DNRP > SWD > LinkUp > Asphalt Shingles > Shingles in Paving Demonstration Project

Shingles in Paving Demonstration Project

Shingles in Paving Demo LinkUp is working with the recycling and paving community to champion the development of a hot mix asphalt (HMA) end market for tear-off shingles.

LinkUp is working with the recycling and paving community to champion the development of a hot mix asphalt (HMA) end market for tear-off asphalt shingles by leading a paving trial in the Puget Sound area that incorporates this material.

The project includes seven phases:

1. Conduct stakeholder education and outreach
2. Secure public agency and private industry partnerships
3. Identify and select paving project
4. Develop specifications for use of tear-off shingles in HMA
5. Contract for paving services and material supply
6. Monitor production of RAS, monitor production and installation of HMA, and coordinate sampling and testing
7. Produce report, and share and publish results

Read more about the seven phases (PDF, 138 K) of the Shingles in Paving Demonstration Project.

Advisory Group

An advisory group (PDF, 96 K) made up of industry and agency representatives is helping guide the project by providing input on strategy, project plans, specifications, and more.

Advisory Group Meeting Notes:

• Oct. 16, 2007 (PDF, 55 K)
• Jul. 8, 2008 (PDF, 49 K)
• Nov. 4, 2008 (PDF, 40 K)

RAS Specification Development

LinkUp has developed a specification for recycled asphalt shingles (RAS) (PDF, 1.5 MB) derived from tear-off shingles. The purpose of the specification is to ensure the selected paving contractor receives/produces a clean supply of RAS substantially free of extraneous waste materials and entirely free of whole, intact nails and asbestos-containing material that meets the quality and performance standards needed for incorporation into HMA. To develop the RAS Specification we have worked closely with Washington State Department of Transportation (WSDOT), King County Department of Transportation (KCDOT), project advisory group members and local health and safety regulatory agencies.

RAS Supply and Purchasing

In July 2007, King County Solid Waste Division issued a Request for Information (RFI) to help the project team identify potential recycled asphalt shingles (RAS) suppliers in the region, learn more about them and request RAS product samples. Three companies responded to the RFI. To initiate the process of selecting a shingle processor to supply RAS for the project, KCDOT, with assistance from LinkUp, issued a Request for Quotations (RFQ) (PDF, 217 K) attached RAS Specification (PDF, 1.5 MB) in February 2009 to shingle processors in the central Puget Sound area. The county would have provided this material to the paving contractor selected to complete its South King County overlay project. King County, however, received no response to the RFQ, and so has reconsidered its approach. Instead, it will procure the paving services and materials supply for the demo through a separate, stand-alone contract. KCDOT plans to issue an Invitation to Bid (ITB) for these services by early May 2009.

HMA Specification Development

Two key questions to consider for the HMA specification were the amount of RAS to incorporate and whether or not to use recycled asphalt pavement (RAP). Using samples received in response to the RFI, WSDOT conducted preliminary testing of RAP and RAS, including measuring air voids and asphalt content. The results indicated that adding both RAS and RAP together had the beneficial effect of reducing the amount of air voids in HMA, and WSDOT indicated that it would be preferable to adding only RAS. Based on the results of their tests, and calculations completed by KCDOT staff, the advisory group elected to specify 3 percent for the RAS and 15 percent for the RAP for the HMA mix. The group believes this approach provides an ideal amount of oil replacement and optimizes the air void impacts. A written HMA Specification is in development.

Road Selection

KCDOT, with input from the project advisory group, developed a set of criteria used to select the road section to be paved for the trial. Applying the criteria to several candidate roadways led KCDOT to select SE 416th Street near Enumclaw, WA for the demonstration. The road selection criteria are:

• Existing HMA thickness of at least 4 inches
• Existing condition/level of deterioration
• Consistent and stable subgrade
• No development planned in 10 years that would disturb roadway
• No or limited drainage issue
• Roadway had sufficient amount of truck traffic
• Typical two-lane roadway
• Road length a minimum of 2 miles
• Limited stop-and-go and turning
• Flat and straight roadway

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

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