When the Rubber Meets the Road: Tires Beef Up Asphalt
July 1, 2004
PICTOU COUNTY, N.S. - Environmental experts in Nova Scotia will have a spring in their step and drivers may feel a bounce to the road come mid-July. That's when the first rubberized road pilot project in the Atlantic provinces kicks off.
BOUNCING ROADS: The Nova Scotia Department of Transportation is involved with the rubberized road pilot project.
PICTOU COUNTY, N.S. – Environmental experts in Nova Scotia will have a spring in their step and drivers may feel a bounce to the road come mid-July. That’s when the first rubberized road pilot project in the Atlantic provinces kicks off.
It all started when the Michelin Tire Company in Pictou County approached the Nova Scotia Department of Transportation and Public Works with an environmentally-friendly idea for the stretch of Granton Rd., already scheduled for road repairs this summer.
“We were going to service this road regardless of whether it was rubberized asphalt or not, so Michelin saw it as an opportunity to be a little innovative with the product that goes down,” said Tom Gouthro, manager of technical services for the Nova Scotia Department of Transportation and Public Works. “We haven’t done anything like this before so we were a little reluctant at the beginning. But we did some homework and realized that there are benefits from it and so we agreed.”
The process of creating a rubberized road includes mixing crumb rubber – essentially granulated rubber particles from auto and light truck tires – with asphalt cement, prior to adding the resulting binder to the aggregates. This is called a wet process, according to the Rubberized Asphalt Concrete Technology Centre, and it is this process that will be used in the Nova Scotia project.
The project is planned for a 3.3-kilometre section of the road that is subject to a high volume of truck traffic.
“We are only about five miles from that section of road and our trucks travel on it all the time,” said David MacDonald, operations manager for King Freight lines.
There has already been some success with rubberized roads throughout the U.S., and Michelin, along with Clemson University, participated in one of these projects at its headquarters in Greenville, S.C., said Norma Nixon, corporate communications manager for Michelin Canada.
“If five per cent of the repaving done annually in the U.S. used rubberized asphalt, it would consume all of the 300 million used tires discarded annually,” said Nixon. “For the Pictou County project, about 6,000 scrap tires will be used.”
If a tire is buried whole in a landfill site, it can float to the surface and break the cap on the landfill and expose once buried waste to the environment. Decreasing the number of tires in landfill sites is environmentally beneficial, according to a paper put out by the Rubber Pavements Association in Tempe, Ariz.
But the environment is just the most obvious benefit; there are other advantages to this technology.
“This idea has potential,” said Dan Davis, of the Nova Scotia Department of Transportation and Public Works. “A rubber component in road surfaces will provide a more durable pavement that resists reflective cracking and rutting, so our road surfaces could be improved greatly.”
Rubberized asphalt also has a higher skid resistance and it has a longer-lasting colour, which makes striping and marking easier for road crews.
Traffic noise reduction may be another benefit. When residents of Sacramento, Calif. were dissatisfied with the use of tall noise barriers to mitigate significant traffic noise, the Sacramento County Department of Environmental Review and Assessment commissioned a study of the effects of rubberized asphalt on reducing traffic noise.
The study found that traffic noise levels decreased by approximately five to seven decibels following the repaving with rubberized asphalt. This finding indicates its use shows promise as an alternative or supplement to other forms of traffic noise reduction.
Rubberized asphalt can be applied in reduced thickness compared to conventional asphalt and this results in a cost savings of as much as $29,700 per lane mile, according to the Rubberized Asphalt Concrete Technology Centre.
The $569,000 contract for the Pictou County roadwork was awarded to S.W. Weeks Construction.
The Department of Transportation and Public Works will pick up this cost but additional costs, including the purchase of the recycled rubber, and bringing in specialized equipment and professional expertise from Clemson University in South Carolina, will be paid for by Michelin.
The Pictou County project is slated for completion by Aug. 31.