Effect of etched Layered double hydroxides on anti ultraviolet aging properties of bitumen

Layered double hydroxides (LDHs) etched by nitric acid was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), zeta potential potentiometer, scanning electron microscopy (SEM) and ultraviolet and visible (UV-Vis) spectrum. TEM suggests that etching treatment causes the formation of some defects on the surface of etched LDHs and XPS shows that some hydroxyl groups are eliminated from the surface of LDHs after etching. The zeta potential of LDHs is enhanced from 12.02 mV to 17.21 mV for etched LDHs, which suggests etching treatment of LDHs can enlarge repulsion force between particles of LDHs. SEM confirms that the etching treatment is helpful to reduce the agglomeration of LDHs. UV-Vis curves indicates that the absorption UV capacity of LDHs is significantly improved by etching treatment. Moreover, the impact of etching treatment on the physical properties and dynamic rheological characteristics of LDHs modified bitumen during the process of aging was thoroughly investigated. Investigation results indicate that the etching treatment of LDHs is favorable for improving the ductility of LDHs modified bitumen. And the etched LDHs modified bitumen shows the smaller variations of physical properties and dynamic rheological properties as well as structural indexes after UV aging than those of LDHs modified bitumen, revealing that etched LDHs is more beneficial to enhance the anti-ultraviolet aging properties of bitumen since the improvement of dispersity and UV shielding capability of LDHs after etching.