Modeling and optimization of rheological properties and aging resistance of asphalt binder incorporating palm oil mill waste using response surface methodology

This study assessed the rheological performance of asphalt binder modified with palm oil clinker fine (POCF) and its influence on the asphalt binder's short-term aging properties. The conventional properties of unaged and short-term aged asphalt binders modified with 0%, 2%, 4%, 6%, and 8% POCF content by binder weight were evaluated. The modified binders were then tested using a dynamic shear rheometer (DSR) in a temperature sweep test at temperatures ranging from 25 ​°C to 55 ​°C. To examine the effect of various POCF contents and temperature ranges on the rheological behavior of asphalt binders, the Central Composite Design (CCD) Response Surface Methodology (RSM) design was used with two input response variables, POCF content and temperature, and two rheological parameters as responses, complex modulus, and phase angle. When compared to the virgin binder, POCF-modified binders had higher complex modulus and lower phase angle values at all temperatures. Furthermore, the stiffness of the aged-modified binder was lower at all temperatures than that of the virgin binder. The analysis shows that complex modulus and phase angle have high correlation coefficients (R²) of <0.98, indicating that the model values are strongly correlated with the experimenttal values. The model also demonstrates that temperature has more influence on the rheological performance of the modified binder. Using the generated quadratic model and numerical optimization, optimal values for POCF and temperature were found to be 5.57% and 41.9 ​°C, respectively. The validation test results show that all responses have a percentage error of <5%, indicating good agreement and the model's effectiveness.