Experimental Observations of Mixing in an Aggregate and Fine Grained Soil System Subjected to Cyclic Loading with and Without Geotextile Separator

Geotextiles have been employed as separators between base and subgrade layers in pavements, but the presence of such a layer has effects on the mechanics and hydraulics of the system that are not well understood. Consequently, it is of interest to understand subgrade and loading conditions that lead to mixing. We thus conducted a repeated load triaxial testing program to examine mixing of coarse aggregate placed over a layer of silt. The dry density of silt, that was saturated prior to loading, was varied and the layered specimens were cyclically loaded over a range in deviatoric stresses without a geotextile. For silt compacted near maximum standard density, unsaturated specimens with and without a geotextile separator were tested as was a specimen with a separator in which the silt was saturated. On-specimen deformation gauges provided information on strains within each layer and across the interface between them. Mixing occurred in layered aggregate/silt specimens due either to downward movement of the aggregate or a combination of downward movement of the aggregate and upward movement of fines. Geotextile separators prevented mixing of the two materials in two medium-density silt specimens. When the silt was not saturated prior to testing, the geotextile separator improved system deformation. When the silt was saturated, the separator led to greater deformation possibly due in part to consolidation of the silt. Due to differences between experimental and field conditions, the geotextile performance should not be extrapolated to the field.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; Photos; References;
  • Pagination: 23p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01044057
  • Record Type: Publication
  • Report/Paper Numbers: 07-2881
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 7:35PM