ASTM C1716/C1716M-23

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Designation: C1716/C1716M − 21 C1716/C1716M − 23
Standard Specification for
Compression Testing Machine Requirements for Concrete
Masonry Units, Related Units, and Prisms
This standard is issued under the fixed designation C1716/C1716M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This specification provides minimum design standards for testing machines used to measure the compressive strength of
concrete masonry units, related units, and masonry prisms covered under Test Methods C140/C140M and C1314.
1.2 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of this standard.
1.3 This specification shall be used to determine the maximum allowable specimen size and the maximum allowable load limits
on a specific specimen for any test machine. These limits are based on deflection of the bearing surfaces and the machine load
frame. These limits may not reflect the actual capacity of the machine and do not supersede the machine manufacturer’s
recommended operational limits. The user must determine if testing machine capacities, allowable specimen size and maximum
allowable load are appropriate for the sample to be tested.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
C140/C140M Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
C1093 Practice for Accreditation of Testing Agencies for Masonry
C1232 Terminology for Masonry
C1314 Test Method for Compressive Strength of Masonry Prisms
This specification is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.04 on
Research.
Current edition approved Dec. 1, 2021Dec. 1, 2023. Published December 2021December 2023. Originally approved in 2010. Last previous edition approved in 20202021
as C1716/C1716M – 20.C1716/C1716M – 21. DOI: 10.1520/C1716_C1716M-21.10.1520/C1716_C1716M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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C1716/C1716M − 23
E4 Practices for Force Calibration and Verification of Testing Machines
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this specification, refer to Terminology C1232.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bearing, adj—direct contact with the specimen being tested, as in bearing plate, bearing block, and bearing platen.
3.2.1.1 Discussion—
Plates, blocks or platens used for bearing purposes must have hardened bearing surfaces. Spacers do not have to be hardened.
Blocks are structural while plates are not.
3.2.2 block, n—steel piece 50 mm [2 in.] thick or greater that provides additional load capacity in bending to platens.
3.2.2.1 Discussion—
Blocks may be used to accommodate testing specimens of various heights in a testing machine. Hardened blocks can be used as
bearing surfaces.
3.2.3 composite, adj—made up of two or more pieces or materials.
3.2.4 load frame, n—all components of the testing machine that react against forces applied to the test specimen during testing.
3.2.5 plate, n—steel piece less than 50 mm [2 in.] thick that does not provide additional load capacity in bending to platens.
3.2.5.1 Discussion—
Plates may be used to accommodate test specimens of various heights in a testing machine but do not provide additional load
capacity in bending to platens or blocks. Hardened plates can be used as bearing surfaces.
3.2.6 platen, n—the primary loading surfaces of the testing machine.
3.2.6.1 Discussion—
Platen is a general term without specific properties implied. In general, the lower platen is semi-permanently fixed to the testing
machine and the upper platen is semi-permanently fixed to a hemispherical thrust bearing. Platens 50 mm [2 in.] thick or greater
act as blocks and bearing capacities in bending are calculated accordingly.
3.2.7 spacer, n—plates, blocks, or equipment and fixtures specific to a testing machine, used to adjust the position of bearing
surfaces to accommodate test specimens.
4. Testing Machine Requirements
4.1 Machine Loading Requirements:
4.1.1 The testing machine must be power operated and apply the load continuously, rather than intermittently, and without shock.
4.1.2 The machine must be capable of maintaining specific loading rates required by the test. Variations in the loading rate over
the elastic portion of the test shall not exceed 620 % of the set loading rate.
4.1.3 The testing machine must be capable of a minimum of 50 mm [2 in.] of continuous travel or displacement to accommodate
positioning and testing of a specimen.
4.2 Gauges and Displays—Gauges and displays indicating loads shall meet the requirements of Practices E4, except in no case
shall the verified force range include forces less than 100 times the resolution of the force indicator.
4.3 Accuracy—The accuracy and calibration of the testing machine shall meet the requirements of Practices E4. Prior to testing,
calibration is required:
4.3.1 At the frequency prescribed in Practice C1093,
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4.3.2 On original installation or after relocation,
4.3.3 Whenever there is reason to suspect the accuracy of the indicated loads, or
4.3.4 After making repairs or adjustments that affect the operation of the force applying system or the values displayed on the load
indicating system, except for zero adjustments that compensate for the mass of bearing blocks or specimen, or both.
4.4 Load Frame:
8 6
4.4.1 Load frames shall have a minimum longitudinal stiffness of 18 × 10 N/m [10 × 10 lb/in.].
NOTE 1—Evaluating the differential longitudinal strain in the side elements of the load frame due to an assumed eccentric loading can be used to estimate
compliance with 4.4.1. Limit the differential strain to 0.0001 mm/mm [0.0001 in./in.] at the maximum capacity of the machine or the rated capacity of
the specific test setup assuming the eccentricity of the load as 5 % of the maximum width of the specimen. See Appendix X1 for a discussion on allowable
longitudinal strain and machine capacity.
NOTE 2—Stiffer machines deflect less under load, have less frame distortion, truer load application and measurement capability.
NOTE 3—In testing machines with significant differences in lateral stiffness, the center of mass and center of effort shall lie on the axis perpendicular to
the axis of maximum lateral stiffness (see Fig. X1.1). Test specimen centroid of compressive strength may not coincide with its centroid of mass. Test
specimen section aspect ratio affects measured compressive strength but not mass.
4.4.2 If the design of the load frame makes it an integral part of the support against deflection for platens, blocks, or testing heads,
the specific parts of the load frame supporting platens, blocks, or testing heads shall meet the requirements of 4.9 for flatness, finish,
and materials.
4.4.3 Testing machines with fixed geometry frames and adjustable geometry frames are permitted.
4.5 Plates, Blocks, and Platens:
4.5.1 Plates, blocks, and platens shall meet requirements of 4.9 for flatness and surface finish. Surface treatments or plating to
reduce corrosion is permitted.
4.5.2 Plate—A one piece steel plate, less than 50 mm [2 in.] in thickness and greater than 11.5 mm [0.45 in.] in thickness. Plates
provide no additional load capacity in bending to platens or blocks.
4.5.3 Block—A one piece steel plate, 50 mm [2 in.] in thickness or greater.
4.5.4 Platen—A one piece steel plate, at least 25 mm [1 in.] thick when new and at least 22 mm [0.9 in.] thick when in service.
4.6 Spacers:
4.6.1 Spacers and bearing plates are permitted. Plates, blocks, and spacers are used to adjust the position of bearing surfaces to
accommodate test specimens.
4.6.2 Spacers excluding those provided by the testing machine manufacturer must be constructed of steel.
4.6.3 Non-ferrous and composite spacers, provided by the testing machine manufacturer, used between the upper testing head and
the lower platen shall have their load capacity clearly indicated on the spacer and shall be used with a block or bearing block
between the spacer and the test specimen.
NOTE 4—The block may be integral to the design of a composite spacer.
4.6.4 Spacers placed between the lower platen and lower bearing block must be a minimum of 6 mm [0.25 in.] wider and 6 mm
[0.25 in.] longer than the effective bearing area of the lower platen required for the test, or the length and width of the platen,
whichever is smaller.
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4.6.5 Spacers used between the upper and lower platen must meet all requirements of 4.9 for flatness and surface finish.
4.7 Hemispherical Head Design:
4.7.1 The upper platen or bearing surface of the testing machine shall be supported with a hemispherical thrust bearing to allow
small angular movement of the bearing surface.
NOTE 5—The preferred design includes a socket and ball hemispherical section semi-permanently or permanently attached to a single bearing block or
platen.
4.7.2 The ball and the socket shall be designed so that the steel in the contact area of the hemispherical bearing does not
permanently deform when loaded to the capacity of the testing machine or the rated load of the testing head.
4.7.3 The curved surfaces of the hemispherical bearing surface shall be kept clean and shall be lubricated with petroleum-type oil
such as conventional motor oil and not with grease.
NOTE 6—After contacting the specimen and application of small initial load, further tilting of the spherically seated block is neither intended nor desirable.
Spherical bearing blocks that rotate under load may reduce measured strengths.
4.7.4 The upper bearing surface and its attachment to the spherical seat shall be such that the bearing face can be rotated freely
at least 2° in any direction perpendicular to the axis of loading.
4.7.5 Close contact of the hemispherical bearing surfaces is preferred. Testing head designs with the surfaces not held in close
contact at all times shall have suitable alignment fixtures to assure the hemispherical bearing surfaces contact with lateral motion
less than 0.75 mm [0.03 in.].
4.7.6 Determine the allowable bearing and support areas for compliance with 4.10 using either 4.7.6.1 or 4.7.6.2.
4.7.6.1 When the radius of the hemispherical bearing does not extend beyond the bearing face of the upper platen or bearing block,
use either the mathematical solution in A1.2 or the graphical solution in A1.3.
4.7.6.2 When the radius of the hemispherical bearing extends beyond the bearing face of the upper platen or bearing block, use
only the graphical solution in A1.3.
4.7.7 Hemispherical bearings utilizing non-integral construction shall be designed to withstand lateral loads up to 7 % of the
maximum rated capacity of the testing head. Non-integral construction for hemispherical bearings are those bearing heads with the
convex hemispherical bearing section mechanically connected to the bearing block or upper platen, rather than those machined
from a single piece of steel.
4.7.8 If any portion of the upper platen is less than 50 mm [2 in.] thick, that portion shall be considered a spacer for calculations
of deflection under load. In a hemispherical head utilizing non-integral construction, the hemispherical bearing portion shall be
exempt from this requirement.
4.7.9 The bearing surface shall be designed to meet the requirements of 4.10 for deflection under load.
4.8 Lower Platen Design:
4.8.1 If the lower platen is the primary bearing surface, the bearing surface shall be designed to meet the requirements of 4.10 for
deflection under load.
4.8.2 If any portion of the lower platen is less than 50 mm [2 in.] thick, it shall be considered a spacer for calculations of deflection
under load.
4.9 Prescriptive Design Requirements for Blocks and Platens:
4.9.1 The working surfaces of blocks, plates and platens shall be finished to better than RMS (root mean square) 63. Bearing
C1716/C1716M − 23
surfaces shall be finished to RMS 30 or better. Top and bottom surfaces must be parallel within 60.0005 mm/mm [0.0005 in./in.]
on plates less than 50 mm [2 in.] thick and 60.0010 mm/mm [0.0010 in. ⁄in.] on platens and blocks 50 mm [2 in.] or greater in
thickness.
4.9.2 The length and width of bearing blocks, plates, and platens shall be a minimum of 6 mm [0.25 in.] larger than the length
and width of the test specimen, respectively.
4.9.3 Any surface within 1.2 mm [0.05 in.] of an edge is exempt from finish and flatness requirements.
4.9.4 Side surfaces not intended for loading are excluded from finish requirements.
4.9.5 Surfaces shall be flat within 60.0125 mm in 150 mm [0.0005 in. in 6 in.]. In addition, the entire surface excluding the edges
must be flat within 60.025 mm [0.001 in.]. If a bearing surface is rated to a maximum specimen size, the flatness tolerance applies
to the rated working area and the rated size must be clearly indicated on the front of the plate, block, or platen. The rated working
area shall meet the requirements of 4.9.2.
NOTE 7—Compliance with flatness tolerances can be determined using a suitable straight edge and feeler gauge. A 0.025-mm [0.001-in.] feeler gage
should be a no-go gage under a 150-mm [6-in.] straight edge on any portion of the working area. A 0.075-mm [0.003-in.] feeler gauge should be a no-go
gauge under a straight edge spanning any portion of the rated working area. The 0.075-mm [0.003-in.] feeler gauge is slightly oversized to allow for the
accuracy of straight edges over 300 mm [12 in.] in length. Other suitable methods may be used.
4.9.6 All surfaces used in bearing must be hardened to a minimum of 55 HRC (HB 560). Surface treatments such as plating shall
not be used to comply with the surface hardness requirements. Plates and blocks with one bearing surface shall have that surface
clearly indicated with permanent markings.
NOTE 8— It is preferred that bearing plates and bearing blocks have all working surfaces hardened. It is recommended that bearing surfaces be hardened
to a depth of 1.5 mm [0.06 in.] to allow for resurfacing of the bearing face.
4.9.7 Permanent markings designed to aid in positioning of specimen and spacers or to indicate rated size that are machined shall
not exceed 0.75 mm [0.03 in.] wide by 1.0 mm [0.04 in.] deep. Permanent markings that are etched shall not exceed 2.5 mm [0.1
in.] wide by 0.005 mm [0.0002 in.] deep.
NOTE 9—Markings are allowed, but not required by this standard. Studies have shown that machined markings can affect the results of high strength
specimens.
4.9.8 Surfaces with individual scratches larger than 0.25 mm [0.010 in.] wide by 50 mm [2 in.] long, and individual dents with
2 2
area exceeding 30 mm [0.05 in ] (approximately 6 mm [0.25 in] in diameter), and depth exceeding 0.12 mm [0.005 in.] shall not
be used as bearing surfaces. Scratches and dents outside the bearing area of 4.9.2 are excluded.
NOTE 10—Bearing surfaces with several scratches and or dents shall be replaced or resurfaced. Best engineering practice must be used to access the
number, location and significance of imperfections to the bearing surface.
4.9.8.1 Plates and blocks with dents and scratches exceeding those permitted by 4.9.8 may be used as spacers providing they meet
all other requirements of 4.9.5.
4.9.9 Holes and features required for fixtures or as part of the testing head design must have a minimum depth of cover to the
bearing surface of twice the diameter of the hole.
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4.10 Prescriptive Design for Deflection under Load:
4.10.1 The purpose of this section is to minimize the allowable deflections of platens and blocks under load. Deflection of the
bearing surfaces reduces the measured compressive strength of a test specimen. Use of spacers, plates and bloc
...