1、DEUTSCHE NORM February 1997 Determination of flexural strength of autoclaved aerated concrete English version of DIN EN 1351 ICs 91.1 00.30 Descriptors: Concrete, autoclaved aerated concrete, flexural strength, testing. Bestimmung der Biegezugfestigkeit von dampfgehrtetem Porenbeton European Standar
2、d EN 1351 : 1997 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been prepared by CEN/TC 177. The responsible German body involved in its preparation was the Normenausschu Bauwesen (Building and Civil Engi- neering Standards Committee), Te
3、chnical Committee Vorgefertigte Bauteile aus Porenbeton und haufwerksporigem Leichtbeton. This European Standard is part of a series of standards specifying methods used to check compliance of precast autoclaved aerated concrete elements with the requirements specified in the relevant product standa
4、rd. EN comprises 6 pages. 0 No part of this standard may be reproduced without the prior permission of DIN Deutsches Institut fr Normung e.V., Berlin. Beuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen) Ref. No. DIN EN 1351: 1997-02 English price group 06 Sal
5、es No. 1106 01.98 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1351 January 1997 ICs 91.100.30 Descriptors: Concrete, autoclaved aerated concrete, flexural strength, testing. English version Determination of flexural strength of autoclaved aerated concrete Dtermination de la rsistance la fle
6、xion du bton cellulaire autoclav dampfgehrtetem Porenbeton Bestimmung der Biegezugfestigkeit von This European Standard was approved by CEN on 1996-12-13. CEN members are bound to comply with the CENLENELEC Internal Regulations which stipulate the conditions for giving this European Standard the sta
7、tus 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. The European Standards exist in three official versions (English, French, German). A v
8、ersion 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, Finland, France, Germany,
9、Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1997. CE
10、N - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN 1351 : 1997 E Page 2 EN 1351 :1997 Contents Page Page Foreword 2 5.5 Examination of test specimens and determination of their dimensions and volume . 4 5.6 Conditioning of test specim
11、ens 4 1 Scope 2 2 Normative references 2 6 Procedure 4 . 3 Principle . 6.1 Flexural test . 4 6.2 Examination and measurement of test specimens 4 Apparatus 2 after the test 5 5.1 Sample . 3 8 Test report 5 5.3 Number of test specimens . 3 strength using the method of centre-point 5.4 Preparation of t
12、est specimens 3 loading . 6 7 Test results . 5 5 Test specimens 5.2 Shape and size of test specimens . 3 Annex A (normative) Determination of flexural . Foreword This European Standard has been prepared by Technical Committee CEN/TC 177 Prefabricated reinforced components of autoclaved aerated concr
13、ete or lightweight aggregate concrete with open structure, the Secretariat of which is held by DIN. 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. Thi
14、s European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting national standards withdrawn, by July 1997 at the latest. In accordance with the CENKENELEC Internal Regulations, the national standards organizations o
15、f 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 Kingdom. 1 Scope This European Standard specifies a met
16、hod of determining the flexural (tensile) strength of autoclaved aerated con- crete (AAC) by means of prismatic specimens taken from prefabricated components I). 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These nor-
17、mative 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 this European Standard only when incorporated in it by amendment or revision. For un- dated r
18、eferences, the latest edition of the publication re- ferred to applies. EN 678 Determination of the dry density of autoclaved aerated 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 specimen
19、 by means of two-point loading. The maximum load sustained is recorded and the flexural strength calculated. The method of centre-point loading may also be used and is specified in annex A. The procedure using two-point loading shall be the refer- ence test method. NOTE: In general, the method of ce
20、ntre-point load- ing as described in annex A yields higher values of the flexural strength than the method of two-point loading . 4 Apparatus The following apparatus shall be used: a) Saw suitable for cutting reinforced AAC compo- nents. b) Calipers, capable of reading the dimensions of the specimen
21、s to an accuracy of 0,l mm. c) Straightedge, with a length of approximately 300 mm, a 0,5 mm-feeler gauge, a 0,l mm-feeler gauge, and a square, for checking the flatness and the squareness of specimens. d) Balance, capable of determining the mass of the specimens to an accuracy of 0,l %. e) Testing
22、machine, capable of applying a vertical compressive load at the required uniform rate without shock or interruption. The limit of error of the machine and the load indication shall be such that the ultimate load can be determined to an accuracy of f2 %. The measuring range shall be such that the ult
23、imate load is higher than one-tenth of the range used. f) Loading device as shown in figure 1, for transmitting the load of the testing machine to the specimen. The loading device shall consist of two supporting roll- ers and two loading rollers. The rollers shall be manu- factured from steel and sh
24、all have a circular cross sec- tion with a diameter between 15 mm and 40 mm. They shall be at least 10mm longer than the width of the specimen. The axes of all rollers shall be parallel to each other. Each roller, except one of the supporting rollers, shall be capable of rotating around its longitud
25、inal axis I) A European Standard for prefabricated reinforced com- ponents of autoclaved aerated concrete is in prepara- tion. Page 3 EN1351:1997 _- and of being inclined in a plane normal to the longitudi- nal axis of the specimen. After correct centring in the testing machine, the axes of the hing
26、es of the three inclinable rollers shall be situated on a vertical plane which shall not deviate by more than fl mm from the axis of the compressive force of the testing machine. The middle axis between the loading rollers or the sup- porting rollers shall not deviate by more than fl mm from the axi
27、s of the testing machine (axis of the vertical compressive force). The centre distance between the supporting rollers (.e. the span), 1, shall be equal to 3h, where h is the nominal height of the specimen (normally, 50 mm). The loading rollers shall be equally spaced between the supporting rollers a
28、s shown in figure 1. All rollers shall be adjusted in their correct position, with all distances being set to an accuracy of f0,5 mm. g) Ventilated oven, capable of maintaining a tempera- ture of (105 f 5) “C (see NOTE). NOTE: In addition, a ventilated oven capable of maintaining a temperature of 40
29、 “C to 60 “C can be helpful for conditioning the specimens. 5 Test specimens 5.1 Sample The sample for specimen preparation shall be taken in so as to be representative of the product to be investigated. NOTE: The specimens may be prepared from pre- fabricated reinforced components. Alternatively, t
30、hey may be taken from prefabricated unreinforced components of the same mould. 5.2 Shape and size of test specimens The reference specimens shall be prisms cut from prefab- ricated components, with a height, h, of 50 mm, a width, b, of 50 mm and a length, L, of 200 mm. Specimens of other sizes may b
31、e used, provided that the flexural strength determined on such specimens can be directly related to the flexural strength determined on prisms measuring 50 mm x 50 mm x 200 mm. / 5.3 Number of test specimens A test set shall comprise three specimens. Whenever possible, one specimen shall be prepared
32、 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 specimens in the material relative to the rise of the mass shall be shown by the numbering, and the direction of rise
33、shall be marked on the specimens. 5.4 Preparation of test specimens The specimens shall be taken from the zone of the prefab- ricated component which is adjacent to the surface subject to maximum tension under service conditions (see figure 2). The longitudinal axis of the specimens shall be perpend
34、icu- lar to the direction of rise (see figure 2). They shall be cut from the component not before two days after removal from the autoclave. They shall not contain any reinforcement within the span, 1. The surfaces shall be plane and perpendicular to each other. The flatness of the surfaces shall be
35、 checked along the two diagonals of each surface and along the lines where the loading forces and the support reactions will be applied, using a straightedge and, if necessary, feeler gauges. De- viations by more than 0,5 mm along the diagonals and by more than 0,l mm along the lines where the loadi
36、ng forces and the support reactions will be applied shall be corrected by grinding. The angle between adjacent faces of the specimens shall also 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 b
37、y grind- ing. 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 intermediate layer between the rollers and the bearing surfaces, instead of grinding these area
38、s. The rubber or leather strips shall be of uniform thickness (approximately 5 mm), 25 mm in width, and extend over the full width of the specimen. 1 Loading rollers (capable of rotating and of being inclined independently of each other) 2 Supporting rollers (one fixed and the other capable of rotat
39、ing and of being inclined) Figure 1: Loading arrangement for two-point loading Page 4 EN 1351 :1997 Direction of rise - Zone 1 Zone 2 Zone 3 A A A / V v b b b 1 Component 2 Surface in tension under service conditions Figure 2: Sampling scheme 5.5 Examination of test specimens and determination of th
40、eir dimensions and volume The specimens shall be examined visually and any abnor- malities shall be reported. The dimensions of the specimens shall be measured to an accuracy of 0,l mm, using calipers. Measurements may be taken before or after conditioning according to 5.6. The width, b, and the hei
41、ght, h, shall be measured at both ends (b, and b, or h, and h,) and at midspan (b, or h,), 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 fac
42、es. The volume, V, of the individual specimens shall be calcu- lated by multiplying the arithmetic mean value of length measurements by the geometric mean value of width measurements (b, + 2b, + b,)/4 and the geometric mean value of height measurements (h, + 2h, + h,)/4. 5.6 Conditioning of test spe
43、cimens Specimens shall be conditioned at a temperature not ex- ceeding 60 “C until their moisture content is (6 f 2) % by mass (see NOTE). After reaching the specified moisture content, the speci- mens shall be conditioned, protected against moisture changes, for at least 24 h for ensuring moisture
44、equilibrium and thermal equilibrium with the laboratory atmosphere at (20 f 5) “C prior to the flexural test. Immediately before this test, the moist mass, mhm, of the specimens shall be deter- mined again, to an accuracy of 0,l %. The actual moisture content shall be determined after the test (see
45、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 specimens with the dry density determined in accordance with EN 678 on compan- ion specimens extracted from the same area of the same component. NOTE: The ex
46、pected moisture content of a speci- men, P, as a percentage by mass, may be calcu- lated from equation (1): where hum,i Qccomp = mhum/V is the moist density of the specimen, calculated by dividing its moist mass, mhum, by its volume V de- termined according to 5.5, in kg/m3; is the dry density of th
47、e companion specimen determined according to EN 678, in kg/m3. 6 Procedure 6.1 Flexural test All testing machine bearing surfaces shall be wiped clean and any loose material removed from the faces of the speci- men that will be in contact with the rollers. The loading device shall be correctly centr
48、ed in the testing machine (cf. clause 4 o). The specimen shall be placed on the support rollers of the loading device in the testing machine, correctly centred and aligned perpendicular to the rollers. The longitudinal axis shall not deviate by more than fl mm from the (theo- retical) plane of the h
49、inges of the inclinable rollers (see 4 o). If possible, the specimen shall be supported on that face corresponding to the face of the component subject to the maximum tensile stresses under service conditions (see figure 2). The load shall not be applied before all loading and sup- porting rollers are resting evenly against the specimen. Subsequently, the load may be applied rapidly, but without shock, until about 50 % of the anticipated breaking load have been reached. Then, the load shall be increased con- tinuously until rupture occurs, at a uniform rate which
