A section of the M3 in Hampshire has been resurfaced using warm mix asphalt containing the highest proportion of reclaimed asphalt (RA) ever on the strategic road network.
The asphalt includes 70% RA content in the base course and 50% in the surface course, reducing the use of primary materials (aggregates and bitumen) by 55%. Some 1,800 tonnes of planings were taken from a previous project on the M3 and were stored and processed before reuse.
Using warm mix asphalt reduced the production temperature from 180⁰C to 130⁰C, resulting in further carbon emission savings from a reduction in the energy used.
Matthew Wayman, Senior Pavements Advisor at National Highways, said: “We were happy to support this exciting opportunity presented by our supply chain colleagues at FM Conway and Kier Highways, and early collaboration gave us confidence that the materials installed would deliver the same level of performance as conventional materials.
“Although it has been common practice for many years to use a degree of recycled asphalt, this is a major step forward. It will help us reduce the amount of new materials needed which in turn significantly reduces our carbon footprint by cutting the emissions and energy required to excavate, manufacture and transport the materials needed to make the asphalt.”
The section of the motorway – on the northbound carriageway between junctions 6 (Black Dam Interchange) and 5 (near Hook) – will be monitored regularly to assess performance. National Highways (formerly Highways England) will look towards routinely using more recycled content in its resurfacing work, saving carbon and helping it meet its net zero ambitions.