Phase behavior and hot storage characteristics of asphalt modified with various polyethylene: Experimental and numerical characterizations

Abstract

Abstract Phase behavior is crucial to multi-phase materials, which intensively affects macro-performance of materials. Polymer modified asphalt is a typical multi-phase material and widely applied in paving industry. This paper presents the fundamental understanding of phase behavior and hot storage characteristics of polyethylene (PE) modified asphalts. The influence of polymer structure on phase behavior was studied by experimental and numerical approaches. Experimentally, four typical PE modified asphalts were selected to prepare thin film slides of asphalt, which were subjected to isothermal annealing and observed under fluorescence microscopy (FM). The morphology evolutions were evaluated by statistical size distribution. Storage stability was further evaluated by tube test. Numerically, microstructure evolutions and storage stability were described by phase field method. The results showed that the scope of PE phase size distribution becomes wider during annealing. Linear low-density PE shows a relative slow separation. Phase-field model perfectly describes the experimental microstructure evolution. Polyethylene structural parameters significantly affect the phase behavior. Lower crystalline, higher melt flow index (MFI) as well as more branched molecule promotes the swelling of PE particle and the interaction of constituents. Moreover, differences in density and viscosity between PE and asphalt greatly accelerate the separation in the vertical direction.