《BS-12-1996.pdf》由会员分享,可在线阅读,更多相关《BS-12-1996.pdf(18页珍藏版)》请在三一文库上搜索。
1、BRITISH STANDARD BS 12:1996 Specification for Portland cement Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 12:1996 This British Standard, having been prepared under the direction of the Sector Board for Building and Civil Engineering,
2、was published under the authority of the Standards Board and comes into effect on 15 May 1996 BSI 11-1998 First published December 1904 Second edition June 1907 Third edition August 1910 Fourth edition March 1915 Fifth edition August 1920 Sixth edition October 1925 Seventh edition November 1931 Eigh
3、th edition July 1940 Ninth edition November 1947 Tenth edition March 1958 Eleventh edition July 1971 Twelfth edition June 1978 Thirteenth edition April 1989 Fourteenth edition November 1991 Fifteenth edition May 1996 The following BSI references relate to the work on this standard: Committee referen
4、ce B/516/6 Draft for comment 94/100796 DC ISBN 0 580 25343 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/516, Cement and lime, to Subcommittee B/516/6, Cement specifications, upon which the following bodies were rep
5、resented: British Aggregate Construction Materials Industries British Cement Association British Precast Concrete Federation British Ready Mixed Concrete Association Cement Admixtures Association Cementitious Slag Makers Association County Surveyors Society Department of the Environment (Building Re
6、search Establishment) Department of Transport (Highways Agency) Electricity Association National Rivers Authority Quality Ash Association Society of Chemical Industry Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 20
7、06, Uncontrolled Copy, (c) BSI BS 12:1996 BSI 11-1998i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2References1 3Definitions1 4Cement1 5Constituents1 6Composition and notation2 7Compressive strength2 8Physical properties3 9Chemical properties3 10Marking3 11Information t
8、o be provided3 12Sampling and testing for acceptance inspection at delivery3 13Special Portland cements4 Annex A (informative) Conformity criteria (cement manufacturers autocontrol)5 Annex B (informative) Compositional requirements for all cement types8 Annex C (informative) Product guidance9 Table
9、1 Compressive strength2 Table 2 Chemical properties4 Table 3 Acceptance inspection limits4 Table A.1 Minimum testing frequencies6 Table A.2 Parameters determining the conformity procedure7 Table A.3 Major defects7 Table A.4 Acceptability constant kA8 Table A.5 Acceptable number of defects cA8 Table
10、B.1 Extreme compositional possibilities9 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 12:1996 ii BSI 11-1998 Foreword This edition of this British Standard has been prepared by Subcommittee B/516/6.
11、It introduces technical changes but it does not reflect a full review or revision of the standard, which will be undertaken in due course. It is based on the work of Technical Committee 51, Cement and building limes, of the European Committee for Standardization (CEN), which has prepared a European
12、Prestandard specification for cements published as DD ENV 197-1. As an intrinsic part of this activity, CEN has published EN 196, a series of methods of testing cement, which the UK is implementing to replace the relevant Parts of BS 4550. In consequence, this British Standard specifies requirements
13、 in terms of the test procedures in EN 196. It supersedes BS 12:1991 which is withdrawn. The requirements for compressive strength, physical and chemical properties are specified as characteristic values and conformity is assessed by means of a statistical procedure for continuous inspection operate
14、d by the cement manufacturer (autocontrol) (see annex A). This includes the concept of “major defects” which are “likely to reduce materially the usability of the cement for its intended purpose”. However, DD ENV 197-1 is considered to be inappropriate for the manufacture of cement in the UK and the
15、 annex therefore incorporates several footnotes identifying specific aspects. In particular, it is assumed, for this edition of this British Standard, that some limits are required for acceptance inspection. Clause 12 therefore gives appropriate values which in several cases are more stringent than
16、those for major defects given in annex A. The strength requirements are based on the BS EN 196-1 mortar prism test at 28 days. In addition to the two classes of standard strength, 32.5 and 42.5, each with two subclasses of early strength, this British Standard includes two higher classes of standard
17、 strength, 52.5 and 62.5, to cover all Portland cements available in the UK (see Table 1). It should be noted that for prescribed or standard mixes, as described in BS 5328-1, unless the cement content is increased appropriately, the use of cements of the 32.5 standard strength class will lead to co
18、ncrete of lower compressive strength and may reduce durability, compared with cements of a higher strength class. This revision introduces the following changes. a) Compositional requirements are expressed as a percentage of the total mass of the constituents but excluding calcium sulfate and any ad
19、ditives. This departure from the traditional method of calculation in the UK is fully explained in annex B. b) Requirements are not specified for fineness, but the note to 13.1 describes how specialist users in the UK can order a controlled fineness Portland cement having a small agreed range of fin
20、eness. c) Guidance on the use of cement has been retained and attention is drawn to the safety precautions recommended in annex C when working with cement. Cement will partially hydrate when exposed to water vapour; annex C also includes guidance on storage. Other British Standards for cement, i.e.
21、BS 146, BS 4027, BS 4246, BS 6588, BS 6610 and BS 7583, have been revised at the same time. Product certification. Purchasers are recommended to specify cement manufactured and supplied to a nationally recognized third party product certification scheme. Licensed Copy: sheffieldun sheffieldun, na, F
22、ri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 12:1996 BSI 11-1998iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of
23、itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will b
24、e indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 12:1996 BSI
25、11-19981 1 Scope This British Standard1) specifies requirements for the composition and the manufacture and for the strength, physical and chemical properties of Portland cement as characteristic values. Requirements for marking, provision of information, sampling and testing for acceptance at deliv
26、ery and for special Portland cements are also specified. It specifies the procedures for the manufacturers autocontrol system to ensure conformity. 2 References 2.1 Normative references This British Standard incorporates, by reference, provisions from specific editions of other publications. These n
27、ormative references are made at the appropriate points in the text and the publications are listed on the inside back cover. Subsequent amendments to, or revisions of, any of these publications apply to this British Standard only when incorporated in it by updating or revision. 2.2 Informative refer
28、ences This British Standard refers to other publications 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
29、 British Standard the definitions in BS 6100-6.1 apply together with the following. 3.1 characteristic value that value of a property corresponding to an acceptable percentage of defects, generally 10 % but 5 % for the lower strength limits 4 Cement NOTE 1Cement is a hydraulic binder, i.e. it is a f
30、inely ground inorganic material which, when mixed with water, forms a paste which sets and hardens by means of hydration reactions and processes and which, after hardening, retains its strength and stability even under water. Cement conforming to this British Standard shall, when appropriately batch
31、ed and mixed with aggregate and water, be capable of producing mortar or concrete which retains workability for a sufficient time and shall after defined periods attain specified strength levels and also possess long-term volume stability. NOTE 2Hydraulic hardening of cement conforming to this Briti
32、sh Standard is primarily due to the hydration of calcium silicates2), but other chemical compounds may also participate in the hardening process, e.g. aluminates. The sum of the proportions of reactive calcium oxide (CaO)3) and reactive silicon dioxide (SiO2)4) shall be not less than 50 % (m/m). Cem
33、ent conforming to this British Standard ultimately consists of individual small grains of different materials but it shall be statistically homogeneous in composition. A high degree of uniformity in all cement properties shall be obtained through continuous mass production processes, in particular a
34、dequate grinding and homogenization processes. NOTE 3Qualified and skilled personnel and the facilities to test, evaluate and adjust product quality are essential for producing cement conforming to this British Standard. During the cement manufacturing process and its control, the composition of the
35、 cement shall be kept within the limits specified in this British Standard. 5 Constituents 5.1 Portland cement clinker Portland cement clinker is a hydraulic material which shall consist of not less than two-thirds by mass of calcium silicates (CaO)3SiO2 and (CaO)2SiO2), the remainder containing alu
36、minium oxide (Al2O3), iron oxide (Fe2O3) and other oxides. The ratio by mass (CaO)/(SiO2) shall be not less than 2.0. The content of magnesium oxide (MgO) shall not exceed 5.0 % (m/m). 1) Other types of cement standardized in the UK are specified in BS 146, BS 915, BS 1370, BS 4027, BS 4246, BS 4248
37、, BS 6588, BS 6610 and BS 7583. 2) There are also cements whose hardening is mainly due to other compounds, e.g. calcium aluminate in high alumina cement. 3) Reactive calcium oxide (CaO) is considered to be only that fraction of the CaO which under normal hardening conditions can form calcium silica
38、te hydrates or calcium aluminate hydrates. To evaluate this fraction, the total CaO content is to be reduced by the part calculated as calcium carbonate (CaCO3) on the basis of the measured carbon dioxide (CO2) content and the part calculated as calcium sulfate (CaSO4) on the basis of the measured s
39、ulfate content (expressed as SO3) disregarding the SO3 taken up by alkalis. 4) Reactive silicon dioxide (SiO2) is defined as that fraction of the SiO2 which, after treatment with hydrochloric acid (HCl), is soluble in boiling potassium hydroxide (KOH) solution. The quantity of reactive SiO2 is deter
40、mined by subtracting from the total SiO2 content (see 13.9 of BS EN 196-2:1995) that fraction of the SiO2 contained in the insoluble residue (see clause 10 of BS EN 196-2:1995), both on a dry basis. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:28:39 GMT+00:00 2006, Uncontrolled Copy, (c
41、) BSI BS 12:1996 2 BSI 11-1998 Portland cement clinker shall be made by burning, at least to sintering, a precisely specified mixture of raw materials (raw meal, paste or slurry) containing CaO, SiO2, Al2O3 and small quantities of other materials. The raw meal, paste or slurry shall be finely divide
42、d, intimately mixed and therefore homogeneous. 5.2 Minor additional constituents Minor additional constituents if present shall be one or more of granulated blastfurnace slag, natural pozzolana, pulverized-fuel ash (fly ash) or filler. NOTE 1The minor additional constituents should not promote corro
43、sion of the reinforcement or impair the properties of the cement or of the mortar or concrete made from the cement. NOTE 2Granulated blastfurnace slag is made by rapid cooling of a slag melt of suitable composition, as obtained in smelting iron ore in a blastfurnace. Natural pozzolanas are usually s
44、ubstances of volcanic origin or sedimentary rocks with appropriate chemical and mineralogical composition. Fly ash is obtained by electrostatic or mechanical precipitation of dust-like particles from the flue gases from furnaces fired with pulverized hard coal. Ash obtained by other methods is not c
45、onsidered in this British Standard. For the purposes of this British Standard, the term “filler” covers any natural or artificial inorganic mineral materials other than blastfurnace slag, natural pozzolana or pulverized-fuel ash, e.g. calcareous materials, which, after appropriate preparation, due t
46、o their particle size distribution, improve the physical properties of the cement (such as workability or concrete bleeding). 5.3 Calcium sulfate Calcium sulfate shall be added in small quantities to the other constituents of cement during its manufacture in order to control setting. NOTECalcium sul
47、fate can be gypsum (calcium sulfate dihydrate, CaSO42H2O), hemihydrate (partially dehydrated gypsum, CaSO4H2O) or anhydrite (anhydrous calcium sulfate, CaSO4) or any mixture of them. Gypsum and anhydrite are found naturally. Calcium sulfate is also available as a by-product of certain industrial pro
48、cesses. 5.4 Additives If the total quantity of additives exceeds 1.0 % (m/m) of the cement, the type and quantity shall be stated on the packaging and/or on the delivery note. NOTE 1These additives are constituents not specified in 5.1 to 5.3 which are added to improve the manufacture or the propert
49、ies of the cement, e.g. grinding aids. They should not promote corrosion of the reinforcement or impair the properties of the cement or of the mortar or concrete made from the cement. NOTE 2The total quantity of additives should not exceed 1.0 % (m/m). 6 Composition and notation 6.1 Composition The composition of the “nucleus” (see B.1) of Portland cement shall be as follows: NOTEFor clarity in definition, calcium sulfate (see 5.3) and additives (see 5.4) are excluded. The final cement is to be understood as the nucleus plus the necessary calcium sulfate
链接地址:https://www.31doc.com/p-3731907.html