Effect of salicylic acid intercalated layered double hydroxides on ultraviolet aging properties of bitumen

Salicylic acid intercalated layered double hydroxides (Sa-LDHs) were prepared by ion-exchange method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and ultraviolet and visible (UV–Vis) spectrum were applied to characterize the Sa-LDHs. The increase of basal spacing illustrated in XRD and presence of characteristic peak of salicylic acid observed in FTIR demonstrate that the salicylic acid is favorably intercalated into the interlayers of LDHs. UV–Vis curves of Sa-LDHs reveal the salicylic acid intercalated in LDHs dramatically improves the UV absorption ability, therefore, Sa-LDHs possess both excellent physical reflection and chemical absorption to UV rays. And then the effects of Sa-LDHs and LDHs on UV aging properties of bitumen were investigated. Compared with LDHs modified bitumen after UV aging, Sa-LDHs modified bitumen exhibits smaller changes in physical indexes (softening point and viscosity) and rheological parameters (complex modulus and phase angle), indicating Sa-LDHs can further improve the UV aging resistance of bitumen. The enhanced anti UV aging performance of bitumen mainly attribute to the dramatic improvement in UV absorption ability.