Composite Structures for Immersion Applications

Project ID: 4182
Principal Investigator: Daryl Little
Research Topic: Repair and Maintenance
Funded Fiscal Years: 2016
Keywords: None

Research Question

Study to determine how to increase use of composite materials for immersed Reclamation infrastructure,
including low-risk gates, guides, stop logs, trash racks and fish screens, which have traditionally been made of
corrosion-susceptible metals such as mild steel. Modern composite materials provide improved corrosion
resistance over traditional construction materials while maintaining the high strength and load capacity necessary
for many structures.

Need and Benefit

A main goal of Reclamation is the delivery of water and power. Corrosion of immersed structures causes
extraordinary maintenance costs, and can cause loss of revenues related to water delivery and power generation.
This is a common Reclamation challenge and, to date, in many cases, the only solution is continual maintenance
of structures. The continual repair and maintenance is difficult and expensive due to the location and materials. In
addition, the complex geometries of structures such as trash racks and fish screens is often difficult to protect
using traditional corrosion mitigation techniques (coatings and cathodic protection).
Composites have many properties which make them beneficial to use in a wide variety of structures. The most
valuable property of composites is that they can be designed to have specific properties based on the
environmental service conditions and required properties of the structure. They are durable, have a high
strength-to-weight ratio, and are easy to manufacture and assemble. In general, fiber-reinforced polymer
composites have high compressive, tensile and flexural strengths, good fatigue resistance, low coefficients of
friction, and exhibit damping behavior. Composites are also resistant to corrosion and work well in fluctuating
environmental conditions. These are all properties that make composites more favorable than metals for many
structures.
Despite the apparent need and benefits, the use of composite materials as a substitute for steel in immersion
applications has not been implemented at Reclamation, in part due to a lack of familiarity with structural
composites. This study will provide the science and engineering due diligence required to advance Reclamation's
experience and practices with composite structures.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Composite Structures for Immersion Applications (final, PDF, 1.9MB)
By Daryl Little
Publication completed on September 30, 2016

Corrosion of immersed structures creates maintenance problems and expenses, causing loss of revenues related to water delivery and power generation. This is a common Reclamation problem and to date the only solution is additional and ongoing maintenance. The repair is often difficult and expensive due to material replacement and accessibility. The use of composites as a substitute for the traditional metallic materials is not standard or even typical for submerged structures due to the lack of experience and knowledge in Reclamation. Composites have specific properties including high strength-to-weight ratio, resistance to corrosion, durability, and ease of manufacturing making composites more favorable than the traditional materials.

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Last Updated: 6/22/20