Quantifying the blending efficiency of warm mix asphalt-synchronous rejuvenated SBS-modified asphalt through a dynamic shear rheometer (DSR) testing approach

The degree of blending (DOB), which is controlled by the diffusion between virgin and aged/rejuvenated asphalt binder, has a major impact on the performance of the asphalt mixture incorporated with reclaimed asphalt pavement (RAP). Despite numerous studies investigating the DOB through experimental methods, the blending efficiency of warm mix asphalt (WMA) and synchronous rejuvenated SBS-modified asphalt (SBSMA) is still unexplored. In this study, a dynamic shear rheometer (DSR) testing approach was developed to quantify the blending efficiency of WMA modified SBSMA and synchronous rejuvenated SBSMA. The novelty of this approach lies in the innovative use of a DSR asphalt double-layer structure to determine the DOB in combination with a developed theoretical calculation framework. The individual and synergistic effects of WMA additive and rejuvenator type on the DOB of WMA modified SBSMA-Synchronous rejuvenated SBSMA were investigated, while the influence of blending temperature, blending time, and dosage of aged/rejuvenated SBSMA on the blending efficiency were systemically evaluated. Results indicated that the SBS repairing agent in the synchronous rejuvenator can dramatically increase the DOB, while the presence of WMA additive can further increase the DOB by improving the fluidity of the virgin SBSMA. Furthermore, increasing the blending temperature/blending time and decreasing the dosage of aged/rejuvenated SBSMA were also conducive to enhancing the DOB. In addition, a blending chart of the WMA modified SBSMA-Synchronous rejuvenated SBSMA was developed to facilitate the accurate prediction of the DOB at any given blending temperature and blending time.