Rubberized asphalt

Rubberized asphalt is pavement material that consists of regular asphalt concrete mixed with crumb rubber -- ground, used tires that would otherwise be discarded or take up space in landfills. Asphalt rubber is the largest single market for ground rubber in the United States, consuming an estimated 220 million pounds, or approximately 12 million tires annually^[1].

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Use of rubberized asphalt as a pavement material was pioneered by the city of Phoenix, Arizona in the 1960's because of its high durability^[2]. Since then it has garnered interest for its ability to reduce road noise.

In 2003 the Arizona Department of Transportation began a three-year, $34-million Quiet Pavement Pilot Program, in cooperation with the Federal Highway Administration to determine if sound walls can be replaced by rubberized asphalt to reduce noise alongside highways. After about one year, asphalt rubber overlays resulted in up to a 12-decibel reduction in road noise, with a typical reduction of 7 to 9 decibels^[3].

Arizona has been the leader in using rubberized asphalt, but California, Florida, Texas, South Carolina and New Mexico are also using asphalt rubber. Tests are currently underway in other parts of the United States to determine the durability of rubberized asphalt in northern climates, including a 1.8 mile stretch of Interstate 5 between Everett and Seattle Washington^[4] and a handful of local roads in the city of Colorado Springs, Colorado^[5].

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