Preparation and Evaluation of Performance and Mechanism of Gallic Acid-Rubber Powder-Microalgae bio-oil/Styrene Block Copolymers Composite Modified Asphalt

To address the problems of rubber powder (RP) modified asphalt, such as segregation, high viscosity, and poor storage stability at high temperatures, this study reports the preparation of gallic acid/ rubber powder (GA/RP) modifier by grafting gallic acid (GA) on the surface of RP. GA/RP was, in turn, composited with SBS modified asphalt (SBS-MA) under the synergistic effect of microalgae bio-oil (MB) to produce GA/MBRP/SBS composite modified asphalt (GA/MBRP/SBS-CMA). In the test results of asphalt's three indicators, the optimum dose of GA surface-grafted RP was attained at a GA-to-RP ratio of 20 g:1.5 g. The dynamic shear rheometer (DSR) test revealed that the storage modulus (G') and loss modulus (G") of GA/MBRP/SBS-3 modified asphalt were 48.0% and 51.5% higher than those of the RP/SBS-CMA (64 degrees C and 10 Hz), respectively. Segregation tests showed that the difference between the upper and lower softening points of modified asphalt was reduced, indicating that the phase separation of GA/MBRP/SBS-CMA improved. Fluorescence microscope (FM) tests revealed that RP and SBS were fully swollen and formed a well-developed network structure responsible for the enhanced mechanical properties of GA/MBCR/SBS-CMA under high-temperature conditions. Compared to the RP/SBS-CMA, GA/MBRP/SBS-CMA exhibited better storage stability and strong resistance to segregation. These results indicate that GA/MBRP/SBS-CMA has practical application value in the construction industry due to its more potent mechanical properties and storage stability.