00450694

Component

http://onlinepubs.trb.org...s/trr/1984/999/999-006.pdf

https://scholar.google.co...hler&publication_year=1984

Because a widely accepted laboratory durability test for asphalt does not exist, many agencies including the Pennsylvania Department of Transportation (DOT) have resorted to controlled field experiments to evaluate and characterize those physical properties of the asphalt binder that are associated with aging and their relationship to pavement performance. Three asphalt durability projects undertaken by the Pennsylvania DOT are summarized in this paper: 1961-1962 test pavements, 1964 test pavements, and 1976 test pavements. The study was limited to the evaluation of dense-graded asphaltic concrete wearing courses in which a different asphalt source or type was used. Except for the 1961-1962 test pavements, the only significant variable was the asphalt type. Mix composition and construction techniques were held reasonably constant. After construction, periodical core samples were obtained from these pavements to determine the percentage of air voids and the rheological properties of the aged asphalts. It has been observed that aging of the pavements results in progressively lower penetration and higher viscosity, which exhibit a hyperbolic function with time. However, the accompanying decrease in low-temperature ductility after the penetration falls below 30, and the rate of gain in shear susceptibility relative to increase in viscosity at 77ousF, have been found to be important factors that affect the pavement performance. Lower ductility values were associated with a higher incidence of load-associated longitudinal cracking. High stiffness modulus of the asphalt cement at low temperatures and a 20,000-sec loading time contributed to nonload-associated transverse cracking. In the discussion, Davis notes that his own experience supports the authors contentions and he proposes that the ductility test could serve as a viscometer if stress levels were recorded.

Publication of this paper sponsored by Committee on Characteristics of Bituminous 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

01419880

Davis, Richard L

pp 41-50

1984

Transportation Research Record

0309038081

Print

Figures (8) ; References (11) ; Tables (11)

Age; Air voids; Asphalt; Bituminous binders; Ductility; Durability; Field tests; Low temperature; Night; Rheology; Shear strength; Viscosity

Pennsylvania

Pennsylvania

Highways; Materials; I31: Bituminous Binders and Materials

TRIS, TRB

Feb 28 1986 12:00AM

• CHANGES IN ASPHALTS
• CHEMICAL COMPOSITION OF ASPHALT AS RELATED TO ASPHALT DURABILITY: STATE OF THE ART
• Physical Properties as Related to Asphalt Durability: State of the Art
• REFINERY ECONOMICS
• Refinery Processing of Asphalt Cement (with discussion and closure)
• Significant Studies on Asphalt Durability: California Experience