BS EN 1351-1997 Determination of flexural strength of autoclaved aerated concrete《蒸气加气混凝土的弯曲强度的测定》.pdf

1、 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1351 : 1997 The Eur

2、opean Standard EN 1351 : 1997 has the status of a British Standard ICS 91.100.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Determination of flexural strength of autoclaved aerated concreteBS EN 1351 : 1997 This British Standard, having been prepared under the direction o

3、f the Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 September 1997 BSI 1997 The following BSI references relate to the work on this standard: Committee reference B/523 Draft for comment 93/110405 DC ISBN 0 580 27

4、462 4 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee B/523, Prefabricated concrete and lightweight aggregate concrete with open structure, upon which the fo

5、llowing bodies were represented: Aggregate Concrete Block Association Autoclaved Aerated Concrete Association British Masonry Society British Precast Concrete Federation Ltd. Department of the Environment (Building Research Establishment) Institution of Structural Engineers Local Authority Organizat

6、ionsBS EN 1351 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 1351 3ii BSI 1997 BS EN 1351 : 1997 National foreword This British Standard has been prepared under the direction of Technical Committee B/523 and is the English langua

7、ge version of EN 1351 : 1997 Determination of flexural strength of autoclaved aerated concrete, published by the European Committee for Standardization (CEN). Cross-reference Publication referred to Corresponding British Standard EN 678 : 1993 BS EN 678 : 1994 Determination of the dry density of aut

8、oclaved aerated concrete Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 8, an inside back cover and a back cover.CEN European Co

9、mmittee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 All rights of reproduction and communication in any form and by any means reserved to CEN and its members. Ref. No. EN 1351 : 1997 E EUROPEAN

10、 STANDARD EN 1351 NORME EUROPE ENNE EUROPA ISCHE NORM January 1997 ICS 91.100.30 Descriptors: Concrete, cellular concrete, mechanical tests, bend tests, determination, tensile strength, procedure English version Determination of flexural strength of autoclaved aerated concrete De termination de la r

11、e sistance a la flexion du be ton cellulaire autoclave Bestimmung der Biegezugfestigkeit von dampfgeha rtetem Porenbeton This European Standard was approved by CEN on 1996-12-13. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

12、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 Central Secretariat or to any CEN member. This European Standard exists in three official versions (Eng

13、lish, 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 Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark,

14、Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1351 : 1997 BSI 1997 Foreword This European Standard has been prepared by Technical Committee CEN/TC 177, Prefabricated reinforced components

15、of autoclaved aerated concrete or lightweight aggregate concrete with open structure, the secretariat of which is held by DIN. 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 July 1997, and confli

16、cting national standards shall be withdrawn at the latest by July 1997. In order to meet the performance requirements as laid down in the product standard for prefabricated components of autoclaved aerated concrete, a number of standardized test methods are necessary. According to the CEN/CENELEC In

17、ternal Regulations the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United

18、 Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Principle 3 4 Apparatus 4 5 Test specimens 4 5.1 Sample 4 5.2 Shape and size of test specimens 4 5.3 Number of test specimens 4 5.4 Preparation of test specimens 4 5.5 Examination of test specimens and determination of their dim

19、ensions and volume 5 5.6 Conditioning of test specimens 5 6 Testing procedure 6 6.1 Flexural test 6 6.2 Examination and measurement of test specimens after the test 6 7 Test results 6 8 Test report 7 Annex A (normative) Determination of flexural strength using the method of centre-point loading 8Pag

20、e 3 EN 1351 : 1997 BSI 1997 0,5 h 0,5 h h hhh l = 3h L F/2 F/2 h 1 1 2 2 1. Loading rollers (capable of rotation and of being inclined independently of each other) 2. Supporting rollers ( one fixed and the other capable of rotation and of being inclined) Figure 1. Loading arrangement for two-point l

21、oading 1) A European Standard for prefabricated reinforced components of autoclaved aerated concrete, is in preparation at CEN. 1 Scope This European Standard specifies a method of determining the flexural (tensile) strength of autoclaved aerated concrete (AAC) 1) by means of prismatic test specimen

22、s taken from prefabricated components. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated refere

23、nces, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 678 Determination of dry density of autoclaved aerated

24、concrete 3 Principle The flexural strength is determined by applying a uniform bending moment in the middle third of the span of a simply supported prismatic test specimen by means of two-point loading. The maximum load sustained is recorded and the flexural strength is calculated. The method of cen

25、tre-point loading may also be used and is specified in annex A. The procedure using two-point loading shall be the reference test method. NOTE. In general, the method of centre-point loading as described in annex A gives higher values of the flexural strength than the method of two-point loading.Pag

26、e 4 EN 1351 : 1997 BSI 1997 4 Apparatus a) Any saw, suitable for cutting reinforced AAC components; b) Callipers, capable of reading the dimensions of test specimens to an accuracy of 0,1 mm; c) A straight-edge with a length of approximately 300 mm, a 0,5 mm feeler gauge, a 0,1 mm feeler gauge, and

27、a square, for checking the planeness and the squareness of test specimens; d) A balance, capable of determining the mass of test specimens to an accuracy of 0,1 % e) A testing machine, capable of applying a vertical compressive load at the required uniform rate without shock or interruption. The pre

28、cision of the machine and the load indication shall be such that the ultimate load can be determined with an accuracy of 2 %. The measuring range shall be such that the ultimate load is higher than one tenth of the range used. f) A loading device, according to figure 1, for transmitting the load of

29、the testing machine to the test specimen. The device for applying the loads shall consist of two supporting rollers and two loading rollers. The rollers shall be manufactured from steel and shall have a circular cross-section with a diameter between 15 mm and 40 mm; they shall be at least 10 mm long

30、er than the width of the test specimen. The axes of all rollers shall be parallel to each other. Each roller, except one of the supporting ones, shall be capable of rotating around its longitudinal axis and of being inclined in a plane normal to the longitudinal axis of the test specimen. After corr

31、ect centring in the testing machine, the axes of the hinges of the three inclinable rollers shall be situated on a vertical plane which shall not deviate by more than 1 mm from the axis of the compression force of the testing machine. The middle axis between the loading rollers or the supporting rol

32、lers, respectively, shall not deviate from the axis of the testing machine (axis of the vertical compression force) by more than 1 mm. The centre distance, l, between the supporting rollers (i.e. the span length) shall be equal to 3h where h is the nominal height of the test specimen (normally 50 mm

33、). The loading rollers shall be equally spaced between the supporting rollers as shown in figure 1. All rollers shall be adjusted in their correct position with all distances having an accuracy of 0,5 mm. g) A ventilated drying oven , capable of maintaining a temperature of (105 5) C (see note). In

34、addition, a ventilated drying oven capable of maintaining a temperature of (40 to 60) C can be helpful for conditioning of test specimens. 5 Test specimens 5.1 Sample The sample for the preparation of the test specimens shall be taken in such a manner that it is representative of the product to be i

35、nvestigated. NOTE. The test specimens may be prepared from prefabricated reinforced components. Alternatively, they may be taken from prefabricated unreinforced components of the same mould. 5.2 Shape and size of test specimens The reference test specimens shall be prisms cut from prefabricated comp

36、onents, with a height h =5 0m m ,a width b = 50 mm, and a length of L = 200 mm. Test specimens of other sizes may be used, provided that the flexural strength determined on such test specimens can be directly related to the flexural strength determined on prisms 50 mm 50 mm 200 mm. 33 5.3 Number of

37、test specimens A test set shall consist of three test specimens. Whenever possible, one test specimen shall be prepared from the upper third of the component, one from the middle and one from the lower third, in the direction of rise of the mass during manufacture (see figure 2). The position of the

38、 test specimens in the material relative to the rise of the mass shall be shown by the numbering, and the direction of rise shall be marked on the test specimens. 5.4 Preparation of test specimens The test specimens shall be taken from that zone of the prefabricated component which is adjacent to th

39、e surface with the maximum tensile stresses under service conditions (see figure 2). The longitudinal axis of the test specimens shall be perpendicular to the direction of rise (see figure 2). They shall be cut from the component, not before 2d after removal from the autoclave. They shall not contai

40、n any reinforcement within the span length l. The surfaces shall be plane and perpendicular to each other. The planeness of the surfaces shall be checked along both of their diagonals and along the lines where the loading forces and the support reactions will be applied, by means of a straight-edge

41、and, if necessary, by means of feeler gauges. Deviations by more than 0,5 mm along the diagonals and by more than 0,1 mm along the lines where the loading forces and the support reactions will be applied shall be corrected by grinding. The angle between adjacent faces of the test specimens shall als

42、o be checked, using a square and, if necessary, a 0,5 mm feeler gauge. Deviations from squareness by more than 0,5 mm per 50 mm ( 0,6) shall be corrected by grinding.Page 5 EN 1351 : 1997 BSI 1997 bbb W /3 W/3 w/3 W h 1 2 1. Component 2. Surface under tension under service conditions Zone 1 Zone 2 Z

43、one 3 Direction of rise Figure 2. Sampling scheme Alternatively, if the surfaces in contact with the loading rollers or support rollers depart from a plane by not more than 0,5 mm, rubber or leather strips may be used as a load distributing an intermediate layer between the rollers and the bearing s

44、urfaces, instead of grinding these areas. The rubber or leather strips shall be of uniform thickness (approximately 5 mm), 25 mm in width, and shall extend over the full width of the test specimen. 5.5 Examination of test specimens and determination of their dimensions and volume The test specimens

45、shall be examined visually, and any abnormalities shall be reported. The dimensions of the test specimens shall be measured to an accuracy of 0,1 mm, using callipers. Measurements may be taken before or after conditioning according to 5.6. The width b and the height h shall be measured at both ends

46、b 1 and b 3 or h 1 and h 3 , respectively) and at midspan (b 2 or h 2 , respectively), each value being the mean value of a total of two individual measurements, taken at two opposite longitudinal faces. The total length L shall be measured along the middle axes of two opposite longitudinal surface

47、s. The volume V of the individual test specimens shall be calculated by multiplying the arithmetic mean value of length measurements by the geometric mean value of width measurements (b 1 +2b 2 +b 3 )/4 and the geometric mean value of height measurements (h 1 +2h 2 +h 3 )/4. 5.6 Conditioning of test

48、 specimens The test specimens shall be dried till their mass related moisture content is (6 2) % (see note). In doing so the temperature shall not exceed 60 C. After reaching the specified moisture content, the test specimens shall be stored, protected against moisture changes, for at least 24 h at

49、room temperature for ensuring internal moisture equilibrium and thermal equilibrium with the laboratory at (20 5) C prior to the flexural test. Immediately before the flexural test the moist mass, m hum , of the test specimens shall be determined again, to an accuracy of 0,1 %. The actual moisture content shall be determined after the test (see last paragraph of 6.2). Prior to the test, attainment of the specified moisture content may be estimated by comparing the moist density of the test specimens with the dry densi