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Title: RELATIONSHIPS BETWEEN MOLECULAR WEIGHTS AND RHEOLOGICAL PROPERTIES OF ASPHALTS
Accession Number: 00730227
Record Type: Component
Record URL: Availability: Find a library where document is available Abstract: It is known that the rheological properties of mixtures of organic compounds are functions of molecular weight distributions. However, with respect to asphalts, which are composed of many different compounds and compound types, molecular weights are difficult to measure. This difficulty occurs because the molecular associations that form are held together by forces of varying strengths and are partly broken up by heat and solvents. In theory, the strongest molecular associations in asphalts should have the greatest influence on the rheological properties of asphalts. These associations would be expected to be the major contributors to the asphalt's behaving as if it were a relatively high molecular weight material. Asphalt molecular associations should be isolatable by means of size exclusion chromatography. Several fractions of varying molecular weights (measured by membrane osmometry and vapor phase osmometry) were isolated from Strategic Highway Research Program (SHRP) asphalt AAD-1 by preparative size exclusion chromatography. Molecular weights of these fractions ranged from approximately 2,000 daltons to over 40,000 daltons. When these fractions were independently mixed with asphalt AAD-1 solvent moiety, mixtures were obtained whose rheological properties were a function of the molecular weights and concentrations of the associated materials. These results support the microstructural model of asphalt proposed during SHRP. The results also suggest that the unusual rheological properties of some asphalts may be explained by measuring molecular weight distributions. This type of information may be useful for modification of asphalts to achieve desirable rheological properties.
Supplemental Notes: This paper appears in Transportation Research Record No. 1535, Characteristics of Asphalt Binders.
Language: English
Corporate Authors: Transportation Research Board 500 Fifth Street, NW Authors: Branthaver, J FRobertson, R EDuvall, J JPagination: p. 10-14
Publication Date: 1996
Serial: ISBN: 0309059100
Features: References
(15)
; Tables
(7)
TRT Terms: Identifier Terms: Uncontrolled Terms: Old TRIS Terms: Subject Areas: Freight Transportation; Highways; Materials; I31: Bituminous Binders and Materials
Files: TRIS, TRB
Created Date: Dec 12 1997 12:00AM
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