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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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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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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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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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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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Permanent
DC Power
Supply
Rebar
Concrete
+
-
Embedded Anode
Concrete Overlay
Distributed Anode CP System
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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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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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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
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