Effect of Organically Modified Hydrotalcite on UV Aging Resistance and Pavement Performance of SMA-13 Asphalt Mixture

To address the UV aging deterioration of asphalt pavement layers, Mg-Al hydrotalcite (AC-03) was organically surface-modified using stearic acid and titanate coupling agent TM-201, respectively, yielding two modified hydrotalcite products designated JC-03 and TM-03. The chemical structure, micromorphology, thermal stability, and UV shielding performance of the as-prepared samples were characterized via Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The optimal dosages of the two modifiers were determined by activation index and contact angle measurements. Subsequently, the modified hydrotalcites were externally incorporated into SMA-13 asphalt mixtures through a dry mixing process, and their effects on the pavement performance and UV aging resistance of the mixtures were systematically evaluated. The results indicate that JC-03 prepared with 3 wt% stearic acid achieves the optimal comprehensive modification effect. Compared with the neat SBS asphalt mixture, the incorporation of JC-03 enhances the dynamic stability and moisture stability of the mixture, and effectively suppresses the attenuation of high-temperature rutting resistance, low-temperature cracking resistance and moisture stability induced by UV aging. TM-03 also provides some modification benefit, but its overall performance is inferior to that of JC-03. This study provides an experimental basis and a technical reference for the design of anti-aging materials for asphalt pavements in high-UV-radiation regions.