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Pioneering Low Carbon Concrete Rings

Marshalls chamber rings stacked up in the yard

Blog

Pioneering Low Carbon Concrete Rings

23 Sept 25

3 min read

I’m Euan Mackinnon, Business Development Manager (North East England and Scotland) at Marshalls Civils & Drainage, and in this blog, I’m excited to share a behind-the-scenes look at a recent project we’ve been involved in, one that’s all about pushing boundaries in sustainable infrastructure – something we are passionate about at Marshalls.

Earlier this year, I had the opportunity to work closely with Scottish Water, Stirling University, and our long-standing partner Keyline Civils Specialists, who are the sole Framework supplier of precast drainage products on Scottish Water’s framework. Together, we explored a bold initiative to develop and trial low-carbon concrete manhole rings, with support from our internal technical teams and Recycl8, a leading innovator in low-carbon concrete.

The blog below outlines our journey through the Innovate UK funding competition, the collaborative effort to design and test new materials, and the exciting results from our full-scale trials using Recycl8’s R8Mix technology. It’s a story of innovation, partnership, and a shared commitment to building a more sustainable future.

A sustainable vision meets a real-world opportunity

When Keyline, our partner on the Scottish Water framework, approached us about supporting a low-carbon concrete initiative, we saw a valuable opportunity to contribute to this effort, aligned with our own sustainability goals.

The project was part of a funding competition led by Innovate UK, aimed at trialling alternative concrete mixes in infrastructure applications, specifically for us: chamber rings. The focus was on exploring materials beyond Ground Granulated Blast-Furnace Slag (GGBS) of which there’s a finite supply, to help reduce the carbon intensity of concrete and support wider industry efforts to adopt more sustainable construction methods.

Collaboration at its best

I had the pleasure of joining an initial meeting with Scottish Water, Stirling University and Keyline Civils Specialists to understand the scope of the opportunity. From there, our technical teams led by Nick Jowett, Marshalls Technical Director, sprang into action – designing trial concepts, preparing costings, and investing time and expertise into the bid.

Although our submission wasn’t successful for the £500,000 prize fund, the value of the work we’d done was clear. Scottish Water saw the potential and agreed to proceed with trials anyway, partnering with Recycl8 to test their R8Mix low-carbon concrete additive.

What is R8Mix?

Recylc8’s R8Mix is a game-changer. It’s made by repurposing incinerator bottom ash aggregate (IBAA), a by-product from energy-from-waste facilities that would otherwise end up in landfill. Using R8Mix as a replacement for virgin aggregates, we’re reducing carbon emissions and supporting circular economy principles, which aligns perfectly with Marshalls’ own targets.

Full-scale trials: From concept to reality

We kicked off full-scale trials using our 1200mm chamber rings, manufactured with R8Mix. The results? Extremely promising. All units passed strength performance testing, and we’ve retained additional rings for further inspection and viewing as required by Scottish Water.

Next steps include more detailed performance testing, including leachate analysis, to ensure the rings meet all necessary standards for long-term use.

Industry recognition

Recycl8 shared their excitement on LinkedIn, highlighting the successful production run and encouraging performance data. Their post captured the spirit of the project perfectly.

Circular, innovative solutions like R8Mix can meet the demands of real-world infrastructure.

Recycl8

Driving innovation in sustainable infrastructure

This project is a testament to what can be achieved when industry leaders come together with a shared vision. At Marshalls Civils & Drainage, we’re proud to be part of the Low Carbon Concrete Collective and to support trials that could reshape how infrastructure is built in the UK.

We’re committed to achieving zero waste to landfill by 2030, and initiatives like this help us move closer to that goal. By working with our sites, suppliers, and customers, we’re identifying and implementing circular economy strategies that make a real difference.

A big thank you

A huge thank you to Scottish Water, Keyline Civils Specialists, Stirling University, and Recycl8 for partnering with us on this important initiative. Your collaboration and commitment have been invaluable.

Together, we’re helping shape a more sustainable future for the industry – and we’re just getting started.