Paving the Way for Rubberized Asphalt
By Brenna Kraus
Reprinted with permission from the Torch 2004
We ask a lot of our road surfaces. They carry millions of cars from point A to point B and withstand squealing tires, abrupt stops and the occasional skid marks. They repel water, bend and break with the freeze and thaw cycles and boldly go where no road has gone before.
Now there is a way you – actually, your tires – can give back to our roads.
As it is, tires don’t do a whole lot for anyone once they’ve worn out their usefulness on your car. Over 280 million scrap tires are generated each year in the United States. Of these, over 60 million are unused and being placed in stockpiles.
These “waste” tires are a serious problem in landfills, causing fires to burn year-round and collecting mosquito-breeding water. However, when mixed with tar and fine gravel (called aggregate), recycled tires create rubberized asphalt that has proven to be superior to its predecessor.
Rubberized Asphalt Concrete is highly skid-resistant, quieter and resists damage done by frost heaves and weather cracking. The long-term wear of this asphalt mix has been monitored in Arizona for around a decade of use and the mix is also being used in California and Florida successfully.
Not only is the material successful, it also greatly decreases the amount of tire waste. Depending on the application of the improved asphalt, between 500 and 2,000 scrap tires are used in each lane mile of pavement. This means that in a one-mile section of a four-lane highway, anywhere between 2,000 and 8,000 tires can be used.
This translates into enormous cost-effectiveness; both in the long-term wear of the asphalt (minimizing maintenance) and in eliminating disposal costs of thousands of tires. According to the Rubberized Asphalt Concrete Technology Center in South Carolina, a two-inch-thick rubberized asphalt concrete resurfacing can save as much as $22,000 per lane mile over conventional asphalt.
The benefits of rubberized asphalt caught the attention of Marsha Gordon, the chemist consultant hired by the Sustainable Greater New Bedford Group and hosted by the New Bedford Chamber of Commerce. Attending the meeting, Lee Nason, Facilities Director at UMass Dartmouth, decided to make rubberized asphalt part of UMD’s effort to become more sustainable.
However, Nason’s goals were a bit larger than what has already been done with rubberized asphalt. She decided to tackle local rubber waste as the target for mixing with asphalt and recruited Walaa Mogawer, a faculty member of UMD’s Civil Engineering Department.
Nason reported that the company they will probably be working with is Precix, a New Bedford manufacturer of gaskets and o-rings. Currently, the waste from Precix is being shipped out of the state to be burned, which is costing them money and creating air pollution through transport and burning of the rubber.
Rubberized asphalt creates a market for these local companies to sell their scrap to, rather than pay for disposal – pending the mix with non-tire rubber works. Lot Seventeen at UMass is scheduled for repaving and Nason is going to use the rubberized asphalt mix created by Mogawer.
“We won’t get the wear data that they’ve gotten through road paving,” Nason said, citing weather as the main source of “wear” that parking lots take. “However, we will be able to see how the pavement holds up in comparison with other asphalt put down in the same time frame.”
Putting down the asphalt is a challenge in itself. The mixture is slightly stickier than previous mixes, which makes it more of a hassle for contractors. But that’s not the only thing that makes some wary of jumping on the rubberized asphalt bandwagon.
“I couldn’t find a company in Massachusetts to put it down,” Nason said.
Contractor’s who deal with asphalt gain business from old roads that are in need of repair, so they are hesitant to put down a product that may need less maintenance.
“Will it put some of them out of business? Yes, for some it probably will,” Nason conceded. “The most efficient companies and those that invest in the business earlier will make it.”
Nason found a contractor out of Rhode Island who she says sees the benefit to getting in on dealing with rubberized asphalt earlier than later. However, once the job goes out to bid and contractors see that the project is going ahead, there may be more local interest in getting the contract. After all, a job is a job and there is money to be made.
“This will surely cost more, especially since we’re the first to do this,” Nason said. In speaking with other people in the business, Nason has been quoted an initial cost of about 10-50% higher than a conventional mix. In Arizona, after years of experience, testing and usage of rubberized asphalt, the mix has been laid down at no extra cost.
For Nason and other rubberized asphalt proponents, it’s the long-term investment in lower maintenance costs and greater benefit to local businesses and the environment that provide a considerable payoff.
The sheer economic possibility of the project makes it worthwhile to Nason. She concluded: “Even if it costs 50% more, but lasts twice as long, I’m still ahead of the game.”
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Paved Surfaces Uncensored: Sources: Our Built and Natural Environments, U.S. EPA, 2000; “Highway Statistics 1997,” Federal Highway Administration, U.S. Department of Transportation (tables HM-53, HM-60); and EBN Vol. 5, No. 1, page 13, updated with 1999 Census data |
Last Updated On: 3/17/06
