Investigation of road bitumen ageing by Fourier transform IR spectroscopy

Thermo-oxidative ageing of qualified and unqualified blow road bitumen and their feed (sludge) were investigated in this work. Thermo-oxidative ageing was carried out by developed ageing procedure at 163 degrees C, 180 degrees C, 200 degrees C and 220 degrees C. Oxidation rate was monitored by Fourier-transform infrared spectroscopy in terms of intensity of the absorbance by carbonyl functional groups which has maximum in 1700 cm(-1). According to the results oxidation rate of unqualified bitumen is higher over the entire temperature range. Induction period was observed in experiments at 163 degrees C only. For qualified bitumen induction period is thrice as much than for unqualified. Sludge samples for qualified and unqualified bitumen production demonstrated the same tendency. Thus, differences in rate and depth of thermo-oxidative ageing are associated with the content of feed. Inorganic impurities can strongly influences the ageing tendency. It was shown that FTIR can be used for the rapid evaluation of the tendency to oxidative ageing.