BS EN 1521-1997 Determination of flexural strength of lightweight aggregate concrete with open structure《开式结构轻集料混凝土挠曲强度的测定》.pdf

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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1521 : 1997 The Eur

2、opean Standard EN 1521 : 1996 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 lightweight aggregate concrete with open structureBS EN 1521 : 1997 This British Standard, having been prepare

3、d under the direction of the Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 August 1997 BSI 1997 The following BSI references relate to the work on this standard: Committee reference B/523 Draft for comment 94/105

4、893 DC ISBN 0 580 27963 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 structur

5、e, upon which the following bodies were represented: Aggregate Concrete Block Association Autoclaved Aerated Concrete Products Association British Masonry Society British Precast Concrete Federation Ltd. Department of the Environment (Building Research Establishment) Institution of Structural Engine

6、ers Local Authority OrganizationsBS EN 1521 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 1521 3ii BSI 1997 BS EN 1521 : 1997 National foreword This British Standard has been prepared by Technical Committee B/523 and is the Engli

7、sh language version of EN 1521 : 1996 Determination of flexural strength of lightweight aggregate concrete with open structure, published by the European Committee for Standardization. Cross-reference Publication referred to Corresponding British Standard EN 992 : 1995 BS EN 992 : 1996 Determination

8、 of the dry density of lightweight aggregate concrete with open structure 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, an EN title page, pages 2 to 6, an in

9、side back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. EN 1521 : 1996 E EUROPEAN STANDARD EN 1521 NORME E

10、UROPE ENNE EUROPA ISCHE NORM November 1996 ICS 91.100.30 Descriptors: Prefabricated elements, armatures, components, concrete, aggregates, mechanical tests, bend tests, determination, tensile strength English version Determination of flexural strength of lightweight aggregate concrete with open stru

11、cture De termination de la re sistance a la flexion du be ton de granulats le gers a structure ouverte Bestimmung der Biegezugfestigkeit von haufwerksporigem Leichtbeton This European Standard was approved by CEN on 1996-10-19. CEN members are bound to comply with the CEN/CENELEC Internal Regulation

12、s 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 Central Secretariat or to any CEN member. This Europea

13、n 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 Central Secretariat has the same status as the official versions. CEN members are the nationa

14、l standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1521 : 1996 BSI 1997 Foreword This European Standard has been prepared by Technical Committee

15、 CEN/TC 177, Prefabricated reinforced components of autoclaved aerated concrete or lightweight aggregate concrete with open structure, of which the secretariat 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 en

16、dorsement, at the latest by May 1997, and conflicting national standards shall be withdrawn at the latest by May 1997. In order to meet the performance requirements as laid down in the product standard for prefabricated components of lightweight aggregate concrete with open structure, a number of st

17、andardized test methods are necessary. According to the CEN/CENELEC Internal 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, N

18、etherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Principle 3 4 Apparatus 3 5 Test specimens 3 5.1 Sample 3 5.2 Shape and size of test specimens 3 5.3 Number of test specimens 4 5.4 Preparation of test speci

19、mens 4 5.5 Examination of test specimens and determination of their dimensions and volume 4 5.6 Conditioning of test specimens 5 6 Testing procedure 5 6.1 Flexural test 5 6.2 Examination and measurement of test specimens after the test 5 7 Test results 6 8 Test report 6Page 3 EN 1521 : 1996 BSI 1997

20、 1 Scope This European Standard specifies a method of determining the flexural (tensile) strength of lightweight aggregate concrete with open structure (LAC) according to prEN 1520 by means of prismatic test specimens taken from prefabricated components. 2 Normative references This European Standard

21、 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 references, subsequent amendments to or revisions of any of these publications apply to th

22、is European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 992 Determination of dry density of lightweight aggregate concrete with open structure prEN 1520 Prefabricated components of lightweight ag

23、gregate concrete with open structure 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

24、calculated. 4 Apparatus a) any saw, suitable for wet cutting reinforced LAC components; b) calipers, capable of reading the dimensions of test specimens to an accuracy of 0,1 mm; c) a straight-edge, with a length of approximately 450 mm, feeler gauges (0,2 mm, 0,5 mm, 1,0 mm, and 3 mm) and a square,

25、 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 precision o

26、f 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 the test

27、ing 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 longer than

28、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 correct cent

29、ring 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 rollers, re

30、spectively, 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 100 mm). The

31、 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 1 mm. g) a room or cabinet, capable of maintaining a temperature of (20 5) C, for storage of the test specime

32、ns; h) a ventilated drying oven, capable of maintaining temperatures of (45 5) C and (105 5) C. i) a water storage tank, for conditioning of test specimens. Provision of automatic control of water temperature to (20 5) C shall be made where the tank is located in a room not having temperature contro

33、lled within that range. 5 Test specimens 5.1 Sample The sample for the preparation of the test specimens (usually a prefabricated reinforced component) shall be taken in such a manner that it is representative of the product to be investigated. 5.2 Shape and size of test specimens The reference test

34、 specimens shall be prisms cut from prefabricated components, with a height h = 100 mm, a width b = 100 mm, and a length of L = 400 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 de

35、termined on prisms 100 mm3 100 mm3 400 mm.Page 4 EN 1521 : 1996 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)

36、Figure 1. Loading arrangement 5.3 Number of test specimens A test set shall consist of three test specimens. 5.4 Preparation of test specimens The test specimens shall be taken from the central area near the longitudinal axis of the component in such a way that their longitudinal axis is parallel to

37、 the longitudinal axis of the component and that one of the longitudinal surfaces coincides with that surface of the component, where the maximum flexural stresses are expected to occur under service conditions. The test specimens shall be cut from the component at an age of 2 d if possible. They sh

38、all contain no reinforcing bars. The surfaces of the test specimens 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 strai

39、ght-edge and, if necessary, by means of feeler gauges. Deviations by more than 3,0 mm along the diagonals and by more than 0,2 mm along the lines where the loading forces and the support reactions will be applied shall be corrected by grinding or cutting. The angle between adjacent longitudinal face

40、s of the test specimens shall also be checked, using a square and, if necessary, a 1 mm feeler gauge. Deviations from squareness by more than 1 mm per 100 mm ( 0,6) shall be corrected by grinding or cutting. Alternatively, if the surfaces in contact with the loading rollers or support rollers depart

41、 from a plane by not more than 0,5 mm, rubber or leather strips may be used as a load distributing intermediate layer between the rollers and the bearing surfaces, instead of grinding these areas. The rubber or leather strips shall be of uniform thickness (approximately 5 mm), 25 mm in width, and sh

42、all 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 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

43、 mm, using calipers. Measurements may be taken before or after conditioning according to 5.6.Page 5 EN 1521 : 1996 BSI 1997 The width b and the height h shall be measured at both ends (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 va

44、lue 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 surfaces. The volume V of the individual test specimens shall be calculated by multiplying the arithmetic mean value of len

45、gth 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 specimens After cutting, the test specimens shall be allowed to dry for (1 0,5) h in air with the temperature of (2

46、0 5) C. Immediately afterwards they shall be sealed in vapour proof sealing and cured for 14 d at the above temperature. After this curing period the sealing shall be removed, and the test specimens shall be stored in a ventilated drying oven at a temperature of (45 5) C until constant mass is attai

47、ned. The mass of the test specimens is considered constant if after 24 h of further drying it has not changed by more than 0,2 %. Directly after removal from the drying oven, the test specimens shall be immersed in water of drinking water quality at (20 5) C for a period of 7 d. Then the test specim

48、ens shall be allowed to drip dry for (1 0,5) h before determination of the flexural strength. Immediately before testing, the moist mass m hum of the test specimens shall be determined to an accuracy of 0,1 %. NOTE. The purpose of the drying and wetting procedure specified in this clause is simulati

49、on of unfavourable conditions with respect to flexural strength due to possible shrinkage cracking and strength reduction due to water saturation. 6 Testing procedure 6.1 Flexural test All testing machine bearing surfaces shall be wiped clean and any loose material shall be removed from the surfaces of the test specimen that will be in contact with the rollers. The loading device shall be correctly centred in the compression testing machine (see 4f). The test specimen shall be placed on the support roll