Rubber highways have some more twists and turns

‘Asphalt could consume all recycled tyre rubber globally,’ said Redmond Clark, president of Asphalt Plus at the recent Clemson University Global Tire Conference in South Carolina. In his view, rubberised asphalt will become a ‘viable’ application in the coming years if people continue to develop the dry process for crumb rubber modified asphalt.

More than 50% of all recycled rubber is being used in non-sustainable markets, therefore using crumb rubber from recycled tyres is a logical choice for all stakeholders, Clark told delegates. He urged: ‘The window of opportunity is open, but it won’t remain open, because more aggressive industries will beat us to it.’

In the US alone, total demand for recycled crumb rubber in the asphalt industry is estimated at 6 billion pounds per year. Clark observed that this is just as much as American tyre recycling operations could handle annually.

‘Burned with a black mark’

At the moment, approximately 120 million pounds of recycled rubber are transformed into dry crumb rubber modified asphalt (CRM). This figure represents a mere 2% of the market potential, Clark underlined. 

Meanwhile, dry process CRM was developed fifteen years ago, with almost  4 million tons placed so far. Clark estimates that the material covers 1000 lane miles of interstate highway as well as thousands of miles of state and county roads.

So why did the application never really take off? In the early 1990s, several state highway agencies started CRM road construction projects without the proper knowledge of the material and technology involved to back them up. Results were ‘disastrous’, Clark recalled. ‘Rubber has been burned with a black mark ever since.’

A united effort

Eight US states are now in advanced stages of permitting dry process rubber, as are the European Union, China and various nations in the Middle East, Clark reported. Dry process manufacturers are getting more and more market support from the US Tire Manufacturers Association.

The entrepreneur would like to see the tyre recycling industry make a ‘united effort’ to ensure dry process CRM becomes the industry standard, rather than styrene-butadiene-styrene (SBS) polymers-based asphalt. The latter is now more popular than CRM due to it being less expensive. Still, Clark pointed out that dry CRM is more workable at low temperatures, allowing workers to extend the road construction season well into the winter.

‘We should be looking at ways for the tire industry to accelerate the adoption of this technology in the marketplace,’ Clark declared at the conference. ‘The specifications get changed because individual players band together and demand change.’