Bitumen, a sticky black bonding agent derived from crude oil, plays a strong role in determining how long asphalt lasts. Bitumen itself is actually a combination of various components. In this case, a key issue is how good these components blend together. This depends on the polarities of the components.
The researchers were able to get certain components of the material to glow with the help of laser light, which in turn gave them insights into the composition of the material. However, the asphaltene (the largest bitumen components) did not glow but rather a layer made of aromatic compounds, which stretched around the asphalt inlays of only a few micrometers like a shell.
"This protective layer is ultimately responsible that bitumen and asphalt are tear-resistant, elastic but still relatively rigid“, explained Bernhard Hofko, a construction engineer at the Vienna University of Technology. However, if asphalt is left lying on the ground for a long time, it could damage the protective casing. The consequence is that the material loses its flexibility and becomes brittle and fragile. The researchers believe is now conceivable that a method can be developed to give back certain substances to the asphalt, and thus achieve a rejuvenation of the roads.
Service: The publication on the Internet (abstract): http://go.apa.at/Tg4lFaIW