Modelling and optimization of viscoelastic flow behaviour of thermoplastic resin modified asphalt binder in dynamic shear domain

Abstract

In response to the increasing demand for high-temperature durability in asphalt pavements, the modification of asphalt binders using thermoplastic resin (TPR) additives has gained attention due to their aromatic structure, chemical compatibility, and ability to improve rutting resistance. This study investigates the viscoelastic flow behavior and performance optimization of TPR-modified asphalt (TPRMA) binders through a comprehensive experimental and numerical modeling framework. A petroleum-derived thermoplastic resin was incorporated into a 70/100 penetration grade asphalt binder at different ratios (1 %, 3 %, 5 %, 7 %). Rheological characterization was performed using Dynamic Shear Rheometer (DSR) tests under a wide range of temperatures and frequencies. Master curves of complex viscosity were constructed using time-temperature superposition and fitted with Cross and Carreau-Yasuda models. Both models showed excellent agreement with experimental data (R-2>0.99), with 5 % TPR yielding the highest zero-shear viscosity and lowest critical shear rate. In the second phase of the study, Response Surface Methodology (RSM) was employed to optimize the G*/sin delta parameter, a critical indicator of rutting resistance. RSM model was developed (R-2=0.9922; p < 0.0001), and numerical optimization identified 5.702 % TPR at 64 degrees C as the optimum formulation, producing a predicted G*/sin delta value of 5453.91 Pa. Post-analysis confirmed the statistical reliability of the prediction, with tight confidence and tolerance intervals enclosing the target response. Regression coefficient analysis further emphasized the dominant effects of temperature, TPR content, and their interactions. Overall, the findings highlight that moderate dosages of thermoplastic resin, particularly around 5 %, significantly enhance the high-temperature performance of asphalt binders.