This paper examines existing data on base course material behaviour, particularly permanent strain behaviour, in an attempt to define the variables that affect the recorded material response. Models for permanent strain are then examined in the light of these variables. The recent emphasis on permanent strain prediction has arisen through a need to design a pavement for more than elastic or rebound deflection. However, very little is known about the permanent strain behaviour of unbound base course materials under actual traffic conditions. Attempts have been made to isolate several variables which affect base course material behaviour - moisture content, grading, density, aggregate type, plasticity, stress level and load repetitions. However, several other important variables seen to have been ignored. The models that have been put forward to characterize permanent strain behaviour are often based on a reduced number of measured variables and the discrepancy between model and actual behaviour is large. The emphasis on characterization through statis tests often ignores the different structural changes that occur under trafficking as well as stress history, reorientation of load axes and compound loading conditions. Some reinterpretation of static tests may help link static and dynamic tests, but such proposals should be based on the actual fabric changes that occur under the statis test/dynamic test and field conditions. It is concluded that no model has been put forward which would adequately characterize base course material behaviour under realistic field conditions. /Author/

  • Corporate Authors:

    Commonwealth Scientific & Industrial Research Org

    314 Albert Street
    East Melbourne, Victoria,   Australia 
  • Authors:
    • Barrett, J R
  • Publication Date: 1976

Media Info

  • Features: Figures; References;
  • Pagination: 13 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00144430
  • Record Type: Publication
  • Source Agency: ARRB
  • Report/Paper Numbers: Tech Paper No. 26
  • Files: ITRD, TRIS
  • Created Date: Mar 30 1977 12:00AM