PHOTOOXIDATION OF CORBETT FRACTIONS OF ASPHALT

Oxidation of asphalt causes the degradation and failure of asphalt pav ement. Due to the molecular complexity and relatively high molecular w eight of asphalt, the oxidation mechanism is complicated by the intera ctions among the molecules of different types. To minimize the interac tions, the asphalt sample was chromatographically separated into satur ates, naphthalene aromatics, polar aromatics, and asphaltenes. These C orbett fractions were then oxidized under ultraviolet irradiation. Fou rier-transform infrared spectroscopy was used to analyze the structura l changes of the Corbett fractions during photooxidation. All Corbett fractions have shown sign:ificant spectral changes in the region of 35 00 - 3100 cm(-1) characterized the stretching vibrations of hydroxyl o r nitrogen-hydrogen groups, the peak around 1700 cm(-1) featured carbo nyl groups, and in the region of 1320 - 1000 cm(-1) characterized the formation of sulfur-containing functional groups. Strong evidence has shown that sulfates are produced in the oxidation of asphalt. The form ation of sulfates provides an essential explanation for the deteriorat ion of asphalt pavement.