PERFORMANCE OF GEOTEXTILE SEPARATORS IN WESTERN WASHINGTON. FINAL TECHNICAL REPORT

Fourteen geotextile separators, with different in-service ages, were exhumed in western Washington and their short (survivability) and long-term (filtration/drainage) performances were evaluated. The geotextile samples, which included six woven slit-films, six needle-punched nonwovens, and two heat-bonded nonwovens, were taken back to the laboratory in order to evaluate their overall condition and to perform permittivity and strength tests on specimens of each fabric. Samples of the subgrade and base materials were also evaluated in the laboratory. The results indicated that all of the geotextile separators adequately performed their intended separation function, although they experienced very different levels of damage during construction. There was evidence of in-service mechanical damage at one of the sites. The damage to the geotextiles was influenced more by the base aggregate type, rather than the initial lift thickness, although both must be considered in design. All of the recovered geotextiles which were installed under an angular base aggregate sustained damage to some degree. Even two heavier weight fabrics, a 231 g/sq m woven slit-film and a 204 g/sq m needle-punched nonwoven, sustained damage under angular base material. All of the fabrics which were installed under subrounded to rounded base aggregate experienced minor to no damage. The woven slit-films and the needle-punched nonwovens experienced similar reductions in strength and both survived the installation conditions reasonably well (except for one lightweight needle-punched nonwoven fabric which was overstressed during installation and also may have been installed under too thin of a pavement section). The heat-bonded nonwovens were heavily damaged during installation; however, they were installed under some of the higher site survivability conditions. The results of the permittivity tests indicated that the woven slit-films and the needled-punched nonwovens both had similar percent increases after being washed. The heat-bonded nonwovens had the highest percent increases in permittivity after being washed, which suggests that they clog more than the other fabrics. There is evidence that the woven slit-films experienced much more blinding than the other fabrics, and that iron staining and caking could also have a detrimental effect on their drainage performance. In all but one case, the woven slit-film fabrics did not meet the Task Force 25 (1989) and Christopher and Holtz (1989) filtration requirements needed for the subgrade soils with which they were in contact. The unwashed (i.e., "undisturbed") permittivity results also indicate that most of the permeabilities of the woven slit-film fabrics fell well below WSDOT's required value. The presence of caked fines on the upper surface of three woven slit-films could have indicated that their pore openings were too large for the intended filtration function and they might be subject to fines migration, although this was inconclusive. There was no evidence of fines migration at any of the sites. All of the pavements were in good condition.

• Record URL:
  • http://www.wsdot.wa.gov/research/reports/fullreports/321.1.pdf
• 
• Corporate Authors:

  Washington State Transportation Center

  University of Washington, Seattle
  Seattle, WA  United States  98195

  Washington State Department of Transportation

  Transportation Building, 310 Maple Park Avenue SE, P.O. Box 47300
  Olympia, WA  United States  98504-7300

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Metcalfe, R C
  • Holtz, R D
• Publication Date: 1994-5

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 277 p.

Subject/Index Terms

• TRT Terms: Aggregates; Aggregates by shape and surface texture; Base course (Pavements); Evaluation; Geotextiles; Loss and damage; Nonwoven materials; Pavements; Performance evaluations; Permeability; Time duration; Woven fabrics
• Uncontrolled Terms: Aggregate shape; Damages; Long term; Pavement conditions; Short term
• Old TRIS Terms: Permittivity tests
• Subject Areas: Geotechnology; Highways; Materials; Pavements; I33: Other Materials used in Pavement Layers;

Filing Info

• Accession Number: 00664319
• Record Type: Publication
• Report/Paper Numbers: WA-RD 321.1
• Contract Numbers: Agreement T9233, Task 13
• Files: TRIS, USDOT, STATEDOT
• Created Date: Aug 15 1994 12:00AM