Discarded roofing material gets second life in new applications
Nobody likes to see waste, especially not when there appears to be so many options for the reuse of asphalt shingles. Shredded asphalt shingles can be used in gravel road dust suppression, hot patch road repairs, as an admixture to asphalt and cement, as shredded material mixed with aggregate suitable for building up roads or multi-use nature trails, or as fuel for cement kilns and electricity generation.
Yet about 1.25 million tonnes of asphalt-based roofing materials are discarded annually in Canada. In the United States, the number is between six and nine million tonnes, according to Athena Sustainable Materials Institute's briefing paper, Enhanced Recovery of Roofing Materials. Almost all of it is dumped in municipal and private construction and demolition landfills across North America. And these possibilities are not just hypothetical. To a limited extent, asphalt shingles across North America are already being reused in many of these applications.
"It's not a new idea. Asphalt shingles are being recovered to some degree in Nova Scotia, and it's being done in several locations in the United States," says Randal Goodfellow of Goodfellow Agricola Consultants Inc.
The company prepared a report on behalf of the Canadian Construction Innovation Council and Natural Resources Canada, titled Enhancing the Recovery of End-of-Life Roofing Materials: An Implementation Plan. A key driver in developing this plan was a multi-stakeholder workshop held in Toronto on Feb. 19 and 20, 2007, where experts from across Canada and the United States converged to look at options for environmentally sound recycling of asphalt roofing materials.
"We wanted to bring the shingle manufactures together with the environmentalists, landfill operators, the contractors, policymakers and say look, "˜How do we move forward and so that nobody is terribly disadvantaged?'" Goodfellow explains. One of the core messages to come out of this conference was that any regulation around end-of-life shingles could not disadvantage any of the stakeholders. If, for example, additional requirements for asphalt shingle disposal drive up the front-end cost of shingle manufacturing, the roofing market may shift towards the use of metal roofs, which of course would meet with strong opposition by asphalt shingle manufacturers.
But it is hard to envision regulations that won't negatively impact one party while benefiting another. Free markets don't always work in the interests of the public good, and the drivers to enhancing end-of-life roofing materials recovery are compelling. According to the implementation plan, the top three drivers are: the large and growing volume of construction waste currently being dumped, the potential benefits in reducing greenhouse gas emissions, and the increasingly limited availability of landfill space.
In built-up areas of the United States, where landfill costs have skyrocketed over the decades, simple market forces have already spawned some level of asphalt shingle reuse. Parts of New England, according to waste management consultant Dan Krivit of Dan Krivit and Associates Inc., have a 15-year history of tear-off shingle recycling.
"There are pockets elsewhere in the country, but as far as the single most prevalent region, it's New England," he says. The end-use for New England's shingles is primarily in aggregate. In other places such as Nova Scotia, progressive waste management practices have been an outcome of government incentives and regulations. Even though Nova Scotia hasn't banned asphalt shingles from either its private or municipal landfills, it has created incentives that compensate construction and demolition processors for diverting materials from its municipal landfills. This is but one component in an elaborate waste management strategy, which includes a ban on dumping food wastes along with a dozen other materials from Nova Scotia's municipal landfills. As a result, that province has the lowest per-capita disposal rate in the country"”some 44 per cent lower than the Canadian average and about 60 per cent below Alberta's average of 960 kg per person.
"Shingles are still dumped into our private landfills," says Bob Kenney, solid waste resource analyst of Nova Scotia's Department of Environment and Labour. "But the municipal landfills operate within a diversion credit program we have in place." This program is geared to business sector waste, construction and demolition waste, as well as residential waste. For every tonne the municipality diverts from landfill, it gets about $20"“$22 from the provincial Resource Recovery Fund. Shredded end-of-life asphalt shingles in Nova Scotia are currently being used in landfill road amendment and dust control as landfill cover (although this use is waning as more valuable uses replace it). It is mixed with gravel for use on multi-use trails.
"These trails are not only for people walking and biking, but for ATVs as well," Kenney explains. The composition of the topping mixture is 75 per cent shredded shingles and 25 per cent gravel. In some cases, 50-50 per cent mixtures are used. But the most innovative and promising end-use has been pioneered by a Halifax-based construction and demolition materials processor, Halifax C&D Recycling Ltd., which shreds the shingles and screens them into grit and flake. It sells the sand to a local asphalt paving company and gives the flake"”the fibre material covered in asphalt"”to Lafarge as an alternative fuel for its Nova Scotia cement kiln.
"Asphalt shingles have a very high Btu value," says Gerry Meade, executive director of the Canadian Construction Innovation Council. "They could also be used in the generation of electricity and other forms of power. But those options have not been pursued aggressively."
Meade notes that the general public is easily alarmed by the word "incineration""”and particularly when the burning involves waste products. This is why the February asphalt shingle recycling conference included discussion of the development of a wide range of other uses. In Alberta, for example, Lafarge in Calgary and Edmonton both reuse shredded asphalt shingles as an admixture in its asphalt and concrete mixes.
Brent Middleton, manufacturing and operations manager with Lafarge, says the company has been doing this for about five years in Alberta and is currently accepting as much asphalt shingle as it needs for this purpose. "In using it in asphaltic concrete mixes, we've found it improves the durability and long-term performance of our products," he says.
Less impressive, however, is the source. Lafarge gets its shingle material as a waste product from an asphalt shingle manufacturing line, which is a relatively common practice across North America.
"We've looked at using old shingles from houses, but there are some issues with contaminants, including nails and even asbestos, depending on the age of the shingles," Middleton says. To get a place where old shingles see greater recovery and recycling will require building a bridge to span the economic advantages of simply dumping the material. Currently in Alberta and most of Canada, the cost to dump shingles is a fraction of the costs of recycling when all is factored in: collecting the materials, separating and sorting them, removing nails, investing into the equipment for shredding, and then transporting the product to appropriate markets. In turn, these markets need to also make investments in specialized incineration equipment or adapt current production methods to accommodate the reprocessed waste stream.
Even in Lafarge's Alberta operations, the cement manufacturer is paid a tipping fee to take away the shingles. And even that fee, according to Middleton, doesn't necessarily cover Lafarge's capital and ongoing costs to process what are actually new and uncontaminated asphalt shingles from a manufacturing line"”no sorting, removing of nails, and re-transporting required. Also considering the potential mountains of tear-off shingles, some end-users such as road builders have raised red flags. They worry that highways"”which are precisely engineered structures"”will become the dumping ground for rubber, glass, scrap concrete, asphalt, and other materials society no longer has any use for.
"What is needed to move this forward is to do the necessary pilot studies and demonstration projects to show that alternatives to landfilling are technically, economically, and environmentally viable," Meade says. But he adds that ultimately, if the fee to dump asphalt shingles in landfills remains much lower than the cost of recovering that material, they will go into landfill. And even if one municipality says it will no longer accept asphalt materials, in the absence of unilateral regulations, the shingles will go into somebody else's landfill. So without some form of government intervention, it is difficult to see much progress being made in the next three or four years most stakeholders give this initiative to sort out how best to deal with end-of-life asphalt shingles.
Given how unpopular governmental meddling in economic matters is these days, no one is holding their breath for an impressive outcome. But government intervention doesn't always need to be intrusive, Krivit maintains.
"Regulation is just one of many initiatives. There are many voluntary approaches that can be used by the government short of mandates, regulations, and/or market subsidies," he says. "Yes, government intervention will be needed," he adds "but it will have to be a combination of government intervention as well as private entrepreneurs and companies stepping forward."
As for most new markets to be developed, it sometimes takes this kind of private and public partnership to provide the spark for business development, job growth, and environmental protection. "If we want to find the means to the end, which may be diverting 100 per cent of tear-off shingles from landfills, then it may have to be a 5- or 10-year vision."