How sustainable is warm mix asphalt?

August 2023

We are now living on a planet of extremes. From extreme weather phenomena to the extinction of various species every single year, the ‘extreme’ has now become the norm. Scientists report that one million species are now on the brink of extinction (1) – and the way we live is at the very centre of the problem.

Just as actions speak louder than words, all corporations now have a duty to act on their promises to slow down the rate at which Earth’s temperature is increasing. Our thirst for knowledge, scientific and technological improvement has been a double-edged sword. While we were waiting for ‘someone’ to do ‘something’, we were still generating global emissions at the previous rate of acceleration.

Our slow-to-react society has meant we are now dealing with roads that are buckling due to extreme heat, increased flooding impacting our current drainage systems, and thousands more potholes every year due to plummeting winter temperatures. These additional challenges are exerting pressure at every step of supply chains. While we try to strengthen our future, we are also repeatedly fixing our attempts from the past.

Where we’re going, we still need roads

Recent reports of roads buckling in the US have not just been down to the heatwave, it’s the result of older and weaker roads expanding beyond their original means – and we cannot fix them fast enough. Global governments managing the strategic road network simply lack the manpower as, like roads, we’ve expanded beyond our means simply out of necessity.

This unique challenge calls for a solution that can help governing bodies lay roads quicker, generate less emissions and improve the performance and durability of our roads in order to resist extreme temperatures for longer. The good news is that we already have the solution: warm mix asphalt (WMA).

Strikingly, only 5-6% of the 25 million tonnes of asphalt we produce in the UK every year is WMA (2),(3). In comparison to the US, we are trailing well behind the 40% of WMA used on American roads (4). Thankfully, in August 2021, National Highways began to accelerate the use of WMA across the UK’s strategic road network, as it’s seen as a lower carbon alternative to hot mix asphalt.

Reasons to make the switch to warm mix

Warm mix offers many benefits over hot mix. One of the main draws for why those in the road sector are making the switch is that it can be produced at temperatures up to 40 degrees lower than hot mix. Not only is this a major saving in terms of energy consumption, helping to cut carbon emissions by up to 15% (5), it’s also a benefit with a multiplicative effect.

Each time asphalt manufacturers lower the production temperature by 10 degrees Celsius, they release approximately 50% less fumes into the atmosphere. With WMA, this means approximately 200% less toxins are released, improving air quality for the workforce at sites and a more comfortable working environment. When laying WMA, cooler temperatures therefore result in less steam, improving visibility at night when most road works take place. Decreased temperatures also mean less cooling time is needed between material layers, increasing workforce productivity and therefore minimising disruption to road users.

WMA also has the capability to deliver a more durable product with a longer lifespan than hot mix. For instance, it removes the risk of oxidisation and binder ageing, which can lead to cracking. In addition, it can be easily manipulated to allow for a higher compaction density, reducing the hardening of bitumen and water admission.

Last of all, warm mix can be fully recycled into new asphalt mix, preventing unnecessary waste for our planet. National Highways estimates that if the UK were to use WMA on all of its production lines, we’d save 61,000 tonnes in carbon emissions annually (6).

Will you make the switch to warm mix asphalt today?

Contact the ACI Flomac sales team to understand where you can save both time and money, while doing your part for the planet.

Remember, sustainability doesn’t have to cost us the Earth!

1. Reuters, Extinction crisis puts 1 million species on the brink, December 202
2. Asphalt Industry Alliance, 2021
3. All Party Parliamentary Group, Working for Better Roads, February 2021
4. National Asphalt Pavement Association, Recycled Materials and Warm-Mix Asphalt Survey, 2018
5,6. National Highways,, 2021

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