Screw extrusion process used in the polymer modified asphalt field: A review

Polymer modified asphalt (PMA) has been widely used in asphalt pavement due to its excellent mechanical properties. However most polymer modifiers are not specifically designed for asphalt modification, leading to issues such as incompatibility when blended with asphalt. Meanwhile, the rapid expansion of highway network has led to a growing diversity of demands for polymer modified asphalt, but it is quite challenging to persuade the refineries to adjust their polymers specifically for asphalt modification. Therefore, suppliers are increasingly turning to tailor the polymer modifiers themselves using screw extrusion. Screw extrusion is a manufacturing process that involves using a rotating screw to push the material through an extrusion head to achieve functions like blending, shaping or certain chemical reaction. It is widely used in the polymer field due to its versatility, continuous production capabilities and relatively lower cost. This paper aims to provide an overview of the application of screw extrusion process in the asphalt material field. Based on ingredients and processing purposes, the examined papers are categorized into six applications: i) Plastic compound; ii) Crumb Rubber (CR) compound; iii) Rapid-melting pellet; iv) Nanomaterial compound; v) Grafting; vi) Devulcanization of CR. Furthermore, summary and discussion on the compound formulas and extrusion parameters are provided.