| Asphalt is widely used in the pavement constructionbecause of excellent roadperformance. But asphalt will be aging in the course of using it as the influence ofnatural environment factors such as ultraviolet radiation, heat and oxygen, whichlead to asphalt pavement service life shortens greatly. In order to extend the servicelife of asphalt pavement, layered double hydroxide LDHs and ultraviolet absorbenthave been used to modify the UV resistant ability of asphalt. However, single LDHsor ultraviolet absorbent has limited function to improve ultraviolet aging propertiesof asphalt. For further enhancing the anti-aging performance of asphalt, UV absorberwere inserted and assembled into LDHs layers, a kind of UV-absorber intercalatedLDHs material which has not only ultraviolet absorbing ability but also ultravioletshielding ability was prepared in this article. Physical properties and aging propertiesof ultraviolet absorbent intercalated LDHs and ultraviolet absorbent compositeLDHs were respectively studied.Firstly, the salicylic acid intercalated LDHs was prepared by anion exchangemethod and2-hydroxy-4-methoxy benzophenone-5-sulfonic acid (UV-284)intercalated LDHs was prepared by roast reduction process, and its structures werecharacterized. Then the UV absorber (UV-531, UV-284) complexed LDHs, salicylicacid intercalated LDHs and UV-284intercalated LDHs were used to modify asphalt.The physical properties, thermal aging properties and UV-aging properties of UVabsorber complex LDHs modified asphalt and UV absorber intercalated LDHsmodified asphalt were investigated respectively. Finally a kind of UV absorberwhich can both complex and intercalate with LDHs was selected and used to preparemodified asphalt, the effects of intercalation and complex way to modified asphaltwere compared. The main conclusions are as follows:(1) X-ray diffraction spectrum (XRD), infrared spectroscopy (IR) andscanning electron microscopy (SEM) analysis showed that anionic UV absorber(salicylic acid, UV-284) corresponding anion has been introduced into the LDHslayersand formed the intercalated structure; Ultraviolet-visible spectroscopy (UV-Vis) demonstated that the intercalated LDHs not only has excellent UV shieldingperformance, but also has a strong UV absorption capacity.(2) The performance of asphalt have been significantly improved with theaddition of UV absorbers composite LDHs. Compared to single LDHs, thepenetration and ductility of asphalt increased, softening point and viscosity changeslittle; After thermal oxidation (TFOT) aging, the viscosity aging index (VAI) and thesoftening point increment (SPI) of asphalt have been reduced so that thermal agingproperties were improve. SPI and VAI of modified asphalt were significantlylowered after ultraviolet (UV) aging, UV aging performance were improved.(3) The performance of asphalt have been significantly improved with theaddition of UV absorbers intercalated LDHs. Compared to single LDHs, modifiedbitumen has higher softening point and the viscosity, has slightly higher penetrationand ductility; After TFOT aging, SPI and VAI of bitumen reduced, its thermal agingperformance improved. SPI and VAI of asphalt significantly reduced after UV aging,the UV aging performance improved significantly.(4) Compared to UV-284composite LDHs modified asphalt,UV-284intercalated LDHs modified asphalt has higher softening point and the viscosity, butthe penetration and ductility changed little. Intercalated LDHs modified asphalt haslower SPI and VAI than UV-284composite LDHs modified asphalt after TFOTaging.Similarly, after UV aging, the intercalated LDHs modified asphalt has lowerSPI and VAI than UV-284composite LDHs modified asphalt. |
