Characteristics And Mechanism Of Styrene Butadiene Styrene Polymer Modified Asphalt

Base asphalt performance evaluation methods or their partially modified ones have been directly adopted by polymer modified asphalt. Whether it is suitable to SBS modified asphalt is one of the hot research points all over the world. This paper discussed the limitations of the present specification, focused the researches on the "process" evaluation criterion based on the existing tests and put forward the determination method of viscosity-temperature diagram and construction temperature.Three types of base asphalt and six SBS were used to produce SBS modified asphalt. The interaction of SBS modified asphalt was discussed in different states between the base asphalt and SBS based on their compositions. Through the traditional tests, such as penetration, soften point and ductility, and US SHRP tests, the results indicated that influences to affect the temperature susceptibility, high and low temperature performance, aging characteristics are base asphalt, SBS types and their dosages. The functions of penetration to viscosity and complex shear modulus G^* to complex dynamic shear viscosity η^* were set up, and then theviscosity-temperature susceptibility (VTS) of wide temperature span and the calculation method of low temperature viscosity were obtained. "Process" evaluation criterions, high grading critical temperature T_HS and low grading criticaltemperature T_LC , were suggested according to the high and low temperatureperformances of SBS modified asphalt. Using the experience of Repeated Creep and Recovery Test for Binders (RCRB), a new high-temperature evaluation index,modification rutting factor G^*(sinδ)^-9 was obtained. The results after RTFO and PAV aging indicated that traditional tests didn't differentiate base asphalt and SBS modified asphalt, but dynamic mechanics temperature spectrum and G*-5 black chart clearly reflected the influence of aging to the SBS modified asphalt. With the IR and GPC tests, the reason of aging to the SBS modified asphalt were due to asphalt phase oxygenated and SBS phase depredated. With the Superpave Gyratory Compactor (SGC) tests of SBS modified asphalt mixtures at different temperature and the relationship between viscosity and shear rate, a shear rate 60(1/s) was suggested, and the construction temperature was determined according to the viscosity ranges:...