ACI 506R-2016 Guide to Shotcrete.pdf

1、Guide to ShotcreteReported by ACI Committee 506ACI 506R-16First PrintingJune 2016ISBN: 978-1-942727-95-8Guide to ShotcreteCopyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanic

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3、occasionally find information or requirements that may be subject to more than one interpretation or may be incomplete or incorrect. Users who have suggestions for the improvement of ACI documents are requested to contact ACI via the errata website at http:/concrete.org/Publications/DocumentErrata.a

4、spx. Proper use of this document includes periodically checking for errata for the most up-to-date revisions.ACI committee documents are intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsib

5、ility 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 information.All information in this publication is provided “as is” without warranty of any kind, either express

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7、n, 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 the specific circumstances involved with its use. ACI does not make any representations with regard to hea

8、lth and safety issues and the use of this document. The user must determine the applicability of all regulatory limitations before applying the document and must comply with all applicable laws and regulations, including but not limited to, United States Occupational Safety and Health Administration

9、 (OSHA) health and safety standards.Participation by governmental representatives in the work of the American Concrete Institute and in the development of Institute standards does not constitute governmental endorsement of ACI or the standards that it develops.Order information: ACI documents are av

10、ailable in print, by download, on CD-ROM, through electronic subscription, 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 Institute38800 Country Club Drive

11、Farmington Hills, MI 48331Phone: +1.248.848.3700Fax: +1.248.848.3701www.concrete.orgThis guide is a companion document to ACI 506.2, “Specification for Shotcrete,” and provides information on materials and prop-erties of both dry-mix and wet-mix shotcrete. Most facets of the shotcrete process are co

12、vered, including application procedures, equipment requirements, and responsibilities of the shotcrete crew. Other aspects, such as preconstruction trials, craftsman qualifica-tion tests, materials tests, finished shotcrete acceptance tests, and equipment, are also discussed.Keywords: dry-mix shotcr

13、ete; mixture proportion; placing; quality control; shotcrete; wet-mix shotcrete.CONTENTSPREFACE, p. 2Introduction, p. 2History, p. 2Applications, p. 2New developments, p. 2Research and development, p. 3PART 1GENERAL, p. 31.1Scope, p. 31.2Definitions, p. 41.3References: See Part 7References, p. 51.4S

14、ubmittals, p. 51.5Preconstruction testing by contractor, p. 51.6Testing during construction: quality assurance and quality control, p. 61.7Delivery, storage, and handling, p. 9PART 2PRODUCTS, p. 92.1Materials, p. 92.2Packaged shotcrete materials, p. 132.3Fiber-reinforced shotcrete, p. 132.4Shotcrete

15、 properties, p. 132.5Proportioning, p. 162.6Batching and mixing, p. 18PART 3EXECUTION, p. 203.1Surface preparation, p. 203.2Joints, p. 233.3Alignment control, p. 243.4Application, p. 253.5Finishing, p. 353.6Curing, p. 373.7Protection, p. 38Marc Jolin, Chair James A. Ragland, SecretaryACI 506R-16Guid

16、e to ShotcreteReported by ACI Committee 506Voting membersJon B. ArdahlLars F. Balck Jr.*Michael BallouLouis-Samuel BolducChris D. BreedsWern-Ping Nick ChenScott R. CummingWilliam T. Drakeley Jr.Charles S. HanskatWarren L. HarrisonThomas HenningsLarry G. LepperMark R. LukkarilaJeffrey L. NovakRyan E.

17、 PooleJohn H. PyeRaymond C. Schallom IIIPhilip T. SeabrookW. L. Snow Sr.Jason P. SouthLawrence J. TottenMarcus H. von der HofenCurtis WhitePeter T. YenGeorge YoggyLihe ZhangChris M. Zynda*Subcommittee Chair who produced this guide.Consulting membersJean-Francois DufourMerlyn IsaakRichard A. KadenDud

18、ley R. MorganH. Celik OzyildirimHarvey W. ParkerACI Committee Reports, Guides, 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 limitation

19、s of its content 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.Referenc

20、e to this document 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.ACI 506R-16 supersedes ACI 506R-05 and wa

21、s adopted and published June 2016.Copyright 2016, 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, or oral, or recording

22、for sound or visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.13.8Tolerances, p. 383.9Repair, p. 393.10Acceptance, p. 39PART 4EQUIPMENT, p. 404.1Introduction, p. 404.2Dry-mix equipment, p. 404.3Wet

23、-mix equipment, p. 414.4Air requirements, p. 424.5Mixing equipment, p. 434.6Hoses, p. 434.7Nozzles, p. 444.8Auxiliary equipment, p. 454.9Plant layout and operation, p. 474.10Other uses of shotcrete equipment, p. 47PART 5CREW ORGANIZATION, p. 485.1Introduction, p. 485.2Composition and crew duties, p.

24、 485.3Crew qualifications, p. 495.4Communication, p. 49PART 6SUSTAINABILITY, p. 496.1Shotcrete sustainability, p. 496.2nullFormwork reduction or elimination, p. 506.3Construction efficiency, p. 506.4Repair and rehabilitation, p. 506.5Creativity and efficiency of shotcrete sections, p. 506.6Summary,

25、p. 50PART 7REFERENCES, p. 50Authored references, p. 52PREFACEThis guide, based on many years of practice and expe-rience, covers aspects of shotcrete construction, including materials, equipment, crew organization, preliminary prep-aration, proportioning, shotcrete placement, and quality assurance/q

26、uality control. Procedures vary from one region to another, however, and adjustments for a particular project are often necessary.New construction, repair, linings, coatings, refractories, underground support, and other special applications are also discussed. No attempt is made to provide guideline

27、s for the design of shotcrete installations. The purpose of this docu-ment is to serve as a guide to engineers and contractors and as commentary to ACI 506.2, “Specification for Shotcrete.”IntroductionShotcrete is an important and widely used construction tech-nique. Because of continuing research a

28、nd development in materials, equipment, and construction procedures, this guide is revised periodically to reflect current industry practice.HistoryIn 1910, a double-chambered cement gun (dry-mix), based on a design developed by Carl Akeley, was introduced to the construction industry. The sand-ceme

29、nt product produced by this device was given the proprietary name “gunite”. In the ensuing years, trademarks such as Guncrete, Pneucrete, Blastcrete, Blocrete, Jetcrete, and the terms “pneumatically applied mortar or concrete” and “sprayed concrete” were introduced to describe similar processes. Bet

30、ween 1930 and 1950, gunite/shotcrete gained wide acceptance around the world because, at that time, gunite/shotcrete strength was superior to concrete and permitted the contractor to easily transport a sand cement mixture over long distances to difficult-to-reach areas. In the early 1930s, The Ameri

31、can Railway Engineering Association introduced the term “shot-crete” to describe the gunite process. In 1951, the American Concrete Institute adopted the term “shotcrete” to describe the dry-mix process. It is now also applied to the wet-mix process and has gained widespread acceptance in the United

32、 States and around the world.In the 1950s, wet-mix shotcrete, the use of coarse aggre-gate in both processes, the rotary gun for dry-mix shotcrete, and more efficient concrete pumps for wet-mix shotcrete were introduced. Many improvements were made to wet-mix equipment, primarily concrete pumps and

33、materials, in the 1970s and 1980s. These improvements allowed pumping low-slump shotcrete mixtures longer distances at greater volumes. These innovations enhanced the utility, flexibility, and general effectiveness of the process. More recently, there have been advances and developments in admixture

34、s and robotic placement of shotcrete, broadening the range of shotcrete applications.Centrifugally applied concrete and low-pressure, low-velocity wet-process mortar and concrete are not considered shotcrete and not covered in this guide because they do not comply with the current definition of shot

35、crete; they do not achieve sufficient consolidation to be considered shotcrete (“Application and Use of Shotcrete” 1981).ApplicationsShotcrete can be used instead of conventional concrete in many instances, the choice being based on convenience and cost. Shotcrete offers advantages over conventional

36、 concrete in a variety of new construction and repair work.Reinforcement details may complicate the use of shot-crete, but shotcrete is particularly cost effective where formwork is impractical or where forms can be reduced or eliminated; access to the work area is difficult; thin layers, variable t

37、hickness, or both, are required; or normal casting techniques cannot be employed. The excellent bond of shot-crete to a number of materials is sometimes an important design consideration.New developmentsThe future of shotcrete is limited only by the speed of development of new materials, equipment,

38、and techniques. A prime example of major expansion in the use of shotcrete is in early and final lining ground support in tunnels and mines. Improvements in prepackaged products; acceler-ating and setting-control admixtures; the use of fibers; and specially designed equipment, including robotic and

39、remote control shotcrete devices, have spurred the development of American Concrete Institute Copyrighted Material www.concrete.org2 GUIDE TO SHOTCRETE (ACI 506R-16)ground support techniques competitive with conventional steel rib and lagging supports (ACI 506.5R; ACI 506.1R).Research and developmen

40、tThe ability of the shotcrete process to handle and place materials that have almost instantaneous hardening capa-bilities should result in expanding applications in the future. Areas of future research and development include rational shotcrete structural design, nozzle design, in-place testing tec

41、hniques, materials, equipment mechanization, substrate evaluation, process automation, surface finish, and evalua-tion of reinforcement encasement. The use of shotcrete in the construction industry will increase as more aspects of the shotcrete method from design to installation are developed.PART 1

42、GENERAL1.1Scope1.1.1 Work specified (shotcreting processes)The work should be classified as either structural or nonstructural. Shotcrete having a specified compressive strength of 4000 psi (28 MPa) or greater is considered structural shotcrete. Shot-creting can be applied by one of two processes: w

43、et-mix or dry-mix. Shotcrete is further described according to the size of aggregate used (coarse or fine). Refer to Table 1.1.1 for fine-aggregate grading (No. 1) and coarse-aggregate grading (No. 2).1.1.1.1 Dry-mix processThe dry-mix process consists of five steps and are as follows:1. All dry ing

44、redients, except water, are thoroughly mixed. Dry ingredients are predampened to contain approximately 6 percent moisture.2. The cementitious aggregate mixture is fed into a special mechanical feeder or gun called the delivery equipment.3. The mixture is usually introduced into the delivery hose by

45、a metering device such as a feed wheel, rotor, or feed bowl. Some equipment uses air pressure alone (orifice feed) to deliver the material into the hoses.4. The material is carried by compressed air through the delivery hose to a nozzle body. The nozzle body is fitted inside with a water ring throug

46、h which water is intro-duced under pressure and thoroughly mixes with the other ingredients.5. The material is jetted from the nozzle at high velocity onto the surface to be shotcreted.1.1.1.2 Wet-mix processThe wet-mix process consists of five steps and are as follows:1. All ingredients, including

47、mixing water, are thoroughly mixed.2. The shotcrete mixture is introduced into the chamber of the delivery equipment.3. The mixture is metered into the delivery hose and moved by positive displacement.4. Compressed air is injected at the nozzle to increase velocity and improve the shooting pattern.5

48、. The concrete is jetted from the nozzle at high velocity onto the surface to be shotcreted.1.1.1.3 Comparison of processesEither process can produce shotcrete suitable for normal construction require-ments. Differences in capital and maintenance cost of equip-ment, operational features, suitability

49、 of available aggregate, and placement characteristics, however, may make one or the other more attractive for a particular application. Table 1.1.1.3 gives differences in operational features and other properties that merit consideration.1.1.1.4 Coarse aggregate shotcreteAlthough in its early years, shotcreting was performed with fine-aggregate-based materials (mortar), most of todays applications (both wet-mix and dry-mix) include larger maximum-size aggre-gate (refer to Table 1.1.1 Grading No. 2).There are six reasons for ad