How Tires are Recycled to Pave Roads

Some roadways are paved with recycled tires.

In the United States about 290 million tires are thrown out every year. They end up in landfills, huge stockpiles and empty lots. Discarded tires can create fire hazards and become a breeding ground for pests. One way to reduce this ever-growing waste is to recycle it into paving material for roads.

Initial breakdown of material

When scrap tires arrive at a recycling center, they are shredded and the metal components are removed. After most of the metal is gone, the rubber is further broken down into small granules which can be used in many different industries.

Melting process

For road surface use, the rubber granules are mixed with asphalt and then heated to a temperature between 350 and 450 degrees. The resulting mixture is cured, forming a gel called asphalt-rubber. The asphalt-rubber is mixed with stone and sand to make paving material.

Benefits

Adding rubber to asphalt improves its durability, flexibility and susceptibility to cold. Although adding rubber increases the costs of the paving material, asphalt-rubber lasts about twice as long as ordinary asphalt. According to the CBS website BNET, asphalt-rubber pavement only needs to last about 3 months longer than ordinary pavement to earn back manufacturing costs.

References

• Earth 911: Facts About Tires
• Earth 911: Benefits of Recycling Tires
• "Resource Recycling"; Recycling Tires into Asphalt; Russell J. Schnormeier; January/February 1988
• BNET: Rubber to the Road