This paper which describes the design of bases and subbases for flexible pavements, briefly reviews the intended functions of bases and subbases and discusses in detail the basic pavement behavior and methods of measuring stability. The difficulty involved in attempting to isolate the effect of multiple variables is pointed out, and simplified treatment is presented of the complex problem of defining the functions of the various pavement layers in providing protection against cracking, rutting and shear deformation without relying too heavily on slab action, which may be "initially approached" by stiffer bases. The concept of thickness equivalency based on fixed, empirically derived strength coefficient for broad classes of materials is cited as fallacions. Capacity of flexible pavements is brought about by the load-distributing characteristics of the layered system. The behavior of such pavements under load is extremely complex. The stresses in the pavement can induce consolidation, shear failures, rutting, fatigue and other distress manifestations. Many methods are available for measuring various strength properties of base materials. These include the CBR test, Hveem Stabilometer Test, Plate Bearing Test, the Standard Triaxial Test, the Resilient Modulus Test (detailed) and others. Equivalency factors are discussed and it is pointed out that the use of such factors without considering the true characteristics of the material, climate and other factors can be dangerous. The designer must account for drainage, frost action, fatigue and many properties that are difficult to evaluate.

  • Supplemental Notes:
    • Proceedings from a conference on Utilization of Graded Aggregate Base Materials in Flexible Pavements, March 25-26, 1974, Oak Brook Hyatt House, Oak Brook, Illinois.
  • Corporate Authors:

    National Crushed Stone Association

    1415 Elliot Place, NW
    Washington, DC  United States  20007

    National Sand and Gravel Association

    900 Spring Street
    Silver Spring, MD  United States  20910

    National Slag Association

    300 South Washington Street
    Alexandria, VA  United States  22314
  • Authors:
    • Yoder, E J
  • Publication Date: 1974

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Filing Info

  • Accession Number: 00127528
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 7 1976 12:00AM