Preparation And Properties Of LDHs Modified Asphalt

Asphalt pavement has become the mainstream road type all over the world due to its good pavemen performance. However, the aging during active time can affect the performance of asphalt, making its life much shorter, the ultraviolet (UV) radiation is an main factor for the aging of asphalt, especially in western China, the intensity of ultraviolet radiation is strong and the time is long, UV aging is a serious problem. Thus, improving the ability of asphalt to resist UV radiation aging is an emergent and valuable work.In this paper, LDHs modified asphalts were prepared by melt blending. The effects of LDHs on physical properties and dynamic rheological properties of the asphalts were investigated. The effect of LDHs on aging properties of bitumen was investigated by the thin film oven test (TFOT) and UV radiation test. The mechanism of LDHs modified asphalt was studied by Ultraviolet visible spectroscopy (UV-vis) and Fourier Transform Infrared spectroscopy (FTIR). The results obtainedare as follows:The softening point and viscosity of bitumen gradually increase, while the ductility and penetration of bitumen decrease with the introduction of LDHs, which was further ehanced with the increasing of LDHs content. Compared with Zn-Al LDHs, the effect of Mg-Al LDHs on physical properties of SK-90#asphalt were more obvious.The rheological properties of asphalt were remarkably affected by LDHs. The modified asphalts exihibited higher complex modulus, lower phase angle and higer rutting factor, which was further ehanced with the increasing of LDHs content. Compared with Zn-Al LDHs, Mg-Al LDHs show better effect in improving rutting resistance of asphalt.LDHs can improve the ability of bitumen to resist TFOT aging and UV aging. The viscosity aging index and the increment in soften point decrease significantly, while the retained penetration increased with increasing LDHs contents. Further more, Zn-Al LDHs are more effective than Mg-Al LDHs for improving the aging resistance of asphalts.FTIR spectrums show that the LDHs can significantly slow down the formation of carbonyl and sulfoxide groups in the aging process, especially in the ultraviolet aging process. Moreover, the formation of carbonyl and sulfoxide groups of Zn-Al-LDHs modified asphalts during aging process were slower than that of Mg-Al-LDHs modified asphalts. UV-visible spectroscopy showed that the LDHs has a strong reflection to ultraviolet light, especially between280nm and400nm wavelength, of which the lowest reflectance is87%, which indicated that multi-layer physical shielding to ultraviolet light was the main factor. In addition, the UV reflectance of Zn-Al LDHs is slightly stronger than that of Mg-Al-LDHs.