Influence of interfacial zone between asphalt mastic and aggregate on the elastic behavior of asphalt concrete

The interfacial zone between asphalt mastic and aggregate has a significant influence on the macro-mechanical properties and failure mechanisms of asphalt concrete (AC). To investigate the effect of interfacial zone, a 3D two layer built-in micromechanical model is established first, and the interface spring layer is considered to simulate the interfacial zone. Then, the effective elastic modulus and shear modulus of single-phase composite materials with the specific aggregate size are derived. A stepping-scheme is adopted to further obtain the effective elastic properties of multi-phase composite materials. The developed closed-form equations are used to predict the elastic behavior of asphalt concrete, and are able to take into account material characteristic of asphalt mastic and aggregate, the aggregate size and its volume fraction, the interface property, and air voids. Tests on four types of AC are conducted to verify the proposed approach. Finally, the influence of interfacial zone on the elastic behavior of AC is discussed. The developed method can also be used to research other multi-phase particle reinforced composites.