Pelletized Asphalt for Airfield Damage Repair

Abstract : The use of pelletized asphalt technology to produce airfield-quality hot-mix asphalt (HMA) is evaluated in this study. The pelletization process produces HMA mix components (asphalt cement, fine aggregate, fiber, and polymer) as a pre-manufactured product that could be shipped at ambient temperature to a remote location. There, it can be introduced to locally-produced, heated coarse aggregate in a continuous or batch plant. Two HMA mix types known to provide high shear and rutting resistance were designed and subjected to laboratory tests; one was the stone mastic asphalt (SMA) mix, and the other was a dense-graded airfield (DGA) HMA mix. Laboratory tests using the asphalt pavement analyzer indicated that DGA mixes had better rutting resistance compared to the SMA mixes. Thus, the test sections (one pelletized mix and one conventional HMA mix) at Silver Flag Test Area were built using the DGA mix gradation; the conventional HMA mix served as the experiment control. The test sections were trafficked with 1,500 passes of the F-15E load cart to evaluate the rutting performance of the pelletized asphalt HMA. The pelletized asphalt HMA section showed no rutting; the conventional asphalt experiment control test section exhibited as much as 22 mm of rutting. The study concluded that it is feasible to produce airfield-quality HMA with pelletized asphalt using conventional HMA plants. Conventional equipment was adequate for placing a durable and rut-resistant pelletized HMA. This paper presents results of laboratory and field tests and provides status of field implementation of the technology.