IN Brief:
- Heidelberg Materials resurfaced 1.5 miles of the A689 using 1,150 tonnes of CarbonLock asphalt.
- An Ammann eABG 4820 electric paver was used to lay the material, which contains biogenic carbon within its binder.
- Heidelberg reports a 21% carbon reduction against conventional hot-mix surfacing, with the council planning further performance monitoring.
Heidelberg Materials UK has completed a 1.5-mile resurfacing scheme on the A689 in Cumbria using its CarbonLock biogenic asphalt and an electric paving machine. The work, delivered for Westmorland and Furness Council between Harbut Lodge and the Alston War Memorial, combined a modified asphalt binder with alternative construction equipment under the authority’s existing highway maintenance framework.
The scheme used 1,150 tonnes of asphalt produced at Heidelberg Materials’ Keepershield plant near Hexham. The material was laid using an Ammann eABG 4820 electric paver, with the company reporting a 21% reduction in carbon emissions compared with conventional hot-mix asphalt surfacing. The works were completed within the planned programme, allowing subsequent highway activities to proceed.
CarbonLock contains biogenic material incorporated into the asphalt binder. Heidelberg Materials says this material absorbs carbon dioxide from the atmosphere during its lifecycle and retains the carbon within the asphalt, including when the pavement material is subsequently recycled. The environmental characteristics of the binder form part of the company’s approach to lowering the carbon footprint of road construction.
The binder remains an essential component of the asphalt mixture, coating and connecting the mineral aggregate particles that form the pavement structure. Its properties influence how the material behaves during manufacturing, laying and service. The incorporation of biogenic material must therefore be considered alongside the mixture’s mechanical and durability requirements, with the completed surface expected to perform under the traffic and environmental conditions of the A689.
Asphalt performance depends on the combination of aggregate grading, binder characteristics, production conditions and compaction. The distribution of aggregate sizes affects the internal structure of the mixture, while the binder contributes to its cohesion and response to loading. The finished pavement must also provide a suitable surface for road users and resist deterioration during repeated traffic movements and changing weather conditions.
Heidelberg Materials’ use of CarbonLock on the A689 provides an installed example of the biogenic formulation within an established local-authority resurfacing programme. It was the first application of the product under the company’s highway framework agreement with Westmorland and Furness Council, which was awarded in 2024.
The material was manufactured at Keepershield before being transported to the site for laying. The production and delivery sequence had to be coordinated with traffic management and the planned paving operations, ensuring that the asphalt reached the construction area under suitable conditions for placement and compaction. Maintaining that sequence is particularly important when surfacing work takes place within restricted road access periods.
For the laying operation, Heidelberg Materials used the Ammann eABG 4820, a battery-electric asphalt paver intended for substantial road construction work. Ammann specifies that the machine can lay up to 1,200 tonnes of asphalt on a single charge under suitable conditions. That rated capability exceeds the total asphalt quantity used on the Cumbria scheme, although actual operating range depends on the equipment’s workload and site conditions.
Electric propulsion changes the energy supply for the paving operation. A conventional paver relies on an onboard combustion engine, while the electric machine draws energy from its battery. Removing diesel combustion from the paver itself reduces exhaust emissions at the point of operation and changes the equipment’s noise and maintenance characteristics.
Battery capacity and charging arrangements must be matched to the paving programme. The machine’s energy consumption depends on operating time, the demands placed on its drive and material-handling systems, and the working conditions encountered during laying. Where a surfacing programme requires extended operation, the contractor must account for the available charge and opportunities to replenish the battery without disrupting asphalt deliveries.
Those considerations link the electric equipment directly to the construction sequence. Resurfacing work requires preparation of the existing road, delivery of asphalt, paving, compaction and the completion of associated operations before traffic can return. A change in paving equipment must be accommodated within that sequence, particularly where a local authority has agreed a defined window for completing the works.
Heidelberg Materials and Westmorland and Furness Council developed the scheme jointly, seeking to incorporate lower-carbon materials and electric equipment without extending the resurfacing programme. The contractor completed the work on time, demonstrating that the selected equipment and material could be incorporated into this particular highway maintenance operation.
Adrian Stubbs, regional general manager at Heidelberg Materials Contracting, said: “We worked to a tight schedule and delivered the improvement works on time, ensuring further planned work was not impacted.”
The reported carbon reduction is based on Heidelberg Materials’ comparison with laying standard hot-mix asphalt. The published project information combines the use of CarbonLock and electric paving equipment, but does not allocate the overall saving between the binder formulation, the paver and other construction activities. The figure should therefore be treated as the company’s reported outcome for the resurfacing comparison.
The carbon retained within the biogenic binder is also relevant to the future handling of the pavement. Heidelberg Materials says the captured carbon remains stored when CarbonLock asphalt is recycled, potentially allowing recovered pavement material to retain that characteristic through subsequent processing and reuse. The future recovery arrangement will depend on maintenance decisions and the methods used when the road surface eventually requires replacement.
Westmorland and Furness Council intends to monitor the completed section and evaluate its performance before considering further opportunities for similar construction methods. The road’s response to traffic and weather will provide practical evidence alongside the initial construction results, allowing the authority to assess the material within its maintenance programme.
Kieron Tetchner, lead network manager at the council, identified continued monitoring and evaluation as part of its approach to the scheme. The work was developed through collaboration between council highways staff and Heidelberg Materials engineers, who assessed where the alternative asphalt and electric equipment could be incorporated into the planned resurfacing operation.
The A689 trial has delivered a completed road surface using a biogenic asphalt formulation and a battery-electric paver within an existing highways contract. Its construction programme and reported carbon performance provide an initial reference for further projects, while the council’s monitoring will establish how the installed material performs in service.
