Study On Compatibility Of Waste Plastic-modified Asphalt

Production engineering and shear temperature, rotating speed of shearer, shear time, and so on, have important influence on the property of modified asphalt. Process parameters of direct shear method using high speed shearing machine and masterbatch method using double screw extruder was optimized, and property of PE-modified asphalt prepared under optimized process parameters was compared with that of PP-modified asphalt prepared under optimized process parameters. It is shown that, softening point of modified asphalt prepared by masterbatch method is higher than that of prepared by direct shear method. In the phase shift concentration, performance of PE modified asphalt prepared under optimized process parameters (by direct shear method and by masterbatch method) can meet the qualification of JTJF40-2004Ⅲ-C, performance of PP-modified asphalt prepared under optimized process parameters (by direct shear method and by masterbatch method) can meet the qualification of JTJF40-2004Ⅲ-D.High-temperature storage separation test of PE modified asphalt and PP modified asphalt prepared by direct shear method was made, and PE modified asphalt and PP modified asphalt were stirred at different temperature after modifier separated from asphalt. The experimental objective is to investigate dispersibility of PE modified asphalt and PP modified asphalt after modifier separated from asphalt. The result shows that PE modified asphalt and PP modified asphalt can return to the original property under certain stirring condition and temperature.PE-modified asphalt and PP-modified asphalt can not meet the specification by adding stabilizer into them. SBS (styrene- butadiene–styrene block copolymer) and SBR (styrene-butadiene rubber) containing active functional groups and prone to stability were melted with PE and PP to form PE-SBS, PP-SBS, PE-SBR and PP-SBR rubber-plastic complex substance to prepare rubber-plastic composite-modified asphalt. Storage stability of PE-SBS, PP-SBS, PE-SBR and PP-SBR modified asphalt were investigated by adding stabilizer. Fluorescence microphotograph and storage stability test show that PE-SBS, PP-SBS, PE-SBR and PP-SBR can form stable system with asphalt, SBS and SBR effectively stop congregation of PE and PP particles, and make modified asphalt system stable. The minimal proportion of rubber to plastics to prepare stable modified asphalt was investigated. The influence of proportion of rubber to plastics and modifer addition means on phase shift concentration of modified asphalt were investigated by changing proportion of rubber to plastics, adding modifier by different means. The influence of oil rich in aromatic and oil rich in saturates on softening points of modified asphalt prepared by different proportion of rubber to plastics and different addition means were investigated by adding oil rich in aromatic and oil rich in saturates to select the best compatilizer. The results show that proportion of rubber to plastics and modifer addition means can lead to variation of phase shift concentration, and the best compatilizer of modified asphalt prepared by different proportion of rubber to plastics and modifer addition means is different. Rubber-plastic modified asphalt prepared by different addition means can be stable by adding stabilizer and meet the qualification of specification of JTJF40-2004Ⅲ-C. Differential scaning calorimety (DSC) and infrared analysis show tha PE and PP have good compatibility with SBR and SBS. The combination of rubber with plastics is mainly physical, and reduce crystallinity degree of PE and PP in various degrees.High and low temperature performance of asphalt were evaluated with regular indices, the results show that the selected 17 typical modified asphalt samples (plastic modified asphalt, different proportion rubber-plastic modified asphalt and rubber modified asphalt) has higher softening point, lower penetration compared with base asphalt, namely, high temperature performance is improved. 5℃ductility of SBS modified asphalt, SBR modified asphalt, PE-SBR-4 (PE:SBR=1:1) modified asphalt, PP-SBR-3 (PP:SBR=2:1) modified asphalt and PP-SBR-4 (PP:SBR=1:1) modified asphalt are improved, namely, low temperature performance is improved and others are reduced. High and low temperature performance of asphalt were evaluated by PG (performance grade) method, the results show that high temperature performance of the selected 17 modified asphalt is improved compared with base asphalt, low temperature performance of other modified asphalt is reduced except SBS modified asphalt, SBR modified asphalt, PE-SBR-4 (PE:SBR=1:1) modified asphalt, PP-SBS-4 (PP:SBS=1:1) modified asphalt. The test of waste PE modified asphalt mixture, SBS modified asphalt mixture and base asphalt mixture was made, Marshall test shows that Marshall stability of waste PE modified asphalt (the larger Marshall stability is, the better high temperature performance asphalt has) > stability of SBS modified asphalt mixture > stability of base asphalt mixture. Bending beam rheometer (BBR) test results show that rupture strain of SBS modified asphalt mixture (the larger rupture strain is, the better low temperature performance asphalt has) > rupture strain of PE modified asphalt mixture > rupture strain of base asphalt mixture. The test results of Marshall stability and BBR rupture strain of PE modified asphalt mixture, SBS modified asphalt mixture and base asphalt mixture under the optimized proportion of asphalt to stone both meet the qualification of asphalt mixture specification.