Pyrolysis properties of four SARA fractions in asphalt.

Pyrolysis property is an important safety issue for asphalt materials. It is important to study the asphalt pyrolysis properties for selecting flame-retarding technology to improve the fire safety of asphalt materials. Differential scanning calorimeter–thermogravimetry–Fourier-transform infrared spectroscopy was used to analyze the main pyrolysis temperature range, thermal effects, and emitted volatiles of saturates, aromatics, resins and asphaltenes (SARA) fractions. The microscopic morphology, the elemental compositions and their contents of each SARA fraction pyrolysis residues were tested by environmental scanning electron microscope–energy-dispersive spectrometer. The results indicate that main pyrolysis temperature range of SARA fractions is 250–550 °C, of which saturates have the lowest initial pyrolysis temperature, successively followed by aromatics, resins and asphaltenes. Also, SARA fraction pyrolysis processes are mainly endothermic reactions. The main volatiles in the pyrolysis of SARA fractions are alkanes and a small amount of CO, CO2 and SO2. Finally, the morphology and their elemental compositions of pyrolysis residues of SARA fractions are different. Among them, the proportion of O element is decreased from saturates to aromatics, resins and asphaltenes while the proportion of C is basically increased. [ABSTRACT FROM AUTHOR]