Synthesis of different antioxidant intercalated layered double hydroxides and their enhancement on aging resistance of SBS modified asphalt mixture

The aging of asphalt mixtures shortens the lifespan of asphalt pavements. Incorporating antioxidant intercalated layered double hydroxides (OLDHs) into asphalt is a viable approach to enhance the resistance of the asphalt binder to aging. However, OLDHs hasn't been optimized and its effectiveness in asphalt mixture is not clear. This study is to synthetize different OLDHs and examine their enhancements on the anti-aging performance of SBS modified asphalt mixture (SMAM). For this purpose, ion-exchange method was employed to intercalate antioxidant 1222, antioxidant 1010, and 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid into the interlayers of Mg/Al-LDHs to prepare different OLDHs (designated as 1010-LDHs, 1222-LDHs, and 3B-LDHs, respectively). The synthesized OLDHs were characterized by crystal phase, chemical structure, micro-morphology, UV-visible spectroscopy and free radical scavenging tests. The three prepared OLDHs were then added to the SBS modified asphalt (SBSMA) and mixtures were prepared with both OLDHs-containing and non-OLDHs-containing asphalts. Aging tests were conducted, and the changes in pavement performance of different mixtures before and after aging were compared to assess the effects of OLDHs on the anti-aging properties of SMAM. Finally, asphalt binders were extracted from different aged mixtures and subjected to relevant tests. The results indicate that all three antioxidants were successfully intercalated into the LDHs while maintaining the layered structure. Additionally, the incorporation of the three OLDHs improved the ultraviolet and thermal-oxidative aging (TO aging) resistances of the SMAM. Among the three, 3B-LDHs demonstrated the best anti-aging enhancement at the same dosage. These findings offer a reference for studying and applying OLDHs to enhance the anti-aging properties of SMAM.