A LABORATORY STUDY OF FACTORS THAT INFLUENCE THE INSERVICE PERFORMANCE OF COMPACTED SUBGRADES

The objective of this research was to develop laboratory procedures for predicting the in-service performance of compacted subgrades. The study focused on the use of the gyratory testing machine as a laboratory device for evaluating the influence of traffic loads and environmental factors on subgrade behavior. In Part I, the responses of laboratory-compacted samples to gyratory testing are compared with the results of consolidation and CBR-like penetration tests. It is shown that the effects of initial moisture-density conditions, moisture changes and freeze-thaw cycles on the stiffness and compressibility of compacted soils may be evaluated by gyratory tests. In Part II, the responses of field- compacted samples are compared with the responses of laboratory-compacted samples prepared by impact, kneading and gyratory compaction methods. For limited moisture-density conditions studied, the behavior of the field- compacted samples was simulated equally well by all three laboratory compaction methods. This result is attributed in part to the fact that all moisture conditions considered were wet of optimum. Finally, recommendations and guidelines are presented for implementing gyratory procedures for (a) establishing compaction requirements, (b) evaluating soil support values for pavement design and (c) estimating the effects of increasing maximum allowable wheel loads on existing pavements. /FHWA/

• Supplemental Notes:
  • Sponsored by North Carolina Department of Transportation and Highway Safety in cooperation with DOT and FHWA.
• Corporate Authors:

  North Carolina State University, Raleigh

  Highway Research Program, P.O. Box 5993
  Raleigh, NC  United States  27607
• Authors:
  • Wahls, H
• Publication Date: 1975-4

Media Info

• Pagination: 141 p.

Subject/Index Terms

• TRT Terms: Bearing capacity; Compaction; Environmental impacts; Forecasting; Freezing; Gyratory testing machines; Laboratory studies; Performance; Subgrade (Pavements); Swelling index; Thaw; Traffic loads
• Uncontrolled Terms: Freeze thaw cycles
• Old TRIS Terms: Gyratory tests; Soil support value
• Subject Areas: Environment; Freight Transportation; Geotechnology; Highways;

Filing Info

• Accession Number: 00144121
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: FHWA-RD-76-S0554 Final Rpt., FCP 45C2201
• Contract Numbers: HP&R 68-1
• Files: TRIS, USDOT
• Created Date: Dec 15 1976 12:00AM