Steel Bridge Corrosion Issues

1. Steel Bridge Corrosion Issues • Presenter: • Anthony Peterson Steel Bridge Corrosion Issues: By Anthony Peterson

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

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

4. Steel Bridge Corrosion Issues • Background • Corrosion Issues • Cost to United States Infrastructure = US$276 Billion, 3.1% GDP (1998) • Limited Education • Limited Undergraduate • Graduate Specific • Limited Industrial Guidance • Decision Making Problems • Government Policy • Funding Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

9. Steel Bridge Corrosion Issues • Maintenance Strategies • Predictive • Planned Mitigation • Preventative • Inspection and Maintenance • Corrective • Wait until Corrosion Presents • Patch-work type scheme Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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. Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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) Steel Bridge Corrosion Issues: By Anthony Peterson

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 Steel Bridge Corrosion Issues: By Anthony Peterson

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

24. Questions? • Thank You Steel Bridge Corrosion Issues: By Anthony Peterson