Study on rheological properties and regeneration mechanism of pine needle oil recycled asphalt
Aiming at the problems of poor anti-aging performance and high-temperature performance of waste vegetable oil recycled asphalt,a biological regenerant was prepared by using pine needle oil as the base oil and compounding plasticizer,as well as compared with the waste vegetable oil regenerant.The plasticizer used in this study was dioctyl phthalate.The physical properties of asphalt after aging and regeneration were analyzed by the three basic indexes(penetration,softening point and ductility)of asphalt.The test results showed that when 8％pine needle oil and 2％dioctyl phthalate were added into aged asphalt,the physical properties of aged asphalt basically returned to the level of matrix asphalt.Based on the dynamic shear rheometer(DSR)and bending beam rheometer(BBR)tests,the high-temperature and low-temperature rheological properties of recycled asphalt and its secondary aging were evaluated,re-spectively.The results showed that when compared with waste vegetable oil recycled asphalt,the pine needle oil recy-cled asphalt showed better high-and low-temperature rheological properties,and the high-and low-temperature rheo-logical properties of pine needle oil recycled asphalt were better than those of matrix asphalt.This indicated that pine needle oil regenerant could also improve the performance of recycled asphalt by improving the rutting resistance and low-temperature crack resistance of recycled asphalt.In addition,the performance of aged recycled asphalt was also better than that of aged matrix asphalt,indicating that pine needle oil regenerant also could improve the anti-aging per-formance of recycled asphalt by slowing down the aging rate of recycled asphalt and prolonging its service life.The structures of pine needle oil regenerant and asphalt functional groups were determined by Fourier transform infrared spectroscopy,and the regeneration mechanism of pine needle oil on asphalt was analyzed.The analysis results showed that pine needle oil had similar functional groups as those of asphalt,and could supplement the missing light compo-nents in aged asphalt after melting with asphalt,thereby improving the colloidal structure of recycled asphalt and resto-ring its good performance.The main role of dioctyl phthalate as a plasticizer was to reduce the movement resistance at low temperature by lubricating asphalt molecules,thereby improving the low-temperature performance of asphalt.The pine needle oil-based regenerant not only could improve the rheological properties of aged asphalt,but also ensure the durability of recycled asphalt with good secondary aging resistance.
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