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DuoGuard™ Hybrid Anode

Stops corrosion and extends structural life.

  • 2nd generation targeted protection
  • 20 – 50 years protection
  • Benefit of both impressed current and galvanic cathodic protection, no permanent power source required
  • Manufactured in the UK to ISO9001 and ISO 14001

Our unique DuoGuard™ range of discrete anodes features innovative dual technology to arrest steel reinforcement corrosion within 7 days. DuoGuard™ is installed into concrete structures to stop reinforcing steel corrosion caused by chloride salts and carbonation. It can be used to protect contaminated but unspalled concrete saving the time and cost of replacing the concrete material. With a long system lifetime the DuoGuard™ anode provides a cost effective, maintenance free method of corrosion protection.

DuoGuard™ is not available in all regions. Contact CPT for further advice.



DuoGuard™ combats the two main types of corrosion found in reinforced concrete structures.

Carbonation induced – exposure to atmospheric carbon dioxide combined with prolonged contact to sufficient moisture and oxygen can leave steel vulnerable to corrosion.

Chloride induced – if chloride in the form of inherently mixed set accelerators or external aggressive salts permeates reinforced concrete in sufficient quantities, an aggressive form of corrosion can be initiated.

When either or both of these take hold in a structure, this can lead to the concrete cracking and being displaced as the steel reinforcement expands and pushes out. The corrosion and its effects often propagate very quickly – so it is crucial to be proactive in assessing and fixing the issue.

Corrosion Image

DuoGuard™ Anodes

CPT DuoGuard™ anodes feature new generation electro-chemical technology to stop reinforcing steel corrosion caused by chloride salts and carbonation for up to 50 years.

The full package: CPT also supplies all the ancillary materials needed for DuoGuard™ installation, including wires, connectors and embedding mortar.

Anodes are available in 5 sizes to suit any structure:

DuoGuard™ 175: 42 mm long x 18 mm diameter
DuoGuard™ 350: 77 mm long x 18 mm diameter
DuoGuard™ 500: 110 mm long x 18 mm diameter
DuoGuard™ 750: 165 mm long x 18 mm diameter
DuoGuard™ 1000: 220 mm long x 18 mm diameter

DUOGUARD™ - duoguard how it works 1
Anodes connected to external power supply


DuoGuard™ anodes are installed into contaminated areas of reinforced concrete, identified as being at risk of corrosion, by simply drilling 30mm diameter holes and embedding the anodes in DuoCrete SD mortar. These are then temporarily connected in groups to a power supply using titanium wire – just a couple of connections are required for a circuit of up to 200 anodes. The system is discrete with no surface wiring or permanent control systems – totally vandal proof.

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Application of DuoCrete embedding mortar

How it works

DuoGuard™ is a hybrid treatment. During treatment a sacrificial anode is used as both an impressed current and galvanic anode. Initially, a constant voltage power supply is used to drive a high current from the installed anode to re-passivate the corroding steel, typically for one week. The same anode is then connected directly to the steel to provide maintenance free cathodic protection by means of a galvanic current. The hybrid system means that the requirement for a permanent power supply is eliminated and DuoGuard offers the advantages of a galvanic anode system, requiring little to no maintenance. The system can be designed to meet BS EN ISO 12696:2016 the international standard for cathodic protection.

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DuoGuard™ – Long Term Performance Data

The graph below shows the protective current produced by a zone of eight anodes over a 15 year period at Whiteadder Bridge. This bridge spans a flood plain and DuoGuard™ hybrid anodes were installed into the bridge piers to control corrosion back in April 2007. The anodes can be seen to be extremely reactive to local conditions with peaks in current output coinciding with river floods and soaking of the bridge piers. During drier times the current is reduced and anode life is preserved. Corrosion rate measurements have been independently taken by Aecom and these demonstrate that the steel has remained passive throughout the monitored period as defined by the international standard for cathodic protection of steel in concrete BS EN ISO 12696:2016. Whiteadder Bridge is one of many sites where long term performance has been monitored, providing reassurance that the DuoGuard™ system will provide reliable, self-regulating, maintenance free protection.

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Whiteadder River Bridge, Northumberland – DuoGuard Hybrid anodes installation
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Downloads & Case Studies

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    DuoGuard™ Installation

    Benefits of DuoGuard™

    • Rapid inhibition of steel corrosion
    • Protects contaminated unspalled concrete – saves concrete replacement
    • Lifetime cost effective solution
    • World leading technology
    • Easy to monitor performance
    • No permanent power supply: no ongoing costs or maintenance required
    • Large charge capacity: lifetime of up to 50 years*
    • Flexible system size: can be targeted to an area or installed over an entire structure
    • Impressed current can be reconnected at any time
    • No expensive control equipment needed

    *dependant on local site conditions and anode size