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1
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
2
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
3
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
4
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-
5
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
6
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
7
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
8
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
9
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
10
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.
11
• 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.
12
Historical Millitary BldgWW II
Hickam AFB, HI
• Col.umn RepairsModerate Damage
(ZincSheet)
Severe Damage
(DAS Strips)
Overbuilt Columns withDAS Galvanic Strip Anodes
13
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
14
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
15
+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
16
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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