Properties Investigation Of A Desulfurized Rubber Rejuvenator Contained Waste Cooking Oil

In order to improve the performance of recycled mixture containing reclaimed asphalt pavement(RAP)in road engineering,it is usually necessary to add the rejuvenators.Common rejuvenators contain a lot of aromatic components,so the aging resistance is poor.And these rejuvenators cannot supplement the polymer degraded in asphalt.This study aims to develop an oil/rubber two-phase dispersion system formed by crumb tire rubber(CTR)and waste cooking oil(WCO)as a rejuvenator.The CTR is cheap and some of the polymer can be replenished after desulfurization of CTR.The application of CTR for the rejuvenation of asphalt material not only have good economic benefits,but also is significant for improving the road performance of recycled pavement and promoting the energy saving,environmental protection and sustainable development of asphalt pavement.In this study,the CTR was mixed with WCO at a ratio of 2:8 and 4:6,then heated the blend at different times,and finally a total of 17 WRO samples was prepared.In this study,the reaction mechanism of CTR and WCO in WRO samples was revealed by the change of solubility,viscosity curve,molecular weight and infrared spectrum of WRO samples with different reaction time and different ratio of rubber and oil(RRO).WRO rejuvenator and two other commercial rejuvenators were added into artificial aged binder to prepare rejuvenated binder for performance comparison.WRO samples with different reaction times and different RRO were added to the aged binder to explore the effect of the WRO rejuvenator preparation process on the performance of the rejuvenard binder.The high and low temperature rheological properties of WRO rejuvenated binder samples were tested by dynamic shear rheometer(DSR)and bending beam rheometer(BBR).The rutting performance of WRO rejuvenated binder samples were tested by multiple stress creep and recovery(MSCR)test.The functional group changes of WRO rejuvenated binder samples and WRO samples were analyzed by Fourier transform infrared spectroscopy(FTIR),and the molecular weight changes of WRO rejuvenated binder samples and WRO samples were tested by gel permeation chromatography(GPC).After the CTR was mixed with the WCO,the CTR particles swelled and the soluble substances in the CTR was dissolved in the WCO.During the process,a series of physical and chemical reactions occurred in the WRO mixture.In the process of desulfurization of CTR in WCO,cross-linking structure of CTR desulfurized and cracked into smaller long-chain structural molecules,continuously releasing polymers such as natural rubber molecules,long-chain saturated hydrocarbons and butadiene.As the heating time increases,the released polymer continued to crack,and the dispersion of the internal molecular size continued to decrease.The viscosity of WRO decreased first,and then the viscosity of WRO increased due to the viscosification effect caused by oxidation of WCO in WRO.When the double bond or single bond of carbon in the WCO is broken,it combined with oxygen,and an oxidation reaction occured to form the carbon-oxygen bond.The newly generated carbon-oxygen bond will also be destroyed at a high temperature,and being in a dynamic equilibrium state.The rejuvenated binder test proved that WRO rejuvenator is an excellent asphalt rejuvenator.The WRO rejuvenator increased the phase angle of the artificial aged binder and reduced the complex shear modulus.In the low temperature circumstance,the asphalt stiffness modulus decreased and the creep rate increased.WRO rejuvenator effectively improved the low temperature performance of reclaimed asphalt while avoiding excessive damage to high temperature performance.At 10% WRO dosage,WRO rejuvenated binder had better high and low temperature performance than neat asphalt.In the WRO mixture,the waste cooking oil contributes the most to the softening of the aged asphalt,and the CTR is more beneficial to the aging resistance of the rejuvenated binder.The larger the RRO,the better the rutting resistance and the aging resistance;the smaller the RRO,the more obvious softening effect and the lower the temperature sensitivity.The addition of the CTR reduced the sulfoxide functional group content of the artificial aged binder.For WRO rejuvenators with RRO of 4:6,the WRO preparation time did not significantly improve the performance of rejuvenated binder.The longer the WRO preparation time,the more sufficient supplement in viscosity,the less damage to the elasticity,the smaller the sulfoxide index and the larger molecular weight of rejuvenated binder.However,as preparation time increased,the aging resistance of the rejuvenated binder became worse.According to the comprehensive test results,the final optimal WRO rejuvenator preparation process is as follows: the CTR and the WCO are mixed in a ratio of 4:6,and then heated and stirred at 260? for 1 h,and finally the WRO rejuvenator is obtained.