Study on combustion characteristics and thermodynamic model of SBS modified asphalt

To evaluate effects of Styrene-Butadiene-Styrene (SBS) on combustion characteristics of asphalt, kinetic models of asphalt combustion were developed. Firstly, thermogravimetric (TG) analysis was used to test combustion properties of SBS and asphalt. Then, combustion kinetics of asphalt was modeled based on thermodynamic theory. Finally, combustion characteristics of SBS modified asphalt (SBSMA) were evaluated by pyrolysis parameters and thermodynamic parameters. The results showed that both SBS and asphalt exhibited three stages of combustion, but stability of SBS was better than that of asphalt. SBS made pyrolysis temperature of asphalt increase significantly, while the pyrolysis rate of stage Ⅱ of SBSMA was reduced remarkably. The Coats-Redfern (CR) method was only suitable for kinetic model construction of base asphalt (BA), the Kissinger-Akahira-Sunose (KAS) method was better adapted to pyrolysis kinetic of both BA and SBSMA. The pyrolysis parameters and thermodynamic parameters showed that SBSMA was more difficult to be ignited and sustain combustion compared with BA. In this study, the kinetic models of SBS and asphalt were constructed to analyze the combustion characteristics and to establish a theoretical foundation for the subsequent research and development of asphalt safety and flame retardant for tunnels.