Microstructural Characteristics of Interfacial Zone in Asphalt Mixture Considering the Influence of Aggregates Properties

The interfacial zone between aggregate particles and asphalt mortar presents a significant effect on the strength of an asphalt mixture. In this paper, basalt, limestone, and diabase were selected, and the influence of these aggregates on the mechanical characteristics and microstructures of the interfacial zone was investigated. Nanoindentation was employed to measure the change law of mechanical behavior in the region of the interfacial zone, and corresponding viscoelastic parameters were deduced; microstructural morphology was observed by scanning electron microscopy, and the effect of the mineralogical components on the interfacial zone was analyzed as well. Results show that the mechanical behavior of the interfacial transition zone is complicated. The modulus and hardness of asphalt mortar decrease with the increases in the aggregate surface distance, and then keep stable after the distance is greater than 40 mu m. Both the relaxation time and dissipated energy ratio of the interfacial zone affected by the different aggregate types show a similar change law. These states indicate that aggregate types have little influence on the stress dissipation of asphalt mortar. However, creep compliances that quantify the ability of the deformation resistance show a significant difference; microstructure morphologies of the interfacial zone are affected by aggregates obviously, and micro pores present a different distribution and state in the interfacial zone.