Table Of ContentCorrosion Inhibitors for Steel in Concrete -
State of the Art Report
EARLIER VOLUMES I N T HIS SERIES
1CorrosionintheNuclearIndustry 19SeaWaterCorrosionofStainless Steels -
Prepared bythe Working Party onNuclear Corrosion Mechanisms andExperiences
Prepared bythe Working Parties onMarine Corrosion and
2PracticalCorrosionPrinciples Microbial Corrosion
Prepared bythe Working Party onCorrosion Education
20OrganicandInorganic Coatings forCorrosion
3General Guidelines forCorrosionTesting of Prevention - ResearchandExperiences
MaterialsforMarineApplications Papersfrom EUROCORR '96
Prepared bythe Working Party onMarine Corrosion
21Corrosion-Deformation Interactions
4Guidelines onElectrochemical Corrosion CDI '96inconjunction with EUROCORR '96
Measurements
Prepared bythe Working Party onPhysico-Chemical 22Aspects ofMicrobially Induced Corrosion
Methods ofCorrosion Testing Papersfrom EUROCORR '96and theEFC Working Party
onMicrobial Corrosion
5Illustrated CaseHistories ofMarineCorrosion
Prepared bythe Working Party onMarine Corrosion 23CO Corrosion ControlinOilandGasProduction
2
- Design Considerations
6Corrosion Education Manual Prepared bytheWorking Party onCorrosion inOiland Gas
Prepared bythe Working Party onCorrosion Education Production
7CorrosionProblems RelatedtoNuclearWaste 24Electrochemical Rehabilitation Methods for
Disposal Reinforced ConcreteStructures-
Prepared bythe V</orkingParty onNuclear Corrosion AStateoftheArtReport
Prepared bytheWorking Party onCorrosion of
8Microbial Corrosion
Reinforcement inConcrete
Prepared bythe Working Party onMicrobial Corrosion
25Corrosion ofReinforcement inConcrete-
9Microbiological Degradation ofMaterials- and
Monitoring, Prevention andRehabilitation
Methods ofProtection
Papersfrom EUROCORR '97
Prepared bythe Working Party onMicrobial Corrosion
26Advances inCorrosion ControlandMaterialsin
10MarineCorrosionofStainless Steels:Chlorination
OilandGasProduction
andMicrobial Effects
Prepared bythe Working Party onMarine Corrosion Papersfrom EUROCORR '97and EUROCORR '98
27CyclicOxidation ofHigh TemperatureMaterials
11CorrosionInhibitors
Proceedings ofanEFC Workshop, Frankfurt/Main, 1999
Prepared bythe Working Party onInhibitors
28Electrochemical Approach to Selected
12Modifications ofPassive Films
Corrosion and Corrosion Control Studies
Prepared bythe Working Party onSurface Science and
Papers from 50th ISE Meeting, Pavia, 1999
Mechanisms ofCorrosion and Protection
13PredictingCO CorrosionintheOilandGasIndustry 29Microbial Corrosion (Proceedings ofthe4th
Prepared bythe Wo2rking Party onCorrosion in Oiland Gas International EFCWorkshop)
Prepared bythe Working Party onMicrobial Corrosion
Production
30 Survey of Literature on Crevice Corrosion
14Guidelines forMethods ofTesting andResearchin
High Temperature Corrosion (1979-1998): Mechanisms, Test Methods and
Results, Practical Experience, Protective Measures
Prepared bythe Working Party onCorrosion byHot Gases
and Monitoring
and Combustion Products
Prepared byF.P.IJsseling and the Working Party on
15Microbial Corrosion (Proc.3rdInt.EFCWorkshop) Marine Corrosion
Prepared bythe Working Party onMicrobial Corrosion
31Corrosion of Reinforcement in Concrete:
16Guidelines onMaterials Requirements forCarbon Corrosion Mechanisms and Corrosion Protection
andLowAlloy Steels forHS-Containing Papersfrom EUROCORR '99and the Working Party on
2
Environments inOilandGasProduction Corrosion ofReinforcement inConcrete
Prepared bythe Working Party onCorrosion inOil and Gas
Production 33Marine Corrosion of Stainless Steels: Testing,
Selection, Experience, Protection and Monitoring
17CorrosionResistant Alloys forOilandGas Edited byD.Feron
Production:Guidance onGeneralRequirements and
TestMethods forH;!SService 34Lifetime Modelling of High Temperature
Prepared bythe Workmg Party onCorrosion in Oiland Gas Corrosion Processes
Production Proceedings ofanEFC Workshop 2001. Edited by
M. Schuize, W.J.Quadakkers andJ.R.Nicholls
18Stainless SteelinConcrete:StateoftheArtReport
Prepared bythe Working Party onCorrosion of
Reinforcement inConcrete
European Federation of Corrosion
Pub lica tions
NUMBER 35
Corrosion Inhibitors for
Steel in Concrete
State of the Art Report
Edited by
B. ELSENER
Publishedfor the European Federation of Corrosion
by Maney Publishing on behalfof The Institute ofMaterials
MANEY
publishing
BookNumber B0773
Published in 2001by Maney Publishing
on behalf ofThe Institute ofMaterials
1Carlton House Terrace, London SW1Y5DB
Maney Publishing isthe trading name of
W.S.Maney &SonLtd
© 2001The Institute ofMaterials
Allrights reserved
ISBN1-902653-48-3
The European Federation ofCorrosion, W.S.Maney and
The Institute ofMaterials are not responsible for any views
expressed in this publication
Typesetting by
spiresdesign
Made and printed in Great Britain
Contents
SeriesIntroduction vii
Preface ix
1.Introduction 1
2.Corrosion Inhibitors for Use in Concrete 3
2.1.Mechanism 3
2.2.Inhibitors as Repair Strategy 5
3.Literature Results on Corrosion Inhibitors for Steel in Concrete 7
3.1.Nitrites 7
3.1.1.Effect ofnitrites on concrete properties 8
3.1.2.Mechanism ofthe action ofnitrites 9
3.1.3.Critical ratio between chloride and nitrite 9
3.1.4.Nitrites as curative inhibitors 12
3.1.5.Long term efficiency 12
3.2.Other Inorganic Inhibitors 14
3.2.1.Inhibitors as admixtures to concrete 14
3.2.2.Sodium monofluorophosphate (MFP) 16
3.3.Alkanolamines and Amines 21
3.3.1.Literature studies and patent applications 21
3.3.2.Studies with proprietary inhibitor blends based on 23
alkanolamines
3.4.Other Organic Inhibitors 33
vi Contents
4.Critical Evaluation of Corrosion Inhibitors 35
4.1.Concrete Properties - Environment 35
4.2.Concentration Dependence 36
4.2.1.Mechanism ofinhibition oflocalised corrosion 36
4.2.2.Inhibitors admixed toconcrete- new structures 37
4.2.3.Surface-applied inhibitors 38
4.3.Measurement and Control ofInhibitor Action 38
4.4.FieldTestsand Applications 39
4.5.Durability ofthe Inhibitor Action 40
5.Test Methods to Evaluate Corrosion Inhibitors for Steel in Concrete 43
5.1.Non-perturbing Tests 43
5.2. Open Circuit Potential 44
5.3.Polarisation ResistanceMeasurements 45
5.4.MacrocellTests 46
5.5.TestVariables 47
5.5.1.Surfacepreparation ofthe rebars - Electricalconnection 47
5.5.2.Pre-passivation 48
5.5.3.Method ofponding 48
5.6.Polarisation Curves 49
5.6.1.Pitting potential 50
5.6.2.Influence oncathodic oxygenreduction reaction 50
6.Ongoing Research Work 51
6.1.Migrating Corrosion Inhibitors 51
6.2.Surface-applied MFP 52
6.3.Testing 52
7.Concluding Remarks 55
8.References 57
9.Abbreviations 65
Appendix: ListofOngoing Research Projects 67
European Federation ofCorrosion Publications
Series Introduction
The EFC, incorporated in Belgium, was founded in 1955 with the purpose of
promoting European co-operation inthefieldsofresearch intocorrosion and corrosion
prevention.
Membership isbased upon participation by corrosion societies and committees in
technical Working Parties. Member societies appoint delegates to Working Parties,
whose membership is expanded by personal corresponding membership.
The activities of the Working Parties cover corrosion topics associated with
inhibition, education, reinforcement in concrete, microbial effects, hot gases and
combustion products, environment sensitive fracture, marine environments, surface
science, physico-chemical methods ofmeasurement, the nuclear industry, computer
based information systems, the oil and gas industry, the petrochemical industry,
coatings, automotive engineering and cathodic protection. Working Parties on other
topics are established as required.
TheWorking Parties function invarious ways, e.g.bypreparing reports, organising
symposia, conducting intensive courses and producing instructional material,
including films. The activities of the Working Parties are co-ordinated, through a
Science and Technology Advisory Committee, by the Scientific Secretary.
The administration ofthe EFCishandled by three Secretariats: DECHEMA e.V.
in Germany, the Societe de Chimie Industrielle in France, and The Institute of
Materials in the United Kingdom. These three Secretariats meet at the Board of
Administrators ofthe EFC.There isan annual General Assembly atwhich delegates
from allmember societies meet to determine and approve EFCpolicy. News ofEFC
activities, forthcoming conferences, courses etc.ispublished in arange ofaccredited
corrosion and certain other journals throughout Europe. More detailed descriptions
ofactivities are given in aNewsletter prepared by the Scientific Secretary.
The output of the EFC takes various forms. Papers on particular topics, for
example, reviews orresults ofexperimental work, may bepublished inscientific and
technical journals in one or more countries in Europe. Conference proceedings are
often published by the organisation responsible for the conference.
In 1987the, then, Institute ofMetals was appointed asthe official EFCpublisher.
Although the arrangement isnon-exclusive and other routes forpublication are still
available, itisexpected that the Working Parties ofthe EFCwill use The Institute of
Materials for publication ofreports, proceedings etc. wherever possible.
Thename ofTheInstitute ofMetals was changed toTheInstitute ofMaterials with
effect from 1January 1992.
The EFCSeries isnow published by Maney Publishing onbehalf ofThe Institute
ofMaterials.
A.D.Mercer
EFCSeries Editor,
The Institute ofMaterials, London, UK
viii SeriesIntroduction
EFCSecretariats are located at:
Dr BA Rickinson
European Federation of Corrosion, The Institute of Materials, 1 Carlton House
Terrace, London, SW1Y5DB,UK
MrPBerge
Federation Europeene de laCorrosion, Societe de Chimie Industrielle, 28rue Saint-
Dominique, F-7S007Paris, FRANCE
Professor Dr GKreysa
Europaische Foderation Korrosion, DECHEMA e. V., Theodor-Heuss-Allee 25,
D-60486, Frankfurt, GERMANY
Preface
Insteel-reinforced orprestressed concrete structures adequate corrosion resistance is
usually provided by a passive layer on the steel surface resulting from the high
alkalinity of the concrete environment. However, as a result of mechanisms which
destroy the passive layer, for example, carbonation ofthe concrete cover or chloride
contamination, depassivation can take place. In such cases it is necessary to take
measures to prevent corrosion induced damage ofthe reinforcement or to keep this
within tolerable limits during the design lifetime ofthe structure. Toavoid some of
the disadvantages oftraditional rehabilitation methods various new methods have
been developed and successfully applied inrecent years. Thus,besides electrochemical
techniques - which have been the subject ofaprevious state ofthe art report from
the EFC Working Party - the use of corrosion inhibitors is continuing to attract
attention.
Inhibitors have been successfully applied forpreventing corrosion and corrosion
damage in many and varied technical fields for very many years. However, the use
ofinhibitors for reinforced concrete structures isarelatively new field and has sofar
been limited to their application as admixtures to fresh concrete or repair products.
More recently their use as asurface-applied procedure has attracted much attention
as it offers a new cost-effective rehabilitation measure for existing structures.
Nevertheless, fornon-experts itisalmost impossible toassess theinhibiting efficiency
ofthe various inhibitive products (inorganic inhibitors, organic inhibitors, inhibitor
blends, etc.) that are proposed.
The preparation of a state of the art report in such a rapidly growing field is
possible only with direct contacts to ongoing research projects, especially to the
European concerted research action COST 521which started in 1997and includes
14different individual projects investigating corrosion inhibitors forsteel inconcrete.
The present state ofthe art report which has been prepared by Bernhard Elsener
with the support ofaTask Group* ofthe EFCWorking Party No. 11on Corrosion of
Reinforcement in Concrete has benefitted from such contacts and describes in detail
the different commercial inhibitors available for use in concrete and considers their
mechanistic action together with experience from laboratory and field tests. The
*The members ofthe Task Group were asfollows:
B.Elsener (Switzerland) - Convenor ofthe Task Group;
c.
Andrade (Spain); R.Polder (TheNetherlands);
A.Legat (Slovenia); P. Schiessl (Germany);
U.Nurnberger (Germany); J.Tritthart (Austria);
C.Page (UK); J.Vogelsgang (Germany).
P.Pedeferri (Italy);
