Ureaka

This University of Strathclyde project is one of many startups racing to permanently lock co2 into the chemistry of concrete. But it thinks it has a unique proposition.

Locking away captured carbon dioxide within the chemical structure of concrete is a tantalising prospect. If this could be done at scale, it could help mitigate the costs associated with storing CO2in geological reservoirs. Because the bonds are permanent, the risk that it will escape back into the atmosphere is low.

Existing methods of storing CO2 within concrete are often based on passing the gas over variously treated elements, including crushed concrete that is being recycled. “It works, but it can be slow and running the gas chambers can be expensive,” says Philip Salter, founder of Ureaka, a prospective spinout company from the University of Strathclyde in Glasgow. “Our approach differs from most others in that it is based on a wet chemical process. It’s fast, has a high degree of circularity and you don’t need large inputs of energy or chemicals to make it work.”

Salter came up with the idea almost by accident, while studying for a PhD in bio-cementation, using carbonate precipitation to bind materials together. “One of the experiments was not behaving as expected,” he says. “There was no smell of ammonia, usually a very obvious sign that the reaction is taking place. That small observation sent me down a far bigger rabbit hole.”

He started looking more deeply at ammonia chemistry, volatile compounds and whether the by-products of these cementation reactions could be captured and reused rather than treated as waste. “Over time, the question shifted from ‘Why is this experiment not working?’ to ‘Could the whole chemistry be redesigned as a circular process?’”
Earlier this year, he pivoted again. Ureaka was originally set up to make bio-concrete from waste products and plant-derived enzymes.

But he realised that there was much greater potential to change the industry with a supplementary cementitious material (SCM). He is now in the process of testing mortar prisms in which Ureaka’s SCM replaces up to 30% of the cement. The initial feedstock is rejected concrete roof tiles, supplied by manufacturer Wienerberger. “They contain calcium, silica and alumina that can be recovered and turned into new construction materials,” says Salter.

The waste concrete is processed using a proprietary liquid. This separates the sand – which can be recovered – from the cementitious material. Captured CO2 is then rapidly mineralised in the solution to produce an activated cement replacement. The CO2 Salter is currently using is a waste product of whisky production, and is typically used to make dry ice and for other industrial applications. “It’s a clean, controlled source, which is helpful while developing and validating the process,” he says. “Longer term, the goal is to use CO2 captured on site at cement plants and mineralise it directly into SCMs.

That is where the technology becomes most strategically relevant.” He is quick to clarify that Ureaka would not be an alternative to carbon capture at cement plants. “Even with broader quarry, mining and industrial mineral residues, mineralisation won’t operate at the same scale as geological storage. But by converting even a fraction of captured CO2, we could produce tens of thousands of tonnes of material and significantly improve the economics of the wider carbon capture and storage system.”

The process has another advantage, he adds: a low-energy route to recover the chemical inputs, so they can be reused. “That circularity could be attractive both environmentally and economically as the technology scales.”
What about the concrete? Initial tests are encouraging, showing strength gain and compressive strength within the expected range for control mortar mixes made with Portland cement (CEM I). They have also begun testing against Portland-limestone cement mixes (CEM II), retaining around 90% of the 28-day compressive strength of the control at a 20% replacement level. “We are now building out the full dataset with more standardised testing and repeatability,” he says.

The team is preparing to supply a pilot batch to Wienerberger for testing under its roof-tile manufacturing and accelerated-curing conditions. External validation with other industry partners is also planned as production scales towards 25-30kg per batch. Ureaka is currently planning a pre-seed round of funding to support scale-up and commercial partnerships. It is also actively seeking partners across the supply chain, including waste concrete suppliers, mining and quarrying companies interested in fines upcycling, cement and concrete producers, and construction materials companies.

“The next phase is about converting the technical proof into repeatable pilot production and customer validation,” says Salter. “There is a lot of competition for funding in this area, and inevitably that will affect how soon we can bring our process to market. We are building the industry partnerships, team and production capability needed to move quickly.” 

Interview by Tony Whitehead

Photos Paul Burroughs

^{Published in CQ Summer 2026}