Cathodic Protection

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A possible cause of structural decay is ‘concrete cancer’. This is caused when water and contaminants seep into concrete and react with the steel reinforcement. The steel reinforcement corrodes and the concrete structure is weakened. To prevent this from happening cathodic protection can be employed.

 

Cathodic protection uses an anode to apply a current to the reinforcement. The steel reinforcement then becomes cathodic and as such resistant to corrosion. This cathodic resistance against corrosion decreases the chances of concrete cancer and potentially increases the structural life of your building or structure.

 

Galvashield

Type 1A Embedded Galvanic Anode Units with 2G Technology

The Galvashield XP range of embedded galvanic anode units utilize an innovative zinc anode core design surrounded by an enhanced formulated cement-based mortar to provide corrosion mitigation to reinforced concrete structures. The anode units are alkali-activated (Type 1A) with an internal pH of 14 or greater to keep the zinc active over the life of the anode while being non-corrosive to reinforcing steel. The anode units utilize 2G Technology™ to provide higher current output. Once installed, the zinc anode corrodes preferentially to the adjacent reinforcing steel, thereby providing galvanic corrosion prevention or corrosion control.

 

Applications

  • Mitigates incipient anode formation (halo effect) in patch repair
  • Bridge widening and other structure modifications
  • Slab replacements, expansion joint repairs and other interfaces between new and existing concrete
  • Repair of prestressed and post-tensioned concrete
  • Chloride contaminated or carbonated concrete
  • Repair of structures with epoxy-coated rebarMitigates incipient anode formation (halo effect) in patch repair
  • Bridge widening and other structure modifications
  • Slab replacements, expansion joint repairs and other interfaces between new and existing concrete
  • Repair of prestressed and post-tensioned concrete
  • Chloride contaminated or carbonated concrete
  • Repair of structures with epoxy-coated rebar

 

Features and Benefits

  • Proven technology – Galvashield anodes have    an extensive 10+ year track record in the field and have received British Board of Agrément (BBA) approval.
  • Type 1A anode – alkali-activated to maintain activity of zinc   while being non-corrosive to reinforcing steel.
  • 2G Technology™ – provides enhanced current output   and protection.
  • Cast zinc core – provides high anode utilization in addition   to a secure long-term connection between the zinc and the   lead wires .
  • Integral steel lead wires – allows for quick and convenient   anode installation.  Provides dependable steel-to-steel  contact with no intermediate materials such as galvanizing  (which can corrode over time) that may compromise  the long-term electrical connection.
  • BarFit™ design – grooved edges on Galvashield XP2 and   XP4 anode units assist with secure anode placement.
  • Economical – provides localized protection where it is   needed the most, at the interface of the repair and the   remaining contaminated concrete.
  • Versatile – can be used for both conventionally reinforced   and prestressed or post-tensioned concrete.
  • Low maintenance – requires no external power source or system monitoring.
  • Long lasting – 10 to 20 year service life* reduces the need for future repairs.
  • Proven technology – Galvashield anodes have    an extensive 10+ year track record in the field and have received British Board of Agrément (BBA) approval.
  • Type 1A anode – alkali-activated to maintain activity of zinc   while being non-corrosive to reinforcing steel.
  • 2G Technology™ – provides enhanced current output   and protection.
  • Cast zinc core – provides high anode utilization in addition   to a secure long-term connection between the zinc and the   lead wires .
  • Integral steel lead wires – allows for quick and convenient   anode installation.  Provides dependable steel-to-steel  contact with no intermediate materials such as galvanizing  (which can corrode over time) that may compromise  the long-term electrical connection.
  • BarFit™ design – grooved edges on Galvashield XP2 and   XP4 anode units assist with secure anode placement.
  • Economical – provides localized protection where it is   needed the most, at the interface of the repair and the   remaining contaminated concrete.
  • Versatile – can be used for both conventionally reinforced   and prestressed or post-tensioned concrete.
  • Low maintenance – requires no external power source or system monitoring.
  • Long lasting – 10 to 20 year service life* reduces the need for future repairs.

 

*As with all galvanic protection systems, service life and performance is dependent upon a number of factors including reinforcing steel density, concrete conductivity, chloride concentration, humidity and anode spacing.

 

Cut-away of Galvashield XP4

 

Level of Protection Description Galvashield XP/XPT Galvashield XP2/XP$
Corrosion Prevention Mitigates initiation of new corrosion activity  –  –
Corrosion Control Reduces on-going corrosion activity  –
Cathodic Protection Reduce or eliminate on-going corrosion activity

 

“Ring Anode” Corrosion (without Galvashield XP)

 

Galvashield XP prevents “Ring Anode” Corrosion

 

Specification Clause

Embedded galvanic anodes shall be pre-manufactured with nominal [add zinc mass] of zinc in compliance with ASTM B418 Type II cast around a pair of uncoated, non-galvanized steel tie wires and encased in a highly alkaline cementitious shell with a pH of 14 or greater. The anode unit shall contain no added sulfate nor shall it contain chloride, bromide or other constituents that are corrosive to reinforcing steel. Anode units shall be supplied with integral unspliced wires with loop ties for tying to the reinforcing steel.

 

How It Works

When two dissimilar metals are coupled together in an electrolyte (in this case concrete), the metal with the higher potential for corrosion (zinc) will corrode in preference to the more noble metal (reinforcing steel). Galvashield XP-type anodes are embedded in concrete repairs to provide corrosion prevention or corrosion control to the reinforcing steel in the adjacent area.

 

Product Anode Details

Anode Name Anode Type Nomimal Dimension (mm) Zinc Mass (g)
XPT 1A-P 125 mm x 25 mm x 25 mm 60
XP 1A-P 65 mm (dia.) x 30 mm 60
XP2 1A-C 70 mm x 65 mm x 30 mm 100
XP4 1A-C 110 mm x 55 mm x 30 mm 160

 

Anode Type and Class

1 – Embedded in Repairs

2 – Embedded in Sound Concrete

A – Alkali-activated using High pH

H – Halide-activated using Corrosive Salts

P – Corrosion Prevention

C – Corrosion Control

 

Installation Instructions

Concrete shall be removed from around and behind all corroding rebar in accordance with good concrete repair practice such as ICRI Guideline R310.1R. Exposed reinforcing steel should be cleaned to remove all residual rust and concrete residue.

The anode units and repair material should be installed immediately following preparation and cleaning of the steel reinforcement. The location and spacing of the units shall be as specified by the designer (refer to design criteria). The units can be placed around the perimeter of the repair or on a grid pattern to protect a second mat of steel if required.

Securely fasten the anode units from the side or beneath the exposed rebar as close as practical to the surrounding concrete (preferably within 4 in. (100 mm)) while ensuring that enough space remains to fully encapsulate the unit in the repair. Wrap the tie wires around the clean reinforcing steel at least one full turn in opposite directions and twist tight for secure connection. The minimum cover of the repair material over the units should be ¾ in. (20 mm).

Anode-to-steel continuity and steel-to-steel continuity within the patch should be verified with an appropriate meter; discontinuous steel should be tied to continuous bars using steel tie wire and re-tested. A value between 0 and 1 ohm should be achieved.

 

Repair Materials

For optimum performance, use a repair material with resistivity less than 15,000 ohm-cm. If a higher resistivity repair material is to be used or if the resistivity of the material is unknown, pack Galvashield Embedding Mortar between the anode unit and the substrate to provide an ionically conductive path to the substrate. Prior to placing the repair material, pre-wet the concrete substrate and the anode units to achieve a saturated surface dry condition, then complete the repair. Do not soak the anode units for greater than 20 minutes.

 

Precautions

Galvashield XP-type anode units are intended to provide localized corrosion prevention or corrosion control and do not address or repair structural or concrete damage. Where structural damage exists, consult a structural engineer. To provide protection to a broader area, install Galvashield CC anode units on a grid pattern or consult us for further product recommendations.

 

Storage

Store in dry conditions in the original unopened box. Avoid extremes of temperature and humidity. Units should be installed within 2 years.

 

Health and Safety

As with all cement-based materials, contact with moisture can release alkalis which may be harmful to exposed skin. Galvashield anode units and Galvashield Embedding Mortar should be handled with suitable gloves and other personal protective equipment in accordance with standard procedures for handling cementitious materials. Additional safety information is included in the Material Safety Data Sheet.

Galvanode

Distributed Anode System for Installation in Wet Environments

Galvanode DAS Marine is a distributed anode system designed to provide corrosion control or cathodic protection to concrete structures in marine environments. Galvanode DAS Marine anode units are alkali-activated which allows for enhanced protection that is not dependent on direct exposure to salt water. This allows the anode units to provide excellent protection to concrete elements exposed to a range of humidity conditions (submerged, splash zone, periodic spray and atmospheric). Galvanode DAS Marine anodes can be used in salt water, fresh water and non-marine applications where the anodes may be exposed to wet conditions during installation.

 

Galvanode DAS Marine anode length, spacing, electrical components and installation procedures are customized to meet specific project requirements. Galvanode DAS Marine anode units are rectangular in cross section [1-1/2 x 3-1/4 in. (38mm x 83mm)] and can be supplied in lengths of up to 7.5 ft (2.3 m). To provide global corrosion protection, evenly distribute Galvanode DAS Marine anode units over the entire structure or combine with bulk zinc anodes to protect submerged and unjacketed areas. The installed anode units are typically encased in reinforced concrete jackets or used in conjunction with concrete or mortar filled stayin-place forms.

 

Application

  • Galvanic jackets for marine columns
  • Bridges, piers and wharves
  • Power and industrial plant rehabilitation
  • Concrete jacketing/section enlargement
  • Service life extension in severe service conditions
  • Installation in wet conditions
  • Conventionally reinforced and prestressed/post-tensioned concrete

 

Features and Benefits

  • Alkali-activated – provides excellent protection in both wet and dry environments.
  • Design flexibility – anode design and spacing can be customized to meet project performance requirements and service life objectives.
  • Economical – anode units can be used in conjunction with locally supplied formwork.
  • Versatile – can be used for both conventionally reinforced and prestressed or post-tensioned concrete.
  • User friendly – installation is quick and easy.
  • Low maintenance – requires no external power source or system monitoring.
  • Measurable – system performance can be easily monitored if required.
  • Long lasting – 20 to 40 year service life* reduces the need for future repairs.

 

*As with all galvanic protection systems, service life is dependent upon a number of factors including reinforcing steel density, concrete conductivity, chloride ion concentration, temperature, humidity and anode spacing.

 

Galvanic anode system on bridge column prior to encasement in concrete jacket

 

Level of Protection Description Galvanode
Corrosion Prevention Preventing new corrosion activity from initiating .
Corrosion Control Significantly reducing active corrosion .
Cathodic Protection Stopping active corrosion by applying on-going electrical current .
Corrosion Passivation Stopping active corrosion by changing the concrete environment around the steel

 

Galvanode DAS Marine Anodes inside stay-in-place FRP Forms

 

Specification

Galvanic protection shall be provided using Galvanode DAS Marine anode units as manufactured by us. The distributed galvanic anode units shall be, alkali-activated with a pH greater than 14 and contain 2 lb. zinc per lineal foot (3kg/m) evenly distributed along the length of the unit. Zinc shall be in compliance with ASTM B418 Type II (Z13000) and ASTM B6 Special High Grade (Z13001) with iron content less than 15 ppm. The zinc shall be formed around a steel core which is continuous along the length of the unit. The anode unit shall be encased in a low resistivity precast cementitious mortar and shall include FRP reinforcing to resist expansion. Anode units shall not contain added sulfates, nor constituents that are corrosive to reinforcing steel as per ACI 222R such as chlorides, bromides, or other halides.

 

How It Works

When two dissimilar metals are coupled together in an electrolyte, the metal with the higher potential for corrosion (more electronegative) will corrode in preference to the more noble metal. In concrete applications, the Galvanode DAS Marine zinc anode unit corrodes in favor of the reinforcing steel and produces an electrical current that mitigates corrosion activity.

 

Design Criteria

Galvanode DAS Marine distributed anode system can be used for corrosion prevention, corrosion control or cathodic protection applications. Anode unit design and spacing are varied to meet project objectives. The anode units are nominally 1-1/2 x 3-1/4 in. (38mm x 83mm) in cross section with lengths up to 7.5 ft (2.3m) and contain 2 lb. per foot (3 kg per meter) of high purity zinc. Galvanode DAS Marine anode unit spacing can vary from 12 in. (300 mm) to 30 in. (750 mm) on center depending upon project objectives, the structure configuration, severity of the service environment and expected service life of the anode components. For assistance with system design, please contact us.

 

Installation Instructions

Galvanode DAS Marine distributed anode systems are used for a wide range of applications. Specific application procedures can be developed on a project-by-project basis. For additional information, please contact us.

 

Precautions

Galvanode DAS Marine distributed anode system is not intended to address or repair structural damage. Where structural damage exists, consult a structural engineer. For optimum performance, encasement concrete resistivity should be less than 15,000 ohmcm. Concrete with significant amounts of polymer or silica fume may have higher resistivity. For applications where direct wetting will not occur during installation, consider Galvanode DAS (nonmarine) anode units. For additional information, please contact us.

 

Packaging

  • Galvanode DAS Marine Distributed Anode System
  • Custom-packaged based on project requirements. For additional information, contact us.

Storage

Store in dry conditions in the original unopened containers for up to one year from date of manufacture. System should be installed within one month of opening container. Take special precaution not to damage anode components during transportation or while handling. Avoid extremes of temperature and humidity.

 

Health and Safety

Contact with moisture can release alkalis which may be harmful to exposed skin. Anode components should be handled with suitable gloves and other personal protective equipment in accordance with standard procedures for handling cement and other alkaline materials. Additional safety information is included in the Material Safety Data Sheet.

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