A new carbon-negative aggregate is being trialled on a stretch of motorway as part of National Highways’ hunt for new and innovative solutions to help reduce its carbon footprint.

The construction material was identified in a competition run by National Highways which offered funding for projects that would help meet targets for net zero carbon in maintenance and construction.

Four firms received up to £80,000 each to make their vision a reality and now the first of those – Seaham-based company Low Carbon Materials - has been able to trial its ACLA carbon-negative aggregate on a National Highways’ road for the first time.

With the support of both Skanska and Tarmac, the trial is taking place on the northbound carriageway of the M11 in Essex and has been incorporated into essential resurfacing and maintenance work between junctions 7 and 8. 

Here it will be subject to ‘real world’ levels of heavy traffic and will have routine monitoring by National Highways.

A test strip of asphalt concrete binder course containing LCM’s product has been laid alongside a control test strip containing 100% conventional aggregate. 

It is hoped the carbon-negative aggregate will make a significant impact on National Highways carbon emissions with minimal change to standard procedures.

Joanna White, National Highways’ research, development and innovation director, said:  “Solutions like this could have a real impact on our road to net zero carbon so we are delighted that we have been able to accelerate the development of the product and get it on one of our roads for testing.

“Collaboration is the key to innovation so we are grateful for the support of our supply chain partners Skanska and Tarmac who have helped make that happen.

“Testing the asphalt in real conditions on a heavily trafficked motorway, under close scrutiny, will be far more effective in proving the durability of the product and hopefully its success.”

National Highways launched the Accelerating Low Carbon Innovation competition, in collaboration with Connected Places Catapult, last year.

It is the latest competition funded through Designated Funds, ring-fenced funding used to invest in and support initiatives that deliver lasting benefits for road users, the environment and communities across England. 

An innovation showcase was held at The Barbican in London in June which highlighted seven trials of technologies and products that have been carried out in the past 18 months thanks to competitions organised through the Innovation and Modernisation Designated Fund. 

The event included a panel discussion with members of the supply chain that highlighted barriers to innovations deployment and advice on how to overcome these barriers.

The other three firms that made it through to the final stage of the Accelerating Low Carbon Innovation programme and are continuing to develop their projects are:

• PRG (Scotland) Limited, Hamilton – to produce a bitumen-like substance from waste tyres which would be useful for road construction and repairs.
• Circular11 Ltd, Christchurch, Dorset - to provide highly durable, maintenance-free fencing material that turns mixed low-grade plastic into low-carbon infrastructure, and which will be collected and recycled at end-of-life.
• Asset International Structures, Cwmbran  - to develop smart fibre reinforced polymer bridge beams that incorporate a novel optical fibre, enabling structural performance monitoring in real time and over long term.

Low Carbon Materials chief executive officer, Natasha Boulding, said: "We are excited by National Highways' recognition of the potential of our carbon-negative aggregate.

“A motorway trial represents a significant step towards lower carbon roads and widespread adoption. ACLA offers a simple and scalable solution that can be readily adopted by National Highways in their pursuit of their net zero targets."