30.11.2021
 

The Project

Working with Kier Highways, Aggregate Industries created a low carbon pavement solution for the resurfacing of the A46 Warwick northbound carriageway, recycling the existing carriageway for an eco-friendly and cost-effective solution.

The Brief

Aggregate Industries (AI) was appointed by Kier Highways to support on their Area 9 project to resurface 3.5 miles of dual carriageway on the National Highways’ network - by recycling more than half of the materials from the old road back into the new one and cutting the carbon footprint by 23%. A stretch of the busy road had deteriorated to a condition that, following a number of temporary repairs to ensure safety, a full depth reconstruction was needed, digging down 380mm to replace the layers of road surface.

Much of the material in the lower levels contained tar, which is classed as carcinogenic and must be dealt with as hazardous waste and disposed of at a licenced waste processing facility. But tar-bound material can be safely recycled and encapsulated back into the pavement layers by crushing and re-mixing it.

The Solution

Thus, Kier Highways and AI devised a low carbon pavement solution by recycling the existing carriageway material and reducing the amount that would have to go to landfill. Some 17,432 tonnes of material were reused from the layers of road surface, as well as helping to make the A46 Warwick Bypass much smoother and safer for drivers. The old layers of road were recycled back into the new carriageway using AI’s ex situ cold recycled Foamix asphalt. Foamix is a fully cold process and can be laid and compacted at a much safer ambient temperature which reduces the asphalt fumes on site that workers are exposed to.

The material was mixed on site to minimise vehicle movements and reduce the scheme’s carbon footprint. Using recycled material meant there was less raw material needed for the works too and without the trips to the waste site as well, around 82,000 road miles were saved on this scheme which began in late July 2021. Some 56% of materials were recycled from the old road into the new one. Any remaining material not used in this scheme, which ran between late July and September 2021, was recycled back across the road network through other projects.

National Highways Project Manager, Ryan Davies, said: “We have committed, through our net zero carbon plan, to rapidly cut carbon from road construction, maintenance and operations, and support the transition to zero emission vehicles. 

“A vital part of meeting our ambitious objectives is having the support of our supply chain on schemes such as this. Through close collaboration with partners such as Kier and AI we are taking great strides on our journey to net zero carbon.”

Neil Leake, National Technical Manager at Aggregate Industries, adds: “Good collaboration and an innovative approach were at the heart of this scheme, with people working together to achieve the same low carbon goal. We had some significant challenges to overcome to make sure this scheme could be delivered on time and still meet the low carbon goal we set ourselves.”

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Project details

  • Infrastructure, roads

  • Kier Highways, National Highways

    • 56% of material from old road recycled into new one
    • Old road contained tar-bound material which was processed safely and reused