Cocoon Carbon wins £11m to turn electric-arc furnace slag into cement replacement
This article covers Cocoon Carbon, a materials startup, which has raised £11m in a series A funding round led by 2150 and Brick & Mortar Ventures, with participation from TVC (The Venture Collective). The funding will finance deployment of its first commercial demonstration facility in the United States, accelerate hiring across the US and the UK, and aims to expand a supply route for supplementary cementitious materials used by concrete producers.
Cocoon Carbon, a materials startup, has raised £11 million in a series A funding round led by 2150 and Brick & Mortar Ventures, with participation from TVC (The Venture Collective). The financing will fund deployment of the company’s first commercial demonstration facility in the United States and accelerate hiring across the US and the UK, aiming to expand a new supply route for supplementary cementitious materials used in concrete.
Why it matters
The announcement addresses a narrowing supply of supplementary cementitious materials, or SCMs, used by concrete producers to lower carbon intensity and stabilise costs. Historically sourced from coal plants and iron blast furnaces, SCM supply is tightening as those facilities are retired across the US and Europe, while global infrastructure demand is projected to double over the next 40 years. Market indicators cited by Cocoon suggest SCM demand is growing at roughly 6–7% a year and prices in several markets have doubled since 2017.
Cocoon’s approach could unlock a large, local feedstock from electric arc furnace steelmaking, which industry forecasts expect to expand markedly by mid century. If the material performs at scale, it could help concrete producers access lower-carbon, more affordable inputs without rebuilding supply chains.
Inside the product
Cocoon Carbon converts steel slag, a byproduct of electric arc furnaces, into a cement replacement by capturing molten slag and cooling it rapidly. The company says its rapid cooling technology can be retrofitted into existing electric arc furnace waste handling lines and cools slag around 100 times faster than incumbent techniques. The output is an SCM that the company says matches the performance of traditional SCMs and can be used as a drop-in replacement in concrete formulations, potentially reducing embodied CO2 of concrete by up to 40%.
Rather than building standalone plants, Cocoon integrates production at steel mills, aiming to reduce energy inputs, capital expenditure and transport costs. Tens of millions of tonnes of steel slag are produced annually in the US and Europe, offering a material base that the company plans to convert into a distributed supply across steel plants.
Who are the investors?
The round was led by 2150 and Brick & Mortar Ventures, with participation from TVC (The Venture Collective). The funding will be used to build and validate Cocoon’s first commercial demonstration facility in the US, scale up operations and hire process engineers, materials scientists and commercial staff in the UK alongside plant operators and technical staff in the US.
Jacob Bro, Partner at 2150, said:
Concrete is one of the biggest value streams on the planet, providing the foundation of our civilization, from buildings to infrastructure to data centers. It consumes orders of magnitude more energy than AI and emits more CO2 than any other sector. Cocoon stands out in the innovation landscape with a product that is better and cheaper than cement and delivers a true drop-in replacement product for the industry.
Investors’ rationale appears focused on validating performance at industrial scale, establishing an operating track record and enabling rollout across more than 50 steel plants in the US and Europe. Third-party validation and a prior pilot at a major steel mill were presented by the company as de-risking milestones ahead of commercial deployment.
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Founder perspective
Eliot Brooks, Co-founder and CEO at Cocoon Carbon, framed the funding against market dynamics and the company’s deployment strategy.
Eliot Brooks, Co-founder & CEO at Cocoon Carbon, said:
The SCM market is facing a structural deficit at exactly the moment infrastructure demand is rising. We’re focused on delivering a plug-and-play solution that gives concrete producers access to affordable, local materials - while improving the economics of electric steelmaking. Expanding supply is the fastest way to stabilize costs and lower carbon in concrete.
Over the past year the startup has piloted its technology at a major steel mill, completed third-party validation of the material in concrete applications, and opened an R&D facility and concrete testing lab in London.
The bigger picture
Cocoon’s model sits at the intersection of industrial decarbonisation and circular materials use: turning a steelmaking byproduct into a lower-carbon component for concrete. If the US demonstration plant validates lab and pilot results, the approach could relieve pressure on SCM supply chains that have tightened as legacy industrial sources are retired.
The deal also reflects investor interest in industrial materials solutions that can be integrated into existing operations rather than replacing them entirely, a model that can reduce upfront capital needs and speed adoption.
This funding round is part of a broader trend of investment into industrial decarbonisation and materials innovation across the UK, Europe and the US. Cocoon’s plans to scale across steel plants on both sides of the Atlantic will test how quickly industrial partners and concrete producers can convert pilot technologies into routine, lower-carbon inputs for large infrastructure programmes.
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