The use of high-pressure-gel permeation chromatography to evaluate asphalt cements subjected to various mix production parameters
Abstract
The widespread adoption of the drum mix asphalt plant and the operating parameters associated with this plant has resulted in increased speculation as to the characteristics of the asphaltic concrete mix produced when compared with batch plant mixes. The use of lower grade burner fuels in both plants to dry the aggregate has furthered this concern. These concerns have recently reached a peak with reports of premature pavement failures due to these or other causes. In evaluating these problems, one technique to study asphalts that has been advanced by researchers is the use of high pressure-gel permeation chromatography (HPGPC). The major purpose of this study was to use this technique to evaluate the changes in asphalt subjected to different mix production parameters, including plant type, level of aging and fuel used in the burner of the drier. Additional objectives were to establish correlations between physical parameters of asphalts and their chromatographic parameters, and to determine whether the HPGPC technique could be used to detect burner fuel contamination in the mix produced by asphalt plants. Samples of asphalt cement, asphaltic concrete mix produced with these samples, and the burner fuels used to produce them were collected during the 1985 paving season. These samples, along with pavement cores taken after five years of service life were analyzed by physical and chromatographic techniques. Additionally, samples were artificially contaminated with burner fuels and evaluated. This study determined that the HPGPC technique is an excellent comparative analysis tool, capable of detecting changes in the aging of asphalt, but not repeatably capable of establishing direct relationships between chromatograms and physical parameters. Results of the study also show that no significant differences could be found by HPGPC between mixes produced by drum plants and batch plants, or by plants using different burner fuels. HPGPC can also detect fuel contamination at the 1% contamination level, not detectable by physical measures. Finally, results of this study show that the 5 hour thin film oven test does not simulate aging produced by asphalt plants, and should be reevaluated.
Degree
Ph.D.
Advisors
Wood, Purdue University.
Subject Area
Civil engineering
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.