Lab Services: Soil testing
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Test Method Title
Standard Method of Test for Unconfined Compression Strength of Cohesive Soil
AASHTO T 208
Strength, stress-strain relationship
Description of Test
This method covers the determination of the unconfined compressive strength of cohesive soil in the undisturbed, remolded, or compacted condition, using strain-controlled application of the axial load. This test method is applicable only to cohesive materials which will not expel bleed water during the loading portion of the test and which will retain intrinsic strength after removal of confining pressures, such as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands cannot be tested with this method to obtain valid unconfined compressive strength values.
Preferred Test Sample Size
2.87 diameter x 3 ft Shelby tube
Number of Test Specimens
Test Specimen Size
Minimum of 1.3 in diameter, with a height-to-average diameter of 2-2.5, with minimum particle size 1/10 the diameter.
Cohesive soil, sensitivity, strain-controlled loading, strength, stress-strain relationships, unconfined compression