Quality assessment of geogrids used for subgrade treatment.

Details

• Creators:
  Sang Lee, Min ; Seok Choi, Yoon ; Prezzi, Monica
• Corporate Creators:
  Joint Transportation Research Program (Ind.)
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Subgrade (Pavements)
  • Geogrids
  • Soft soils
  • Direct shear tests
  • Soil stabilization
  • Base course (Pavements)
  • Tensile strength
  • Moisture content
  • Quality control
  • Interfaces
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• Publication/ Report Number:
  FHWA/IN/JTRP-2012/27
• Resource Type:
  Tech Report
• Geographical Coverage:
  Indiana
• Corporate Publisher:
  Indiana. Dept. of Transportation
• NTL Classification:
  NTL-HIGHWAY/ROAD TRANSPORTATION-HIGHWAY/ROAD TRANSPORTATION ; NTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and Performance
• Abstract:
  Geogrid reinforcements have been used by the Indiana Department of Transportation (INDOT) to construct stable subgrade foundations ; and to provide a working platform for construction over weak and soft soils. Use of geogrid reinforcement in a pavement system ; ensures a long‐lasting pavement structure by reducing excessive deformation and cracking. The main objectives of this research were to ; evaluate the mechanical interaction between a subgrade soil and an aggregate base layer with and without a geogrid in place at the ; interface. A series of large‐scale direct shear tests were performed to investigate the effects of geogrid properties, such as geogrid ; aperture area, junction strength, and tensile strength, on the interface shear strength of soil‐geogrid‐aggregate systems. The test results ; showed that the aperture size and junction strength of the geogrids were relatively important factors affecting the overall interface ; shear strength the most. The average values for the peak interface shear strength coefficient for the three normal stresses (50 kPa, 100 ; kPa and 200 kPa) considered in this study ranged from 0.96 to 1.48. In addition, the test results showed that the average peak interface ; shear strength coefficient increases with increases in the junction strength of the geogrid. The optimum aperture area of the geogrid ; was found to be equal to 825 mm2 (1.4 in2) for the subgrade soil and aggregate considered in this study. There was no significant ; correlation between the geogrid tensile strength at 2% strain and the average peak interface shear strength coefficient. The effect of the ; moisture content of the subgrade soil on the peak interface shear strength coefficient was also investigated. The peak interface shear ; strength coefficient for the subgrade soil sample prepared at the optimum moisture content and compacted to relative compaction ; values of 94–96% (Rsoil = 95–96% and Raggregate = 94–95%) and tested under a normal stress of 100 kPa was 20% less than that for the ; subgrade soil sample prepared at a moisture content 4% above the optimum moisture content. Based on the results of the tests ; performed in this study, an aperture area requirement of 825 mm2 (1.4 in2) and a junction strength requirement of 11.5 kN/m (788 lb/ft) ; were suggested as preliminary guidelines for subgrade reinforcement systems. These requirements are only limited to the use of Type IV ; geogrid (INDOT specification 207.04) for subgrade reinforcement with aggregate No. 53.
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• Format:
  PDF
• Funding:
  SPR-3225
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26192/dot_26192_DS1.pdf
• File Type:
  [PDF - 7.02 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:d20a35d12cfa4556cb6d670e23580d50e1f49c271f7fc56cf11892ab938d086d2e4e10cb6f919e18b3bad908a927bf5f16de53be723b617aa067ac4ef9e82ba6