| Many studies focused on modeling the stiffening effect of mineral filler on asphalt binder. However, the interaction between both constituents was always a challenge to address. This study provides a conceptual model for understanding the mechanism by which the filler stiffens the asphalt mastic. The model hypothesizes that the mastic complex stiffness follows two phases depending on the volume concentration of the filler; a diluted phase and a concentrated phase. In the diluted phase, the stiffening effect of the filler on the binder follows a linear trend where interaction between filler and binder is minimal. On the other hand the effect of the filler departs from the linear trend once its concentration enters the concentrated phase. The deviation from the linear trend indicates that the stiffening effect of the filler starts to depend on the interaction between the filler particles and the asphalt binder. In the proposed model, the effect of mineral filler on asphalt binder complex modulus at given temperature and frequency is characterized using three main model parameters, (a) Initial Stiffening Rate, (b) Terminal stiffening rate, and (c) Critical filler concentration. The results presented in this study provide measurable parameters that can be used to estimate the three main model parameters, which are indicators of the mineral filler interaction with asphalt binder. The proposed model provides an effective tool to determine the role of basic filler physical and chemical properties on the overall stiffness of the mastic. |
