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Corrosion Protection to Extendthe Life of Concrete Structures

Liao Haixue, P.E. (NY), P.Eng. (ON),Vector Corrosion Technologies

Making Structures Happy Again

Introduction

• Corrosion Evaluation

• Corrosion Basics

• FHWA Bridge Preservation Guide

• Galvanic corrosion protection forconcrete

• Electro-Chemical Chloride extraction

• Electro-Chemical Re-Alkalization

• Post-tensioning evaluation and repairs.

Visual InspectionDelamination SurveyConcrete Cover SurveyCores (Strength + OtherProperties)Chloride Sampling and AnalysispH and Chemical Testing(Carbonation)Corrosion Potential and CorrosionRate

Corrosion Basics

Refining

Corrosion

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Causes of Corrosion

• Chlorides

• Carbonation，CO2

• Different Environment

• Dissimilar Metals

Results in the Destruction of theSteel’s Passive Oxide Layer

Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

2Fe(OH)2 + 1/2O2Fe2O3 + 2H2O

1/2O2 + H2O + 2e - 2OH-

FeCl2 + 2OH- Fe(OH)2 + 2Cl-

2OH-

Fe3O4

γFe2O3

Fe3O4

γFe2O3

Anode

2e -

Cathode

Corrosion Cell in Concrete

Corrosion Cell in Concrete

Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

2Fe(OH)2 + 1/2O2Fe2O3 + 2H2O

1/2O2 + H2O + 2e - 2OH-

FeCl2 + 2OH- Fe(OH)2 + 2Cl-

2OH-

Fe3O4

γFe2O3

Fe3O4

γFe2O3

Anode

2e -

Cathode

-350 mV

-200 mV

-500 mV

Potential Difference Between New Concreteand Old Chloride Contaminated ConcreteResults in Accelerated Corrosion

Old ChlorideContaminated Concrete-250mV

New Chloride-FreeConcrete Extension-100mV

Previous Edge of Old Concrete

New Tied-in Steel

Accelerated Corrosion at Joint Interface

Halo Effect

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New Corrosion Sites

Bridge Pier Bridge Deck

Gunkan Island, Nagasaki,Japan

World Heritage Site

Repair and Incipient anode

FHWA Bridge Preservation Guide

• In US, 25% of 600,000 bridgesare Structurally Deficient orFunctionally Obsolete

• 30% of bridges have exceededtheir 50 year design life

– Need repair, rehabilitation orreplacement

• A need exists to develop adoptand implement systematicprocess for bridge preservation

• Since 2008, SystematicPreventive Maintenance (SPM)is eligible activity under theHighway Bridge Program

FHWA-HIF-11042, August, 2011

Bridge Actions

BridgeReplacement

BridgePreservation

Rehabilitation

PreventiveMaintenance

CyclicalActivities

ConditionBased

Activities

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Examples of PreventiveMaintenance Activities

• Cathodic Protection

– Decks, Superstructures, Substructures

– With or without concrete repairs

• Electrochemical Chloride Extraction

– Decks, Substructures

– With or without concrete repairs

• Cathodic Protection Jackets

– Substructure

FHWA Bridge Preservation Guide (p. 21-23)

e -

How Anode Works

Partial Galvanic Series

Metal Voltage

Zinc -1100 mV

Steel inconcrete

-200 mV to -500 mV

*Typical potentials measured withrespect to copper-copper sulfateelectrode

electronic

ionic

CL-

Zinc SteelOH-

K+Na+

Activation Technology

Alkali Activated

• High pH iscorrosive to zinc butnot to steel

• Allows zinc anodesto provide protectionto reinforcedconcrete over time

Installed Galvanic Anode

Anode Galvanically ProtectsSurrounding Rebar

Chloride-Free PatchChloride Contaminated Concrete

-1100 mV

-350 mV -200 mV

2e -

OH-

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Type 1A Embedded Galvanic Anodesinstalled in Pile Cap Repairs

• Galvanic anodes are directly connected to exposedreinforcing steel in patch repairs to provide localizedprotection from ‘halo’ corrosion.

Current Density

• Cathodic Prevention

– European Standard EN 12696

– Current Density 0.2-2mA/m2

– No polarization criteria

Joints andInterfaces

Corroded JointPittsburgh, Pennsylvania

Old Retaining Wall

New Concrete Extension

Failed Concrete Next to JointDue to Corrosion

© Vector

Bridge WideningCorrosion Prevention

CorrosionMitigation

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Bridge Barrier Wall Corrosion protectionBlackhawk County, Iowa, USA

Bridge Barrier Wall Corrosion protectionBlackhawk County, Iowa, USA

Anode Galvanically ProtectsSurrounding Rebar

Corrosion Activity is

Reduced In Rebar

Galvashield CC Installation

Iowa 192 Viaduct, Council Bluffs, IowaIowa DOT

© Vector

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CC Installation Video

Kansas DOT Galvanic Cathodic Protection System

• Almost certain corrosion protection

• Reduce corrosion rate to approximatelyzero

• Most widely used criterion: 100 mVpotential shift

• Typical applied current: 5 to 15 mA/m2

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Galvanode ASZ+Activated Arc Spayed Zinc Anode

• Humectant-activated metalized zinc anode

• Higher current density and better bondstrength than pure zinc coating

• Designed for inland, drier and colderenvironment

• Provides Cathodic protection to Concretestructures, beams, walls, columns, girderends

• Zinc coating thickness and mass can becustomized to project requirements

• 20 years service life depending on the zinc

Vector Galvanode ASZ+Humectant Activated Arc Spray Zinc For Galvanic

Corrosion Control and Cathodic Protection

Vector Galvanode ASZ+Humectant Activated Arc Spray Zinc For GalvanicCorrosion Control and Cathodic Protection

ASZ+ vs Sealer 9 years later

Galvanic Strip Deck Protection

Ontario Ministry of Transportation

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MTO Galvanic Bridge Deck OverlayTime (days) Temp(oC) Current Density (mA/m2) Depolarization(mV)

13 7 6.5 273

222 20 3.8 271

258 23 2.6 220

267 21 2.5 260

336 23 1.7 211

426 8 1.4 230

486 -20 0.55 142

571 3 1.4 293

655 20 1.7 350

676 20 1.8 313

766 8 1.3 284

789 0 1.1 276

859 -7 0.8 167

942 10 1.4 330

1040 25 1.6 353

1165 7 1.24 281

1299 -3 1 201

1433 22 1.5 501

1573 0 7.6 322

1649 3 1.1 314

1755 20 1.6 421

2000 -5 0.65 273

3174 22 1.8 2783646 23 1.13 3884285 25 1.08 403

401 Warden Ave Underapss

Island Park Bridge (417) with DASanodes, Ottawa, Canada

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Case StudyIsland Park Drive Overpass, Ottawa

Stem walls– Spalls and delaminations covers approximately 14.5% (36.5m2)

and 10.5% (28m2) of the exposed faces of the east and westabutments respectively

– Chloride contents at the steel level of west and east abutmentsare 0.111% and 0.297% respectively, which are well above thethreshold of 0.025% by mass of concrete inducing corrosion

– Over 95% (238.5m2) and 74.5% (204m2) of the east and westabutments respectively exhibit corrosion potentials morenegative than the threshold valur of –0.35V required to inducecorrosion in the reinforcing steel.

Wingwalls• North wingwalls are in good condition, however 100% (36.1m2)

and 97% (63.6m2) of the northeast and northwest wingwallsrespectively, exhibit corrosion potentials more negative than thethreshold value of –0.35V required to induce corrosion in thereinforcing steel

• South wingwalls exhibit severe delamination with 55% and 20%concrete delamination and spalling for southeast and southwestwingwalls respectively.

Chloride Contaminated Concrete

Potential Difference BetweenUpper Steel In Chloride Contaminated Concreteand Lower Steel Results in Accelerated Corrosion

© Vector

Highway 417 Island ParkOverpass, Ottawa, Canada

• Rapid Deck Structurereplacement overnight

• Substructure rehabilitation withGalvanic anodes, designed tolast as long as the new deck.

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• Rapid Bridge Replacement Video

Island Park Drive, Ottawa, Canada

Case Study, DAS anodesfor Marine piles

• 1008 piles total ）

• DAS anodes are designedfor 40 years life

• 5-year monitoring datasuggests the anodes lastmore than 60 years.

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Historical Millitary BldgWW II

Hickam AFB, HI

• Col.umn RepairsModerate Damage

(ZincSheet)

Severe Damage

(DAS Strips)

Overbuilt Columns withDAS Galvanic Strip Anodes

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Cl- Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

DC PowerSource

Conductive

Media

Concrete

Reinforcement

Current paths

OH-

TemporaryAnode

Cl-

Cl-

Electrochemical Chloride Extraction (ECE)From Salt Contaminated Concrete

Burlington Skyway, Burlington, OntarioMinistry of Transportation Ontario

© Vector

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First North American Norcure Project1989 Burlington Skyway, Burlington, Ontario

Ministry of Transportation of Ontario

Burlington Skyway - CorrosionPotential Measurements

North Face West Face(Untreated) (ECE Treated)

200 to 200 to<200 350 >350 <200 350 >350

Pre-Treatment 0 85 15 0 96 41 Yr. After 41 59 0 98 2 02 Yr. After 41 59 0 100 0 03 Yr. After 26 74 0 96 4 04 Yr. After 26 70 4 98 2 05 Yr. After 19 74 7 96 4 06 Yr. After 26 59 15 96 4 07 Yr. After 30 63 7 96 4 08 Yr. After 11 78 11 96 4 09 Yr. After 15 78 7 96 4 0

Note: Values represent percentage of readings within range(negative signs omitted)

(mV vs Cu-CuSO4)

+ve

-ve

Anode Electrolyte

Reinforcement

Concrete

Norcure® Re-alkalization

+ve

-ve

Anode Electrolyte

Reinforcement

OH-Concrete

Norcure® Re-alkalization

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+ve

-ve

Anode Electrolyte

Reinforcement

OH-Concrete

Norcure® Re-alkalization

+ve

-ve

Anode Electrolyte

Reinforcement

Concrete

Na2CO3 & NaHCO3

Norcure® Re-alkalization

Conditions

Norcure® Re-alkalization

Reagan National Airport FacadeWashington, DC

Corrosion of Steel Frame Buildings

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ICCP-Cathodic ProtectionSystems

• Work by applying current to reinforcingsteel to overcome the corrosion process

• Galvanic Systems can meet this criteria

• Impressed Current Systems:

– D.C. power makes electrons flow fromanode to reinforcement (cathode)

– Requires On-going Adjustments &Maintenance

Steel Frame ICCP

_

+

Mortar /Brick Infill

Steel

Cathodic protection

We do nothing, anodes work hard everydayextending service life

Making Structures Happy Again

Topics covered:- Corrosion basics- Galvanic protection- Chloride extraction- Re-alkalization- Impressed Current Cathodic Protection

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