Influence of Physicochemical Characteristics of Mineral Fillers on the Rheological Performance of Bituminous Mastic

This study investigates the influence of physicochemical characteristics of mineral filler passing 75 µm on the rheological behavior of bituminous mastic. Mastics were prepared with a polymer-modified binder and three different fillers—basalt, granite, and quartzite—in three different volumetric ratios (0.56, 0.60, 0.64). Lime was used as a partial replacement in one set of mastics to study the effect of lime. The physicochemical properties such as morphology, particle size distribution, specific surface area, surface free energy (SFE), and zeta potential of the mineral filler were measured. The Canny edge detection technique was used to extract the roughness metrics of the fillers from the scanning electron microscopy images. Surface-to-surface interparticle distance was also measured through the K-dimensional tree algorithm from the particle size distribution obtained through laser diffraction of filler particles. Among the mastics without lime, mastic with quartzite exhibited the highest stiffness, followed by granite and basalt. Replacement of filler with lime increased the stiffness in the case of basalt, whereas it decreased with granite, indicating intricate physicochemical interactions between lime, fillers, and binder. Regression analysis results underscored the importance of the properties of fillers in determining mastic’s rheological characteristics. Interparticle distance, Rigden voids, pore radius, and SFE are some key parameters found to be influencing the behavior of mastic without lime.