Abstract

Reinforced concrete bridges and other maritime infrastructure are at high risk for corrosion related damage over its service life. These assets are subjected to harsh exposures that will degrade ordinary protective measures for reinforced concrete over time. Sacrificial (galvanic) cathodic protection (CP) systems have been used successfully to protect bridge and other reinforced concrete infrastructure in Texas for approximately 30 years. As these systems age, owners are faced with decisions regarding timing and need to replace existing CP systems. This paper will present case studies from recent testing of sacrificial CP systems from several infrastructure projects along the Texas gulf coast, with ages up to 25 years old. Results from testing indicate many of the CP systems are still offering some level of cathodic protection. Considerations and options for continued monitoring, maintenance and repair, or replacement of the CP systems are presented.

Introduction

Managing aging reinforced concrete infrastructure is a complex and capital-intensive task, particularly in harsh marine and coastal environments. Corrosion from saltwater, coupled with wet and dry cycles, are particularly problematic for long-term durability of reinforced concrete. The Gulf Coast presents a challenge for maintaining service life of concrete structures that are exposed to high levels of chlorides, either by direct contact with salty or brackish water or by indirect contact with salt spray. Chlorides induce corrosion of the steel reinforcement which initiates cracking and spalling of the concrete, reducing the service life of the structure. If left unmitigated, corrosion can result in section loss of the reinforcement and can create a potential for compromised strength and safety concerns. Sacrificial (galvanic) cathodic protection (CP) systems are used to extend the service life of reinforced structures subject to harsh exposures such as bridges, ports, and other infrastructure. These systems have been used to protect bridge and other reinforced concrete infrastructure in Texas for nearly 30 years.1 As these systems age, owners are faced with decisions regarding timing and need to replace existing CP systems. This paper will present case studies from recent testing of sacrificial CP systems from four different infrastructure projects along the Texas gulf coast. General considerations and options for continued monitoring, maintenance and repair, or replacement of the CP systems are also presented.

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