Interaction between asphalt and mineral fillers and its correlation to mastics’ viscoelasticity

The property of asphalt mastics consisting of asphalt binder and mineral fillers significantly affects the performance of asphalt mixture and also results in several forms of distresses in pavements. In addition to the materials properties, the interfacial interaction between asphalt binder and mineral fillers has a significant impact on the performance of asphalt mastics. This research aims to study the influence factors of interaction between asphalt binder and mineral fillers, and explore its relationship to viscoelasticity of asphalt mastics. Two kinds of asphalt binders, four kinds of mineral fillers and five filler/asphalt ratios were selected to prepare forty asphalt mastic samples. The interaction degree between asphalt binder and mineral fillers was characterised by a new introduced parameter C. The influence factors including the properties of asphalt and fillers were analysed. The correlations between interaction and mastics’ rheological properties at different temperatures were statistically investigated. Results show that increasing the polar components ratio of asphalt binder, raising the specific surface area of fillers, making the size composition of fillers finer or increasing temperature all can increase the interaction degree between asphalt binder and mineral fillers. Linear relationship was considered to be an optimum type to represent the correlation between interaction degree and viscoelastic properties of asphalt mastic at temperatures between 15°C and 65°C. There was a very significant correlation between dynamic shear modulus/rutting factor/fatigue factor and C value when the temperature was between 25°C and 45°C. This kind of correlation weakened at 15°C and 55°C, but still significant. The phase angle of asphalt mastic has a significant correlation with interaction parameter C value only at 25°C and 35°C.