Determination of chemical and physical properties of two asphalts of different origin
Date
2008
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Abstract
It is shown in this thesis that there is a definite relationship between the chemical and physical properties of asphalts; however, it is very complex due to the concurrent actions of various material properties. The chemical properties of the compounds present in the asphalts, such as their chemical structure, polarity, molecular weight, their mutual interaction and probably many others, are more important for asphalt's overall behaviour than just the amount of the compounds themselves. The chemical properties of the two asphalts of different origins showed that the asphalt, with a lower content of asphaltenes, was actually more stiff and brittle at low and mid temperatures than the asphalt with higher asphaltene content. On the other hand, asphalt with higher asphaltene content revealed higher viscosity at high temperatures. This fact clearly shows that the asphaltene content itself cannot be used as a general indicator of asphalt's viscosity when comparing two different asphalts, especially at low temperatures. It seems that the content and chemical character of the low-polar asphalt fractions (saturates, naphthene aromatics, waxes) plays very important role in both, lowtemperature and high temperature properties of tested asphalts as these fractions tend to become hard at low temperatures but easily soften at high temperatures. On the other hand, the content and chemical character of the highly polar fractions (polar aromatics, asphaltenes) in asphalt is more important for its "good" behaviour at higher temperatures. The results show that especially the molecular weight, its distribution, and polarity of present chemical compounds appear to play one of the most important roles in the asphalt's overall physical behaviour. Low content of easily oxidizable "benzylic" carbons and aliphatic sulphur atoms reveals to be important for good long term performance of asphalt binder and its low temperature susceptibility. Overall increase in viscosities of tested asphalts reveals to be a result of increased molecular weight and polarity of present chemical compounds because of oxidative aging.
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Bibliography: p. 208-225
Some pages are in colour.
Some pages are in colour.
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Citation
Michalica, P. (2008). Determination of chemical and physical properties of two asphalts of different origin (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/2019