Tests of permeable asphalt at the University of Melbourne. Photo by Holly Bennett, University of Melbourne

Every year, Australia discards some 51 million used tires. The country’s notorious problem – famous Stawell tire dumping site in Western Victoria can serve as a proof that the country puts its environment in a dangerous position.

The country recycles only 5 per cent of waste tires. Today, scientists from the University of Melbourne are working on a clean environment initiative investigating the ways how tire rubber could be reused. The researchers work in association with Tyre Stewardship Australia and Merlin Site Services.

Innovative ways to apply recycled tires for permeable pavements have been studied for more than a year by Dr. Mahdi Disfani, who represents the Melbourne School of Engineering and his partners Associate Professor Lu Aye, Dr. Guillermo Narsilio and Dr. Alireza Mohammadinia.

According to Dr. Disfani, at present, recycled tires are often and successfully used in playground construction, rubber-modified asphalt and in landscaping projects; however, the potential of tires for the application in high volume still needs to be revealed.

Permeable pavement, which will be developed with the waste tires currently kept at landfills, could help reduce the number of dumped tires, as there are many pavements and roads requiring regular maintenance and improvement. Moreover, this innovative way of pavement construction is convenient and reliable, thus it has already gained some popularity.

One big advantage of permeable pavement over the traditional asphalt is that it is capable of allowing water to pass through the surface, which prevents water pollution and storm water overflow. One can say that this pavement’s flexible nature makes it unfit for roads. However, this soon can change, as Dr. Disfani and his colleagues are now developing the finest combination of paving using recycled tires, which will prevent cracks that normally appear on the surface due to tree roots growth and earth movement. At the same time, the scientists will make the pavement resilient under heavy traffic.

According to Dr. Disfani, to attain this goal, the researchers will need to find the perfect combination of recycled tire elements, the binder and rigid rock masses.

The University of Melbourne campus now hosts the trial of four various pavement combinations. Each of the blends will be used for different purposes, including footpath development, paths for bikes, parking surface and light traffic roads.

Researchers also closely study the pavement qualities, such as skid resistance, which can ensure safe travel for pedestrians and drivers.

Given that big Australia’s cities suffer from poor storm water control, the scientist believes his initiative will be able to help reduce pollution in waterways and will also preserve water.

Whenever there is heavy rain in Melbourne, the city’s busy areas immediately start suffering from flooding. In addition, the permeable pavement’s specific structure will let sufficient amount of water in and will also supply a number of local gardens and water collection systems, said Dr. Disfani.

If the design is modified and if additional coats are laid beneath the surface, it is possible to prevent run-offs, even if Melbourne experiences severe rain.

Nevertheless, switching to permeable pavement can be challenging, added the leading project scientist. Dr. Disfani warned that the great challenge is blockage, which can happen as a result of rubbish and residues filtering. This filtering capacity will need to be worked on, so a pavement can remain safe and resilient for traveling.

At the early stage, the testing has shown promises. Thus, Liam O’Keefe, who represents Tire Stewardship Australia, believes that the project can really make a difference.

According to him, once the perfect combination for the pavement is verified and the value is distinguished, the scientists will move to the following stage of larger testing, considered beneficial for the environment, as it will deal make use of thousands of dumped tires.

Today, the cost for permeable pavement is rather high, however the researchers are developing the product, which could be reasonably priced and could be flexible enough.

The innovators, O’Keefe and Dr. Disfani, are seeking the goal to reduce the number of scrap tires, which are stockpiled or exported abroad, thus there is a need to develop a strong market for recycled tires.

Article sources: Waste Management Review