While piles of discarded automobile tires used to be an eyesore or a fire hazard, today there are many methods to recycle tires and put the material to good use.

According to the Environmental Protection Agency, at least 290 million scrap tires are generated in the United States each year. In the past, the vast majority of scrap tires ended up in landfills or scrap yards. Piles of discarded tires became an eyesore, breeding grounds for mosquitoes, and even fire hazards, as a tire fire could take days and many resources to put out. Fortunately, there are a variety of applications by which scrap automobile tires can be reclaimed, reused and recycled. Today, only about 10 percent of all scrap tires end up in landfills, thanks to several useful applications for tires and tire rubber.

Incinerating Tires for Energy

The largest fraction of reclaimed scrap tires, or about 45%, according to the EPA, are incinerated as a fuel. Scrap tires can either be incinerated whole, or shredded first and then incinerated. Tire rubber contains approximately the same energy density as oil, and its emissions contain fewer toxins than coal. The primary user of tire-derived fuels is the cement industry, where the fires fed by tire rubber are used to manufacture clinker, one of the steps in the cement making process. Other users of tire-derived fuels are paper pulp mills and power utilities.

Reusing Whole Tires

Scrap tires can be used in whole or in large part for a variety of applications. Whole tires are often used for highway crash barriers or bumpers for marine applications. People can reclaim individual tires as planters for urban settings or classic tire swings. Tires are also often recycled by cutting them into various rubber products after the steel belting has been removed. Products created from parts of whole tires include floor mats, belts, shoe soles, and washers.

Grinding Tires into Crumb Rubber

Ground tire rubber, also referred to as crumb rubber, is one of the fastest growing applications for scrap rubber. The tires are shredded and ground into a granular texture, and often added to another product as an aggregate.

The primary application for crumb rubber is asphalt. Adding crumb rubber to asphalt increases the longevity of the roadway and improves driving conditions. Shredded rubber is often used in civil engineering applications, such as subgrade fill and embankments, and septic system drain fields.

Another widespread use for crumb rubber is in recreational facilities, including athletic fields and playgrounds. Crumb rubber is used as an aggregate in the material for running track surfaces, and is added to soil in grass playing fields to increase resilience and drainage.

In addition, cutting edge processing techniques derived from pharmaceutical applications allow scrap rubber to be pulverized into powders as fine as talc. The Florida company Lehigh Technologies developed this method so that "the powder can be used in manufacturing products that would benefit from the durability of rubber, such as longer-lasting paint, UV-resistant plastics and more elastic sealants."

While scrap automobile tires used to contribute significantly to the contents of landfills, today there are a variety of innovative recycling methods that use the inherent benefits that scrap rubber can provide to improve applications from roadways to playgrounds.

Sources

Environmental Protection Agency website.

CNN website, "Scrap Tires Tread New Ground as Powder", February 4, 2008.