Second, the reinforcing steel is checked to confirm electrical continuity. This is not a complex operation and requires only a voltage meter, some modest training and access to the reinforcing steel. Should areas of discontinuity be found, these are usually easily addressed using a variety of methods e.g. bonding a wire between the discontinuous rebar or utilizing a weld pencil rod (Number 2 rebar) to lay and imbed where needed.
Before the cleaning and re-pour process is started, provisions are made to route the system wires inside walls and along the building to their respective junction box and rectifier. This can be done using caulk joints in the concrete or by running the wire in a conduit. With a modest amount of effort, the wiring can be hidden without adversely affecting the systems integrity or adding a lot of cost. Having completed the reference electrode installation, testing for electrical continuity and making provisions for the routing of cable and wiring, the appropriate concrete repairs can be completed.
Once the concrete repairs are completed, the next step is to check for any exposed steel that might have insufficient concrete coverage or isolated reinforcing steel protruding out of the concrete. This is a critical step because direct contact between the anode/conductive coating and the reinforcing steel will create a short-circuit and prevent the system from operating properly. A jeeper is used to find any exposed steel -- this is a simple inspection process which quickly identifies any exposed steel. Once identified, the exposed steel is coated with a non-conductive epoxy, isolating the steel from the CP system.
After making provisions for wiring and completing the concrete restorations, including adequate curing time, the CP system installation begins in earnest. The first step is to lay down the anode wires using a mesh tape and then covering with the conductive mastic.
Once that is completed, the conductive coating is applied over the entire surface. The conductive coating system is a proprietary paint formulation that is applied to the concrete surface at thickness of approximately 10 DFT. As with any coating system, proper care must be given to surface preparation, application temperature and humidity, surface dryness and curing time. The conductive mastic coating requires the same care and diligence that any contractor would expect of typical concrete coatings. After the conductive coating has been applied, a variety of top coats or overlays (including tile) can be installed depending on the owner’s aesthetic requirements.
A little electrical work to mount junction boxes and rectifiers, completing the cabling installations and making the appropriate wire terminations completes the project. A NACE certified technician commissions and tests the system once the contractor has completed the project.
Contractors have an opportunity to provide value added service to their clients through the application of cathodic protection. Because cathodic protection will prevent future corrosion, clients are satisfied for the long term, which will help to build referrals for future work. Experienced concrete contractors can add cathodic protection installation to their services with minimal investment of time for training. The installation tasks include continuity testing, basic electrical wiring, and painting -- all of which can be easily performed by a concrete contractor with only a modest amount of training.
Ted Huck is Vice President of Sales and Marketing for MATCOR, Inc., headquartered in Pennsylvania. He holds a BS in Electrical Engineering and a Masters in Business Administration. He has worked with clients worldwide on cathodic protection applications in power plants, condominiums, parking garages, above ground storage tanks and more. Ted can be reached at firstname.lastname@example.org or www.matcor.com