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Steel Bridge Corrosion Issues

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Steel Bridge Corrosion Issues Presenter: Anthony Peterson – PowerPoint PPT presentation

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Title: Steel Bridge Corrosion Issues


1
Steel Bridge Corrosion Issues
  • Presenter
  • Anthony Peterson

2
Steel Bridge Corrosion Issues
  • Outline
  • Background
  • Chemistry
  • Corrosion Situations
  • Maintenance Strategies
  • Corrective Measures
  • Current Practice
  • Predictive Modeling
  • Conclusions
  • Questions

3
Steel Bridge Corrosion Issues
  • Background
  • Relatively New
  • CSA S16
  • Desired for
  • Consistency
  • Aesthetics
  • Customizability
  • Constructability
  • Variety of Design
  • Main Detractions
  • Corrosion
  • Cost

4
Steel Bridge Corrosion Issues
  • Background
  • Corrosion Issues
  • Cost to United States Infrastructure US276
    Billion, 3.1 GDP (1998)
  • Limited Education
  • Limited Undergraduate
  • Graduate Specific
  • Limited Industrial Guidance
  • Decision Making Problems
  • Government Policy
  • Funding

5
Steel Bridge Corrosion Issues
  • Chemistry
  • Unique Redox Cell
  • Base Steel is Anode Cathode
  • Anode
  • Location of Steel releasing e-
  • Apparent Loss of Steel
  • Cathode
  • Location of Steel accepting e-
  • Apparent Rust
  • Oxygen
  • Electrolyte -- Cl- and other salts

6
Steel Bridge Corrosion Issues
  • Corrosion Situations
  • 1 Atmospheric Zone
  • Moderate Corrosion
  • Low-High Cl- High O2 Low Moisture
  • De-icing Salts
  • 2 Splash Zone
  • Severe Corrosion
  • Highest Cl- High O2 Frequent Wet/Dry
  • 3 Tidal Zone
  • High Corrosion
  • High Cl- High O2 Periodic Wet/Dry
  • 4 Submerged Zone
  • Low Corrosion
  • Variable Cl- Low O2
  • 5 Mudline Zone
  • Low Corrosion
  • Variable Cl- Low O2

7
Steel Bridge Corrosion Issues
  • Corrosion Situations
  • General
  • Uniform Easily seen
  • Expected
  • Usually slow process
  • Localized
  • Particular Can be difficult to see
  • Attempt to avoid
  • Variability in speed
  • Types
  • Crevice
  • Pitting
  • Granular
  • Other

8
Steel Bridge Corrosion Issues
  • Corrosion Situations
  • Type Crevice Corrosion
  • Microclimate
  • Lack of Oxygen initiates Cathode/Anode split
  • Uneven Attack
  • Initiation Theories
  • 1 Critical Crevice Solution (CCS)
  • Generation of Chemical species in Crevice
  • Transportation out of Crevice
  • 2 Critical IR Drop Model (IR)
  • Geometry and Conductivity
  • Current generation and Crevice resistance

Rusting
Cathode
Anode
9
Steel Bridge Corrosion Issues
  • Maintenance Strategies
  • Predictive
  • Planned Mitigation
  • Preventative
  • Inspection and Maintenance
  • Corrective
  • Wait until Corrosion Presents
  • Patch-work type scheme

10
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Paint Coating
  • Inhibitive, Sacrificial, Barrier
  • Touch-Up Painting
  • Simple
  • Little Preparation
  • Not too Disruptive
  • Routine Inspection
  • Moderate Longevity
  • Overcoat Painting
  • Large Undertaking
  • Preparation
  • Disruptive
  • Cost-Benefit Analysis Important
  • Long Longevity

11
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Recoat Painting
  • Large Undertaking
  • The Most Preparation
  • Disruptive
  • Cost-Benefit Analysis Important
  • Greatest Longevity
  • Do-Nothing Approach
  • Social and Economic Issues
  • Cost-Benefit Analysis Very Important

12
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Hot-Dip Galvanization
  • CSA G164
  • Two Defensive Actions
  • (1) Barrier
  • (2) Anodic
  • Expensive
  • Size Limitations
  • In-Field Remediation Issues
  • Cold Galvanization
  • In-Field
  • Small Scale, low preparation
  • Brush, Roller, Spray applications
  • -Electroplating- (Small Scale)
  • Other
  • Mechanical Coating Sheridizing Zinc flakes or
    dust, etc.

13
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Weathering Steel
  • Beneficial, Stable Rust
  • Conditional Implementation
  • No prolonged wetting
  • Wet/Dry cycle necessary
  • Limited concentrations of corrosive pollutants
    de-icing salts
  • Detailing preventing trapped debris and moisture
  • CSA S16.01
  • Types R, A, AT
  • Subject to availability
  • Designed into Bridge
  • Difficult as method of remediation

14
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Thermal Spray
  • Molten Metal Spray, Metallizing CSA G189
  • Zinc or Aluminum
  • Powder coating, substrate heating
  • Impressed Current
  • Electrical Circuit
  • Source of electrons
  • Sacrificial Anode
  • Galvanization is a form
  • Zinc or other metal pieces
  • Uncommon for Bridges

15
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Design
  • Conceptual Design
  • Materials
  • Type of Bridge
  • Type of Use
  • Time Frame
  • Users
  • Other
  • Detailing
  • Drainage
  • Component Interaction
  • Maintenance

16
Steel Bridge Corrosion Issues
  • Corrective Measures
  • Inspection
  • Types
  • Visual
  • Electronic
  • Ultrasonic
  • Thermographic
  • Radiographic
  • Other
  • Schedule
  • Training
  • Cost / Time

17
Steel Bridge Corrosion Issues
  • Current Practice
  • BC Ministry of Transportation
  • 1 Inspection
  • Condition Inspection Report
  • Ratings of Bridge, and its components
  • 2 Decision Maker (Area Manager)
  • Scope and Prioritization
  • Classification (Large, Small, Do-Nothing)
  • 3 Maintenance
  • Large Ministry Involvement (Region Highways)
  • Small Ministry Maintenance Contractors
  • Do-Nothing

18
Steel Bridge Corrosion Issues
  • Predictive Modeling
  • Decision Making Tool
  • Varying Complexity
  • Deterministic
  • Probabilistic
  • Varying Accuracy
  • Maintenance Assumptions
  • Individual Bridge Concerns
  • One Rating
  • Component Ratings
  • Groupings of Bridges
  • Regional Strategies
  • Allocation of Resources

19
Steel Bridge Corrosion Issues
  • Predictive Modeling
  • Methodology
  • User-Friendly
  • Time Value of Money
  • Painting/Coating Focus
  • Additional Input Option
  • Software
  • DecisionPro
  • Microsoft Excel
  • Usage
  • Developed for BC Ministry of Transportation
  • Easily Adaptable

20
Steel Bridge Corrosion Issues
  • Predictive Modeling
  • Deterministic
  • One Steel Bridge
  • Inspection ASTM D610 Rating
  • 8 - 10 Minor Damage
  • 5 - 7 Fair Damage
  • 0 - 4 Severe Damage
  • Annual Funding Estimation

21
Steel Bridge Corrosion Issues
  • Predictive Modeling
  • Input
  • ASTM Corrosion Rating
  • Corrosion Degradation Relation
  • Escalation Rate (Inflation)
  • Interest (TVM)
  • Bridge Surface Area
  • Touch-Up, Overcoat and Recoat Durability and Unit
    Costs
  • Replacement Cost
  • Additional Costs
  • Output
  • Preferred Strategy
  • Predicted Equivalent Uniform Annual Cost (TVM)

22
Steel Bridge Corrosion Issues
  • Predictive Modeling
  • Deterministic
  • Grouping of Steel Bridges
  • Inspection ASTM D610 Rating
  • 8 - 10 Minor Damage
  • 5 - 7 Fair Damage
  • 0 - 4 Severe Damage
  • Additional Input
  • Number of Bridges
  • Additional Output
  • Group Funding
  • Cost-Benefit Analysis of Each Bridge
  • Priority ranking of each Bridge
  • Estimated Annual Funding of Overall Maintenance

23
Steel Bridge Corrosion Issues
  • Conclusions
  • Many Uncertainties
  • Type of Corrosion
  • Location of Corrosion
  • Type of Mitigation
  • Decision Making
  • Education
  • Current Policy
  • Systematic Model

24
Questions?
  • Thank You
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