The Municipality of the District of Lunenburg — home of the Bluenose — may soon be known for something else: as a leader in the recycling of asphalt shingles. A pilot project to surface nature trails with a mix of asphalt shingles and aggregate may prove that the ingenuity of this fishing port goes beyond the building of schooners.
The recycling of asphalt shingles provides a tremendous opportunity to utilize an already established material in an innovative way. And in the case of Lunenburg, it provides a cost effective opportunity to complete nature trail projects using a finely finished surface material that is both cheap and plentiful.
Lunenburg pilot project
The Lunenburg project involves the surfacing of nature trails with a mixture of asphalt shingles and aggregate. Partners in the project included local trail groups, industry and the government. The project enabled the utilization of a material in an innovative way while providing a cost effective opportunity to complete nature trail projects using finely finished surface material that is both cheap and plentiful.
The project aims at significantly reducing the quantity of shingles sent to landfill. Shingles are put through a round grinder and then pass over a magnet to removal nails. The ground asphalt is mixed with a small amount of rocky aggregate and spread; it creates a dense, stable surface that is resistant to wear and tear, yet easily graded and repaired if necessary.
Laura Barkhouse, Trails and Open Space Coordinator for the Municipality of the District of Lunenburg, is one of the driving forces behind the trail project. Asked about alternative use of shingles, Barkhouse responded, “Through responsible management and monitoring, this potential resource could become a tremendous asset for recreational trail development.”
In the U.S., ground asphalt shingles have been used successfully in both “hot mix asphalt” and “cold asphalt aggregate mixes” for projects such as dust control on rural roads and temporary road construction.
In the case of hot mix asphalt, the benefits derived from using recycled shingles include a reduced demand for virgin asphalt cement and aggregate and improved properties in the pavement. About a dozen states allow a certain percentage of recycled shingles to be used in HMA pavements.
In the U.S., several states allow the use of ground asphalt shingles to be mixed with the gravel and used to cover rural, unpaved roads. The mixture leads to several improvements in these rural roads, including dust suppression, reduction in the loss of gravel into side ditches, and less road maintenance. These claims were confirmed by a study conducted by the Iowa Department of Transportation.
Lunenburg isn’t the only jurisdiction finding innovative ways to recycle shingles. In Western Canada, Lafarge has developed a process through which the shingle waste can be incorporated into the manufacture of hot mix asphalt. After shredding and sorting according to size, the shingle fragments are added to asphalt reclamation lines.
According to Lafarge, the shingle recycling process offers several benefits including diminished cost of road paving asphalts. A further benefit is that some of the reclaimed shingle components (fibers and aggregates) are used to produce a superior grade of paving mix, featuring better stability, durability, and resistance to rutting and cracking.
There are environmental concerns about possible contaminants found in asphalt shingles. One contaminant, asbestos, is no longer used in the manufacture of asphalt roof shingles. In fact, the incidence of asbestos-containing shingles in roof tear-offs today is extremely low. The total asbestos content of asphalt shingles manufactured in 1963 is only 0.02 percent; in 1977, it dropped to 0.00016 percent.
To ally any concerns about the environmental impacts associated with the incorporation of asphalt shingles into the aggregate used in the trail, the proponents of the Lunenburg pilot project devised a sampling and testing program. The program was devised to confirm that there was no significant impact to surface water quality from runoff from the trail surfacing product.
In Ontario, the Ministry of the Environment recently proposed regulatory amendments to facilitate waste recycling, making it easier for proponents to develop and implement systems needed to recycle while ensuring that the environment is protected. Specifically, the regulation, if promulgated, will allow the use of asphalt shingles in the construction of walkways, roads and parking areas.
The recent announcement is a 180-degree turn from the ministry’s previous position. As late as the spring of 2005, the ministry was issuing cleanup orders for anyone incorporating asphalt shingles into road base. However, faced with a province on the brink of a waste crisis and the scientific evidence, the ministry made the right decision.
John Nicholson, M.Sc., P.Eng., is a consultant based in Toronto, Ontario. Contact John at email@example.com