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Norcure Chloride Removal Systems

Corrosion OverviewCorrosion Process and Testing

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Background and Introduction

x Corrosion is the single most important problem in

concrete structures

x NACE estimates the cost of corrosion (in the

USA) to be approximately

400 Billion!!!

x Its estimated that 25-30% of this cost is attributed

to corrosion of concrete structures

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Norcure

Causes of Corrosion

x Chlorides

x Carbonation

x Dissimilar Metals

Destruction of Steels

Passive Oxide Layer

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Chloride Induced Corrosion

x Caused by chlorides breaking up passive oxide

layer

x Sources of chlorides:

Marine Environments

De-icing Salts (NaCl, CaCl2)

Chemical Plant Environment

x Vicious Circle: Chlorides are never consumed

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Norcure

Chloride Testing

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Concrete Sample Collection

Norcure

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Rapid Field

Chloride Test Kit

Norcure

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Cover Meter Survey

Norcure

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Corrosion Potential Survey

Norcure

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Norcure

Corrosion Potential Mappingx Example: Norcure Treatment of Starbuck Bridge

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GECOR6 Corrosion Rate Measurement Kit

Norcure

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Measuring Corrosion Rate with GECOR 6

Norcure

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Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

2Fe(OH)2 + 1/2O2 Fe2O3 + 2H2O

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

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

-

2OH-

Fe3O4

Fe2O3

Fe3O4

Fe2O3

Corrosion Cell in Concrete

Anode

2e -

Chloride Contaminated Concrete

Cathode

Norcure

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Corrosion Ravaged Columns Norcure

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Deep Pitting Caused by Chloride Attack Norcure

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Options

forRepair

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x Patch Repair

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Chip and Patch Repair Method

Bridge Deck in Arlington, Virginia Norcure

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Norcure

Patch Accelerated Corrosion

Chloride-Free Patch

Potential Difference Between Patch and

Chloride Contaminated Concrete

Results in Accelerated Corrosion

Chloride Contaminated

Concrete

Norcure

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Patch Accelerated Corrosion

Cathode

Chloride-Free PatchChloride Contaminated Concrete

Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

2Fe(OH)2 +1

/2O2 Fe2O3 + 2H2O

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

-

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

-

2e -Anode

Norcure

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Previous Patch

Failed Concrete Next to Patch

Due to Patch Accelerated Corrosion

Norcure

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New Concrete Jacket

Rust Staining From Steel

Norcure

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x Cathodic Protection

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Cathodic Protection Systems

x Work by applying current to reinforcing

steel to overcome the corrosion process

x Impressed Current Systems: D.C. power

makes electrons flow from anode toreinforcement (cathode)

x Galvanic Systems: Sacrificial metal

corrodes to provide electrons

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Norcure

Permanent

DC Power

Supply

Rebar

Concrete

+

-

Embedded Anode

Concrete Overlay

Distributed Anode CP System

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Norcure

Discrete Anode CP SystemPermanent

DC Power

Supply

Rebar

+

-

Slot Cut for

Wiring Anodes

Drilled Holes for

Discrete Anodes

Discrete Anodes

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Installation of Discrete Anode System

Winnipeg, Manitoba Norcure

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Installation of Discrete Anode System

Winnipeg, Manitoba Norcure

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Memorial Bridge

Daytona Beach, Florida

181 Pile Jackets

Norcure

Rehabilitation Using Distributed Sacrificial Anode CP System

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NorcureElectrochemical

Chloride

Extraction

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Removes Chlorides from the Concrete

Regenerates the Protective Passive Layer

around the Reinforcing Steel

How does Norcure ECE work?

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St. Adolphe Bridge over Red River

St. Adolphe, Manitoba

Manitoba Highways and Transportation Norcure

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Norcure

Net Result - Chloride Extraction

x Chlorides removed from concrete

x Hydroxyl ion formation increases pH aroundreinforcement

x Corrosion pits are deactivated

x Life of structure is extended

See the Norcure Chloride ExtractionPresentation for more Information

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Norcure

Realkalization

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Carbonation

x Reduction of pH in cover concrete which causes

loss of passive oxide layerx Low pH caused by reaction of free lime

(Ca(OH)2) in concrete with atmospheric Carbon

Dioxide (CO2)Ca(OH)2 +CO2 CaCO3 + H2O

lime (soluble) (insoluble) _

pH 12-13 pH < 9

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Realkalisation

x Restores alkalinity to carbonated concrete

x Reinstates passivity of steel reinforcement

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Reakalisation Project

Grant MacEwan Community College

Edmonton, Alberta Norcure

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Net Result - Realkalisation

x Cover zone impregnated with high pH solution

x Low alkalinity rectified

x Entire surface treated

x Life of structure is extended

See the Norcure Re-alkalizationPresentation for more Information

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Patch Accelerated Corrosion

Cathode

Chloride-Free Patch

Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

2Fe(OH)2

+ 1/2

O2

Fe2O3 + 2H2O

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

-

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

2e -Anode

Chloride Contaminated Concrete

Norcure

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Norcure

Embedded Galvanic Anode

ActiveCementitious

Matrix

SacrificialMetal Core

Tie Wires

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Installed Galvanic AnodeChloride-Free Patch

Zn + 2OH- Zn(OH)2 + 2e-

1/2O2 + H2O + 2e-

2OH-

2OH-

2e- 2e-2e -

Chloride Contaminated Concrete

Norcure

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Parking Garage, North York, Ontario

Read Jones Christofferson Norcure

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See the Galvashield Presentation for

more Information