Performance evaluation of aged asphalt rejuvenated with various bio-oils based on rheological property index

This study examines the performance of aged asphalt rejuvenated with various bio-oils based on rheological properties and rejuvenation mechanism. Castor oil, gutter oil, soybean oil, straw oil, and vegetable oil were chosen to explore the effects of bio-oils characteristics on the rejuvenated asphalt properties. The contents of each kind of bio-oil were set at 3%, 6%, 9%, and 12%. The high-speed shear apparatus was first used to prepare the aged asphalt rejuvenated with the bio-oils. The temperature sweep (TS) test was used to evaluate the high-temperature permanent deformation resistance of rejuvenated asphalt, and then its high-temperature elastic resilience was measured by using the multiple stress creep recovery (MSCR) test. The rutting and low-temperature crack resistances of aged asphalt rejuvenated with bio-oils were later evaluated by utilizing the frequency sweep (FS) and bending beam rheometer (BBR) tests, respectively. Finally, the functional groups of asphalt before and after regeneration were observed by conducting Fourier transform infrared reflection (FTIR) test, and the relationship between the chemical components of bio-oils and rheological property index of aged asphalt rejuvenated with bio-oils was analyzed by carrying out gas chromatography-mass spectrometry (GC-MS). The results showed that gutter oil and vegetable oil had an apparently adverse influence on G*/sinδ of aged asphalt. Castor oil, soybean oil, and straw oil better improved the recovery rate of aged asphalt, reduced its non-recoverable creep compliance, and effectively enhanced elastic resilience and resistance to its permanent deformation. Gutter oil and vegetable oil made aged asphalt have better low-frequency sensitivity, and most favorable influenced on the crack resistance; The recommended contents of castor oil, gutter oil, soybean oil, straw oil, and vegetable oil were 6.21%∼6.75%, 4.50%∼4.58%, 5.84%∼6.05%, 6.31%∼6.55%, and 5.17%∼5.68%, respectively. The rejuvenation of aged asphalt by adding bio-oils was a physical process; From the perspective of bio-oil composition, it is meaningful to compare and analyze other indexes to scientifically evaluate the extent of rejuvenation.