Effects of the morphological characteristics of mineral powder fillers on the rheological properties of asphalt mastics at high and medium temperatures

Abstract

The primary objective of this study was to investigate the feasibility of the dispersion of fillers dispersion as individual particles and evaluate the effects of the morphological characteristics of filler particles on the rheological properties of asphalt mastics at high and medium temperatures. For a given source and filler, three various filler particle sizes produced from different crushers (i.e., a jaw crusher, an impact crusher and a ball grinding mill) were obtained, namely, F1 (P200-R300: passing a 200-mesh and retained by a 300-mesh sieve), F2 (P400-R500) and F3 (P800-R1000). The binary image particle analysis system was employed to acquire the morphological characteristics of filler particles such as form factor, angularity and surface texture. By applying multiple stress creep and recovery (MSCR) tests at high temperature and time sweep (TS) tests at medium temperature, the rheological properties of asphalt mastics prepared with different filler particle sizes were also investigated. Furthermore, the correlations between the morphological characteristics of filler particles and the high/medium-temperature properties of asphalt mastics were studied by grey relational analysis (GRA) method. Results showed that the proposed new approach to sample preparation was demonstrated to be effective in achieving filler particle dispersion. The GRA demonstrated that the rheological properties of asphalt mastics at high and medium temperatures were significantly affected by the morphological characteristics of the filler particles. Percent recovery (R) and fatigue law fitting coefficients (A and B) were more sensitive to porosity, angularity index, average diameter, aspect ratio and fractal dimension but less sensitive to feature roughness, roundness, convexity ratio, density and specific surface area. In terms of non-recoverable creep compliance (Jnr), the sensibility was apparently reversed, with the reference sequence Jnr presenting less susceptibility to porosity, angularity index, average diameter, aspect ratio and fractal dimension. The GRA results can inform engineers regarding the selection of filler particles that produce asphalt mastics with desired performance characteristics, such as specific rutting resistance and fatigue failure.