Research on the Preparation Process of SBS-Modified Asphalt Using Early Shearing Instead of High-Speed Shearing of Modifier

Abstract

To investigate the effect of pre-shredding as a replacement for high-speed shearing in the preparation process of SBS-modified asphalt, the particle size and mixing time of pre-shredded SBS modifier were studied. Laser confocal microscopy was used to observe the morphological changes and dispersion state of the SBS modifier during the mixing process, and process parameters were determined through rheological performance tests. FTIR tests were conducted on the original asphalt and PAV-aged modified asphalt to assess the impact of the pre-shredding process on the chemical composition and aging resistance of the modified asphalt. The specific conclusions were as follows. During the preparation process of the SBS modifier using low-speed mixing, the morphological changes of the SBS modifier can be summarized as follows: It cycles through edge networking, mesh fiberization, and filamentous granulation, and eventually presents a granular atomization form after multiple cycles. It is recommended that the mixing time be maintained between 30 and 60 min, which results in the microstructure of the modified asphalt consisting of filamentous and point-like combinations. This asphalt exhibited excellent performance in high-temperature rut resistance, fatigue resistance, and low-temperature crack resistance. When the mixing time was too long, the SBS modifier formed small granules in an atomized state, which weakened the strength of the mesh structure and led to a decrease in overall performance. It is recommended that the SBS be shredded into particles sized between 18 and 30 mesh or 30 and 100 mesh. SBS-modified asphalt with SBS particles sized between 18 and 30 mesh exhibited greater hardness in the mesh structure, resulting in better high-temperature rut resistance. SBS-modified asphalt with SBS particles sized between 30 and 100 mesh had better extensibility in the mesh structure, leading to superior performance in medium-temperature fatigue resistance and low-temperature crack resistance. Compared to the conventional process, the pre-shredding process for preparing SBS-modified asphalt improved aging resistance by 10% to 13%. Additionally, SBS-modified asphalt prepared using the pre-shredding process saved 1 to 3 h of processing time compared to the traditional preparation method, reducing energy consumption. Furthermore, the asphalt produced through the new process exhibited better performance, reducing road wear and saving maintenance costs.