CATHODIC PROTECTION OF REINFORCED CONCRETE STRUCTURES

Slides:



Advertisements
Similar presentations
Outline Curriculum (5 lectures) Each lecture  45 minutes
Advertisements

Corrosion of Steel Reinforcement in Concrete
for Pipelines & Casings
Department of Chemistry
Cathodic Protection of Steel in Concrete
Civil Engineering Materials
Y12 HSC Chemistry Shipwrecks and Corrosion R. Slider
Metals Nat
Created by C. Ippolito March 2007 Updated March 2007 Chapter 22 Electrochemistry Objectives: 1.describe how an electrolytic cell works 2.describe how galvanic.
Distress, Evaluation, and Repair of Historic Concrete Jarkko Simonen, P.E. Wiss, Janney, Elstner Associates, Inc.
ACADs (08-006) Covered Keywords Cathodic protection, corrosion. Description Supporting Material
Electrolytic Cells Is a Galvanic Cell forced to operate in reverse Process is called electrolysis This occurs if a voltage greater than that produced by.
CONTROL OF CORROSION ON UNDERWATER PILES
Lesson 2. Galvanic Cells In the reaction between Zn and CuSO 4, the zinc is oxidized by copper (II) ions. Zn 0 (s) + Cu 2+ (aq) + SO 4 2-  Cu 0 (s) +
Corrosion & Associated Degradation
Cathodic Protection Presentation on Cathodic Protection System, at IOCL KBPL Kandla. Dt By Corrosion Matters Hyderabad An Advisory services.
Corrosion of Metals.
Anita Marcia Jane. Methods :  Prevent the corrosive environment from getting at the metal  Use electrochemical principles to prevent corrosion.
Properties of Materials & Corrosion Eng. Shadi Sawalha.
Chapter 3 Cement.
Introduction Atmospheric Corrosion Prevention Methods What are Mg alloys? Mixture of metals to form a stronger and more corrosion resistant metal Mainly.
 Deals with the relation of the flow of electric current to chemical changes and the conversion of chemical to electrical energy (Electrochemical Cell)
Metals, Making Electricity and Corrosion. Metals The job that a metal is used for is determined by its physical and chemical properties. Physical properties.
Cell potential is related to concentrations Electrodes can be used that are sensitive to specific ions They measure concentrations of specific ions which.
Chapter 17 Corrosion and Degradation of Materials.
The Use of Zinc Anodes to Extend the Life of Concrete Patch Repair Jack Bennett J.E. Bennett Consultants, Inc.
Shipwrecks, Corrosion and Conservation Summary Slides PART 3 – Jack Dengate.
At 25°C an aqueous solution will be acidic if a. [H3O+] > [H2O] b. [OH-] = [H3O+] c. [H3O+] > M d. [OH-] > ‑ M Answer: C.
Shipwrecks, Corrosion and Conservation Summary Slides PART 6 – Jack Dengate.
Chemistry Chapter 19 D.  Defined: branch of chemistry that deals with electricity-related redox reactions  Electrochemical cell: ◦ System of electrodes.
Section 14.2 Voltaic Cells p Voltaic cells Voltaic cells convert chemical energy to electrical energy. In redox reactions, oxidizing agents.
FACULTY OF ENGINEERING IN SHOUBRA BENHA UNIVERISITY ASSESSMENT OF FRESH AND HARDENED CONCRETE TREATED WITH CORROSION INHIBITORS BY YASSER ABDELGHANY FAWZY.
Impressed Current Zebra Cassette CorroDiscSurface Embedded Sacrificial Anode ZLA Roll Anode GSC Super Anode Clip On Anode Monitoring and Control Camur.
Institute of Building Materials Research Conservations Repair and Polymer Composites RWTH Aachen University, Germany “Who`s managing the quality in the.
Cathodic protection of steel in concrete Guided by: prof. R.j.shah prepared by: Bhrugesh patel SD1210 SD1210.
Unit 13: Non-ferrous metals Dr
Definition of Corrosion
CORROSION MITIGATION OF A PIPELINE
Engineering Chemistry CHM 406
How long will your concrete bridge last?
Engineering Chemistry (revised edition)
Chapter 13: Non-ferrous metals
Basic Corrosion Theory
REMEDIAL TREATMENT OF CORRODED REINFORCED CONCRETE STRUCTURES
DURABILITY OF CONCRETE STRUCTURES RURAL POLYTECHNIC TARIHAL
Corrosion Objectives Corrosion process Environmental factors
Corrosion Control methods
BASICS CORROSION Cells
Chapter 21: Electrochemistry
Magnesium Alloy Corrosion
How long will your concrete bridge last?
Electrochemical Cells
BIMETALLIC CORROSION WORKSHOP
Standards, Best Practice Guidances and Thresholds
CATHODIC PROTECTION 5,1 INTRODUCTION
Electrochemistry.
Corrosion & Associated Degradation
Engineering Unit – Chemistry Section
Corrosion Part 3 Corrosion Protection Methods
ISSUES TO ADDRESS... Why does corrosion occur ? 1 What metals are most likely to corrode? How do temperature and environment affect corrosion rate? How.
Ship Related Corrosion Topics
Corrosion Control Must be addressed at the design stage
Electrochemistry AP Chapter 20.
Engineering Materials
Prevention and Control of Corrosion
Metals.
Voltaic Cells/Electrochemical Cells/Spontaneous Reactions
Y12 HSC Chemistry Shipwrecks and Corrosion R. Slider
Additional electrochemistry
Redox in Electrochemistry
Presentation transcript:

CATHODIC PROTECTION OF REINFORCED CONCRETE STRUCTURES Center for Engineering Research Research Institute, KFUPM

REINFORCEMENT CORROSION Passivity High pH leading to formation of passive layer Chemical binding of chlorides Dense and relatively impermeable structure of concrete Depassivation Chloride ingress Carbonation

Chloride-induced Reinforcement Corrosion Due to external chlorides Due to chloride contamination from the mix constituents

Chloride Limits ACI 318 (0.1 – 0.15%; water soluble) ACI 224 (0.2%; acid soluble) BS 8110 (0.4%; total)

CARBONATION Ca(OH)2 + CO2  CaCO3 + H2O Reduction in pH (up to 8.5)

FACTORS AFFECTING CARBONATION Concrete quality Concrete cover Moisture condition Temperature Chloride-sulfate contamination

PREVENTION THROUGH DESIGN Cover over reinforcing steel Water-cement ratio Cement content Cement type

PROTECTION OF STEEL Metallic coatings Non-Metallic coatings Inhibitors Electrochemical protection Cathodic protection Chloride removal Realkalization

CATHODIC PROTECTION Sacrificial anode Impressed current

Corrosion cell in concrete

Corrosion cell in a repaired concrete

Corrosion cell after CP

Comparison of CP systems (Merits) Impressed current system Sacrificial anode system Longer anode life Inherently simple Current can be controlled No monitoring and maintenance No requirement for electrical isolation Risk of hydrogen embrittlement on high strength steel is minimal Saw cutting and concrete encapsulation for anodes is not required

Comparison of CP systems (Demerits) Impressed current system Sacrificial anode system Requires monitoring and maintenance Short anode life Electrical isolation required between anode and steel Anode current delivery is dependent on anode chemistry and surrounding environment Conduit and wiring required Current cannot be adjusted or controlled

Sacrifical Anode System Anode material Alloys of Mg, Al, Zn Anode shapes Zinc foil (Zinc hydrogel) Metallized zinc (thermal spray) Jackets Zinc capsules or discs encased in mortar

Corroded pile in sea

Pier with SACP

Discrete anode for repaired structure

Discrete anode

Placement of discrete anodes

Mesh anode

Placement of anodes

Specimens with discrete anodes

Specimens with jacket anodes

Specimens with mesh anodes

Specimens and measurement boxes

Sacrificial Anode

Impressed Current CP

ICCP Anodes Conductive coating Arc sprayed zinc Titanium anode mesh Sparyed, rolled or brushed over a nibium wire (300 um thickness) Arc sprayed zinc Spraying metal on concrete with compressed air (300 -400 um) Titanium anode mesh Titanium anode mesh jackets Titanium ribbon Discrete anodes Thermally sprayed titanium

Current requirements Atmospheric zones Under water Decreases with time 5 to 15 mA/m2 Under water 0.2 to 2 mA/m2 Decreases with time

ICCP – Power System Transformers/Rectifiers Constant voltage/current system Stable over long period of time Solar- or wind-powered units are also used

ICCP - Connections Durable and corrosion resistant Low-voltage wires Diameter for minimum voltage drop Color coded Multiple connections and cables recommended

ICCP Monitoring System Potential measurements Embeddable reference electrodes Ag/AgCl Mn/MnO2

Anode mesh fixed on concrete

Conductor bar welded to anode mesh

Negative connection to the steel bar

Connection of embedded items

Reference electrode

Installing overlay

Finishing operation

Anode and steel cage

Details of anode

Connection of anode ribbon to the titanium conductor bar

Steel connection

Placement of electrodes and connections to the steel bar

Pouring of concrete

Chloride Removal

CE - Details Anode Electrolyte Current Time Titanium or steel mesh Electrolyte Water or saturated calcium hydroxide solution Current 1 to 2 A/m2 Time 6 to 10 weeks Not advisable for prestressed concrete Impressed/sacrificial anode cathodic protection systems may be used Side effects – Alkali-silica reaction

Re-Alkalization

Realkalization - details Anode Steel or titanium mesh Electrolyte Sodium carbonate solution (1 mole/L) Current 1 to 2 A/m2 Time Days to weeks Not advisable for prestressed concrete Impressed/sacrificial anode cathodic protection systems may be used Side effects – Alkali-silica reaction

THANK YOU