Influence of SBS and asphalt on SBS dispersion and the performance of modified asphalt

• High aromatics and low asphaltenes could improve dispersion of SBS.
• Particle size distribution curve S/B ratio at 30/70 was narrower than others.
• As SBS contents increasing the particle size distribution curve became wide.
• With the range of SBS distribution becoming narrow the viscosity was increased.

Styrene–butadiene–styrene (SBS) modified asphalt (PMA) was prepared by high shear method. Four asphalts with different components and four types of SBS copolymers with different S/B ratio and types were selected in this study. The influences of the asphalt components and SBS structure as well as SBS contents on the particle size distribution of SBS and properties of the SBS modified asphalt were investigated. Fluorescence microscope and the Image-Pro Plus program were chosen to characterize the microstructure and count the particle size distribution of SBS. The results show that the asphalt components, SBS structure and content had significant impacts on the particle size distribution of SBS polymer in asphalt and the performance of SBS modified asphalt. The high aromatics content and the low asphaltenes content could improve the dispersion of SBS in asphalt. When the S/B ratio is 30/70, the particle size distribution curve was the narrowest and the performance of modified asphalt was improved. With the content of SBS increasing, the particle size distribution curve became wide and the softening point of the modified asphalt was increased, while the penetration and the ductility were decreased. The viscosity at 135 °C of modified asphalt was increased with the range of the particle size distribution curves becoming narrow.