The effect of air blowing on the properties and constitution of a natural bitumen

Air blowing of a natural and vacuum-reduced bitumen causes marked changes in the properties and constitution of the material. The products are harder and have higher softening points than the original material and the changes in physical properties appear to be related to the asphaltene content which increases with the temperature and duration of the blowing process. Analytical data indicate that conversion of the original resins to asphaltenes and the formation of new resins from the oils occur simultaneously; the data also provide feasible representations of the pathways of bitumen maturation and asphalt deterioration.