Title: Steel Bridge Corrosion Issues
1Steel Bridge Corrosion Issues
- Presenter
- Anthony Peterson
2Steel Bridge Corrosion Issues
- Outline
- Background
- Chemistry
- Corrosion Situations
- Maintenance Strategies
- Corrective Measures
- Current Practice
- Predictive Modeling
- Conclusions
- Questions
3Steel Bridge Corrosion Issues
- Background
- Relatively New
- CSA S16
- Desired for
- Consistency
- Aesthetics
- Customizability
- Constructability
- Variety of Design
- Main Detractions
- Corrosion
- Cost
4Steel 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
5Steel 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
6Steel 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
7Steel 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
8Steel 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
9Steel Bridge Corrosion Issues
- Maintenance Strategies
- Predictive
- Planned Mitigation
- Preventative
- Inspection and Maintenance
- Corrective
- Wait until Corrosion Presents
- Patch-work type scheme
10Steel 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
11Steel 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
12Steel 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.
13Steel 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
14Steel 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
15Steel Bridge Corrosion Issues
- Corrective Measures
- Design
- Conceptual Design
- Materials
- Type of Bridge
- Type of Use
- Time Frame
- Users
- Other
- Detailing
- Drainage
- Component Interaction
- Maintenance
16Steel Bridge Corrosion Issues
- Corrective Measures
- Inspection
- Types
- Visual
- Electronic
- Ultrasonic
- Thermographic
- Radiographic
- Other
- Schedule
- Training
- Cost / Time
17Steel 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
18Steel 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
19Steel 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
20Steel 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
21Steel 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)
22Steel 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
23Steel Bridge Corrosion Issues
- Conclusions
- Many Uncertainties
- Type of Corrosion
- Location of Corrosion
- Type of Mitigation
- Decision Making
- Education
- Current Policy
- Systematic Model
24Questions?