ACI 237R-2007 Self-Consolidating Concrete《自密实混凝土》.pdf

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1、ACI 237R-07 Self-Consolidating Concrete Reported by ACI Committee 237 Emerging Technology SeriesAmerican Concrete Institute Advancing concrete knowledge Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or

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9、iption, or reprint and may be obtained by contacting 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-

10、848-3701 www.concrete.org Self-Consolidating Concrete First Printing April 2007 ISBN 0-87031-244-8 ISBN-13: 978-0-87031-244-1ACI 237R-07 was adopted and published April 2007. Copyright 2007, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by a

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12、etors.237R-1 ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in 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 conten

13、t and recommendations and who will accept responsibility for the application of the material it contains. The 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 docu

14、ment shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. Self-Consolidating Concrete Reported by ACI Committee

15、237 Self-consolidating concrete (SCC) has been successfully used in many projects around the world and has made a major impact on concrete place- ment and construction economics. This report contains the current state of knowledge with respect to SCC. The information in this document is expected to

16、inform concrete producers, users, and specifiers of SCC of known practices and processes. Because SCC is a viable solution to various concrete placement problems, ASTM has established Subcommittee C09.47, Self- Consolidating Concrete, to develop standard test methods for SCC. Keywords: admixture; ag

17、gregate; air entrainment; bleeding; cement; consolidation; curing; placing; self-consolidating concrete; specification; viscosity, workability. CONTENTS Chapter 1Introduction, p. 237R-2 1.1Definition of self-consolidating concrete (SCC) 1.2Advantages 1.3Development history of SCC 1.4Selected case st

18、udies Chapter 2Fresh properties, p. 237R-9 2.1Terminology relative to SCC 2.2Performance requirements of SCC 2.3General 2.4Characteristics 2.5Target guidelines for fresh properties 2.6Quality control Chapter 3Hardened properties, p. 237R-12 3.1General 3.2Mechanical properties 3.3Long-term durability

19、 3.4Aesthetics Chapter 4Guide for selecting proportions for SCC, p. 237R-14 4.1General 4.2Performance requirements 4.3Materials 4.4Mixture proportioning procedure 4.5Examples of SCC mixture proportions Chapter 5Production, p. 237R-18 5.1General 5.2Production issues that influence fresh SCC propertie

20、s 5.3Performance targets Claude Bedard Chiara F. Ferraris Beatrix Kerkhoff Mohammed Sonebi Van K. Bui Sidney Freedman Gary F. Knight Richard Szecsy John F. Cook John V . Gruber Frank A. Nadeau Jody R. Wall Charles R. Cornman Venkatesh S. Iyer H. Celik Ozyildirim James A. Wamelink Kirk K. Deadrick Ph

21、ilippe Jost Qizhong Sheng * Associate member Mark Bury contributed to this report. Joseph A. Daczko Chair Kamal H. Khayat Secretary ACI 237R-07 Emerging Technology Series ACI encourages the development and appropriate use of new and emerging technologies through the publication of the Emerging Techn

22、ology Series. This series presents information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members. The presented information and recommendations, and their basis, may be less fully developed and teste

23、d than those for more mature technologies. This report identifies areas in which information is believed to be less fully developed, and describes research needs. The professional using this document should understand the limitations of this document and exercise judgment as to the appropriate appli

24、cation of this emerging technology.237R-2 ACI COMMITTEE REPORT 5.4Mock-up 5.5Employee training Chapter 6Transport, placement, and finishing, p. 237R-20 6.1General 6.2Transport 6.3Discharge of SCC for slabs or open-top molds for factory-type precast elements 6.4Forms, element characteristics, and rei

25、nforcement 6.5Placement techniques 6.6Finishing 6.7Curing Chapter 7SCC specification guidelines, p. 237R-24 7.1Concrete materials 7.2Execution Chapter 8Test methods, p. 237R-24 8.1Measuring SCC characteristics 8.2Slump flow 8.3Visual stability index 8.4T 50 8.5J-ring 8.6L-box 8.7Column segregation 8

26、.8Other tests Chapter 9References, p. 237R-27 9.1Referenced standards and reports 9.2Cited references CHAPTER 1INTRODUCTION 1.1Definition of self-consolidating concrete (SCC) Self-consolidating concrete (SCC) is highly flowable, nonsegregating concrete that can spread into place, fill the formwork,

27、and encapsulate the reinforcement without any mechanical consolidation. In general, SCC is concrete made with conventional concrete materials and, in some cases, with a viscosity-modifying admixture (VMA). SCC has also been described as self-compacting concrete, self-placing concrete, and self-level

28、ing concrete, which all are subsets of SCC. The nomenclature of this technology has been previously discussed (Szecsy 2002). In this report, conventional concrete is referred to as concrete that does not meet the definition of SCC. 1.2Advantages Properly proportioned and placed SCC can result in bot

29、h economic and technological benefits for the end user. The in- place cost savings, performance enhancements, or both, are the driving forces behind the use of SCC. Specifically, SCC can provide the following benefits: Reduce labor and equipment. No need for vibration to ensure proper consolidation.

30、 This also results in savings in equipment purchasing and equipment maintenance and operation; and Less need for screeding operations to ensure flat surfaces (self-leveling characteristic). Enable the casting of concrete that develops the desired mechanical properties independent of the skill of the

31、 vibrating crew; Accelerate construction through higher rate of casting or placing and shorter construction duration; Facilitate and expedite the filling of highly reinforced sections and complex formwork while ensuring good construction quality. This can ensure better produc- tivity, reduce the lab

32、or requirement and cost, or both; Enable more flexibility in spreading placing points during casting. This can reduce the need for frequent movement of transit trucks and the need to move the pump lines to place concrete (possible reduction in the number of pumps, pump operators, and so on). This gr

33、eater flexibility in scheduling construction activities and procuring the required resources results in both time and resource savings; Reduce noise on the job site (especially critical in urban areas and for sections requiring heavy vibration consolidation): Reduce the need of vibration for constru

34、ction typi- cally requiring the use of heavy consolidation (such as fiber-reinforced concrete and precast operations). In some cases, the use of noise-free or silent concrete can potentially extend construction hours in urban areas, enabling the scheduling of some construction activities during othe

35、rwise curfew periods to alleviate difficulties related to traffic conditions in urban areas; and Reduce insurance premiums. Precasting facilities generating considerable noise pollution are sometimes required to pay premiums to national insurance agencies responsible for eventual treatment of hearin

36、g-impaired workers. Insurance premium reductions can partially offset the additional material cost of SCC, making it attractive for precast operations. Decrease employee injuries by facilitating a safer working environment where strenuous and labor-intensive operations can reduce tripping hazards th

37、rough the removal of some electrical cords or air lines (Walraven 2003); Permit more flexibility for detailing reinforcing bars. Avoid the need to bundle reinforcement to facilitate placement and consolidation, and in some cases, enable the use of small and closely spaced reinforcing steel to contro

38、l cracking; Create smooth surfaces free of honeycombing and signs of bleeding and discoloration, obtained when using a well-proportioned SCC mixture, high-quality formwork with an adequate release agent, and sound placement practices (Chapter 6). Superior surface quality is critical in architectural

39、 concrete and cast-in-place and precast concrete for residential construction (walls); and Eliminate the need for materials, such as underlay- ments, that are used to level and prepare substrates for final flooring materials, such as carpeting and tile, whenever allowed by building regulations.SELF-

40、CONSOLIDATING CONCRETE 237R-3 1.3Development history of SCC The use of SCC has gained wide acceptance in Japan since the late 1980s. Initially, it was developed to ensure proper consolidation in applications where concrete durability and service life were of concern. SCC was later used to facilitate

41、 construction operations and reduce construction time and cost. For example, it has been used to cast sections with highly congested reinforcement and areas that present restricted access to placement and consolidation, including the construction of tunnel lining sections and the casting of hybrid c

42、oncrete-filled steel tubular columns. The following references provide various examples of the early use of SCC in civil engineering applications: Tanaka et al. (1993); Hayakawa et al. (1993, 1995); Miura et al. (1993); Okamura and Ozawa (1994); Takeuchi et al. (1994); Izumi et al. (1995); Fukute et

43、 al. (1995); Kitamura et al. (1996); and Ushijima et al. (1995). SCC has recently been used in concrete repair applications in Canada and Switzerland, including the repair of bridge abutments and pier caps, tunnel sections, parking garages, and retaining walls, where it ensured adequate filling of r

44、estricted areas and provided high surface quality (Jacobs and Hunkeler 2001; Khayat and Morin 2002). Since the early development of SCC in Japan, this new class of high-performance concrete has been employed in several countries in cast-in-place and precast applications (RILEM 2000; Khayat and Atcin

45、 1998; Skarendahl 2001; Walraven 2001; Ouchi 2001). The use of SCC in North America has grown dramatically, especially in the precast industry, where it has been used in regular production at precast plants in the United States since 2000. The majority of such concrete has been used to produce preca

46、st elements for parking garage structures and architectural panels. The estimated volume of SCC in the precast market in the United States was 177,000 yd 3 (135,000 m 3 ) in 2000; it increased to 2.3 million yd 3(1.8 million m 3 ) in 2003. *In 2002, 40% of precast manufacturers in the United States

47、had used SCC, and in some cases, new plants are currently being built around the idea of using SCC technology. *On the other hand, the use of SCC in the ready mixed concrete industry is still in its infancy in the United States, with estimated production in 2002 limited to 130,000 yd 3(100,000 m 3 )

48、 (Vachon and Daczko 2002). 1.4 Selected case studies Table 1.1 includes video clips of several SCC applications. For comparison purposes, there are clips showing a precast wall panel being produced with both conventional 8 in. (200 mm) slump concrete and SCC. Following Table 1.1 are five case studie

49、s that describe projects where SCC has been successfully used in North America. The mixture propor- tions included in these case studies are for example purposes only. For development of SCC mixture proportions, guide- lines are provided in Chapter 4. * Daczko, J., 2003, “Use of SCC in the Precast Industry in the United States.” (private communication) Table 1.1SCC project video clips* Project type Residential footings * Precast jail cell * Prestress double-tee * Wall panel * Wall panel * Slump flow, in