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Using cold recycling technology developed in-house, Aggregate Industries has taken a major step in the direction of more sustainable pavements.
In the north-west of England, close to the border with Scotland, the A590 trunk road is an important link between the southern and northern parts of the county of Cumbria. Many tourists pass this way as they head towards the Lake District National Park.
In autumn 2020, a major improvement project was completed on this heavily used road. The existing pavement was in a bad way, with uneven surfaces and potholes posing a safety risk to drivers. The national road authority Highways England’s objective was to make sure that the job was completed with minimal disruption to the local road network.
The project, which was carried out by the construction company Aggregate Industries (AI) in collaboration with contractors A E Yates and Amey, included a totally new pavement on the section between the slip road to the M6 and the roundabout at the intersection with the motorway towards Brettargh Holt.
National Technical Manager Neil Leake explained that the ECI process (Early Contractor Involvement) was vital in making this scheme work. “Working collaboratively with all parties meant we could focus on the whole scheme’s carbon footprint; with each activity being tasked to reduce its footprint across the scheme. This drove a carbon culture from the very start and resulted in a carbon saving of over 40% compared to traditional methods.”
Through the ECI process, it was agreed that the top 320 mm of the existing pavement surface would be recycled back into the new pavement using AI’s ex-situ cold-recycled asphalt. AI also incorporated its new SuperLow asphalt to reduce further pavement carbon, making it possible to create a carbon-neutral pavement.
Steve Pointon, Operations Manager said: “To ensure continuous production of the foamed bitumen asphalt, FoamixTM*, a mixing plant was installed next to the workplace. This made it possible to quickly process, manufacture and deliver the new asphalt. This approach ensured maximum efficiency and meant that we could lay more than one thousand tonnes of asphalt per night, working 24 hours a day in two shifts, minimising disruption to traffic.”
In total, over 58,000 tonnes of material were extracted from the original pavement, of which almost 38,000 tonnes were recycled back into the new pavement, in just six weeks.
Apart from an improved circular economy and significant carbon reductions in the mixing process, this approach meant fewer transport journeys using heavy-goods vehicles (HGV) and reduced waste costs.
Nynas has also contributed to the successful project.
“We supplied two mobile storage tanks together with 730 tonnes of Nyfoam bitumen,” says Sarah Badley, Area Sales Manager North.
In view of the speed at which work proceeded, it was absolutely crucial that deliveries were made on an ongoing basis, so that the contractor had sufficient products in accordance with the schedule.
“Levels of activity and productivity were also extremely high, so the collaboration between the different actors was a key factor in both the positioning of the tanks and the bitumen deliveries,” adds Sarah.
It is now hoped that the industry can work even more closely together and jointly make use of the expanding range of environmentally adapted products and services.
Paddy Murphy, AI National Contracting Director, said “This is an important step in making a real difference on future infrastructure projects, contributing to sustainable development and reducing the industry’s carbon footprint.”
*FoamixTM was developed by Aggregate Industries. It is an asphalt with carefully combined ingredients that are bound together by a “foam” of bitumen and water.