1、BS ISO1920-8:2009ICS 91.100.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDTesting of concretePart 8: Determination of dryingshrinkage of concrete for samplesprepared in the field or in thelaboratoryThis British Standardwas published underthe authority of the
2、Standards Policy andStrategy Committee on 30November 2009 BSI 2009ISBN 978 0 580 59476 2Amendments/corrigenda issued since publicationDate CommentsBS ISO 1920-8:2009National forewordThis British Standard is the UK implementation of ISO 1920-8:2009.The UK participation in its preparation was entruste
3、d to TechnicalCommittee B/517/1, Concrete production and testing.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.
4、Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 1920-8:2009Reference numberISO 1920-8:2009(E)ISO 2009INTERNATIONAL STANDARD ISO1920-8First edition2009-04-01Testing of concrete Part 8: Determination of drying shrinkage of concrete for samples prepared in the fie
5、ld or in the laboratory Essais du bton Partie 8: Dtermination du retrait de schage du bton dchantillons prpars sur le terrain ou en laboratoire BS ISO 1920-8:2009ISO 1920-8:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may
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8、file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2009 All rights reserved. Unless otherwise specified, no part of this publication may be rep
9、roduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22
10、 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 1920-8:2009ISO 1920-8:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principl
11、e. 2 5 Apparatus 2 6 Test samples and specimens 7 6.1 Sampling 7 6.2 Test specimens . 8 7 Procedure 8 7.1 Measurement of consistence and temperature of concrete. 8 7.2 Preparation and filling of the moulds . 8 7.3 Compacting of concrete. 8 7.4 Curing of specimens 9 7.5 Drying and measurement of spec
12、imens. 10 8 Calculation and expression of results 12 9 Test report . 12 10 Precision for laboratory-prepared specimens. 14 Annex A (informative) A suitable horizontal length comparator. 15 BS ISO 1920-8:2009ISO 1920-8:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organizatio
13、n for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has
14、 the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Inter
15、national Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publicat
16、ion as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent righ
17、ts. ISO 1920-8 was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-stressed concrete, Subcommittee SC 1, Test methods for concrete. ISO 1920 consists of the following parts, under the general title Testing of concrete: Part 1: Sampling of fresh concrete Part 2: Prope
18、rties of fresh concrete Part 3: Making and curing test specimens Part 4: Strength of hardened concrete Part 5: Properties of hardened concrete other than strength Part 6: Sampling, preparing and testing of concrete cores Part 7: Non-destructive tests on hardened concrete Part 8: Determination of dry
19、ing shrinkage of concrete for samples prepared in the field or in the laboratory Part 9: Determination of creep of concrete cylinders in compression The following part is under preparation: Part 10: Determination of static modulus of elasticity in compression BS ISO 1920-8:2009INTERNATIONAL STANDARD
20、 ISO 1920-8:2009(E) ISO 2009 All rights reserved 1Testing of concrete Part 8: Determination of drying shrinkage of concrete for samples prepared in the field or in the laboratory 1 Scope This part of ISO 1920 specifies a method for determining the length changes of concrete specimens due to drying i
21、n air, and the method of preparing and curing the concrete specimens to be tested. It is applicable for the testing of specimens prepared in the laboratory or in the field, in which the maximum nominal size of aggregate in the concrete, in accordance with ISO 6274, does not exceed 25 mm. The precisi
22、on statement in Clause 10 does not apply to specimens that have had non-standard initial curing (normally field-prepared specimens). In addition, this part of ISO 1920 requires that field-prepared specimens be marked, recorded and reported as such. NOTE 1 This test method is not always suitable for
23、very low slump concrete (less than 20 mm), primarily due to the difficulties in obtaining adequate compaction. Provided adequate compaction is obtained, the method is applicable. NOTE 2 The method is specifically developed for measurement of drying shrinkage of concrete, but it is capable of adaptat
24、ion for measurement of length changes of specimens subjected to a variety of environmental conditions. 2 Normative references The following referenced documents are essential for the application of this part of ISO 1920. For dated references, only the edition cited applies. For undated references, t
25、he latest edition of the referenced document (including any amendments) applies. ISO 1920-1, Testing of concrete Part 1: Sampling of fresh concrete ISO 1920-2, Testing of concrete Part 2: Properties of fresh concrete ISO 1920-3:2004, Testing of concrete Part 3: Making and curing test specimens ISO 6
26、274, Concrete Sieve analysis of aggregates 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 preparing laboratory laboratory responsible for sampling of concrete, moulding of specimens, initial curing in moulds, demoulding, initial moist curing
27、 and transport to measuring laboratory (if required) BS ISO 1920-8:2009ISO 1920-8:2009(E) 2 ISO 2009 All rights reserved3.2 measuring laboratory laboratory responsible for completion of initial moist curing, storage in drying room and measurement of specimens NOTE In some instances, the preparing an
28、d measuring laboratories will be the same. 4 Principle Specimens are cured and air dried for a specified time, and the change in length is measured. 5 Apparatus 5.1 Drying room, with suitably controlled temperature, humidity and air circulation, for storing specimens in air and for measuring their l
29、ength. The room shall meet the following requirements. a) Air shall be circulated through the room in a uniform manner, so that the specified conditions are attained adjacent to all specimens under test. b) The temperature in the drying room shall be maintained at (22 2) C. c) The relative humidity
30、in the drying room shall be maintained at (55 5) % at all times. d) The room shall be fitted with recording devices, capable of rapid response to changes in room conditions, which will continuously record the temperature and the relative humidity. The recording detectors shall be verified against a
31、standardized Assmann hygrometer at intervals of time that will assure compliance with the temperature and humidity requirements specified in 5.1, b) and c). NOTE 1 A suitable rapid response device for recording temperature and humidity uses a combined detector with a thin-film capacitor for humidity
32、 and a platinum resistance thermocouple for temperature measurement. Response time for this type of detector is measured in seconds and is virtually instantaneous within the narrow range required for this test method. NOTE 2 Most thermo hygrographs are unsuitable for the purpose, as the response is
33、too slow to detect the full extent of fluctuations, particularly with the hair type of humidity detector. e) The rate of air movement in the drying room shall be determined and controlled by sensors in order to maintain the rate of evaporation at (12 5) ml per 24 h. The evaporation rates shall be de
34、termined by measuring the loss in weight of water in 400 ml low-form beakers of internal diameter (78 5) mm, initially containing approximately 375 g of water at a temperature of (20 2) C. The weight of water in the beaker shall not fall below 325 g. Each beaker shall be placed midway between test s
35、pecimens on the storage racks with the water level at approximately the same height as the top of the specimens. Systematic checks shall be carried out on the sensors or on the evaporation rates by varying the location of the beakers within the drying room at least monthly, or where conditions have
36、changed. The results shall be recorded. f) The requirements for temperature, humidity and evaporation rate apply to each storage position. Only positions that conform to these requirements shall be used for storage of test specimens. g) The drying room shall be fitted with suitable racks for storing
37、 specimens. The racks shall permit free circulation of air around specimens, except for necessary supports, and shall be so situated with respect to the nearest wall or other obstruction that air circulation is not restricted in the intervening BS ISO 1920-8:2009ISO 1920-8:2009(E) ISO 2009 All right
38、s reserved 3space. The horizontal supports shall consist of non-absorptive members having a total bearing width supporting the specimen of not more than 25 mm. 5.2 Moulds, made of non-absorbent material that does not react with cement paste and their internal surfaces; shall have a smooth finish. Th
39、e moulds shall be substantial enough to hold their form without distortion and shall be substantially leak proof. They shall meet the following requirements. 5.2.1 General Each mould shall be provided with a base plate, two end plates and two side plates which are securely fastened to the end plates
40、, and two partially loose end plates which act as gauge stud holders. Each gauge stud holder shall fit inside the end of the mould and shall locate and secure a gauge stud during the setting period of the concrete. Each gauge stud holder shall be held in position against the end plate by a retaining
41、 screw and shall be capable of release after compaction of the concrete. The opposite side plates shall be parallel. The dimensions of the mould shall be one of the following. a) For specimens having dimensions of 75 mm 75 mm 280 mm (see 6.2.2) the distance between the opposite side plates shall be
42、(75 1) mm, and the inside height shall be (75 1) mm; b) For specimens having dimensions of 100 mm 100 mm 400 mm the distance between the opposite side plates shall be (100 1) mm, and the inside height shall be (100 1) mm. 5.2.2 Construction of the mould The mould shall be aligned coaxially along the
43、 central axis of the mould. a) For specimens having dimensions of 75 mm 75 mm 280 mm: the distance between the inner ends of the two studs shall be (250 0,5) mm; the distance between the outer ends of the gauge studs shall be (295 1) mm; gauge studs shall protrude from the gauge stud holders to a di
44、stance of (15 1) mm. b) For specimens having dimensions of 100 mm 100 mm 400 mm: the distance between the inner ends of the two studs shall be (360 0,5) mm; the distance between the outer ends of the gauge studs shall be (420 1) mm; gauge studs shall protrude from the gauge stud holders to a distanc
45、e of (20 1) mm. A suitable form of construction of the moulds is shown in Figure 1. BS ISO 1920-8:2009ISO 1920-8:2009(E) 4 ISO 2009 All rights reserved5.3 Gauge studs, made of stainless steel and conforming to the dimensions shown in Figure 2. The radius of the gauge stud end shall be such as to ass
46、ure compliance to the precision requirements for measuring length changes, as specified in 5.8.1. Gauge studs for horizontal and vertical comparators shall not be interchanged. 5.4 Length gauge, for checking the nominal length between gauge studs (5.3). The length gauge shall be made of metal, and t
47、he specifications shall be as follows. a) For specimens having dimensions of 75 mm 75 mm 280 mm the diameter of the length gauge shall be not less than 6 mm, and the length of the length gauge shall be (250 0,2) mm; b) For specimens having dimensions of 100 mm 100 mm 400 mm the diameter of the lengt
48、h gauge shall be not less than 10 mm, and the length of the length gauge shall be (360 0,2) mm. The ends of the bar shall be flat and perpendicular to its length. 5.5 Means of compaction, consisting of the following. 5.5.1 Tamping bar, compacting bar, straight, made of steel having a rectangular sha
49、pe of approximately 25 mm 10 mm, a length of approximately 600 mm and with a ramming face square with the axis. 5.5.2 Tamping rod, compacting rod of circular cross-section, straight, made of steel, having a diameter of approximately 16 mm, a length of approximately 600 mm and with round ends. 5.5.3 External vibrator, table type with provision for clamping of the mould (5.2), capable of compacting concrete in the moulds. Intern
