A Study On SBS Modified Asphalt

In this paper, SBS modified asphalt was studied through studying the structure and performance of asphalt. In the study of asphalt, a lot of different asphalt was separated into four fractions: asphaltenes, saturates, aromatics and resins. The surface structure and body structure of asphalt was distinguished by ATR (Attenuated Total Reflection). The thermal oxidation processes of four fractions of asphalt in different atmosphere were practiced by means of In-situ FTIR. The isothermal and non-isothermal processes were studied by TGA. The low-temperature and high-temperature performance of asphalt was respectively studied by means of DSC and DMTA. Each kind of asphalt with YH-791, YH-792, YH-801 and YH-802 was respectively blended. Penetration and softening point of each kind of asphalt and the SBS modified asphalt were determined. DSC and DMTA were also used to study the separation of SBS modified asphalt. The results are as follows:1. Asphalt, of which aromatics and resins has obvious difference in colors is liable to appear segregation after modifying with SBS. That is, SBS modified asphalt, of which saturates and aromatics has little difference in polarity has better high temperature storage stability.2. More saturates exist on surface of asphalt.3. Not mainly the ageing of resins and asphaltenes but that of saturates and aromatics cause the ageing of asphalt. Moreover, asphalt contains a large amount of saturates and aromatics and more saturates exist on the surface of asphalt, therefore, to solve the ageing of asphalt should firstly improve the oxidation resistance ability of saturates and aromatics. The study is totally different to the common idea about ageing of asphalt.4. The study shows that saturates and aromatics will loose a rather large amount of weight during storage at 160~180℃. Each kind of asphalt has different weight loss because the content and structure of each kind of asphalt are different. During long storage, it is necessary to add some amount of saturates and aromatics into different asphalt, which can avoid poor performance because of loss of some fractions.5. Asphalt has strong temperature sensitivity. The storage modulus decreases as temperature increases. During high temperature region, asphalt with high storage modulus has better resistance to distortion.6. As for the asphalt from the same place, it has lower Tg with higher content of saturates. Asphalt with lower Tg means better low-temperature performance.7. SBS modified asphalt appears segregation during high temperature storage. Samples in bottle of the tube get stiff. The elasticity get poor and the value of tan δ get higher. Samples in top of the tube get soft. The elasticity get better and the value of tan δ get lower.8. The change of heat absorption of DSC curves can be applied to judge high temperature storage of SBS modified asphalt.