Details:

Creators:
Sang Lee, Min ; Seok Choi, Yoon ; Prezzi, Monica
Sang Lee, Min ; Seok Choi, Yoon ; Prezzi, Monica Less -
Corporate Creators:
Joint Transportation Research Program (Ind.)
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Base Course (Pavements) Direct Shear Tests Geogrids Interfaces Moisture Content Quality Control Reinforcement (Engineering) Soft Soils Soil Stabilization Subgrade (Pavements) Tensile Strength
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.


Format:
PDF
Funding:
SPR-3225
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:2c04b361eecd1df560a4d6973fd9c0fe1cd320fb2f5968891a4fb24c609c8fc3
Download URL:
https://rosap.ntl.bts.gov/view/dot/26192/dot_26192_DS1.pdf
File Type:

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