This study investigates the usage of spent tire rubber-derived activated carbon (STRDAC) to improve the rheological properties and aging performance of bitumen blends. Design expert software was employed for the statistical modeling and optimization of two separate rheological parameters complex modulus and phase angle for both unaged and short-term aged samples. The rolling thin film oven test was employed to replicate short-term bitumen aging. We examined two important independent parameters in our experimental design: the STRDAC content, which varied from 0% to 12%, and the test temperature, which varied from 40°C to 70°C, whereas the responses were rheological and aging performance. The incorporation of STRDAC increased bitumen viscosity, changed flow behavior to thixotropic, enhanced resistance and stiffness, with higher complex modulus at elevated temperatures, and lower phase angle at intermediate temperatures, and improved aging resistance when compared to the pristine bitumen sample. This is attributed to the high presence and properties of the carbon black in STRDAC. Furthermore, the statistical response optimization developed model shows that the predicted values in the examined range agreed well with the actual outcome. The optimization outcome indicated that the optimal STRDAC content for improved performance was 6.49%, at a test temperature of 46.46°C. Furthermore, the statistical response optimization value was validated and the findings show a low error margin, indicating strong agreement between the model and actual values and demonstrating the model's efficiency. The outcome of the study shows a statistical response optimization is an effective tool for modeling and optimization of the bitumen rheological and aging resistance of STRDAC-modified bitumen.
Key words: Bitumen; Rheological properties; Spent tire rubber; Activated carbon; statistical response optimization; Modeling
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