General Engineering
Two weeks prevention, 50 years cure

Sika’s new galvanic anode system delivers up to 50 years concrete corrosion protection without monitoring or maintenance. Owners of large, corrosion prone concrete assets such as wharves, bridges, sea walls and the like can now significantly reduce the maintenance costs of those reinforced concrete assets.

Sika, New Zealand’s leading supplier of concrete protection and maintenance products, recently launched two new systems that take concrete repair and protection to a whole new level. The Sika Ferrogard Patch system increases the durability of traditional concrete patch repairs by providing protection against incipient anode corrosion.

The Sika Ferrogard Duo system provides up to 50 years of reinforcement corrosion protection in chloride or carbonation contaminated concrete – without the need for regular monitoring and maintenance – and it is fully compatible with prestressed concrete structures.
The launch of these two new systems is very timely. A large proportion of New Zealand’s infrastructure is now over 50 years old and much of it is located in aggressive coastal environments. It is not surprising therefore that there is an increasing demand from asset owners for extended service lives and reduced maintenance costs of reinforced concrete.

Both Sika Ferrogard Patch and Sika Ferrogard Duo use galvanic protection to prevent reinforcement corrosion, which in turn extends asset life and reduces maintenance costs.

Although using galvanic anodes in concrete patch repair is not new, the Sika Ferrogard Patch anodes deliver improved performance and reliability over previous systems. This is partly due to their installation just outside the patch repair.

Mike Edwards, Sika New Zealand’s General Manager explains, “By placing the Sika Ferrogard Patch anodes outside the repair, they are closer to the area where corrosion is most likely to occur and are therefore more effective at preventing corrosion initiation. This external placement means we can also use a higher specification repair mortar for the patch repair, further improving repair durability. The repair mortar can also be spray applied without risking damage to the anodes.”

The improved reliability over previous systems is reinforced by the Sika Ferrogard Patch system being active without the traditional requirement to pre-soak the anodes in water, therefore eliminating one critical installation step that is frequently overlooked in anode installation. This also means the anodes are immediately active when installed, irrespective of whether the contractor has completed the patch repair.

The Sika Ferrogard Duo system, used for targeting concrete at risk of reinforcement corrosion, is a long-term solution for protecting reinforced concrete against reinforcement corrosion.

Sika Ferrogard Duo greatly extends asset life and reduces ongoing maintenance costs to almost nothing. It is a hybrid system using discrete zinc anodes that are operated initially in a temporary impressed current corrosion protection phase before switching to galvanic protection phase.

The impressed current phase, which typically uses a 12V power supply for just two weeks, halts reinforcement corrosion and ensures the steel reinforcement is fully passivated and in a non-corrosive environment.

Once this phase is completed the power supplies are removed from the site and the anodes are connected directly to the steel reinforcement where they provide up to 50 years of galvanic protection against initiation of reinforcement corrosion – even in aggressive marine environments.

“The greatest benefit to the asset owner is that after two weeks, when the power supplies are removed from site, no further monitoring, maintenance or adjustment of the system is required, so there are no ongoing costs,” says Mr Edwards. “The whole-of-life costs of the system are therefore much lower than traditional cathodic protection systems.”

The Sika Ferrogard Duo system is also compatible with prestressed concrete structures which are generally difficult to repair. Engineers are often concerned about breaking out areas of contaminated concrete that may cause the tension to be lost and are wary of hydrogen embrittlement problems if cathodic protection is employed. The Sika Ferrogard Duo systems overcome both of these concerns and reduce the amount of concrete break out required to just that which is needed to make electrical connections to the steel reinforcement.

For more information contact Sika NZ or email info@nz.sika.com
 

Publishing Information
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