Corrosion Mitigation of Reinforced Concrete Structures Problems after... · Corrosion Mitigation of Reinforced Concrete Structures ... pH around the reinforcing steel. Electrochemical

Deck Problems after Patching 2/16/2016

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Corrosion Mitigation of Reinforced Concrete Structures

Erik Thorp

Vector Corrosion Technologies

Corrosion Ravaged ColumnsChicago, Illinois


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Halo Effect

Corrosion Basics


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Causes of Corrosion

• Chlorides

• Carbonation

• Dissimilar Metals

Results in the Destruction of the Steel’s Passive Oxide Layer

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

γFe2O3

Fe3O4

γFe2O3

Anode

2e -

Cathode

Corrosion Cell in Concrete


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Why Does This Occur?

Corrosion Potential for Steel in Concrete

Metal Voltage

Steel in Chloride-Free Concrete

0 to -200 mV

Steel in Chloride-Contaminated Concrete

-350 to -500 mV

*Typical potentials measured with respect to copper-copper sulfate electrode

Corrosion Cell in ConcreteFe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

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

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


2OH-

Fe3O4

γFe2O3

Fe3O4

γFe2O3

Anode

2e -

Cathode

-350 mV

-200 mV

-500 mV


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“Chip and Patch” Repair Method

© Vector

Patch Accelerated Corrosion

Cathode

Chloride-Free Patch

Chloride Contaminated Concrete

Fe Fe2+ + 2e -

Fe2+ + 2Cl- FeCl2

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


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

2e -Anode-350 mV

-200 mV

-200 mV


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Halo Effect

Halo Effect


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Galvanic Corrosion Protection Systems

Galvanic Protection Systems

• Two different metals are connected in same electrolyte (concrete)

• More “active” metal = anode • More “noble” metal = cathode• Anode corrodes to protect cathode• Natural reaction

– no external power required

• Safe for prestressed concrete


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e -

Galvanic Protection

Partial Galvanic Series

Metal Voltage

Zinc -1100 mV

Steel in concrete

-200 mV to

-500 mV

*Typical potentials measured with respect to copper-copper sulfate electrode

electronic

ionic

CL-

Zinc SteelOH-

K+

Na+

Galvanic anodes naturally operate based on the principle of dissimilar metals corrosion like commonly used batteries. Current flows from the anode (the metal with the most negative potential) to the cathode

(steel).


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Embedded Galvanic Anodes for Corrosion Prevention

Activation Technology

Alkali Activated

• High pH is corrosive to zinc but not to steel

• Allows zinc anodes to provide protection to reinforced concrete over time


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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

Installed Galvanic Anode

Anode Galvanically Protects Surrounding Rebar

Chloride-Free PatchChloride Contaminated Concrete

-1100 mV

-350 mV -200 mV


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Installing anodes around the perimeter of the repair.

Anode Installation

Quick and Easy Installation


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Testing anode connection to reinforcing steel.

Anode Installation

Embedding anodes with repair material.

Anode Installation


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Point Anodes Protection

Base Concrete

Concrete Repair

Point Anodes

Area of Influence

I-94, Jackson, Michigan

Michigan DOT


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Type 1A Embedded Galvanic Anodes

Joints andInterfaces


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Corroded JointPittsburgh, Pennsylvania

Old Retaining Wall

New Concrete Extension

Failed Concrete Next to JointDue to Corrosion

© Vector

Potential Difference Between New Concrete and Old Chloride Contaminated Concrete

Results in Accelerated Corrosion

Old Chloride Contaminated Concrete

New Chloride-Free Concrete Extension

Previous Edge of Old Concrete

New Tied-in Steel

Accelerated Corrosion at Joint Interface


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Old Chloride Contaminated Concrete

New Chloride-FreeConcrete Extension

Galvashield XP Prevents Accelerated Corrosion

Surrounding Rebar is Protected

Anode Galvanically Protects Adjacent Rebar

Bridge Widening Port Mann Bridge, Vancouver, British Columbia


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Embedded Galvanic Anodes -Nomenclature

Type 1

–Installed in Standard Repairs

Type 2

–Installed in Sound Concrete

Source: Installation of Embedded Galvanic Anodes (ACI RAP Bulletin 8, 2010)


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Drilled in Discrete Anodes

Anode Galvanically Protects Surrounding Rebar

Corrosion Activity is Reduced In Rebar

Corrosion Control Anode Installation


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Steel connection next to pre-drilled 2” diameter hole

Anode

Steel Connection

Anode/Steel Connector

2” DiameterHole

Anode Connection to Reinforcing Steel


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Predrilled Holes for CC InstallationParking Garage Deck


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Point Anodesvs.

Distributed Anodes

Point Anodes Protection

Existing Chloride Contaminated Concrete

Concrete Repair

Point Anodes

Area of Influence


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Distributed Anodes Protection

Existing Concrete

Concrete Repair

Distributed Anodes

Area of Influence


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On Many Slab Bridges…

• Slabs are in good condition

• Deterioration at abutment around the key way

Existing Bridge Deck Slab

Spall

Typical Slab Bridge AbutmentApproach Slab


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After Conventional Patching Repair

Abutment Repair Detail With Galvanic Protection

Existing Bridge Deck

± 6-in SCC Facing

#5 @ 18” OC EW ECR

Galvanic Strip Anodes

#5 ECR Dowels

Replace Joint Seal

Approach Slab


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Final Product


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Galvanic Anodes Bridge Deck Overlays


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Corrosion Ravaged ColumnsChicago, Illinois


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Galvanic anodes

0.1

1

10

100

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Time (years)

Cu

rren

t D

ensi

ty (

mA

/m2 )

'Rod' Anodes Point Anodes

Cathodic Protection

Cathodic Prevention

Galvanic Anodes for Corrosion Prevention In New Construction

Galvashield N


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Precast Closure Strip

Galvanode ASZ+Activated Arc Spray Zinc


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DECK PROTECTION

“Distributed” Protection with Activated Arc Sprayed Thermal Zinc


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Activated Arc Sprayed Zinc on Bridge Columns

Electrochemical Treatments

• Chloride Extraction (ECE)

• Re-alkalization

• *Lithium Impregnation (ASR Treatment)


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Electrochemical Chloride Extraction• Temporary electrical treatment applied to passivate

active corrosion by reducing chloride and increasing pH around the reinforcing steel.

Electrochemical Chloride Extraction (ECE)From Salt Contaminated Concrete

ConcreteCl-

Cl-

Cl-

Cl-

Cl-Cl-Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

DC PowerSource

Temporary Anode

ConductiveMedia

Reinforcement


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Cl-

Cl-

Cl-

Cl-

Cl-

Cl-Cl- Cl-

Cl-

Cl-

Cl-

Cl-

OH-

DC PowerSource

ConductiveMedia

Concrete

Reinforcement

Current pathsTemporary

Anode


Cl- Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

Cl-

DC PowerSource

ConductiveMedia

Concrete

Reinforcement

Current paths

OH-

Temporary Anode

Cl-Cl-



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Cl- Cl-Cl- Cl-Cl-

DC PowerSource

ConductiveMedia

Concrete

Reinforcement

Current paths

OH-

Temporary Anode

Cl-Cl- Cl- Cl-

Cl- Cl-


Norcure® ECE Treatment Process


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Norcure® ECE Treatment Process


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Cellulose Fiber Serves as Electrolyte


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Installation CompleteReady to Start Treatment

Several Piers Wrapped and Undergoing ECE TreatmentOmaha, Nebraska


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Piers after ECE TreatmentCleaned and Sealed

Rainbow Bridge- Idaho


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Electrochemical Chloride Extraction

FHWA Bridge Preservation Guide

• In US, 25% of 600,000 bridges are Structurally Deficient or Functionally Obsolete

• 30% of bridges have exceeded their 50 year design life

– Need repair, rehabilitation or replacement

• A need exists to develop adopt and implement systematic process for bridge preservation

• Since 2008, Systematic Preventive Maintenance (SPM) is eligible activity under the Highway Bridge Program

FHWA-HIF-11042, August, 2011


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Corrosion may visit…..

But don’t let it bite!


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Questions

Do we have a few more minutes?

Documents

Corrosion Mitigation of Reinforced Concrete Structures Problems after... · Corrosion Mitigation of Reinforced Concrete Structures ... pH around the reinforcing steel. Electrochemical