ACI 309 1R-2008 Report on Behavior of Fresh Concrete During Vibration《振动时新拌混凝土的性能报告》.pdf

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1、ACI 309.1R-08Reported by ACI Committee 309Report on Behavior ofFresh Concrete During VibrationReport on Behavior of Fresh Concrete During VibrationFirst PrintingAugust 2008ISBN 978-0-87031-296-0American Concrete InstituteAdvancing concrete knowledgeCopyright by the American Concrete Institute, Farmi

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10、ee reports are gathered together in the annually revised ACI Manual ofConcrete Practice (MCP).American Concrete Institute38800 Country Club DriveFarmington Hills, MI 48331U.S.A.Phone: 248-848-3700Fax: 248-848-3701www.concrete.orgACI 309.1R-08 supersedes ACI 309.1R-93 and was adopted and published Au

11、gust 2008.Copyright 2008, 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, printed, written, or oral, or recording for sound or visual reprod

12、uctionor for use in any knowledge or retrieval system or device, unless permission in writingis obtained from the copyright proprietors.309.1R-1ACI Committee Reports, Guides, Manuals, StandardPractices, and Commentaries are intended for guidance inplanning, designing, executing, and inspecting const

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14、bility 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 of the contract documents, theyshall be res

15、tated in mandatory language for incorporation bythe Architect/Engineer.Report on Behavior of Fresh ConcreteDuring VibrationReported by ACI Committee 309ACI 309.1R-08This report covers the rheological and mechanical processes that takeplace during consolidation of fresh concrete. The first chapter pr

16、esents thehistorical developments relative to consolidating concrete. The secondchapter provides notations and definitions. The third chapter deals with therheological behavior of concrete during consolidation and the associatedmechanisms of dynamic compaction. The fourth chapter presents the prin-c

17、iples of vibratory motion occurring during vibration, vibratory methods,and experimental test results. Continuing research in the field of concretevibration, as evidenced by the extensive literature devoted to the subject, isaddressed.Keywords: admixtures; aggregates; aggregate shape and texture; ag

18、gregatesize; amplitude; compacting; consolidation; damping; energy; fresh concrete;hardening; history; mechanical impedance; mixture proportioning;reviews; rheological properties; stability; vibrations; vibrators (machinery).CONTENTSChapter 1Introduction and scope, p. 309.1R-2Chapter 2Notation and d

19、efinitions, p. 309.1R-42.1Notation2.2DefinitionsChapter 3Influence of rheology on consolidation of fresh concrete, p. 309.1R-53.1Rheology of fresh concrete3.2Rheology in practice3.3ConclusionsChapter 4Mechanisms of concrete vibration,p. 309.1R-64.1Introduction4.2Vibratory motion4.3Parameters of conc

20、rete vibration4.4Vibratory methodsChapter 5References, p. 309.1R-155.1Referenced standards and reports5.2Cited referencesTimothy P. Dolen*Glenn A. Heimbruch*Patrick F. OBrien, Jr. H. Celik OzyildirimChiara F. Ferraris*Gary R. Mass Larry D. Olson Steven A. RaganJerome H. Ford Richard E. Miller*Subcom

21、mittee members who prepared this report.Bradley K. ViolettaChair309.1R-2 ACI COMMITTEE REPORTCHAPTER 1INTRODUCTION AND SCOPEAt the turn of the twentieth century, concrete was generallyplaced as very dry mixtures, and was deposited in thin liftsand rammed into place by heavy tampers, which involvedex

22、tensive manual labor. Typical structures, such as foundations,retaining walls, and dams, contained little or no reinforcement.The concept of rammed concrete in thin lifts can be tracedback to the early Roman times, when the Pantheon was built.Many of these structures are still in service, proving th

23、at thistype of construction produced strong, durable concrete.In the early twentieth century, the common use of reinforcingsteel in concrete changed the consolidation requirements forconcrete. Concrete sections were greatly reduced in thickness.Constructors found that the dry mixtures could not beta

24、mped in the narrow forms filled with reinforcing steel and,consequently, water was added to facilitate placement intoforms without regard to effects on the mixture itself. Thechange from massive tamped concrete structures in the early1900s to relatively thin, reinforced concrete structures was amajo

25、r advance in engineering practice, but did not necessarilyresult in immediate improvements in concrete quality. Thedry, tamped concrete structures were somewhat less permeablethan the wet concrete placed into the first reinforced structures.Methods other than tamping were tried to consolidate stiffe

26、rconcrete. Compressed air was introduced into the freshconcrete through long jets. The practice of chuting concreteinto place resulted in excessively wet mixtures as the watercontent was increased (without increasing the cement) toallow the mixture to flow in chutes (Walter 1929). It becameapparent

27、that these wet mixtures did not produce goodconcrete (Engineering News Record 1923). The result waslower strength, durability failures, and increased dryingshrinkage and cracking. The poor durability of these firstreinforced concrete structures was of great concern to earlypractitioners. These mixtu

28、res would be described as“wetter,” though the slump test was yet to be standardized.The water-cement ratio concept, postulated by Abramsaround 1920, demonstrated that the quality of concretedropped rapidly as more water was added to the mixture(Abrams 1922a). In addition, the development of the trad

29、itionalslump test around 1922 gave the first measurable parameterfor indicating concrete consistency suitable for placementand an indication of quality (Abrams 1922b). Abramsdocumented an increase in compressive strength by compactinglow-consistency concrete with mechanical jigging.Difficulty consol

30、idating concrete in reinforced and massconcrete structures continued to be a problem until theintroduction of internal concrete vibrators in the early 1930s(McCarty 1933). The use of vibrators allowed stiffermixtures with less water to be placed, increasing bothconcrete strength and durability and d

31、ecreasing shrinkage. Inmass concrete dams, the introduction of the vibrator allowedthe placement of very stiff concrete in thick lifts with lowerwater contents and subsequently less cement, which reducedthermal cracking in dams. Consolidation by internal vibrationincreased the rate of placement per

32、day, and reduced internalflaws, such as cold joints.ACI Committee 609 (1936) described the benefits ofvibrators but was not able to explain the interaction betweena vibrator and fresh concrete. The frequencies of the early1900s vibrators were limited to 3000 to 5000 vibrations perminute (50 to 80 Hz

33、) because of design and maintenanceproblems. When it became apparent that higher frequencieswere possible and more effective in consolidating concrete,vibrator manufacturers made the necessary improvements.The following is an historical listing of notable research onthe consolidation of fresh concre

34、te. Observations were madeon the effect of air entrainment introduced in the late 1940son concrete consolidation. Air entrainment makes themixture more cohesive, and enhances particularly leanmixtures deficient in fines, as well as mass concrete.LHermite and Tournon (1948) reported fundamentalresear

35、ch on the mechanism of consolidation. They found thatfriction between the individual particles is the most importantfactor in preventing consolidation (densification), but friction ispractically eliminated when concrete is in a state of vibration.Meissner (1953) summarized research and reviewed stat

36、e-of-the-art equipment and its characteristics.ACI Committee 609 (1960) stated recommendations forvibrator characteristics applicable to different types ofconstruction and described field practices.Walz (1960) described the various types of vibratorsinternal, surface, form, and tableand their applic

37、ation. Itwas shown that the reduction in internal friction is primarilythe result of acceleration produced during vibration.Rebut (1962) discussed the theory of vibration, includingthe forces involved, the types of vibrators and their applicationto different classes of construction, and vibration-me

38、asuringdevices.Ersoy (1962) published the results of extensive laboratoryinvestigations on the consolidation effect of internal vibrators.Ersoy varied the concrete consistency, size and shape of form,and vibration parameters and concluded that the eccentricmoment, defined as the mass of the eccentri

39、c times its eccen-tricity (distance between the center of gravity and the center ofmotion), and frequency are important factors for determiningthe consolidation effectiveness of an internal vibrator.Kolek (1963) described vibration theories, formulas, andexperimental work aimed at a better understan

40、ding of theprocesses involved. He determined that consolidationoccurred in two stages: the first stage comprised the majorsubsidence or slumping of the concrete, and the second stageinvolved deaeration (removal of entrapped air).Kirkham (1963) developed empirical formulas to explainthe compaction of

41、 concrete slabs by the use of vibratingbeams or screeds on the surface. The force, amplitude ofvibration, and the vibration frequency were found to be themost important factors affecting the degree of consolidation.Murphy (1964) published a summary of post-World War IIBritish research, and compared

42、the findings and claims of thedifferent investigators. The studies made by Cusens (1955,1956), Kirkham (1963), and Kolek (1963) on the subject ofconsolidation were particularly noteworthy.Forssblad (1965a) reported on measurements of the radiusof action of internal vibrators operating at different f

43、requenciesBEHAVIOR OF FRESH CONCRETE DURING VIBRATION 309.1R-3and amplitudes, and with different vibration times andmixture consistencies. The radius of action was determinedfrom photographs of the concrete surface.Reading (1967) observed that for most ordinary mixtures,the stickiness imparted by ai

44、r entrainment makes it difficultto release entrapped air; consequently, more vibration maybe necessary for certain mixtures. Ritchie (1968) reviewedsuch concepts as workability and described such factors asstability, compactability, and mobility and the correspondingmethods of measurements.Shtaerman

45、 (1970) reported that ultra-high-frequencyvibration increases the hydration of the cement and improvesthe properties of concrete. High energy input and heatgeneration, and the small depth of penetration of the vibration,however, are drawbacks to this method.Wilde (1970) discussed the basic parameter

46、s involved inthe vibrator-concrete interaction and presented formulas forcomputing the radius and volume affected and the timerequired for consolidation.ACI Committee 309 (1982) published a report thatexplained the basic principles of consolidation and gaverecommendations for proportioning concrete

47、mixtures,equipment, and procedures for different types of construction,quality control, vibrator maintenance, and consolidation oftest specimens.A RILEM symposium at the University of Leeds in 1973included papers by Smalley and Ahmad (1973), Bache(1973), and Popovics (1973) that addressed rheologica

48、lproperties and consolidation of concrete.Cannon (1974) reported on the compaction of zero-slumpconcrete with a vibratory roller. Later, ACI Committee 207(1980) prepared a state-of-the-art report on this subject.Tattersall (1976) reported on the mobility of concrete bydetermining power requirements

49、for mixing at various speeds.Taylor (1976) published the results of extensive laboratorytests on the effect of different parameters on the effective-ness of internal vibrators. Gamma ray scanning was used todetermine the density of the concrete and, hence, the radiusof action of the vibrators. Acceleration and amplitude werefound to be the most important parameters.Alexander (1977) reported basic research on themechanics of motion of fresh concrete. It was found that theresponse of concrete to vibration under low applied forcescan be expressed in terms of stiffness, dam