Numerical Analysis On Meso-Structure Of Asphalt Concrete

Traditional design method for asphalt pavement phenomenologically focuses on the mechanical properties of asphalt concrete materials from a macro perspective, with an assumption that the material is isotropic and homogeneous, which is difficult to reveal the physical mechanism of material deformation and distress. The asphalt mixture is much more complicated. In this paper, asphalt mixture is regarded as a multi-phase composite material system, and its meso-structure is preliminarily simulated in the following three aspects.Firstly, two-dimensional finite elment model is established for the meso-structure of asphalt mixture in the cases of both single aggregate and multiple aggregates, the effects of aggregates with different sizes, shapes, and locations subjected to different loading conditions are studied. Results show that internal stresses of different types of asphalt mixture depend mainly on the material gradation. All of these will provide a basis for asphalt mixture design and aggregates selection. Secondly, surface texture structure has an important role in the pavement performance. The simple model for stripping of asphalt mixture is proposed to locate the stress distributions on the interface between asphalt maxture and an aggregate of different shapes and depths under different loadings. Finally, this paper compares the non-homogeneous Marshall specimens and the homogeneous Marshall specimens through splitting test and numerical simulation, test data demonstrated that non-homogeneity induces anisotrpic properties. For a given segregation, formular for elastic modulus of asphalt mixture Marshall specimen in two directions perpendicular are obtained, which is of reference value for the segregation analysis.