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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 method This British Standard, having been prepared under the direction of the Sector Committee
3、for 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.DateComments 10613 CorrigendumNo.1 August 1999Indicated 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 meth
5、ods, 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 the E
6、nvironment, Transport and the Regions Highways Agency Quarry Products Association UK Steel Association United Kingdom Accreditation Service BS 812-123:1999 BSI 08-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Normative references1 3Terms and definitions1 4Principle
7、1 5Sampling1 6Apparatus1 7Materials2 8Preparation of aggregate test portions6 9Mix design6 10Temperature and humidity conditions7 11Preparation of test prisms7 12Storage and measurement8 13Calculation and expression of results9 14Test report9 Annex A (informative) Procedure for checking the uniformi
8、ty of the temperature within the room or cabinet used for storing the test prisms at (382) 8C10 Annex B (normative) Proforma for calculating batch masses10 Annex C (informative) Precision11 Bibliography12 Figure 1 Example of stainless steel reference stud3 Figure 2 Example of reference stud providin
9、g hemispherical bearing3 Figure 3 Example of length comparator4 Figure 4 Container to provide humid environment around concrete prism5 Table 1 Mix proportions by volume for cement and dry aggregates6 Table 2 Temperature and humidity requirements7 Table B.1 Proforma for calculating batch masses for a
10、 7 l concrete mix from volume proportions10 Table C.1 Precision of the determination of the expansion of concrete prisms11 ii BSI 08-1999 BS 812-123:1999 | Foreword This British Standard has been prepared under the direction of Technical Committee B/502. It specifies a method for the measurement of
11、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 test method was originally published as DD 2
12、18:1995, 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 application. Compliance with a British Standard do
13、es 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 throughout this document indicates when the d
14、ocument was last issued. Sidelining in this document indicates the most recent changes by amendment. BSI 08-19991 BS 812-123:1999 | 1 Scope This British Standard specifies a method of measuring the expansion of concrete produced by alkali-silica reaction involving specific combinations of aggregates
15、. 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. NOTEAggregates are usually tested in the same combination as when they are actually used. When the aggregate combination to be used is not
16、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 the aggregate by accommodating any pessimum valu
17、e 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 revisions of, any of these publications do not ap
18、ply. 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. BS 812-100, Testing aggregates Part 100: Gener
19、al 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 determination of water-soluble chloride salts. BS
20、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 concrete. BS EN 196-6, Methods of testing cement Part
21、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 in BS 812-100, BS 812-101 and BS 812-102 apply.
22、 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 determine whether any expansion has occurred. I
23、n 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 content; b) storing the prisms at high humidity and
24、a comparatively high temperature (38 8C) to increase the rate of the chemical reaction. NOTEIf 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 individual test specimen exhibiting the highest
25、 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 test (the laboratory samples) shall be taken in a
26、ccordance with the procedure specified in BS 812-102:1989, clause 5. NOTEThe 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 that the samples obtained for use in the test a
27、re 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 alternatively, a flat shovel and a clean, flat, hard surfac
28、e (e.g. a metal tray), for use in quartering. NOTEA 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 tested. 6.4 Balance, of minimum capacity 5 kg, readabl
29、e 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 (25050) mm. No two cavities shall differ in length by more than 5 mm and the cross-sections shall be (752) mm by (752) mm. The moulds shall have
30、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, Garston, Watford, WD2 7JR. The reference studs shall b
31、e 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. NOTEThe use of stainless steel grade 316 S11, as specifie
32、d 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 of0.002 mm. The arrangement of the comparator and the range of displ
33、acement 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 1To allow for typical variations of the prisms and the reference rod, a minimum range of displacement of the measuring device of 15
34、mm is recommended. The gauge shall be mounted rigidly in a vertical orientation in a stoutly constructed measuring frame. NOTE 2An example of a measuring frame incorporating a mechanical gauge is shown in Figure 3. Similar devices utilizing digital or electronic gauges may be used. Each stud locator
35、 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 conical cups which can be located onto the studs. NOTE 3Atte
36、ntion 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 machined to match the shape of the reference studs in the pris
37、ms. 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 coefficient of linear thermal expansion, in the range 0 8C to
38、100 8C, of not more than 2 3 1024% per 8C. NOTE 1The material known as Invar which is a nickel-iron alloy containing about 36 % nickel, has been found to be satisfactory. NOTE 2The gauge length of the rod slowly diminishes with time as the contact surfaces wear. It is therefore recommended that a se
39、cond 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 mm. 6.9 Concrete mixing equipment, as specified in BS 1881
40、-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. NOTEA suitable design of container is shown in Figure 4. 6.12 Twill-weave cotton cloth, (24030) g/m2dry, at least 10 mm wider, but no
41、t 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 mm 3 250 mm. 6.15 Temperature-controlled room or cabinet, capable of being maintained at a temperature of (382) 8C throughout its st
42、orage 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 (202) 8C and at a relative humidity of not less than 50 %. 6.18 Ven
43、tilated oven, thermostatically controlled at a temperature of (1105) 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 quality. 7.2 High-alkali Portland cement, with a certified al
44、kali content1). NOTEFor 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 content, expressed as equivalent sodium oxide (the sum of the co
45、ntents of Na2O and 0.658 K2O), 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 prisms made from mixes prepared from Portland cement. In particular, eyes
46、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 08-19993 BS 812-123:1999 Dimensions in millimetres 8 Circular grooves about 0.75 mm x 0.75 mm deep or similar helica
47、l 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 hemispherical bearing 4 BSI 08-1999 BS 812-123:1999 Dimensions in millimetres Rod
48、s 120 12 350 Figure 3 Example of length comparator BSI 08-19995 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 and not more than 20 Concrete prism (nominal 75 x 75 x 250) Prism wra
49、pped 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 prism 6 BSI 08-1999 BS 812-123:1999 2)Suitable non-reactive, coarse and fine aggregates are available from Building Research Establishment, Garston, Watford, WD2 7JR. 8 Preparation of aggregate tes
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