Author(s):
R.N. Traxler
Publication Date
December 1962
Abstract
Objectives: Investigate paving asphalts used by THD to determine how they can be evaluated for qualities and their durabilities improved.|Experimental: A number of representative paving asphalts were analyzed by (1) a modified Traxler and Schweyer Component Analysis procedure using pentane, butanol and acetone, (2) a modified Pitchford and Axe method using pentane, isopropanol and acetone, and (3) the Rostler analytical procedure using pentane, 85%, 98%, and fuming sulfuric acid. The data obtained were correlated with oxidation of 15-micron films of each asphalt for 2 hours in a dark oven at 225°F, and in some cases with photo oxidation of 15-micron films under radiation from a 175 Watt Mazda Sunlamp for 2 hours at 190°F. Changes in composition caused by oxidation were determined. A correlation was established between Saturates content by the Traxler and Schweyer method and viscosity of the asphalt at 275°F.|CONCLUSIONS: 1. Dispersion Coefficients calculated from a modified Traxler and Schweyer Component Analyses correlate well with susceptibilities to oxidation as measured by Relative Viscosities. Asphalt No. 8 is the one exception among the asphalts investigated.|2. Dispersion Coefficients do not correlate very well with susceptibilities of the asphalts to photo oxidation.|3. Data obtained by a modified Pitchford and Axe procedure correlate well with susceptibilities to oxidation.|4. The coefficient established by Rostler does not correlate well with durability as measured by the Relative Viscosities of oxidized films. A modified Rostler coefficient gave an improved correlation but was not equal to that calculated from a modified Traxler and Schweyer Component Analysis.|5. Oxidation of 1/8 inch films for 15 hours at 325°F results in a definite increase in Asphaltene content and a marked decrease in percent Resins. There is a tendency for Cyclics (unsaturated or aromatic oils) to increase during oxidation, Saturates (paraffinic oils) may increase or decrease depending on the source of the asphalt.|6. Percent Saturates correlate fairly well with the high temperature viscosities of the asphalts.
Report Number:
9-5
Link(s):
Document/Product
http://tti.tamu.edu/documents/9-5.pdf
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