| Aging is one of the main factors that lead to the deterioration of the performance of asphalt pavement service.Therefore,it is very important to study the thermal aging mechanism of asphalt.Therefore,it provides an important theoretical basis and basis for the prevention and evaluation of asphalt pavement aging.In this paper,5 kinds of asphalt with different aging levels were tested by the combination of macro and micro tests.The relationship between aging and microstructure,structural changes and macroscopic rheological properties is obtained.First,the preparation of POE/SBS composite modified asphalt,TFOT POE/SBS composite modified asphalt,PAV long-term aging of POE/SBS composite modified asphalt short-term aging of asphalt samples of prepared for routine performance testing(penetration,softening point,low temperature ductility,dynamic viscosity of 60 DEG C),through the data analysis of POE with the best ratio of SBS is 10%:90% the best performance data.At the same time,through the data we found that the needle penetration gradually decreased after aging,and the softening point of POE/SBS composite modified asphalt decreased,and the low temperature ductility at 5 degrees decreased gradually.Secondly,through multiple stress creep recovery test(MSCR)is analyzed with the Burgers model,so that the high temperature performance evaluation indices of asphalt in linear range,elastic recovery rate(R),nonrecoverable creep compliance,and can not be restored creep stress sensitivity index of Jnr-diff,from the data analysis found that adding thermoplastic elastomer POE for high temperature performance of asphalt can improve the effects of the SBS modified asphalt;at the same time with aging,anti rutting performance of asphalt high temperature has been improved.Determination of asphalt at different aging conditions and dynamic shear modulus master curve through frequency scanning test,with complex modulus master curve of asphalt aging increases,which shows the aging degree is bigger,better high temperature stability of asphalt binder,high temperature deformation resistance.With the increase of easy-going test frequency,the complex modulus master curve presents an increasing trend on the whole,but there is a certain difference between the growth rate in the high frequency region and the low frequency region.Then,through the low temperature bending beam rheometer test,analysis of different modifier ratio,aging level of asphalt low temperature rheological performance-low temperature creep stiffness modulus(S,m and Sm(creep rate)stiffness modulus master curve and horizontal coordinates of the area surrounded by the influence of relation)and low temperature performance the agent and the proportion of aging level,found for the low temperature performance of asphalt aging influence,also found that the addition of POE to some extent increase the aging resistance performance of SBS modified asphalt(ratio between 90%-92.5%:10%-7.5%).Finally,through infrared spectroscopy test(IR)analysis of POE/SBS modified asphalt in the aging process of the carbonyl reaction,integral index through the spectrum curves corresponding to functional area(CI)and sulfoxide group index(SI)to quantitative analysis of asphalt in the aging process were divided between the transition from.Data analysis showed that the oxidation reaction is the main reaction of aging asphalt,and the reaction rate with the aging of(non aging,short-term aging and long-term aging)gradually slowed down.The changes of microstructure and chemical composition of POE/SBS modified asphalt with different proportions and aging degree were observed by atomic force microscopy(AFM)and British light microscope.The surface roughness of the quantitative index to characterize the microstructure and chemical composition of asphalt changes.Data show that with the aging level of deepening(not aging(No-aged),short-term aging(TFOT),long-term aging(TFOT+PAV)),roughness value decreases,the light quantity decreased gradually,the analysis results are consistent with macroscopic properties. |
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