Asphalt and filler interaction plays a key role on the performances of asphalt mastics and mixtures, while the asphalt and filler interaction ability is in turn affected by the material characteristics. In order to analyse the effects of material characteristics on asphalt and filler interaction, two kinds of matrix asphalt binders and three kinds of fillers were used to prepare asphalt mastics with different filler volume fractions. The dynamic shear rheological properties of these asphalt mastics were measured. The evaluation index K–B–G ^* was calculated subsequently to analyse the effects of material characteristics on the asphalt and filler interaction ability. The results show that filler volume fraction, filler particle size, SiO₂ content and asphalt components had various levels of effects on the asphalt and filler interaction ability. Variance analysis was then conducted to rank these influencing factors from high to low as: (1) filler particle size, (2) asphaltene and resins content, (3) filler volume fraction, and (4) SiO₂ content.

The asphalt–filler interaction plays a significant role in the performances of asphalt mastics and mixtures, and the asphalt–filler interaction ability could be evaluated by the rheological properties. In this paper, two kinds of matrix asphalt binders and six kinds of fillers were selected to prepare asphalt mastic with different filler volume fractions, and the dynamic shear rheological properties of asphalt mastics were measured and analysed. The filler critical volume fraction which is the transition point from “diluted region” to “concentrated region” for asphalt mastic was defined and determined according to the variation of asphalt mastic’s complex modulus with filler volume fractions. In the “diluted region”, the asphalt–filler interaction plays a dominant role in the increasing of complex modulus. However, the interaction between filler particles plays a dominant role in the “concentrated region”. Then, the complex modulus coefficient ΔG*, the Einstein coefficient K_E and the coefficient K−B−G* were applied to evaluate the asphalt–filler interaction ability in the range of the filler critical volume fraction. It indicated that the three evaluation indices had good consistency for characterising the asphalt–filler interaction ability, but the coefficient K−B−G* had the best sensitivity. So the coefficient K−B−G* can significantly distinguish the interaction ability between asphalt binder and different fillers.

Force chains are deemed as paths to transfer external loading in asphalt mixtures, and its properties difference can reflect the skeleton performances. In this study, the discrete element method (DEM) models of asphalt mixtures were established. Force chains characteristics of dense-suspended and dense-skeleton types asphalt mixtures were compared. Results indicate that force chains number of dense-suspended type asphalt mixtures is much more than that of dense-skeleton type asphalt mixtures. The force chains length shows exponential distribution for all asphalt mixtures. Fine aggregates are involved in transferring external loading, not just the role of filling. Compared with dense-skeleton types asphalt mixtures, dense-suspended type asphalt mixtures have more proportion of short length force chains. Although there are a large number of force chains in dense-suspended type asphalt mixtures, most of them have lower strength, especially for short length force chains. Comparing with the force chains of dense-suspended type asphalt mixtures, the force chains not only have longer length, but also higher strength for dense-skeleton type asphalt mixtures. The external loading is mainly transferred along the vertical direction, and a little loading tends to expand horizontally. The asphalt mixture skeleton structure has a smaller anisotropy degree that is beneficial to transfer external loading.