Good News: Recycled Tire Rubber: Roads lasts twice
The rubber from used tires acts as a sunscreen on the roads and reduces the risk of sun damage by half when combined with tar, a new study has found.
New Delhi: The rubber from used tires acts as a sunscreen on the roads and reduces the risk of sun damage by half when combined with tar, a new study has found.
Engineers at RMIT University in Australia have discovered a combination of UV-resistant and durable cargo tar, which has the potential to save millions of dollars on road repairs every year.
Unlike most outdoor infrastructure — such as playground equipment and outdoor furniture — roads are not designed for any protection from the sun, making them prone to cracks and possibly unsafe driving.
Installing recycled rubber not only provides sun protection but is also a promising solution to the problem of used tires in many countries, including Australia where a ban on the export of used tires has been in place since December 2020.
Although research efforts have focused on improving road safety in terms of traffic load, tropical aging and weather-related events, solar damage has received little attention, to date.
Sun protection on the roads
A new study led by RMIT Associate Professor Filippo Giustozzi offers a sustainable solution to UV protection on roads.
"We found that aging was reduced when you applied the scrap rubber, which was recycled from discarded thighs, to the upper layer of the road," said Giustozzi.
“This is as effective as sun protection on the roads that it doubles the surface area beyond normal bitumen.
"We knew that UV would have a devastating effect on the road, but not to the extent that it could protect it, as no one was looking at this factor."
RMIT is one of the few universities in Australia to have a UV machine for asphalt studies, which can mimic weather-related aging and is often used to test exterior furniture paint.
Giustozzi's team used the machine to mimic the long-term effect of solar eclipse in a bitumen lab with a variety of crumb rubber compounds: from a low concentration of 7.5% to 15% and a maximum of 22.5%.
After a month and a half of continuous exposure to UV radiation — about the same amount of radiation exposure in Melbourne, Australia — they measure the changes in chemicals and asphalt machines.
Giustozzi said bitumen mixed with high-density rubber from recycled rubber showed 50% less UV damage compared to conventional tar.
While using more rubber was better about UV resistance, Giustozzi said it was also important to balance this with mechanical performance.
"You don't want anything that can be UV resistant but not resistant to trucks," he said.
"We found that adding between 18% and 22% of crumb rubber produces the right balance in terms of improving decay and fatigue resistance to car loads, while resisting UV wear."
Sustainable solution to the problem of used wheels
Tire Stewardship Australia chief executive Lina Goodman said that while Australia produced about 450,000 tons of tires by 2021, only about 70 percent of those were reused or recycled.
Goodman said they were inspired by research that shows the efficiency and benefits of using rubber from not only non-functional tires, not only on roads and public infrastructure, but in many fields.
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"We are pleased to collaborate on this project with industry and leading researchers at RMIT University," he said.
"The multi-stakeholder approach paves the way for innovation and the opportunity to transform this resource into a value-added product."
Giustozzi said the added benefit of crumb rubber was that it was already widely used, including on some roads, but that councils and state officials were unaware of the 'sunscreen' effect revealed in the study.
"We hope this study will change that and open up new opportunities."