The UK is ready for rubber – Tarmac’s new asphalt solution

A huge surplus of waste tyres and a strengthening commitment towards sustainability from local authorities has prompted asphalt supplier Tarmac to invest in technology to add crumb rubber to its mixes "Local authorities want to be green, sustainable and environmentally friendly,” said Tarmac’s technical director Brian Kent. “I get the sense that these issues are more important to them now. I do think we are going to get some traction.” Around 40 million tyres are worn out every year in the UK. Though
September 6, 2019 Read time: 3 mins
Tarmac is now using crumb rubber in asphalt
A huge surplus of waste tyres and a strengthening commitment towards sustainability from local authorities has prompted asphalt supplier Tarmac to invest in technology to add crumb rubber to its mixes


"Local authorities want to be green, sustainable and environmentally friendly,” said 2399 Tarmac’s technical director Brian Kent. “I get the sense that these issues are more important to them now. I do think we are going to get some traction.”

Around 40 million tyres are worn out every year in the UK. Though some are burnt for fuel at cement kilns, others turned to crumb rubber and used for sports pitches and to create items like car mats, there is still a surplus of 120,000tonnes of rubber waste. Currently these are shipped abroad.

Tarmac has modified seven of its 72 asphalt plants so that 1% of crumb rubber by weight can be added to mixes. This is combined with a warm-mix additive, Evotherm, so that the harmful emissions are not produced during the manufacturing process. Tarmac reckons this equates to 750 waste tyres/km of road resurfaced.

The company started investigating the use of end-of-life tyres (ELT) in asphalt back in 2011. They chose a method has been used successfully in the US for over a decade, said Kent.

This process is somewhere between the wet and dry processes for adding rubber to asphalt mixes. The rubber become part of the asphalt matrix, melting at first and then resolidifying to act “like a glue”, said Kent.

The result is a mix that is better than one created with standard bitumen, but not as enhanced as one made with a polymer-modified bitumen. Kent did not provide any test results to demonstrate its performance, saying that there were no tests that adequately mimicked ageing.

“Talking to colleagues in America, they have come to the conclusion that because rubber is in the material, it is helping to delay crack propagation and that means the roads are lasting longer,” said Kent. He added that where rubber is used in SMA (stone mastic asphalt) mixes, the crumbs sit in some of the air voids, improving waterproofing and hence enhancing durability.

The first UK authority to trial the mix was Coventry, with national authority Highways England also carrying out a trial on the M1 motorway near the East Midlands Airport. Authorities in London, Nottingham and Leicester are also planning trials with several others expressing interest.

Modifications to the asphalt plants involve adding an automated system to the plant which includes a silo, a screw to mix and making modifications to the software. The cost for modifications varies, depending on the plant but costs tens of thousands of pounds. Other plants will be upgraded, depending on market demand, says Kent.

Materials

For more information on companies in this article

Related Content

  • How waste plastic and soybean oil are helping our roads last longer
    April 13, 2018
    A clear polymer-modified binder (PMB) combined with carefully selected aggregates has helped restore an ageing promenade in Morecambe, a popular seaside resort on the West coast of Northern England. As part of a £10 million project to upgrade the seawall in the town, Lancaster City Council procured a new promenade as the existing one had suffered from longitudinal cracking. Given Morecambe’s important tourist industry, aesthetics – as well as longevity – were an important consideration. Contractor VBA work
    Read More
  • Innovative low temperature asphalt and aggregate options and advances
    May 16, 2014
    Studies show the asphalt sector has options for materials use that can lower costs and emissions, as well as increasing the use of recycling One study in the UK led by the Carbon Trust and Lafarge Tarmac has found that low temperature asphalt (LTA) could be used as an alternative to conventional asphalt on roads. Conventional asphalt is made when aggregates and bitumen are bound together at temperatures of between 180ºC-190ºC. However, the trial found that the alternative is able to bond road materia
    Read More
  • Warm mix/cold climates
    February 28, 2012
    MeadWestvaco (MWV) says that its Evotherm warm mix asphalt technology is now approved by the Colorado Department of Transportation (Colorado DOT) for use in statewide paving projects. The warm mix asphalt system can be used in any traditional hot-mix asphalt application, but with significantly lower temperatures required for paving application. This feature is particularly useful in Colorado's high altitude paving projects and has been tested extensively.
    Read More
  • Advancing asphalt plant technology
    June 9, 2016
    Advances in asphalt plant technology were in major evidence at the bauma 2016 exhibition in Munich - Mike Woof writes One of the most apparent developments at bauma 2016 was the strong focus on asphalt plant technology. The massive physical presence of the asphalt plants could be seen from a distance, right across the showground, particularly the 50m-high machine Benninghoven had opted to exhibit. However, other plant systems from rival firms Ammann, Lintec and Marini, as well as Turkish company E-MAK, c
    Read More

Highlighted Content