Micro-heterogeneous modification of an asphalt binder using a dimethylphenol and high-impact polystyrene solution

This study proposes a modified asphalt binder using a solution of high-impact polystyrene (HIPS) and 2,6-dimethylphenol (DMP). The oxidative polymerization of 2,6-dimethylphenol synthesizes a thermoplastic polymer (polyphenylene oxide, PPO) in the presence of copper, amines, and vanadium in the asphalt binder. The polymerization and existence of PPO were verified using X-ray diffraction and Fourier transform infrared (FTIR) spectroscopic analyses. The maximum crystallinity of the solution occurred after a mixing time of 2 h with a homogenizer mixing energy of 3000 rpm. The rheological properties of the DMP- and HIPS-modified binder are also investigated using a dynamic shear rheometer (DSR) and a bending beam rheometer (BBR). The modified asphalt binder exhibits an increase in |G*|/sin(δ) of 2.14 kPa at 82 °C without aging, which improves in the high-temperature rut resistance of the modified binder. The modification does not significantly affect the low-temperature crack resistance of the binder, considering that the m-value and stiffness at −12 °C are 0.31 and 237 MPa.