AASHTO T 216-07 (2020) PDF Download

The AASHTO T 216-07 (2020) standard provides procedures for determining the consolidation properties of soils in one-dimensional conditions. The test involves applying controlled-stress loading to the soil while it is restrained laterally and drained axially.

Two alternative procedures, Test Method A and Test Method B, are described in the standard. Test Method A requires time-deformation readings on a minimum of two load increments, with a constant load increment duration of 24 hours or multiples thereof. Test Method B requires time-deformation readings on all load increments, with successive load increments applied after 100 percent primary consolidation or at constant time increments.

The standard notes that this test method is commonly performed on undisturbed samples of fine-grained soils naturally sedimented in water. However, it can also be applied to compacted soils and undisturbed samples of soils formed by weathering or chemical alteration. Special evaluation techniques may be necessary for soils other than those naturally sedimented in water.

It is the responsibility of the agency requesting the test to specify the magnitude and sequence of each load increment, including the location of a rebound cycle if necessary. For Test Method A, the agency must also specify the load increments for which time-deformation readings are desired. Alternatively, Test Method B can be used where time-deformation readings are taken on all load increments.