DP-91 Cathodic Protection (CP) for Reinforced Concrete Structures
The Salt of the Earth

In certain areas of the country, salt intruding into the concrete is deteriorating bridge structures. This causes spalling as the reinforcing steel corrodes. Salt can come from either deicing operations or from coastal environments. Protection systems and design criteria are available that will inhibit corrosion and concrete deterioration in new structures.

However, existing structures that are already with contaminated salt are very difficult to handle. Often, with the only choices available are to continue patching spalls or to replace the entire structure. Cathodic protection (CP) for structures is a cost-effective alternative to replacement and other types of rehabilitation methods. Extending this type of protection to vertical surfaces (such as pier columns and faces of pier caps) has been a challenge. This process involves fastening the anode system to a vertical surface, thus working against the force of gravity.

The Office of Technology Applications has worked closely with the private sector, other FHWA offices, and State highway research personnel in modifying anodes for use on vertical surfaces. CP has been successfully applied to substructure units in a variety of forms. Projects with different anodes were used on pilot projects in several States. Owners are also advised that CP can only be as effective as their commitment to maintain it once systems are installed.

DP-91 was established to package and promote CP applications for reinforced concrete structures and to develop solutions to certain problems. This demonstration project provides technical assistance and seed money for construction and evaluation. Acontinuous evaluation of the complete system of installing CP is performed to update the state of the art of CP on structures. This project also provides training to the users of CP to protect their structures and demonstrates several products developed under the Strategic Highway Research Program (SHRP), as well as the results of the LongTerm Pavement Performance Program report.

Several pilot projects are underway with a variety of anodes being evaluated. Prior evaluation of the systems and extended coordination with the CP industry took place during 1994. Pilot projects in several States are being evaluated. Information from these projects will be used to more efficiently install CP on substructures. Also, FHWA maintains close coordination with the CP industry to overcome the shortage of anode supply companies. An "International Conference on Corrosion and Cathodic Protection" will be held in December 1998 in Florida.

Telephone assistance is available from the project manager. Financial assistance in the form of "seed money" may also be available.

U.S. Department of Transportation
Federal Highway Administration


Project Manager
Donald Jackson
(202) 366-6770