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Proper use of rejuvenators can improve the properties and performance of aged asphalt mixtures; however, there is currently a lack of understanding on how rejuvenator treatment details, such as type-dosage of rejuvenators and blending-curing of rejuvenation, affect properties and performance characteristics. This study aims to investigate the effects of type, dosage, and treatment methods of rejuvenators when added into aged bituminous materials. To meet the goal, three rejuvenators, categorized by their production technology, were selected to improve a high-recycled asphalt pavement mixture by conducting various binder-level and mixture-level tests. For the binder-level testing, the performance grading (PG) method was used to primarily determine proper dosages targeting desired binder grades, and two chemical tests (Fourier-transform infrared spectroscopy and Saturate, Aromatic, Resin and Asphaltene) were conducted to examine chemical characteristics altered by rejuvenation and the further aging process. The selected dosage levels from the binder testing were then applied to mixture-level performance evaluation by conducting two tests: flow number for rutting and semicircular bending fracture for cracking. Test-analysis results indicated that although it can successfully determine the proper dosage range of rejuvenators, PG binder testing is limited to only assessing the effects of rejuvenators on mechanical properties; this can be better aided by integrating chemical characterization that provides a more in-depth material-specific rejuvenation process. Moreover, it appears that rejuvenation methods can alter the performance of aged mixtures. Therefore, the selection of rejuvenators and their implementation into practice should be carried out considering multiple aspects, not only its PG recovery.

Cracking of bituminous materials is one of the main distresses that results in roadway failure. As bituminous media are highly rate‐dependent at intermediate temperatures due to the viscoelastic nature of the binding materials, cracking is also highly rate‐dependent viscoelastic. This presents a clear need to address the phenomenon in the modeling‐analysis process for a more accurate design of mixtures and pavements. This study proposes an advanced computational modeling method to predict complex rate‐dependent cracking in bituminous materials and pavements. In particular, we explored an extrinsic nonlinear viscoelastic cohesive zone (NVCZ) integrated with Gaussian damage evolution. To examine the modeling method and its validity, two modeling efforts in multiple length scales were made: mm‐scale material‐level modeling and cm‐m scale hierarchical modeling that linked the mixture with pavement structure. The NVCZ modeling with Gaussian damage evolution successfully predicted material cracking and damage at different loading rates by using a single set of fracture parameters. This implies that the complex cracking behavior of bituminous materials can be characterized by material‐specific fracture parameters that can be identified by a simple fracture test. The pavement modeling through a parametric analysis demonstrated the sensitivity and capability of the modeling to effectively capture the interrelated influence of several core design variables, such as traffic, material properties, and layer configurations, all of which affect pavement responses and damage evolution. The computational modeling presented in this study has the scientific rigor to predict nonlinear rate‐dependent viscoelastic fracture of bituminous materials and pavements with a good modeling efficiency by significantly reducing laboratory tests.