ASTM C1144-89(2004)
(Test Method)Standard Test Method for Splitting Tensile Strength for Brittle Nuclear Waste Forms
Standard Test Method for Splitting Tensile Strength for Brittle Nuclear Waste Forms
SIGNIFICANCE AND USE
The splitting tensile-strength test can be used only on brittle waste materials such as ceramics, glass, concrete, or other materials that also have tensile fracture strengths that are less than one third of the compression strengths.
The test cannot be used for metal-matrix, bituminous, plastic, or coated-particle waste forms.
The strength values derived from this test cannot be applied to compressive-stress impact failure. The results apply only to tensile-stress failure. A separate compression-strength test, in which a cylindrical specimen is loaded on the flat surfaces, is required to determine compression strength along the lines of Test Methods C 39, D 2938, and C 773. Failures caused by impact must be determined in a separate test.
This test method is applicable only to brittle solids because these are the only materials that fail under a definable stress state for the test specimen geometry and loading. For instance, extensive local shearing at or near the loading points that will also occur for plastically deformable solids, such as ductile metals or viscous polymers, will change the stress distribution sufficiently to invalidate the elastic-stress calculation used to obtain the tensile stress across the vertical fracture plane. Ductile materials will not, in many cases, fracture in the test.
The effect of specimen size on the measured strength of brittle materials is not determined by this test method. In some materials, such as concretes, heterogeneities may be so large that tests on larger specimens are more representative. Testing along the lines of Test Method C 496 may then be appropriate to measure splitting tensile strength.
This test method does not determine the effects of time and environment on strength, nor does it address failure under long-duration static loading.
This test method can be used as a quality-control check and for optimizing waste form processing.
SCOPE
1.1 This test method is used to measure the static splitting tensile strength of cylindrical specimens of brittle nuclear waste forms. It provides splitting tensile-strength data that can be used to compare the strength of waste forms when tests are done on one size of specimen.
1.2 The test method is applicable to glass, ceramic, and concrete waste forms that are sufficiently homogeneous (Note 1) but not to coated-particle, metal-matrix, bituminous, or plastic waste forms, or concretes with large-scale heterogeneities. Cementitious waste forms with heterogeneities >1 to 2 mm and 5 mm can be tested using this procedure provided the specimen size is increased from the reference size of 12.7 mm diameter by 6 mm length, to 51 mm diameter by 100 mm length, as recommended in Test Method C 496 and Practice C 192.
Note 1—Generally, the specimen structural or microstructural heterogeneities must be less than about one-tenth the diameter of the specimen.
1.3 This test method can be used as a quality control check on brittle waste forms and may be useful for optimizing waste form processing. Meaningful comparison of waste forms, however, requires data obtained on specimens of one size.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:C1144–89(Reapproved2004)
Standard Test Method for
Splitting Tensile Strength for Brittle Nuclear Waste Forms
This standard is issued under the fixed designation C1144; 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 C39/C39M Test Method for Compressive Strength of Cy-
lindrical Concrete Specimens
1.1 This test method is used to measure the static splitting
C192/C192M Practice for Making and Curing Concrete
tensile strength of cylindrical specimens of brittle nuclear
Test Specimens in the Laboratory
waste forms. It provides splitting tensile-strength data that can
C496/C496M Test Method for Splitting Tensile Strength of
be used to compare the strength of waste forms when tests are
Cylindrical Concrete Specimens
done on one size of specimen.
C773 Test Method for Compressive (Crushing) Strength of
1.2 The test method is applicable to glass, ceramic, and
Fired Whiteware Materials
concrete waste forms that are sufficiently homogeneous (Note
D2938 Test Method for Unconfined Compressive Strength
1) but not to coated-particle, metal-matrix, bituminous, or
of Intact Rock Core Specimens
plastic waste forms, or concretes with large-scale heterogene-
E4 Practices for Force Verification of Testing Machines
ities. Cementitious waste forms with heterogeneities >1 to 2
2.2 Society of Manufacturing Engineers:
mmand<5mmcanbetestedusingthisprocedureprovidedthe
GeometricalToleranceInterpretations,SMEToolandManu-
specimen size is increased from the reference size of 12.7 mm
facturing Engineers Handbook
diameter by 6 mm length, to 51 mm diameter by 100 mm
length, as recommended in Test Method C496/C496M and
3. Summary of Test Method
Practice C192/C192M.
3.1 A right-circular cylinder of the waste solid is loaded
NOTE 1—Generally, the specimen structural or microstructural hetero-
diametrally between two hardened, parallel bearing blocks
geneities must be less than about one-tenth the diameter of the specimen.
positioned between the specimen and the two test machine
1.3 This test method can be used as a quality control check
platens, one of which is moving at a constant speed relative to
on brittle waste forms and may be useful for optimizing waste
the other (Fig. 1).
form processing. Meaningful comparison of waste forms,
3.2 As the load increases, the resultant stress eventually
however, requires data obtained on specimens of one size.
reaches the fracture strength of the material, and the specimen
1.4 The values stated in SI units are to be regarded as the
splitsalongtheverticaldiameter,usuallywithsomesubsidiary
standard.
fracture at other locations. The splitting tensile strength, T
1.5 This standard may involve hazardous materials, opera-
(MPa), is calculated from the measured fracture load as
tions, and equipment. This standard does not purport to
follows:
address all of the safety concerns, if any, associated with its
T 52P/pLD (1)
use. It is the responsibility of the user of this standard to
establish appropriate safety and health practices and deter- where:
P = appliedforce,orfractureload,atinitiationoffracture,
mine the applicability of regulatory limitations prior to use.
For specific hazard statements, see Section 7. N,
L = specimen length, mm, and
2. Referenced Documents
D = specimen diameter, mm.
3.3 The splitting tensile-strength test uses a compressive
2.1 ASTM Standards:
loading to effect a tensile stress. The stress state in the
specimen during the test is well documented by both theoreti-
calandexperimentalstressanalysis.Thestressstateisintended
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.07 on Waste
tobebiaxialwithauniformtensilestressnormaltotheloading
Materials.
axis across the anticipated fracture plane (the vertical diameter
Current edition approved Jan. 1, 2004. Published January 2004. Originally
approved in 1989. Last previous edition approved in 1997 as C1144-89(1997).
DOI: 10.1520/C1144-89R04.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Withdrawn. The last approved version of this historical standard is referenced
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM on www.astm.org.
Standardsvolume information, refer to the standard’s Document Summary page on Available from Society of Manufacturing Engineers, P.O. Box 930, One SME
the ASTM website. Dr., Dearborn, MI 48121.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C1144–89 (2004)
FIG. 1 Diametral Test Specimen and Apparatus
between loading points). The loading pads tend to prevent
compressive-stress failure near the loading points. In a valid
test, failure is initiated near the axis of the cylinder and
propagates on the plane defined by the lines of contact of the
bearingblockswiththespecimen(seeFig.2(a)andSection5).
4. Significance and Use
4.1 The splitting tensile-strength test can be used only on
brittle waste materials such as ceramics, glass, concrete, or
other materials that also have tensile fracture strengths that are
less than one third of the compression strengths.
4.2 The test cannot be used for metal-matrix, bituminous,
plastic, or coated-particle waste forms.
(a) Normal Tensile Failure (Valid Test)
4.3 The strength values derived from this test cannot be
(b) Triple-Cleft Failure (Valid Test)
applied to compressive-stress impact failure. The results apply
(c) Compression and Shear Failures (Invalid Test)
only to tensile-stress failure. A separate compression-strength
FIG. 2 Failure Modes
test, in which a cylindrical specimen is loaded on the flat
surfaces, is required to determine compression strength along
4.7 This test method can be used as a quality-control check
the lines of Test Methods C39/C39M, D2938, and C773.
and for optimizing waste form processing.
Failures caused by impact must be determined in a separate
test.
5. Interferences
4.4 This test method is applicable only to brittle solids
because these are the only materials that fail under a definable 5.1 Visually inspect the specimen after fracture. Disqualifi-
stress state for the test specimen geometry and loading. For cation is based on the occurrence of compression and shear
instance, extensive local shearing at or near the loading points failureorfailureatanobservablesurfaceflaw.See5.3,5.4,and
5.5 for guidance in identification of the failure mode. Report
that will also occur for plastically deformable solids, such as
ductile metals or viscous polymers, will change the stress identification of the failure mode in terms relatable to these
distribution sufficiently to invalidate the elastic-stress calcula- sections.
tion used to obtain the tensile stress across the vertical fracture 5.2 There are two fracture modes that indicate a valid test,
plane. Ductile materials will not, in many cases, fracture in the normaltensilefailureandtriple-cleftfailure,bothofwhichcan
test. be followed by additional severe fragmentation of the center
4.5 The effect of specimen size on the measured strength of vertical region of the specimen. A third type of failure, or
brittle materials is not determined by this test method. In some fracture, called compression and shear failure, invalidates the
materials, such as concretes, heterogeneities may be so large test results. Because of the possible varied fractures and
that tests on larger specimens are more representative. Testing because there is no satisfactory way to predict which will
along the lines of Test Method C496/C496M may then be occur, the specimen must be examined after the test to qualify
appropriate to measure splitting tensile strength. the results.
4.6 This test method does not determine the effects of time 5.3 Normal Tensile Failure—In normal tensile failure, the
and environment on strength, nor does it address failure under specimen splits along the loaded diameter (see Fig. 2(a)). This
long-duration static loading. is the ideal failure and can be used to compute splitting tensile
C1144–89 (2004)
strength. The fracture may not completely extend from one The thickness of the balsa wood shall be 1.6 6 0.2 mm (Note
bearing block to the other initially. The load to initiate the 3). Fully annealed OFHC copper foil 0.13 by 0.01-mm thick
fracture is used to calculate strength. (Note 3) is suitable for higher strength waste forms.
5.4 Triple-Cleft Failure—Triple-cleft failure is a variation
NOTE 3—Deviations in pad material sizes of this magnitude will not
on the normal tensile failure, and the specimen splits into four
affect test results.
approximately equal-sized pieces, two on each side of the
6.5 Load-Measurement System—Use a strip-chart or x-y
loaded diameter (see Fig. 2(b)). Tests exhibiting this failure
recorder to obtain a record of the loading force versus time.
also yield valid values of splitting tensile strength. Additional
Therecordermustbecapableofrespondingtosuddenchanges
fragmentation can occur when the fracture is initiated on the
in load (response time <1 s full scale). Use the strip-chart or
diametral plane, as in glasses where the stresses on the central
x-y recorder to record the calibration loads during a check of
unsupported vertical region (after initial splitting) cause frag-
the load-measurement system with dead weights or an electri-
mentation of that region.
cal method prior to testing. Use a load cell that has been
5.5 Compression and Shear Failure— In compression and
verified according to Practice E4. The chart speed shall be
shear failures, the specimen is crushed near the bearing blocks
appropriate for displaying the elastic or straight-line portion of
without fracturing through the diameter, or the specimen may
the loading at an angle no greater than 80° to the time axis. It
fail near the loading pads due to a local crushing or by
is imperative to have a continuous recording of load to ensure
fracturingatanyangleawayfromtheloadeddiameter(seeFig.
that the fracture is not missed.
2(c)). In some cases, the specimen may change shape before
6.6 Number of Tests—Initially, five valid test results should
fracture or may not fracture at all. Tests with these types of
be obtained. Calculate the percent relative standard deviation
failure or deformation cannot be used to compute splitting
of the five measured tensile strengths as follows:
tensilestrengths,andstressescalculatedfromsuchtestsarenot
s
reportable as tensile strengths. Choice of loading pad may
RSD ~%!5 ·100 (2)
¯
avoid these types of failure in some cases. T
where:
6. Apparatus
T = tensile strength for the ith test, and
i
6.1 Test Temperature—Conduct the test at room tempera- 1
T = the sample mean tensile strength= ⁄5 ( T , and
i=1 i
5 2
ture and report the test temperature. 1
¯
s = the sample standard deviation= ⁄5 ( ( T −T)
i=1 i
1/2
6.2 Testing Machine—Use a constant crosshead-speed ma-
.
−4
chine at a speed of 8 310 mm/s6 50% (Note 2). A fixed
6.6.1 If the percent relative standard deviation is less than
loading rate machine is not acceptable. The machine can be
20.1%, no additional tests are required. If the RSD (%)
either screw driven or otherwise controlled to give a fixed
exceeds 20.1%, use Table 1 to determine the number of
speed. The stiffness of the various members of the loading
additionaltestsrequired.IftheRSD(%)isgreaterthan27.1%,
system shall be sufficiently high, such that the total deflection
the material has variations in strength that are unusually large.
−8
per unit force is less than 10 m/N, not including the
Report the results of the ten tests in this case.
specimen.
6.6.2 The criterion for the sample sizes given in Table 1 is
based on the desire that the half-width of the 95% confidence
NOTE 2—Deviations in crosshead speeds of this magnitude will not
intervalfortheaveragetensilestrengthbenogreaterthan25%
affect test results.
of that value. If the tensile strength measurements come from
6.3 Bearing Blocks—Bearing blocks with Rockwell hard-
a normal distribution, this should be approximately true.
ness >60 HRC are required.Any permanent indentation of the
Naturally, the actual confidence-interval statements made will
bearing block invalidates the test. Suitable materials are tool
be based on the observed sample values, not the desired result.
steels hardened from 60 to 65 HRC by conventional heat
treatments and ground to obtain a smooth loading surface.The
7. Hazards
surfaces of the bearing blocks in contact with the pads shall be
7.1 Specimens of brittle materials under stress can fracture
flat to within 60.03 mm, parallel within 60.03 mm/mm (1.7°)
and produce flying fragments. In addition to other precautions,
measuredoneachoftwoperpendiculardirections,andperpen-
take precautions against injury by placing a shield around the
dicular to the loading axis within 60.03 mm/mm (1.7°).
specimen to stop such fragments.
6.4 Pad Materials—The choice of pad material depends on
the strength and elastic modulus of the material tested. A
suitable pad material is one that prevents contact between the
TABLE 1 Minimum Number of Required Tests (Based on the
test specimen and the bearing blocks but is soft enough to
Sample % Relative Standard Deviation from Five Tests)
distribute the load over a small area. If the specimen and
Sample Relative Standard Number of tests Number of
bearing block contact during the test (determined by visual
Deviation, RSD (%) required, (n) additional tests
inspection of the pad after testing), the test result is invalid. In
#20.1 5 0
general, balsa wood is a suitable pad material for testing glass
20.2 to 22.1 6 1
and other materials with splitting tensile strengths less than 22.2 to 23.9 7 2
24.0 to 25.5 8 3
approximately 100 MPa. The grain of the wood shall be
25.6 to 27.0 9 4
aligned perpendicular to the line of contact between specimen
$27.1 10 5
and bearing block with the grain parallel to the bearing block.
C1144–89 (2004)
TABLE 2 Required Calibration
8. Test Specimens
Instrument and
8.1 Use a specimen that is 12.7 6 0.3 mm in diameter and
Measurement Calibration Reference
Sensitivity
6.4 6 0.15 mm in length, round within a tolerance of 0.025
Specimen caliper micrometer, NIST traceable gage
mm,straightwithinatoleranceof0.050mm,andwiththeends
dimensions 0.01 mm or better blocks—every six months
square to the cylinder axis within a tolerance of 0.075 mm; the Specimen caliper micrometer, NIST traceable gage blocks
straigh
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