Evaluation of Factors Influencing the High Temperature Viscoelastic Response of a Fine Aggregate Matrix Using a Modified Multiple Stress Creep Recovery Test

The fine aggregate matrix (FAM), consisting of asphalt binder, mineral filler, fine aggregate, and air voids, plays a major role in the mechanistic response of asphalt mixtures. The behavior of FAM is significantly affected by multiple factors including fine aggregate gradation, asphalt binder type, mineralogical type of the fine aggregate, test temperature, and aging. In this study, three asphalt binders, six fine aggregate gradations, two mineralogical types of fine aggregate, and one field aging effect were considered to prepare FAM samples. A modified multiple stress creep recovery (MSCR) test was used to investigate the high temperature viscoelastic behavior of FAMs by using the torsion bar fixture of a dynamic shear rheometer (DSR), and an appropriate range of creep stress loading in the MSCR test for FAMs was controlled within 1.2 kPa to 25.6 kPa. The results showed that the F-AC13 specimen had the strongest stress sensitivity, especially at the phase of large creep stress. The F-AC20 and F-SUP20 specimens had excellent high temperature viscoelastic performance. The viscoelastic properties of the FAMs were consistent with the properties of their asphalt binder. The FAMs with fine basalt aggregate had better deformation resistance, and the FAMs with fine limestone aggregate had better elastic recovery. The nonrecoverable creep compliance Jnr values of the FAM specimens had more sensitivity to the temperature change, and the percentage recovery %R values increased slightly with increasing temperature. After field aging, the FAM specimens had better deformation resistance and worse elastic recovery. A multifactor analysis of variance (ANOVA) was selected to comprehensively evaluate the significance of these influence factors on the FAM performance. The fine aggregate gradation, asphalt binder, and creep stress had significant effects on the viscoelastic behavior of FAMs. Therefore, improvement of the asphalt binder and fine aggregate gradation can directly enhance the performance of FAMs. The applied creep stress was also a critical condition of the MSCR test for the measurement of FAM performance.