According to Donald Matthews of Pavement Recycling Systems, Inc. in California, asphalt has always been recyclable. In fact, according to him, it is the #3 recycled product in the world after water.
Proof of the success of asphalt recycling in Canada can in found in Perth County, Ontario, about a 2-hour drive west of Toronto. In the spring, the director of public works for Perth County, John McClelland, received Asphalt Recycling and Reclaiming Association’s (ARRA’s) annual Charles R. Valentine Award for Excellence in Cold Recycling.
The main reason for the recognition of Perth County by the ARRA was due to the County’s commitment to recycling of asphalt. According to municipal estimates, since 1991 Perth County has saved approximately $25,000 per kilometre by choosing to rehabilitate its 440 km of roadway using recycled asphalt.
“Perth County has one of North America’s longest running in-place asphalt recycling programs and has been performing CIR (cold in-place recycling) on its roads successfully since 1991,” said Nicholas Cifelli, a technical services manager specializing in pavement products at The Miller Group, prior to presenting McClelland with his award. “Approximately 90% of the county’s road network has been remediated using CIR, averaging 15-20 km per year, and a total capital spend of $4 million.”
There are a number of innovations in asphalt recycling that are currently used in North America including eco-friendly manufacturing and eco-friendly ingredients.
Cold-in-place (CIR) recycling of asphalt has been around in Canada for some time. CIR is a pavement rehabilitation technique that reduces the life cycle cost of the pavement structure by reusing the existing asphalt pavement. This process generally uses 100% Reclaimed Asphalt Pavement (RAP) mixed with a new binder which may be either emulsion or foamed asphalt cement.
CIR may be considered wherever cracking, permanent deformation and/or loss of integrity in the existing bituminous pavement occur. Structurally sound and well-drained pavements are the most suitable candidates.
When the pavement is distorted, corrective operations may be required prior to the CIR process which include road profiling and/or the addition of corrective aggregate. The addition of a corrective aggregate may be required to modify the gradation or to improve the strength of the recycled material when rutting, shoving, and flushing exists.
CIR is considered the most effective process to mitigate reflective cracking in a cold climate and is widely utilized as a cost effective rehabilitation alternative to traditional reconstruction methods due to its comparatively low cost, higher life cycle and ease of construction.
The asphalt industry considers eco-friendly ingredients to include recycled material. For example, Canadian Road Builders Inc. offers a mix called Vegecol that is made entirely from renewable, plant-based material and can be used on major roads as well as for walking and biking paths. As an added benefit, there are no petrochemical ingredients to contaminate run off water.
Besides CIR, there is also hot-in-place recycling on asphalt that involves the recycling of the top layer of asphalt that includes scraping, mixing and then repaving in one continuous chain. Basically, this process consists of four steps: (1) softening of the asphalt pavement surface with heat; (2) scarification and/or mechanical removal of the surface material; (3) mixing of the material with recycling agent, asphalt binder, or new mix; and (4) laydown and paving of the recycled mix on the pavement surface.
The primary purpose of hot in-place recycling is to correct surface distresses not caused by structural inadequacy, such as raveling, cracks, ruts and holes, and shoves and bumps. It may be performed as a single-pass operation or a multiple-pass operation.
The City of Hamilton used hot-in-place asphalt recycling on a portion of the Red Valley Parkway in the summer. In an interview with the Hamilton Spectator, Gord McGuire, Hamilton’s new director of engineering services, stated that repaving the Red Valley Parkway would cost around $6.75 million. Using hot-in-place recycling would safe time and money.
Hurdles to Implementation of Innovations
With the potential savings in time and money (and possibility of an award) through asphalt recycling, it may be surprising that asphalt recycling is not commonplace across Canada. However, a recent report issued by TARBA, an association of road builders that promote the betterment of the road building industry in the City of Toronto and other municipalities, there are some municipalities not recycling asphalt.
The TARBA report, entitled Leaders and Laggards, provides information compiled by independent research that examines the aggregate recycling policies and practices of a sample of large municipalities. The study also ranked the municipalities based on whether they are “Leaders” or “Laggards” in supporting aggregate recycling. The results follow.
The TARBA report concludes that Ontario’s largest municipalities have a long way to go before they can fully realize the benefits of increased use of recycled aggregate materials. The report notes that the current policies and practices across Ontario municipalities vary. Based on the survey data provided by the municipalities, some municipalities emerge as “Leaders” and others as “Laggards” in this area. The report states that even in the municipalities identified as “Leaders” there is room for continued growth.
There is much that municipalities can learn from one another in this respect, sharing best practices and working together to increase the use of recycled aggregate materials in order to realize more of the associated benefits for their communities.
The report holds the Government of Ontario as an good example of a public tendering agency that accepts and encourages aggregates recycling. About 20% of the aggregates used in Ministry of Transportation (MTO) projects – whether for granular base and fills or new hot mix asphalt – are recycled asphalt and concrete materials.
Finally, the report concludes that increasing the use of recycled aggregate materials in road infrastructure projects represents an opportunity to reduce their impact on the environment, decrease costs, and find efficiencies.