ASTM C120/C120M-09

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
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Designation:C120–06 Designation: C 120/C 120M – 09
Standard Test Methods of
Flexure Testing of Slate (Breaking Load, Modulus of
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Rupture, Modulus of Elasticity)
This standard is issued under the fixed designation C 120/C 120M; 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.
This standard has been approved for use by agencies of the Department of Defense.
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´ NOTE—To correct 10.1, the words “by centering the specimen” were added to the fourth sentence editorially in June 2006.
INTRODUCTION
Due to the unique properties of slate, the flexure test is better adapted to use for strength and
elasticity determinations than either compression or tension tests. Furthermore, several uses of slates
are such that these determinations are of special interest and value, besides furnishing comparative
data.
The property of slate termed “grain” causes a slab of the material to break transversely in one
direction somewhat more readily than at right angles to this direction. For this reason it is desirable
to test the strength and elasticity both parallel and perpendicular to the grain.
Breaking load test results for samples of roofing slate are only valid for the commercial supply of
slates of that thickness or greater. For the commercial supply of thinner roofings slates, testing on
samples of the minimum specified thickness must be conducted.
When comparing slates of equal thickness, but from various sources, slates which meet the required
breaking load at the lowest specimen thickness will yield the best performance on the roof in terms
of resistance to impact damage.
1. Scope
1.1 Thesetestmethodscoverdeterminationofthebreakingload,modulusofruptureandmodulusofelasticityofslatebymeans
of flexure tests.
1.2 Units—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.
1.3 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.
2. Referenced Documents
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2.1 ASTM Standards:
C99 Test Method for Modulus of Rupture of Dimension Stone
C119 Terminology Relating to Dimension Stone
3. Terminology
3.1 Definitions—All definitions are in accordance with Terminology C 119.
4. Significance and Use
4.1 These test methods are useful in indicating the differences in flexure (breaking load, modulus of rupture, modulus of
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These test methods are under the jurisdiction ofASTM Committee C18 on Dimension Stone and are the direct responsibility of Subcommittee C18.01 on Test Methods.
Current edition approved MarchApril 1, 2006.2009. Published March 2006.April 2009. Originally approved in 1925. Last previous edition approved in 20052006 as
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C120–05C 120–06 .
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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C 120/C 120M – 09
elasticity) between various slates. These test methods also provide one element in the comparison of slates.
5. Sampling
5.1 Select the sample to represent a true average of the type or grade of stone under consideration and of the quality supplied
to the market under the type designation to be tested.The sample may be selected by the purchaser or his authorized representative
fromthequarriedstoneortakenfromthenaturalledgeandshallbeofadequatesizetopermitthepreparationofthedesirednumber
of test specimens. When perceptible variations occur, the purchaser may select as many samples as are necessary for determining
the variations in flexure (breaking load, modulus of rupture, modulus of elasticity).
MODULUS OF RUPTURE
6. Test Specimens
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6.1 Structural or Electrical Slate— Six representative specimens, 12 by 1 ⁄2
...