Prolonged sun exposure is one of the main contributors to asphalt cracking. That’s because the heat from the sun dries up the road’s moisture content, making it brittle and prone to wear. A team of scientists has found that adding rubber from old tires to asphalt can help roads last twice as long before developing cracks.
Addressing two environmental problems at once
The team of researchers at Australia’s RMIT University has come up with an eco-friendly solution that can protect roads from the harsh rays of the sun. The method involves adding crumb rubber from scrap tires to the road recipe — addressing both the environmental impacts of road maintenance and the waste problem of discarded tires.
As part of the study, the team tested the protective effects of crumb rubber by adding it to the top layer of asphalt in three different concentrations — 7.5 percent, 15 percent, and 22.5 percent.
The researchers then accelerated the aging process of the three road samples by exposing them to high levels of UV light for a month and a half — the equivalent of what roads would withstand over 12 months. The final stage involved measuring and comparing the changes in physical and chemical properties of all three road samples.
The team found that the sample with the highest concentration of crumb rubber showed the highest resistance to wear. With that said, going beyond 22.5 percent might start interfering with the road’s endurance to mechanical damage.
“We found adding between 18 percent and 22 percent of crumb rubber generates an ideal balance in terms of improving rut and fatigue resistance to traffic loads while resisting UV aging,” said study lead author Filippo Giustozzi. “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.”
Source study: Journal of Cleaner Production — Exposure of crumb rubber modified bitumen to UV radiation: A waste-based sunscreen for roads