Global Benchmarking Program

Electrically Isolated Tendons in European Transportation Structures

Post-tensioning (PT) is a method of reinforcing concrete that has greatly improved our Nation's bridges with its ability to extend span lengths, reduce concrete cracking, connect prefabricated bridge elements, and accelerate construction. Keeping check on tendon condition is vitally important to the load-carrying capacity and durability of PT bridge structures. Currently, the PT state-of-the-practice in the U.S. does not provide the ability to remotely monitor in-service tendon condition and relies upon labor-intensive visual inspection. The Federal Highway Administration, American Association of State Highway and Transportation Officials, and National Cooperative Highway Research Program sponsored a Global Benchmarking Program study to look at electrically isolated post-tensioning systems (EIT) in Italy and Switzerland with a focus on the ability of this technology to improve post-tensioning durability.

Through multiple face-to-face meetings and field visits, the study team found that both Italy and Switzerland use EITs to provide a high level of corrosion protection and provide the ability to monitor PT tendon condition throughout a structure's intended service life. They emphasized proper installation to ensure that the EIT system provided these benefits. Team recommendations for U.S. implementation include developing EIT system prequalification testing requirements, researching details to accommodate U.S. construction and inspection practices, and developing an education and outreach program for bridge designers and constructors.