If you have driven south into Branson on Highway 65 lately, you may not have noticed you were driving over asphalt manufactured with ground tire rubber (GTR). Yet one company in Missouri is paving the way for more widespread use of old tires in constructing better roads, parking lots, and athletic tracks.
Terry Rainey, the chief operating officer of Modified Asphalt Solutions explains: "The biggest challenge that we have faced is acceptance and education on using GTR as an alternative asphalt modifier. Early experiments with rubber asphalt ended with mixed results, and many state transportation departments still remember those days and are reluctant to try it again."
Missouri's acceptance of GTR is growing, however, since the Missouri Department of Transportation financed testing of the material at the National Center for Asphalt Technology in Auburn, AL. "We were very pleased that MODOT chose our material to be tested side-by-side with another asphalt binder using Styrene Butadiene Styrene," says Terry enthusiastically. "With all other factors being equal, the GTR modified section is not only outperforming the SBS pavement, but is currently one of the top performing sections of track at NCAT."
Most people would not think of a paving company as a model green business, but Modified Asphalt Solutions is benefitting the environment in many ways. Tests show GTR modified asphalt has a much longer life cycle than regular asphalt, and reduces the amount of required ongoing maintenance. This means reductions in paving material, fuel used to maintain highways, and emissions from stalled traffic around road projects.
"It has also been tested and proven that by using GTR in the asphalt binder, the road is much smoother and quieter. Test results show that a smoother road decreases resistance on an automobile's tires and actually will decrease fuel consumption," says Terry.
"Of course there is another obvious environmental advantage to our asphalt. It gets a lot of tires out of landfills and makes good use of them for society," says Terry.
Missouri generates approximately 5 million used tires annually. Scrap tires pose an environmental problem, as well as health risks, because they are not biodegradable and they tend to float to the top of landfills, where they prove to be fertile breeding ground for mosquitoes. Fortunately, more than 75% of scrap tires are recycled or used for fuel or other applications. According to the Environmental Protection Agency, 12 million tires are used to manufacture asphalt each year in the United States.
Modified Asphalt Solutions also produces a permeable pavement for new construction projects that can help areas improve water quality.
"The permeable asphalt that our company manufactures acts as a large filter and the stormwater runs through the pavement instead of rolling off and into a storm drain or sewer system," says Terry. "If enough states, cities and counties started using more porous asphalt like ours, it would help in replenishing the badly depleted aquifers and assist with the overburdened wastewater treatment plants."
Porous asphalt can help capture and filter contaminants like oil from cars and trucks, help decrease urban heating, allow tree roots to breathe and reduce the magnitude and frequency of flash flooding.
Terry only sees growth for Modified Asphalt Solutions, as well as the environmental benefits that it will bring.
"We see a very bright future for our company as long as there are cars using rubber tires that get thrown away. We are producing a competitive, longer lasting pavement, and in these tough economic times every agency is looking to make every dollar stretch further. We hope to grow as a company and become part of the long term solution to the extensive environmental challenges facing this country."
This story was featured in the August 2010 newsletter
- Leah Christian, Missouri Environmental Assistance Center