STIFFNESS PREDICTION OF HOT MIXTURE ASPHALT (HMA) BASED UPON MICROFABRIC DISCRETE ELEMENT MODELING (MDEM)

摘要

Hot Mixture Asphalt (HMA) is a composite material of graded aggregates bound with mastic (asphalt plus aggregate fines). The physical properties and performance of HMA is governed by the properties of aggregate (shape, surface texture, gradation, skeletal structure, modulus, etc.), properties of asphalt binder (grade, complex modulus, relaxation characteristics, cohesion, etc.), and asphalt-aggregate interactions (adhesion, absorption, physio-chemical interactions, etc.). A Microfabric Discrete Element Modeling (MDEM) approach is employed to model the aggregate and mastic to predict HMA stiffness. Based upon uniaxial/biaxial test, the stiffness of the HMA is predicted with the stiffness of the aggregate and mastic. Due to current limitations of 2D modeling, contributions of aggregate interlock as a stiffening mechanism is not fully accounted for and leads to an underestimation of mixture stiffness, as in earlier micromechanical models. The concept of 2-D model calibration is briefly explored, and illustrates the importance of modeling aggregate contacts. Further development, calibration and validation of the micromechanical model are still required, arid will be the subject of future work.