ASTM D6773-22

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: D6773 − 22
Standard Test Method for
Bulk Solids Using Schulze Ring Shear Tester
This standard is issued under the fixed designation D6773; 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.
1. Scope* 1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the apparatus and procedures
responsibility of the user of this standard to establish appro-
for measuring the unconfined yield strength of bulk solids
priate safety, health, and environmental practices and deter-
during both continuous flow and after storage at rest. In
mine the applicability of regulatory limitations prior to use.
addition, measurements of internal friction, bulk density, and
1.7 This international standard was developed in accor-
wall friction on various wall surfaces are included.
dance with internationally recognized principles on standard-
1.2 This test method covers operation of the manually-
ization established in the Decision on Principles for the
controlledSchulzeRingShearTester.Anautomatedversionof
Development of International Standards, Guides and Recom-
this tester is also available. Its method of testing bulk solids is
mendations issued by the World Trade Organization Technical
similar in principle to that described in this test method.
Barriers to Trade (TBT) Committee.
1.3 The most common use of this information is in the
2. Referenced Documents
design of storage bins and hoppers to prevent flow stoppages
2.1 ASTM Standards:
due to arching and ratholing, including the slope and smooth-
D653Terminology Relating to Soil, Rock, and Contained
ness of hopper walls to provide mass flow. Parameters for
Fluids
structural design of such equipment may also be derived from
D2216Test Methods for Laboratory Determination ofWater
this data. Another application is the measurement of the
(Moisture) Content of Soil and Rock by Mass
flowability of bulk solids, for example, for comparison of
D3740Practice for Minimum Requirements for Agencies
different products or optimization.
Engaged in Testing and/or Inspection of Soil and Rock as
1.4 All observed and calculated values shall conform to the
Used in Engineering Design and Construction
guidelines for significant digits and rounding established in
D4753Guide for Evaluating, Selecting, and Specifying Bal-
Practice D6026.
ances and Standard Masses for Use in Soil, Rock, and
1.4.1 Theproceduresusedtospecifyhowdataarecollected/
Construction Materials Testing
recorded or calculated in this standard are regarded as the
D6026Practice for Using Significant Digits and Data Re-
industry standard. In addition, they are representative of the
cords in Geotechnical Data
significant digits that generally should be retained. The proce-
D6128Test Method for Shear Testing of Bulk Solids Using
dures used do not consider material variation, purpose for
the Jenike Shear Tester
obtaining the data, special purpose studies, or any consider-
E177Practice for Use of the Terms Precision and Bias in
ations for the user’s objectives: and it is common practice to
ASTM Test Methods
increase or reduce significant digits of reported data to be
E691Practice for Conducting an Interlaboratory Study to
commensuratewiththeseconsiderations.Itisbeyondthescope
Determine the Precision of a Test Method
of this standard to consider significant digits used in analysis
methods for engineering design. 3. Terminology
3.1 Definitions—For definitions of common technical terms
1.5 Units—The values stated in SI units are to be regarded
in this standard, refer to Terminology D653.
as standard. No other units of measure are included in this
standard.
4. Summary of Test Method
4.1 A representative specimen of bulk solid is placed in a
shear cell of specific dimensions.
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.24 on Characterization
and Handling of Powders and Bulk Solids. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 15, 2022. Published January 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2002. Last previous edition approved in 2016 as D6773–16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6773-22. the ASTM website.
*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
D6773 − 22
4.2 When running an instantaneous or time shear test, a 6.2 Thedrivingaxle5(withdetachableplasticcap6)causes
normal load is applied to the cover, and the specimen is theshearcell4torotate.Thedriverpinsattheundersideofthe
presheared until a steady state shear value has been reached. shear cell must set in the toothed wheel at the driving axle 5 to
The shear stress is then immediately reduced to zero. enable a close connection between shear cell and driving axle.
The driving axle is driven by an electric motor and can rotate
4.3 An instantaneous test is run by shearing the specimen
to the right or to the left. In order to shear the bulk solid
under a reduced normal load until the shear force goes through
specimen, the driving axle 5 along with the shear cell 4 rotate
a maximum value and then begins to decrease.
clockwise (as seen from the top). The electric motor is
4.4 A time shear test is run similarly to an instantaneous
controlled from the front panel 35 at the front side of casing 2
sheartest,exceptthatthespecimenisplacedinaconsolidation
(Fig. 3). The motor and drive system cause the shear cell to
bench for the specified time between the preshear and shear
rotate at a speed adjustable between 0.007 and 0.13 rad/min.
steps.
6.3 The shear cell lid 7 as well as the bottom of the shear
4.5 A wall friction test is run by sliding the specimen over
cell 4 has bent bars made of stainless steel (Fig. 4) to prevent
a coupon of wall material and measuring the frictional resis-
slipping of the bulk solid at the lid or the bottom of the shear
tance as a function of normal, compressive load.
cell.
NOTE 2—The standard cell has 20 bars, each of which is 4 mm tall
4.6 A wall friction time test involves sliding the specimen
(h =4 mm, Fig. 7).
Mit
overthecouponofwallmaterial,stoppingandleavingtheload
6.4 The crossbeam 8 sits on the lid 7 and is fixed with two
on the specimen for a predetermined period, and then sliding it
knurledscrews9.Thecrossbeam8hasseveralfunctions:Inthe
again to see if the shearing force has changed.
center of the crossbeam 8 is a fixed axis 10 with a hook to
5. Significance and Use append the hanger 11 (in Figs. 3 and 4 only the handle of the
hangerstandingoutfromthedrivingaxlecanbeseen).Rollers
5.1 Reliable, controlled flow of bulk solids from bins and
attheendsofthecrossbeamandtheremovableguiderollers12
hoppers is essential in almost every industrial facility.
prevent movement of lid 7 from the centered position.
Unfortunately, flow stoppages due to arching and ratholing are
common. Additional problems include uncontrolled flow 6.5 A hook 14 at the upper end of the axis 10 of the
(flooding) of powders, segregation of particle mixtures, usable crossbeam 8 is fastened to the balance arm 15. This arm along
capacitywhichissignificantlylessthandesigncapacity,caking with counterbalance 29 (Fig. 6) serves to compensate for the
and spoilage of bulk solids in stagnant zones, and structural masses of lid 7, crossbeam 8, hanger 11, and tie rods 13. The
failures. counterbalance 29 is found at the rear side of the balance arm
15.
5.2 By measuring the flow properties of bulk solids, and
6.6 A digital displacement indicator 31 (Fig. 8) is used for
designing bins and hoppers based on these flow properties,
most flow problems can be prevented or eliminated (1). the measurement of the height of the bulk solid specimen.
6.7 Bolts at the ends of the crossbeam 8 are used to append
5.3 For bulk solids with a significant percentage of particles
the tie rods 13. Therefore, a circular hole is at one end of each
(typically,onethirdormore)finerthanabout6mm( ⁄4in.),the
tierod13.Theoppositeendisprovidedwithanelongatedhole
unconfined yield strength is governed by the fines (−6 mm
for suspending in the adjustable seating 16 attached to the load
fraction). For such bulk solids, strength and wall friction tests
beam 17.
may be performed on the fine fraction only.
NOTE 1—The quality of the result produced by this standard is
6.8 The rotation of the lid 7 is prevented by the tie rods 13
dependent on the competence of personnel performing it, and the
which transfer the tensile force to the load beams 17.
suitability of the equipment and facilities used. Agencies that meet the
criteria of Practice D3740 are generally considered capable of competent
6.9 The bottom part of the hanger 11, which hangs on the
and objective testing/sampling/inspection/etc. Users of this standard are
crossbeam 8 and serves for exerting a normal load N on the
cautioned that compliance with Practice D3740 does not in itself ensure
bulksolid,islocatedwithinthebase1(Fig.1).Thehangerhas
reliable results. Reliable results depend on many factors; Practice D3740
acircularplate19atitslowerendforholdingtheappliedmass
providesameansofevaluatingsomeofthosefactors.PracticeD3740was
developed for agencies engaged in the testing or inspection (or both) of
pieces.
soil and rock. As such it is not totally applicable to agencies performing
6.10 For control of the motor drive a front panel 35 (Fig. 3)
this standard. However, users of this standard should recognize that the
is at the front side of the casing 2.
framework of Practice D3740 is appropriate for evaluating the quality of
an agency performing this standard. Currently there is no known quali-
6.11 The load beams 17 are connected parallel. Each load
fying national authority that inspects agencies that perform this standard.
beam must be capable of measuring a force up to 200 N with
a precision of 0.02% of full scale. Thus, the total measuring
6. Apparatus
range,whichistwicethemeasuringrangeofoneloadbeam,is
6.1 The Schulze Ring Shear Tester (Figs. 1-6) is composed
400 N. The signal from the force transducer is conditioned by
of a base 1 and a casing 2. The casing 2 contains the driving
an amplifier and shown on a recorder. (Warning—To avoid
and measuring units and carries the working table38.
overloading of the load beams, the indicated maximum normal
load must not be exceeded.)
6.12 For the Schulze Ring ShearTester RST-01.01 different
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. shear cells are available. The dimensions of the Standard cell
D6773 − 22
FIG. 1 Ring Shear Tester (overall view)
and a smaller cell can be taken from Table 2 and Fig. 7. For consolidationasshownintheleftpartofFig.9.Thelowerend
special purposes (for example, reduced internal volume) other of the loading rod Z4 is equipped with a central tip.
dimensions are also available. The following table provides a
6.13.3 The transparent cylindrical plastic cap Z3, when
rough indication of the applicability of various cell sizes based
pressedonplateZ2,protectsthespecimensfromthesurround-
on maximum particle size of the bulk solid (monodisperse =
ing atmosphere (for example, to reduce changes of the mois-
narrow particle size distribution, for example, plastics pellets,
ture(water)ofthebulksolidspecimens).ThiscapZ3isjoined
grain). Values in parentheses are valid if particles are not
to the loading rod Z4 through a rubber bellows Z8.
brittle.
6.13.4 At the upper end of the loading rod Z4 a disk Z5 is
maximum particle size, x fastened for supporting applied mass pieces by which the
max
Shear cell type monodisperse broad distribution, 0 .
vertical load for time consolidation is applied.
x
max
6.13.5 The fixing screw Z6 serves for the fixation of the
M 5 mm 10 mm
S 2.5 mm 5 mm
loading rod Z4 in the upper position (Fig. 9, on the right).
MV10 1 (1.5) mm 2 (3) mm
SV10 0.75 (1) mm 1.5 (2) mm 6.14 The wall friction shear cells allow the measurement of
wall yield loci from which wall friction angles can be calcu-
6.13 The time consolidation bench serves for the storage of
lated.
shear cells with bulk solid specimens under load.
6.14.1 Thebottomring48ofthewallfrictionshearcell(see
6.13.1 Thetimeconsolidationbench(Fig.9)iscomposedof
Fig. 10) contains the wall material coupon to be tested.
a frame Z1, on which are fastened three supporting plates Z2.
One small shear cell (type S, volume approx. 200 cm ) can be 6.14.2 To prevent any relative circumferential displacement
placed on each plate. The shape of the plate Z2 centers the between the bottom ring 48 and the wall material coupon, four
shear cell. drivingpins50areinstalledattheouterwallofthebottomring
6.13.2 Through the central depression of the time consoli- 48. The annular wall material coupon has to be provided with
dation crossbeam 26 the normal load is exerted during time notches for these driving pins so that bottom ring and wall
D6773 − 22
FIG. 2 Shear Cell (in principle)
ance 29 on the balance arm.
material coupon are interlocked. The required dimensions of
the wall material coupon are shown in Fig. 11.
7.2.1.1 After unscrewing the knurled screw, which is the
6.14.3 Thelid49(Fig.12)hasbentbarsfromstainlesssteel
major part of the movable mass 30, shift the movable mass 30
to prevent slipping of the bulk solid at the lid of the shear cell.
along the balance arm, if necessary, for more precise adjust-
Additionally, the lid of a wall friction shear cell is provided
ment of the force caused by the counterbalance mass.
withdownwardsprotrudingedgesattheinnerandouterradius.
NOTE 5—When the counterbalance mass is well adjusted, the lid,
6.14.4 The dimensions of the wall friction shear cell are
crossbeam, tie rods, and hanger do not press on the bulk solid; that is, the
shown in Table 1 and Fig. 13.
vertical stress at the surface of the bulk solid is equal to zero.
6.15 A spatula having a rigid, sharp, straight blade at least
7.2.2 Adjust the seatings 16 to level the lid 7.
50%longerthanthewidthoftheannulusoftheshearcell,and
7.2.3 Adjust the four adjustable stands 3 on base 1 (Fig. 5)
at least 20 mm wide, is needed.
to level the Ring Shear Tester.
7.2.4 Unscrew the fixing screw sufficiently so as to be able
6.16 Alaboratory balance having a maximum capacity of at
tomovetheloadingrodupwardsordownwards.Intheloading
least 5 kg with a precision of 0.01% or better is required.
position (Fig. 9, on the left) the fixing screw must remain
7. Specimen Preparation
unscrewed.
7.2.5 Beforestartingwithtimeconsolidationmeasurements,
7.1 The laboratory used for powder testing must be free of
make sure that the time consolidation bench is level. Use the
vibrations caused by traffic or heavy machinery. Ideally, the
four adjustable feet Z7 (Fig. 9), if necessary
room is temperature and humidity controlled, or, if this is not
possible, maintain it at nearly constant ambient conditions.
7.3 Filling the Cell (Fig. 14):
Direct sunlight, especially on the time consolidation bench, is
7.3.1 Fill the shear cell 4 uniformly in small horizontal
to be avoided.
layers by a spoon or spatula without applying force to the
NOTE 3—Temperature- and humidity-sensitive materials may need to
surface of the material until the cell is slightly overfilled with
be tested at different temperatures and moisture (water) contents, because
material. Fill the cell in such a way as to make sure that there
thisoftenhappensinindustrialenvironments.Thelaboratoryenvironment
are no voids within it.
must approximate production for meaningful testing.
7.3.2 Remove excess material in small quantities by scrap-
7.2 Setup:
ingoffwithablade1untilflushwiththetopoftheannulus.At
7.2.1 Shiftthemovablecounterbalance29alongthebalance
first, scrape the blade counterclockwise across the ring one or
arm to adjust the force caused by the counterbalance mass.
two times in a zigzag motion. Then, scrape the blade around
NOTE 4—The fixation screw 18 (knurled screw) fixes the counterbal- the annulus counterclockwise, as shown in Fig. 14a, whereby
D6773 − 22
FIG. 3 Ring Shear Tester (upper part)
the blade is inclined by an angle α=15 to 30° to the radial 7.4.1 When measuring the friction between the particulate
direction.Holdthebladeverticallyortiltedbyafewdegreesto
solid and a coupon of silo wall material in a wall friction test,
the vertical (angle β=0° to 10°) as shown in Fig. 14b. Do not
add spacers and a coupon of wall material to the shear cell
exert a downward force on the material with the blade.
bottom ring. Shear the specimen contained in bottom ring over
7.3.3 If coarse particles are present, scraping may tear them
the wall material coupon under different wall normal stresses
fromthesurfaceandalterthestructure.Insuchcasesitisbetter
σ and measure the resulting wall shear stresses τ .
w w
to attempt to fill the cell so that the material surface is flush
7.4.2 Selection of Wall Friction Normal Stress Levels:
with the annulus after filling.
7.4.2.1 Select six wall friction normal stress levels σ to
w1
7.3.4 If necessary, clean the outside of the shear cell. Then
σ whereσ isthesmallestnormalstress.Thelargestnormal
w6 w1
determine the mass of the shear cell with contents. Note the
stress σ must be approximately equal to the major principal
total mass m . w6
tot
stress σ of the second preshear normal stress, σ . The
1,2 p,2
7.4 Wall Friction:
D6773 − 22
FIG. 4 Upper Part of the Ring Shear Tester, Shear Cell Removed
smallest normal stress σ will normally include the hanger inapositionturnedafewdegreescounterclockwisetoitsshear
w1
without applied masses.
position(shearposition:longitudinalaxisofthecrossbeam8is
7.4.3 Wall Coupon and Material Specimen Preparation: perpendiculartothefrontedgeofthecasing2).Directtheopen
7.4.3.1 Wash the wall material coupon and dry thoroughly
sideofthehook25inthecenterofthecrossbeam8totheright.
before the test. Do not touch the surface after washing with
Locate handle 24 of the hanger 11 on the right side of
bare hands.
crossbeam 8 (in analogy to Fig. 16).
7.4.3.2 Insert the spacer rings 51 and the wall material
7.4.3.10 Put the tie rods 13 on both the bolts at the ends of
coupon in the bottom ring 48 (Fig. 10). The distance between
crossbeam 8 (circular holes of tie rods 13) and the seatings 16
upper edge of the bottom ring 48 and upper surface of the wall
at the load beams 17 (long hole of the tie rod 13).
material coupon must total about 8 to 10 mm.
(1)Ensure that the tie rods 13 have some clearance in the
seatings 16; that is, the tie rods must not be stressed at that
NOTE 6—The thickness of each spacer ring is 2 mm.
stage. Important: If it is not possible to connect the tie rods as
7.4.3.3 Determine the mass of the bottom ring 48 with
described above, do not move the lid manually! This would
content (note total mass m ).
wall
influence the test result. Only use the motor drive to turn the
7.4.3.4 Connect crossbeam 8 and lid 49 using the knurled
shear cell with the lid in a position where it is possible to
screws 9.
connect the tie rods to the load beams.
7.4.3.5 Fill the bottom ring 48 with the bulk solid to be
tested. See 7.3. 7.4.3.11 Append hanger 11 at hook 25 on the lower side of
7.4.3.6 If necessary, clean the bottom ring 48 from outside. crossbeam 8.
Then determine the mass of the bottom ring 48 with content
7.4.3.12 Carefully put appropriate applied mass pieces on
(note total mass m ).
W,tot the circular plate 19 of the hanger.
7.4.3.7 Ascertain that the power supply is switched on.
NOTE 7—The total mass of the applied mass pieces on the hanger must
7.4.3.8 Put the filled bottom ring 48 on driving axle 5 (in
be less than or equal to the maximum normal load to be used for the wall
analogy to Fig. 15). The driver pins at the underside of the
friction measurement.
shear cell must engage in the toothed wheel at the driving axle
5. 7.4.3.13 Remove hook 14, which is connected to the bal-
ance arm, from its off-position mounting 32 and append it to
7.4.3.9 Carefully place the lid 49 concentrically on the
bottom ring 48 on the bulk solid specimen. The lid 49 must be the central axis 10 (in analogy to Fig. 16).To do this, the front
D6773 − 22
FIG. 5 View on the Reverse Side of the Ring Shear Tester
endofthebalancearmmustbepulleddownattheblackhandle 8.1.1.2 Put the filled shear cell 4 on the driving axle 5 (Fig.
46 provided for this (the handle is not shown in all figures; see 15). Make sure that the driver pins on the underside of the
Fig. 6). shear cell engage the toothed wheel of the driving axle 5.
(1)If the lid sinks down very much, the lower edge of the
8.1.1.3 Select the first preshear normal stress σ on the
p,1
lid may touch directly the upper surface of the wall material
basisofthebulkdensityofthetestmaterial,inaccordancewith
coupon, thus causing incorrect measurement results. If this
the following table:
happens, remove the shear cell from the tester, remove the lid
ρ (kg/m ) σ (kPa)
b p,1
from the bottom ring, and add additional bulk solid into the < 300 approximately 1.5
300 to 800 approximately 2.0
bottom ring following procedure starting at 7.4.3.5.
800 to 1600 approximately 2.5
7.4.3.14 Check the adjustment of the rotational velocity
1600 to 2400 approximately 3.0
(front panel 35). The circumferential velocity at the mean
> 2400 approximately 4.0
specimen diameter must be 1 to 2 mm/min.
8.1.1.4 Follow 8.1.1.5 – 8.1.1.10 only if the normal load at
preshear is greater than 15 N. Otherwise go to 8.1.1.12.
8. Procedure
NOTE8—Thelatterprocedureisnecessarysoastonotover-consolidate
8.1 Procedure for Instantaneous Shear Test
a bulk solid specimen at small normal loads.
8.1.1 Preshear:
8.1.1.1 Ascertain that the power supply has been turned on 8.1.1.5 Connect crossbeam 8 and lid 7 using the knurled
at least 15 min to ensure that the unit is properly warmed up. screws 9. Fasten screws only very slightly. Position the lid
D6773 − 22
FIG. 6 Counterbalance System
TABLE 1 Wall Friction Shear Cell Dimensions
8.1.1.6 Put tie rods 13 on both the bolts at the ends of
Standard Wall Friction crossbeam 8 (circular holes of tie rods 13) and seatings 16 at
Shear Cell,
load beams 17 (long hole of the tie rod 13).
Type WM
2 8.1.1.7 Ensure that the tie rods 13 have some clearance in
Cross-section (lid) A 226 cm
D
r 51 mm the seatings 16; that is, the tie rods must not be stressed at this
iD
r 99 mm
aD
stage. If it is not possible to connect the tie rods as described
r 42.5 mm
iSZ
above,donotmovethelidmanuallysincethiswouldinfluence
r 107.5 mm
aSZ
h 24 mm
the test result. Only use the motor drive to turn the shear cell
SZ
h 4mm
Mit
with the lid in a position where it is possible to connect the tie
Material Aluminum
rods to the load beams.
8.1.1.8 Append hanger 11 at hook 25 at the lower side of
crossbeam 8.
8.1.1.9 Carefully put an applied mass piece on the circular
concentrically on the shear cell and turned a few degrees
plate 19 of hanger 11 (mass needed for preshear or smaller
counterclockwise to its shear position (shear position: longitu-
mass).
dinal axis of the crossbeam is perpendicular to the front edge
of the casing 2). Direct the open side of hook 25 in the center 8.1.1.10 Remove hook 14, which is connected to the bal-
of crossbeam 8 to the right. Locate handle 24 of hanger 11 on ance arm, from its off-position mounting 32 and append it to
the right side of crossbeam 8 (Fig. 16). the central axis 10 (this already has been done in Fig. 16). To
D6773 − 22
FIG. 7 Main Dimensions of Shear Cell
do this, pull down the front end of the balance arm at the black 8.1.1.14 Holdthelidinitsliftedpositionwithonehandand
handle 46 provided for this (the handle is not shown in all append hanger 11 at hook 25 at the lower side of crossbeam 8.
figures; see Fig. 6).
8.1.1.15 Carefully place the lid concentrically on the shear
8.1.1.11 Follow 8.1.1.12 – 8.1.1.16 if the normal load at
cell on the bulk solid specimen. The lid must be in a position
preshear is less than 15 N. (These steps can also be used
turned a few degrees counterclockwise to its shear position
alternatively to 8.1.1.5 – 8.1.1.10.)
(shear position: longitudinal axis of the crossbeam is perpen-
8.1.1.12 Connect crossbeam 8 and lid 7 using the knurled
dicular to the front edge of the casing 2). Direct the open side
screws 9. Fasten screws only very slightly. Remove hook 14,
of hook 25 in the center of crossbeam 8 to the right. Locate
which is connected to the balance arm, from its off-position at
handle 24 of hanger 11 on the right side of crossbeam 8 (Fig.
mounting32andappendittothecentralaxis10.Thelidisthen
16).
in a “lifted position.”
8.1.1.16 Put tie rods 13 on both the bolts at the ends of
8.1.1.13 Put at least one applied mass piece on the circular
crossbeam 8 (circular holes of tie rods 13) and the seatings 16
plate 19 of the hanger 11.
at load beams 17 (long hole of the tie rod 13). Ensure that the
tie rods 13 have some clearance in the seatings 16; that is, the
NOTE 9—The mass on the hanger can be less than or equal to that
needed for preshear, but must not exceed 1 kg. tie rods must not be stressed at this stage. If it is not possible
D6773 − 22
FIG. 8 Determination of the Height of the Specimen
TABLE 2 Shear Cell Dimensions
NOTE 10—At the beginning of preshear, some powder may escape,
which is one reason why the lid may sink. Provided that 8.1.1.17 is
Standard Cell, Type
Small Cell, Type S
followed, loss of powder can be neglected.
M
3 A 3 A
Internal volume V ca. 900 cm ca. 200 cm
SZ
8.1.1.18 Check the adjustment of the rotational velocity
2 2
Cross-section (lid) A 226 cm 79 cm
D
(front panel 35). The circumferential velocity at the mean
r 51 mm 31 mm
iD
r 99 mm 59 mm diameter must be 1 to 2 mm/min.
aD
r 50 mm 30 mm
iSZ
8.1.1.19 Start the motor (front panel 35).
r 100 mm 60 mm
aSZ
h 40 mm 24 mm
SZ
NOTE 11—After some time both tie rods 13 are transferring tensile
h 4mm 4 mm
Mit
forces. The total force F (“shear force”) is then measured.
Material Aluminum or Aluminum or
Stainless Steel Stainless Steel
8.1.1.20 As soon as the shear force F stops increasing
A
Exact volume to be determined for each cell.
(steady-state flow is reached), Fig. 17, reverse the direction of
rotation of the shear cell. After both load beams are relieved
(shearforce F=0), continuerotatingtheshearcelluntilthetie
rods 13 have about 1 mm clearance in the seatings 16. Then
to connect the tie rods in this manner, use the motor drive to
stop the motor.
turn the shear cell with the lid to an appropriate position.
8.1.1.17 If not already done (at 8.1.1.9 or 8.1.1.13, 8.1.1.21 Record the force F measured at steady-state flow.
respectively), put additional applied mass pieces on the hanger (1)If the shear force does not reach a constant value,
11 for adjusting the normal force required for preshear. If the steady-state flow can be assumed if, after 30 mm of shear
lid sinks down more than around 10 mm, refill the shear cell displacement (measured at the mean radius of the shear cell
(remove the shear cell from the tester and go back to 7.3). annulus), this force does not increase more than 0.05% per
D6773 − 22
FIG. 9 Time Consolidation Bench
then begins to decrease (Fig. 17). This part of the test is called shear.
mm of shear displacement. If this condition has not been
NOTE 13—The value τ is the shear stress at failure (peak shear point)
achieved after 30 mm of displacement, continue preshear until
s
for the selected shear normal stress σ at the selected preshear normal
s
it is met. If the technician decides to terminate preshear before
stress σ . Metal-to-powder friction, which may occur at the side walls of
p
this condition is met, it must be noted before continuing with
the shear cell and at the tips of the bars under the lid, is assumed to be
the test.
negligiblebecausetheareaswheremetal-to-powderfrictionmayoccurare
(2)The shear force should not decrease during preshear. If
very small compared to the cross-section of the shear plane, and therefore
ignored.
it starts to do so after a period of constant value, stop preshear
immediately and begin the steps starting with 8.1.2.
8.1.2.2 Switch on the digital displacement indicator 31.
(3)Constancy of the values of the steady state shear stress
After the display of the indicator shows “0.00 mm,” set the
τ obtainedafterpreshearisanindicationofthereproducibility
p
indicator on the crossbeam 8. Position the probe tip through a
of consolidation. With correctly consolidated specimens indi-
hole in the crossbeam 8 in such a way that it presses on top of
vidualvaluesofthesteadystateshearstressshouldnotdeviate
the inner side wall of the shear cell 4 and the spacer tube 36 is
by more than 65% from the average steady state shear stress
in contact with the upper surface of the crossbeam 8 (Fig. 8).
for the given preshear normal stress. With some particulate
Note the displacement indicated on the display.
solids (particularly coarser particles), however, this tolerance
8.1.2.3 Repeat the measurement at the opposite side of the
cannot be achieved. If this happens it must be noted by the
crossbeam.
technician performing the test.
8.1.2.4 Remove the indicator 31.
8.1.2 Shear:
8.1.2.5 Calculate the mean value of both measured
8.1.2.1 Selectashearnormalstresslevelσ withintherange
s
displacements, which is the mean decrease in height ∆h of the
of 25 to 80% of the preshear normal stress level σ , and
p
bulk solid specimen. Note this mean value.
replace the mass m by a smaller mass m . Switch on the
Wp Ws
motor again in the forward direction.
8.1.2.6 Drive back the shear cell 4 until tie rods 13 are
relieved. Then switch off the motor.
NOTE12—Afterthetierods13aretensedagain,theshearforcerapidly
increases,goesthroughamaximumrepresentingtheyieldshearforce,and 8.1.2.7 Remove tie rods 13.
D6773 − 22
FIG. 10 Wall Friction Shear Cell (bottom ring)
wouldjumpagainandagainfrom8.1.2.1backto8.1.1.19untilalldesired
8.1.2.8 Unhook hook 14 from the central axis 10 thus
measuring points are determined. Only then would 8.1.2.2 and the
deactivating the counterbalance system.
following steps be performed.
8.1.2.9 Remove applied mass pieces from the hanger 11.
Procedure B is generally the preferred procedure, since it is less time
8.1.2.10 Unhook hanger 11 from the hook 25 at the lower
consuming than Procedure A. Unfortunately, some bulk solids are sensi-
side of the crossbeam 8.
tivetosheardeformationand,asaresult,theirshearstressvaluesdecrease
8.1.2.11 Take off the shear cell 4 along with the lid 7.
with large shear deformation. Sometimes a result of this can be that
8.1.2.12 Empty the shear cell; if necessary clean the shear Procedure B yields too small values of the unconfined yield strength (3).
TodetermineifProcedureBisappropriate,examineanewbulksolidfirst
cell, the lid and the driving axle.
with this procedure. Repeat the first measuring point at the end. If the
8.1.3 Additional Tests:
prorated shear stress is noticeably smaller than at the first measurement
8.1.3.1 Repeat 7, 8.1.1, and 8.1.2.
(say, a difference greater than 2.5%), use Procedure A for the product
8.1.3.2 Select 3 to 5 shear normal stress levels σ within the
s
under consideration, or at least limit the number of shear points measured
range of 25 to 80% of the preshear normal stress level σ , and
using Procedure B.
p
repeat 7, 8.1.1, and 8.1.2. If Procedure B is applicable, shear the specimen only until the shear
force becomes constant. Frequently, if the shear displacement is large at
8.1.3.3 Select higher preshear normal stress levels so that:
the first preshearing of a bulk solid specimen, the shear force passes over
σ =2σ
p,2 p,1
a product dependent, weak maximum (3). Afterwards, a constant shear
σ =4σ
p,3 p,1
force somewhat smaller than the maximum shear force is reached. Do not
σ =8σ
p,4 p,1
waituntilthislowerlevelisreached.Thepreshearingisfinishedwhenthe
NOTE 14—Some adjustment in preshear normal stress levels may be
maximum is reached; that is, the shear force no longer increases, and the
necessary in order to cover the range of major principal stresses σ
shear force does not yet start to decrease again. One can ascertain this
necessary to accurately calculate critical arching and/or ratholing dimen-
condition easily, if the shearing velocity is not too high.
sions.
In principle, all measurement results, as those of other shear testers,
havetobeconsideredcriticallyandappliedwiththenecessarycautionand
8.1.3.4 Repeat 7, 8.1.1, 8.1.2, and 8.1.3.2 for each selected
care.
preshear normal stress level.
8.2 Shear Testing Procedure for Time Consolidation
NOTE 15—Following the procedure given in 7, 8.1.1, and 8.1.2
(Procedure A) requires a new filling of the shear cell for each measure-
8.2.1 When a particulate solid is exposed to a normal or
ment; that is, each point on a yield locus. In the literature a second
compressive stress for some time it may gain strength. This
measuring procedure (Procedure B) is frequently recommended (for
gaininstrengthcanbemeasuredusingtheSchulzeRingShear
example, in (2)), where several points of a yield locus are determined
using the identical bulk solid specimen several times. In this case, one Tester, and the effect is called time consolidation.
D6773 − 22
FIG. 11 Dimensions of Wall Material Coupon
NOTE 17—For a selected preshear normal stress, specimen preparation
8.2.2 Timeconsolidationiscarriedoutusingaconsolidating
and preshear are the same as for the instantaneous test.
bench which consists of several shear cells which can be
independently loaded.The time that the specimens sit at rest is
8.2.4 Time Consolidation:
specified according to the application.
8.2.4.1 Perform each test for time consolidation in the
8.2.2.1 As an alternative to using a consolidation bench,
following way. Using the shear tester, prepare and preshear
consider the following: a critically consolidated specimen is
specimens with applied mass m in the normal manner and
Wp
preparedbypreshearingwithappliedmass m .Afterattaining
Wp
then reverse the rotation of the shear cell after preshear.
steady state flow, the rotation of the shear cell is stopped but
8.2.4.2 Remove the already relieved tie rods 13.
the direction is not reversed. The shear zone formed thus
8.2.4.3 Carefully unhook hook 14 of the counterbalance
remains under the normal and shear stresses corresponding to
system from the central axis 10 of the crossbeam 8. For this
steady state flow and is kept in this state for a defined time t.
stepaswellasthefollowingthrough8.2.4.11,becarefulnotto
If the shear cell rotation is then reversed, the shear force will
bump or jar the lid or cell; otherwise the results will be
drop to zero and the actual shear test may be performed in the
incorrect.
usual way.
8.2.4.4 Removetheappliedmasspiecesfromthehanger11.
NOTE 16—If the effect of time consolidation in the Schulze Ring Shear
8.2.4.5 Unhook hanger 11 from the hook 25 on the lower
Tester were measured as described above, one test would monopolize the
side of the crossbeam 8.
shear tester for a very long time. Creep of the specimen could also cause
a decrease in the applied shear force during the resting phase. 8.2.4.6 Completely unscrew the knurled screws 9, which
join the crossbeam 8 with the lid 7.
8.2.3 Specimen Preparation and Preshear Time Effect:
8.2.4.7 Carefully remove crossbeam 8 from lid 7.
8.2.3.1 After completion of instantaneous testing and
evaluation, perform time tests at the same preshear normal 8.2.4.8 Carefully put time consolidation crossbeam 26 cen-
stress levels. trally on the lid 7.
D6773 − 22
FIG. 12 Wall Friction Shear Cell Placed on the Ring Shear Tester
FIG. 13 Main Dimensions of Wall Friction Shear Cell
8.2.4.9 Fix plastic cap Z3 of time consolidation bench in its cell on a free supporting plate Z2 of the prepared time
upper position with the help of the fixing screw Z6 (Fig. 9, consolidation bench (Fig. 9, medium position).
right position). 8.2.4.11 Hold plastic cap Z3 with one hand, and loosen the
8.2.4.10 Remove the shear cell 4 along with the lid 7 from fixing screw Z6 with the other hand. Then let down the plastic
driving axle 5 carefully and without vibrations. Put the shear cap slowly, thereby leading loading rod Z4 with one hand so
D6773 − 22
FIG. 14 Scraping Off Excess Powder
FIG. 15 Ring Shear Tester with Shear Cell on Driving Axle 5
that it runs against the centric tip (or pit) of the time 8.2.4.13 TheMohrcircleshowninFig.18isdrawnthrough
consolidation crossbeam 26. Push plastic cap Z3 over plate Z2 point P (steady state flow) and is tangential to the yield locus.
(Fig. 9, left position). During time consolidation, the specimen is loaded with the
(1)The plastic cap must not hit against shear cell or lid. major principal stress σ of that Mohr circle as shown in Fig.
Any shocks can influence the bulk solid specimen and lead to 18.
incorrect measurement results.
NOTE 18—During preshear a normal stress as well as a shear stress is
8.2.4.12 Select the applied mass m in such a way that the
Wt
acting, although on the consolidating bench only normal stresses can be
stress state in the specimen during time consolidation is the
applied. Through nearly 40 years of industrial practice with the Jenike
same as during preshear (that is, steady state flow). Shear Tester (see Standard D6128), it has been found that the stress state
D6773 − 22
FIG. 16 Shear Cell 4 and Lid 7 Connected to Hanger 11, Counterbalance System and Tie Rods 12
developed by the application of normal stress alone can successfully magnitude of 10 to 50 Pa (depending on the bulk density of the bulk
approximate that developed in steady state flow.
solid).
When using a time consolidation bench, the masses of the lid 7 (mass
8.2.4.14 Calculate the force, which must act on the bulk
m ) and the time consolidation crossbeam 26 (mass m ) as well as the
L CB
solid at time consolidation, from:
massesoftheloadingrodZ4withthediskZ5(mass m )areactingonthe
C
bulk solid specimen. Thus, for an exact adjustment of the load one has to
F 5σ A (1)
t 1 D
determine the masses of lid 4, time consolidation crossbeam 26, and
NOTE 19—The mass of the bulk solid in the area of the bars of the lid
is neglected here, because it only produces a normal stress on the order of loadingrodZ4withdiskZ5.Toobtainmass m ofthemasseswhichhave
Wt
D6773 − 22
FIG. 17 Stress-Strain Curves—Preshear and Shear
FIG. 18 Yield Locus Showing Valid Shear Points
tobeplacedondiskZ5ofthetimeconsolidationbench,thesemasseshave
8.2.4.15 Since the shear strength after time consolidation is
to be subtracted from mass m = F/g, which would exert the force F as
t t t
not very sensitive to the force σ , it is sufficient to select m
1 Wt
determined following equation (2) :
to satisfy Eq 2 to within 65%.
m 5 F /g 2 m 2 m 2 m (2)
~ !
Wt t L CB C
NOTE 20—To reduce the danger of falling masses, put the applied mass
The remaining mass m is to be exerted through applied mass pieces
Wt
pieces one after the other on disk Z5, turning each applied mass piece by
on the bulk solid specimen; that is, corresponding applied masses have to
about 90° relative to the applied mass piece below.
be placed on disk Z5 of the time consolidation bench when the specimen
under consideration is loaded.
8.2.4.16 Store the specimen under load for the time interval
OftenonecanneglectthemassesofloadingrodZ4anddiskZ5,sothat
specified by the requesting agency or client.
one subtracts only the masses of lid 7 and time consolidation crossbeam
(1)The time consolidation bench may not be subjected to
26 from mass m = F/g:
t t
shocks or vibrations during this time. Also pay attention to
m 5 ~F /g! 2 m 2 m (3)
Wt t L CB
constant temperature. Do not expose the specimens in the time
When Eq 3 is used, the results of the time consolidation measurements
consolidation bench to direct sunlight.
gain some additional safety with regard to silo design for flow, since the
8.2.4.17 After the chosen time t has elapsed, remove the
massesoftheloadingrodZ4andthediskZ5willcauseasomewhatlarger
time consolidation. guide rollers 12 (see Figs. 2 and 3) from the ring shear tester.
D6773 − 22
8.2.4.18 Carefully remove the applied mass pieces from 8.3.10 Empty the bottom ring 48; if necessary clean the
disk Z5 of the time consolidation bench. For this step as well bottom ring 48, the lid 49, and the driving axle 5.
asthefollowingthrough8.2.4.23,becarefulnottobumporjar
8.3.11 Repeatwallfrictionteststwotothreetimeswithnew
the lid or cell; otherwise the results will be incorrect.
specimens of the particulate solid.
8.2.4.19 CarefullyliftuploadingrodZ4withplasticcapZ3
NOTE 23—Sometimes there will be a rapid oscillation of the indicated
and fix the loading rod Z4 in its upper position with fixing
shear force because of slip-stick behavior. Use the shear stress maxima
screw Z6 (Fig. 9, medium position).
recorded during shear to evaluate the wall friction angle ϕ'.
(1)The plastic cap must not hit against shear cell or lid. NOTE 24—In many cases, there is no distinct difference between static
and kinematic friction. However, the shear force may pass through a
Any shocks can influence the bulk solid specimen and lead to
maximum when starting a wall friction test; that is, there is a peak shear
incorrect measurement results.
stress at τ .
w6
8.2.4.20 Remove the shear cell 4 along with the lid 7 from
8.3.12 If static friction is suspected, the static angle of wall
the supporting plate Z2 carefully and without vibrations. Put
friction can be determined as follows: A test is performed as
the shear cell on driving axle 5 of the ring shear tester.
described above but when the shear force has passed through
8.2.4.21 Remove time consolidation crossbeam 26 from lid
the maximum, the direction of rotation is reversed. After the
7.
shear force has fallen to zero, the applied mass on the hanger
8.2.4.22 Carefully put crossbeam 8 on lid 7 and fix it into
is reduced and the motor is started again. The shear force will
position with knurled screws 9. Tighten knurled screws 9 only
again pass through a maximum and the procedure of reversing
loosely.
the direction of rotation and reducing the applied mass is
8.2.4.23 Append hanger 11 carefully at hook 25 which is
repeated. The peak values of τ are used to evaluate the static
w
located on the lower side of the crossbeam 8.
angle of wall friction.
8.2.5 Shear of Specimen After Time Consolidation:
8.4 Wall Friction Time Tests
8.2.5.1 Select a mass m . Perform shear in the same
Ws
8.4.1 Static wall friction tests with time consolidation are
mannerasforinstantaneousflow.Fortimetests,selectnomore
also known as adhesion tests.
than three shear normal stress levels for each preshear stress.
8.4.2 Cut three coupons of the same wall material and wash
NOTE 21—Due to the scatter obtained in time shear tests, it is
and dry them thoroughly.
recommended that they be performed at least twice at each shear normal
8.4.3 Perform a wall friction test using wall friction normal
stress. Only use the higher (highest) value.
stresses σ to σ , to obtain a defined compaction of the
w6 w1
8.3 Procedure for Wall Friction:
particulatesolidparticles.Increasetheloadtoσ andperform
w6
8.3.1 Start the motor.
a shear test until the shear stress attains a constant value.
Withoutstopping,reducetheloadtoσ .Whentheshearstress
w5
NOTE 22—After some time, both tie rods 13 are transferring tensile
againreachesaconstantvalue,
...