ACI 211 2-1998 Standard Practice for Selecting Proportions for Structural Lightweight Concrete《轻量结构混凝土比例选择的标准规范》.pdf

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1、ACI 211.2-98 (Repproved 2004) supersedes ACI 211.2-91 and became effectiveMarch 1, 1998.Copyright 1998, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic ormechani

2、cal device, printed, written, or oral, or recording for sound or visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission inwriting is obtained from the copyright proprietors.211.2-1ACI Committee Reports, Guides, Standard Practices, andCommentaries are intend

3、ed for guidance in planning,designing, executing, and inspecting construction. Thisdocument is intended for the use of individuals who arecompetent to evaluate the significance and limitations of itscontent and recommendations and who will acceptresponsibility for the application of the material it

4、contains.The American Concrete Institute disclaims any and allresponsibility for the stated principles. The Institute shall notbe liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocuments. If items found in this document are desired by theArchi

5、tect/Engineer to be a part of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.It is the responsibility of the user of this document toestablish health and safety practices appropriate to the specificcircumstances involved with its use. A

6、CI does not make anyrepresentations with regard to health and safety issues and theuse of this document. The user must determine theapplicability of all regulatory limitations before applying thedocument and must comply with all applicable laws andregulations, including but not limited to, United St

7、atesOccupational Safety and Health Administration (OSHA)health and safety standards.Standard Practice for Selecting Proportions for Structural Lightweight Concrete (ACI 211.2-98)Reported by ACI Committee 211Edward A. Abdun-NurStanley G. Barton*Leonard W. BellGeorge R. U. BergStanley J. Blas, Jr.Pegg

8、y M. CarrasquilloRamon L. CarrasquilloMartyn T. ConreyJames E. CookRussell A. Cook*William A. CordonWayne J. CostaKenneth W. DayCalvin L. Dodl*Donald E. GrahamGeorge W. Hollon*William W. Hotaling, Jr.Robert S. JenkinsPaul KliegerFrank J. LahmStanley H. LeeGary R. MassRichard C. MeiningerRichard W. N

9、arvaLeo P. NicholsonJames E. OliversonJames S. PierceSandor PopovicsSteven A. RaganHarry C. RobinsonJere H. RoseJames A. ScherocmanJames M. Shilstone, Sr.George B. SouthworthAlfred B. SpamerPaul R. Stodola*Michael A. TaylorStanley J. Virgalitte*William H. VoelkerJack W. WeberDean J. White, IIMilton

10、H. Wills, Jr.Francis C. WilsonRobert L. Yuan*Members of Subcommittee B who prepared this standard.ACI 211.2-98(Reapproved 2004)This standard describes, with examples, two methods for propor-tioning and adjusting proportions of structural grade concretecontaining lightweight aggregates. The weight (p

11、ycnometer) methoduses a specific gravity factor determined by a displacement pycnom-eter test on the aggregates (Method 1). The weight method alsoemploys the specific gravity factor to estimate the weight per yd3 of thefresh concrete. The damp, loose volume method uses the cementcontent-strength rel

12、ationship for the design of all lightweight and sandlightweight concrete (Method 2). Examples are given for systematiccalculation of batch weights; effective displaced volumes; and adjust-ment to compensate for changes in aggregate moisture content; aggre-gate proportions; cement content; slump, air

13、 content, or bothKeywords: absorption; adsorption; air content; air entrainment; cementcontent; coarse aggregate; fine aggregate; fineness modulus; grading; light-weight aggregate; mixture proportioning; moisture; slump test; specificgravity factor.Committee that voted on reapproval, 2004William L.

14、Barringer David A. Crocker Richard D. Hill Jan Olek Ava ShypulaMuhammed P. A. Basheer D. Gene Daniel David L. Hollingsworth H. Celik Ozyildirim Jeffrey F. SpeckCasimir Bognacki Francois de Larrard Said Iravani Dipak T. Parekh William X. SypherMichael J. Boyle Donald E. Dixon Tarif M. Jaber James S.

15、Pierce Stanley J. VirgalitteMarshall L. Brown Calvin L. Dodl Robert S. Jenkins Steven A. Ragan Woodward L. VogtRamon L. Carrasquillo Darrell F. Elliot Gary Knight Royce J. Rhoads Michael A. WhisonantJames E. Cook Michael R. Gardner Colin L. Lobo John P. Ries Dean J. White, IIJohn F. Cook John T. Gut

16、hrie Howard P. Lux Shelley R. Sheetz Richard M. WingRaymond A. Cook G. Terry Harris, Sr. Gary R. Mass James M. Shilstone, Sr.Jay R. PresteraSecretaryMichael BoyleChairDavid A. CrockerChair, Subcommittee BFrank A. KozeliskiChairEd T. McGuireSecretaryG. Michael RobinsonChair, Subcommittee B211.2-2 ACI

17、 STANDARD PRACTICECONTENTSChapter 1Introduction, p. 211.2-21.1Purpose1.2ScopeChapter 2Factors affecting proportioning of lightweight-aggregate concrete, p. 211.2-22.1Aggregates (absorption and moisture content)2.2Aggregates (gradation)2.3Water-cementitious material ratio2.4Air entrainmentChapter 3Es

18、timating first trial mixtureproportions, p. 211.2-43.1General3.2Method 1: Weight method (specific gravity pycnometer)3.3Method 2: Volumetric method (damp, loose volume)Chapter 4Adjusting mixture proportions,p. 211.2-164.1General4.2Method 1: Weight method (specific gravity pycnometer)4.3Method 2: Vol

19、umetric method (damp, loose volume)4.4Adjustment procedures4.5Controlling proportions in the fieldChapter 5References, p. 211.2-185.1Referenced standards and reportsAppendix ADetermination of specific gravity factors of structural lightweight aggregate,p. 211.2-19Appendix BDetermination of structura

20、l light-weight coarse aggregate absorption, p. 211.2-20CHAPTER 1INTRODUCTION1.1PurposeThe purpose of this standard is to provide generally appli-cable methods for selecting and adjusting mixture propor-tions for structural lightweight concrete. These methods arealso applicable to concrete containing

21、 a combination oflightweight and normalweight aggregate.1.2ScopeDiscussion in this standard is limited to structural grade,lightweight aggregates, and structural lightweight-aggregateconcrete. Structural lightweight-aggregate concrete isdefined as concrete which: (a) is made with lightweightaggregat

22、es conforming to ASTM C 330, (b) has a compressivestrength in excess of 2500 psi (17.2 MPa) at 28 days of agewhen tested in accordance with methods stated in ASTM C330, and (c) has an equilibrium weight not exceeding 115 lb/ft3(1842 kg/m3) as determined by ASTM C 567. Concrete inwhich a portion of t

23、he lightweight aggregate is replaced bynormalweight aggregate is within the scope of this standard.When normalweight fine aggregate is used, it should conformto the requirements of ASTM C 33. The use of pozzolanic andchemical admixtures is not covered in this standard.CHAPTER 2FACTORS AFFECTINGPROPO

24、RTIONING OF LIGHTWEIGHTAGGREGATE CONCRETE2.1Aggregates (absorption and moisture content)2.1.1 The principal factors necessitating modification ofproportioning and control procedures for lightweight-aggregateconcrete, compared with normalweight concrete, are thegreater absorptions and the higher rate

25、s of absorption ofmost lightweight aggregates.2.1.2 Damp aggregates are preferable to dry aggregates attime of mixing, as they tend to absorb less water duringmixing and therefore reduce the possibility of loss of slumpas the concrete is being mixed, transported, and placed.Damp aggregates have less

26、 tendency to segregate in storage.Absorbed water is accounted for in the mixture-propor-tioning procedure.2.1.3 When concrete is made with lightweight aggregatesthat have low initial moisture contents (usually less than 8 to10%) and relatively high rates of absorption, it may be desir-able to mix th

27、e aggregates with one-half to two-thirds of themixing water for a short period before adding cement,admixtures, and air-entraining admixture to minimize slumploss. The supplier of the particular aggregate should beconsulted regarding the necessity for such predampeningand for mixing procedure.2.1.4

28、Concrete made with saturated lightweight aggre-gates may be more vulnerable to freezing and thawing thanconcrete made with damp or dry lightweight aggregates,unless the concrete is allowed to lose its excess moistureafter curing, before such exposure, and has developedadequate strength to resist fre

29、ezing.2.1.5 When producing trial batches in the laboratory usingthe specific gravity method, the specific gravity of the light-weight aggregate should be determined at the moisturecontent anticipated before use.2.1.6 For most concrete mixture proportions to be prac-tical, aggregate proportions shoul

30、d be listed at a moisturecondition readily attainable in the laboratory and in the field.In structural lightweight concrete, the main problem isaccounting properly for the moisture in (absorbed), and on(adsorbed), the lightweight aggregate particles as well as forthe effects of absorption for a spec

31、ific application. Tradition-ally, concrete technologists have assumed, for aggregatemoisture content correction purposes, that aggregates are inone of the four conditions at the time of use. These fourconditions are shown in Fig. 2.1.Most concrete mixture proportions are reported withaggregates in e

32、ither saturated surface-dry (SSD) condition oroven-dry (OD) condition. In the field, aggregates are usuallyin the air-dry (AD) or wet condition. Lightweight aggregate,however, usually presents a unique situation. Most structurallightweight-aggregate concrete mixture proportions arereported in the OD

33、 condition; however, in the field they arenot SSD, but in a damp or wet condition. This condition isusually achieved by sprinkling, soaking, thermal quenching,or vacuum saturation. The result is sometimes referred to asthe “as-is” condition (Fig. 2.2).SELECTING PROPORTIONS FOR STRUCTURAL LIGHTWEIGHT

34、 CONCRETE 211.2-3The main problem for the concrete technologist is to havean easy method of using field data to convert the oven-drylaboratory trial proportions to proportions in the “as-is”moisture condition.2.2Aggregates (gradation)2.2.1 Grading of the fine and coarse aggregates and theproportions

35、 used have an important effect on the concrete. Awell-graded aggregate will have a continuous distribution ofparticle sizes, producing a minimum void content and willrequire a minimum amount of cement paste to fill the voids.This will result in the most economical use of cement andwill provide maxim

36、um strength with minimum volumechange due to drying shrinkage.2.2.2 In general, the largest total volume of aggregate inthe concrete is achieved:(a) when the coarse aggregate is well graded from thelargest to the smallest sizes;(b) when the particle is rounded to cubical in shape; and(c) when the su

37、rface texture is least porous.Conversely, concrete containing coarse aggregates thattend to be angular in shape, more porous in surface texture,and possibly deficient in one or more particle sizes, willrequire a smaller volume of aggregates.These same factors of grading, particle shape, and texturea

38、lso affect the percentage of fine aggregate required with aminimum percentage of fine aggregate being associatedwith a rounded or cubical shape and smooth texture. It iscommon that when a well-graded, normalweight sand isused to replace lightweight fine aggregate, the proportionof coarse lightweight

39、 aggregate may be increased. Theproportion of coarse aggregate should approach themaximum consistent with workability and placeability,unless tests indicated that a lesser proportion providesoptimum characteristics.In some cases, strength may be increased by reducing thenominal maximum size of the a

40、ggregate without increasingthe cement content.2.2.3 For normalweight aggregates, the bulk specific gravitiesof fractions retained on the different sieve sizes are nearlyequal. Percentages retained on each size indicated by weightgive a true indication of percentages by volume. The bulkspecific gravi

41、ty of the various size fractions of lightweightaggregate, however, usually increases as the particle sizedecreases. Some coarse aggregate particles may float onwater, whereas material passing a No. 100 sieve (0.15 mm)may have a specific gravity approaching that of normalweightsand. It is the volume

42、occupied by each fraction, and not theweight of material retained on each sieve, that determines thevoid content and paste content, and influences workability ofthe concrete. For a fine aggregate with a specific gravity of1.89, the percentages retained on each sieve and finenessmodulus, by weight an

43、d by volume, are computed forcomparison in the example illustrated in Table 2.1.A fineness modulus of 3.23 by volume in the exampleindicates a considerably coarser grading than that normallyassociated with the fineness modulus of 3.03 by weight.Therefore, lightweight aggregates require a largerperce

44、ntage of material retained on the finer sieve sizes on aweight basis than do normalweight aggregates to provide anequal size distribution by volume.2.2.4 As indicated in Section 1.2, concrete containingsome normalweight aggregates, such as normalweight sand,is classified as lightweight concrete, pro

45、vided the strengthand unit weight requirements are met. The use of normal-weight sand usually results in some increase in strength andmodulus of elasticity. These increases, however, are made atthe sacrifice of increased weight. The mixture proportionsFig. 2.2“As-is” condition.Fig. 2.1States of mois

46、ture in aggregate.Table 2.1Comparison of fineness modulus by weight and volume for typical lightweight aggregateSieve size, no.Opening, in. (mm)Percent retained by weightCumulative percent retained by weightBulk specificgravity,SSD basisPercentretained byvolumeCumulative percent retained byvolume4 0

47、.187 (4.75) 0 0 0 08 0.0937 (2.38) 22 22 1.55 26 2616 0.0469 (1.19) 24 46 1.78 25 5130 0.0234 (0.59) 19 65 1.90 19 7050 0.0117 (0.30) 14 79 2.01 13 83100 0.0059 (0.15) 12 91 2.16 10 93Pan 9 100 2.40 7 100Note: Fineness modulus (by weight) = 3.03; fineness modulus (by volume) = 3.23.211.2-4 ACI STAND

48、ARD PRACTICEselected, therefore, should consider these properties inconjunction with the corresponding effects on the overalleconomy of the structure.2.3Water-cementitious material ratio2.3.1 Method 1Lightweight-aggregate concrete may beproportioned by Method 1 (weight method, specific gravitypycnom

49、eter) on the basis of an approximate water-cementi-tious material ratio (w/cm) relationship when the absorptionof the lightweight aggregate is known or determined, asdescribed later in Appendix A. This method utilizes the factthat the sum of the weights per unit volume of all ingredientsin a mixture is equal to the total weight of the same mixture.If the weight of the particular concrete per unit volume,which contains a particular aggregate, is known or can beestimated from the specific gravity factor of the aggregate,the weight of the lightweight aggrega