Synthesis of Hydroxyapatite-Polydopamine-Rubber powder modifier via in-situ growth strategy for the designing of HAP-PDA-RP/SBS modified asphalt

Based on the impact resistance of hydroxyapatite (HAP) and the adhesion of polydopamine (PDA), in situ biomimetic mineralization strategy was used to grow HAP-PDA coatings on the surface of rubber powder (RP) to prepare HAP-PDA-RP, which was in turn applied as a modifier to prepare styrene–butadienestyrene (SBS) modified asphalt (SBS-MA). XRD, Raman and XRF analyses confirmed the successful synthesis of HAP monomers. EDS and SEM showed that HAP-PDA is successfully attached to the surface of RP while FM test revealed a clear cross-linked network structure in HAP-PDA-RP modified SBS-MA (HAP-PDA-RP/SBS-MA). DSR test results indicated that at 46 °C, the storage modulus and loss modulus of 15%HAP-PDA-RP/SBS-MA were 27.9% and 24.5% higher than those of 10%RP/SBS-MA respectively. MSCR tests showed that compared to the strain of SBS-MA, the strain of 15%HAP-PDA-RP/SBS-MA was decreased by 78.5% and 65.0% at 0.1 kPa and 3.2 kPa stress levels, respectively. This study provided a facile and convenient strategy for the preparation of HAP-PDA-RP/SBS-MA with significantly superior mechanical and thermal properties for practical applications in construction and road industries.