Experimental characterization of the compatibility between bitumen and fillers from a perspective of bitumen components and filler characteristics

In the composite system of asphalt mixtures, asphalt mastic, which is composed of fillers and bitumen, plays a key role. To achieve precise control and prediction of the performance of asphalt mastics, the effects of filler characteristics and bitumen components on the performance of mastics were investigated in this study. Five bitumen sources and five filler types were selected to prepare twenty-five kinds of asphalt mastics, and the macro and micro tests were conducted on the mastics. The grey relational analysis was applied to quantify the relationship between raw material characteristics and mastic performances. The results indicate that the properties of asphalt mastics exhibit a high correlation with the raw material characteristics. The resin content of bitumen is suggested to be one of the most influential properties for the fatigue performance of asphalt mastics. The penetrations, resins and aromatics contents of bitumen exhibit a specific contribution to the low-temperature performance of mastics. Among all filler characteristics, D10 (the particle diameter when the pass rate of the filler is 10%) and P20 (the content of fillers with a diameter of less than 0.02 mm) are recommended as two critical indicators for selecting fillers because these two parameters exhibit a higher correlation than other similar parameters. The filler characteristics such as particle size and specific surface area significantly affect the fatigue performance of asphalt mastics because the effect of fillers on the fatigue performance of mastics is the competitive mechanism between physical hardening and particle-filling enhancement. This study provides a reference for achieving the better performance of asphalt mastics by controlling bitumen sources and filler characteristics.