Effect of Antioxidant/CA-LDHs on the Properties of SBS-Modified Bitumen

The cinnamic acid intercalated layered double hydroxides (CA-LDHs) were prepared by anion exchange method and analyzed by X-ray diffractometer (XRD) Fourier transform infrared (FTIR) spectrometer, scanning electron microscopy (SEM), contact angle goniometer, ultraviolet and visible (UV-vis) spectroscopy, and thermogravimetric (TG) analysis system. Then, the CA-LDHs were added to styrene-butadiene-styrene (SBS) modified bitumen together with an antioxidant composed of octadecyl-3-(3,5di-tert-butyl-4-hydroxyphenyl)-propionate (1076) and tris(2,4-di-tert-butylphenyl) phosphite (168) at a mass ratio of 1 : 1. The effects of antioxidant/CA-LDHs on the physical and rheological properties and chemical composition and characteristics of SBS-modified bitumen before and after pressurized aging vessel (PAV) and ultraviolet (UV) aging were investigated. The results revealed that CA was successfully intercalated into the interlayer space of LDHs. Meanwhile, the CA-LDHs performed improved hydrophobicity and UV absorption capacity compared with LDHs, resulting in enhanced compatibility of LDHs with SBS-modified bitumen, and then the antiaging properties of SBS-modified bitumen could be further strengthened, especially the anti-UV aging properties. Moreover, the mixture of antioxidants and CA-LDHs could synergistically improve the SBS-modified bitumen's thermal- and photo-oxidative aging resistance.