Influence of colza oil and epoxidized soybean oil on performance of aged SBS modified asphalt

ObjectiveTo investigate the rejuvenation effects and underlying mechanisms of different bio-oil based rejuvenators on aged SBS modified asphalt, a systematic study was conducted on the preparation and performance characterization of rejuvenated SBS modified asphalt.MethodTwo types of bio-oil based rejuvenators, i.e., colza oil residue (CO) and epoxidized soybean oil (ESO), were added to aged SBS modified asphalt at mass fractions of 6%, 8%, and 10% respectively, to prepare rejuvenated samples.The physical and rheological properties of rejuvenated SBS modified asphalt were studied using three major indicators(i.e., penetration, softening point, ductility), dynamic shear rheometer, and bending beam rheometer. Additionally, the fluorescence microscopy and Fourier transform infrared spectroscopy were used to investigate the rejuvenation mechanism of two regenerants from the perspective of SBS phase state and functional group changes.ResultBoth types of bio-oils can significantly improve the penetration, softening point, and ductility of aged SBS modified asphalt. CO exhibits superior softening ability and can effectively enhance penetration and ductility. In addition, both types of bio-oils can restore aged SBS modified asphalt to its unaged level at the dosage of 8%. ESO exhibits a more pronounced phase angle plateau region at high temperatures, demonstrating its ability to repair SBS network structures to a certain extent. At all test temperatures, the stiffness modulus of CO rejuvenated samples are generally lower than those of ESO rejuvenated samples, indicating that CO has a more prominent effect on improving the low-temperature flexibility of aged SBS modified asphalt.ConclusionCO mainly compensates for the loss of light fractions caused by aging, reducing the content of carbonyl and sulfoxide groups through physical dilution, and improving asphalt performance. In contrast, beyond its dilution effect, ESO contains reactive epoxy groups that interact with carboxyl functionalities in the aged asphalt, partially reconstructing the SBS network. The two rejuvenators show distinct rejuvenation mechanisms, characterized respectively as physical softening and chemical restoration.