Asphalt road at sunset

Highways England encourages low-carbon asphalt as default

Image credit: Highways England

UK government-owned Highways England is accelerating the transition to low-carbon asphalts, offering for all those involved in the construction and maintenance of the strategic road network to use warm mix asphalts (WMAs).

Highways England, which has been using the material since 2015, has announced that WMAs may be used freely across the strategic road network.

WMAs account for over 15 per cent of asphalt production in France and almost 40 per cent in the US, but only around four per cent in the UK. Previously, use of WMAs required an application from the supply chain, as a departure from standard. More than 250 applications have been filed to use WMAs on the strategic road network at over 300 locations.

WMA can offer enhanced efficiencies and lower carbon emissions associated with production, with carbon reductions of up to 15 per cent compared with conventional hot mix asphalts. Hot mix asphalts are heated to temperatures around 190°C, while WMAs can be produced 20 to 40°C lower thanks to certain additives. This allows for lower energy costs and carbon intensity, without compromising performance or requiring different equipment.

Switching to temperatures 40°C lower than hot mix asphalts for all production in the UK would save around 61,000 tonnes of carbon each year (equivalent to 300 million miles of driving).

“This is a big step forward for Highways England that allows us to not only achieve huge efficiency savings but also reduce carbon as we strive for net zero,” said Malcolm Dare, a director at Highways England. “Carbon reduction, along with ensuring our roads provide smooth, safe and efficient journeys for motorists, are key and something we are constantly striving to improve for generations to come.

“That’s why we are altering our way of working to encourage and enable the use of [WMAs] as standard across the supply chain, which has efficiency, sustainability and health and safety benefits, while not compromising performance.”

The government states that this would also help save £70m annually through an increase in shift outputs – as reduced laying temperatures mean shorter cooling times, so greater volumes of road can be laid in a single shift or the surface opened to traffic earlier without risk of deformation. This also has the advantage of improved durability, due to fewer construction joints.

Malcom Simms, director of the Mineral Products Association, commented: “We and members have been working closely with Highways England for a number of years to provide the evidence of the benefits of [WMAs], in order to give specifiers the confidence to make a shift to these solutions. This is a significant first step on our collective and challenging net-zero journey and it’s great to see lower carbon asphalts being enabled as a matter of routine, rather than by exception.”

Highways England aims to cut carbon from road construction, maintenance and operations amid the broader transition to net-zero carbon emissions by 2050. It has set targets of 2030 for net-zero in its own operations; 2040 for maintenance and construction, and 2050 for travel on its roads.

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