Concrete Cathodic Protection De Nora

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ELECTRODE TECHNOLOGIES & WATER TECHNOLOGIES
CATHODIC PROTECTION

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De Nora Cathodic Protection Markets
The Markets We Serve
Concrete structures that support our lives and economy are
everywhere. Bridges, parking garages, cooling towers
and marine facilities are often located in or near salty environments
that cause the steel re-enforcing bars in the concrete to rust. The
rusting steel breaks apart the concrete and weakens the structure.
the markets we provide cathodic protection anodes for include:

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De Nora Cathodic Protection Markets
Typical Concrete Structures that need cathodic protection
Docks, wharfs, jetties, piers and seawalls
Oil and gas reinforced concrete infrastructure
Transportation (including bridge decks and substructures)
Parking garages
Power and energy support structures
Coastal buildings
Steel frame masonry buildings
Monuments, statues and theme parks

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Corrosion of Steel in Concrete
INITIALLY, STEEL IN CONCRETE IS PROTECTED FROM CORROSION
pH > 11 FORMS PROTECTIVE FILM ON SURFACE
CONCRETE COVER ACTS AS SEMI-BARRIER
STEEL IS SAID TO BE PASSIVATED

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OVER TIME, THE PROTECTION OF STEEL IS DESTROYED BY:
MOISTURE
OXYGEN
CHLORIDES (SALT)
CARBON DIOXIDE
ACIDIC CHEMICALS

CHLORIDES COME FROM SALT
ROAD DE-ICING SALTS IN SNOWY CLIMATES
SALT WATER IN MARINE ENVIRONMENTS
AIR-BORNE SALT IN SEASIDE AND COASTAL AREAS
INHERENT IN THE CONCRETE FROM THE AGGREGATE
(BEACH SAND)
ADDED TO THE CONCRETE MIX (CALCIUM CHLORIDE)
CHEMICAL ATTACK IN INDUSTRIAL FACILITIES

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RUST AND CORROSION OF STEEL
RE-ENFORCING BARS:
DELAMINATION OF CONCRETE
CREATES AN EASY PATH FOR
MORE SALT AND CHLORIDES
RUST AND CORROSION LEAD TO
BREAKAGE AND LOSS OF REBAR
STRUCTURAL WEAKENING

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Cathodic Protection
Cathodic Protection was first described by Sir Humphry Davy in a series of papers
presented to the Royal Society in London in 1824. Thomas Edison experimented with
impressed current cathodic protection on ships in 1890 but was unsuccessful due to lack
of a suitable current source and anode material. In the USA, by 1945, CP was being
applied in the oil & natural gas industry.
The simplest method to apply CP is by connecting the metal to be protected with another
more easily corroded “Sacrificial Metal” to act as the anode of the electrochemical cell.
The sacrificial metal then corrodes instead of the protected metal. When passive galvanic
CP is not adequate, then we provide an external DC source.
Common applications are: Steel crude, natural gas, water or oil pipe lines, storage tanks,
ship & boat hulls, offshore platforms, steel reinforced concrete bridge decks, pilings,
marine dolphins and pier structures, and metal reinforcement bars in concrete buildings.
Why it is important ? Corrosion costs money. Corrosion of metals cost the economy
almost $300 billion per year and it is estimated that 1/3 of it can be controlled by better
techniques like cathodic protection. Corrosion affects various market sectors such as
infrastructure, manufacturing, production, defense.

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4 Components of Corrosion
ANODE (corrosion occurs, chlorides)
CATHODE (protected area)
ELECTROLYTE (concrete)
METALLIC PATH (rebar)

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Impressed Current Cathodic Protection
A small DC current flows
from an anode material,
installed in the structure,
to the rebar.
Rebar becomes the
cathode and is protected.
Most effective system for
controlling corrosion
AC Power is required near
the bridge.
Requires monitoring to
make sure the power
supply is on.

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Extensive track record (> 2,000 concrete structures protected
worldwide)
Minimum 40 year anode life expectancy
Grade 1 Titanium substrate
Mixed-Metal Oxide (MMO) sintered coating
Available in mesh and ribbon form
Titanium Based Impressed Current Anodes
Impressed Current Cathodic Protection
Since 1986, De Nora’s Lida and Elgard™ mesh and ribbon anodes have
been providing cathodic protection and stopping corrosion of
reinforced concrete structures. These long-life titanium based
mixed metal oxide anodes are specified around the world more
than any other anode system.

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ELGARD™ Titanium Based Anodes
Long Anode Life (>75 Years)
Extensive track record (>2 million m2)
Dimensionally Stable Anode (DSA)
First Manufactured in 1985
Manufactured by De Nora Tech, LLC.

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Bridge Deck ICCP w/ Titanium anodes
Durability
Anode – Excellent long life > 40 years
Overlay – Excellent long life >40 years, Surface prep and bond is
critical. LMC, Low slump, HES are OK
Power Supply – Good, life about 20 years
Cost - Initial
Cathodic Protection – Installed cost = $8 - $10/SF depending on size
and construction phasing
Overlay – Installed cost = $5 - $8/SF depending on size and
construction phasing

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Bridge Deck ICCP w/ Titanium anodes
Cost - Annual
Budget for $1,000/year to cover monitoring and rectifier replacement
in year 20.
Constructability
Excellent – System is designed to be an add on to existing bridge deck
rehabilitation schemes.
Does not add any additional time to the schedule.
Traffic Impacts
No more than the chosen rehab technique during construction.
Extends deck life and improves rideability.

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ELGARD™ Titanium Mesh
Manufactured in 3 sizes. Current
requirement determines the required
size. Each roll has 1,000 sf.
ELGARD 150: Used for lightly
reinforced structures such as
balconies and parking decks.
Can provide up to 1.5mA/sf of
concrete surface area.

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ELGARD 210: Used for medium
reinforced structures such as
bridge decks. Can provide up
to 2.1 mA/sf of concrete
surface area.

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ELGARD 300: used for heavily
reinforced structures such
as beams and columns. Can
provide up to 3.0 mA/sf of
concrete surface area

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Coastal Substructures
Bridge Substructures
Piers and Wharfs
Corrosion of Substructures in
Tidal Zone and Splash
Zones
Both Impressed current and
galvanic systems are used
for protection
Corrosion of Pre-stressed Concrete Piling

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Failed pile jacket without cathodic protection

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Corrosion of Conventionally reinforced concrete pile

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ELGARD™ Titanium Ribbon
Same Grade 1 titanium and MMO
coating as mesh
3 available widths:
ELGARD 85 (3/8”, 0.85mA/sf)
ELGARD 100 (1/2”, 1.0mA/sf)
ELGARD 150 (3/4”, 1.5 mA/sf)
Current Requirement determines
size and spacing
Maximum spacing usually 12”

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Clipped to rebar for new construction or rehabilitation

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Installed in saw cut slots
on existing deck with
grout backfill

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Structures Utilizing De Nora ICCP Products
• Prime ministers residence, Dublin, Ireland 1991. Protection of steel in stone clad beams. Tested two years ago and still
working;
• Inigo Jones Arch, London, England 1995. Masonry arch with iron cramps. Tested four years ago and still working;
• Gloucester Road Tube Station, London, England 1997. Protection of steel girders behind a listed tiled façade. Operated
successfully for 6 years. They then noticed the untreated areas of girders had corroded so badly they were structurally
unsound so upper façade was removed and rebuilt.
• Lloyds Bank Headquarters, London, England 1998. Operated successfully until 2009 when structure gutted and reused as a
shopping mall. English Heritage are currently pressing new owners to reinstall CP;
• Carillion War Memorial, New Zealand, 1999. Bell tower. Last year was checked and working well;
• Glasgow Dental Hospital, Scotland 2001. Stone on steel girders in building. Still functioning with automatic control system;
• Elk War Memorial Building, Chicago, USA 2011. Steel girders in cut ashlar stone. Still working well;
• Alcatraz Prison, San Francisco , USA 2013. Steel girders and steel reinforcement in concrete and stone. Trial successful;
• Reichenbach Museum, Germany, 2006. Stone on steel girders in old building. Still functioning with automatic control system;
• Rheims Market Hall, France 2008. Old building with steel corroding. Automatic control system. Checked this week remotely
and producing text book results;
Other projects in the USA
Yale University
Harvard University
New York University (Plattsburgh -journalism buildings)
Plymouth Bretheren Memorial
Chicago Tribune Building
A brief description of 10 Cathodic Protection projects given below:

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Sydney Opera House, Sydney, New South Wales, Australia

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Christ the Redeemer statue of Jesus Christ in Rio de Janeiro, Brazil

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National Cooperative Highway Research Program
NCHRP Synthesis 398
“Cathodic Protection for Life Extension of Existing Reinforced Concrete Bridge Elements”
A Synthesis of Highway Practice
Consultant:
Ali Akbar Sohanghpurwala
Concorr, Inc.
Sterling, VA
Research Sponsored by the American Association of State Highway and Transportation Officials in
Cooperation with the Federal Highway Admin.
Transportation Research Board
Washington, DC
2009
www.trb.org
United States Government Study of
Cathodic Protection

Concrete Cathodic Protection De Nora

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