Putting CO2 on the Road

One of the biggest factors in road construction emissions is the choice of materials. Reducing these emissions requires innovation – one solution is carbonated recycled concrete aggregate (cRCA), created by enriching recycled concrete aggregates with CO₂ through accelerated mineralisation. These aggregates, which can be used to build roads or to produce fresh recycled building materials, offer a simple, permanent and cost-effective method of permanently storing CO₂.

Take two major UK highway project proposals, for example: the A66 Northern Trans-Pennine and the Lower Thames Crossing. If these projects incorporated carbonated recycled concrete, they could permanently store over 19,000t of CO₂. This figure is equivalent to the emissions from 4,750 flights between London and New York. The environmental impact would be immediate, tangible and scalable across future UK roadworks.

Recycled concrete already plays a crucial role in modern road construction, most widely used as the filler material in the base layers of roads. However, the production of concrete, even when later demolished and recycled for use in road bases, is a significant contributor to CO₂ emissions, accounting for up to 8% of global CO₂ emissions. Looking at the global construction sector as a whole, demolished concrete is also the world’s largest waste stream.

The technology and approach to permanently storing CO2 in demolished concrete is already taking place Europe. Neustark, based in Switzerland, is a leading provider in this rapidly growing field, having developed a solution to permanently store CO₂ in recycled mineral waste streams such as demolished concrete.

The company does so by capturing CO₂ from biogenic sources, like biogas plants, liquefying it and transporting it to storage sites, where it is permanently mineralised in recycled concrete aggregates. The CO₂ reacts with calcium-rich materials in demolition waste, forming stable carbonates that lock the carbon away permanently.

Neustark recently entered the UK market, with its first site now operational in Greenwich, London, through a strategic partnership with Aggregate Industries. In a year, this site has the capacity to remove the equivalent of the carbon sequestered by 50,000 fir trees in the same time frame. The UK offers a strong market for scaling carbon removal, but more focus is needed on integrating it into existing supply chains – road construction is the perfect place to start.

Beyond the environmental benefits, integrating cRCA into UK road construction could drive economic advantages as well. The demand for sustainable materials is growing rapidly, and, if the UK construction industry positioned itself as a frontrunner in this growing field, it would create new regional business opportunities, attract investment and generate new jobs.

The transition to net zero requires bold action across all sectors, and UK road construction must not be left behind. The good news is that solutions exist today. Neustark offers a proven technology that can be implemented immediately in the UK, reducing emissions while strengthening the circular economy.

Neustark is urging policymakers, industry leaders, and procurement officials in the UK to take decisive steps now as the government prepares for the next RIS3. Embedding sustainable materials into road construction projects should be a priority. The UK has an opportunity to lead the way in climate-centred roadbuilding, that delivers environmental, economic and social benefits for generations to come.

By Valentin Gutknecht, CEO and co-founder of neustark

Source: New Civil Engineer