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In September 2009, King County Road Services Division paved a two mile stretch of roadway in South King County (416th Street SE near Enumclaw) to evaluate the use of 3 percent recycled asphalt shingles (RAS) and 15 percent recycled asphalt pavement (RAP) in hot mix asphalt (HMA).

The paving demonstration is the result of a multi-year effort in which LinkUp worked with transportation agency partners and an advisory groupDownload PDF 195 K of technical experts and stakeholders to achieve the following paving demonstration objectives:

  • Reflect the interests and standards of key stakeholders.
  • Evaluate performance of HMA with RAS with a high degree of certainty.
  • Capture objective engineering data to gain wide acceptance of performance test results.

The paving demonstration involved design and development with stakeholders and partners, roadway selection, RAS and HMA specifications development, procurement and contracting for RAS and paving, and paving installation and evaluation.

What we learned

Initial results

Extensive materials engineering tests indicate that using RAS as part of the HMA mix had no negative effect on pavement performance.

Further testing, analysis, and documentation on the long-term performance of this roadway will continue through 2012 to verify the impact of using RAS on public roadways in King County.

For a detailed summary of the background, methodology, findings, and conclusions of the paving demonstration, read the final reportDownload PDF 1.4 MB and appendicesDownload PDF 2.2 MB.

Where the roof meets the road

View a 4-minute video Youtube about this demonstration.
paving demonstration
In September 2009, King County paved a county roadway to test the use of RAS in HMA.

January 2014

The King County Road Services Division has accepted the recommendations made in the final report and, based on those recommendations, are working to implement actions to allow use of HMA containing RAS in the Division’s paving projects.

Final results, which the king county road services division leadership has accepted

The final results mirror results from years one and two, though there are several recommendations to improve the RAS specification. View the reportDownload PDF 1 MB .

Two-year results

Observations and test results at the two-year mark are the same as the one-year results. View the reportDownload PDF 500 K.

One-year results

Observations and test results one-year mark indicate that using RAS as part of the HMA mix has had no negative effect, favorable or detrimental, on pavement performance. View the reportDownload PDF 950 K. View the test section layoutDownload PDF 240 K.

Sharing the results

The results of the study have been shared with a broad group of local stakeholders and others from the Puget Sound region, Oregon, and Canada. LinkUp team members have also presented on the paving demonstration at a variety of regional and national conferences and meetings.

Thank you to everyone involved!

Thank you to all of our partners who have helped to make this project possible.
Special thanks to King County Roads Services Division and Washington State Department of Transportation external link for their commitment and dedication to making the paving demonstration successful.
Thank you also to our advisory groupDownload PDF 195 K, which provided valuable input into the paving demonstration design and development.

For more information

Contact us for more information on the Shingles in Paving Project—Paving Demonstration.

Contact Us

 Call: 206-477-4466

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King County Solid Waste Division mission: Waste Prevention, Resource Recovery, Waste Disposal