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 CC 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.