GAINESVILLE, Fla.-- Old asphalt scraped off roads does not bleed toxins into groundwater and is safe to use as construction fill, according to tests by University of Florida engineers.
The tests were spurred in part by fears that piles of old asphalt at asphalt plants were allowing toxins into the environment, said Tim Townsend, an assistant professor of environmental engineering sciences.
They were also spurred by new federal regulations calling for reducing the amount of old asphalt recycled into new roads, likely raising the need for alternative ways to dispose of it, said Allan Brantley, a recent environmental engineering sciences graduate.
"If I dig a hole and it has water in it, can I use this material as back fill--is it a clean fill?," said Brantley, who conducted the tests as part of his master's thesis on the subject.
When workers grind and mill roads to resurface them, the mixture of asphalt, sand and rock they remove is known as reclaimed asphalt pavement. In Florida, resurfacing generates between 750,000 and 1 million tons of the material each year, with most of it recycled into hot asphalt mix and reapplied to roads or highways, said Gale Page, state flexible pavement materials engineer for the Florida Department of Transportation.
Workers build up piles of the old pavement, and concerns have been raised about rain water filtering through the piles and leaching toxins into groundwater, Page said. Because of these concerns, DOT does not commonly use the material as fill, he said.
For the tests, Brantley and Tim Townsend, an assistant professor of
environmental engineering sciences, used material from two roads and four
piles of asphalt around the state, each containing material from several
nearby roads or surfaces. The roads were Indian Town Road in Palm Beach
County and Interstate 10 in Suwannee County. The asphalt piles were located
in Lake City, Jacksonville, Miami and Tampa.
Contact: Aaron Hoover
University of Florida