| This dissertation relies on the Canadian National Natural and Engineering Research Fund of investigation of million tones of Ontario hot mix asphalt(2015-2018).Firstly,The mechanism of physical hardening of asphalt binder and the effect of physical hardening on the low temperature performance grading of common asphalt binder were systematically studied.In order to study the contribution of asphalt characteristics to field non-load-related cracking,rotary evaporator was used to extract the recycled asphalt from broken core samples which soaked in the dichloromethane.Limiting low-temperature performance grading,critical crack tip opening displacement(CTOD)and phase angle parameters of different kinds of asphalt binders were measured by regular bending beam rheometer,extended bending beam rheometer(ExBBR),double edge notch test(DENT)and torsion bar tests.The rationality of different kinds of parameters which used to control the field performance was discussed based on the relationship between actual field pavement cracking investigation and small strain rheological properties,large strain damage properties of extracted asphalt.In order to explore the reasonable indoor simulation method and evaluation index of asphalt binder durability,the rationality of modified pressure aging vessel was further discussed.At the same time,the intrinsic correlation between the limiting temperature difference(?Tc),Glover-Rowe parameter which was currently widely used in United States of America,limiting phase angle temperature and the low temperature performance grade obtained from extended bending beam rheometer was also discussed.The test results confirmed that physical hardening and chemical aging involve the same chemical components.There is a good relationship between phase angle obtained from dynamic shear rheological(DSR)test just after short condition and the creep rate obtained from bending beam rheometer(BBR)after long term condition.Therefore,this parameter could be considered as the control index for the durability of new types asphalt binder in the future.For the reason of high price of conventional low penetration grade straight-run asphalt binder or the refinery plant couldn't refine out specified low-temperature grade straight-run asphalt binder due to the restriction of crude oil source and the construction cost will greatly increased if long distance imports,waste oil such low cost modifiers are favoured by asphalt binder constractors.Among which,waste engine oil refining products not only can solve the problem of waste oil processing and also meets the requirements of conventinal Superpave performance grading,therefore it got widely used in north America and northeastern Canada in past decades.In order to further study the effect of waste engine oil bottom(WEOB)as modifier and recycling agent on the properties of asphalt binder,multiple stress creep and recovery(MSCR)test,linear amplitude sweep(LAS)test,double edge notched tension(DENT)test and extended bending beam rheological(Ex-BBR)test were used to comprehensive evaluate the physical mechanics properties of asphalt binders.Meanwhile,the microscopic morphology of the asphalt system was observed by means of environmental electron microscopy(ESEM)and atomic force microscopy(AFM)to reveal the microscopic mechanism of the change of macroscopic mechanical properties.Finally,the author introduced the implementation of the modified asphalt low temperature grading specification in Ontario,Canada.What's more,the early diseases of asphalt pavement of Citiy of Kingston and the consideration of asphalt binder selection were analysed.Based on the test results,a possible early cracking mechanism was proposed.The difference between the sample used in the asphalt tank and the asphalt binder obtained by extracted by the asphalt mixture after the paving was used for the purpose of quality acceptance.At the same time,the quality acceptance method and criterion of recycled asphalt binder based on loose mixture were put forward. |
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