DEVELOPMENT OF LARGE STONE ASPHALT MIXTURES IN LOUISIANA

摘要

Large stone asphalt mixtures (LSAM) are hot mix asphalt (HMA) mixtures that contain top aggregate sizes of greater than 25-mm (1-in). LSAM has the potential to provide stronger stone-on-stone contacts than mixes with smaller top aggregate sizes, thus forms a stronger rut-resistance. The paper presents the findings of a laboratory study of LSAM carried out at the Louisiana Transportation Research Center (LTRC). Two types of large stone asphalt mixtures: an open-graded LSAM and a dense-graded LSAM were designed based on both volumetric properties and engineering performance tests. These two mixtures were compared to their corresponding conventionai Louisiana Type 508 drainable base mix and Type 5A base mix respectively, through laboratory performance tests. The performance test results reported in this paper included indirect tensile test at 25°C, axial creep test at 40°C, Asphalt Pavement Analyzer (APA) rut test at 60°C, and Superpave simple shear frequency sweep at constant height (FSCH) at 60°C. The results from this laboratory study indicated that the open-graded LSAM exhibited better rut and strip resistance than the conventional Type 508 drainable mix. The dense-graded LSAM and Type 5A base mix exhibited similar performance from laboratory tests. Further field verification to the results of this lab study was recommended.