ASTM D 4221 - 99 (Reapproved 2005) Standard Test Method for Dispersive Characteristics of Clay Soil by Double Hydrometer

American Society for Testing and Materials (ASTM). Current edition approved June 1, 2005. Published December 2005. 3 p. This test method, when used in conjunction with a test performed by Test Method D422 on a duplicate soil sample, provides an indication of the natural dispersive characteristics of clay soils.
This test method is applicable only to soils with a plasticity index greater than 4 as determined in accordance with Test Method D4318 and more than 12 % of the soil fraction finer than 5-μm as determined in accordance with Test Method D422.