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1、ACI 309.1R-08 Reported by ACI Committee 309 Report on Behavior of Fresh Concrete During Vibration Report on Behavior of Fresh Concrete During Vibration First Printing August 2008 ISBN 978-0-87031-296-0 American Concrete Institute Advancing concrete knowledge Copyright by the American Concrete Instit
2、ute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of ACI. The technical committees responsible for ACI committee reports a
3、nd standards strive to avoid ambiguities, omissions, and errors in these documents. In spite of these efforts, the users of ACI documents occasionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions fo
4、r the improvement of ACI documents are requested to contact ACI. Proper use of this document includes periodically checking for errata at www.concrete.org/committees/errata.asp for the most up-to-date revisions. ACI committee documents are intended for the use of individuals who are competent to eva
5、luate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. Individuals who use this publication in any way assume all risk and accept total responsibility for the application and use of this informatio
6、n. All information in this publication is provided “as is” without warranty of any kind, either express or implied, including but not limited to, the implied warranties of merchantability, fitness for a particular purpose or non-infringement. ACI and its members disclaim liability for damages of any
7、 kind, including any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost profits, which may result from the use of this publication. It is the responsibility of the user of this document to establish health and safety practices appropriate to
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9、and regulations, including but not limited to, United States Occupational Safety and Health Administration (OSHA) health and safety standards. Order information: ACI documents are available in print, by download, on CD-ROM, through electronic subscription, or reprint and may be obtained by contactin
10、g ACI. Most ACI standards and committee reports are gathered together in the annually revised ACI Manual of Concrete Practice (MCP). American Concrete Institute 38800 Country Club Drive Farmington Hills, MI 48331 U.S.A. Phone:248-848-3700 Fax:248-848-3701 www.concrete.org ACI 309.1R-08 supersedes AC
11、I 309.1R-93 and was adopted and published August 2008. Copyright 2008, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by electronic or mechanical device, printed, written,
12、or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. 309.1R-1 ACI Committee Reports, Guides, Manuals, Standard Practices, and Commentaries are intended for guidance i
13、n planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. Th
14、e American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute 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/E
15、ngineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. Report on Behavior of Fresh Concrete During Vibration Reported by ACI Committee 309 ACI 309.1R-08 This report covers the rheological and mechanical processes that
16、 take place during consolidation of fresh concrete. The first chapter presents the historical developments relative to consolidating concrete. The second chapter provides notations and definitions. The third chapter deals with the rheological behavior of concrete during consolidation and the associa
17、ted mechanisms of dynamic compaction. The fourth chapter presents the prin- ciples of vibratory motion occurring during vibration, vibratory methods, and experimental test results. Continuing research in the field of concrete vibration, as evidenced by the extensive literature devoted to the subject
18、, is addressed. Keywords: admixtures; aggregates; aggregate shape and texture; aggregate size; amplitude; compacting; consolidation; damping; energy; fresh concrete; hardening; history; mechanical impedance; mixture proportioning; reviews; rheological properties; stability; vibrations; vibrators (ma
19、chinery). CONTENTS Chapter 1Introduction and scope, p. 309.1R-2 Chapter 2Notation and definitions, p. 309.1R-4 2.1Notation 2.2Definitions Chapter 3Influence of rheology on consolidation of fresh concrete, p. 309.1R-5 3.1Rheology of fresh concrete 3.2Rheology in practice 3.3Conclusions Chapter 4Mecha
20、nisms of concrete vibration, p. 309.1R-6 4.1Introduction 4.2Vibratory motion 4.3Parameters of concrete vibration 4.4Vibratory methods Chapter 5References, p. 309.1R-15 5.1Referenced standards and reports 5.2Cited references Timothy P. Dolen*Glenn A. Heimbruch* Patrick F. OBrien, Jr.H. Celik Ozyildir
21、im Chiara F. Ferraris* Gary R. MassLarry D. OlsonSteven A. Ragan Jerome H. FordRichard E. Miller *Subcommittee members who prepared this report. Bradley K. Violetta Chair 309.1R-2ACI COMMITTEE REPORT CHAPTER 1INTRODUCTION AND SCOPE At the turn of the twentieth century, concrete was generally placed
22、as very dry mixtures, and was deposited in thin lifts and rammed into place by heavy tampers, which involved extensive 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 traced ba
23、ck to the early Roman times, when the Pantheon was built. Many of these structures are still in service, proving that this type of construction produced strong, durable concrete. In the early twentieth century, the common use of reinforcing steel in concrete changed the consolidation requirements fo
24、r concrete. Concrete sections were greatly reduced in thickness. Constructors found that the dry mixtures could not be tamped in the narrow forms filled with reinforcing steel and, consequently, water was added to facilitate placement into forms without regard to effects on the mixture itself. The c
25、hange from massive tamped concrete structures in the early 1900s to relatively thin, reinforced concrete structures was a major advance in engineering practice, but did not necessarily result in immediate improvements in concrete quality. The dry, tamped concrete structures were somewhat less permea
26、ble than the wet concrete placed into the first reinforced structures. Methods other than tamping were tried to consolidate stiffer concrete. Compressed air was introduced into the fresh concrete through long jets. The practice of chuting concrete into place resulted in excessively wet mixtures as t
27、he water content was increased (without increasing the cement) to allow the mixture to flow in chutes (Walter 1929). It became apparent that these wet mixtures did not produce good concrete (Engineering News Record 1923). The result was lower strength, durability failures, and increased drying shrin
28、kage and cracking. The poor durability of these first reinforced concrete structures was of great concern to early practitioners. These mixtures would be described as “wetter,” though the slump test was yet to be standardized. The water-cement ratio concept, postulated by Abrams around 1920, demonst
29、rated that the quality of concrete dropped rapidly as more water was added to the mixture (Abrams 1922a). In addition, the development of the traditional slump test around 1922 gave the first measurable parameter for indicating concrete consistency suitable for placement and an indication of quality
30、 (Abrams 1922b). Abrams documented an increase in compressive strength by compacting low-consistency concrete with mechanical jigging. Difficulty consolidating concrete in reinforced and mass concrete structures continued to be a problem until the introduction of internal concrete vibrators in the e
31、arly 1930s (McCarty 1933). The use of vibrators allowed stiffer mixtures with less water to be placed, increasing both concrete strength and durability and decreasing shrinkage. In mass concrete dams, the introduction of the vibrator allowed the placement of very stiff concrete in thick lifts with l
32、ower water contents and subsequently less cement, which reduced thermal cracking in dams. Consolidation by internal vibration increased the rate of placement per day, and reduced internal flaws, such as cold joints. ACI Committee 609 (1936) described the benefits of vibrators but was not able to exp
33、lain the interaction between a vibrator and fresh concrete. The frequencies of the early 1900s vibrators were limited to 3000 to 5000 vibrations per minute (50 to 80 Hz) because of design and maintenance problems. When it became apparent that higher frequencies were possible and more effective in co
34、nsolidating concrete, vibrator manufacturers made the necessary improvements. The following is an historical listing of notable research on the consolidation of fresh concrete. Observations were made on the effect of air entrainment introduced in the late 1940s on concrete consolidation. Air entrain
35、ment makes the mixture more cohesive, and enhances particularly lean mixtures deficient in fines, as well as mass concrete. LHermite and Tournon (1948) reported fundamental research on the mechanism of consolidation. They found that friction between the individual particles is the most important fac
36、tor in preventing consolidation (densification), but friction is practically eliminated when concrete is in a state of vibration. Meissner (1953) summarized research and reviewed state- of-the-art equipment and its characteristics. ACI Committee 609 (1960) stated recommendations for vibrator charact
37、eristics applicable to different types of construction and described field practices. Walz (1960) described the various types of vibrators internal, surface, form, and tableand their application. It was shown that the reduction in internal friction is primarily the result of acceleration produced du
38、ring vibration. Rebut (1962) discussed the theory of vibration, including the forces involved, the types of vibrators and their application to different classes of construction, and vibration-measuring devices. Ersoy (1962) published the results of extensive laboratory investigations on the consolid
39、ation effect of internal vibrators. Ersoy varied the concrete consistency, size and shape of form, and vibration parameters and concluded that the eccentric moment, defined as the mass of the eccentric times its eccen- tricity (distance between the center of gravity and the center of motion), and fr
40、equency are important factors for determining the consolidation effectiveness of an internal vibrator. Kolek (1963) described vibration theories, formulas, and experimental work aimed at a better understanding of the processes involved. He determined that consolidation occurred in two stages: the fi
41、rst stage comprised the major subsidence or slumping of the concrete, and the second stage involved deaeration (removal of entrapped air). Kirkham (1963) developed empirical formulas to explain the compaction of concrete slabs by the use of vibrating beams or screeds on the surface. The force, ampli
42、tude of vibration, and the vibration frequency were found to be the most important factors affecting the degree of consolidation. Murphy (1964) published a summary of post-World War II British research, and compared the findings and claims of the different investigators. The studies made by Cusens (
43、1955, 1956), Kirkham (1963), and Kolek (1963) on the subject of consolidation were particularly noteworthy. Forssblad (1965a) reported on measurements of the radius of action of internal vibrators operating at different frequencies BEHAVIOR OF FRESH CONCRETE DURING VIBRATION309.1R-3 and amplitudes,
44、and with different vibration times and mixture consistencies. The radius of action was determined from photographs of the concrete surface. Reading (1967) observed that for most ordinary mixtures, the stickiness imparted by air entrainment makes it difficult to release entrapped air; consequently, m
45、ore vibration may be necessary for certain mixtures. Ritchie (1968) reviewed such concepts as workability and described such factors as stability, compactability, and mobility and the corresponding methods of measurements. Shtaerman (1970) reported that ultra-high-frequency vibration increases the h
46、ydration of the cement and improves the properties of concrete. High energy input and heat generation, and the small depth of penetration of the vibration, however, are drawbacks to this method. Wilde (1970) discussed the basic parameters involved in the vibrator-concrete interaction and presented f
47、ormulas for computing the radius and volume affected and the time required for consolidation. ACI Committee 309 (1982) published a report that explained the basic principles of consolidation and gave recommendations for proportioning concrete mixtures, equipment, and procedures for different types o
48、f construction, quality control, vibrator maintenance, and consolidation of test specimens. A RILEM symposium at the University of Leeds in 1973 included papers by Smalley and Ahmad (1973), Bache (1973), and Popovics (1973) that addressed rheological properties and consolidation of concrete. Cannon
49、(1974) reported on the compaction of zero-slump concrete 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 by determining power requirements for mixing at various speeds. Taylor (1976) published the results of extensive laboratory tests on the effect of different parameters on the effective- ness of internal vibrators. Gamma ray scanning was used to determine the density of the concrete and, hence, the radius of action of the vibrators. Acceleration and amp
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