Mechanical Behavior of Aggregate-Segregated Asphalt Mixtures: Insights from Numerical Simulation and Laboratory Experiment

Abstract

To elucidate the impact of aggregate segregation on the mechanical mechanism of asphalt mixture from both the macro and micro perspectives, the laboratory indirect tensile test and finite element method (FEM) of segregated asphalt mixture were conducted to explore the feasibility of numerical simulation analysis for the mechanical behavior. Meanwhile, the strain characteristics and mechanical strength of segregated asphalt mixtures were analyzed. Moreover, the effects of loading rate and test temperature on the micromechanical behavior and splitting strength were also investigated. The findings reveal that the discrepancy between the simulation results and laboratory result from the indirect tensile tests is within 9.0%, thereby validating the feasibility of finite element (FE) simulation in evaluating the mechanical properties of segregated asphalt mixtures. The strain in the horizontal direction of asphalt mixtures with varying segregation degrees is predominantly tensile, exhibiting a pattern of smaller strains at the edges and larger strains in the center of Marshall specimen. Conversely, in the vertical direction, both edges of the specimen undergo compressive strain, with the central region experiencing tensile strain. Notably, P_1,2 increases with the escalation of aggregate segregation, implying that the uniformity of internal strain E₁₁ in AC-13 asphalt mixtures decreases progressively. Furthermore, the influence of test temperature and loading rate on the internal strain and splitting strength of segregated asphalt mixtures becomes more pronounced in the presence of higher asphalt mortar content. However, under various degrees of aggregate segregation, AC-13 asphalt mixtures exhibit superior cracking resistance compared with OGFC-16 asphalt mixtures.