BS 1881-131-1998 Testing concrete Methods for testing cement in a reference concrete《混凝土试验 混凝土试样水泥含量测试方法》.pdf

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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 1881 : Part 131 : 1998

2、 Incorporating Amendment No. 1 ICS 91.100.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Testing concrete Part 131. Methods for testing cement in a reference concreteThis British Standard, having been prepared under the direction of the Sector Board for Building and Civil

3、Engineering, was published under the authority of the Standards Board and comes into effect on 15 May 1998 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference B/517/1 Draft for comment 96/109327 DC ISBN 0 580 28689 4 BS 1881 : Part 131 : 1998 Amendments

4、issued since publication Amd. No. Date Text affected 10470 July 1999 Indicated by a sideline in the margin Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/517, Concrete, to Subcommittee B/517/1, Concrete production and

5、testing, upon which the following bodies were represented: Association of Lightweight Aggregate Manufacturers British Cement Association British Civil Engineering Test Equipment Manufacturers Association British Precast Concrete Federation Ltd. Cement Admixtures Association Cementitious Slag Makers

6、Association Chartered Institution of Water and Environmental Management Construction Confederation County Surveyors Society Department of the Environment, Transport and the Regions Department of the Environment, Transport and the Regions (Building Research Establishment) Federation of Piling Special

7、ists Institute of Concrete Technology Institution of Structural Engineers National House-building Council Quarry Products Association Society of Chemical Industry United Kingdom Quality Ash AssociationBS 1881 : Part 131 : 1998 BSI 07-1999 i Contents Page Committees responsible Inside front cover For

8、eword ii Method 1 Scope 1 2 References 1 3 Definitions 1 4 Principle 1 5 Apparatus and materials 1 6 Proportioning 1 7 Temperature and humidity conditions 2 8 Procedure for mixing 2 9 Testing the concrete 2 10 Report 3 Annexes A (normative) Coarse aggregate 6 B (normative) Sand 6 C (informative) Alt

9、ernative mixing 9 Tables 1 Batch masses 2 2 Temperature and humidity conditions 2 3 Ages for strength tests 3 4 Dimensions 4 A.1 Coarse aggregate grading 6 B.1 Composition of mortar 7 Figures 1 Typical rotating pan concrete mixer 4 2 Suitable trowel 5 B.1 Grading of sand fractions for concrete cubes

10、 8ii BSI 07-1999 BS 1881 : Part 131 : 1998 | | Foreword This Part of BS 1881 has been prepared by Subcommittee B/517/1. It supersedes BS 4550 : Part 4 : 1978 and BS 4550 : Part 5 : 1978 which are withdrawn. It also supersedes clause 1 of BS 4550 : Section 3.4 : 1978. The transfer of this test to BS

11、1881 allows its continued use in assessing the strength produced by a cement in a specified concrete. A procedure for mixing concrete based on that used in BS 1881 : Part 125 has been introduced as the reference procedure for mixing in this Part of BS 1881. The procedure described in BS 4550 : Secti

12、on 3.4 has been retained in this standard as an alternative procedure to allow comparison with previous tests (see annex C). It has become common practice to measure the slump of the concrete produced for this test to assess the effect of the cement on consistence. A procedure has been added to this

13、 standard (see 9.1). It has been shown that deviations from the specified raw materials, mixer, mixing procedure and curing conditions affect the slump result. As it may not always be possible to use the apparatus and materials specified in this British Standard, substitution of other apparatus and

14、materials is permitted, but any such deviation should be reported detailing, where possible, the effect of the deviation. A British Standard does not purport to include all necessary provisions of a contract. Users of British Standards are responsible for their correct application. Summary of pages

15、This document contains a front cover, an inside front cover, pages i and ii, pages 1 to 10, an inside back cover and a back cover. The BSI copyright notice displayed throughout this document indicates when the document was last issued. BSI 07-1999 1 BS 1881 : Part 131 : 1998 Method 1 Scope This Brit

16、ish Standard gives methods for testing cement in a reference concrete. It includes provisions for the laboratory conditions, the mixer, materials and mix proportions together with the procedures for mixing and testing the concrete. 2 References 2.1 Normative references This British Standard incorpor

17、ates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or rev

18、isions of the publications apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This British Standard refers to other publ

19、ications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this standard the definitions given in BS 1881 : Par

20、t 102, Part 108, Part 111, Part 114, Part 115, Part 116 and Part 125 apply. 4 Principle A concrete is made with the cement to be tested, using specified constituent materials in specified proportions and mixed by machine. The consistence of the concrete is determined by its slump and its strength is

21、 measured by compressive strength tests on 100 mm concrete cubes. 5 Apparatus and materials 5.1 Cube moulds, of 100 mm size conforming to BS 1881 : Part 108. 5.2 Concrete mixer, comprising a rotating mixer pan with a contra-rotating mixing paddle and a scraper blade. The dimensions and tolerances sh

22、all be as shown in figure 1. The mixing pan shall rotate at (18 1) r/min. The mixing paddle (offset from the pan centre) shall rotate at (90 5) r/min. The mixing paddle and scraper blade shall be spring loaded to ensure they do not jam during mixing. Simple and positive means of vertical adjustment

23、shall be provided on the mountings of the mixing paddle and scraper blade. The mixer shall either be fitted with an automatic timing device or a stop clock shall be provided. 5.3 Slump cone, conforming to BS 1881 : Part 102. 5.4 Slump rod, conforming to BS 1881 : Part 102. 5.5 Slump baseplate, confo

24、rming to BS 1881 : Part 102. 5.6 Slump scoop, conforming to BS 1881 : Part 102. 5.7 Trowel, having a cast steel blade. NOTE. A suitable type is shown in figure 2. 5.8 Compacting equipment, either a compacting bar, a vibrating hammer or a vibrating table in accordance with 3.3 of BS 1881 : Part 108 :

25、 1983. 5.9 Curing tank, conforming to BS 1881 : Part 111. NOTE. Specimens made with high alumina or super sulfated cements should not be placed in the same tank as specimens made with Portland cements. 5.10 Balance, capable of weighing to the nearest 1 g. 5.11 Compression testing machine, of suitabl

26、e capacity for the test conforming to BS 1881 : Part 115. NOTE. The lower limit of verification for the scale range used should be below the expected maximum load on any specimen tested on the scale range. 5.12 Coarse aggregate, conforming to the requirements of annex A. 5.13 Sand, conforming to the

27、 requirements of annex B. 5.14 Water, deionized or distilled. 6 Proportioning The masses of the individual materials for batches of sufficient volume to produce three, six, nine or 12 cubes are given in table 1.2 BSI 07-1999 BS 1881 : Part 131 : 1998 Table 1. Batch masses Constituent material Propor

28、tion by mass Mass g Mix 1 Mix 2 Mix 3 Mix 4 3 cubes 6 cubes and/or 1 slump 9 cubes and/or 3 cubes and 1 slump 12 cubes and/or 6 cubes and 1 slump Cement 1.0 1100 5 2200 5 3200 5 4200 5 Sand 2.5 A (2.36 mm to 1.18 mm) 275 5 550 5 800 5 1050 5 B (1.18 mm to 600mm) 550 5 1100 5 1600 5 2100 5 C (600mm t

29、o 300mm) 825 5 1650 5 2400 5 3150 5 D (300mm to 150mm) 690 5 1375 5 2000 5 2625 5 E (150mmt o9 0m m) 410 5 825 5 1200 5 1575 5 Coarse aggregate 3.5 3850 10 7700 10 11200 10 14700 10 Water 0.60 660 5 1320 5 1920 5 2520 5 7 Temperature and humidity conditions Before use, all materials and apparatus sh

30、all be brought to the same temperature as the air in the mixing room, by storing them in the room for a sufficient time. The temperature throughout the entire test procedure shall be controlled about a mid-point of 208C with permitted variation as shown in table 2. The minimum relative humidity shal

31、l be as given in table 2. Table 2. Temperature and humidity conditions Situation Permitted temperature variation Minimum relative humidity 8C% Mixing room 25 0 Moist curing chamber 29 0 Water curing tank 2 Compression testing room 25 0 NOTE 1. A record should be kept for reference purposes of the ac

32、tual temperature and relative humidity conditions. NOTE 2. The high humidity required in moist air curing rooms is normally produced by spraying water as a fine aerosol. The bacterium Legionella pneumophila is widespread in nature and is present in water systems of many buildings. Scale in pipework

33、and chemical nutrients in the water supply may encourage growth of this organism which multiplies at temperatures above 208C. Inhaling infected aerosols is a known route for transmission of legionellosis. It is therefore advisable to maintain cold water supplies below 208C where possible and to stor

34、e hot water above 608C. Cold water supplies may be disinfected by chlorination to a least 5 mg/l free chlorine. Regular periodic checking for the presence of Legionella species in industrial water supplies is a sensible precaution. 8 Procedure for mixing NOTE. The procedure in this clause is based o

35、n that given in BS 1881 : Part 125. An alternative based on the procedure in BS 4550 : Section 3.4 is given in annex C. This alternative method is retained to allow comparison with historical records. Add in order, about half the coarse aggregate, the sand and the remaining coarse aggregate by sprea

36、ding them evenly in the pan. Start the mixer and run it for about 15 s. Continue mixing and add about half the water during the next 15 s. After mixing for a total of (120 5) s, stop the mixer and leave the contents covered for (300 10) s. Record the time of commencement and add the cement by spread

37、ing it in an even layer over the aggregate. Start the mixer and mix for about 30 s. Stop the mixer and immediately clean off any material adhering to the mixer blades into the pan. Without delay, recommence mixing and slowly add the remaining mixing water within the next 30 s. Continue mixing after

38、all materials have been added for a further (120 5) s. After completion of mixing, leave the contents of the mixer covered for (300 10) s then remix for (30 5) s. Transfer the whole of the batch onto the sampling tray. Ensure that no more than a light covering of slurry is left adhering to the mixer

39、. Turn the concrete over a few times with the trowel to remove any slight segregation. 9 Testing the concrete 9.1 Consistence The consistence shall be determined by carrying out a slump test in accordance with BS 1881 : Part 102. Testing shall be completed within 5 min of completion of remixing. BSI

40、 07-1999 3 BS 1881 : Part 131 : 1998 9.2 Strength 9.2.1 Batches Make batches of three, six, nine or 12 cubes. NOTE. For factory production control only, batches of three cubes may be made, one or two for testing at any of the specified ages. 9.2.2 Filling the moulds Place the moulds on a rigid horiz

41、ontal surface or on the vibrating table and approximately half fill with concrete, by means of the scoop, then compact. Repeat the operation to fill the moulds. 9.2.3 Compacting The specimens shall be compacted either by compacting bar or by vibrator. a) Using the compacting bar Compact each layer w

42、ith 35 strokes of the compacting bar. When compacting each layer, distribute the strokes of the compacting bar in a uniform manner over the cross-section of the mould, and ensure that the compacting bar does not forcibly strike the bottom of the mould when compacting the first layer nor penetrate si

43、gnificantly the first layer when compacting the second layer. b) Using the vibrator When compacting each layer by means of the vibrating hammer or vibrating table, use applied vibration of the minimum duration necessary to achieve full compaction of the concrete. Cease vibration as soon as the surfa

44、ce of the concrete becomes relatively smooth and has a glazed appearance. Record the duration of vibration. 9.2.4 Finishing After the top layer has been compacted, smooth it level with the top of the mould using the trowel, and wipe clean the outside of the mould. Complete the entire process within

45、15 min from the completion of mixing. 9.2.5 Storage of cubes 9.2.5.1 General requirements Immediately after preparation, place the moulds in a single layer on a level surface in the moist curing chamber. Cover the exposed tops of the cubes with an impervious sheet (e.g. of clean thin rubber or plast

46、ics, or lightly oiled steel) making contact with the upper edge of the mould. After (24 0.5) h mark the cubes for later identification and remove them from the moulds. Immediately submerge all the cubes in water, except those to be tested at one day, in the curing tank and arrange them in such a way

47、 that the temperature variation specified in table 2 is not exceeded. Leave the cubes in the curing tank until just prior to the testing. NOTE. If the concrete has not achieved sufficient strength to be handled without fear of damage after 24 h, delay the demoulding for a further period of 24 h but

48、state this fact in the test report. 9.2.5.2 Special requirements for testing at one day Mark and demould cubes to be tested at one day (15 to 20) min before testing and cover with a damp cloth so that they remain in the moist condition until tested. 9.2.6 Testing for strength 9.2.6.1 The age of each

49、 test is calculated from the time of adding the cement to the other materials. Test three cubes at an age selected from table 3 within the limits given. Table 3. Ages for strength tests Age Limit days h 12 4 0.5 37 2 1 7 168 2 28 672 4 9.2.6.2 Determine the compressive strength of the cubes in accordance with BS 1881 : Part 116. 9.2.6.3 Calculate the average of the individual results of the set of three cubes tested at the same age, and express the result to the nearest 0.5 N/mm 2 . If