While atomic force microscopy and scanning electron microscopy have provided information on the morphology of bitumen surfaces in the past, it was not known whether surface and chemical composition correlate with each other. However, the chemical composition of the surface is of particular interest because oxidation processes take place there, triggered by oxygen-containing molecules in the air such as ozone, nitrogen oxides or hydroxyl radicals. The oxidation process accelerates the aging of the material—the bitumen becomes porous and damage develops.
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Source: Phys.org