Porous Asphalt Mix Makes Debut on Auburn Campus
BY Christine Hall and Sandy Lender
What’s a great pavement for a natural resource management area? Porous asphalt pavement mix, of course. In June of this year, Allen Asphalt Services Inc., Smiths Station, Alabama, placed the first porous asphalt to be used on Auburn University’s campus at The Edward Via College of Osteopathic Medicine (VCOM). Located in the natural resource management area, the site includes a two-acre pond originally constructed in 1937. The overall project included repair of the pond’s dam and installation of the porous asphalt walking path and two boardwalks.
The area is currently used by Auburn faculty and students for forestry and biology research, nature observation, and as a field teaching lab. Mike Heitzman, Ph.D., assistant director and senior researcher at the National Center for Asphalt Technology (NCAT) at Auburn University, worked with multiple stakeholders to ensure that university researchers and students would be able to use the area as a natural resource.
“The characteristics of porous asphalt made it an excellent choice for this project,” said Heitzman. “Rainwater will drain down through the pavement instead of running off to the side or ponding in low lying areas. This is important for the pond area because this type of drainage will help control storm water and filter out contaminants before they wash into the surrounding environment.”
The overall project in the natural resource area included repair of the two-acre pond’s dam and installation of the porous asphalt walking path and two boardwalks.
Heitzman worked with the Alabama Asphalt Pavement Association to develop a porous mix spec and identify local contractors to work on the project. He shared with AsphaltPro that the mix was a ½-inch nominal maximum aggregate size (NMAS) open graded friction course with PG67-22 binder. Quality control tests by NCAT determined the in-place binder content was 5 percent and the permeability was 0.095 cm/s. The challenge for small, campus projects is convincing a contractor to produce a very small quantity of porous mix. In this case, Allen Asphalt Services stepped up to the plate.
Cindy King of Allen Asphalt Services said they ordered the 180 tons of porous mix from Robinson Paving, Columbus, Georgia. The grading of the path went to Adams Construction, Lafayette, Alabama.
Researchers at NCAT will continue to look for additional opportunities on campus to highlight the benefits of porous asphalt as a pavement of choice to control storm water runoff and improve walking surfaces during rain events.
Portions of this article are reprinted with permission from NCAT Technology News.