Highways England accelerates switch to lower carbon asphalts

Highways England is accelerating the use of warm mix asphalts as standard across its supply chain as part of a drive toward net zero carbon emissions.

The government-owned company has been using the material since 2015 and a collaborative programme with the supply chain and extensive research now means it can be used freely across the Strategic Road Network (SRN).

Those involved from the supply chain include Balfour Beatty, Kier, Morgan Sindall, Costain, Skanska, Galliford Try, Bam Nuttal, and Osborne.

Previously requiring an application for a departure from standard, Highways England is now asking all those involved in the construction and/or maintenance of the strategic road network, particularly designers and main contractors, to utilise warm mix asphalts (WMAs) as it moves towards net zero.

WMA technologies can offer enhanced efficiencies and lower production carbon, with CO2 savings of up to 15% when compared to conventional hot mix asphalts.

While typical asphalts are produced at up to 190°C, the simple principle behind WMA technologies is to manufacture asphalt at reduced temperatures but with additional additives, thereby using less energy and delivering meaningful carbon savings, without compromising performance.

Produced at temperatures up to 40°C lower than traditional asphalt, if all production in the UK switched to WMAs, it would save around 61,000 tonnes of CO2e a year, the equivalent of cutting around 300 million miles of car journeys.

It would also help save up to £70m a year through an increased in shift outputs and can be recycled back into new asphalts, preventing waste. WMAs can be laid using existing equipment and brings other benefits, including:

• Carbon reduction: the lower production temperatures of WMAs reduce the carbon emissions associated with asphalt production by up to 15% compared to Hot Mix Asphalts. More widespread use of WMAs will help Highways England to achieve its aim of net zero by 2050;
• Increased productivity: reduced laying temperatures mean that WMAs take a shorter time to cool so greater volumes of asphalt can be laid in one shift, or the finished surface opened earlier to traffic without the risk of the material deforming under heavy loads. This will increase productivity by enabling more material to be laid within a working window, reducing the overall timeframe of the works and potential delays to motorists;
• Improved health and safety: reduced temperatures also help to reduce the health and safety risks associated with both production and laying of asphalt at high temperatures such as burns, exposure to fumes and the impact of steam on visibility, particularly when wearing safety eyewear. With WMAs, fume generation is reduced by around 50% for each 10°C reduction in temperature;
• Improved durability: due to being laid at lower temperatures and the increased amount that can be laid in a single shift, it also means less construction joints in the road requiring less maintenance in the future. This again increases the long-term benefits of the technology, life-time cost and need to undertake further maintenance.

Malcolm Dare, executive director of commercial and procurement at Highways England, said: “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. 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 warm mix asphalts as standard across the supply chain, which has efficiency, sustainability, and health and safety benefits whilst not compromising performance."

Paul Gott, project sponsor from Morgan Sindall Infrastructure, said: “We are delighted that we’ve formed a group from across the supply chain who are focused on embedding carbon reduction measures across Highways England’s schemes. Warm mix asphalt is the first carbon efficiency project on the groups extensive carbon reduction plan, which is evolving and already identifies several short, medium and longer-term goals.”

Tim Jordan, project delivery lead from Balfour Beatty added: “We are proud to be working collaboratively with both Highways England and our industry partners to drive meaningful, sustainable change in the supply chain as we work towards a net-zero future.”