|
|
|
Title: SOFTENING OF ASPHALTS IN DILUTE SOLUTIONS AT PRIMARY DISTILLATION CONDITIONS
Accession Number: 00669038
Record Type: Component
Availability: Find a library where document is available Abstract: Softening of asphalts in dilute solutions, often by as much as 50%, occurred in several instances during experiments using a modified Roto-vap recovery technique. The softening is caused by a mechanism that is characterized by Fourier transform infrared spectroscopy spectral growth near the traditional carbonyl region associated with oxidative hardening, as well as other minor changes. Gel permeation chromatograms of solvent-softened asphalts show formation of one and sometimes two new narrow peaks, suggesting that the reactions produce a very narrow range of products. Reaction rates vary considerably with asphalt source, solvent, and solution conditions. The rates also increase considerably with Roto-vap oil bath temperature from 102 deg C to 149 deg C. Reaction rates decrease with concentration, being almost nonexistent at 0.12 g/mL but generally significant at 0.06 g/mL. Reactions proceed faster in more polar extraction solvents, such as trichloroethylene with 15% ethanol (TCE/EtOH), than in toluene with 15% ethanol. Inhibitors such as butylated hydroxy toluene slow the reactions but do not appear to affect the extent of reaction. Compatible asphalts (such as SHRP AAG-1) react fastest at lower temperatures, whereas incompatible but reactive asphalts (SHRP AAK-1) react fastest at higher temperations. The reactions appear to be dependent on the solvent's ability to dissolve associated species. However, the reactions have also been detected in dissolved dilute solutions (below 0.15 g/mL) to temperatures above 93 deg C, especially in polar solvents such a TCE/EtOH, for extended periods of time.
Supplemental Notes: This paper appears in Transportation Research Record No. 1436, Asphalt Concrete Mix Materials. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
Monograph Title: Monograph Accession #: 01401249
Language: English
Authors: Burr, B LDavison, R RGlover, C JBullin, J APagination: p. 47-53
Publication Date: 1994-10
Serial: ISBN: 030905513X
Features: Figures
(13)
; References
(7)
; Tables
(1)
TRT Terms: Old TRIS Terms: Subject Areas: Highways; Materials; I31: Bituminous Binders and Materials
Files: TRIS, TRB
Created Date: Nov 23 1994 12:00AM
More Articles from this Serial Issue:
|
