Evaluation of Open Graded Friction Courses: Construction, Maintenance, and Performance Phase II

SPR No. 725This study investigated multiple factors that influence the performance of open graded friction courses (OGFC) in South Carolina with the ultimate goal of improving the long-term durability and performance of OGFCs. The research included laboratory studies to evaluate the influence of aggregate Los Angeles (LA) Abrasion and breakdown, aggregate gradation, compaction temperature, binder content, and tack coats using performance measures such as porosity, mean texture depth, Cantabro abrasion, indirect tensile strength (ITS), direct shear strength, and a newly developed surface abrasion test. Limited field evaluations were also conducted to assess the in-situ performance of OGFC. The results informed specification changes that the SCDOT had implemented throughout the duration of this study, including the addition of a 9.5 mm nominal maximum aggregate size (NMAS) OGFC mix, adjustment of the gradation of the 12.5 mm NMAS OGFC mix, and tack coat specifications for OGFC. Additional recommendations were also suggested for consideration based on the results of this study