| Anti-aging asphalt, which is modified by supramolecular UV resistant material-LDHs, is a kind of composite material. In order to improve the anti-UV-aging performace of the asphalt, the base asphalt is mixed by LDHs materials with supramolecular structure. LDHs can absorb, shield, prevent and scatter the ultraviolet, which can reduce the irreversible aging effects on asphalts. It can also alleviate hardening and cracking of the asphalt in the service process and enhance the service performance, which can prolong service life of the road. This paper carried forward the outcomes of work in the laboratory, by means of artificial accelerated UV aging test and field sampling.The systematic research on the asphalt modified by the LDHs was also done in this paper, which included the ageing performance, the rheological properties, and the basic pavement performance and the viscoelastic properties of the asphalt. In order to guide the application of the LDHs asphalt in practice project, a theoretical basis and technical support for the promotion and application in practice pavement was also provided in the paper.Firstly, according to the law of solar radiation and the analysis of the correlation between the artificial accelerated ageing test and the wild ageing test, the paper put forward the model parameters of the artificial accelerated UV aging environment. The blue wool standard test was used to compare the effects of asphalt UV aging with different light source.The results showed that the high pressure mercury lamp light source could cause more serious damage and speed up the test and that the correlation between xenon lamp and practical solar radiation is better.Moreover, the test results did not rely on the irradiance intensity, but only depended on the total irradiation. Then, the anti-aging asphalts modified by LDHs were prepared by mass ratio3wt%under optimal conditions with agitator and shearing apparatus in Lab. TG-DSC test illustrated that the LDHs could improve the thermostabilization of asphalt. The effects on the performance of the asphalts by adding LDHs materials was studied by mean of normal tests, the results of which showed that the softening point of aged asphalts rose slightly while the penetration and the ductility were on the decline drastically as well as the moderate enhancement of viscosity. It also showed that LDHs materials could play the significant role on the UV-resistant performance of the asphalt.Secondly, the tests on the microcosmic appearance of the LDHs material and the microstructure of the modified asphalts were carried out by SEM, FTIR and XRD. Researches on the absorption and scattering properties of LDHs particles dispersed in asphalt were based on the Mie theory, in order to study the suitability between the asphalts and the LDHs materials and provide a theoretical basis for preparing different kinds of LDHs asphalts by the excellent combination property, the results showed that the diameter of the LDHs particle was50-150nm, less than the wavelength of UV, and the modified asphalt had the composite structure in which the LDHs material could homogeneously disperse. The analysis of the absorption and scattering properties based on Mie theory could make the optimized selection for both the kinds of the asphalts and the diversity of LDHs materials.Thirdly, the rheological charateristics of the LDHs asphalts were studied by rheology theory. Dynamic Shearing Rheomemter (DSR) was adopted to study the rheological properties of the asphalts samples before and after UV ageing and the results showed that the ability of bearing loads and elastic properties of the asphalts were improved by the LDHs materials. In addition, the complex modulus was on the increase and the phase angle decreased which illustrated that LDHs modified asphalt had the better anti-aging and anti-cracking property at low temperature in comparion with base asphalt. In order to compare the results of UV ageing test between in laboratory and in the practical pavement enviroment, the asphalt paved in NeiMeng in2011was extracted and the asphalts included PJ90and LDHs-PJ90. The viscosity test and DSR test showed that both the aging index (AI) of the LDHs asphalt and rutting factor were smaller than the base asphalt which represents that the LDHs could slower UV ageing process.Finally, the viscoelastic characteristics of LDHs asphalt binders were investigated by the creep test, and proper rheological models were employed to describe the characteristics. Results indicated that the viscoelastic properties of asphalt binders can be altered by LDHs materials. The total deformation of LDHs asphalt binders decreased during loading period and the elastic deformations increased, leading to the reduction of permanent deformation of asphalt binder. First-order Burgers model could be used to describe the viscoelastic characteristics for LDHs asphalt binders, which reveals the elastic and viscous property of asphalt binders can be greatly affected by the LDHs materials. |
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