BS 812-123-1999 Testing aggregates - Method for determination of alkali-silica reactivity - Concrete prism method《试验集料 碱-硅反应性测定方法 混凝土棱镜法》.pdf

《BS 812-123-1999 Testing aggregates - Method for determination of alkali-silica reactivity - Concrete prism method《试验集料 碱-硅反应性测定方法 混凝土棱镜法》.pdf》由会员分享，可在线阅读，更多相关《BS 812-123-1999 Testing aggregates - Method for determination of alkali-silica reactivity - Concrete prism method《试验集料 碱-硅反应性测定方法 混凝土棱镜法》.pdf（18页珍藏版）》请在麦多课文档分享上搜索。

1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 812-123:1999 Incorpora

2、ting Corrigendum No. 1 ICS 91.100.15 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Testing aggregates Part 123: Method for determination of alkali-silica reactivity Concrete prism methodThis British Standard, having been prepared under the direction of the Sector Committee f

3、or Building and Civil Engineering, was published under the authority of the Standards Committee and comes into effect on 15 June 1999 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference B/502/6 Draft for Comment 88/11922 DC ISBN 0 580 28283 X BS 812-123:

4、1999 Amendments issued since publication Amd. No. Date Comments 10613 Corrigendum No. 1 August 1999 Indicated by a sideline Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/502, Aggregates, to Subcommittee B/502/6, Test

5、methods, upon which the following bodies were represented: British Civil Engineering Test Equipment Manufacturers Association British Geological Survey County Surveyors Society Department of the Environment, Transport and the Regions Represented by the Building Research Establishment Department of t

6、he Environment, Transport and the Regions Highways Agency Quarry Products Association UK Steel Association United Kingdom Accreditation ServiceBS 812-123:1999 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Terms and definitions

7、1 4 Principle 1 5 Sampling 1 6 Apparatus 1 7 Materials 2 8 Preparation of aggregate test portions 6 9 Mix design 6 10 Temperature and humidity conditions 7 11 Preparation of test prisms 7 12 Storage and measurement 8 13 Calculation and expression of results 9 14 Test report 9 Annex A (informative) P

8、rocedure for checking the uniformity of the temperature within the room or cabinet used for storing the test prisms at (38 2)8C1 0 Annex B (normative) Proforma for calculating batch masses 10 Annex C (informative) Precision 11 Bibliography 12 Figure 1 Example of stainless steel reference stud 3 Figu

9、re 2 Example of reference stud providing hemispherical bearing 3 Figure 3 Example of length comparator 4 Figure 4 Container to provide humid environment around concrete prism 5 Table 1 Mix proportions by volume for cement and dry aggregates 6 Table 2 Temperature and humidity requirements 7 Table B.1

10、 Proforma for calculating batch masses for a 7 l concrete mix from volume proportions 10 Table C.1 Precision of the determination of the expansion of concrete prisms 11ii BSI 08-1999 BS 812-123:1999 | Foreword This British Standard has been prepared under the direction of Technical Committee B/502.

11、It specifies a method for the measurement of expansion of concrete produced by alkali-silica reaction involving specific aggregate combinations, and is based on the measurement of the length change of concrete prisms containing a high level of alkali that are made from the aggregate under test. This

12、 test method was originally published as DD 218:1995, which is withdrawn. Annex A is informative, annex B is normative and annex C is informative. A British Standard does not purport to include all necessary provisions of a contract. Users of British Standards are responsible for their correct appli

13、cation. 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, pages 1 to 11, a blank page, an inside back cover and a back cover. The BSI copyright notice displayed

14、throughout this document indicates when the document was last issued. Sidelining in this document indicates the most recent changes by amendment. BSI 08-1999 1 BS 812-123:1999 | 1 Scope This British Standard specifies a method of measuring the expansion of concrete produced by alkali-silica reaction

15、 involving specific combinations of aggregates. The method is designed as an accelerated laboratory test for a specific combination of aggregates and is not considered to be a performance test for concrete. NOTE Aggregates are usually tested in the same combination as when they are actually used. Wh

16、en the aggregate combination to be used is not decided, however, the test sample of aggregate is tested in combination with both an inert aggregate and an aggregate geologically similar to itself in proportions specified in the method. This procedure provides a generally satisfactory assessment of t

17、he aggregate by accommodating any pessimum value which it may possess. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of this British Standard. For dated references, subsequent amendments to, or re

18、visions of, any of these publications do not apply. For undated references, the latest edition of the cited publication referred to applies. BS 12, Specification for Portland cement. BS 410, Specification for test sieves. BS 812-2, Testing aggregates Part 2: Methods for the determination of density.

19、 BS 812-100, Testing aggregates Part 100: General requirements for apparatus and calibration. BS 812-101, Testing aggregates Part 101: Guide to sampling and testing aggregates. BS 812-102:1989, Testing aggregates Part 102: Methods for sampling. BS 812-117, Testing aggregates Part 117: Method for det

20、ermination of water-soluble chloride salts. BS 882, Specification for aggregates from natural sources for concrete. BS 1881-108:1983, Testing concrete Part 108: Method for making test cubes from fresh concrete. BS 1881-131, Testing concrete Part 131: Methods for testing cement in a reference concret

21、e. BS EN 196-6, Methods of testing cement Part 6: Determination of fineness. BS EN 196-21:1992, Methods of testing cement Part 21: Determination of chloride, carbon dioxide and alkali content of cement. 3 Terms and definitions For the purposes of this part of BS 812, the terms and definitions given

22、in BS 812-100, BS 812-101 and BS 812-102 apply. 4 Principle Concrete test prisms are prepared from the aggregate combination under test, and stored for a period of 52 weeks in conditions which would promote any potential alkali-silica reaction. During this time measurements are made at intervals to

23、determine whether any expansion has occurred. In order to promote the development of any expansive forces and to ensure that slowly reacting aggregates are detected in the 52-week period, the test is accelerated by: a) formulating the concrete to possess a higher than average cement and alkali conte

24、nt; b) storing the prisms at high humidity and a comparatively high temperature (388C) to increase the rate of the chemical reaction. NOTE If expansion exceeding an agreed or specified limit is recorded in the test, or atypical expansion is obtained in routine monitoring of an aggregate source, the

25、individual test specimen exhibiting the highest expansion may be examined to confirm that alkali-silica reaction is the main cause of that expansion. Suitable procedures are to be found in The Diagnosis of Alkali-Silica Reaction 1. 5 Sampling The samples of coarse and fine aggregates used for the te

26、st (the laboratory samples) shall be taken in accordance with the procedure specified in BS 812-102:1989, clause 5. NOTE The recommendations given in BS 812-102 are primarily intended for sampling from a stockpile of aggregate. Where aggregate is being sampled from a quarry it is important to ensure

27、 that the samples obtained for use in the test are satisfactorily representative of the sources concerned. 6 Apparatus 6.1 General All apparatus shall conform to the general requirements of BS 812-100. 6.2 Sample divider, of size appropriate to the maximum particle size to be handled, or alternative

28、ly, a flat shovel and a clean, flat, hard surface (e.g. a metal tray), for use in quartering. NOTE A suitable divider is the riffle box illustrated in BS 812-102:1989, Figure 2. 6.3 Test sieves, conforming to BS 410, of the size and apertures appropriate to the nominal size of aggregates to be teste

29、d. 6.4 Balance, of minimum capacity 5 kg, readable to 1 g. 6.5 Balance, of minimum capacity 100 g, readable to 0.01 g. 6.6 Four steel moulds, with cavities suitable for casting concrete prisms of lengths (250 50) mm. No two cavities shall differ in length by more than 5 mm and the cross-sections sha

30、ll be (75 2) mm by (75 2) mm. The moulds shall have the facility for casting stainless steel reference studs into the mid-points of the end faces of the prisms.2 BSI 08-1999 BS 812-123:1999 1) A reference cement with a certified alkali content can be obtained from Building Research Establishment, Ga

31、rston, Watford, WD2 7JR. The reference studs shall be mounted inside the mould before casting the prisms. The studs shall either have smooth conical recesses into which a 6 mm ball may be located, as shown in Figure 1, or shall provide a 3 mm radius hemispherical bearing, as shown in Figure 2. NOTE

32、The use of stainless steel grade 316 S11, as specified in BS 970-1:1991, or a grade of similar quality, is recommended for the manufacture of reference studs. 6.7 Length comparator, incorporating a measuring device with graduations not greater than 0.002 mm and having a maximum error of 0.002 mm. Th

33、e arrangement of the comparator and the range of displacement of the gauge shall be such that specimens can be inserted and removed without damage or undue pressure to the prisms, reference studs or measuring device. NOTE 1 To allow for typical variations of the prisms and the reference rod, a minim

34、um range of displacement of the measuring device of 15 mm is recommended. The gauge shall be mounted rigidly in a vertical orientation in a stoutly constructed measuring frame. NOTE 2 An example of a measuring frame incorporating a mechanical gauge is shown in Figure 3. Similar devices utilizing dig

35、ital or electronic gauges may be used. Each stud locator of the comparator shall have a stainless steel hemisphere which can be placed into the reference studs in the test prisms. Alternatively, if reference studs which provide hemispherical bearings are used, the comparator shall have recessed coni

36、cal cups which can be located onto the studs. NOTE 3 Attention is drawn to the need to ensure the long term stability and accuracy of comparators. In particular, mechanical gauges should be checked for evidence of wear, and electrical gauges for drift. 6.8 Reference length gauge rod, with ends machi

37、ned to match the shape of the reference studs in the prisms. For example, for use with the recessed studs, the rod shall have smooth conical recesses; for studs with the hemispherical bearing, the rod shall have hemispherical ends of 3 mm radius. The rod shall be made from material which has a coeff

38、icient of linear thermal expansion, in the range 08C to 1008C, of not more than 23 10 24 % per8C. NOTE 1 The material known as “Invar” which is a nickel-iron alloy containing about 36 % nickel, has been found to be satisfactory. NOTE 2 The gauge length of the rod slowly diminishes with time as the c

39、ontact surfaces wear. It is therefore recommended that a second similar rod be stored for use as a primary standard for periodically checking the regular rod, or for use as a spare if necessary. The gauge length of the rod shall not differ from the mean gauge length of the four prisms by more than 5

40、 mm. 6.9 Concrete mixing equipment, as specified in BS 1881-131. 6.10 Vibrating table, as specified in BS 1881-108:1983, 3.3. 6.11 Containers, for maintaining a high relative humidity around the wrapped prisms during storage. NOTE A suitable design of container is shown in Figure 4. 6.12 Twill-weave

41、 cotton cloth, (240 30) g/m 2 dry, at least 10 mm wider, but not more than 20 mm wider, than the length of the prisms. 6.13 Polyethylene lay flat tubing, 500 gauge, 180 mm wide. 6.14 Polyethylene bags, 500 gauge, approximately 500 mm3 250 mm. 6.15 Temperature-controlled room or cabinet, capable of b

42、eing maintained at a temperature of (38 2)8C throughout its storage space. 6.16 Temperature-recording equipment, capable of keeping a record of the temperature at one point within the storage facility (see 6.14). 6.17 Temperature-controlled room, capable of being maintained at a temperature of (20 2

43、)8C and at a relative humidity of not less than 50 %. 6.18 Ventilated oven, thermostatically controlled at a temperature of (110 5)8C, for drying the aggregate. 6.19 Nine maximum/minimum thermometers. 6.20 Steel rule, graduated in millimetres. 7 Materials 7.1 Potassium sulfate, of analytical reagent

44、 quality. 7.2 High-alkali Portland cement, with a certified alkali content 1) . NOTE For testing other than reference and referee testing, cement to the following specification may be used as an alternative to the certified reference cement. Portland cement conforming to BS 12, having a total alkali

45、 content, expressed as equivalent sodium oxide (the sum of the contents of Na 2 O and 0.658 K 2 O), of not less than 0.8 % and not more than 1.0 % as determined in accordance with BS EN 196-21:1992, clause 7 (see 9.3). WARNING Safety precautions should be taken when preparing and handling test prism

46、s made from mixes prepared from Portland cement. In particular, eyes should be protected during all mixing operations and gloves worn during mixing and whenever the test prisms are handled. 7.3 Deionized water. 7.4 Mixing water, of potable quality. BSI 08-1999 3 BS 812-123:1999 Dimensions in millime

47、tres 8 Circular grooves about 0.75 mm x 0.75 mm deep or similar helical thread Smooth conical recess 6 B.A. thread 10 6 9 5 7 90 5 Figure 1 Example of stainless steel reference stud Dimensions in millimetres Spherical end, smooth finish 22 R 3 Figure 2 Example of reference stud providing hemispheric

48、al bearing4 BSI 08-1999 BS 812-123:1999 Dimensions in millimetres Rods 120 12 350 Figure 3 Example of length comparator BSI 08-1999 5 BS 812-123:1999 Dimensions in millimetres Top View Section View Measuring Insert Container with air tight lid Clearance between prism and plastic mesh not less than 5

49、 and not more than 20 Concrete prism (nominal 75 x 75 x 250) Prism wrapped in damp cotton cloth and further double wrapped in polyethylene Blotting paper held against side of container by plastic mesh Measuring Insert Spacer (Not less than 5 clearance) Water (minimum depth 20) Support to hold prism clear of Water A Detail A Figure 4 Container to provide humid environment around concrete prism6 BSI 08-1999 BS 812-123:1999 2) Suitable non-reactive, coarse and fine aggregates are available from Building Res