Experimental and theoretical characterization of the engineering behavior of bitumen mixed with mineral filler

The dynamic shear rheometer (DSR) and the bending beam rheometer (BBR) were used to characterize the rheological properties of bitumen mixed with mineral filler that is smaller than 75 μm in size. The study focuses on using a rheology-based model to assess the effect of two distinctly different fillers, quartz and calcite, on the engineering behavior of the bitumen-mineral filler mastic. Four conventionally different bitumens were selected to assess the filler effect. By mathematically modeling the rheological response, predicting the rheological behavior of mastics becomes simpler and more efficient in approach. The rheological properties of bitumen-mineral filler mastics are characterized using the time-temperature superposition principle after data obtained from DSR and BBR are converted to the same unit. The stiffening effects of the filler are relatively small at short loading times or low temperatures, but are larger at higher temperatures or long loading times. This stiffening effect is found to be bitumen dependent as well as filler dependent. The validity of a micromechanical model is confirmed in this study. The Nielsen model was selected since it employs rheological parameters that could explain the filler effect. The micromechanical model shows good agreement with testing data at the filler volume fraction up to 22%.