Aussie researchers may have created sunscreen for roads
New research has found that adding used tyres to bitumen in new roads could halve the rate of sun damage to roads, potentially saving millionsResearchers at Melbourne’s RMIT University have found a way to reduce the degradation of roads while tackling Australia’s increasing used tyres crisis by combing recycled rubber with bitumen.
By adding used tyres to fresh bitumen, researchers found that the used rubber material effectively acted as a form of ‘sunscreen’ for the road, with recent testing revealing that roads with an optimal blend of recycled rubber showed 50 per cent less UV radiation damage when compared with regular road material.
Sun damage slowly leads to the degradation of road surfaces, which eventually form cracks. The deterioration can eventually render the road unsafe, necessitating costly road repairs and ongoing maintenance.
From 2019 to 2020, road maintenance totalled $2.9 billion (National Transport Commission data), so the potential savings by using bitumen with recycled rubber are huge, says RMIT. And at the same time, harnessing the vast stockpiles of used tyres in this country will help alleviate another problem that is only accelerating – Australia has had an export ban on used tyres in place since the end of 2020.
The new research is a collaboration between RMIT and Tyre Stewardship Australia (TSA), which promotes the development of viable markets for end-of-life tyres. Previous work has focused on traffic load, thermal ageing, and weather-related events, but sun damage to roads had previously received little attention.
According to Associate Professor Filippo Giustozzi, the new research opens up new worlds of possibilities.
“We found that the ageing trend is actually slowed down when you add crumb rubber, which is recycled from scrap tyres, into the top layer of a road,” Giustozzi said.
“This acts so effectively as a sunscreen for roads that it actually makes the surface last twice as long as regular bitumen.
“We knew that UV would be a factor in road degradation, but not by what degree or how to protect against it, as nobody has really been looking at this aspect.”
RMIT utilised a UV machine traditionally used to assess the impact of UV on paint to conduct its research. Researchers studied the effects of using different concentrations of crumb rubber in the bitumen, to arrive at an optimal blend that maximises UV protection while balancing this with mechanical performance.
“You don’t want something that is UV resistant but not truck resistant,” said Giustozzi.
“We found adding between 18 per cent and 22 per cent of crumb rubber generates an ideal balance in terms of improving rut and fatigue resistance to traffic loads, while resisting UV ageing.”
Researchers now hope that the findings, which were published recently in the Journal of Cleaner Production, will encourage local and state authorities to, where possible, adopt the practice on a widespread basis.
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