ACI 222 3R-2011 Guide to Design and Construction Practices to Mitigate Corrosion of Reinforcement in Concrete Structures.pdf

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1、ACI 222.3R-11Reported by ACI Committee 222Guide to Design and ConstructionPractices to Mitigate Corrosion ofReinforcement in Concrete StructuresGuide to Design and Construction Practices to Mitigate Corrosionof Reinforcement in Concrete StructuresFirst PrintingApril 2011ISBN 978-0-87031-422-3America

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10、on CD-ROM, through electronicsubscription, or reprint and may be obtained by contacting ACI.Most ACI standards 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.P

11、hone: 248-848-3700Fax: 248-848-3701www.concrete.orgACI 222.3R-11 supersedes 222.3R-03 and was adopted and published April 2011.Copyright 2011, 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 ph

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13、mmentariesare intended for guidance in planning, designing, executing,and inspecting construction. This document is intended for theuse of individuals who are competent to evaluate thesignificance and limitations of its content and recommendationsand who will accept responsibility for the applicatio

14、n of thematerial it contains. The American Concrete Institute disclaimsany and all responsibility for the stated principles. The 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 ar

15、e desired by theArchitect/Engineer to be a part of the contract documents, theyshall be restated in mandatory language for incorporation bythe Architect/Engineer.Guide to Design and Construction Practicesto Mitigate Corrosion of Reinforcementin Concrete StructuresReported by ACI Committee 222ACI 222

16、.3R-11Corrosion of metals in concrete is a significant problem throughout theworld. In many instances, corrosion can be avoided if proper attention isgiven to detailing, concrete materials and mixture proportions, andconstruction practices. This guide contains information on aspects of eachof these.

17、 In addition, the guide contains recommendations for protectingin-service structures exposed to corrosive conditions. The guide is intendedfor designers, materials suppliers, contractors, and all others engaged inconcrete construction.Keywords: admixtures; aggregates; aluminum; cathodic protection;c

18、ement; chlorides; consolidation; corrosion; curing; epoxy coating; high-range water-reducing admixtures; mixing; mixture proportioning; permeability;reinforcing steel; water-cementitious material ratio.CONTENTSForeword, p. 2Chapter 1Introduction, p. 2Chapter 2Design considerations, p. 22.1Structural

19、 types and corrosion2.2Environment and corrosion2.3Cracking and corrosion2.4Structural details and corrosionChapter 3Impact of mixture proportioning, concreting materials, and type of embeddedmetal, p. 73.1Influence of mixture proportioning on corrosionof reinforcing steel3.2Influence of selection o

20、f cement, aggregates, water,and admixtures on corrosion of reinforcing steel3.3Uncoated reinforcing steel3.4Epoxy-coated reinforcing steel3.5Embedded metals other than reinforcing steelAntonio J. Aldykiewicz Jr. David P. Gustafson Charles K. Nmai Paul G. TourneyMichael C. Brown Carolyn M. Hansson Ra

21、ndall W. Poston Yash Paul VirmaniDavid Darwin William G. Hime Ruben M. Salas Jeffrey S. WestMarwan A. Daye Brian B. Hope Arpad Savoly Richard E. WeyersStephen D. Disch Tracy D. Marcotte Andrea J. Schokker David W. WhitmoreHamid Farzam David B. McDonald Morris Schupack John B. WojakowskiPer Fidjestl

22、Theodore L. Neff Khaled A. SoudkiMohammad S. KhanChairDavid TrejoSecretary2 PRACTICES TO MITIGATE CORROSION OF REINFORCEMENT IN CONCRETE STRUCTURES (ACI 222.3R-11)American Concrete Institute Copyrighted Materialwww.concrete.orgChapter 4Construction practices, p. 134.1Mixing and transporting concrete

23、4.2Placement of concrete and steel4.3Consolidation4.4Influence of curing on corrosion of reinforcing steelChapter 5Evaluation and protection of in-service structures, p. 155.1Types of structures susceptible to corrosion-relateddeterioration5.2Evaluation of in-service structures5.3Barrier systems for

24、 concrete5.4Admixtures that extend life of reinforced concretestructures exposed to chloride environments5.5Cathodic protection5.6Electrochemical chloride extractionChapter 6References, p. 206.1Referenced standards and reports6.2Cited referencesFOREWORDThis guide represents a compendium of technolog

25、y tocombat the problems of corrosion and is arranged into fourmajor chapters. Chapter 2 discusses design considerationspertinent to corrosion, including environmental factors,performance of structural types, and the influence of structuraldetails. Chapter 3 addresses the effects of concrete material

26、sand mixture proportions on susceptibility to corrosion,including cements, aggregates, water, reinforcing steels,admixtures, and other embedded materials. Chapter 4 examinescorrosion as it is influenced by the changes that concreteundergoes as it is mixed, transported, placed, consolidated,and cured

27、. Chapter 5 describes several procedures availablefor protecting in-place structures.This guide will aid in the design and construction ofcorrosion-resistant reinforced concrete structures and assistthose involved in ensuring that reinforced concrete continuesto function as a reliable and durable co

28、nstruction material.CHAPTER 1INTRODUCTIONCorrosion of metals in concrete is a serious type ofdeterioration that affects concrete in service. Corrosion isseen in parking structures, marine structures, industrialplants, buildings, bridges, and pavements. The FederalHighway Administration published a r

29、eport in 2001 that theestimated cost of corrosion of highway bridges was between$6.43 and $10.15 billion (FWHA-RD-01-097 2001). Thisproblem drains resources in both the public and privatesectors. Implementation of solutions is needed, both in thedesign of structures resistant to corrosion and the re

30、habilitation ofstructures suffering the effects of corrosion.Concrete provides a highly alkaline environment, whichresults in the formation of a passivating film that protects thesteel from corrosion. Corrosion of embedded metals inconcrete can occur, however, if concrete quality and detailssuch as

31、concrete cover and crack control are not adequate; ifthe functional requirement of the structure is not as anticipatedor is not adequately addressed in the design; if the environmentis not as anticipated or changes during the service life ofthe structure; or a combination of thereof. For moredetails

32、 on the mechanism of corrosion of metals inconcrete, refer to ACI 222R.Once corrosion begins, it is aggravated by factors such asmoisture and elevated ambient temperatures. Cracking, straycurrents, and galvanic effects can also exacerbate corrosion.Other causes of corrosion include steel directly ex

33、posed tothe corrosive elements due to incomplete placement orconsolidation of concrete, and industrial or wastewaterchemicals that attack the concrete and the reinforcing steel.Reinforced concrete structures should be designed either toavoid these factors when they are present or be protectedfrom th

34、ese factors when they cannot be avoided.CHAPTER 2DESIGN CONSIDERATIONS2.1Structural types and corrosionCorrosion of steel in concrete was first observed in marinestructures and chemical manufacturing plants (Biczok 1964;Evans 1960; Tremper et al. 1958). The design considerationsrelevant to corrosion

35、 protection depend on the type of structureand its environment and intended use. Certain minimummeasuresfor example, adequate concrete cover and concretequalityshould always be specified, even for structures suchas concrete office buildings completely enclosed in a curtainwall with no exposed struct

36、ural elements. Depending on thetype of structure and its expected exposure, additional designconsiderations can be required to ensure satisfactoryperformance over the intended service life of the structure.2.1.1 BridgesThe primary issues in designing the deck,substructure, and superstructure of a co

37、ncrete bridge forincreased corrosion resistance are knowing the potential forchloride ion exposure while in service and the degree ofprotection required. In theory, the design considerations fora bridge located in a semi-arid region of the U.S., such asparts of Arizona, should be different from a br

38、idge located ineither Illinois or on the coast of Florida. ACI 318, ACI 345R,and AASHTO HB-17 recognize this and contain additionalrequirements for concrete structures exposed to differentlevels of chloride ions in service.There are differences in interpretation when applying theseprovisions for cor

39、rosion protection of bridge structures. Forexposure to deicing chemicals, the top mat of reinforcement ismore susceptible to chloride-induced corrosion than thebottom mat and, therefore, acts as the anode with the bottommat acting as the cathode in macrocell corrosion. AASHTOHB-17 recognizes this an

40、d requires greater concrete coverfor the top mat of reinforcement. This basic premise ofchloride-ion exposure is reversed for a bridge located in awarm climatic area over saltwater where the underside of thebridge deck can be more vulnerable to chloride-ion ingress.Consequently, the concrete cover s

41、hould be increased for thebottom mat of deck reinforcement in this type of application.So much has been written about the bridge deck problemsince the early 1970s that corrosion protection of a bridge super-structure and substructure has sometimes been overlooked.Leakage of chloride-contaminated wat

42、er through expansion andconstruction joints and cracks onto the superstructure,PRACTICES TO MITIGATE CORROSION OF REINFORCEMENT IN CONCRETE STRUCTURES (ACI 222.3R-11) 3American Concrete Institute Copyrighted Materialwww.concrete.orgsubstructure pier caps, abutments, and piers, can lead tocorrosion o

43、f steel in these components. Additionally, snow-removal operations can pile chloride-containing snow aroundpiers, and piers located in marine tidal splash zones are continu-ously subjected to wetting-and-drying cycles with chloride-laden seawater. To design a bridge deck, superstructure, andsubstruc

44、ture with adequate corrosion protection over its intendedservice life of 75 years, as required by AASHTO HB-17, it isimportant to recognize the potential for chloride-ion ingress dueto improper placement or functioning of joints, drains, and otheropenings in the structure.2.1.2 Parking structuresIn

45、many respects, the potentialfor corrosion-related deterioration in a parking structure isgreater than that for a bridge. Because of the intended function ofa parking structure, chloride-laden slush on the underside ofparked vehicles has ample time to drip onto parking decks,increasing the potential

46、for chloride-ion penetration. Also, unlikebridge decks, parking structures, except for exposed roofs, arenot rinsed by precipitation. Moreover, poor drainage permitschloride-laden water to pond on the concrete deck.Design considerations pertinent to corrosion protection ofa parking structure are sim

47、ilar to those of bridge design inthat they depend on location and expected exposure. Corrosion-protection measures for a parking garage constructed inwarm climates, where there is minor or no use of deicingsalts, will be different from one constructed in cold climates,where deicing salts are heavily

48、 used.All structural components for a parking structure locatedin a northern or mountainous climate where deicer chemicalsare used should be provided with additional corrosion-protection measures. Additional corrosion-protectionconsiderations are also needed for parking structures locatedin close pr

49、oximity to marine areas where exposure to saltspray, salty sand, and high moisture conditions is probable.ACI 362.1R contains further recommendations.2.1.3 Industrial floorsThe type of expected exposurewill impact design considerations necessary for corrosionprotection of industrial floors. The primary concern in industrialand manufacturing facilities is exposure to acids or otheraggressive chemicals that can lead to disintegration of theconcrete. Membranes and coatings can protect these floorsfrom their environment.2.1.4 Concrete faadesKnowledge of