1、Guide to Troubleshooting Concrete Mixture Issues as Influenced by Constitutive Materials, Jobsite Conditions, or Testing PracticesReported by ACI Committee 211ACI 211.8R-15First PrintingJune 2015ISBN: 978-1-942727-26-2Guide to Troubleshooting Concrete Mixture Issues as Influenced by Constitutive Mat
2、erials, Jobsite Conditions, or Testing PracticesCopyright 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, mechanical, electronic, film, or other distribution and storage media, without the
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11、 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 DriveFarmington Hills, MI 48331Phone: +1.248.848.3700Fax: +1.248.848.3701www.co
12、ncrete.orgThis guide describes adjustments that can be made to existing proportions for normal-density concrete with and without chemical admixtures, pozzolans, and slag. These adjustments are based on the performance of the concrete mixture as used in construction. The adjustments consider evaluati
13、on for placeability, consistency, strength, and durability. The procedures used in making these adjustments can be found in ACI 211.1. Adjustments to concrete mixture proportions or sources may require resubmittal to the design professional as detailed in ACI 301. This guide also provides informatio
14、n regarding jobsite conditions and testing practices that should be evaluated before adjustments are made to the mixture.Keywords: admixtures; aggregates; cementitious materials; durability; fine aggregates; fly ash; metakaolin; mixture proportioning; pozzolans; quality; silica fume; slag; slag ceme
15、nt; slump tests; water-cementitious material ratio.CONTENTSCHAPTER 1INTRODUCTION AND SCOPE, p. 21.1Introduction, p. 21.2Scope, p. 2Gary F. Knight, ChairTimothy S. Folks*, Vice ChairEd T. McGuire, SecretaryACI 211.8R-15Guide to Troubleshooting Concrete Mixture Issues as Influenced by Constitutive Mat
16、erials, Jobsite Conditions, or Testing PracticesReported by ACI Committee 211William L. Barringer*Katie J. BartojayMuhammed P. A. BasheerDavid A. BergJames C. Blankenship*Casimir J. BognackiMichael J. BoyleRamon L. CarrasquilloBryan R. CastlesTeck L. ChuaJames E. CookJohn F. Cook*David A. CrockerD.
17、Gene DanielKirk K. DeadrickDonald E. DixonDarrell F. ElliotDavid W. FowlerG. Terry Harris Sr*Richard D. HillDavid L. HollingsworthSaid IravaniTarif M. JaberRobert S. JenkinsJoe KelleyFrank A. KozeliskiDarmawan LudirdjaAllyn C. Luke*Kevin A. MacDonaldGary R. MassWarren E. McPherson JrJon I. MullarkyK
18、arthik H. OblaH. Celik OzyildirimJames S. PierceSteven A. RaganRoyce J. RhoadsJohn P. RiesG. Michael RobinsonJames M. Shilstone JrAva ShypulaWoodward L. Vogt*Michael A. Whisonantz*Members who contributed to this document.Chair of subcommittee.Subcommittee MembersYasar Yahia AbualrousDavid AnstineDal
19、e P. BentzZane BusslerLaurence M. ClodicCesar A. ConstantinoKenneth W. DayDimitri FeysPlinio Estuardo HerreraGene HightowerBerndt KanduthKenneth G. KazanisTyler LeyGuy LortieBlaine B. NyeBryan L. PettyNicholas J. PopoffDomenick Thomas RutturaLawrence L. SutterPaul D. TennisJames R. Van AckerHermanW.
20、 WentzPatrick J. HarrisonConsulting MemberJames N. LingscheitACI 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 a
21、nd limitations 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 there
22、from.Reference 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 211.8R-15 was adopted an
23、d published June 2015.Copyright 2015, 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 for sound or
24、 visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.1CHAPTER 2DEFINITIONS, p. 2CHAPTER 3REASONS FOR ADJUSTING MIXTURE PROPORTIONS, p. 2CHAPTER 4REFERENCES, p. 9Authored documents, p. 9CHAPTER 1INTROD
25、UCTION AND SCOPE1.1IntroductionThis document provides guidance for evaluating the performance of concrete mixture proportions and making adjustments during the construction process as well as iden-tifying construction or testing issues that can be wrongfully attributed to mixture proportioning. Adju
26、stments to the mixture proportions or materials in the production process may be needed to accommodate variations in materials, changes in climatic conditions, consistency or yield of the mixture, and deficiencies in the fresh or hardened concrete properties.1.2ScopeACI 211.1 provides methods for se
27、lecting proportions for concrete mixtures. Concrete may require adjustments to the mixture proportions throughout the course of the project due to the normal variation of the materials used in production, and the various conditions under which it will be delivered, placed, consolidated, and finished
28、. The concrete properties required in the hardened state may also require adjustments to the mixture proportions. It is important to note that no document can replace experience with the materials at hand when deciding what adjustments need to be made for a concrete mixture.CHAPTER 2DEFINITIONSACI p
29、rovides a comprehensive list of definitions through an online resource “ACI Concrete Terminology” at http:/www.concrete.org/store/productdetail.aspx?ItemID=CT13.CHAPTER 3REASONS FOR ADJUSTING MIXTURE PROPORTIONSThere are numerous reasons for adjusting the mixture proportions. The following are two e
30、xamples showing the need to adjust mixtures to alleviate an existing problem on a jobsite and also to correct the yield as a result of the change.3.1 Example No. 1A mixture design is being used in the field and the water required to produce a 5 in. (130 mm) slump is 10 lb/yd3(6 kg/m3) more than the
31、mixture design. To correct the water content, it will be added into the design. The original mixture proportions are as follows:a) Cement: 550 lb/yd3(326 kg/m3)b) No. 57 coarse aggregate: 1850 lb/yd3(1098 kg/m3)c) Fine aggregate: 1083 lb/yd3(643 kg/m3)d) Water: 268 lb/yd3(159 kg/m3)e) Air content: 5
32、 percentThe following is the information used in the original mixture design:a) Maximum water-cementitious material ratio (w/cm) required: 0.49b) Coarse aggregate factor: 0.7c) Specific gravity of cement: 3.15d) Specific gravity of coarse aggregate: 2.48e) Unit weight of coarse aggregate: 97.9 lb/ft
33、3(1568.2 kg/m3)f) Specific gravity of fine aggregate: 2.63The adjustment for the water demand will be based on the w/cm.The water will increase from 268 to 278 lb/yd3(159 to 165 kg/m3). To keep the w/cm the same, the cement will increase to 568 lb/yd3(337 kg/m3). The coarse aggregate will remain the
34、 same and the fine aggregate will be adjusted so the mixture will continue to yield 27 ft3/yd3(1 m3/m3).The adjusted mixture proportions will be as follows:a) Cement: 568 lb/yd3(337 kg/m3)b) No. 57 coarse aggregate: 1850 lb/yd3(1098 kg/m3)c) Fine aggregate: 1042 lb/yd3(618 kg/m3)d) Water: 278 lb/yd3
35、(165 kg/m3)e) Air content: 5 percent3.2 Example No. 2A mixture proportioned for a design strength of 4000 psi (28 MPa) at 28 days is only achieving an average of 2700 psi (19 MPa) at 7 days. Based on historical data of the relationship of 7 to 28-day strengths, the 28-day strength is predicted to be
36、 approximately 3800 psi (26 MPa). The mixture proportion will be adjusted to increase the strength by a targeted 500 psi (3.4 MPa). The original mixture proportions are as follows:a) Cement: 550 lb/yd3(326 kg/m3)b) No. 67 coarse aggregate: 1920 lb/yd3(1139 kg/m3)c) Fine aggregate: 1187 lb/yd3(704 kg
37、/m3)d) Water: 275 lb/yd3(163 kg/m3)e) Air content: 4 percentf) Water reducer: 17.0 oz./yd3(658 mL/m3)The following is the information used in the original mixture proportions:a) w/cm required: 0.52 maximumb) Coarse aggregate factor: 0.72c) Specific gravity of cement: 3.15d) Specific gravity of coars
38、e aggregate: 2.68e) Unit weight of coarse aggregate: 100.2 lb/ft3(1605.1 kg/m3)f) Specific gravity of fine aggregate: 2.63This concrete mixture, with an expected 28-day compres-sive strength of 3800 psi (26 MPa) and having 550 lb/yd3(326 kg/m3) of cement produces a cement efficiency at 28 days of 6.
39、9 psi/lb (0.080 MPa/kg/m3) (3800 psi/550 lb/yd3= 6.9 psi/lb/yd326 MPa/326 kg/m3). To adjust the mixture to yield an additional 500 psi (3.4 MPa) would take an addi-tional 72 lb/yd3(43 kg/m3) of cement (500 psi/6.9 psi/lb/yd3= 72 lb/yd33.4 MPa/0.080 MPa/kg/m3= 43 kg/m3).The new mixture will be as fol
40、lows:a) Cement: 622 lb/yd3(370 kg/m3)b) No. 67 coarse aggregate: 1920 lb/yd3(1139 kg/m3)c) Fine aggregate: 1126 lb/yd3(668 kg/m3)d) Water: 275 lb/yd3(163 kg/m3)e) Air content: 4 percentAmerican Concrete Institute Copyrighted Material www.concrete.org2 TROUBLESHOOTING CONCRETE ISSUES AS INFLUENCED BY
41、 MATERIALS, CONDITIONS, OR PRACTICES (ACI 211.8R-15)f) Water reducer: 19.25 oz/yd3(745 mL/m3)The weight of fine aggregate was reduced to compensate for the additional cement. Adding the additional cement lowers the w/cm to 0.44. The water reducer dose increased, as its use was based on the amount of
42、 cement in the mixture.These two examples demonstrate the consequence of one change in a concrete mixture to the final mixture proportions.3.3 Evaluation and adjustment of concrete mixturesThe evaluation of concrete mixture proportions during the course of a project will usually consist of observing
43、 changes in the properties of the concrete and addressing problems as they arise.Tables 3.3a through 3.3c indicate possible causes of typical production and application issues involving concrete. The tables do not attempt to address every possible situation that may occur; only the most common cause
44、s are covered. The situations in the table are also assumed to be single issues. Many times in practice, there are several issues occurring simultaneously. In most cases, issues with concrete arise in the initial construction phase. Issues such as low chemical resistance, however, may take some time
45、 to become evident and will likely not be observed during the initial construction phase. In some cases, building design, construction practice, and mixture design adjustments are all discussed. In these cases, there are numerous field changes outside of mixture design adjustment that can correct a
46、situation in the field. Often, correcting the field issue will alleviate the problem. If correcting the field issue does not solve the problem, then changes to mixture proportions should be considered.Table 3.3aFresh property issuesIssueArea of occurrence Possible cause Possible adjustments1. Air co
47、ntent: high/lowMixture A. Improper amount of admixture a) Increase or decrease amount.b) Ensure proper functioning of admixture dispenser.B. Admixture interaction a) Change dosage or type.b) Follow manufacturers recommendations.c) Change admixture dosage sequence.C. Insufficient slump Adjust slump;
48、refer to Issue 2, Slump: high/low.D. High-carbon fly ash. An increase in the loss on ignition (LOI) generally indicates an increase in carbon content. Carbon has a tendency to absorb air-entraining admixture. The high surface area of fly ash may also decrease air content at a fixed dose.a) Change fl
49、y ash or admixture dosage/type.E. Concrete temperature a) Correct temperature; refer to Issue 4, Temperature: high/low.b) Adjust dosage for temperatures.F. Cement or other cementitious materials. Slag cement fineness may change the air content of the mixture.Silica fume has a very high surface area. The high surface area may decrease the air content of the mixture.Metakaolin, like silica fume, has a high surface area and may decrease the air content of the mixture.An increase in soluble alkalis in the cement may increase air content.a) Change source of cementiti
