ASTM D6572-21
(Test Method)Standard Test Methods for Determining Dispersive Characteristics of Clayey Soils by the Crumb Test
Standard Test Methods for Determining Dispersive Characteristics of Clayey Soils by the Crumb Test
SIGNIFICANCE AND USE
5.1 The crumb test provides a simple, quick method for field or laboratory identification of a dispersive clayey soil. The internal erosion failures of a number of homogeneous earth dams, erosion along channel or canal banks, and rainfall erosion of earthen structures have been attributed to colloidal erosion along cracks or other flow channels formed in masses of dispersive clay (5).
5.2 The crumb test, as originally developed by Emerson (6), was called the aggregate coherence test and had seven different categories of soil-water reactions. Sherard (5) later simplified the test by combining some soil-water reactions so that only four categories, or grades, of soil dispersion are observed during the test. The crumb test is a relatively accurate positive indicator of the presence of dispersive properties in a soil. The crumb test, however, is not a completely reliable negative indicator that soils are not dispersive. The crumb test can seldom be relied upon as a sole test method for determining the presence of dispersive clays. The double-hydrometer test (Test Method D4221) and pinhole test (Test Method D4647/D4647M) are test methods that provide valuable additional insight into the probable dispersive behavior of clay soils.
Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depends on several factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 Two test methods are provided to give a qualitative indication of the natural dispersive characteristics of clayey soils: Method A and Method B.
1.1.1 Method A—Procedure for Natural Soil Crumbs described in 10.1.
1.1.2 Method B—Procedure for Remolded Soil Crumbs described in 10.2.
1.2 The crumb test, while a good, quick indication of dispersive soil, should usually be run in conjunction with a pinhole test and a double hydrometer test, Test Methods D4647/D4647M and D4221, respectively. Since this test method may not identify all dispersive clay soils, other tests such as, pinhole dispersion (Test Methods D4647/D4647M), double hydrometer (Test Method D4221) and the analysis of pore water extraction (Test Methods D4542) may be performed individually or used together to help verify dispersion.
1.3 The crumb test has some limitations in its usefulness as an indicator of dispersive soil. A dispersive soil may sometimes give a non-dispersive reaction in the crumb test. Soils containing kaolinite with known field dispersion problems, have shown non-dispersive reactions in the crumb test (1).2 However, if the crumb test indicates dispersion, the soil is probably dispersive.
1.4 These test methods are applicable only to soils where the position of the plasticity index versus liquid limit plots (Test Methods D4318) falls on or above the “A” line (Practice D2487) and more than 12 % of the soil fraction is finer than 2-μm as determined in accordance with Test Method D7928.
1.5 Oven-dried soil should not be used to prepare crumb test specimens, as irreversible changes could occur to the soil pore-water physicochemical properties responsible for dispersion (2).
Note 1: In some cases, the results of the pinhole, crumb, and double-hydrometer test methods may disagree. The crumb test is a better indicator of dispersive soils than of non-dispersive soils (3).
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding establish...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6572 − 21
Standard Test Methods for
Determining Dispersive Characteristics of Clayey Soils by
1
the Crumb Test
This standard is issued under the fixed designation D6572; 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 (´) indicates an editorial change since the last revision or reapproval.
NOTE 1—In some cases, the results of the pinhole, crumb, and
1. Scope*
double-hydrometer test methods may disagree. The crumb test is a better
1.1 Two test methods are provided to give a qualitative
indicator of dispersive soils than of non-dispersive soils (3).
indication of the natural dispersive characteristics of clayey
1.6 Units—The values stated in SI units are to be regarded
soils: Method A and Method B.
as standard. No other units of measurement are included in this
1.1.1 Method A—Procedure for Natural Soil Crumbs de-
standard.
scribed in 10.1.
1.7 All observed and calculated values shall conform to the
1.1.2 Method B—Procedure for Remolded Soil Crumbs
guidelines for significant digits and rounding established in
described in 10.2.
Practice D6026.
1.2 The crumb test, while a good, quick indication of
1.7.1 Theproceduresusedtospecifyhowdataarecollected/
dispersive soil, should usually be run in conjunction with a
recorded or calculated in this standard are regarded as the
pinhole test and a double hydrometer test, Test Methods
industry standard. In addition, they are representative of the
D4647/D4647M and D4221, respectively. Since this test
significant digits that generally should be retained. The proce-
method may not identify all dispersive clay soils, other tests
dures used do not consider material variation, purpose for
such as, pinhole dispersion (Test Methods D4647/D4647M),
obtaining the data, special purpose studies, or any consider-
double hydrometer (Test Method D4221) and the analysis of
ations for the user’s objectives; and it is common practice to
porewaterextraction(TestMethodsD4542)maybeperformed
increase or reduce significant digits of reported data to be
individually or used together to help verify dispersion.
commensuratewiththeseconsiderations.Itisbeyondthescope
1.3 The crumb test has some limitations in its usefulness as
of this standard to consider significant digits used in analytical
anindicatorofdispersivesoil.Adispersivesoilmaysometimes
methods for engineering design.
give a non-dispersive reaction in the crumb test. Soils contain-
1.8 This standard does not purport to address all of the
ing kaolinite with known field dispersion problems, have
safety concerns, if any, associated with its use. It is the
2
shown non-dispersive reactions in the crumb test (1).
responsibility of the user of this standard to establish appro-
However, if the crumb test indicates dispersion, the soil is
priate safety, health, and environmental practices and deter-
probably dispersive.
mine the applicability of regulatory limitations prior to use.
1.4 These test methods are applicable only to soils where
1.9 This international standard was developed in accor-
the position of the plasticity index versus liquid limit plots dance with internationally recognized principles on standard-
(Test Methods D4318) falls on or above the “A” line (Practice
ization established in the Decision on Principles for the
D2487) and more than 12 % of the soil fraction is finer than Development of International Standards, Guides and Recom-
2-µm as determined in accordance with Test Method D7928.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.5 Oven-driedsoilshouldnotbeusedtopreparecrumbtest
specimens, as irreversible changes could occur to the soil
2. Referenced Documents
pore-water physicochemical properties responsible for disper-
3
2.1 ASTM Standards:
sion (2).
D653 Terminology Relating to Soil, Rock, and Contained
Fluids
1
These test methods are under the jurisdiction ofASTM Committee D18 on Soil
D1193 Specification for Reagent Water
and Rock and are the direct responsibility of Subcommittee D18.06 on Physical-
Chemical Interactions of Soil and Rock
Current edition approved May 1, 2021. Published May 2021. Originally
3
approved in 2000. Last previous edition approved in 2020 as D6572 – 20. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D6572-21. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
The boldface numbers in parentheses refer to the list of references at the end of Standards volume information, refer to the standa
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6572 − 20 D6572 − 21
Standard Test Methods for
Determining Dispersive Characteristics of Clayey Soils by
1
the Crumb Test
This standard is issued under the fixed designation D6572; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 Two test methods are provided to give a qualitative indication of the natural dispersive characteristics of clayey soils: Method
A and Method B.
1.1.1 Method A—Procedure for Natural Soil Crumbs described in 10.1.
1.1.2 Method B—Procedure for Remolded Soil Crumbs described in 10.2.
1.2 The crumb test, while a good, quick indication of dispersive soil, should usually be run in conjunction with a pinhole test and
a double hydrometer test, Test Methods D4647/D4647M and D4221, respectively. Since this test method may not identify all
dispersive clay soils, other tests such as, pinhole dispersion (Test Methods D4647/D4647M), double hydrometer (Test Method
D4221) and the analysis of pore water extraction (Test Methods D4542) may be performed individually or used together to help
verify dispersion.
1.3 The crumb test has some limitations in its usefulness as an indicator of dispersive soil. A dispersive soil may sometimes give
a non-dispersive reaction in the crumb test. Soils containing kaolinite with known field dispersion problems, have shown
2
non-dispersive reactions in the crumb test (1). However, if the crumb test indicates dispersion, the soil is probably dispersive.
1.4 These test methods are applicable only to soils where the position of the plasticity index versus liquid limit plots (Test Methods
D4318) falls on or above the “A” line (Practice D2487) and more than 12 % of the soil fraction is finer than 2-μm as determined
in accordance with Test Method D7928.
1.5 Oven-dried soil should not be used to prepare crumb test specimens, as irreversible changes could occur to the soil pore-water
physicochemical properties responsible for dispersion (2).
NOTE 1—In some cases, the results of the pinhole, crumb, and double-hydrometer test methods may disagree. The crumb test is a better indicator of
dispersive soils than of non-dispersive soils (3).
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1
These test methods are under the jurisdiction of ASTM Committee D18 on Soil and Rock and are the direct responsibility of Subcommittee D18.06 on Physical-Chemical
Interactions of Soil and Rock
Current edition approved March 1, 2020May 1, 2021. Published March 2020May 2021. Originally approved in 2000. Last previous edition approved in 20132020 as
ɛ2
D6572 – 13D6572 – 20. . DOI: 10.1520/D6572-20.10.1520/D6572-21.
2
The boldface numbers in parentheses refer to the list of references at the end of this standard.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6572 − 21
1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026.
1.7.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry
standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not
consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives;
and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.
It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.
1.8 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development o
...
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