Research Information System
Arabian Journal for Science and Engineering, 2025 (SCI-Expanded)
The pavement industry promotes sustainable practices by integrating waste materials into asphalt production. Among these, crumb rubber (CR) has long been successfully used, though there is still no consensus and standardization on its production process. Therefore, this study systematically investigates the asphalt–rubber interaction mechanisms considering the mixing rate and duration on physical and rheological properties of wet process CR-modified asphalt (CRMA) binders. Based on the literature and practice, 12 CRMA binders are produced using conventional and high shear mixing (1000 and 5800 rpm), across six durations (30, 60, 90, 120, 150, or 180 min). The effects of these variables on physical and rheological properties were studied experimentally and statistically. Moreover, the CR-binder interaction mechanism is analyzed by fluorescence microscopy imaging in different aging phases. It is observed that the mixing method significantly influences the consistency, temperature susceptibility, and aging resistance of CRMA binders due to the rate of degradation of CR particles. Results reveal that CRMA binders prepared with high shear mixing enhance aging resistance, and the binders with conventional mixing yield lower temperature susceptibility and improved rutting resistance. Moreover, the noteworthy effect of mixing duration is only observed in consistency and long-term aging resistance, though a 90-to-120-min mixing duration is identified as an optimal range for a stable performance. Eventually, high shear mixing may be suggested for colder regions, where a softer binder is needed for easy handling and good performance, while conventional mixing is favorable for warmer areas. Ultimately, the mixing method considerably influences the overall performance.