MR2006 Wed 64JCosta
MR2006 Wed 64JCosta
MR2006 Wed 64JCosta
Jorge Costa, P.E. Corrosion Restoration Technologies Division of Structural Group, Inc.
Outline
Corrosion of Steel in Concrete Cathodic Protection Metalized Anode CP Systems Equipment Economic Considerations Case Histories
cover
Corrosion in Concrete
0.02
0.01
0.005
0.002
0.001
0.0005 2 4 6 8 10 12 14
pH
Corrosion in Concrete
Corrosion Cell
Anode Cathode Electrical path between anode
and cathode
Electrolyte (Ionic Path)
Corrosion Cell
Current flow
A
Ionic flow
Corrosion Products
Time to cracking/spalling
Period 1
Period 2
Time
Patch
Anode
Anode
Cathode
REBAR
Ring Effect
Concrete Piles
Cathodic Protection
Cathodic Protection
Reduction or elimination of corrosion by making the metal the cathode in a corrosion cell. This is achieved by means of an impressed direct current or attachment to a sacrificial anode
Cathodic Protection
Delivers a small direct current through the
concrete to the steel. Current is discharged into the concrete from an anode. Previously corroding anodic areas receive current. Anodic areas are converted to cathodic areas. Corrosion is arrested.
CP System Types
Sacrificial or Galvanic Systems Impressed Current Systems
Impressed Current CP
Small Small direct direct current current is is passed passed from from a a permanent permanent anode anode External External power power supply supply connected connected between between anode anode and and steel steel Appropriate Appropriate polarity polarity and and voltage voltage to to stop stop corrosion corrosion process process Current Current can can be be adjusted adjusted for for zones zones according according to to exposure conditions and requirements exposure conditions and requirements
Metalized Coating
TS Coating Characteristics
Zn Metalized Coating
COMPRESSOR
WIRE
+ -
Metalizing Equipment
Case Histories
Parking Garage, PA
Marine Laboratory, FL
Quality Control
Prequalification of Applicators