IMPORTANT PROPERTIES OF BASE AND SUBGRADE MATERIALS

Various transfer functions relating flexible pavement structural responses (stresses, strains, displacements) and pavement performance have been proposed for use in mechanistic flexible pavement design procedures. Appropriate material and soil inputs are essential for good flexible pavement analysis and design. The major recent emphasis in granular material and subgrade soil characterization/evaluation has been on repeated load testing. Resilient moduli and permanent deformation behavior of granular materials and subgrade soils can be quantified based on appropriate repeated load testing data. In a well designed high-type flexible pavement system the permanent strain accumulated per load cycle is very small compared to the resilient strain. Base course granular material quality is controlled by specification requirements. Typical material specifications consider L.A. Abrasion, soundness, degree of crushing (relates to the geometric properties of shape, angularity, and surface texture), gradation, liquid limit and PI (or sand equivalent), and some measure of strength (CBR is frequently used). The specifying agency can thus control granular base quality and characteristics within narrow limits. In sharp contrast to "well controlled" granular materials, the subgrade is an in-situ material. Adequate subgrade characterization requires consideration of the fluctuations of subgrade soil properties as a function of space (various depths in a subgrade and transverse and longitudinal location along the project) and time (seasons of the year and year-year climatic variation).

• Supplemental Notes:
  • Proceedings of the Conference on Crushed Stone for Road and Street Construction and Reconstruction, held June 14, 15, 1984, Arlington, Virginia.
• Corporate Authors:

  National Crushed Stone Association

  1415 Elliot Place, NW
  Washington, DC  United States  20007
• Authors:
  • Thompson, M R
• Publication Date: 0

Media Info

• Features: Figures; References; Tables;
• Pagination: 41 p.

Subject/Index Terms

• TRT Terms: Accelerated tests; Base course (Pavements); Dislocation (Geology); Flexible pavements; Granular materials; Pavement design; Pavement performance; Properties of materials; Repeated loads; Resilience (Materials); Soils; Specifications; Strain (Mechanics); Stresses; Subgrade (Pavements)
• Uncontrolled Terms: Soil properties
• Old TRIS Terms: Strains
• Subject Areas: Design; Geotechnology; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I36: Aggregates;

Filing Info

• Accession Number: 00455591
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 31 1986 12:00AM