Quality Assessment of Geogrids Used for Subgrade treatment

Construction of soil-geogrid-aggregate systems
Geogrid placement in the direct sear box
In December 2012, Monica Prezzi, Min Sang Lee, and Yoon Seok Choi completed "SPR-3225 Quality Assessment of Geogrids used for Subgrade Treatment." The project objective was 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.

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. The use of geogrid extends pavement life expectancy by reducing deformation and cracking and is a faster and more effective solution than chemical treatment. In addition, geogrids provide reinforcement by laterally restraining the subbase, thereby improving the bearing capacity of the pavement system and decreasing the shear stresses on the subgrade soil.

As a result of the project, INDOT has implemented new specifications of appropriate aperture area and junction strength requirements for supgrade soil-geogrid-aggregate systems based on the recommendations provided in the final report.

Lee, M., Choi, Y. and Prezzi, M. (2012). "Quality Assessment of Geogrids Used for Subgrade Treatment-Phase II." Publication FHWA/IN/JTRP-2012/27. Joint Transportation Research Program, Indiana Department of Transportation and Purdue University, West Lafayette, Indiana, 2012.  DOI: 10.5703/1288284315034.