Warm mix asphalts

The challenge

One of many steps we’re taking to reduce our carbon emissions is encouraging the use of warm mix asphalts (WMAs) as standard across our supply chain.

Typical asphalts are produced at up to 190°C.

The simple principle behind WMA technologies is manufacturing asphalt at reduced temperatures but with additional additives

This uses less energy and delivers meaningful carbon savings without compromising performance.

The project

WMA is produced at temperatures up to 40°C lower than traditional asphalt.

If all production in the UK switched to WMA, it would save around 61,000 tonnes of CO2e a year. This is equivalent to cutting around 300 million miles of car journeys.

With a shorter cooling time and reduced risk of early life deformation, WMA allows longer working windows and increased shift outputs. It can also be recycled back into new asphalts, preventing waste.

In addition to carbon reduction and increased productivity, some of the other key benefits of switching to warm mix asphalts include:

Improved health and safety

Reduced temperatures help reduce risks associated with producing and laying asphalt at high temperatures such as

• burns
• exposure to fumes
• steam causing reduced visibility, particularly when wearing safety eyewear

WMA reduces fume generation by around 50% for each 10°C reduction in temperature.

Improved durability

As WMA is laid at lower temperatures and an increased amount can be laid in a single shift. It needs fewer construction joints in the road and less maintenance in the future.

Next steps

Our next step is encouraging everybody involved in building and maintaining the strategic road network, particularly designers and main contractors, to use WMAs.

More widespread use of WMA will help us achieve our aim of net zero carbon maintenance and construction activities by 2040. Best of all, WMAs can be laid using conventional paving equipment.