Evaluation of the effect of binder type and layer thickness on the performnce of open graded friction courses

To improve the long-term durability and functionality of open graded friction courses (OGFC), the Florida Department of Transportation (FDOT) investigated the use of a highly modified asphalt binder and increased thickness using Accelerated Pavement Testing (APT). A total of six test sections with combinations of two modified binder types (PG 76–22 and PG 82–22) and three lift thicknesses of 0.75 (19.05 mm), 1.25 (31.75 mm) and 2 (50.8) inches were constructed at FDOT’s APT facility. Accelerated loading was performed using a Heavy Vehicle Simulator (HVS) to evaluate the relative rutting performance of the test sections. Supplementary field and laboratory tests to evaluate tensile strength, Cantabro loss, field permeability, surface characteristics, and asphalt binder properties were also conducted. Test results indicated that the use of PG 82–22 polymer modified asphalt (PMA) binder may be beneficial to improve long-term durability of the OGFC. Thicker layers of OGFC were found to have considerably lower durability. It is recommended that the use of a highly modified PMA asphalt binder in OGFC layers be considered when raveling and other durability issues are of concern.