ACI ITG-8R-2010 Report on Performance-Based Requirements for Concrete.pdf

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1、ACI ITG-8R-10Reported by ACI Innovation Task Group 8Report on Performance-BasedRequirements for ConcreteReport on Performance-Based Requirements for ConcreteFirst PrintingDecember 2010ISBN 978-0-87031-405-6American Concrete InstituteAdvancing concrete knowledgeCopyright by the American Concrete Inst

2、itute, Farmington Hills, MI. All rights reserved. This materialmay not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or otherdistribution and storage media, without the written consent of ACI.The technical committees responsible for ACI committee reports an

3、d standards strive to avoid ambiguities,omissions, and errors in these documents. In spite of these efforts, the users of ACI documents occasionallyfind information or requirements that may be subject to more than one interpretation or may beincomplete or incorrect. Users who have suggestions for th

4、e improvement of ACI documents arerequested to contact ACI. Proper use of this document includes periodically checking for errata atwww.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 evaluate t

5、hesignificance and limitations of its content and recommendations and who will accept responsibility for theapplication of the material it contains. Individuals who use this publication in any way assume all risk andaccept total responsibility for the application and use of this information.All info

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9、uding but not limited to, United States Occupational Safety and Health Administration (OSHA) healthand safety standards.Order information: ACI documents are available in print, by download, on CD-ROM, through electronicsubscription, or reprint and may be obtained by contacting ACI.Most ACI standards

10、 and committee 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 ITG-8R-10 and was adopted and published December 2010.C

11、opyright 2010, 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 reproduc-tion or

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13、or theuse of individuals who are competent to evaluate thesignificance and limitations of its content and recommendationsand who will accept responsibility for the application of thematerial it contains. The American Concrete Institute disclaimsany and all responsibility for the stated principles. T

14、he Instituteshall not be 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 restated in mandatory language for inc

15、orporation bythe Architect/Engineer.Report on Performance-Based Requirementsfor ConcreteReported by ACI Innovation Task Group 8ACI ITG-8R-10This report discusses the differences between performance and prescrip-tive requirements for concrete, and provides information on developingperformance require

16、ments as an alternative to the current prescriptiverequirements in codes and specifications. Performance-based require-ments allow the contractor and concrete producer to be more innovativein concrete applications, providing an element for sustainability ofconcrete construction. The essential elemen

17、ts of a performance-basedrequirement are reviewed, which include the desired performance charac-teristics, sampling and testing procedures to verify these characteristics,and acceptance criteria. Because acceptance criteria are crucial elementsof effective performance specifications, factors to cons

18、ider in developingcriteria that distribute risks to the owner and members of the constructionteam are also discussed. Considerations for implementing performance-based requirements on a project are presented and development of perfor-mance-based requirements for durability emphasized. Alternative pe

19、rfor-mance-based requirements are proposed for the prescriptive durabilityrequirements in ACI 318.Keywords: acceptance criteria; bonus-penalty provisions; building code; dura-bility; in-place tests; performance specification; prescriptive specification;quality assurance (QA); responsibility; samplin

20、g; sustainability; test methods.CONTENTSChapter 1Introduction, p. 21.1Background1.2Objective and scope1.3Performance-based requirements1.4Comparison of performance-based and prescriptiverequirements1.5Sustainability and performance-based requirements1.6Responsibilities of involved parties1.7ACI code

21、s and specificationsChapter 2Definitions and acronyms, p. 122.1Definitions2.2AcronymsChapter 3Elements of performance-based requirements, p. 143.1Quality characteristics3.2Prequalification, identity, and surrogate testing3.3Test methods3.4Point of sampling and testing3.5Acceptance criteriaChapter 4D

22、evelopment of acceptance criteria,p. 204.1Introduction4.2Factors to considerVoting membersJohn A. Bickley*Anthony E. Fiorato Frank S. MalitsNicholas J. CarinoKenneth C. Hover*Ross S. MartinMark F. Chrzanowski*Consulting membersTerence C. Holland R. Doug Hooton*John W. Vaughan*Contributing author.Pri

23、ncipal author.Kenneth B. RearChair2 REPORT ON PERFORMANCE-BASED REQUIREMENTS FOR CONCRETE (ACI ITG-8R-10)American Concrete Institute Copyrighted Materialwww.concrete.org4.3Setting acceptability limits4.4Actions when acceptance criteria are not satisfiedChapter 5Implementation guidelines, p. 275.1 In

24、troduction5.2Pre-bid conference5.3Pre-award meeting5.4Preconstruction conferences5.5Bonus-penalty provisions5.6Challenges to successful implementationChapter 6Prescriptive durability requirements in ACI 318 and ACI 301 and performance-based alternatives, p. 346.1Review of existing prescriptive requi

25、rements fordurability6.2Proposed alternative performance specifications forconcreteChapter 7Summary and future actions, p. 407.1Summary7.2Path forwardChapter 8References, p. 428.1Referenced standards and reports8.2Cited referencesCHAPTER 1INTRODUCTION1.1Background1.1.1 Prescriptive and performance s

26、pecificationAsdefined by ASTM, a “specification” is an explicit set ofrequirements to be satisfied by a material, product, system,or service (ASTM 2010). In the concrete constructionindustry, the primary types of specifications are materialsspecifications and construction specifications. The formerp

27、rovide minimum requirements for composition and proper-ties, and the latter form part of the contract between ownerand contractor. Specifications can be of the “prescriptive” or“performance” type. A prescriptive specification forconcrete focuses on the properties of raw materials; mixtureproportions

28、; batching, mixing, and transport of freshconcrete; and a range of construction operations fromplacing to curing. Prescriptive specifications rely onobserved or implied relationships between the details speci-fied and the desired final, in-place, or end-product concreteperformance. Under a prescript

29、ive specification, the desiredend-product performance may or may not be described. Aperformance specification, however, defines requiredresults, the criteria to judge performance, and verificationmethods without requirements for how the results are to beobtained. An alternative name used by some age

30、ncies is end-result specification (ERS). The Federal Highway Adminis-tration (FHWA) has invested considerable resources topromote the use of performance-related specifications (PRS)in its projects (FHWA 1998). The PRS approach is intendedto ensure the completed product will perform as specified.Pres

31、criptive and performance specifications have been inexistence as long as code requirements and specifications forconcrete have existed. For example, in 1910, the NationalAssociation of Cement Users (NACU), the forerunner ofACI, adopted its “Standard Building Regulations for Rein-forced Concrete” (NA

32、CU 1910). These regulations providedalternatives for concrete strength:“Concrete composed of materials meeting the require-ments of these regulations, mixed in proportion of one partof cement and six parts of aggregate (fine and coarse), shalldevelop a compressive strength of 2000 pounds per squarei

33、nch in 28 days when tested as 8-in. diameter cylinders 16 in.long under laboratory conditions of manufacture andstorage, using the same consistency as is used in the field.When the proportion of cement is increased, using the bestquality of aggregates, an increase may be made in allworking stresses

34、proportional to the increase in compressivestrength at 28 days, as determined by actual tests, but thisincrease shall not exceed 25 per cent.”Thus, it is seen in this early document governing concreteconstruction, there were elements of prescriptive and perfor-mance requirements.In 1936, ACI adopted

35、 the “Building Regulations forReinforced Concrete (ACI 501-36T),” which serves as abasis for many provisions that are still in use today (Amer-ican Concrete Institute 1936). ACI 501-36T permitted aperformance-based alternative to the prescriptive water-cement ratio (w/c) requirements for different d

36、esignstrengths. Alternative mixture proportions were permitted byprequalifying a mixture on the basis of test data correlatingstrength to w/c. Four different w/c values had to be tested,and the w/c approved for production was that value corre-sponding to a compressive strength that was:20% greater t

37、han the design strength when designstrength was less than 2500 psi (17 MPa); and15% greater than the design strength when designstrength was 2500 psi (17 MPa) or above.These requirements are the forerunner of todays“required strength” based on standard deviation of historicaldata. Once the proposed

38、mixture was approved, no substitutionsin materials were permitted without additional tests.For durability, ACI 501-36T included that, “All concreteexposed to the weather shall have a minimum ultimate 28-daycompressive strength of not less than 3000 lb per sq. in.”According to ACI 501-36T, design pro

39、fessionals wereresponsible for on-site inspection of construction, includingmaintaining records of “the quality and quantity of concretematerials, the mixing and placing of the concrete, and theplacing of the reinforcing steel.”Today the responsibility for site verification of concreteproduction has

40、 shifted away from the licensed designprofessional toward the concrete producer. The licenseddesign professional, however, is still responsible for review orapproval of the submitted mixture ingredients and proportions.Other changes in the concrete industry since these earlycodes were written includ

41、e:Recognition that for many applications concrete strengthis not the only characteristic considered in developing anacceptable concrete mixture for a project;Portland cement is not the only cementitious material;REPORT ON PERFORMANCE-BASED REQUIREMENTS FOR CONCRETE (ACI ITG-8R-10) 3American Concrete

42、 Institute Copyrighted Materialwww.concrete.orgWater content and aggregate size are not the only factorsthat influence slump; andWater-cement ratio is not the only factor influencingpermeability.A variety of admixtures have emerged to impart characteristicsto a concrete mixture that are otherwise di

43、fficult or impossibleto attain by varying only the basic ingredients of cement,aggregate, and water. Chemical admixtures and supplementarycementitious materials (SCMs), such as pozzolans and slagcement, affect air content, air-void characteristics, workability,setting time, bleeding, rate of strengt

44、h gain, later-agestrength, and resistance to fluid penetration. In addition,combinations of the various cementitious materials andadmixtures may or may not be mutually compatible.It is difficult to write prescriptive specifications that makeuse of these developments while, at the same time, avoiding

45、their pitfalls. It is evident that evaluating concrete durabilityis more difficult than evaluating strength. The increasingdemand for improved concrete durability and growingcomplexity of concrete mixture design and proportioningadd importance to the debate of prescriptive versusperformance-based re

46、quirements.Interest in performance-based requirements is fueled bythe changes in practice that have evolved to enhanceconcrete durability and sustainability. For example, considerthe high-performance, low-permeability concretes requiredto ensure durable structures under severe exposures. Suchmixture

47、s often use portland cement along with one or moresupplementary cementitious material, may use one or moretype of admixture, may incorporate at least three sizes ofaggregate, and may have a corrosion inhibitor. Developingan acceptable mixture requires experience with specificmaterials, including rec

48、ognition that traditional relationships,such as those between workability and water content andthose between strength and w/c, are affected by a variety offactors, such as types and amounts of admixtures and SCM.In addition, the compatibility of admixtures with cementitiousmaterials should be invest

49、igated (Taylor et al. 2006). Toensure durability, the risk of cracking should be controlled,and the curing of such a mixture requires special attention toaccommodate rapid surface drying, rapid setting, and a highshrinkage potential.So, if questioned why performance-based requirementsshould be considered when prescriptive requirements havebeen the mainstay of the concrete industry, one answer mightbe that today we are demanding more of concrete, making itdifficult to take full advantage of the wide range of availableoptions under a strictly pres