Comparative Study On Pavement Performance Of Crumb Rubber Modified Asphalt Under Different Cracking Processes

The poor storage stability and high viscosity of ordinary rubber powder modified asphalt restrict its application in engineering.In order to increase the utilization of waste resources such as waste tires,waste plastics and waste cooking oil,the problem of poor storage stability of ordinary rubber powder modified asphalt was solved at the same time.This research group studied the composite modified asphalt of crumb rubber and plastics（CR+PE）,pyrolyzed high content crumb rubber（PHC）modified asphalt and the modified asphalt with pyrolysis crumb rubber in waste cooking oil（WRO）.The performance of the above asphalt is relatively excellent,but to apply the asphalt in practical engineering,the performance of its mixture needs to be tested and studied.In this paper,high temperature pyrolyzed process and waste cooking oil pretreatment process were used to prepare high-content rubber powder modified asphalt（PHC）and desulfurized rubber powder modified asphalt（WRO）,respectively.PE and SBS were used to conduct composite modification of the two kinds of asphalt.Two kinds of asphalt,PHC+PE and WRO+SBS,were obtained.The 70#matrix asphalt,ordinary crumb rubber modified asphalt（CR）,SBS modified asphalt（SBS）and the composite modified asphalt of crumb rubber and plastics（CR+PE）were selected as control group.Under the condition of the optimal asphalt aggregate ratio,asphalt mixtures were papered by AC-13 gradation.The rheological tests were used to determine the high-and-low temperature performance of the asphalt binders.The freeze-thaw test,rutting test,bending creep test and four-point bending fatigue test were used to analyze the water stability,high temperature stability,low temperature performance and fatigue performance,respectively.The results show that the water stability of PHC and WRO mixture is much better than matrix asphalt,CR and SBS.Compared with CR,PHC and WRO mixture is slightly damaged,but its high-temperature stability can reach or even exceed the matrix asphalt mixture.The loss of high-temperature performance can be compensated by the combination of PE and SBS.Modified asphalt with high temperature pyrolyzed process and waste cooking oil pretreatment process could significantly improve the low temperature performance of the mixture,but the low temperature performance of the mixture decreased slightly after the combination of PE and SBS.The fatigue performance of PHC and WRO is much better than that of matrix asphalt,CR and SBS mixture.In this paper,the conventional performance test and the boiling method were used to measure the conventional performance and adhesion of the above asphalt.The rheological index,frequency scanning index and MSCR index of the asphalt were obtained by BBR and DSR,and the correlation between the asphalt performance and the performance of the mixture was analyzed.The results show that the adhesion rating of asphalt used in this test is 5,and the water stability of the mixture is more than 80%.The creep recovery rate R and the non-recoverable creep compliance J_nr obtained from MSCR at 60℃have a significant correlation with the dynamic stability of the mixture,and the correlation coefficients are all above 0.92.The stiffness modulus S,creep rate m and failure strain are all strongly linearly correlated,and correlation coefficients are greater than 0.81 and 0.85,respectively.The coefficient of correlation between the fatigue factor of asphalt cement and the accumulated dissipated energy due to fatigue failure of asphalt mixture is 0.581,and the complex shear modulus of asphalt at 15℃is proportional to the initial stiffness modulus of asphalt mixture.