Innovative asphalt ramping up recycling

Trials of an innovative asphalt material have been launched in London with the aim of proving road surfacing materials can perform well with 50% of their content made up of recycled road planings (RAP). Transport for London is carrying out the trials on the A1 near Mill Hill in north London with FM Conway supplying and laying the material.

Up to 50% recycled content is frequently used to produce the lower base and binder course layers in road construction, but the commonly held maximum allowable in surface courses is 10-15% due to concerns over durability and skid resistance. The A1 Mill Hill trial has been set up by TfL to prove that good performance can be achieved with the right design and mixing of the 50% recycled asphalt.

The A1 Mill Hill asphalt has been manufactured to be compliant with Clause 942 of the Specification for Highway Works, with recycled aggregate and binder selected by FM Conway and a special binder performance additive supplied by Arizona Chemical. 

TfL's director of asset management, Dana Skelley, said: “We’re really pleased to be teaming up with FM Conway and Arizona Chemical on this trial for an environmentally friendlier way of resurfacing London’s roads. This unique trial will help us test the durability of 50% recycled asphalt with a view to efficiently implementing this process across the highway network in the near future.”

A surface course material with 50% recycled content is being monitored alongside a conventional asphalt surfacing for comparison of performance.

FM Conway's aggregate and asphalt director, Tim Metcalf, said: "This is an exciting development for the strategic road network. 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. High recycled content asphalt not only meets specified safety requirements, but can support the highways industry in its drive to be more resource efficient as well."