One-Step Synthesis of Antioxidant-Intercalated Layered Double Hydroxides to Enhance the Thermal Oxidative and Ultraviolet Aging Resistances of Asphalt

Intercalating antioxidants into layered double hydroxides (LDHs) can effectively enhance the thermal oxidative and ultraviolet (UV) aging resistance of asphalt to extend the service life of asphalt pavement, but the traditional intercalation method involves a tedious process and cannot avoid the influence of LDHs properties on the antiaging effectiveness of antioxidant-intercalated LDHs (OLDHs). This study proposed a facile one-step synthesis method to prepare OLDHs by directly mixing the antioxidants with LDHs precursors. Transmission electron microscopy (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) experiments confirmed that the antioxidant 1222-Na (Antioxidant) was successfully inserted into LDHs with the interlayer distance increased from 0.7 nm to 1.8 nm. Differential scanning calorimetry (DSC) curves, UV-visible spectrophotometry (UV-vis), and free radical trapping experiments indicated that OLDHs had better antiaging properties of asphalt than a single antiaging agent. Dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests reflected that OLDHs enhanced the rutting and cracking resistances of asphalt, but the low-temperature performance was slightly reduced. The results of FT-IR and physical properties tests showed that the asphalt with a 6% content of OLDHs exhibited the best antiaging effect after both UV radiation and pressure aging vessel (PAV). The proposed one-step intercalation method provided valuable insights for future asphalt antiaging research.