Preparation of direct injection waste PE/rubber powder composite modified granules and performance for recycling asphalt

PE/rubber powder composite modified granules were successfully prepared by twin-screw extruder using LDPE recycled material and waste rubber powder as the main raw materials. The preparation technology of rubber-plastic composite modified particles was studied. By controlling the index of melting rate, the composite modified particles suitable for direct injection method are produced. Then the optimal melting state and dis-persibility of the composite modified particles in the mixture were studied. The composite modified granules were mixed by the direct injection method and the performance of the extracted and recovered asphalt was tested to determine the optimal mixing process. The experimental results are as follows: according to melt flow rate index, the optimal preparation process of rubber-plastic composite modified particles is determined. The reaction temperature of zones 1-6 of the twin-screw extruder was determined to be 160 degrees C/180 degrees C/340 degrees C/ 340 degrees C/200 degrees C/180 degrees C. The screw speed of the main engine is determined to be 15r/min. The mesh number of waste rubber powder is determined to be 120 meshes; When the modified particles are added, with the increase of mixing time and other factors, the softening point and ductility of asphalt can be improved, and the pene-tration can be reduced. At the same time, the phase angle can be reduced in DSR, and the complex shear modulus can be increased; Based on the molten state grade index and asphalt performance index, the optimal mixing process of the modified asphalt mixture was determined. The mixing time is 60 s, the mixing temperature is 180 degrees C, and the mixing amount is 3 %. Under these conditions, the rubber-plastic composite modified asphalt has excellent performance.