Abstract: Most of the pyrolysis and combustion of asphalt is under the oxygen-poor environment during tunnel fire. In order to study the effects of ambient oxygen concentration on asphalt under real fire, the pyrolysis kinetic characteristics of 10# asphalt under different oxygen volume concentrations (0, 7% , 15% ,21% ) were investigated by thermogravimetric (TG) analysis.The pyrolysis process of asphalt under different oxygen concentration was studied, and the kinetic analysis was performed. Results showed that there is only one main weight-loss stage in the pyrolysis process of asphalt in the atmosphere of 0% (N2) oxygen concentration, and the ratio of residual mass is the highest.Presence of oxygen in the atmosphere change the weight- loss stagefrom one to three, and the ratio of residual mass is less than 10%. With the increase of oxygen concentration, the initial decomposition temperature of asphalt and the pyrolysis speed increases, the weight- loss rate in the high- temperature section accelerates, while the activation energy in the low- temperature section decreases. The reaction process basically consistent with the diffusion model. The activation energy in high-temperature section is the highest at 21% oxygen concentration, and the reaction model changes from the diffusion model when the oxygen is poor to the three-stage simple model.

Key words: asphalt, oxygen concentration, pyrolysis, kinetics