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Publication Number: FHWA-HRT-11-063
Date: August 2011

 

Nano-Enhanced Repair Materials: Pursuing A Superior Coating for Corrosion Prevention

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Exploratory Advanced Research . . . Next Generation Transportation Solutions

Corrosion of highway bridges has been estimated to cost the Nation $8.29 billion annually.1 A corrosion-inhibiting nanocomposite solution that can be used to repair, strengthen, and protect highway infrastructure is the goal of "Multifunctional Nanomaterials and Processes for Infrastructure Repair and Corrosion Inhibition," an Exploratory Advanced Research (EAR) Program project awarded to Florida State University by the Federal Highway Administration (FHWA).

Addressing A Compelling Need

Photo. A closeup of cracked and spalled concrete at the foot of a bridge pier just above the water level (Herbert C. Bonner Bridge, Dare County, North Carolina).

Photo credit, © North Carolina Department of Transportation

Much of the Nation's infrastructure is reaching the end of its useful life at a time when resources for repair and replacement are severely constrained. With so many critical highway structures in need of rehabilitation, an urgent search for more effective repair methods and longer lasting repair materials to preserve them is underway. In this 2-year EAR Program project, researchers are developing a promising multifunctional repair material to protect and strengthen salt-contaminated, corroding bridges. The experimental material utilizes carbon nanotubes (CNTs), which offer superior strength and thermal conductivity. The aim is to harness these properties in a coating that will inhibit corrosion and add strength to structural members.

Optimizing the Mixture Design

This project is distinctive in its pursuit of a self-curing, spray-on coating that can be easily applied at the repair site, lowering labor costs. High concentrations of nanoparticles, well-dispersed in a composite matrix, could provide a protective barrier against corrosion while strengthening the structure. The challenge to researchers has been to identify the optimal combination of matrix system, curing agent, and CNT concentration that will result in high strength, durability, and ease of application at a moderate cost.

Exploratory Challenges

Several aspects of the study's technical approach involve considerable risk:

A new SprayWriter is shown on a table surrounded by various components (manual, plastic tubing, metallic hose with brass fitting, other attachments) wrapped in plastic. The equipment appears to be about 3 ft high on a base of approximately 4 to 6 sq ft. Part of the unit is labeled FISNAR VC-1195A. Visible parts of the equipment include three dials, switches, a hose, a power cord, and others. Some structural components appear to be made of stainless steel.

SprayWriter, for applying the repair material. © 2011 Florida State University. All rights reserved.

Durability and Physical Properties

To assess the composite coating's behavior and performance for reducing corrosion and repair of infrastructure, the following will be evaluated:

These tests will be carried out at ambient as well as at elevated temperatures and humidity levels.

Looking Ahead

The technical innovations developed by the research team could significantly advance multifunctional composite coating for corrosion control as well as strengthening and repair of infrastructure. At the conclusion of the project, FHWA will assess the feasibility of next steps, including field testing to test the corrosion-inhibition properties of the materials as well as their potential for strengthening bridges

"A multifunctional nanomaterial that is corrosion-resistant, durable, and cost effective could substantially reduce the life-cycle cost of bridges and other highway structures," says Paul Virmani of FHWA, "and would have potential applications beyond the highway industry, both to protect new structures and to extend the lives of older ones." Besides bridges, corrosion is a major problem in military applications, drinking water and sewer systems, gas and other transmission pipelines, hazardous materials storage, and many other areas that might benefit with improved service life.

Learn More

For more information on this EAR Program project, contact Paul Virmani, Ph.D., FHWA Office of Infrastructure Research and Development, at 202-493-3052 (email: paul.virmani@dot.gov).

What Is the Exploratory Advanced Research Program?

FHWA's Exploratory Advanced Research (EAR) Program focuses on long-term, high-risk research with a high payoff potential. The program addresses underlying gaps faced by applied highway research programs, anticipates emerging issues with national implications, and reflects broad transportation industry goals and objectives.

To learn more about the EAR Program, visit the Exploratory Advanced Research Web site at www.fhwa.dot.gov/advancedresearch. The site features information on research solicitations, updates on ongoing research, links to published materials, summaries of past EAR Program events, and details on upcoming events. For additional information, contact David Kuehn at FHWA, 202-493-3414 (email: david.kuehn@dot.gov), or Terry Halkyard at FHWA, 202-493-3467 (email: terry.halkyard@dot.gov).

1 M. Yunovich, N. G. Thompson, and Y. P. Virmani. Corrosion protection system for construction and rehabilitation of reinforced concrete bridges. International Journal of Materials and Product Technology, Vol. 23, Nos. 3-4, pp. 269-285, 2005.

 

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