Synthesis of Fe3O4-decorated Mg-Al layered double hydroxides magnetic nanosheets to improve anti-ultraviolet aging and microwave absorption properties used in asphalt materials

Previous studies showed that Mg-Al layered double hydroxides (Mg-Al LDHs) had well anti-ultraviolet (anti-UV) aging properties when used in the asphalt materials, but it cannot contribute to improve the self-healing properties to repair cracks caused by UV aging under the microwave radiation. Fe3O4 has well microwave absorption and based on the layered structure and large surface area of Mg-Al LDHs, the primary objective of this work was to synthesize Fe3O4-decorated Mg-Al layered double hydroxides magnetic nanosheets, to envisage that the added bitumen modifier has both enhanced anti-UV aging properties and microwave absorption properties. Three modifiers were obtained by the adhesion of Fe3O4 magnetic particles on the surface of Mg-Al LDHs nanosheets, and named as LiFi (the mass ratio of LDHs: Fe3O4= 1:1), L2F1 (the mass ratio of LDHs: Fe3O4= 2:1) and L1F2 (the mass ratio of LDHs: Fe3O4= 1:2). Morphology, phase composition, chemical structure, anti-UV aging properties, static magnetic properties and microwave absorption properties of them were detected by different analytical methods. Results demonstrate that all magnetic nanosheets present the ferromagnetic behavior, L2F1 shows the lowest M-s value among three types of magnetic nanosheets, and the value increases from 28.67 emu.g(-1) to 56.78 emu.g(-1) with augmented Fe3O4-LDHs ratio. Additions of Fe3O4 significantly enhance the anti-UV aging properties and microwave absorption properties of Mg-Al LDHs. The maximum R-L value of L1F2 is recorded as more than two times of that of LDHs, and LIF2 shows the best anti-UV aging properties and microwave absorption properties among all magnetic nanosheets. (C) 2019 Elsevier Ltd. All rights reserved.