King County Using Recycled Shingles in Pavement

A report by King County, Wash., says that a one-year asphalt shingle recycling pilot project involving local and state agencies has proven to be successful. The Shingles in Paving Demonstration Project is touted by the county as the first project in the state of Washington to use recycled asphalt shingles in hot mixed asphalt to pave a public road.

The project comes after a determination that around 23,000 tons of tear-off asphalt shingles from roofing projects in the county go to a landfill.

The King County report says that using recycled asphalt shingles in asphalt paving has the potential to reduce the costs of paving due to the significant amount of oil in the shingles.

In September 2009, a two-mile-long stretch of roadway in the county was overlaid with a 2-inch-thick layer of asphalt paving materials in test sections with and without recycled asphalt shingles.

Staff from King County and the Washington State Department of Transportation recently surveyed the condition of the test sections of the roadway.

The King County Materials Laboratory performed pavement condition surveys by walking the site and documenting any distressed areas. Additional pavement condition surveys were conducted by the Washington State Department of Transportation using a distress data collection van that provided similar results.

An advisory group of representatives from the recycling and paving industries and solid waste, transportation and regulatory agencies was brought together to provide input and help guide the direction of the project.

“We are pleased to report that the pavement with recycled asphalt shingles is performing as well as the test sections with traditional asphalt paving,” says Paulette Norman, Interim Director of the King County Road Services Division. “Recycling asphalt shingles not only benefits the environment, but can have positive economic and job cost impacts as well.”

“This project is important to the paving industry in our state,” says Tom Gaetz with the Washington Asphalt Paving Association. “It is consistent with our commitment to sustainability and green technologies. Some of our members are already using recycled asphalt shingles in paving, and others are eager to learn more.

“The timing of this project couldn’t be better,” adds Gaetz. “Our industry is right now engaged in developing specifications to increase the use of recycled asphalt materials in asphalt paving – all part of our industry’s commitment to deliver the greatest value to our clients and the public.”

“Recycling asphalt shingles into a useful material achieves our goal of zero waste of resources, saves room in landfills and can save agencies money, too,” says Kevin Kiernan, director of the King County Solid Waste Division.
King County will continue to monitor the structural performance of the demonstration pavement through 2012, at which time it will consider recommendations for the continued use of recycled asphalt shingles on public roadways in the county.

In the meantime, LinkUp is continuing to develop specifications and guidance to support the use of recycled asphalt shingles in asphalt paving and coordinate with other regional and national efforts to increase shingle recycling. Information on LinkUp is available at www.kingcounty.gov/linkup.

King County Solid Waste Division is also considering using asphalt paving containing recycled asphalt shingles at one or more of its transfer stations and landfill facilities.

The paving demonstration project is a collaboration between King County Solid Waste Division’s LinkUp Program, King County Road Services Division, the Washington State Department of Transportation and Seattle Public Utilities.

The LinkUp program identified asphalt paving applications as the end use for recycled asphalt shingles with the greatest potential, and set out to facilitate development of local markets for the material.