ASTM D425-88(1994)
(Test Method)Standard Test Method for Centrifuge Moisture Equivalent of Soils
Standard Test Method for Centrifuge Moisture Equivalent of Soils
SCOPE
1.1 This test method covers the determination of the moisture equivalent of soil in the laboratory by means of a centrifuge technique.
1.2 This test method is limited to disturbed specimens of coarse-grained soils having fines of low plasticity such as SP, SW, SC-SM, or SM soils. The test is limited to soils passing the 2.00-mm sieve or that fraction of a soil passing a 2.00-mm sieve.
Note 1—Test Method D 3152 or Test Method D 2325 should be used to evaluate the capillary-moisture relations of fine-grained soils and coarse-grained soils having fines of medium to high plasticity, undisturbed soils, and soils at specific desired units weights.
1.3 The test method is temperature-dependent, and consistent comparable results can be obtained only if the tests are performed under a constant-temperature condition.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 This 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 425 – 88 (Reapproved 1994)
Standard Test Method for
Centrifuge Moisture Equivalent of Soils
This standard is issued under the fixed designation D 425; 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.
e NOTE—Paragraph 6.1 was changed editorially in September 1988.
1. Scope fying Balances and Scales for Use in Soil and Rock
Testing
1.1 This test method covers the determination of the mois-
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
ture equivalent of soil in the laboratory by means of a
poses
centrifuge technique.
1.2 This test method is limited to disturbed specimens of
3. Terminology
coarse-grained soils having fines of low plasticity such as SP,
3.1 All definitions are in accordance with Terminology
SW, SC-SM, or SM soils. The test is limited to soils passing the
D 653. Terms of particular significance are as follows:
2.00-mm sieve or that fraction of a soil passing a 2.00-mm
3.2 capillary fringe zone—the zone above the free water
sieve.
elevation in which water is held by capillary action.
NOTE 1—Test Method D 3152 or Test Method D 2325 should be used
3.3 centrifuge moisture equivalent—the water content of a
to evaluate the capillary-moisture relations of fine-grained soils and
soil after it has been saturated with water and then subjected for
coarse-grained soils having fines of medium to high plasticity, undisturbed
one hour to a centrifugal force equal to 1000 times that of
soils, and soils at specific desired units weights.
gravity.
1.3 The test method is temperature-dependent, and consis-
3.4 specific retention—the ratio of the volume of water that
tent comparable results can be obtained only if the tests are
cannot be drained from a saturated soil under the action of
performed under a constant-temperature condition.
force of gravity to the total volume of voids.
1.4 The values stated in SI units are to be regarded as the
3.5 water-holding capacity—the smallest value to which the
standard.
water content of soil or rock can be reduced by gravity
1.5 This standard does not purport to address all of the
drainage.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 The centrifuge moisture equivalent of soils is deter-
bility of regulatory limitations prior to use.
mined by initially air-drying the soil, selecting two 5-g test
specimens, thoroughly soaking each test specimen, and then
2. Referenced Documents
determining the water content of each specimen after it has
2.1 ASTM Standards:
been centrifuged for1hata force equal to 1000 times that of
D 653 Terminology Relating to Soil, Rock, and Contained
gravity at a controlled temperature of 20 6 1°C.
Fluids
D 2216 Test Method for Laboratory Determination of Water 5. Significance and Use
(Moisture) Content of Soil, Rock, and Soil-Aggregate
5.1 Not all water contained in a saturated soil can be
Mixtures
removed by gravity drainage. The amount of water retained
D 2325 Test Method for Capillary-Moisture Relationships
after gravity drainage is usually expressed as water holding
for Coarse- and Medium-Textured Soils by Porous-Plate
capacity or specific retention. It varies with time, and with the
Apparatus
particle-size distribution and plasticity of the soil (in general,
D 3152 Test Method for Capillary-Moisture Relationships
increasing in value with increasing plasticity index).
for Fine-Textured Soils by Pressure-Membrane Apparatus
5.2 In general, the centrifuge moisture equivalent is based
D 4753 Specification for Evaluating, Selecting, and Speci-
on the theory of applying a centrifugal force great enough to
reduce the capillary fringe zone enough that it can be ignored
without introducing much error, even in small specimens, and
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
and Rock and is the direct responsibility of Subcommittee D18.03 on Texture, yet not so great as to withdraw a large proportion of the water
Plasticity, and Density Characteristics of Soils.
Current edition approved May 27, 1988. Published July 1988. Originally
e1
published as D 425 – 35 T. Last previous edition D 425 – 79 .
2 3
Annual Book of ASTM Standards, Vol 04.08. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 425
that is held securely above the capillary fringe. For example, if
where:
a soil will hold water 100 mm by capillarity acting against
N = revolutions per minute,
gravity, the soil will theoretically be able to hold the water only
RCF = relative centrifugal force (1000),
0.1 mm against a centrifugal force that is 1000 times greater r = radius of rotation to center of gravity of the test
than the force of gravity. It has been determined that for at least specimen, cm, and
m = mass of the body, taken as unity.
medium-textured soils (sandy to silty particle-size distribution)
the centrifuge moisture equivalent approximates the water
For normal equipment installation, N will equal approxi-
holding capacity and when combined with the bulk density can
mately 2300 rpm.
be used to calculate an approximate specific retention and
6.2 Gooch Crucible—A procelain Gooch crucible having a
specific yield. These properties when combined with porosity
perforated bottom, a capacity of approximately 25 mL, and a
can be used to estimate aquifer storage coefficient.
diameter at bottom of about 20 mm (Fig. 1). Crucibles should
be numbered and paired in such a way that their masses meet
6. Apparatus
the requirements of the manufacturer of the centrifuge.
6.3 Babcock Trunnion Cups—At least one pair of centrifuge
6.1 Centrifuge—A centrifuge of such a size and so driven
cups with caps and with a crucible holder for supporting the
that a force equal to 1000 times the force of gravity may be
Gooch crucible above the bottom of the cup (Fig. 1). The
exerted on the center of gravity of the soil specimen for 1 h.
holder shall have sufficient clearance to fit fully within the cup
The centrifuge chamber shall be capable of maintaining a
and short support the cup in such a manner that the water
controlled temperature of 20 6 1°C. The revolutions per
ejected during the centrifuging operation does not come in
minute, N, required to provide a centrifugal force of 1000 times
contact with the crucible and soil. Cups and crucible holders
gravity is determined from the equation:
should be balanced in pairs opposite each other in the centri-
RCF
fuge and should be numbered in pairs (for example, 1, 1A, 2,
N 5
˛
0.0000111 rm
2A, etc.).
(1)
6.4
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.