Comparing Fine Aggregate Angularity with Aggregate and Hot-Mix Asphalt Performance Tests

Abstract

The fine aggregate angularity (FAA) was determined for 13 fine aggregate sources (angular and round) and eight aggregate blends. AASHTO T304 Methods A, B, and C as well as the Kansas Department of Transportation test procedure KT-50 were used to determine the FAA value. The direct shear test and the compacted aggregate resistance (CAR) test were also conducted to provide a more performance-based aggregate parameter for comparison. Eight different aggregate blends were used to construct eight different fine-graded 12.5-mm Superpave® hot-mix asphalt (HMA) mixtures with similar gradation and volumetric properties. The HMA mixtures were tested in the asphalt pavement analyzer and repeated shear and frequency sweep at constant height test modes of the Superpave shear tester to evaluate their respective permanent deformation properties. Results indicate that for the fine aggregate sources used in the study, the FAA and CAR values correlated well, as did the CAR values with the angle of internal friction calculated from the direct shear tests. By a comparison of the FAA value of the aggregate blends with published criteria of the HMA permanent deformation tests, the Superpave-recommended FAA value of 45 was validated. Results of the HMA mixture testing and FAA comparison also allowed for the recommendation of a pass–fail CAR value for use in Superpave mix design.