Some 1 billion scrap tires are produced around the world each year, but only a small percentage of all those tires get recycled. Most of the rest end up as plastic waste. Now scientists in Australia have come up with a solution as to what to do with all those unwanted rubber rings: turn them into roads.

The way to do that is to blend rubber from old tires with recycled rubble from building materials to produce a new material that can be used for base layers in roads.

The process has been developed by a team of researchers at RMIT University in Melbourne, who say that the blend of recycled materials meets road safety standards and is more flexible than standard materials, which makes roads less prone to cracking. “Traditional road bases are made of unsustainable virgin materials — quarried rock and natural sand,” says Mohammad Boroujeni, who led the research.

“Our blended material is a 100% recycled alternative that offers a new way to reuse tire and building waste, while performing strongly on key criteria like flexibility, strength and permanent deformation,” he said. “As we push towards a circular economy that can eliminate waste and support the continual use of resources, our recycled blend is the right choice for better roads and a better environment.”

Roads comprise four layers: a subgrade, base and sub-base covered with asphalt on top. All these layers need to be strong enough to withstand the weight of vehicles, but they also need to be flexible because rigidity would cause them to crack. The new rubble-rubber blend has performed well in tests for stress, strength and dynamism, among other features with its low shrinkage and good flexibility reducing the risk of cracking.

Better yet: by turning old tires into useful new materials for roads, we can help solve a major waste problem. “Solutions to our waste problems will come not only from reducing how much goes to landfill and increasing how much we recycle; developing new and innovative uses for our recycled materials is absolutely vital,” stresses Prof. Jie Li, a member of the Australian team.

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