1.1This test method presents a direct, measurement of the dispersibility and consequent colloidal erodibility of clay soils by causing water to flow through a small hole punched in a specimen. The results of the tests are qualitative and provide general guidance regarding dispersibility and erodibility. This test method is complemented by Test Method D4221.
1.2This test method and the criteria for evaluating test data are based upon results of several hundred tests on samples collected from embankments, channels, and other areas where clay soils have eroded or resisted erosion in nature (1).
1.3Three alternative procedures for classifying the dispersibility of clay soils are provided as follows:
1.3.1Method A and Method C, adapted from Ref (1), classify soils into six categories of dispersiveness as: dispersibility (D1, D2), slight to moderately dispersive (ND4, ND3), and nondispersive (ND2, ND1).
1.3.2Method B classifies soils into three categories of dispersiveness as: dispersibility (D), slightly dispersive (SD), and nondispersive (ND).
1.4All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.5Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.6This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.