Illinois county hitting the road with rubberized asphalt

DuPage County in Illinois is testing rubberized asphalt as part of its summer repaving program. Recycled, ground-up tires mixed with asphalt to a depth of 2 inches will cover Army Trail Road as part of an evaluation of how the surface performs over time.

“It’s been used by other agencies with all indications of success,” DuPage’s chief highway engineer Chris Snyder tells the Naperville Sun. “DuPage said, ‘we oughta try it on our system, see how it works.’”

The environmentally friendly technique has been used in Cook County, and DuPage officials want to follow suit, the paper reports.

To create a mile of the pavement, 2,000 ground tires are mixed with asphalt. Production costs are slightly higher, averaging $11 more per ton of rubber tire asphalt than regular asphalt, Snyder says.

By overlaying Army Trail Road with both types of asphalt in different sections, officials will be able to observe how the recycled portion holds up and whether it is more rut-resistant as predicted. Snyder says it is expected to last three to five years longer than traditional asphalt, which has a surface life of 10 to 12 years.

The work will be performed by K-Five Construction of Lemont, Ill.

Rubberized asphalt has been used for more than 20 years to resurface highways and city streets in Arizona when pavement surfaces reach their normal life expectancy, according to the Arizona Department of Transportation (ADOT). While it has always helped with the disposal of used tires, the material has recently has been recognized for its reduction of traffic noise.

Rubberized asphalt consists of regular asphalt paving mixed with “crumb rubber” – ground, used tires that would otherwise be discarded or take up space in landfills. Used tires are processed by separating the casings, fabric and steel. The extracted rubber is then pulverized to the consistency of ground coffee. Rubberized asphalt has the benefit of being smoother and quieter. Noise readings have shown the rubberized asphalt generally reduces tire noise by an average of 4 decibels.

According to ADOT, the product displays a number of advantages:
• It does not reflect cracks from the existing pavement;
• It is more durable and skid-resistant than conventional asphalt; and,
• It reduces traffic noise and provides a smooth, quiet ride.

Noise Tests on chip/seal and asphalt rubber pavements in Phoenix showed a decrease of about 10 decibels, or about a 90 percent reduction in noise level. Research shows that reductions in noise levels of 50 percent to 75 percent are commonly attained.

During the 1990s, Phoenix resurfaced more than 200 miles of streets with 450,000 tons of rubberized asphalt, which used about 1.1 million old tires. The city reports that rubberized asphalt applied on a particular road in 1989 has performed without maintenance for 14 years, and it has an estimated life span of up to 18 years.

Weather conditions play a role, as the pavement surface needs to be between 85 degrees and 145 degrees for the material to adhere properly.

ADOT is considered a pioneer in the use of rubberized asphalt in paving projects. More than 4.2 million tons of rubberized asphalt has been used on Arizona highways since 1988, at a cost of some $225 million. Those projects have resulted in the recycling of about 15 million old tires.

A detailed account of Arizona’s experiences can be found by visiting www.azdot.gov/Highways/EEG/QuietRoads/what_is_rubberized_asphalt.asp.

The Illinois paving company is at www.k-five.net.