 Where the roof meets the road
<<Sounds of sifting shingles>> Narrator Says: At first it may seem like the two have nothing in common. But asphalt shingles contain many of the same materials as the hot-mix asphalt King County uses to pave roads. This unique relationship has given rise to another unlikely relationship within King County. As part of a goal to eliminate all resource waste by 2030, the King County Solid Waste Division and Road Services Division have teamed up to test out a program that would recycle asphalt shingles from old roofs, and use them in the mix of new asphalt pavement. The effort is called ‘Linkup’, and works to expand markets for selected recyclable and re-usable materials. In this case, the shingles are used in the pavement, and therefore don’t end up in a landfill. The Road Services Division recently used some recycled asphalt shingles to pave this two-mile stretch of road near Enumclaw, along Southeast 416th Street. This stretch sees a good mix of car and truck traffic, and is therefore a good cross-section for the demonstration study of the use of this material. On top of driving down the cost of paving, use of recycled shingles for this type of work takes advantage of a material that would otherwise have gone to waste in a landfill. WSDOT Bituminous Materials Engineer Joe DeVol says: An opportunity, obviously there's plenty of recycled asphalt shingles. I think that was King County's plan or interest in this project is to try to reduce the amount of asphalt shingles going into the landfill. I think as any municipality, everybody has to be looking for ways to reduce the waste that we do or reuse the materials that we have. That goes along to the sustainability issues that we're all faced with. We're not going to be able to continue to use new materials on any and every highway project. So any time we can pull materials out of landfill that have a benefit or a quality going into our construction projects or any kind of construction-related materials, we need to look at that opportunity to pull those materials out and reuse them as much as possible.>> <<Sounds of paving>> Narrator Says: Every year in King County, about 17,000 tons of asphalt shingles are generated by re-roofing projects, with each home generating between one and three tons. The program, on top of reducing waste, can generate about two barrels of oil per ton of recycled shingles. King County Senior Geotechnical Engineer Kevin Kelsey says: What we're working with in the recycled asphalt shingles is, we're trying to get the benefit of the oil out of the recycled shingles. And there's also some mineral aggregates in the shingles. And so what we wanted to do was understand how much oil is going to be added into the virgin asphalt mix. And based on that and based on national studies we came up with a certain percentage of RAS, or recycled asphalt shingles to add to the mix. And we ended up having a virgin asphalt mix with 15% of recycled asphalt pavement, which is RAP, and 3% RAS for a total of about 18% of recycled products in the mix. Narrator Says: King County is not the first to experiment with recycled asphalt shingles. Minnesota and other states have taken the lead allowing the county to learn from their practices and see if the program can be viable in the future. WSDOT Bituminous Materials Engineer Joe DeVol says: From the demonstration project, we've had that opportunity as I mentioned to see what other states are doing across the country as well as bring it back here and see how it will work in our pavements. Obviously we want to see if we can still get the performance when we're using asphalt shingles or reused materials from building construction or even from highway construction. So this just kind of fits into the typical realm of technology development that we're always busy or working to enhance or develop. Narrator Says: This county effort has been in the works for the last two years and has included Washington State Department of Transportation as a key partner. It’s part of ‘Linkup’, a Solid Waste Division program that works to expand markets for recyclable and reusable materials through partnerships with businesses, public agencies and other organizations. King County Senior Geotechnical Engineer Kevin Kelsey says: What I liked from the start of this is that I thought it could work. I like the idea of using that asphalt binder from that roofing. I like the idea of pulling that stuff out of Solid Waste and putting it into the Road Services. At Road Services we're very environmentally conscious. We don't want to decrease the structural integrity of this road whatsoever. But if we can even make it stronger we're all for it. This product has the potential. Narrator Says: Early in 2010, the county will share the initial study results in a published report, the Road Services Division will continue to monitor the stretch of road for the next three years before deciding about the regular use of recycled asphalt shingles in county roads.
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