http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
effects of asphalt fractional composition on properties
Chemical Engineering xviii, 256 leaves : illustrations ; 28 cm.
Oxidative aging is one of the major causes of asphalt pavement failure. To evaluate the age hardening resistance of asphalts, an aging model has been developed, which identifies the parameters representing performance-related aging properties. The model recognizes the fact that oxidative aging is the combined result of asphalt oxidation which results in carbonyl growth and the deterioration of physical properties caused by the chemical composition change. The kinetic parameters for carbonyl growth were found to be asphalt dependent. For the ten asphalts studied, the reaction activation energies range from 83 kJ/mol to 100 kJ/mol, while the pressure reaction orders range from 0.33 to 0.58. Two other important parameters are the initial jump and the hardening susceptibility. Both of these two parameters were found to be dependent on aging pressure, with the sensitivities being highly asphalt dependent. However, these two parameters are independent of aging temperature. The aging characteristics of Corbett fractions and supercritical fractions were investigated to study the effects of fractional composition on the aging properties of whole asphalts. The kinetic characteristics of an asphalt are determined by the kinetic characteristics of its fractions as well as the interaction between the fractions. The polar aromatics fractions oxidize much more rapidly than the naphthene aromatics fractions. They also have higher hardening susceptibilities and viscosity temperature susceptibilities. The data collected in this study suggest that it may be possible to produce an asphalt binder with superior performance-related properties via supercritical ftactionation. In particular, when one of the light supercritical fractions is aged to a viscosity level of an AC-20 asphalt, the material has a much lower HS value and reactivity than the parent asphalt. Its viscosity temperature susceptibility is a bit smaller than the whole asphalt, and increases less for the same amount of carbonyl growth. Saturates only have a dilution effect on the oxidation rate of asphalts, while asphaltene addition increases asphalt oxidation. Data explicitly show that naphthene aromatics convert to polar aromatics, and subsequently to asphaltenes. The asphaltenes and polar aromatics produced by aging naphthene aromatics are smaller in molecular size than those present in the original asphalt.
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Includes bibliographical references: pages 180-185.