, such as rammed Earth products, are as old as humanity. But they lack durability because they harden by drying and this process can easily be reversed when they come into contact with water.

As a result, they are often deemed unsuitable for exposed external applications. Fired clay bricks, on the other hand, go through a permanent chemical change when fired. Similar to clay bricks, magnesium carbonate bricks set through a phase transition, but only 60°C is required to activate this, rather than over 1,200°C required by clay bricks.