Construction, renovation, and demolition account for about half the waste produced annually worldwide, while around 1 billion scrap tires are generated globally each year. The two issues may not seem to have a direct link with one another, but scientists in Australia have blended the two sources of waste into a material that may make our roads more durable and sustainable.

The idea comes from a team of engineers at Melbourne’s RMIT University and builds upon the fact that building rubble that is crushed and processed can be repurposed as a building material called recycled concrete aggregate (RCA).

RCA can then be integrated with other building materials to lessen their environmental footprint, and eventually, find good use in different sectors of the construction industry.

In this case, the researchers decided to research different materials that, when added to RCA, would form a suitable candidate to replace one of the base layers our roads are made of – more specifically, the base layer that sits above the subgrade and sub-base layers and below the asphalt on top.

After experimenting with a number of additives that could improve RCA’s performance in this area, the scientists found that crumb rubber taken from scrap tires fits the bill nicely.

The team established that makeup of 0.5 percent fine crumb rubber and 99.5 percent RCA ticks quite a few important boxes. Using special machinery to test its performance, the team found that the recycled blend is more flexible than standard materials, making roads less prone to cracking, all while offering a greener approach to construction.

“As we push towards a circular economy that can eliminate waste and support the continued use of resources, our recycled blend is the right choice for better roads and a better environment,” says lead researcher Dr. Mohammad Boroujeni.