A34 Southbound South Ilsley to Chieveley
Combining powerful carbon reduction solutions in highways maintenance
Project overview
Heidelberg Materials partnered with National Highways on the A34 Southbound project in South Ilsley, Oxfordshire, to significantly reduce carbon emissions during highways maintenance. Leveraging local knowledge, we identified the A34 as a prime opportunity to push the boundaries of recycling, carbon reduction, and circular construction methodologies. The A34 Southbound scheme required extensive resurfacing, and Heidelberg Materials seized this as an opportunity to integrate innovative low-carbon solutions into pavement construction. By meticulously planning the scheme, we sought to showcase the latest advancements in sustainable road construction through the application of a range of technologies which blended recycled materials, warm-mix asphalt, and biogenic asphalt.
Key highlights
- 50% Recycled Asphalt Pavement (RAP) in the binder course, and 30% RAP
in the surface course, reused from the same site, minimizing reliance on
virgin materials. - First use of biogenic asphalt (CarbonLock) with ERA 140 warm-mix
asphalt on the UK SRN, contributing to a 20% reduction in CO2 emissions. - Planings from the A34 were backhauled to our local recycling center
and reprocessed for relaying, reducing material transport distances and
emissions. - Warm-mix asphalt applied in compliance with Clause 942 standards,
further minimizing the carbon footprint.
Sustainable innovation in action
The crux of this project’s innovation lies in the combination of three key levers to reduce emissions in highways maintenance – high RAP content, warm-mix asphalt, and biogenic binder, offering a substantial reduction in CO2.
Circular solution with high RAP content
The project achieved a circular economy approach by using the planings from the A34 itself. Our technical team leveraged our knowledge of the high 60 PSV aggregate in the existing carriageway surface and designed bespoke asphalt mixes containing 50% RAP in the binder course and 30% RAP in the surface course, enabling a fully closed-loop recycling system. This minimised carbon emissions by 7kg per tonne of asphalt, while also reducing vehicle trips and virgin material consumption.
Warm mix asphalt
This project made use of our ERA 140 Warm-mix asphalt product which, by producing the asphalt at a lower temperature, reduces embodied carbon emissions from production by 15% compared to traditionally hot-mixed asphalt.
Introduction of CarbonLock biogenic asphalt
The A34 project saw the use of CarbonLock bio-asphalt, which incorporates biogenic bitumen derived from renewable sources. This asphalt has the capability to lock in up to 6 tonnes of CO2 per kilometer, offering an additional 20% reduction in CO2 emissions on the scheme. Moreover, biogenic asphalt’s durability ensures fewer maintenance interventions, contributing to further whole-life carbon savings.
Sustainable construction by design
By engaging National Highways in ECI discussions well in advance of the scheme, all options were discussed to maximise efficient outputs and opportunities for the Road User and local economy. By maximising weekend closures the works were delivered across four weekend closures over four months, delivering in excess of 12,000t of material, as opposed to 30 consecutive night shifts, saving significant amounts of carbon emissions by reducing vehicle movements across the network.
Environmental benefits and outcomes
The combined use of high RAP content and biogenic asphalt significantly reduced carbon emissions both during construction and across the project’s lifecycle. Through careful planning and the integration of sustainable practices, Heidelberg Materials delivered the following key benefits:
Reduced CO2 emissions
The combination of using a highly-recycled solution, incorporating both warm-mix asphalt and CarbonLock biogenic asphalt, resulted in an overall carbon saving of 35% compared to a hot-mix asphalt solution.
Reduced transport emissions
Material planings were backhauled to one of our local recycling facilities at Sutton Courtney, Oxfordshire, and processed into new asphalt, reducing vehicle trips and reliance on virgin materials.
Extended pavement lifespan
The high durability of CarbonLock asphalt ensures fewer future maintenance requirements, leading to ongoing carbon reductions throughout the road's lifecycle.
Lasting impact on the highways sector
This project has set a new standard in sustainable road construction, providing a blueprint for future low-carbon maintenance schemes. Heidelberg Materials’ innovative approach – made possible by Atkins and the National Highways SES team who assisted in the design of the solution, and enabled the various departures to be approved – demonstrates that high quantities of recycled planings can be effectively combined with new, durable materials like biogenic asphalt, proving the viability of circular economy solutions in large-scale infrastructure projects. The success of the A34 Southbound scheme highlights the potential for significant carbon savings within the highways sector and offers a tangible example of how sustainable innovation can align with industry best practices. By reducing emissions at both the manufacturing and operational stages, Heidelberg Materials is helping to accelerate the UK highways sector’s journey toward net-zero carbon.