ASTM D2166/D2166M-16
(Test Method)Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
Standard Test Method for Unconfined Compressive Strength of Cohesive Soil
SIGNIFICANCE AND USE
5.1 The primary purpose of the unconfined compression test is to quickly obtain a measure of compressive strength for those soils that possess sufficient cohesion to permit testing in the unconfined state.
5.2 Samples of soils having slickensided or fissured structure, samples of some types of loess, very soft clays, dry and crumbly soils and varved materials, or samples containing significant portions of silt or sand, or both (all of which usually exhibit cohesive properties), frequently display higher shear strengths when tested in accordance with Test Method D2850. Also, unsaturated soils will usually exhibit different shear strengths when tested in accordance with Test Method D2850.
5.3 If tests on the same sample in both its intact and remolded states are performed, the sensitivity of the material can be determined. This method of determining sensitivity is suitable only for soils that can retain a stable specimen shape in the remolded state.
Note 2: For soils that will not retain a stable shape, a vane shear test or Test Method D2850 can be used to determine sensitivity.
Note 3: 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. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers the determination of the unconfined compressive strength of cohesive soil in the intact, remolded, or reconstituted condition, using strain-controlled application of the axial load.
1.2 This test method provides an approximate value of the strength of cohesive soils in terms of total stresses.
1.3 This test method is applicable only to cohesive materials which will not expel or bleed water (water expelled from the soil due to deformation or compaction) during the loading portion of the test and which will retain intrinsic strength after removal of confining pressures, such as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands cannot be tested with this method to obtain valid unconfined compression strength values.
Note 1: The determination of the unconsolidated, undrained strength of cohesive soils with lateral confinement is covered by Test Method D2850.
1.4 This test method is not a substitute for Test Method D2850.
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.
1.5.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as the industry standard. In addition, they are representative of the significant digits that should generally 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 commensurate with these considerations. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering design.
1.6 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.
1.6.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)...
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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:D2166/D2166M −16
Standard Test Method for
1
Unconfined Compressive Strength of Cohesive Soil
This standard is issued under the fixed designation D2166/D2166M; 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* each system may not be exact equivalents; therefore, each
system shall be used independently of the other. Combining
1.1 This test method covers the determination of the uncon-
values from the two systems may result in non-conformance
fined compressive strength of cohesive soil in the intact,
with the standard.
remolded, or reconstituted condition, using strain-controlled
1.6.1 The gravitational system of inch-pound units is used
application of the axial load.
when dealing with inch-pound units. In this system, the pound
1.2 This test method provides an approximate value of the
(lbf) represents a unit of force (weight), while the unit for mass
strength of cohesive soils in terms of total stresses.
is slugs.The rationalized slug unit is not given, unless dynamic
1.3 Thistestmethodisapplicableonlytocohesivematerials (F = ma) calculations are involved.
1.6.2 It is common practice in the engineering/construction
which will not expel or bleed water (water expelled from the
soil due to deformation or compaction) during the loading profession to concurrently use pounds to represent both a unit
of mass (lbm) and of force (lbf). This implicitly combines two
portion of the test and which will retain intrinsic strength after
removal of confining pressures, such as clays or cemented separate systems of units; that is, the absolute system and the
gravitational system. It is scientifically undesirable to combine
soils. Dry and crumbly soils, fissured or varved materials, silts,
peats, and sands cannot be tested with this method to obtain the use of two separate sets of inch-pound units within a single
standard. As stated, this standard includes the gravitational
valid unconfined compression strength values.
system of inch-pound units and does not use/present the slug
NOTE 1—The determination of the unconsolidated, undrained strength
unit for mass. However, the use of balances or scales recording
of cohesive soils with lateral confinement is covered by Test Method
3
pounds of mass (lbm) or recording density in lbm/ft shall not
D2850.
be regarded as nonconformance with this standard.
1.4 This test method is not a substitute for Test Method
1.7 This standard does not purport to address all of the
D2850.
safety problems, if any, associated with its use. It is the
1.5 All observed and calculated values shall conform to the
responsibility of the user of this standard to establish appro-
guidelines for significant digits and rounding established in
priate safety and health practices and determine the applica-
Practice D6026, unless superseded by this standard.
bility of regulatory limitations prior to use.
1.5.1 Theproceduresusedtospecifyhowdataarecollected/
recorded and calculated in this test method are regarded as the
2. Referenced Documents
industry standard. In addition, they are representative of the
2
2.1 ASTM Standards:
significant digits that should generally be retained. The proce-
D653 Terminology Relating to Soil, Rock, and Contained
dures used do not consider material variation, purpose for
Fluids
obtaining the data, special purpose studies, or any consider-
D854 Test Methods for Specific Gravity of Soil Solids by
ations for the user’s objectives; and it is common practice to
Water Pycnometer
increase or reduce significant digits of reported data to com-
D1587 Practice for Thin-Walled Tube Sampling of Fine-
mensurate with these considerations. It is beyond the scope of
Grained Soils for Geotechnical Purposes
this test method to consider significant digits used in analysis
D2216 Test Methods for Laboratory Determination of Water
methods for engineering design.
(Moisture) Content of Soil and Rock by Mass
1.6 The values stated in either SI units or inch-pound units
D2488 Practice for Description and Identification of Soils
are to be regarded separately as standard. The values stated in
(Visual-Manual Procedure)
1
Thistestmethodisunder the jurisdiction ofASTM CommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
2
Compressibility of Soils. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2016. Published July 2016. Originally approved contact AST
...
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: D2166/D2166M − 13 D2166/D2166M − 16
Standard Test Method for
1
Unconfined Compressive Strength of Cohesive Soil
This standard is issued under the fixed designation D2166/D2166M; 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 This test method covers the determination of the unconfined compressive strength of cohesive soil in the intact, remolded,
or reconstituted condition, using strain-controlled application of the axial load.
1.2 This test method provides an approximate value of the strength of cohesive soils in terms of total stresses.
1.3 This test method is applicable only to cohesive materials which will not expel or bleed water (water expelled from the soil
due to deformation or compaction) during the loading portion of the test and which will retain intrinsic strength after removal of
confining pressures, such as clays or cemented soils. Dry and crumbly soils, fissured or varved materials, silts, peats, and sands
cannot be tested with this method to obtain valid unconfined compression strength values.
NOTE 1—The determination of the unconsolidated, undrained strength of cohesive soils with lateral confinement is covered by Test Method D2850.
1.4 This test method is not a substitute for Test Method D2850.
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026, unless superseded by this standard.
1.5.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as the
industry standard. In addition, they are representative of the significant digits that should generally 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 commensurate with these
considerations. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering
design.
1.6 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.
1.6.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)
represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F =
ma) calculations are involved.
1.6.2 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of
mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and the
gravitational system. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single
standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit for
3
mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft shall not be regarded
as nonconformance with this standard.
1.7 This standard does not purport to address all of the safety problems, 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
1
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
Compressibility of Soils.
Current edition approved May 15, 2013July 1, 2016. Published August 2013July 2016. Originally approved in 1963. Last previous edition approved in 20062013 as D2166
– 06.13. DOI: 10.1520/D2166_D2166M-13.10.1520/D2166_D2166M-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual
...
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