Cathodic Protection in Parking Structure

Harbour Light Towers Sand Key in Florida offers panoramic and unobstructed views of Clearwater Beach and the Intracoastal Waterway. Constructed in 1974, the complex includes a 17-floor beachfront high-rise residential building with a 2-level parking garage attached and direct access to the white sand beaches of Sand Key Island.

When Hurricane Elena came through Gulf of Mexico, hovering off the coast for several days, the lower floor of the parking garage was flooded with salt water. This incident caused chloride contamination of the lower sections of the columns and other concrete elements. Another strong storm event struck eight years later, again flooding the parking garage.

Proximity to the beach and normal environmental conditions are usually enough of a factor to initiate and support the corrosion process. The massive flooding of chlorides coming from the storm added to this process by accelerating the corrosion of the steel reinforcement and caused the subsequent concrete damage to the lower portions of the columns.

Initial efforts to repair the corrosion induced damage consisted of quantification of damaged areas and standard concrete repairs. When more extensive damage became evident, the Harbour Light Towers Association began working with an engineering firm to investigate the best long-term solution for corrosion protection of the columns.

After the data was gathered, several options were evaluated. The ElectroTechCP™ EZ-Anode Galvanic Cathodic Protection System, exclusively designed by STRUCTURAL TECHNOLOGIES, was selected based on its ability to address the changes in temperature and humidity. The system delivers an optimum, long-term corrosion protection solution to the garage first level columns with an expected service life of 25 years.

Repairing the Parking Garage While in Operation

STRUCTURAL was selected to perform general concrete repairs and to install the ElectroTechCP™ EZ-Anode System working with the Corrosion Solution Builders of STRUCTURAL TECHNOLOGIES. Site preparations took place before repairs and the installation of the galvanic cathodic protection system could begin. The concrete columns were first shored to provide safety to the buildings residents and the project team while repairs took place. Delaminated concrete was chipped out to expose and clean the steel reinforcement. The exposed reinforcement was then tested for continuity and electrically connected where it was found to be discontinuous. Reference cells were installed on the five selected columns for continuous performance monitoring purposes. General repairs of the concrete were also made, as needed.

The system was attached to the exterior of concrete surfaces to stop corrosion by providing a uniform corrosion protection current to all of the affected columns. Crews attached the panels to the concrete surface by means of a trowelled-on, specially formulated mortar and mechanically anchored for a permanent installation. The panels deliver current through a galvanic process and do not require an external power supply.

Planning for the Unexpected

The destination location of Clearwater Beach posed some logistical challenges during the repair process. Along with the complex and parking garage that remained fully operational and open to the public, peak season of vacationers also had to be taken into consideration when implementing the repair work. The occupancy levels, particularly during the spring break months, fluctuated and were difficult to predict. Proper safety and traffic measures along with clean-up efforts and dust control were developed accordingly for the higher occupancy.

Coastal regions, like Clearwater Beach, often experience some of the most severe weather events. While it was difficult to predict if a storm would occur during the project, and the severity and toll it might take on the Harbour Light Towers property, proper safety planning was put into place in preparation.

STRUCTURAL developed a Hurricane Prevention Plan and responsibilities were delegated to team members in the event a storm hit. The plan details what to do when a Watch or Warning is issued, during the passage of a tropical storm or hurricane, and after a storm has passed. Florida State Building Code Guidelines were also included in the plan so that crewmembers understood what is required to secure construction materials and equipment during a storm.

Installation and Performance Monitoring

In total, 56 columns at the ground level of the parking garage were repaired in 3 months and the maintenance-free ElectroTechCP™ EZ-Anode system was installed successfully. The system self-adjusts to meet changes in temperature, humidity, and a number of other factors, delivering optimum corrosion protection to the parking structure columns at all times.

After installation completed, the system continued to be monitored quarterly by both STRUCTURAL TECHNOLOGIES and STRUCTURAL for system performance verification. Analysis of the performance data collected indicated that ElectroTechCP™ EZ-Anode system will exceed the design requirements.

Proactive and Innovative Solutions

The Harbour Light Towers Association is the first multi-family residential property owner to use the ElectroTechCP™ EZ-Anode system for protection of critical reinforced concrete elements affected by chloride induced corrosion. By taking this proactive approach and implementing a long-term, innovative solution aimed at combating and controlling corrosion, Harbour Lights will benefit from a long service life and minimal repairs for the lower portions of the parking garage structure. The immediate action taken by the Association to address the damage allowed enough time to develop a solution and implement repairs that exceeded the life expectancy requirements by 10 years.