Is rubber asphalt the road building material of the future?

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“Rubber Roads” could help to cut motorway maintenance costs and carbon emissions.

As a by-product of an industry that exists all over the world – the used tyres that remain after their life on vehicles has ended – ground tyre rubber also helpfully has resilient properties that can be used to enhance the performance of construction products.

For the asphalt industry, which currently depends on materials with very high embedded energy costs – polymer-modified bitumen is expensive in carbon terms both to make and to transport and store – asphalt made using bitumen modified with rubber concentrate from ground recycled tyres could therefore offer a welcome solution to greenhouse gas emissions associated with traditional asphalt manufacturing.

And because new roads made with bitumen modified with rubber will last longer as a result, both government and industry could save millions of pounds as well as thousands of tons of C02.

Of course, there’s nothing new about using recycled tyre rubber in road surfacing– people have been doing it for over 50 years, but the key to unlocking the full potential of so called rubber asphalt is the technology i.e. ‘how to get’ the recycled tyre rubber into the asphalt, which is exactly what one UK company has managed to do.

BillianUK, founded by Bill Bolsover CBE, the current chairman of the Strategic Forum for Construction, are using innovative technology, first developed in the USA, to improve traditional ways of modifying asphalt. The company says its new product, called GTR Paving Pellets, will help to make better quality roads more sustainable and more widely available.

The Billian technology relies on a simple yet highly effective process of harnessing the resilient properties of rubber in small easy to use pellets, about 10mm in size. The pellets are designed to act as a delivery mechanism for the rubber concentrate, which begins life as recycled ground tyre rubber – the GTR in the product – before being blended with bitumen and then converted into pellets.

Because pellets are manufactured at a single processing facility, in Sheffield, and then transported to an asphalt plant at ambient temperature, all of the issues concerning storage stability and degradation associated with hot bulk liquid modified bitumen are removed.

Billian claim the technology will enable all asphalt plants to make modified higher performance asphalt and the versatility of this technology offers opportunities to increase profit margins, expand the use of performance asphalt s in the UK, improve efficiency and self‐promote a “green image” for recycling, energy savings and environmental stewardship.

“Because of the unique physical properties of the GTR paving pellets there are many more options for using them than for using conventional polymer modified bitumen,” said Billian UK General Manager Gareth Evans.

Bitumen is normally transported in heated road tanker and the shipping distances are dependent upon the ability to maintain heat or reheat the material such that it can be pumped. GTR paving pellets are transported in bulk solid form at ambient temperature in quantities to suit the customer from 5kg low melt to 1t bulk bags, before being added directly into the asphalt mix. Unlike conventional paving grade or modified bitumen, pellets do not need to be heated before use. The low temperature storage also prevents any degradation of the product whilst in storage for extended periods.

“Our product enables all asphalt plants to make almost any type of asphalt they like, in any quantity, at any time, with no waste and no need for energy intensive heated storage tankers,” Mr. Evans said. “ They (asphalt manufacturers) can make whatever they want by simply dosing the asphalt mix with the GTR Paving Pellets to make superior performing asphalt.”

According to Mr Evans, rubber modified bitumen ‘has a strong track record across Europe and USA’ and is acknowledged by highway engineering experts as a method of ‘providing high performance in asphalt’.

“There is no disputing the fact that it makes good sense.” Mr. Evans said. “Reusing ground tyre rubber from recycled tyres as a bitumen modifier not only lowers the environmental and social impact of asphalt, both socially and economically, but it also has the potential to significantly reduce asphalt production costs by negating the need for costly polymer-modified bitumen (PMB) and the highly energy-intensive heated tanks used for storing hot liquid PMB.

“Anything we can do to make roads last longer is a good thing. We have known how to do this for years. GTR Paving Pellets simply help to make it more achievable. There is currently a massive demand in the UK for better quality more durable roads. One in five of our roads is in poor condition, which means they have less than five years of life remaining – currently a £10.5bn problem.”