Study On The High Temperature Performance Of SBS/Crumb Rubber Composite Modifiedasphalt Mixture

Rutting deformation is one of the most important forms of damage of asphaltpavement, which reduces the pavement performance and affects the comfort and safetyof driving, thus high temperature stability is always the most basic road performance ofasphalt pavement. It has become an important issue to improve the high temperatureproperty of asphalt mixture and to prevent and cure rutting deformation in our nation’shigh grade roads construction. And the issue is studied by the SBS/crumb rubbercomposite modified asphalt technology in this paper.The features of various high temperature performance evaluation indexes and testmethods of asphalt binder and asphalt mixture are analyzed at first. Then penetration,softening point,177℃Brookfield rotational viscosity and elastic recovery are chosenas the high temperature performance evaluation indexes of SBS/crumb rubbercomposite modified asphalt binder. And rutting test, immersion rutting test and bendingcreep test are chosen as the research methods of high temperature stability andrheological properties of SBS/crumb rubber composite modified asphalt mixture.The preparation process of SBS/crumb rubber composite modified asphalt whichshows better high temperature performance is selected. Meanwhile, the influence ofSBS dosage, crumb rubber dosage and particle size on the high temperatureperformance of SBS/crumb rubber composite modified asphalt. It shows that the hightemperature performance of modified asphalt enhances significantly with the increase ofcrumb rubber dosage or SBS dosage, and that the high temperature performanceparameters of SBS/crumb rubber composite modified asphalt prepared by20meshcrumb rubber are superior to the one which prepared by40mesh crumb rubber. Theformula of SBS/crumb rubber composite modified asphalt which is chosen finally inthis paper is20mesh crumb rubber/SBS/70#matrix asphalt=16%/2%/82%(massratio).Standard rutting specimen molding method of SBS/crumb rubber compositemodified asphalt mixture is determined. The loose asphalt mixture should undergo ashort-term aging process, and the compaction times should be increased to36. Thenconventional rutting test and immersion rutting test of SBS/crumb rubber compositemodified asphalt mixture of different gradation (AR-AC-13, AR-AC-13S, RAC-13and AC-13) are conducted under different conditions. The results show that gap gradationdoes not have an advantage over continuous gradation in conventional rutting test, butits resistance to rutting is significantly better than the latter under the comprehensiveeffect of water and heat, so it is recommended that SBS/crumb rubber compositemodified asphalt mixture should adopt skeleton-dense gap gradation. Adding cement toSBS/crumb rubber composite modified asphalt mixture not only improves its resistanceto water damage but also ensures its lasting resistance to rutting in case water exists.The ability of resisting to permanent deformation of SBS/crumb rubber compositemodified asphalt mixture is absolutely comparable to that of SBS modified asphaltmixture under extreme external conditions like high temperature (70℃) or heavy load(1.05MPa).Bending creep test parameters and Burgers model viscoelastic parameters alsoindicate that SBS/crumb rubber composite modified asphalt mixture has a goodresistance to deformation, and reveal the internal cause from the perspective of materialrheology.