The interfacial effect of mineral filler to asphalt binder and its influence on asphalt aging behavior

The physicochemical interaction between asphalt binder and mineral filler is investigated in terms of the interaction mechanism and its effect on asphalt aging behaviors. According to the distance of asphalt binder to filler particles surface, the asphalt binder is divided into three different adsorbed films and then separated each other. Subsequently, the chemical and morphological evidences of three asphalt adsorbed films before and after asphalt mastic aging are obtained via Fourier Transform Infrared (FTIR) and Atom Force Microscope (AFM), respectively. The “membrane-like structure” or “moon-like structure” rather than typical “bee-like structure” are observed in the AFM diagrams of different asphalt adsorbed films before mastic aging. In addition, the FTIR spectral images of three asphalt adsorbed films are almost same but the stretching peak at C=C band shows slightly differences. Combining the chemical and structural information, asphalt polar molecules show great prone to be adhered to the filler particle surface compared to non-polar molecules. After asphalt mastic aging, darker color “flake-like” dispersed phase appeared regarding all asphalt adsorbed films. The AFM patterns, however, showed significant differences in terms of their continuous phase. The aging indexes of three asphalt adsorbed films including IC=O and IS=O were within 0.045. Moreover, the physicochemical interaction with filler particles significantly affects the aging behaviors of asphalt adsorbed films that the farther the asphalt binder to filler surface is, the lower the aging index of asphalt adsorbed film is.