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The objective of this paper was to find new modifier to improve the aging resistance and low temperature cracking resistance of asphalt. To investigate the aging resistance of modified asphalt binders, mesoporous nano-silica（doping Ti~（4＋）） was used as a asphalt modifier. Some physical properties including penetration, ductility, and softening point of asphalt were analyzed with RTFO（Rotating thin film oven） aging and ultraviolet aging. Moreover, the performances of high and low temperature of modified asphalt binders with pressure aging were tested by dynamic shear rheometer（DSR） test and bending beam rheometer（BBR） test. These results showed that the penetration decreased, low temperature ductility, and softening point increased when adding mesoporous nano-silica to base asphalt. After ultraviolet radiation aging, the penetration loss and ductility loss of modified asphalt decreased than that of original asphalt, the increase of softening point was also significantly reduced than that of base asphalt. Furthermore, The test results of DSR and BBR showed that the G＊sinδ and creep modulus‘s＇ of pressure aged asphalt decreased, but the creep rate ‘m＇ increased. It can be concluded that the aging resistance and cracking resistance of modified asphalt are improved by adding mesoporous nano-silica, especially the doping of Ti~（4＋） could improve the aging resistance obviously.

The moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating tests.Pressure aging vessel（PAV） test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of binder.Penetration grade tests including penetration test,soften point test,and ductility test as well as SuperpaveTM performance grade tests including viscosity test,dynamic shear rheometer test,and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of binder.Fourier transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of binder.The results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt binder.The modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.

We applied LDHs to modify the bitumen by melt blending, and studied the viscoelasticity of LDHs modifi ed bitumen by means of dynamic shear rheometer（DSR）. The creep test was used to evaluate the viscoelastic behavior. The experimental results indicated that, due to the addition of the LDHs, the viscoelastic properties of modifi ed bitumen were superior to those of pristine bitumen. Therefore, the LDHs would be an alternative to modifi ers used in the bitumen to improve the UV-aging resistance during the service of asphalt pavement.

When the filler-bitumen ratio of asphalt mortar changes, its adhesion and viscoelasticity will also change, as well as its mechanical performances, such as fatigue durability at normal temperature and low-temperature ductility. Thus, the filler-bitumen ratio directly affects the asphalt mortar's performance. This paper tested the physical indexes of the No. 70 matrix asphalt mortar modified by additive Sasobit (SB) and Sasowam (SW) through dynamic shear rheometer and bending beam rheometer under different temperature conditions, and comprehensively analyzed the high-temperature anti-rutting and fatigue performance, low-temperature crack resistance performance, and ductility of asphalt mortar. The results show that ore powder not only can increase the anti-rutting factor but also can increase the aging resistance of asphalt. SB has better performances than SW at high temperatures. As for the filler-bitumen ratio of asphalt mortar with additive SB, the recommended value is between 0.8 and 1.2, and the value may be a little larger for that with SW.

Dynamic rheological properties of asphalt modified by Supramolecular UV resistant material—layered double hydroxides（LDHs） was studied by means of the dynamic shear rheometer（DSR） test.Two typical base asphalts were chosen and modified by 2 different LDHs contents.DSR tests were performed on the original samples,samples after exposed to outdoor and samples after the artificial accelerated UV aging tests respectively to analyze the rheological properties.It is found that when the LDHs content is between 3wt% and 5wt% of asphalt weight,the high temperature performance and fatigue resistant property of the modified asphalt become better,the UV aging resistance properties are improved.

A composite rejuvenator was used for the rejuvenation of aged asphalt in comparison with the common rejuvenator. The effects of the rejuvenators on the performance and microstructure of the aged asphalt were investigated by physical properties tests, dynamic shear rheometer and atomic force microscopy. The results indicate that the physical and rheological properties of the aged asphalt are restored more significantly by the composite rejuvenator than the common rejuvenator, which can be ascribed to the effective recovery of microstmcture of the aged asphalt. The composite rejuvenator has the potential to be used for the rejuvenation of severely aged asphalt since it can restore the colloidal structure of the aged asphalt effectively through composition regulation and chemical reactions between the composite rejuvenator and asphaltenes.

To test self healing capability of asphalt binders,three asphalt specimens（pure asphalt,modified asphalt and aged asphalt） were prepared.Every specimen was tested by dynamic shear rheometer（DSR）.The temperature sweeps result indicates that both aging and SBS modifying influence the self healing capability of asphalt binder.The fatigue-heal-fatigue test was introduced to study the self healing capability of asphalt in its serving periods.Furthermore,three different periods（0.5 h,1 h,3 h） were set up to study the influence of rest time on fatigue time.It is concluded that longer rest time,less load will delay the appearance of cracks and extend the service life of asphalt binders.

Modified asphalt binders were prepared by adding conductive materials, graphite and carbon fiber. The rotation thin film oven test （RTFOT） and pressure age vessel test （PAV） were conducted to simulate the binder aging in the field. Rheological properties of graphite and carbon fiber modified asphalt binder were investigated by the empirically rheological properties （penetration and softening point） and the dynamic shear rheometer （DSR） test. Results show that physical properties of asphalt binder change with conductive material mixed. DSR tests present that the values of complex modulus increase while phase angles decrease under a proper amount of graphite and carbon fiber. Rutting parameters point out that graphite can improve the rutting resistance of asphalts. Rheological parameters can be used to assess aging.

The microstructure and dynamic rheological characteristics of asphalt containing different polymer modifiers （crumb rubber, styrene-butadiene-styrene and crumb rubber mix with styrene- butadiene-styrene） at mid and high service temperature levels were investigated by using scanning electron microscopy（SEM）, dynamic shear rheometer（DSR） and repeat creep test. The main objective of the investigation was to rank the modifiers based on their effect on performance characteristics of asphalt under service conditions. To evaluate the effect of different modifiers on the viscoelastic response of asphalt, the temperature and frequency dependences of the dynamic viscoelastic properties were compared. The mid-temperature fatigue resistance and high-temperature rutting resistance of three polymer modified asphalts were evaluated to predict their field performance in roads. Based on the current results, an improved rutting factor was proposed to determine the rutting resistance of asphalt pavements. In addition, the viscous stiffness （Gv）, defined as the reciprocal of viscous compliance, was used to evaluate the high-temperature deformation resistance of asphalt mixtures. The experimental results indicate that the asphalt containing crumb rubber only shows superior performance at mid and high service temperatures in all three modified asphalt binders due to the action of the crumb rubber.

A dynamic shear rheometer （DSR） setup, with a modified test geometry specifically developed for the mortar, was used to conduct time and frequency domain tests. The mortar was composed of a pure bitumen, filler and fine fractions of sand. In the test setup two mounting procedures were compared and the one that delivers better test result repeatability was selected. Test results obtained from frequency domain tests were used to construct a master curve using time-temperature superposition principle （TTS）. Time domain material functions were obtained from the master curve by using frequency-time domain inter-conversion. In this process a series of Kelvin-Voigt element were used. Using material parameters obtained from frequency domain results, creep-recovery tests in time domain were simulated using a Matlab program. Results show a very good agreement with experimentally obtained creep-recovery data.