The purpose of a soil classification system is to provide a concise and systematic method of identifying materials in order to characterize their probable engineering behavior. Soil classification permits comparisons between materials and provides a basis for accumulating experience gained with soils. This report is a state-of-the-art examination of existing soil classification systems with emphasis on classification of cohesionless soils. The purpose of the report is to note and suggest possible improvements to the Unified Soil Classification System currently used by the Corps of Engineers. Characteristics of soil types pertaining to roads and airfields and soil stabilization are also considered. Criteria for differentiating between coarse-grained soil groups which have diverse engineering properties, but which are not fully described in other classification systems, are also proposed. Boundaries between clean gravels or sands, gravels or sands with some fines, gravels or sands with fines, and fine-grained soils are suggested as 5, 20, and 50 percent fines, respectively. Coarse-grained soils are also classified with respect to their coefficient of uniformity and coefficient of curvature as well graded and poorly graded, with the poorly graded further separated into narrow (i.e. uniform) and gap gradations. Criteria to separate each group are presented. The Atterberg fraction (i.e., material passing No. 40 (425-mu n) U.S. standard series sieve) is separated into categories of low, intermediate, high, very high, and extremely high liquid limit. It is also proposed that the No. 10 (2.00-mm) sieve be used to separate gravel- from sand-size particles. /Author/

  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    3909 Halls Ferry Road
    Vicksburg, MS  United States  39180-6199
  • Authors:
    • Al-Hussaini, M M
  • Publication Date: 1977-11

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 61 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00172358
  • Record Type: Publication
  • Report/Paper Numbers: Misc Paper S-77-21 Final Rpt.
  • Files: TRIS, ATRI
  • Created Date: Apr 26 1978 12:00AM