THE APPLICATION OF ELECTROCHEMICAL CHLORIDE EXTRACTION ON CORRODED BRIDGES

1. THE APPLICATION OF ELECTROCHEMICAL CHLORIDE EXTRACTION ON CORRODED BRIDGES By John Tercha and Connor Wilson

2. American infrastructure: A problem American Society of Civil Engineers (ASCE) reports issues with: • Age • Costs • Stability/durability • Functionality

3. Bridges and corrosion • Material deterioration • Iron and steel • Exposure to elements in the atmosphere • Dangerous • Costly $$

4. The oxygen gets reduced and acts as a cathode. The iron oxidizes and acts as an anode. Both combining to form rust.

5. What is electrochemical chloride extraction (ece) ? • ECE is a rehabilitation method for deteriorating reinforced concrete typically found on bridges above water • concrete: protects • Penetration Chloride ions from the salt in the environment - weakens protective layer from concrete - exposing steel • ECE: use of electrical current to extract chloride ions further strengthening the material

7. Process • Roots in electricity studies and electrochemistry • Steel or titanium mesh: acts as the anode (positively charged surface) • Wire connected to steel rebar making it the cathode (negatively charged surface) • Connected to a rectifier (battery) forming an electrical circuit • Current flow: forming repulsive and attractive behaviors w/ ions • Collected/extracted and released in a gaseous state • Left with material strengthening anions

9. Techniques and installation • Steel or titanium mesh is laid on the effected area • Multiple rectifiers: 900-1000 ft^2 per rectifier - accounting for the entire surfaced • 50v voltage source and current density of 1a/m^2 • Plastic film and sand placed : allow for constant monitoring and recording • Extracted and released • 4-12 week process

11. LAB research and testing • Has been researched since 1973 • Research has proved the effectiveness of ece • Necessary to improve • Harbin institute of technology study • Negative effect discovered: Small amounts of alkali silica gel found Graph showing chloride concentrations decreasing, depending the current levels

12. History and first uses • First introduced in 1973 • First real use in 1989 on Burlington bay skyway bridge, Ontario CA • Proved very effective • Significant drops in dangerous corrosion levels • 1995- 26 uses throughout north America

13. Modern applications • Many states across the country have used ece on highways and bridges • Most prominent: Pennsylvania, Virginia and Iowa • Bridges on i-95 Pictures of ECE being applied to 34th street and 5th street extended Bridges in Virginia. Provided by Virginia Department of Transportation.

14. Other applications in engineering • AFACE- Automated feasibility analysis of cathodic protection or electrochemical chloride extraction • Modern engineering tool • Most efficient method of repair • Computer program decides • Based off of circumstances

15. Flow chart of selection process

16. ECE: The superior method • Other methods: Cathodic protection (cp) and patch repairs • Cp- strengthens steel and concrete - average cost is lower than ece • Patch repairs- small versions of cp • Ece uses titanium: more sustainable • Ece covers more area- more efficient • Extracts more chlorine than cp

17. Efficiency and economic impacts • Duration: 4-8 weeks • Dynamic extraction process • Up to 70% chlorine ions extracted • Standard treatment: $11.90-$12.50/ft^2 • Does not stop traffic • Better alternative to bridge demo- sustainable - prevents significant bridge waste

18. Case studies • De la concorde overpass bridge 9/30/2006 - killing 5 people, injuring 6 • Lowes motor speedway bridge 5/20/2000 - 107 people injured • Corrosion failures/ lack of inspection • Ece: could have prevented

19. Conclusion • America’s bridges: require significant improvement • Corrosion: natural but dangerous process • Ece: successful method of bridge repair - could save up to millions of dollars - sustainable - efficient - constant improvement- stay relevant

20. Thank you