AASHTO T 208-15 (2019) PDF Download

The AASHTO T 208-15 (2019) standard is a method for testing the unconfined compressive strength of cohesive soil. The test involves applying axial load to the soil in its undisturbed, remolded, or compacted state using strain-controlled loading. The purpose of this test is to provide an estimate of the strength of cohesive soils under total stress conditions.

It is important to note that this test method is only applicable to cohesive materials that do not expel bleed water during the loading phase and retain their intrinsic strength after removal of confining pressures. Examples of suitable materials for this test include clays and cemented soils. On the other hand, materials such as dry and crumbly soils, fissured or varved materials, silts, peats, and sands are not suitable for this method as they would not yield valid unconfined compressive strength values.

It is worth mentioning that this test method is not a substitute for determining the unconsolidated, undrained strength of cohesive soils with lateral confinement, which is covered by a different AASHTO standard - T 296.