CassetteTM – Surface Mounted Ribbon Anode System

August 17, 2018
jubilee bridge

CassetteTM is a scalable mesh ribbon impressed current cathodic protection (ICCP) system for the protection of concrete structures affected by corrosion of the reinforcing. CassetteTM is mounted on the surface of the concrete, eliminating the need for excavation and burial typically required for conventional embeddable anodes. CassetteTM is best suited for use where there is limited access or wet conditions. CassetteTM is rapidly installed with minimal excavation, limited to anchoring and establishing ground connections to the reinforcing steel. This results in sizeable cost reductions from conventional anode installations. Its simplicity eliminates the need for highly qualified installation crews adding to the already significant cost savings for the project. Used in combination with the Camur IITM power supply and monitoring system, CassetteTM will effectively mitigate corrosion and extend the service life of reinforced concrete structures.

CassetteTM consists of a fiberglass H-shape profile loaded with a titanium ribbon on a conductive felt (Figure 1). The system is attached to the concrete using stainless steel or fiberglass anchors. The ribbon mesh anode is sandwiched between the felt and the fiberglass profile, so the anode element resides outside of the concrete. The felt is made conductive by application of a hygroscopic gel when used in dry environments or by the seawater in splash zones. All components of the system are resistant to corrosion and hence the system can be used in corrosive environments such marine, industrial and urban locations.

Function

CassetteTM protects the steel reinforcing in concrete employing cathodic protection by impressed current. A current is passed between the titanium mesh and the reinforcement to eliminate the corrosion process on the reinforcement.

In highly chloride contaminated structures, the requirement for protective current is relatively high. In these cases, galvanic anodes may not be sufficient to provide adequate protection. CassetteTM allows the designer to deliver sufficient current to effectively protect the steel in these conditions. Cassette output is not limited by the anode characteristics, as is the case with galvanic systems. In addition, CassetteTM can be supplied with double ribbon anodes (Figure 2). This allows high flexibility for design and operation of the ICCP system.

In addition to its use for exposed concrete structures, CassetteTM can be used in restricted or confined spaces because it is:

  • Located on the surface of the concrete and hence there is very little preparation work required.
  • Prefabricated and can be rapidly deployed and installed with minimal disruption.

Conventional ICCP installations run the risk of short circuits caused when the anode contacts the reinforcing steel. The risk is increased when the reinforcing is shallow.
 CassetteTM eliminates this risk as the ribbon anode is placed away from the concrete surface.

CassetteTM eliminates the risk of “current dumping”. This occurs when an embedded anode encounters an area of extreme low resistivity, typically caused by wetness in the concrete, resulting in considerable imbalance in current output. CassetteTM encapsulates the ribbon anode in an impregnated felt providing a uniform environment surrounding the ribbon anode.

Because CassetteTM is scalable and is installed in sections, this makes it easy to replace, if needed. Single CassetteTM sections can be removed and replaced with minimal effort and at low cost, as opposed to conventional embedded anodes, which would require an invasive procedure with excavation and concrete repair.

Benefits

CassetteTM delivers cathodic protection current with a mixed metal oxide coated titanium mesh mounted away from the surface of the concrete. This eliminates the risk of acidification, the creation of acidic conditions at the interface of the anode and the concrete, a cause for failure of embeddable impressed current anodes in wet concrete structures.

CassetteTM was first used in 2002 on a marine structure in Norway. That system is still in place and fully operational today. Upon it’s first use in the U.K. CassetteTM won a prize for innovation after its installation on the Silver Jubilee Bridge, Merseyside, England.

NoCo specializes in providing state-of-the-art corrosion protection solutions for concrete structures. We can tailor scalable systems with the goal of extending the service life of concrete assets at a fraction of the cost of repair and replace. Should you have any further questions, please do not hesitate to contact us.