What Happens To Old Tires? Many Of Them End Up Paving New Roads

Tires have many useful applications even after they're worn out, such as swings, retaining walls, and flower planters. They can even be shredded and incorporated back into the roads we drive on, providing some benefits that pure asphalt does not keeping them out of landfills. Ongoing research continues to figure out the best ways to do this, but some places have already made the rubber meet the road and are enjoying the benefits of these surfaces.

In the U.S., states such as Arizona, California, Florida, Georgia, and Texas have either done extensive research on rubberized roads or already put them into use. California leads the way, with state laws requiring Caltrans to use recycled tire rubber in 35 percent of its road projects, according to Chemical and Engineering News. Part of California's motivation comes from a 1999 tire fire in Westley that was so large it gave the Springfield Tire Fire from "The Simpsons" a run for its money. Georgia has also been successfully using recycled tires in pavement along The Ray, an 18-mile stretch of Interstate 85 that experiments with many new technologies, from rubberized asphalt to solar EV charging and V2X communications. Georgia is also using it to repave some roads in downtown Atlanta in preparation for the FIFA World Cup, according to Fox 5 Atlanta.

A study by Charles Darwin University highlights the limitations of pavement in temperate areas, which often do not perform well in hotter regions, such as Australia's Northern Territory. (This region, being closer to the equator in the Southern Hemisphere, is hotter than more southern regions.) Creating a special polymer that's more durable in warmer climates would be more expensive than shredding old tires and leveraging those similar properties in their rubber. It is also more durable than traditional pavement compounds, extending pavement life by up to 50 percent according to Rubcorp. The Arizona Department of Transportation has been using rubberized pavement for some time, and says that some rubberized roads can last over a decade. Arizona claims to have invented it, according to Cronkite News, and it is particularly well-suited for the desert environment.

The compound also reduces road noise, since the rubber helps absorb some of the sound that tires create just by rolling down the road. This benefits not just people inside the cars that drive these roads, but also people who live and work near them, and won't have to put up with as much noise. Arizona DOT says that rubberized pavement reduces tire noise by approximately four decibels in neighborhoods near urban freeways. It also doesn't absorb as much heat, which means it doesn't release heat when the sun goes down and reduces overnight temperatures, something Atlanta may appreciate during the World Cup games.

Rubberized pavement is a great idea, offering numerous benefits. However, it's not a one-size-fits-all solution. It is less durable than traditional pavement in cold climates. The rubber that remains soft and flexible in the heat instead becomes harder and more brittle, and the road would be even more likely to break up than traditional pavement. This is likely why the states currently using rubberized pavement are all in the southern U.S. It's all about using the right tool for the right job.