Effect of segregation tendency of aggregates on macroscopic properties of asphalt mixture based on composite geometric characteristics

Abstract

The composite geometric characteristics of coarse aggregates can effectively evaluate the combined effect of geometric morphology and size distribution in particle system. The composite angularity indices can be used to evaluate the segregation tendency of aggregates. To analyze the effect of aggregate segregation on the macroscopic properties of asphalt mixtures on the microscopic level, five segregated asphalt mixtures were designed, and the macroscopic properties were measured by a set series of tests encompassing Superpave gyratory compactor test, immersion Hamburg wheel-tracking test and indirect tensile test. The results show that the heavier the coarse aggregate segregation, the higher composite geometric indices, which are closely related to themacroscopic properties of segregated asphaltmixture. The composite angularity and textures play a greater role in the contact properties of the particle system and the macroscopic properties of the asphalt mixture than the composite shape. The large composite geometric indices imply strong contact among coarse aggregate, impeding the process of compaction. The low segregated asphalt mixture has most stable skeleton-bonding structure formed by the interaction of the geometric morphology and asphalt binder, and its resistance to rutting deformation, water stability and low-temperature crack resistance are best.