ACI 304 3R-1996 Heavyweight Concrete Measuring Mixing Transporting and Placing《重混凝土 测量、搅拌、运输和浇筑》.pdf

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1、304.3R-1ACI 304.3R-96 supersedes ACI 304.3R-89 and became effective January 23, 1996.Copyright 1997, 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 ormechanical

2、 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.ACI Committee Reports, Guides, Standard Practices, and Commentariesare intended for gui

3、dance in planning, designing, executing, and inspect-ing construction. This document is intended for the use of individualswho are competent to evaluate the significance and limitations ofits content and recommendations and who will accept responsibilityfor the application of the material it contain

4、s. The American ConcreteInstitute disclaims any and all responsibility for the stated principles. TheInstitute shall not be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contract documents.If items found in this document are desired by the Architect/

5、Engineer tobe a part of the contract documents, they shall be restated in mandatorylanguage for incorporation by the Architect/Engineer.Presents recommended methods and procedures for measuring, mixing,transporting, and placing heavyweight concretes that are used principallyfor radiation shielding i

6、n nuclear construction. Also covered are recommen-dations on cement, heavyweight aggregates, water, and admixtures. Mixtureproportioning of heavyweight concrete is discussed. Recommendations forpreplaced-aggregate heavyweight concrete are also included, together withsuitable grout proportions. Mixin

7、g equipment, form construction, placingprocedures, and methods of consolidation are described. Quality control,inspection, and testing are emphasized, and a list of references is included.Keywords: admixtures; aggregates; barite; cements; concrete construction;concretes; consolidation; construction

8、equipment; conveying; density(mass/volume); formwork (construction); grout; heavyweight aggregates;heavyweight concretes; ilmenite; limonite; magnetite; mass concrete; mate-rials handling; mix proportioning; mixing; placing; quality control; pre-placed-aggregate concrete; radiation shielding; segreg

9、ation.CONTENTSChapter 1General considerations, p. 304.3R-2Chapter 2Materials, p. 304.3R-22.1Cement2.2Aggregate2.3Mixing water2.4Admixtures2.5Proprietary premixed mortarChapter 3Concrete characteristics, p. 304.3R-43.1Physical properties3.2Mixture proportioningChapter 4Equipment, p. 304.3R-5Chapter 5

10、Formwork, p. 304.3R-55.1Conventional method5.2Preplaced-aggregate methodChapter 6Placement, p. 304.3R-56.1Conventional method6.2Preplaced-aggregate methodChapter 7Quality control, p. 304.3R-67.1Samples and tests7.2Cement7.3Aggregate7.4Admixtures7.5Control tests7.6InspectionChapter 8References, p. 30

11、4.3R-78.1Specified and/or recommended references8.2Cited referencesACI 304.3R-96(Reapproved 2004)Heavyweight Concrete:Measuring, Mixing, Transporting, and PlacingReported by ACI Committee 304Robert A. Kelsey, Roger E. Phares James S. Pierce*Chairman Vice Chairman Subcommittee ChairmanDavid J. Akers*

12、 Thomas A. Johnson Paul E. ReinhartJames E. Bennett, Jr. Samuel A. Kalat* Royce J. RhoadsCasimir Bognacki John C. King Kenneth L. SaucierTianxia Cao* William C. Krell Donald L. SchlegelJames L. Cope Gary R. Mass Paul R. StodolaDaniel Green Patrick McDowell William X. SypherNeil R. Guptill Dipak T. P

13、arekh Robert E. TobinTerence C. Holland*Members of the subcommittee who prepared revisions to the report.304.3R-2 ACI COMMITTEE REPORTCHAPTER 1GENERAL CONSIDERATIONSThe procedures for measuring, mixing, transporting, andplacing heavyweight concrete are similar to those used in con-ventional concrete

14、 construction; however, special expertiseand thorough planning are necessary for the successful com-pletion of this type of concrete work. The use of heavyweightconcrete in construction is a specialized field, and it is advis-able that the work be undertaken by qualified personnel.1Heavyweight concr

15、ete is used in counterweights of bas-cule and lift bridges, but it is generally used in radiationshielding structures and differs from normal weight concreteby having a higher density and special compositions to im-prove its attenuation properties. When the heavyweight con-crete is used to absorb ga

16、mma rays, the density and materialscosts are of prime importance.1When heavyweight shieldingconcrete is used to attenuate neutrons, sufficient material oflight atomic weight, which produces hydrogen, should be in-cluded in the concrete mixture.2Some aggregates are usedbecause of their ability to ret

17、ain water of crystallization at el-evated temperatures, which ensures a source of hydrogen notnecessarily available in heavyweight aggregates.CHAPTER 2MATERIALS2.1CementCements conforming to ASTM C 150, which would besuitable for conventional concrete and produce the requiredphysical properties, are

18、 suitable for use in heavyweight con-crete. Low-alkali cement should be used when alkali-reac-tive constituents are present in the aggregates and a moderateor low-heat cement should be used for massive members inaccordance with Chapter 14, Massive Concrete, of ACI 301.To avoid high and rapid heat of

19、 hydration and resultantcracking, it is advisable not to use Type III cement or accel-erators unless the concrete temperature is controlled by spe-cially designed refrigeration systems. Blended hydrauliccements meeting the requirements of ASTM C 595 also maybe used in lieu of portland cements. Howev

20、er, blended hy-draulic cements should be used only if their use does not re-duce the density of the concrete below the specified limit.Storage of cementitious materials should be in accordancewith ACI 304R.2.2AggregateThorough examination and evaluation of heavyweight ag-gregate sources are necessar

21、y to obtain material suitable forthe type of shielding required.3These sources are limited, anda material survey should be conducted to determine availabil-ity, chemical and physical qualities, and service records. Sam-ples for test should be taken under the supervision of theowners representative t

22、o meet requirements of ASTM C 637.The suppliers sources should be inspected to evaluate rockcomposition, abrasion resistance, and density since theseproperties may vary from one location to another within a de-posit. The purchaser must realize that mineral ores are not asuniform as normal weight con

23、crete aggregates and make ap-propriate allowances. Purchase orders should specify strictlimits on allowable deviations for each property and makespecific provisions for remedial action in the event the toler-ances are not met.Density and compositionAggregate density and compo-sition for radiation sh

24、ielding are described in ASTM C 638and specified in ASTM C 637. Some typical properties forshielding aggregates are shown in Table 1. Coarse metallic aggregate for preplaced-aggregate con-crete should have 100 percent retained on a 9.5-mm (3/8-in)sieve and be reasonably free of thin, flat, or elonga

25、ted piecesof metal. Maximum particle size is usually limited to 11/2-in.(37.5-mm). Fine metallic aggregate should consist of commercialchilled-iron or steel shot or ground iron, meeting SAE J444a. Metallic aggregates should have a specific gravity of7.50 or greater and be clean and free from foreign

26、 coatingsof grease, oil, machine shop compounds, zinc chromate,loose scale, and dirt.Shipment and storageAggregate should be shipped,handled, and sorted in a manner that will insure little loss offines, no contamination by foreign material, and no signifi-cant aggregate breakage or segregation.Aggre

27、gates may be shipped in heavy wooden boxes, wa-tertight bags, steel containers, or in bulk by railroad cars orTable 1 Typical aggregates*Heavy Aggregate SourceCompositionSpecific GravityPercent by weightCoarse pieces Fine sand Iron Fixed waterIlmenite Que. Fe, Ti, O, etc. 4.50 4.60 40 0Limonite-goet

28、hite UT, MI 2Fe2O3-3H2O3.453.705 1Magnetite NV, WY Fe3O4, etc. 4.50 4.55 60 1Magnetite MT Hydrous iron 4.30 4.34 60 2-5Barite TN 92 percent BaSO44.20 4.24 1-10 0Barite NV 90 percent BaSO44.28 4.31 1 0Ferrophosphorous*Fe3P, Fe2P, FeP 6.30 6.28 70 0Steel aggregate Punchings, sheared bars 7.78 99 0Iron

29、 shot Cold chilled shot 7.50 99 0*Source: Reference 4.Material water-saturated, with its surface dry.Other sources may be available.In some instances the composition may be more important than the specific gravity if the aggregates attenuation characteristics are good.*Ferrophosphorous when used in

30、portland cement concrete will generate flammable and possibly toxic gases that can develop high pressures if confined.HEAVYWEIGHT CONCRETE: MEASURING, MIXING, TRANSPORTING, AND PLACING 304.3R-3Table 2 Typical proportions for heavyweight concreteConventionally placed concreteDensity(unit weight), lb/

31、ft3(kg/m3)Compressive strength,age 3 months psi (MPa)Cement,lb/ft3(kg/m3)Heavy aggregate, lb/ft3(kg/m3)Mix water, lb/ft3(kg/m3)Water content*lb/ft3 (kg/m3)Fine Coarse Minimum Maximum300(4810)5000(34.5)23.5(376)Iron shot195(3120)12.0(192)3.5(56)12.0(192)Magnetite70(1120)300(4810)4870(33.6)24.1(386)Fe

32、rrophospho-rous92(1470)Ferrophospho-rous171(2740)12.7(203)3.6(58)12.7(203)262(4200)5350(36.9)23.7(380)Ferrophospho-rous70(1120)Ferrophospho-rous70(1120)12.8(205)3.6(58)12.8(205)Barite35(560)Barite50(800)232(3720)6500(44.8)24.3(389)Magnetite86(1380)Magnetite110(1760)11.5(184)5.7(91)13.5(216)222(3560)

33、6000(41.4)19.3(309)Barite86(1380)Barite105(1680)11.6(186)2.9(46)11.6(186)219(3510)6500(44.8)24.9(399)Hydrous iron ore82(1310)Hydrous iron ore100(1600)12.0(192)9.2(147)17.5(280)190(3040)5750(39.6)20.9(335)Serpentine50(800)Magnetite106(1700)13.0(208)9.1(146)19.0(304)Preplaced-aggregate method346(5540)

34、3000(207)20.6(330)Magnetite44(700)Punchings270(4330)11.3(181)3.5(56)11.8(189)300(4810)5000(34.5)19.8(317)Magnetite42(670)Magnetite67(1070)10.9(175)4.1(66)12.0(192)Punchings160(2560)263(4210)6000(41.4)22.2(356)Limonite28(450)Limonite60(960)12.2(195)13.0(208)21.9(351)Punchings140(2240)262(4200)4800(33

35、.1)19.8(317)Magnetite42(670)Magnetite122(1950)10.9(175)4.7(75)12.6(202)Punchings67(1070)245(3920)19.5(312)Serpentine23(370)Serpentine48(769)9.8(157)Punchings145(2320)244(3910)5000(34.5)17.5(280)Magnetite37(590)Magnetite180(2880)9.7(155)4.8(77)11.9(191)215(3440)5000(34.5)22.7(364)Limonite29(460)Limon

36、ite28(450)12.5(200)10.9(175)20.0(320)Magnetite122(1950)*Maximum water content is water weight when concrete is wet. Minimum water content is amount left after drying to constant weight at 185 F (85 C). Differ-ence between the maximum water content and the amount of mix water added is the water of cr

37、ystallization held by the aggregate. The difference between the minimum water content and the water of crystallization is the water retained by the hardened cement paste.304.3R-4 ACI COMMITTEE REPORTtrucks. Storage should be as near the batch plant as possible,and protected from moisture. The net we

38、ight of aggregate ineach container should be plainly marked on the container.2.3Mixing waterWater and ice to be used in heavyweight concrete shouldconform to the requirements of ACI 301 or ASTM C 94. Inaddition, water should be clean and free from injuriousamounts of oil, acid, alkali, organic matte

39、r, or other deleteri-ous substances.2.4AdmixturesConventionally placed heavyweight concrete may contain achemical admixture meeting ASTM C 494 requirements forType A or D. Type F or G may also be used to improve theplaceability and reduce the tendency for segregation. WhenType F or G is used, cautio

40、n must be used to be sure the mix-ture is not over-vibrated and the heavyweight particles segre-gated. Air-entraining admixtures are not generally used inconcrete that is not exposed to freezing and thawing becausetheir use would tend to decrease the density of the concrete.However, if the concrete

41、mixtures have sufficient density toallow 4 percent entrained air, there are definite advantages tobe realized: reduced bleeding, greater workability, and a morehomogeneous concrete. Preplaced-aggregate grout shouldcontain a fluidifier conforming to ASTM C 937. Admixturesshould be stored in accordanc

42、e with requirements of ACI304R.Fly ash meeting the requirements of ASTM C 618 may beused to enhance the workability of heavyweight mixtures.Other mineral admixtures such as natural pozzolans and sil-ica fume also may be used. These admixtures should meetthe requirements of ASTM C 618 and C 1240, res

43、pectively.However, their effect on the concrete density must be evalu-ated and the admixtures omitted if the resulting concretedensity is lower than that specified.2.5Proprietary premixed mortarIron mortar concretes produced commercially by manu-facturers for shielding concrete have been tested and

44、foundadequate. However, these materials should be tested prior touse for density, compressive strength, and the necessaryproperties for shielding.CHAPTER 3CONCRETE CHARACTERISTICS3.1Physical propertiesHigh modulus of elasticity, low coefficient of thermal ex-pansion, and low elastic and creep deform

45、ations are idealproperties for both conventional structural concrete andheavyweight concrete. Heavyweight concrete is used whenthe thickness of the concrete is limited. High compressivestrengths may be required if heavyweight concrete is to besubjected to high temperatures and stress levels. Thisstr

46、ength requirement may necessitate the use of a low water-cement ratio, and if placing conditions are difficult, a highcement content will also be required for workability, or aType F or G chemical admixture may be used. Heavyweightconcrete with high cement content and low water-cement ra-tio may exh

47、ibit increased creep and shrinkage, and in a mas-sive concrete placement could generate high temperatures atearly ages causing undesirable localized cracking from thethermally induced stresses and strains.4When structural con-siderations require this cracking potential to be eliminated, itwill be ne

48、cessary to use appropriate temperature controlmeasures that could include precooling or postcooling theconcrete, or both, as described in ACI 207.1R, ACI 207.2R,and ACI 224R.3.2Mixture proportioningProcedures outlined in ACI 211.1 should be used for mix-ture proportioning. Typical proportions for he

49、avyweightconcrete are shown in Table 2.Conventionally placed heavyweight concreteThe concretemixture should be proportioned to provide the desired compres-sive strength, density, and adequate workability. Also, thechemical constituents and fixed water content of the resultingmixture must provide satisfactory shielding properties.5(Fixedwater is water necessary to supply hydrogen for shielding.)Preplaced-aggregate heavyweight concreteCoarse ag-gregate for heavyweight preplaced-aggregate concrete may bea heavyweight mineral aggregate,