1、BRITISH STANDARDBS EN 12372:2006Natural stone test methods Determination of flexural strength under concentrated loadThe European Standard EN 12372:2006 has the status of a British StandardICS 73.020; 91.100.15g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g
2、50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 12372:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2007 BSI 2007ISBN 978-0-580-49920-3National forewordThis
3、British Standard was published by BSI. It is the UK implementation of EN 12372:2006. It supersedes BS EN 12372:1999 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee B/545, Natural stone.A list of organizations represented on B/545 can be obtained on re
4、quest to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date Comments
5、EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 12372December 2006ICS 73.020; 91.100.15 Supersedes EN 12372:1999 English VersionNatural stone test methods - Determination of flexural strengthunder concentrated loadMthodes dessai pour pierres naturelles - Dterminationde la rsistance la flexion sous
6、 charge centrePrfverfahren fr Naturstein - Bestimmung derBiegefestigkeit unter MittellinienlastThis European Standard was approved by CEN on 25 October 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the s
7、tatus of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A
8、version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Esto
9、nia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCH
10、ES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12372:2006: EEN 12372:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Principle4
11、 4 Symbols 4 5 Apparatus .4 6 Preparation of the specimens 5 6.1 Sampling.5 6.2 Test specimens5 6.2.1 Surface finish .5 6.2.2 Dimensions.5 6.2.3 Tolerance 5 6.2.4 Planes of anisotropy .5 6.2.5 Conditioning before testing6 7 Test procedure.6 8 Expression of the results6 9 Test report 6 Annex A (norma
12、tive) Statistical evaluation of the test results.12 A.1 Scope 12 A.2 Symbols and definitions .12 A.3 Statistical evaluation of test results 13 Bibliography 15 EN 12372:2006 (E) 3 Foreword This document (EN 12372:2006) has been prepared by Technical Committee CEN/TC 246 “Natural stones”, the secretar
13、iat 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 June 2007, and conflicting national standards shall be withdrawn at the latest by June 2007. This document supersedes E
14、N 12372:1999. The change of the specimens dimensions requested a revision of this European Standard. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Repub
15、lic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 12372:2006 (E) 4 1 Scope This European Standard speci
16、fies 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 referenced documents are indispensable for the application of this document.
17、For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12390 (all parts), Testing hardened concrete 3 Principle The principle of this method is to place a specimen on two rollers and to progre
18、ssively load the specimen in the middle. The breaking load is measured and the flexural strength calculated. 4 Symbols For the purposes of this document, the following symbols apply. Rtfflexural strength, in Megapascals F breaking load, in newtons a load rate, in Megapascals/second V loading rate, i
19、n newtons/second l distance between the supporting rollers, in millimetres b width of the specimen adjacent to the plane of fracture, in millimetres h thickness of the specimen adjacent to the plane of fracture, in millimetres L total length of the specimen, in millimetres 5 Apparatus 5.1 A balance
20、capable of weighing the specimen with an accuracy of 0,01 % of the mass of the specimen. 5.2 A ventilated oven capable of maintaining a temperature of (70 5) C. 5.3 A linear measuring device with an accuracy of 0,05 mm. 5.4 A testing machine of appropriate force, in accordance with the EN 12390 and
21、calibrated according to this European Standard. EN 12372:2006 (E) 5 5.5 A device for applying loads on the specimen by a centre-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 s
22、upporting rollers (see Figure 1). The distance between the two supporting rollers shall be reported as requested in 6.2.2. 5.6 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 excep
23、t where specially requested. At least 10 specimens shall be selected from a homogeneous batch (see also 6.2.4). 6.2 Test specimens 6.2.1 Surface finish As a standard reference, the surface finish of the faces of the specimens shall be sawn, honed or polished (identification test). In case of necessi
24、ty to test specimens with other surface finishes (e.g. flamed, sandblasted) as required for application, this may be done (technological test). For the technological test the specimens may be final products or sawn from final products. The surface intended for use shall be in contact with the two su
25、pporting rollers (facing downwards). In any case the kind of surface finish shall be stated in the report. 6.2.2 Dimensions For stones with a size of the largest grain lower than 25 mm, preferred dimensions are 50 mm 50 mm 300 mm. Other dimensions are possible, but shall fulfil the following require
26、ments: 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 in no case it shall be
27、 less than the thickness. The distance between the supporting rollers l shall be equal to five times the thickness. 6.2.3 Tolerance The tolerance on the distance between the supporting rollers l shall be 1 mm. 6.2.4 Planes of anisotropy If the stone shows planes of anisotropy (e.g. bedding, foliatio
28、n) 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 position of the planes of anisotropy
29、 is known, the test shall be carried out with the force applied on the face that will be loaded during use. EN 12372:2006 (E) 6 If the way of use of the stone is not known but the position of the planes of anisotropy is indicated on the specimens (by means of at least two parallel lines), the test s
30、hall 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. 6.2.5 Conditioning before testing The specimens shall be dried at (70 5) C to a constant mass. Constant mass is reached when the difference between two weighings carr
31、ied out (24 2) h apart is no greater than 0,1 % of the first of the two masses. After drying and prior to testing the specimens shall be stored at (20 5) C until the thermal equilibrium is reached. After that the test shall be performed within 24 h. 7 Test procedure Wipe the surface of the rollers c
32、lean and remove any loose grits from the faces of the specimen that will be in contact with the rollers. The specimen is placed centrally on the supporting rollers (see Figures 1 to 4). The loading roller is placed in the middle of the specimen. The load is increased uniformly at a rate of (0,25 0,0
33、5) MPa/suntil the specimen breaks. NOTE 1 The breaking load is rounded to the nearest 10 N and also the place where the fracture occurs. The width and the thickness of the specimen are measured adjacent to the fracture plane and the dimensions are expressed in millimetres to the nearest 0,1 mm. NOTE
34、 2 Where the loading rate (V) is needed in N/s the following equation can be used to determine the required rate in N/s: labhV322= (N/s) (1) 8 Expression of the results The flexural strength Rtfof each specimen is calculated using the following equation: Rtf=322Flbh(2)The result shall be expressed i
35、n Megapascals to the nearest 0,1 MPa. If the fracture is situated more than 15 % of the distance between the supporting rollers from the middle of the specimen and/or flaws are present (veins, fissures etc.) it shall be mentioned in the test report. 9 Test report The test report shall contain the fo
36、llowing information: a) unique identification number of the report; b) the number, title and date of issue of this European Standard, i.e. EN 12372; EN 12372:2006 (E) 7 c) the name and address of the test laboratory and the address where the test was carried out if different from the test laboratory
37、; d) the name and address of the client; e) it is the responsibility of the client to supply the following information: the petrographic name of the stone; the commercial name of the stone; the country and region of extraction; the name of the supplier; the direction of any existing plane of anisotr
38、opy (if relevant to the test) to be clearly indicated on the sample or on each specimen by means of two parallel lines; the name of the person or organization which carried out the sampling; the surface finish of the specimens (if relevant to the test); f) the date of delivery of the sample or of th
39、e specimens; g) the date when the specimens were prepared (if relevant) and the date of testing; h) the number of specimens in the sample; i) the dimensions of the specimens; j) the surface finish of the specimens; k) the rate of loading in Megapascals per second to the nearest 0,05 MPa/s;l) for eac
40、h specimen: the width and thickness adjacent to the fracture plane and the distance between the supporting rollers in millimetres to the nearest 0,1 mm, the orientation of the force relatively to any plane of anisotropy following Figures 2 to 4, the breaking force in newton to the nearest 10 N, the
41、flexural strength in Megapascals to the nearest 0,1 MPa, the location of the fracture and any anomalies observed; m) for each relevant direction of loading the mean value R tfof the flexural strength and the standard deviations, in Megapascals to the nearest 0,1 MPa; n) all deviations from the stand
42、ard and their justification; o) remarks. The test report shall contain the signature(s) and the role(s) of the responsible(s) for the testing and the date of issue of the report. It shall also state that the report shall not be partially reproduced without written consent of the test laboratory. EN
43、12372:2006 (E) 8 Key 1 loading roller 2 supporting roller Figure 1 Arrangement of loading of test specimen (centre point loading) EN 12372:2006 (E) 9 Key 1 loading roller 2 supporting roller Figure 2 Test arrangement for a specimen with the load applied perpendicular to the planes of anisotropy EN 1
44、2372:2006 (E) 10 Key 1 loading roller 2 supporting roller Figure 3 Test arrangement for a specimen with the load applied parallel to the planes of anisotropy EN 12372:2006 (E) 11 Key 1 loading roller 2 supporting roller Figure 4 Test arrangement for a specimen with the load applied perpendicular to
45、the edges of the planes of anisotropy EN 12372:2006 (E) 12 Annex A (normative) Statistical evaluation of the test results A.1 Scope This annex establishes a method for the statistical treatment of test results obtained following the natural stone test methods described in this European Standard. A.2
46、 Symbols and definitions Measured values x1, x2, xi, xnNumber of measured values n Mean value=iixnx1Standard deviation1)(=nxxsiCoefficient of variation v = xs(for individual values) Logarithmic meanxln=1nln xiiLogarithmic standard deviation1)(ln2lnln=nxxsiMaximum value Max Minimum value Min Lower ex
47、pected value )ln(lnx(Esske= where ks(quantile factor) is given in Table A.1 Quantile factor kssee Table A.1 EN 12372:2006 (E) 13 A.3 Statistical evaluation of test results For the calculation of the mean value x( ), the standard deviation (s) and the coefficient of variation (v) a normal distributio
48、n is assumed. For the calculation of the lower expected value (E) a logarithmic normal distribution is assumed. The lower expected value (E) corresponds to the 5 % quantile of a logarithmic normal distribution for a confidence level of 75 %. Table A.1 Quantile factor (ks) in dependence on the number
49、 of measured values (n) in correspondence to the 5 % quantile for a confidence level of 75 % n ks3 3,15 4 2,68 5 2,46 6 2,34 7 2,25 8 2,19 9 2,14 10 2,10 15 1,99 20 1,93 30 1,87 40 1,83 50 1,81 8 1,64 EN 12372:2006 (E) 14 The following examples should help to clarify the method: EXAMPLE 1 Calculation of mean value, standard deviation, maximum value and minimum value of 6 measured values: Measurement no Measured value x 1 2 000 2 2 150 3 2 200 4 2 300 5 2 350 6 2 400 - Mean value 2 333 Standa
