THE APPLICATION OF ELECTROCHEMICAL CHLORIDE EXTRACTION ON CORRODED - - PowerPoint PPT Presentation

THE APPLICATION OF ELECTROCHEMICAL CHLORIDE EXTRACTION ON CORRODED BRIDGES

BY JOHN TERCHA AND CONNOR WILSON

AMERICAN INFRASTRUCTURE: A PROBLEM

AMERICAN SOCIETY OF CIVIL ENGINEERS (ASCE) REPORTS ISSUES WITH:

• AGE
• COSTS
• STABILITY/DURABILITY
• FUNCTIONALITY

BRIDGES AND CORROSION

• MATERIAL DETERIORATION
• IRON AND STEEL
• EXPOSURE TO ELEMENTS IN THE

ATMOSPHERE

• DANGEROUS
• COSTLY $$

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

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

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

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

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

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

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.

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

Flow chart of selection process

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

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

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

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

THANK YOU