A few years back we worked on a retaining wall project near the Boise River where the contractor had ordered a geogrid based purely on tensile strength ratings from the catalog. The soil there is silty sand with some cobble layers, and the wall faced differential settlement within two winters. That experience taught us that geogrid specification in Boise Idaho has to account for the local alluvial deposits and the freeze-thaw cycle that hits the Treasure Valley hard. We now run site-specific pullout tests and verify that the grid's aperture size matches the aggregate gradation on site. Before finalizing any design, our team cross-checks the reinforcement layout with a subgrade CBR evaluation to confirm that the base layer can support the required loads without excessive deformation.
A geogrid specification that ignores local alluvial soil behavior and freeze-thaw cycles is a liability waiting to settle.
Method and coverage
Regional considerations
What we see most often in Boise Idaho is that geogrids get specified from a generic table without checking the site's groundwater depth or the plasticity of the subgrade. When the water table rises in spring, fine particles can migrate through an oversized aperture and reduce the interface friction. Another common problem is using a uniaxial grid where a biaxial one would provide better confinement for the granular base. We also find that contractors sometimes omit the required overlap at the roll ends, which creates weak seams. To avoid these issues, we recommend running a direct shear test on the soil-geogrid interface with the actual fill material — that gives you real interaction coefficients instead of assuming values from a brochure.
Standards that apply
ASTM D6637-18 – Tensile properties of geogrids, AASHTO M288-21 – Geosynthetic reinforcement of aggregate base, GRI-GG2 – Standard test method for junction strength, IBC 2021 Section 1807 – Soil reinforcement and retaining structures
Related services
Pullout and interface testing (ASTM D6706)
We perform in-situ pullout tests to measure the actual bond resistance between the geogrid and the site-specific backfill. This data eliminates the guesswork from design assumptions and helps you optimize the embedment length.
Wide-width tensile testing (ASTM D6637)
Our lab verifies the manufacturer's claimed tensile strength, creep behavior, and junction efficiency. We issue a certified report that can be submitted alongside the geogrid submittal for plan approval.
Typical parameters
Top questions
What is the difference between a uniaxial and a biaxial geogrid for Boise Idaho projects?
A uniaxial geogrid has most of its tensile strength in one direction and is used for retaining walls and steep slopes where the main load is horizontal. A biaxial geogrid distributes strength in both directions and works better for base reinforcement under roads and parking lots, especially on the silty subgrades common in the Treasure Valley.
How much does a geogrid specification service cost in Boise Idaho?
The typical range for a complete geogrid specification package — including pullout testing, tensile verification, and a written report — falls between US$360 and US$1.270. The final cost depends on the number of grid types tested and the complexity of the fill material.
Which ASTM standards are most relevant for geogrid specification in Idaho?
The three key standards are ASTM D6637 for wide-width tensile testing, ASTM D6706 for pullout resistance, and ASTM D5321 for direct shear of the soil-geogrid interface. The Idaho Division of Highways also references AASHTO M288 for aggregate base reinforcement.