Study on the Properties of Titanate Coupling Agent, Modified Heavy Calcium Carbonate, and SBS Composite Modified Asphalt

In this study, heavy calcium carbonate was wet modified using a titanate coupling agent, and fabricated titanate-coupled calcium carbonate and styrene–butadiene–styrene (SBS) were used to prepare composite modified asphalt. Microscopic tests such as scanning electron microscopy and x-ray diffraction showed that the surface wrinkle of the modified calcium carbonate was significantly increased, and the enhanced crystallinity and purity were favorable for its compatibility with asphalt (by segregation). Viscosity (135°C) and three major indicator tests showed that the modified asphalt exhibited good high-temperature performance compared to the original asphalt. Dynamic shear rheological and multistress creep recovery tests indicated that the composite modified asphalt exhibited better viscoelastic properties and resistance to permanent deformation than the pure SBS-modified asphalt. This was attributed to the fact that the modifier caused the SBS to swell sufficiently to form a clearly visible three-dimensional spatial network structure in the asphalt (by fluorescence microscope). This allows the matrix asphalt to form an interlocking phase with the polymer modifier, which in turn significantly enhances the relevant properties of the asphalt, as confirmed by fluorescence microscopy. The results of Fourier infrared spectroscopy suggest that the modifier is only physically miscible with SBS or base asphalt. This study can provide a feasible idea for the practical application of bicarbonate composite modified asphalt, which has greater prospects in construction and highway applications.