By James Careless
When it comes to recycling/repurposing asphalt roof shingles and production scraps, the roofing and asphalt industries have put their money where their mouths are by finding ways to use these materials in several asphalt-related applications.
“It is generally accepted that at least 11 million tons of old asphalt shingles are removed from American rooftops annually,” said Martin Grohman, GAF’s Executive Director of Sustainability. “In cooperation with trained roofers who care about the environment, shingle-making firms such as GAF have been encouraging the reclamation of an increasing amount of this waste and diverting it for recycling, rather than sending it to the landfill. Add GAF’s own efforts to ensure that our production scrap is recycled rather than disposed of, and the roofing sector has been making serious progress in finding uses for recycled shingle-related materials.”
How shingles are recycled
The process of recycling asphalt shingles is quite simple. It occurs during the roof replacement process. When the old shingles come off, contractors store them in a separate bin that can be hauled to the recycler, rather than to landfills.
“It is important to separate lumber and metal flashing from the old shingles, because they cannot be recycled together,’ said Grohman. “But nails are no problem: The recycler has powerful magnets that pull them out from the shingles during processing.”
Once at the recycler, the old shingles are ground up into small RAS particles. These particles can then be used in several applications. “There is a trend towards finer grinding of RAS, in some cases using more than one grinding stage, which can produce a higher value product or fractions such as granules only,” Grohman noted. “These advanced grinding processes can open up new markets for recycled materials.”
The good news: “Shingle recycling is available in most major markets in the United States and in some locations in Canada, and new sites continue to open,” according to the Asphalt Roofing Manufacturers Association (ARMA).
Asphalt shingles aren’t the only roof coverings capable of being recycled. PVC roofing membranes can also be reprocessed and reused after removal.
“We ask roofing contractors to cut the membrane into 1-meter strips, which are rolled up and put into cardboard Gaylord boxes for pickup at roofing construction sites,” said Joe Schwetz; Director of Technical Service at Sika Sarnafil; a maker of roofing membranes. “These boxes are brought to recyclers, where the old membranes are ground up and then used to provide backing on the underside of new PVC membranes. Since 2005, we estimate that close to 30 million square feet of old PVC membranes have been recycled and repurposed in this manner.”
What can be done with RAS
There are many ways that RAS can be used. ShingleRecycling.org notes that RAS can also be used in the manufacture of new shingles; using up to 20 percent RAS in new shingles without affecting their quality. RAS can also be burned as fuel. This is a practice that is extensively employed in Europe, but not as widely in the U.S.
Not surprisingly, the major use of RAS is in asphalt pavement applications, where the RAS particles are heated and then mixed with virgin asphalt for road-building and repair.
ShingleRecycling.org breaks down RAS road-related applications into the following categories:
• Hot-mix asphalt
• Cold patch
• Dust control on rural roads
• Temporary roads or driveways
• Aggregate road base
Adding RAS to new hot-mix asphalt can provide some potential benefits. “The ceramics in the shingles provide a source of aggregate, reducing the demand for mined aggregate,” according to ShingleRecycling. org. “Certain properties of asphalt pavement have been shown to improve with the addition of RAS.”
RAS is also a popular ingredient in cold patch. That is the pothole and crack filler that can be applied directly to damaged asphalt pavement without being preheated.
RAS can also improve the surfaces and durability of gravel roads. When ground and then added to gravel, RAS helps to minimize gravel road dust and road noise.
In the same vein, RAS works well as a stand-alone base for temporary roads and driveways. When mixed with recycled asphalt pavement (RAP) and concrete, RAS can serve as a sub-base for construction roads.
Since RAS supply is on the rise, the push is on to find other markets for RAS. Proponents like Martin Grohman are on the lookout for them. “For instance, I am a big believer that RAS is excellent for creating longer-lasting residential asphalt driveways,” he said. “In fact, my own driveway includes RAS for this very reason.”