ACI 309R-2005 Guide for Consolidation of Concrete《混凝土的凝固指南》.pdf

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1、ACI 309R-05 became effective August 5, 2005 and supersedes ACI 309R-96.Copyright 2005, 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 device, print

2、ed, written, or oral, or recording for sound or visual reproductionor for use in any knowledge or retrieval system or device, unless permission in writingis obtained from the copyright proprietors.ACI Committee Reports, Guides, Standard Practices, andCommentaries are intended for guidance in plannin

3、g,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 contains.The American Conc

4、rete 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 theArchitect/Engineer to be a part

5、 of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.309R-1Guide for Consolidation of ConcreteReported by ACI Committee 309ACI 309R-05Consolidation is the process of removing entrapped air from freshly placedconcrete. Several methods and

6、techniques are available, the choicedepending mainly on the workability of the mixture, placing conditions,and degree of air removal desired. Some form of vibration is usuallyemployed.This guide includes information on the mechanism of consolidation andgives recommendations on equipment, characteris

7、tics, and procedures forvarious classes of construction.The paired values stated in inch-pound units and hard SI units are usuallynot exact equivalents. Therefore, each system is to be used independently ofthe other. Combining values from the two systems may result in nonconfor-mance with this guide

8、.Keywords: box out; compaction; consistency; consolidation; placing,rheology; rodding; segregation; spading; tamping; vibration; vibrator;workability.CONTENTSChapter 1General, p. 309R-2Chapter 2Effect of mixture proportions on consolidation, p. 309R-32.1Mixture proportions2.2Workability and consiste

9、ncy2.3Workability requirementsChapter 3Methods of consolidation, p. 309R-43.1Manual methods3.2Mechanical methods3.3Methods used in combinationChapter 4Consolidation of concrete by vibration, p. 309R-54.1Vibratory motion4.2Process of consolidationChapter 5Equipment for vibration, p. 309R-65.1Internal

10、 vibrators5.2Form vibrators5.3Vibrating tables5.4Surface vibrators5.5Vibrator maintenanceNeil A. Cumming Kenneth C. Hover H. Celik OzyildirimTimothy P. Dolen Garry R. Mass Steven A. RaganChiara F. Ferraris Bryant Mather*Mike ThompsonSteven H. Gebler Larry D. Olson Bradley K. ViolettaGlenn A. Heimbru

11、ch*Deceased.Richard E. MillerChairJerome H. FordSubcommittee Chair309R-2 ACI COMMITTEE REPORTChapter 6Forms, p. 309R-136.1General6.2Sloping surfaces6.3Surface blemishes6.4Form tightness6.5Forms for external vibrationChapter 7Recommended vibration practices for general construction, p. 309R-157.1Gene

12、ral7.2Procedure for internal vibration7.3Adequacy of internal vibration7.4Vibration of reinforcement7.5Revibration7.6Form vibration7.7Consequences of improper vibrationChapter 8Structural concrete, p. 309R-198.1Design and detailing prerequisites8.2Mixture requirements8.3Internal vibration8.4Form vib

13、ration8.5Tunnel liningsChapter 9Mass concrete, p. 309R-209.1Mixture requirements9.2Vibration equipment9.3Forms9.4Vibration practices9.5Roller-compacted concreteChapter 10Normal-density concrete floor slabs, p. 309R-2210.1Mixture requirements10.2Equipment10.3Structural slabs10.4Slabs on ground10.5Hea

14、vy-duty industrial floors10.6Vacuum dewateringChapter 11Pavements, p. 309R-2411.1General11.2Mixture requirements11.3Equipment11.4Vibration procedures11.5Special precautionsChapter 12Precast products, p. 309R-2712.1General12.2Mixture requirements12.3Forming material12.4Choice of consolidation method1

15、2.5Placing methodsChapter 13Structural low-density concrete,p. 309R-2813.1General13.2Mixture requirements13.3Behavior of structural low-density concrete duringvibration13.4Consolidation equipment and procedures13.5FloorsChapter 14High-density concrete, p. 309R-2914.1General14.2Mixture requirements14

16、.3Placing techniquesChapter 15Self-consolidating concrete,p. 309R-2915.1GeneralChapter 16Quality control and quality assurance, p. 309R-2916.1General16.2Adequacy equipment and procedures16.3Checking equipment performanceChapter 17Consolidation of test specimens,p. 309R-3117.1Strength17.2Density17.3A

17、ir content17.4Consolidating very stiff concrete in laboratoryspecimensChapter 18Consolidation in congested areas,p. 309R-3218.1Common placing problems18.2Consolidation techniquesChapter 19References, p. 309R-3319.1Referenced standards and reports19.2Cited referencesAppendixFundamentals of vibration,

18、 p. 309R-35A.1Principles of simple harmonic motionA.2Action of a rotary vibratorA.3Vibratory motion in the concreteCHAPTER 1GENERALFreshly placed unconsolidated concrete contains excessiveand detrimental entrapped air. If allowed to harden in thiscondition, the concrete will be porous and poorly bon

19、ded tothe reinforcement. It will have low strength, high permeability,and poor resistance to deterioration. It may also have a poorappearance. The mixture should be consolidated if it is tohave the properties desired and expected of concrete.Consolidation is the process of inducing a closer arrangem

20、entof the solid particles in freshly mixed concrete or mortarduring placement by the reduction of voids, usually by vibra-tion, centrifugation (spinning), rodding, spading, tamping, orsome combination of these actions.Stiffer mixtures require greater effort to achieve properconsolidation. By using c

21、ertain chemical admixtures (ACI212.3R), consistencies requiring reduced consolidationeffort can be achieved at lower water content. As the watercontent of the concrete is reduced, concrete strength, perme-ability, and other desirable properties improve, provided thatthe concrete is properly consolid

22、ated. Alternatively, theGUIDE FOR CONSOLIDATION OF CONCRETE 309R-3cementitious materials content can be lowered, reducing thecost while maintaining the same strength. If adequateconsolidation is not provided for these stiffer mixtures, thestrength of the in-place concrete decreases rapidly.Equipment

23、 and methods are now available for fast andefficient consolidation of concrete over a wide range ofplacing conditions. Concrete with a relatively low watercontent can be readily molded into an unlimited variety ofshapes, making it a highly versatile and economicalconstruction material. When good con

24、solidation practicesare combined with good formwork and good form releaseagents, concrete surfaces have a highly pleasing appearance(Fig. 1.1(a) through (c).CHAPTER 2EFFECT OF MIXTURE PROPORTIONS ON CONSOLIDATION2.1Mixture proportionsConcrete mixtures are proportioned to provide theworkability neede

25、d during construction and the requiredproperties in the hardened concrete. Mixture proportioning isdescribed in ACI 211.1, 211.2, and 211.3R.2.2Workability and consistencyWorkability of freshly mixed concrete determines the easeand homogeneity with which concrete can be mixed, placed,Fig. 1.1(a)Plea

26、sing appearance of concrete in churchconstruction.Fig. 1.1(b)Pleasing appearance of concrete in utilitybuilding construction.Fig. 1.1(c)Close-ups of surfaces resulting from goodconsolidation.309R-4 ACI COMMITTEE REPORTconsolidated, and finished. Workability is a function of therheological properties

27、 of the concrete.As shown in Fig. 2.1, workability may be divided intothree main aspects:1. Stability (resistance to bleeding and segregation);2. Ease of consolidation; and3. Consistency, affected by the viscosity and cohesion ofthe concrete and angle of internal friction.Workability is affected by

28、grading, particle shape, surfacetexture, proportions of aggregate and cement, use ofpozzolan or ground-granulated blast-furnace slag (GGBFS),chemical admixtures, air content, and water content of themixture. Consistency is the relative mobility or ability offreshly mixed concrete to flow. It also la

29、rgely determines theease with which concrete can be consolidated. Once thematerials and proportions are selected, the primary controlover workability is through variations in the water content orby adding a chemical admixture. The slump test (ASTM C143) is widely used to indicate consistency of mixt

30、ures usedin normal construction. The Vebe test (ASTM C 1170) isrecommended for stiffer mixtures. Values of slump,compacting factor, drop table spread, and Vebe time for theentire range of consistencies used in construction are givenin Table 2.1.Other measures of consistency, such as the Powersremold

31、ing test and the concrete rheometers recently developed,are available. These methods are infrequently used. Thevarious consistency tests have been discussed by Neville(1981), Vollick (1966), and Ferraris (1999).2.3Workability requirementsThe concrete should be sufficiently workable so that consoli-d

32、ation equipment, when properly used, will give adequateconsolidation. A high degree of ability to flow may be undesir-able because it may increase the cost of the mixture and reducethe quality of the hardened concrete. Where such a highdegree of ability to flow is the result of too much water in the

33、mixture, the mixture will generally be unstable and willprobably segregate during the consolidation process.In mixtures that are highly plastic to flowing (Table 2.1),small nominal maximum-size aggregate and high content offine aggregate are frequently used because the high degree ofability to flow

34、means less work in placing. Mixtures such asthese may have undesirable characteristics such as highshrinkage, cracking, and stickiness. At the other extreme, itis inadvisable to use mixtures that are too stiff for theintended conditions of consolidation. They will require greatconsolidation effort a

35、nd even then may not be adequatelyconsolidated. Direction, guidance, and trail mixtures areoften required to achieve the use of mixtures of lower slumpor fine aggregate content, or a larger nominal maximum-sizeaggregate, so as to give a more efficient use of the cement.Concrete containing certain ch

36、emical admixtures may beplaced in forms with less consolidation effort. Refer toreports of ACI Committee 212 for additional information.The use of pozzolans or GGBFS may also affect the consolida-tion effort required to properly consolidate concrete. Refer toACI 232.2R, 233R, and 234R for more infor

37、mationregarding these materials. The amount of consolidationeffort required with or without the use of chemical admix-tures and pozzolans or GGBFS should be determined by trialmixtures under field conditions.The workability of the mixture in the form determines theconsolidation requirements. This wo

38、rkability may be consid-erably less than at the mixer because of slump loss due to hightemperature, premature stiffening, delays, or other causes.CHAPTER 3METHODS OF CONSOLIDATIONThe consolidation method should be compatible with theconcrete mixture, placing conditions, form intricacy, andamount of

39、reinforcement. Many manual and mechanicalmethods are available.3.1Manual methodsPlastic, highly plastic, and flowing consistency (Table 2.1)mixtures may be consolidated by rodding. Spading is some-times used at formed surfacesa flat tool is repeatedly insertedand withdrawn adjacent to the form. Coar

40、se particles areshoved away from the form and movement of air voidstoward the top surface is facilitated, thereby reducing thenumber and size of bugholes in the formed concrete surface.Hand tamping may be used to consolidate stiff mixtures.The concrete is placed in thin layers, and each layer is car

41、efullyFig. 2.1Parameters of rheology of fresh concrete.Table 2.1Consistencies used in construction*Consistency descriptionSlump,in. (mm) Vebe time, sCompacting factor averageThaulow drop table revolutionsExtremely dry 32 to 18 112 to 56Very stiff 18 to 10 0.70 56 to 28Stiff0 to 1(0 to 25)10 to 5 0.7

42、5 28 to 14Stiff plastic1 to 3(25 to 75)5 to 3 0.85 14 to 7Plastic3 to 5(75 to 125)3 to 0*0.90 7Highly plastic5 to 7-1/2(125 to 190) Flowing7-1/2 plus(190 plus)0.95 *Test method is of limited value in this range.GUIDE FOR CONSOLIDATION OF CONCRETE 309R-5rammed or tamped. This is an effective consolid

43、ationmethod but is laborious and costly.The manual consolidation methods are generally onlyused on smaller nonstructural concrete placements and arelabor intensive.3.2Mechanical methodsThe most widely used consolidation method is vibration.Vibration may be either internal, external, or both.Power ta

44、mpers may be used to compact stiff concrete inprecast units. In addition to the ramming or tamping effect,there is a low-frequency vibration that aids in the consolidation.Mechanically operated tamping bars are suitable for consol-idating stiff mixtures for some precast products, includingconcrete m

45、asonry units.Equipment that applies static pressures to the top surface maybe used to consolidate thin concrete slabs of plastic or flowingconsistency. Concrete is literally squeezed into the mold, andentrapped air and part of the mixing water is forced out.Centrifugation (spinning) is used to conso

46、lidate concrete inconcrete pipe and other hollow sections and piles and poles.Many types of surface vibrators are available for slabconstruction, including vibrating screeds, vibratory rollerscreeds, plate and grid vibratory tampers, and vibratoryfinishing tools.Shock tables, sometimes called drop t

47、ables, are suitablefor consolidating low-slump concrete. The concrete isdeposited in thin lifts in sturdy molds. As the mold is filled,it is alternately raised a short distance and dropped on to asolid base. The impact causes the concrete to be rammed intoa dense mass. Frequencies are 150 to 250 dro

48、ps per min, andthe free fall is 1/8 to 1/2 in. (3 to 13 mm).Smooth-drum vibratory rollers are commonly used toconsolidate no-slump concrete mixtures.3.3Methods used in combinationUnder some conditions, a combination of two or moreconsolidation methods gives the best results.Internal and external vib

49、ration can often be combined toadvantage in precast work and occasionally in cast-in-placeconcrete. One scheme uses form vibrators for routineconsolidation and internal vibrators for spot use at critical,heavily reinforced sections prone to voids or poor bond withthe reinforcement. Conversely, in sections where the primaryconsolidation is by internal vibrators, form vibration mayalso be applied to achieve the desired surface appearance.Vibration may be simultaneously appl