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Razing the Roof

Features - Concrete & Asphalt Recycling

Asphalt shingle recycling is gaining momentum as more states are using them in paving materials and other applications.

William Giakoumatos May 13, 2013

About 11 million tons of asphalt shingle waste are generated inthe U.S. each year, according to the U.S. Environmental Protection Agency (EPA). The vast majority of that waste—about 90 percent—is construction scrap from roof installations and tear-offs from roof repairs and replacements. Shingle manufacturing scrap accounts for 9 to 10 percent of this material.

For the construction and demolition industry, roofing waste is no small matter. Roughly 10 percent of construction and demolition debris is asphalt shingle material. Asphalt shingle roof replacement can generate 2 to 5 pounds of scrap material per square foot of roof area, according to the EPA.

Asphalt shingles can be recycled and turned into highways and parking lots. But regulations regarding asphalt shingles recycling vary by state, creating a patchwork regulatory environment that poses challenges for the construction and demolition industry.

Asphalt shingles make up a large percentage of materials used in residential roofing. According to estimates from the Asphalt Roofing Manufacturers Association, Washinton, D.C., asphalt shingles are used on four out of every five homes in the United States. Approximately 12.5 billion square feet of shingles are manufactured each year in the U.S.—enough to cover Washington, D.C., more than four times.

Asphalt shingles are constructed of layers of granular aggregate, asphalt, a base of organic or fiberglass material and a filler/stabilizer, which includes limestone and silica.

More than 60 shingle manufacturing plants generate about 750,000 to 1 million tons of manufacturing shingle scrap each year, according to the EPA.

Construction debris accounts for 36 percent of all landfill waste, according to the EPA. Recycling roofing shingles can significantly reduce this debris.

Roofing contractors also can reduce their disposal fees by recycling used asphalt shingles. The cost of disposing of asphalt shingles at recycling plants is less than landfill disposal fees in most parts of the country. In Mount Airy, Md., for example, the local landfill fee is $40 to $65 per ton. The fee for shingle recycling at one local processing plants is $30 per ton.

Recycling roofing shingles offers environmental benefits, too. Recycling one ton of shingles is equivalent to avoiding the use of one barrel of oil, according to an estimate from shingle manufacturer Owens-Corning, Toledo, Ohio.


From Roofs to Roads

The transportation sector is one area where asphalt shingle waste can be put to good use. The pavers who build, renew and restore America’s highways need high-quality aggregates for paving. Unfortunately, finding those raw materials is a significant challenge in many areas of the United States.

Consider this: The United States currently produces 1.8 million metric tons of aggregate each year. Production is expected to increase to 2.3 billion metric tons by 2020.

Aggregate materials are nonrenewable, however, which raises questions about the stability of our rate of aggregate consumption.

Recycled asphalt shingles could provide relief for road builders. Asphalt shingles are 19 to 36 percent asphalt cement and 20 to 38 percent aggregate—both common highway component materials. Using recycled asphalt shingles as feedstock reduces the costs and environmental impacts of extracting, transporting and processing raw materials.

Building roads that use recycled asphalt shingles in the pavement mix makes sense. After all, asphalt reclamation is already a major part of road repair. In fact, more than 81 percent of all asphalt is recycled back into highway use, making asphalt one of the most recycled materials in the world, according to a Federal Highway Administration report.


Varying State Regulations

As of 2012, at least 13 states had specifications about the use of recycled asphalt shingles. Eight states allow the use of up to 5 percent of manufacturer’s scrap asphalt shingles in hot mix asphalt, including Florida, Georgia, Indiana, Maryland, Michigan, New Jersey, North Carolina and Pennsylvania. Only a handful of states allow tear-off scrap to be used in pavement materials.

Using recycled asphalt shingles (RAS) in road paving has benefits beyond reduced landfill waste. Using RAS in hot mix asphalt increases the stiffness of asphalt, decreases cracking and decreases the susceptibility of the paved area to ruts. Fields studies in Minnesota, North Carolina, Pennsylvania and Vermont all have found benefits of using recycled asphalt shingles in hot mix asphalt.

One study in Vermont field tested remnants from shingle manufacturing plants for processing into recycled road materials. The driving surface was found to have less evidence of potholes than on a nonrecycled surface. Town officials also said the recycled road material was less dusty than natural aggregate.

Facilities that recycle solid waste are responsible for compliance with Federal, state and local environmental regulations and permitting requirements. While no federal law governs asphalt shingle recycling when no asbestos is present, federal law does prohibit the recycling of asbestos-containing shingles. For that reason, most asphalt shingle recycling occurring today is focused on manufacturing scrap rather than on postconsumer scrap.


Recycling Challenges
Despite the advantages of shingle recycling, obstacles remain. Roofers are dependent on the proximity of recycling facilities to make shingle recycling economically feasible. Shipping roofing scrap long distances is costly and can offset the cost savings of recycling instead of landfilling the material.

Another barrier to shingle recycling is the potential for asbestos in tear-off shingle scrap. Because of the risk of asbestos in postconsumer shingle material, many states limit its use in asphalt mixes.

While pavement containing low volumes of shingle materials (5 percent shingles by weight) have performed as well as traditional pavement, performance suffers if shingles are added at a higher percentage, meaning there’s limited demand for recycled asphalt shingles in paving applications. Also, because climate varies from state to state, states mulling the use of recycled shingles in pavements must conduct testing to determine the impact of RSA on asphalt performance. As a result, roll out of shingle recycling programs across all states has been slow.

The inability of some equipment to process shingles is another barrier to shingle recycling, though advances in technology are making it easier to grind, screen and control the dust generated during processing of this material.


Other Potential Uses
Shingles have a high energy content—up to 20,000 British thermal units (Btu) per pound, in some cases. There is already a market for scrap shingles as a fuel supplement in Europe. In the United States, emission regulations limit the use of shingles as a fuel supplement, but some concrete manufacturers use the material as a supplemental fuel source.

Some roofing manufacturers have attempted to use recycled shingles to make new shingles, but results have been mixed.

Roofers also can donate their unused shingles to charitable causes such as Habitat for Humanity, which has put a roofs over the heads of 3 million people worldwide.

Of course, roofing contractors reduce roofing waste by measuring accurately and only purchasing what they need. That helps homeowners, too, by keeping roofing costs down.

 

The author is president of American Custom Contractors, a roofing and home improvement firm operating in northern Virginia, Maryland and Washington, D.C.

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