Paving the way to greener road resurfacing

A ground-breaking trial between FM Conway and Transport for London has demonstrated the untapped potential to increase asphalt recycling on the strategic network.

Andy Walker
16 November 2016

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Asphalt recycling is essential for the highways industry’s present and future.  Reusing recycled planings from existing roads helps to mitigate the lack of high Polished Stone Value (PSV) aggregates in the south east, reduce the sector’s reliance on primary materials and make road maintenance more resource efficient.  

In practice, however, industry perceptions of recycled asphalt have hindered the opportunity to use more of these materials on strategic roads. While it’s not unusual to incorporate 50 per cent recycled content into the base and binder layers on strategic routes, there are misconceptions that high recycled content mixes cannot provide adequate skid resistance and durability.  As such, the recycled content of surface course mixes has traditionally been limited to around 10 per cent.     

To challenge this notion and establish if it’s feasible to use higher percentages of recycled asphalt on strategic roads, Transport for London (TfL) appointed FM Conway to lay an asphalt surface course containing 50 per cent recycled aggregate constituents on the A1 Mill Hill.  

This unique trial is being carried out on three lanes of the strategic highway and the recycled content mix will be monitored against primary aggregate asphalts to ensure its durability and retention of a skid resistant surface course. The material laid incorporates FM Conway’s specially designed binder and prepared secondary aggregates, as well as a Sylvaroad performance additive from Arizona Chemical.

Dana Skelley, TfL’s director of asset management, said: “We’re really pleased to team up with FM Conway and Arizona Chemical on this trial for an environmentally friendlier way of resurfacing London’s roads. The unique trial is helping us test how durable recycled asphalt is with a view to efficiently implementing this process across the highway network in the near future.” 

While a long-term study of the pavement’s performance will now be conducted, Tim Metcalf, director of aggregates and asphalt at FM Conway, believes the trial has the potential to transform the way Britain’s strategic road asset is maintained.  

“We’re confident that the trial will answer any doubts about the use of high recycled content asphalt for both surface courses and the base and binder courses of strategic roads.  It not only meets specified safety requirements, but can support the highways industry in its drive to be more resource efficient. 

“With the high volumes of asphalt required by Highways England’s roads investment programme and the lack of virgin aggregates needed to meet London and the south east’s highways requirements, there is a critical need to maximise existing resources and recycle the asphalt that’s currently within our roads,” said Metcalf.