EN 12372:2022
(Main)Natural stone test methods - Determination of flexural strength under concentrated load
Natural stone test methods - Determination of flexural strength under concentrated load
This document specifies a test method for determination of flexural strength under a concentrated load for natural stone. Both an identification and a technological product testing procedure are included.
Prüfverfahren für Naturstein - Bestimmung der Biegefestigkeit unter Mittellinienlast
Dieses Dokument legt ein Prüfverfahren für die Beurteilung von Naturstein durch die Bestimmung der Biegefestigkeit unter Mittellinienlast fest. Es sind sowohl eine Identitätsprüfung als auch eine Produktprüfung enthalten.
Méthodes d'essai pour pierres naturelles - Détermination de la résistance à la flexion sous charge centrée
Le présent document spécifie une méthode d'essai permettant de déterminer la résistance à la flexion sous charge centrée des pierres naturelles. Il comprend un mode opératoire d'essai d'identification ainsi qu'un mode opératoire d'essai technologique du produit.
Preskušanje naravnega kamna - Ugotavljanje upogibne trdnosti s koncentrirano obremenitvijo na sredini razpona
Ta dokument določa preskusno metodo za ugotavljanje upogibne trdnosti naravnega kamna s koncentrirano obremenitvijo na sredini razpona. Vključena sta postopek prepoznavanja in postopek tehnološkega preskušanja proizvoda.
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2022
Nadomešča:
SIST EN 12372:2007
Preskušanje naravnega kamna - Ugotavljanje upogibne trdnosti s koncentrirano
obremenitvijo na sredini razpona
Natural stone test methods - Determination of flexural strength under concentrated load
Prüfverfahren für Naturstein - Bestimmung der Biegefestigkeit unter Mittellinienlast
Méthodes d'essai pour pierres naturelles - Détermination de la résistance à la flexion
sous charge centrée
Ta slovenski standard je istoveten z: EN 12372:2022
ICS:
73.020 Rudarstvo in kamnolomsko Mining and quarrying
izkopavanje
91.100.15 Mineralni materiali in izdelki Mineral materials and
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 12372
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2022
EUROPÄISCHE NORM
ICS 91.100.15 Supersedes EN 12372:2006
English Version
Natural stone test methods - Determination of flexural
strength under concentrated load
Méthodes d'essai pour pierres naturelles - Prüfverfahren für Naturstein - Bestimmung der
Détermination de la résistance à la flexion sous charge Biegefestigkeit unter Mittellinienlast
centrée
This European Standard was approved by CEN on 10 January 2022.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12372:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms, definitions and symbols . 4
3.1 Terms and definitions . 4
3.2 Symbols . 4
4 Principle . 4
5 Apparatus . 4
5.1 Balance . 4
5.2 Ventilated oven . 5
5.3 Linear measuring device . 5
5.4 Testing machine . 5
5.5 Device for applying loads on the specimen by a three-point load . 5
5.6 Room . 5
6 Preparation of the specimens . 5
6.1 Sampling . 5
6.2 Test specimens . 5
6.2.1 Surface finish . 5
6.2.2 Technological test . 5
6.2.3 Dimensions. 5
6.2.4 Tolerance . 6
6.2.5 Planes of anisotropy . 6
6.2.6 Conditioning before testing. 6
7 Test procedure . 6
8 Expression of the results . 7
9 Test report . 7
Annex A (normative) Statistical evaluation of the test results . 13
A.1 General. 13
A.2 Symbols . 13
A.3 Statistical evaluation of test results . 13
Annex B (informative) Calculation of flexural strength for off-centre specimen fracture . 16
Bibliography . 18
European foreword
This document (EN 12372:2022) has been prepared by Technical Committee CEN/TC 246 “Natural
stones”, the secretariat of which is held by UNI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2022, and conflicting national standards shall
be withdrawn at the latest by September 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12372:2006.
In comparison with the previous edition, the following technical modifications have been made:
— inclusion of an informative annex (Annex B) presenting an alternative method for calculation of
flexural strength for off-centre specimen fracture.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
1 Scope
This document specifies a test method for determination of flexural strength under a concentrated load
for natural stone. Both an identification and a technological product testing procedure are included.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12390-4, Testing hardened concrete - Part 4: Compressive strength - Specification for testing machines
3 Terms, definitions and symbols
3.1 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/
3.2 Symbols
For the purposes of this document, the following symbols apply.
Symbol Quantity Unit
F breaking load N
L total length of the specimen mm
R flexural strength MPa
tf
V loading rate N/s
a load rate MPa/s
b width of the specimen adjacent to the plane of fracture mm
h thickness of the specimen adjacent to the plane of fracture mm
l distance between the supporting rollers mm
4 Principle
The principle of this method is to place a specimen on two rollers and to progressively load the specimen
in the middle. The breaking load is measured and the flexural strength calculated.
5 Apparatus
5.1 Balance
A balance capable of weighing the specimen with an accuracy of 0,01 % of the mass of the specimen.
5.2 Ventilated oven
A ventilated oven capable of maintaining a temperature of (70 ± 5) °C.
5.3 Linear measuring device
A linear measuring device with an accuracy of 0,05 mm.
5.4 Testing machine
A testing machine of appropriate force, in accordance with EN 12390-4 and calibrated according to this
document.
5.5 Device for applying loads on the specimen by a three-point load
A device for applying loads on the specimen by a three-point load. It consists of two lower rollers
(supporting rollers) and one upper roller (load-applying roller) which shall be centred exactly in the
middle between the two supporting rollers (see Figure 1). The distance between the two supporting
rollers shall be reported as requested in 6.2.3 and 6.2.4.
5.6 Room
A room which can be maintained at a temperature of (20 ± 10) °C.
6 Preparation of the specimens
6.1 Sampling
The sampling is not the responsibility of the test laboratory except where specially requested. At least 10
specimens shall be selected from a homogeneous batch (see also 6.2.5).
6.2 Test specimens
6.2.1 Surface finish
The surface finish of the faces of specimens used as a standard reference shall be sawn, honed or polished
(identification test).
6.2.2 Technological test
For the technological test, specimens may be finished products or specimens sawn from slabs or other
semi-finished or finished products.
If the surface of a specimen has an applied texture (e.g., flamed, bush hammered, shot blasted), the nature
of the applied texture shall be stated in the report.
If a mesh or similar reinforcement has been attached to a specimen, this shall be removed prior to testing
or its presence shall be stated in the test report.
The dimensions of the specimens shall be reported.
6.2.3 Dimensions
For stones with a size of the largest grain lower than 25 mm, preferred dimensions are
50 mm × 50 mm × 300 mm with a tolerance of ± 3 mm for each dimension.
Other dimensions are possible, but shall fulfil the following requirements:
— the thickness h shall be between 25 mm and 100 mm and shall be greater than twice the size of the
largest grain in the stone;
— the total length L shall be equal to six times the thickness;
— the width b shall be between 50 mm and three times the thickness (50 mm ≤ b ≤ 3h), and it shall not
be less than the thickness;
— a tolerance of ± 3 mm for each dimension.
The distance between the supporting rollers l shall be equal to five times the thickness.
6.2.4 Tolerance
The tolerance on the distance between the supporting rollers l shall be ±1 mm.
6.2.5 Planes of anisotropy
If the stone shows planes of anisotropy (e.g. bedding, foliation) the specimens shall be prepared in
accordance with at least one of the arrangements shown in Figures 2 to 4 and the direction of the planes
of anisotropy shall be marked on each specimen by at least two parallel lines.
If the use of the stone in respect of the direction of the planes of anisotropy is known, the test shall be
carried out with the force applied on the face that will be loaded during use.
If the way of use of the stone is not known but the direction of the planes of anisotropy is indicated on the
specimens (by means of at least two parallel lines), the test shall be carried out on each of the three
arrangements shown in Figures 2 to 4; the total number of specimens will then be 3 times 10.
...
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