Evaluation of aging performance of bitumen containing layered double hydroxides intercalated by UV absorbents

This paper investigated the ageing behaviour of bitumen modified with organically modified layered double hydroxides (LDH). Two organo-LDHs (OLDHs) intercalated by different UV absorbents, 2-hydroxybenzoic acid (HBA) and 2-hydroxy-4-methoxybenzo- phenone-5-sulfonic acid, were employed to modify one virgin bitumen using a laboratory high-shear mixer, for comparison purposes, a standard LDH was also included as a binder modifier in the experimental investigation. The rolling thin film oven test and UV exposure test were conducted to simulate the short-term and UV ageing of bitumen, respectively, and then the ageing performance of LDH and OLDH modified bitumens was evaluated by analysing the physical and rheological properties and chemical composition. The results showed that OLDH modified bitumens exhibited improved short-term ageing resistance due to the barrier property of layered OLDH to the penetration of oxygen and loss of light components. With respect to the UV ageing, OLDH modified bitumens were found to be less susceptible to UV radiation because of the improved compatibility with bitumen and UV shield effect of OLDH in comparison with LDH. Chemical composition analysis indicated an increase in the concentration of polar fractions resulting from the generation of oxygen-containing functional groups during ageing, leading to an increase of stiffness of bitumen, the increment of polar fraction of OLDH modified bitumens is smaller than that of LDH modified bitumen, exhibiting less ageing degree.