Preparation and Performance of SBR/SiO ₂ ‐Modified Emulsified Asphalt Mixtures Incorporating Recycled Aggregates

To address the technical bottlenecks associated with the poor overall performance of emulsified asphalt mixtures incorporating high‐proportion (84 wt%) recycled asphalt pavement (RAP) aggregates, this study proposes a synergistic modification strategy using styrene‐butadiene rubber (SBR) and nano‐silica (SiO 2 ), coupled with the regulation of cement and polyester fiber contents. Through systematic rheological characterization and performance testing, the results demonstrate that SBR/SiO 2 modification is able to enhance the high‐temperature properties of the emulsified asphalt binder, as evidenced by a reduced penetration, a lower phase angle, and an increased complex modulus. Meanwhile, this modification also slightly affects the low‐temperature performance of the asphalt binder by boosting its ductility and reducing its creep stiffness (S); however, the m ‐value was decreased. Fourier transform infrared spectroscopy (FTIR) results demonstrate that the synergistic effect between SBR and SiO 2 is physical in nature. The optimal formulation for the asphalt mixtures was ultimately determined as follows: 3.9% binder modified by 3.5 wt% SBR and 3 wt% nano‐SiO 2 , 1.5 wt% cement, and 0.3 wt% polyester fiber, achieving a splitting strength of 0.82 MPa, a dynamic stability of 4683 times/mm, a flexural strain of 2526 με, and a freeze–thaw splitting ratio of 83.3%. This research establishes a basis for the high‐value utilization of RAP aggregates in emulsified asphalt mixtures and contributes to the advancement of low‐carbon, sustainable pavement materials.