Evaluation of ultraviolet aging resistance of bitumen containing different organic layered double hydroxides

Layered double hydroxides (LDHs) have been alternatively employed to improve the ultraviolet (UV) aging resistance of bitumen due to their high UV reflectance, but LDHs particles cannot be dispersed into bitumen uniformly and stably since their poor compatibility with bitumen. Therefore, the problem of poor compatibility must be solved before its application. Generally, organic modification can change the surface characteristics of inorganic particle and then improve the compatibility. The objectives of this work are to evaluate the effect of prepared various organic LDHs on the anti-UV aging property of bitumen and then determine an optimal organic LDHs for bitumen modification. For these purposes, three organic anions, sodium dodecyl benzenesulfonate (SDBS), sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSO), were used as organic modifiers to prepare organic LDHs (OCLDHs), then the storage stability and anti-UV aging of OCLDHs modified bitumen were investigated. Experimental results show the organic modification can suppress the separation phenomenon of OCLDHs modified bitumen during the high temperature storage, indicating the compatibility and stability of the mixture is ameliorated. Compared with LDHs modified bitumen, OCLDHs modified bitumens show lower aging degree during UV exposure, which indicates that OCLDHs exhibit better effect in enhancing the anti-UV aging performance of bitumen. FTIR analysis indicates that OCLDHs effectively retard the formations of oxygen-containing functional groups and aromatic structure of bitumen. Furthermore, SDBS is a preferable modifier for the preparation of organic LDHs due to the most effective improvement in compatibility with bitumen and UV aging resistance of bitumen as compared with SDS and SDSO.