ecovote.org > get involved > action alerts > solid waste
Flattening out toxic mountains
Crumb rubber from scrap tires: the ultimate example of recycling for sustainability
California generates 32 million scrap tires each year and is expected to generate more than 43 million scrap tires annually by 2020. Approximately six million such tires currently sit in toxic scrap tire piles, even though state policy discourages stockpiling and encourages both recycling and alternative uses. Several years ago the nation’s largest waste tire pile, near Modesto, caught fire and burned for weeks, polluting the air and soil. Simply discouraging stockpiling is not enough and will not keep up with the ever-growing mountain of toxic waste scrap tires accumulating throughout California.
Assembly Bill 338 (Levine) instructs Caltrans to gradually phase in the use of rubberized-asphalt concrete (RAC), which is made from crumb rubber derived from scrap tires, on state highway construction and repair projects. The bill not only acts to reduce our state’s growing waste tire piles but also will result in substantial savings. Since RAC is more durable and has a significantly longer lifespan than conventional asphalt, AB 338 will eventually save the state $2 million annually or more.
Crumb rubber is produced by recycling used tires, which are first shredded and then run through magnets and filters to separate steel belting and nylon mesh. Continued shredding and filtering reduces the rubber particles’ size to an inch or less in diameter, producing useful “crumb rubber.” Numerous studies, including a University of Illinois study conducted in 2000, concluded that rubber-modified asphalt has been shown to last up to three times longer than conventional asphalt on roadways.
Caltrans began testing RAC as early as 1978. It has used RAC on numerous state highway repaving projects (i.e., a 10-mile stretch of Interstate 10 near Blythe, as well as a segment of Interstate 880 in the San Francisco Bay Area). These tests have shown that this cost-effective pavement overlay process increases the life of the roadway and reduces maintenance because RAC is durable, resists cracking, and drains better than traditional asphalt.
The use of rubber-modified asphalt has spread throughout several countries, including Germany, Japan, and Australia, as well as the states of Arizona, Florida, and Texas. The Arizona Department of Transportation used crumb rubber in nearly 22% of their projects in 2003.
Governor Arnold Schwarzenegger vetoed a nearly identical previous version of AB 338 last year over fears that the bill, which required CalTrans to use tires originating in California, violated the North American Free Trade Agreement (NAFTA). Those concerns have been addressed in this year’s bill, yet CalTrans now opposes the bill’s requirements and wants only an unenforceable goal for their use of recycled rubber from scrap tires. AB 338 is on the Governor’s desk and must be signed or vetoed by October 8th.
