Investigation of microstructure, rheological property and self-healing performance of SBS modified bitumen with dynamic disulfide bonds prepared by one-step method

To reduce fossil energy consumption and environmental pollution, in this study, SBS modified bitumen (SMB) with self-healing performance was developed through directly adding aliphatic disulfide (ALD) containing double C C bonds in the melt blending process for enhancing its service life, and sulfur/SBS modified bitumen was also prepared for the comparison of ALD/SMB performance. Fourier transform infrared spectrum analyses indicated that the disulfide bonds of ALD have been successfully introduced between SBS molecular chains . Fluorescence microscopy imageries revealed that the addition of ALD improved the network structure of SMB, and the SMB had a more complete network structure when the dosage of ALD was 0.6%. Compared to SMB, the softening point and ductility of SMB with 0.6% ALD were increased by 4.5 °C and 5.2 cm, respectively. The results of dynamic shear rheometer and bending beam rheometer indicated that ALD improved high- and low-temperature rheological properties of SMB. The fatigue healing test revealed that ALD improved the self-healing performance of SBS modified bitumen. When the dosage of ALD was 0.6%, the healing index of ALD/SMB reached 0.86, while the healing index of SMB and sulfur/SMB were only 0.51 and 0.48. The fracture healing test showed that SBS modified bitumen with 0.6% ALD had a self-healing rate of 66.3%, whereas that of SMB and sulfur/SMB were only 35.8% and 38.2% after 20 h of healing at 50 °C, indicating that ALD significantly enhanced the self-healing performance of SBS modified bitumen.