Passion for Cold Recycling Projects
Whilst growth in cold asphalt using foam bitumen is on the increase, a select few are turning their focus onto emulsion. One of them is Roadways, a UK-based highways construction company that recently carried out resurfacing work in East Sussex. Roadways used Nymuls CP 50 in a cold asphalt binder course made with 100% recycled aggregates, which resulted in 40% less carbon dioxide emissions.
In response to increasingly stringent demands for sustainable and cost-effective pavement solutions, the interest in cold asphalt is growing. In addition to contributing to reduced energy consumption and emissions, cold mixes also allow for the maximisation of recycled materials.
In the UK, cold asphalt has been used for many years, initially on smaller roads and parking lots, but more recently on heavily trafficked highways as well. Several studies from various countries confirm that roads surfaced with cold asphalt exhibit remarkable durability despite long-term traffic exposure.
This is an area of expertise for Roadways, a company with a broad spectrum of operations in highways construction and maintenance, with a strong focus on low carbon and recycled road materials. Even though they are a regional leader, they have proved their expertise and flexibility as a principal contractor for National Highways.
Last year, Roadways carried out resurfacing work in central East Sussex. Eight lane kilometres of high-speed single carriageway was resurfaced to include the binder and surface layers, averaging over 100 mm in depth.
"We produced and laid 3,000 tonnes of cold asphalt binder course in only nine days. It was made with 100% recycled aggregates and resulted in 40% less CO2 emissions. The client needed a fast and cost-effective method as this was a large project for them," stated Roadways Chief Executive James Bailey.
What can be said about the outcome from a sustainability perspective?
“The cold binder saved 54 tonnes of CO2. That's equivalent to driving half a million kilometres in a conventional car or around the globe thirteen times,” James Bailey observed. “Additionally, almost 3,000 tonnes of recycled aggregate was used, sparing natural stone resources from being quarried. An equivalent amount of waste was also reused.”
Roadways is engaged in ongoing discussions with Nynas regarding the use of emulsions with recycled aggregates and recycled asphalt. The collaboration faced a temporary setback due to the Covid-19 pandemic, but as the situation normalised, Roadways decided to modify their manufacturing facility to scale up production, revitalising their partnership with Nynas.
"We have worked with Nynas and their UK Technical Support Manager, Dennis Day, since our research and development into cold materials began six years ago," said James Bailey. "Dennis is extremely passionate about cold asphalt and has been an industry leader and advocate for over 30 years."
"James reached out to Nynas pre-Covid with a commitment to developing cold asphalt using recycled materials," Dennis Day added. "The project in East Sussex is the culmination of our joint collaboration and Roadways' determination to offer lower carbon, sustainable products to its customers."
The product that Roadways uses for these types of surfacing is Nymuls CP 50. The development of Nymuls CP 50 is rooted in the collective experience that Nynas has gained since the 1990s when they began collaborating closely with their customers and suppliers in the UK to develop emulsions for asphalt manufacture.
Nymuls CP 50 has a proven track record, having been used in numerous cold recycling projects nationally. When Roadways articulated their vision in October 2018, it became evident that Nynas' emulsion was the ideal choice to help them achieve their goals.
"Roadways have found that after installing cold asphalt made with Nymuls CP 50 for over five years on main roads and footpaths, it's a robust and stable material," clarified James Bailey. "Easy to mix and lay, it has performed very well in lab testing and hostile live environments such as major bus routes."
The project in East Sussex serves as compelling evidence that cold asphalt can and should be utilised in local projects in the UK, just as it has been in Europe for many years.
"When each truckload of hot asphalt has a carbon footprint of around 9,000 car kilometres, the 40% reduction offered by cold lay cannot be ignored. Many clients are making warm mix asphalt the default for the surface layer. Now is the right moment for cold mix to become the default choice for the base and binder layers," summarised James Bailey.