Deformation Mechanism and Bearing Strength of Bituminous Pavements

The mechanical behavior of bituminous pavements and their substructures is of importance in relation to the stresses acting on them. This paper deals with the deformation mechanism of such structures and the measurement of the bearing strength, defined as the maximum load per unit area which a bituminous pavement can carry without causing initial failure. The deformation of bituminous pavements consists of an instantaneous and retarded elastic deformation followed by a plastic deformation. The mechanical behavior is primarily determined by the plastic deformation which is accompanied by hardening. As a result of the hardening process, the coefficient of plastic traction, which is stress over strain rate and is related to the viscosity, increases with increasing compressive stress and time to a maximum within a certain region of stress. At this point the shearing stress and shear are zero, and the maximum coefficient of plastic traction is an isotropic or volume viscosity, i.e., the material behaves like a solid. The principal stress corresponding to this maximum coefficient is the bearing strength. At greater stresses the coefficient of plastic traction decreases rapidly and the material is in the region of failure. A bituminous pavement at rest is conceived as containing simultaneously particles in the disordered state and in the ordered state. The latter state refers to positions of minimum potential energy. Under stress the particles in the ordered state rarely escape their positions, while the remaining particles move from positions of disorder to those of order. At the maximum value of the coefficient of plastic traction the number of particles in the disordered state approaches zero. The change in free energy of activation in going from a disordered to an ordered state and the mass of a particle are also maximums at this point. The process of hardening is comparable to a fusion of the disordered particles into a particle of larger mass. The theory of the mechanical behavior of bituminous pavements applies also to the base course and subsoil, as shown by data from bearing-plate measurements.

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/33/33-012.pdf
• Supplemental Notes:
  • 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.
• Authors:
  • Mack, Charles
• Publication Date: 1954

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; Tables;
• Pagination: pp 138-166
• Monograph Title: Proceedings of the Thirty-Third Annual Meeting of the Highway Research Board, Washington, D.C., January 12-15, 1954
• Serial:
  • Highway Research Board Proceedings
  • Volume: 33
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Bearing tests; Bituminous pavements; Deformation; Deformation curve; Loads
• Subject Areas: Highways; Pavements; I22: Design of Pavements, Railways and Guideways;

Filing Info

• Accession Number: 01492890
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Sep 16 2013 7:57AM