ASTM D4221-99

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Designation:D4221–99
Standard Test Method for
Dispersive Characteristics of Clay Soil by Double
Hydrometer
This standard is issued under the fixed designation D 4221; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1193 Specification for Reagent Water
D 2216 TestMethodforLaboratoryDeterminationofWater
1.1 This test method, when used in conjunction with a test
(Moisture) Content of Soil and Rock
performed by Test Method D 422 on a duplicate soil sample,
D 3740 Practice for Minimum Requirements for Agencies
provides an indication of the natural dispersive characteristics
Engaged in the Testing and/or Inspection of Soil and Rock
of clay soils (1).
as Used in Engineering Design and Construction
1.2 This test method is applicable only to soils with a
D 4318 Test Method for Liquid Limit, Plastic Limit, and
plasticity index greater than 4 as determined in accordance
Plasticity Index of Soils
with Test Method D 4318 and more than 12 % of the soil
D 4647 Test Method for Identification and Classification of
fraction finer than 5-µm as determined in accordance with Test
Dispersive Clay Soils by the Pinhole Test
Method D 422 (2).
D 4753 Specification for Evaluating, Selecting, and Speci-
1.3 ThistestmethodissimilartoTestMethodD 422,except
fying Balances and Scales for Use in Testing Soil, Rock,
that this method covers the determination of percent of soil
and Related Construction Materials
particles smaller than 5-µm in diameter in a soil-water suspen-
E 1 Specification for ASTM Thermometers
sion without mechanical agitation and to which no dispersing
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
agent has been added.
poses
1.4 The amount of particles smaller than 5-µm determined
E 100 Specification for ASTM Hydrometers
by this method compared with the total amount of particles
E 145 Specification for Gravity-Convection and Forced-
smaller than 5-µm determined by Test Method D 422 is a
Ventilation Ovens
measure of the dispersive characteristics of the soil.
1.5 This test method may not identify all dispersive clay
3. Terminology
soils. Pinholes (Test Method D 4647 and crumb tests, or both,
3.1 Definitions:
(3-5)or the analysis of pore water extract (4-7) may be
3.1.1 dispersive clays—soils that disperse (deflocculate)
performed to help verify dispersion.
easily and rapidly without significant mechanical assistance in
1.6 This standard does not purport to address all of the
water of low-salt concentration.
safety concerns, if any, associated with its use. It is the
3.1.1.1 Such soils usually have a high proportion of their
responsibility of the user of this standard to establish appro-
adsorptive capacity saturated with sodium cation although
priate safety and health practices and determine the applica-
adsorbed lithium and magnesium may also play a role (6).
bility of regulatory limitations prior to use.
Such soils also generally have a high shrink-swell potential,
2. Referenced Documents havelowresistancetoerosion,andhavelowpermeabilityinan
intact state.
2.1 ASTM Standards:
3.2 For other definitions relating to this standard, refer to
D 422 Test Method for Particle-Size Analysis of Soils
Terminology D 653.
D 653 Terminology Relating to Soil, Rock, and Contained
Fluids
4. Summary of Test Method
4.1 The percent passing the 5-µm size is determined using
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
test procedures in Test Method D 422.
and Rock and is the direct responsibility of Subcommittee D18.06 on Physico-
Chemical Properties of Soils and Rocks.
Current edition approved June 10, 1999. Published September 1999. Originally
published as D 4421 – 83. Last previous edition D 4221 – 90. Annual Book of ASTM Standards, Vol 11.01.
The boldface numbers in parentheses refer to the list of references appended to Annual Book of ASTM Standards, Vol 14.03.
this standard. Annual Book of ASTM Standards, Vol 14.02.
3 7
Annual Book of ASTM Standards, Vol 04.08. Annual Book of ASTM Standards, Vol 14.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4221
4.2 The percent passing the 5-µm size is determined using 6.9 Timing Device—Awatch or clock capable of being read
the test procedures in this test method. This test method differs to the nearest second.
from Test Method D 422 primarily in that no mechanical 6.10 Distilled Water, with a pH 5.5–7.
agitation nor chemical dispersants are used.
NOTE 2—Trace minerals may be present in some Type IV water.
4.3 The percent dispersion is calculated by dividing the
However,sincethisisaqualitativetest,suchmineralsshouldnotaffectthe
percent passing the 5-µm size using this test method by the
test results.
percent passing the 5-µm size obtained using Test Method
6.11 Drying Oven,conformingtotherequirementsofSpeci-
D 422 and by multiplying the result by 100.
fication E 145.The oven should be thermostatically controlled,
preferably of the forced-draft type, and capable of maintaining
5. Significance and Use
a uniform temperature of 110 6 5°C throughout the drying
5.1 Dispersive clays are those which normally deflocculate
chamber. The temperature should be verified every four
when exposed to water of low-salt concentration, the opposite
months.
of aggregated clays that would remain flocculated in the same
7. Sample Preparation
soil-water system (3, 4, 7). Generally, dispersive clays are
highly erosive, possibly subject to high shrink-swell potential,
7.1 Sieve approximately 200 g of soil through a 2.00-mm
may have lower shear strength, and have lower permeability (No. 10) sieve. If materials are quite moist, this may require
rates than aggregated clays.
hand rubbing or use of a rubber-tipped pestle to force material
5.2 Available data (1) indicates that the test method has through the sieve. It is recommended that this test be per-
about 85 % reliance in predicting dispersive performance
formed at natural water content. When samples are very moist,
(85 % of dispersive clays show more than 35 % dispersion). they should be dried to about the plastic limit before proceed-
5.3 Since this test method may not identify all dispersive
ing with the test.
clays, design decisions based solely on this test method may 7.2 Collect a representative sample of about 100 g of
not be conservative. It is often run in conjunction with the
material passing the No. 10 sieve for water content determi-
crumbtest(4,7),thepinholetestgiveninTestMethodD 4647, nation and retain the remainder of the minus No. 10 material in
or the analysis of pore water extract (4, 7), or combination
an airtight container.
thereof, to identify possible dispersive clay behavior. 7.3 Determine the water content of the minus No. 10
material in accordance with Test Method D 2216.
NOTE 1—Notwithstanding the statement on precision and bias con-
tained in this test method; the precision of this test method is dependent
8. Procedure
on the competence of the personal performing it, and the suitability of the
8.1 Obtain 50 g of oven-dried soil in accordance with 7.3.
equipment and facilities used. Agencies that meet the criteria of Practice
D 3740 are generally considered capable of competent and objective Determine the percent passing 5 µm in accordance with Test
testing.
...