ASTM D6467-21e1

Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Fine-Grained Soils

SIGNIFICANCE AND USE
5.1 The ring shear test is suited to the relatively rapid determination of drained residual shear strength because of the short drainage path through the thin specimen, the constant cross-sectional area of the shear surface during shear, unlimited rotational displacement in one direction, and the capability of testing one specimen under different effective normal stresses to obtain clay particles that are oriented parallel to the direction of shear to obtain residual shear strength envelope.  
5.2 The apparatus allows a reconstituted specimen to be overconsolidated and presheared prior to drained shearing. Overconsolidation and preshearing of the reconstituted specimen significantly reduces the horizontal displacement required to reach a residual condition, and therefore, reduces soil extrusion, wall friction, and other problems (Stark and Eid, 1993)3. This simulates a preexisting shear surface along which the drained residual strength can be mobilized.  
5.3 The ring shear test specimen is annular so the angular displacement differs from the inner edge to the outer edge. At the residual condition, the shear strength is constant across the specimen so the difference in shear stress between the inner and outer edges of the specimen is negligible.
Note 1: Notwithstanding the statements on precision and bias contained in this test method: The precision of this test method 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 testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 Fine-grained soils in this Test Method are restricted to soils containing no more than 15 % fine sand (100 % passing the 425 μm (No. 40) sieve and no more than 15 % retained on the 75 μm (No. 200) sieve).A Summary of Changes section appears at the end of this standard.  
1.2 This test method provides a procedure for performing a torsional ring shear test under a drained condition to determine the residual shear strength of fine-grained soils. This test method is performed by shearing a reconstituted, overconsolidated, presheared specimen at a controlled displacement rate until the constant drained shear resistance is established on a single shear surface determined by the configuration of the apparatus.  
1.3 In this test, the specimen rotates in one direction until the constant or residual shear resistance is established. The amount of rotation is converted to displacement using the average radius of the specimen and multiplying it by numbers of degrees traveled and 0.0174.  
1.4 An intact specimen or a specimen with a natural shear surface can be used for testing. However, obtaining a natural slip surface specimen, determining the direction of field shearing, and trimming and aligning the usually non-horizontal shear surface in the ring shear apparatus is difficult. As a result, this test method focuses on the use of a reconstituted specimen to determine the residual strength. An unlimited amount of continuous shear displacement can be achieved to obtain a residual strength condition in a ring shear device.  
1.5 A shear stress-displacement relationship may be obtained from this test method. However, a shear stress-strain relationship or any associated quantity, such as modulus, cannot be determined from this test method because the height of the shear zone unknown, so an accurate or representative shear strain cannot be determined.  
1.6 The selection of effective normal stresses and determination of the shear strength parameters for design analyses are the responsibility of the professional or office requesting the test. Generally, three or more effective normal s...

General Information

• Status: Published
• Publication Date: 31-Aug-2021
• ICS: 13.080.20 - Physical properties of soils
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.05 - Strength and Compressibility of Soils

Relations

• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D854-23 - Standard Test Methods for Specific Gravity of Soil Solids by the Water Displacement Method
• Effective Date: 01-Nov-2023
• Refers: ASTM D2974-20 - Standard Test Methods for Determining the Water (Moisture) Content, Ash Content, and Organic Material of Peat and Other Organic Soils
• Effective Date: 15-Jan-2020
• Refers: ASTM D2974-20e1 - Standard Test Methods for Determining the Water (Moisture) Content, Ash Content, and Organic Material of Peat and Other Organic Soils
• Effective Date: 15-Jan-2020
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D2487-17 - Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
• Effective Date: 15-Dec-2017
• Refers: ASTM D2487-17e1 - Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
• Effective Date: 15-Dec-2017
• Refers: ASTM D2488-17 - Standard Practice for Description and Identification of Soils (Visual-Manual Procedures)
• Effective Date: 15-Jul-2017
• Refers: ASTM D4318-17e1 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• Effective Date: 01-Jun-2017
• Refers: ASTM D4318-17 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• Effective Date: 01-Jun-2017
• Refers: ASTM D7928-16 - Standard Test Method for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis
• Effective Date: 01-May-2016
• Refers: ASTM D7928-16e1 - Standard Test Method for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis
• Effective Date: 01-May-2016
• Refers: ASTM D2974-14 - Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils
• Effective Date: 01-Nov-2014
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014

Overview

ASTM D6467-21e1 is the internationally recognized standard test method for the Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Fine-Grained Soils. Developed by ASTM International, this test method outlines the procedure for measuring the drained residual shear strength of fine-grained soils, specifically those containing limited fine sand and larger particles. The method is essential for geotechnical engineering, enabling the assessment of soil behavior under long-term or repeated shearing conditions.

The ring shear test is suited for rapid and reliable determination of residual shear strength due to the short drainage path and constant cross-sectional shear area. By employing unlimited rotational displacement and preshearing capabilities, this test simulates real-world scenarios like slope failures and landslides, where soils have experienced substantial previous deformations.

Key Topics

• Test Method and Apparatus: The standard details how to prepare and test a reconstituted or intact soil specimen using an annular ring shear apparatus, allowing continuous shear displacement until a constant resistance (residual strength) is achieved. Effective normal stresses can be varied for a single specimen to produce a strength envelope.

• Soil Specimen Requirements: The soils tested are restricted to those with no more than 15% fine sand, all passing the 425 μm (No. 40) sieve, and limited retention on the 75 μm (No. 200) sieve. Both intact and reconstituted specimens can be used; however, reconstituted samples are preferred due to the difficulty of aligning natural shear surfaces.

• Drained Residual Shear Strength: The test is performed under fully drained conditions, crucial for determining the minimum constant resistance soil can offer along a fully developed failure surface. This value is used for design and stability analyses of slopes and embankments.

• Precision and Competence: Accurate results depend on the skill of personnel and the suitability of equipment. The method references ASTM Practice D3740 for agencies performing testing, emphasizing the need for competence and rigorous calibration.

Applications

The ASTM D6467 test method has critical applications in:

• Slope Stability Analysis: Used by engineers to assess landslide risks and design stable slopes by determining the lowest possible shear strength soils might exhibit under recurring displacement.
• Geotechnical Design: Essential for the safe design of embankments, earth dams, roadways, and other structures resting on or constructed with fine-grained soils.
• Forensic Geotechnical Investigations: Helps identify causes of soil failure in existing structures or natural slopes by replicating drained conditions and shear surfaces.
• Research and Education: Widely applied in soil mechanics research and higher education for understanding soil behavior under persistent shear stress.

Related Standards

To ensure comprehensive soil analysis and reporting, ASTM D6467-21e1 references several related standards, including:

• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids
• ASTM D4318: Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
• ASTM D2216: Test Methods for Laboratory Determination of Water Content of Soil and Rock by Mass
• ASTM D2487/D2488: Classification and Description of Soils
• ASTM D2435: Test Methods for One-Dimensional Consolidation Properties of Soils
• ASTM D3740: Practice for Minimum Requirements for Agencies Engaged in Testing of Soil and Rock

Practical Value

Implementing ASTM D6467-21e1 enables accurate, repeatable measurement of the residual shear strength of fine-grained soils, providing critical input for safe, cost-effective geotechnical engineering. By simulating the most adverse soil strength conditions, this test method empowers engineers to mitigate risk, ensure structural stability, and comply with regulatory and industry best practices in soil mechanics and slope stability design.

Standards Content (Sample)

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.
´1
Designation: D6467 − 21
Standard Test Method for
Torsional Ring Shear Test to Determine Drained Residual
Shear Strength of Fine-Grained Soils
This standard is issued under the fixed designation D6467; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—The standard was editorially updated in January 2022.
1. Scope* 1.6 The selection of effective normal stresses and determi-
nation of the shear strength parameters for design analyses are
1.1 Fine-grained soils in this Test Method are restricted to
the responsibility of the professional or office requesting the
soils containing no more than 15% fine sand (100% passing
test. Generally, three or more effective normal stresses are
the 425µm (No. 40) sieve and no more than 15% retained on
applied to a test specimen in a multi-stage test or a new
the 75µm (No. 200) sieve).
specimen can be used for each effective normal stress to
1.2 This test method provides a procedure for performing a
determine the drained residual failure envelope.
torsional ring shear test under a drained condition to determine
the residual shear strength of fine-grained soils. This test
1.7 The values stated in SI units are to be regarded as
method is performed by shearing a reconstituted,
standard. The values given in parentheses are provided for
overconsolidated, presheared specimen at a controlled dis-
information only and are not considered standard. The values
placement rate until the constant drained shear resistance is
given in parentheses are mathematical conversions to inch-
established on a single shear surface determined by the
pound units. Reporting of test results in units other than SI
configuration of the apparatus.
shall not be regarded as nonconformance with this standard.
1.3 In this test, the specimen rotates in one direction until
1.8 All measured and calculated values shall conform to the
the constant or residual shear resistance is established. The
guidelines for significant digits and rounding established in
amount of rotation is converted to displacement using the
Practice D6026 unless superseded by this standard.
average radius of the specimen and multiplying it by numbers
1.8.1 Theproceduresusedtospecifyhowdataarecollected/
of degrees traveled and 0.0174.
recorded or calculated in the standard are regarded as the
1.4 An intact specimen or a specimen with a natural shear
industry standard. In addition, they are representative of the
surface can be used for testing. However, obtaining a natural
significant digits that generally should be retained. The proce-
slip surface specimen, determining the direction of field
dures used do not consider material variation, purpose for
shearing,andtrimmingandaligningtheusuallynon-horizontal
obtaining the data, special purpose studies, or any consider-
shearsurfaceintheringshearapparatusisdifficult.Asaresult,
ations for the user’s objectives; and it is common practice to
this test method focuses on the use of a reconstituted specimen
increase or reduce significant digits of reported data to be
to determine the residual strength. An unlimited amount of
commensuratewiththeseconsiderations.Itisbeyondthescope
continuous shear displacement can be achieved to obtain a
of this standard to consider significant digits used in analysis
residual strength condition in a ring shear device.
methods for engineering design.
1.5 A shear stress-displacement relationship may be ob-
1.9 This standard does not purport to address all of the
tained from this test method. However, a shear stress-strain
safety concerns, if any, associated with its use. It is the
relationship or any associated quantity, such as modulus,
cannot be determined from this test method because the height responsibility of the user of this standard to establish appro-
of the shear zone unknown, so an accurate or representative priate safety, health, and environmental practices and deter-
shear strain cannot be determined.
mine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accor-
1 dance with internationally recognized principles on standard-
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and ization established in the Decision on Principles for the
Compressibility of Soils.
Development of International Standards, Guides and Recom-
Current edition approved Sept. 1, 2021. Published September 2021. Originally
ɛ1 mendations issued by the World Trade Organization Technical
approved in 1999. Last previous edition approved in 2013 as D6467–13 . DOI:
10.1520/D6467-21E01. Barriers to Trade (TBT) Committee.
*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
´1
D6467 − 21
2. Referenced Documents 3.2.6 indurated sediments, n—sediments hardened by sig-
2 nificant pressure and/or cementing agent to create a sedimen-
2.1 ASTM Standards:
tary rock such as shale.
D653Terminology Relating to Soil, Rock, and Contained
Fluids
4. Summary of Test Method
D854Test Methods for Specific Gravity of Soil Solids by
4.1 This test method consists of a consolidation and shear
Water Pycnometer
phase. The consolidation phase is accomplished by placing a
D2216Test Methods for Laboratory Determination ofWater
specimen in the annular specimen container, applying a prede-
(Moisture) Content of Soil and Rock by Mass
termined effective normal stress, usually in stages, through the
D2435Test Methods for One-Dimensional Consolidation
top loading platen, providing for wetting and draining of the
Properties of Soils Using Incremental Loading
specimen; consolidating the specimen under each of the
D2487Practice for Classification of Soils for Engineering
effectivenormalstresses;decreasingtheeffectivenormalstress
Purposes (Unified Soil Classification System)
to yield an overconsolidated specimen prior to preshearing for
D2488Practice for Description and Identification of Soils
both single and multi-stage tests. The shear phase is accom-
(Visual-Manual Procedures)
plished by preshearing the specimen by rotating the specimen
D2974Test Methods for Determining the Water (Moisture)
container at a slow and constant rate of shear deformation
Content, Ash Content, and Organic Material of Peat and
rotation against the top loading platen for at least one revolu-
Other Organic Soils
tion; allowing the specimen to equilibrate before drained
D3740Practice for Minimum Requirements for Agencies
shearing, applying a slow and constant rate of shear deforma-
Engaged in Testing and/or Inspection of Soil and Rock as
tion rotation during shearing; and measuring the torque/
Used in Engineering Design and Construction
shearing force, vertical displacement, and rotation displace-
D4318Test Methods for Liquid Limit, Plastic Limit, and
ment until a constant value of shearing resistance is reached.
Plasticity Index of Soils
D6026Practice for Using Significant Digits and Data Re- 5. Significance and Use
cords in Geotechnical Data
5.1 The ring shear test is suited to the relatively rapid
D6913Test Methods for Particle-Size Distribution (Grada-
determination of drained residual shear strength because of the
tion) of Soils Using Sieve Analysis
short drainage path through the thin specimen, the constant
D7928Test Method for Particle-Size Distribution (Grada-
cross-sectionalareaoftheshearsurfaceduringshear,unlimited
tion) of Fine-Grained Soils Using the Sedimentation
rotational displacement in one direction, and the capability of
(Hydrometer) Analysis
testing one specimen under different effective normal stresses
E11Specification forWovenWireTest Sieve Cloth andTest
toobtainclayparticlesthatareorientedparalleltothedirection
Sieves
of shear to obtain residual shear strength envelope.
5.2 The apparatus allows a reconstituted specimen to be
3. Terminology
overconsolidated and presheared prior to drained shearing.
3.1 Definitions—For definitions of common technical terms
Overconsolidation and preshearing of the reconstituted speci-
used in this standard, refer to Terminology D653.
men significantly reduces the horizontal displacement required
3.2 Definitions of Terms Specific to This Standard:
to reach a residual condition, and therefore, reduces soil
3.2.1 consolidated, adj—soil specimen condition after pri-
extrusion, wall friction, and other problems (Stark and Eid,
mary consolidation under a specific effective normal stress.
1993) .This simulates a preexisting shear surface along which
the drained residual strength can be mobilized.
3.2.2 presheared, adj—soil specimen condition after shear-
ingtoatleastonerevolutionoftheringinthedirectionofshear
5.3 The ring shear test specimen is annular so the angular
to create a failure surface prior to drained shearing.
displacement differs from the inner edge to the outer edge. At
the residual condition, the shear strength is constant across the
3.2.3 residual shear force, n—the residual shear force is the
specimen so the difference in shear stress between the inner
average shear force being applied to the specimen when the
and outer edges of the specimen is negligible.
shear resistance neither increases nor decreases with continued
shear displacement.
NOTE 1—Notwithstanding the statements on precision and bias con-
tained in this test method: The precision of this test method is dependent
3.2.4 residual shear strength, n—the minimum constant
onthecompetenceofthepersonnelperformingitandthesuitabilityofthe
resistance of soil to shear along a fully developed failure
equipment and facilities used. Agencies that meet the criteria of Practice
surface and equals the residual shear force divided by the
D3740 are generally considered capable of competent testing. Users of
cross-sectional area of the specimen.
this test method are cautioned that compliance with Practice D3740 does
not ensure reliable testing. Reliable testing depends on several factors;
3.2.5 drained residual strength state, n—thestateatwhicha
Practice D3740 provides a means of evaluating some of those factors.
soil exhibits residual shear strength and shear stress – shear
6. Apparatus
displacement relationship becomes almost horizontal.
6.1 Shear Device, to hold the specimen securely between
two porous discs. The shear device provides a mean for
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Stark,T.D. and Eid, H.T. (1993). “Modified Bromhead Ring ShearApparatus,”
the ASTM website. Geotechnical Testing Journal, ASTM, Vol. 16, No. 1, March, 1993, pp. 100-107.
´1
D6467 − 21
applying an effective normal stress to the faces of the 6.4.2 The hydraulic conductivity of the discs shall be
specimen,formeasuringchangesinthicknessofthespecimen, substantially greater than that of the soil, but shall be textured
forpermittingdrainageofwaterthroughtheporousdiscsatthe fine enough to prevent excessive intrusion of the soil into the
top and bottom boundaries of the specimen, and for submerg- poresofthedisc.Theporousdiscsshallbecleanandfreefrom
ing the specimen in water. The device is capable of applying a cracks, chips, and nonuniformities. New porous discs should
torque to the specimen along a shear surface parallel to the be boiled for at least 10 minutes and left in the water to cool to
facesofthespecimen.Anumberofdifferentringsheardevices ambient temperature before use. Immediately after each use,
arecommerciallyavailable,inpractice,orarebeingdeveloped clean the porous discs with a nonabrasive brush and boil to
so a general description of a ring shear device is presented remove clay particles that may reduce their permeability.
without schematic diagrams. The location of the shear surface Alternatively, ultrasonic cleaning could be used to clean the
depends on the configuration of the specimen container and/or porous disc.
apparatus.As a result, the shear surface may be located near a
NOTE 2—Exact criteria for porous disc texture and hydraulic conduc-
soil/porous disc interface or at the mid-height of the specimen
tivity have not been established. For normal soil testing, medium-grade
–4 –3
if an upper ring can be separated from a bottom ring as is done
discs with a hydraulic conductivity of about 5.0 × 10 to 1.0 × 10 cm/s
(0.5 to 1.0 × 10 ft/year) are appropriate for testing fine-grained soils.
in a direct shear box. The device shall have low friction along
the inner and outer walls of the specimen container developed
6.5 Loading Devices:
during shearing. Friction may be reduced by having the shear
6.5.1 Device for Applying and Measuring the Normal
surface occur at the top of the specimen container and
Force—The device shall be capable of rapidly applying and
modifying the specimen container walls with low-friction
maintaining the normal force to within 61% of the specified
material. The frames that hold the specimen shall be suffi-
force.
ciently rigid to prevent their distortion during consolidation
6.5.2 Device for Shearing the Specimen—This device shall
and shearing. The various parts of the shear device shall be
be capable of shearing the specimen at a uniform rate of
made of a material such as stainless steel, bronze, or coated
rotation, without difference in shear displacement rate due to
aluminum that is not subject to corrosion by moisture or
friction.The rate to be applied depends upon the consolidation
substanceswithinthesoil.Dissimilarmetals,whichmaycause
characteristics of the soil (see 9.6.1). The rate is usually
galvanic action, are not permitted.
maintained with an electric motor and gear box arrangement.
6.2 Specimen Container, a device containing an annular
6.6 Shear Force Measurement Device, two proving rings,
cavity for the soil specimen with an inside diameter not less
load cells, in combination with a lever arm or a torque
than 50 mm (2 in.) and an inside to outside diameter ratio not
transducer accurate to measure a force of 0.1 N (0.03 lbf).
lessthan0.6.Thecontainerhasprovisionsfordrainagethrough
6.7 Water Bath, container for the specimen container and
the top and bottom. The initial specimen thickness, before
water needed to inundate the specimen.
consolidation and preshearing, is not less than 5 mm (0.2 in.).
Themaximumparticlesizefornon-induratedsoilsislimitedto
6.8 Controlled High-Humidity Environment—For preparing
10% of the initial specimen height as stated in the test
the specimen, such that the water (moisture) content gain or
specimen description.
loss during specimen rehydration is minimized.
6.3 Torque Arm/Loading Platen Assembly, may have differ-
6.9 Vertical Deformation Indicators—Dial gauge, or other
ent bearing stops for the proving rings, load cells, or force or
suitable device, capable of measuring the change in thickness
torque transducers to provide different options for the torque
of the specimen, with a sensitivity of 0.0025 mm (0.0001 in.).
measurement.
6.10 Rotational Horizontal Deformation Indicator—Ring
6.4 Porous Discs, two porous metal discs such as, bronze,
shear device having gauge or etched scale on circumference of
stainlesssteel,carborundum,orcorundum,mountedonthetop
the ring base to measure the degrees traveled, and thus the
loadingplatenandthebottomofthespecimencontainercavity
shear displacement, or other methods capable of obtaining a
to allow drainage from the soil specimen along the top and
sensitivity of at least 1.0 mm or 1.5°.
bottom boundaries. The outer and inner diameters of the discs
6.11 Equipment for Determination of Water Content, in
shall be 0.1 mm (0.004 in.) less, and greater than those of the
accordance with Test Method D2216.
specimen annular cavity, respectively.
6.4.1 The porous discs must have good contact between the
6.12 Sieves—425µm (No.40) and 75µm (No.200) sieves
disc and the soil and a surface or pattern that develops a strong
conforming with Specification E11.
interlockwiththesoilspecimentoaidintransferofshearstress
6.13 Miscellaneous Equipment,includingtimingdevicethat
to the top and bottom boundaries of the specimen. The discs
can be read to seconds, site-specific, distilled or demineralized
must be sufficiently serrated to develop a strong interlock with
water, mortar, pestle, spatulas, razor blades, straightedge, data
the soil specimen so shearing occurs in the soil and not at the
sheet or acquisition system to monitor the test, and so forth.
soil-disc interface. If failure occurs at the soil-disc interface,
the resulting resistance will be extremely low. This interlock 6.14 Wall Friction Reduction—Wall friction may be signifi-
can be accomplished by minimizing the disc surface area in cantduringtheshearingprocesscausinganoverestimateofthe
contact with the soil and having part of the disc penetrate into residual strength, therefore, minimization of wall friction is
the specimen. The serration must have a depth of between 10 necessary. For example, if the specimen container consists of a
and 15% of the specimen height before shearing. single piece of metal, the amount of wall friction depends on
´1
D6467 − 21
the magnitude of top platen settlement into the specimen 7.7 Reconstituted specimens of highly indurated fine-
container, type of soil, and material lining of the specimen grained specimen (that is, overconsolidated clays, mudstones,
container walls. In this type of specimen container, the thick- claystones, and shales) may be prepared by ball-milling an
ness of soil trapped between the inner and outer walls of the air-dried representative sample and passing it through the U.S.
specimen container and the upper porous disc should be Standard 75µm (No. 200) sieve. Ball-milling facilitates disag-
minimized.Ifthespecimencontainercanbeseparatedintotwo gregation of the clay particles and reduces the shear displace-
pieces, the opening between the upper and lower halves must ment required to achieve a residual strength condition
be wide enough to prevent particles from becoming trapped in (LaGatta, 1970 ). If ball-milling is not used and other disag-
the opening and that shearing occurs at this opening. Other gregation methods are used, that is, soaking (Test Method
techniques also can be used to reduce wall friction. D4318),blenderizing,discmilling,andmortarandpestle(Test
MethodD4318),greatersheardisplacementwillberequiredto
7. Sampling and Test Specimens
disaggregate the mudstone, claystone, and shale particles and
achieve a residual strength condition in the apparatus because
7.1 The sample used for specimen preparation is to be
they are not as effective as ball-milling in disaggregating
sufficiently large so that a ring shear specimen and specimens
highly indurated materials. The additional shear displacement
for index property tests, for example, Atterberg Limits (Test
can be large and create testing problems such as soil extrusion
Method D4318), particle size distribution (Test Method
and wall friction that can result in unconservative residual
D6913), and clay-size fraction (Test Method D7928), can be
strength.Non-induratedsoilsmustnotbeball-milledbecauseit
prepared. The specimen being tested should be at or near full
will change the gradation of the soil. Non-indurated soils must
saturation.
be passed through the 425µm (No.40) sieve as required for
7.2 The liquid limit, plastic limit, plasticity index (Test
Atterberg Limits (Test Method D4318).
Method D4318), and clay-size fraction (Test Method D7928)
ofthespecimensaremeasuredusingthesameprocessedsoilas
7.8 Care is to be taken during disaggregation and mixing
used for shear testing. operations to avoid introducing impurities into the sample.
7.3 If an intact specimen is desired, the sample obtained
8. Calibration
from the field shear surface could be trimmed to produce an
annular specimen. This must be done in such a way that
8.1 The calibration is to determine the deformation of the
moisture loss or gain is minimized. A preexisting field shear
apparatus, exclusive from the specimen, when subjected to the
surface may consist of small seams of clayey material sur-
consolidationload.Becauseonlydeformationcausedbyspeci-
roundedbymaterialwithacoarsergradation.Ifso,tosimulate
men consolidation will be reported for complete tests the
fieldpreexistingshearingconditionsonlytheclayeyshearzone
apparatus deformation at each consolidation load must be
material is to be tested and not the coarser surrounding
subtracted from the observed deformations during a test.
material.
8.2 Theleverarmusedtoapplytheconsolidationloadmust
7.4 A reconstituted non-indurated fine-grained specimen
be horizontal at all times so as to maintain the loading ratio of
may be prepared by disaggregating an air-dried representative
10:1 for each load added to the hanger system.
sample and passing it through the 425µm (No.40) sieve or an
8.3 Theleverarmshallalsobeadjustedsuchthatitdoesnot
appropriate sieve, for example, opening size less than or equal
apply any significant load to the specimen when resting and
to 10% (0.5 mm) of the initial specimen height. Air dried
only the load applied to the hanger system is applied to the
method must not be used for highly plastic soils, tropical soils,
specimen.
and organic soils based on Test Methods D2974. Soil with
more than 25.0% organic content based on Test Methods
8.4 Assemble the ring-shear device with the porous discs
D2974 is to be reconstituted without drying.
and a metal calibration disc or plate of a thickness approxi-
mately equal to the desired test specimen and slightly smaller
7.5 After processing, the reconstituted sample could be
in width. The metal calibration disc shall have parallel end
mixed with site specific water/fluid or distilled water until a
surfaces finished to a high degree of precision, and be clean
water (moistur
...