Exploratory Advanced Research . . . Next Generation Transportation Solutions

Optimizing the Mixture Design

This project is distinctive in its pursuit of a selfcuring, 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:

•	 Nanoparticle dispersion—Nanoparticles tend 

to clump, and hence achieving a uniform 

coating layer is difficult. The research has pursued a sonication and other mixing technologies that can deliver both a high concentration and uniform distribution of the CNTs in 

an epoxy coating. The study has achieved 

well-dispersed concentrations of 4 percent 

CNTs, with higher concentrations expected.

•	 Curing behavior—CNTs have been shown to 

interfere with epoxy curing in ways that are 

not well understood, causing undercuring, 

which could result in premature failure due to 

poor adhesion, delamination, microcracking, 

and reduced tensile and flexural strength. 

The study is expanding the knowledge of 

these processes as it experiments with mix 

reformulations with different concentrations 

of CNTs and different curing conditions. 

•	 Adhesion—The investigators have devised a 

process to spray the composite repair material 

in a liquid form that will adhere permanently 

to structures under repair, allowing in situ 

application, which reduces the time and 

costs required for repairs over conventional 

repair techniques. Scaling up the spray application technology is the next challenge. 

The Exploratory Advanced Research Program Fact Sheet

Addressing A Compelling Need

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 saltcontaminated, 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. 

Corrosion of highway bridges has 

been estimated to cost the Nation 

$8.29 billion annually.1

 A corrosioninhibiting 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).

Nano-Enhanced Repair Materials 

Pursuing a Superior Coating for Corrosion Prevention

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.
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:

•	 Thermal mechanical characterization by dynamic and thermal analysis (dynamic mechanical rheological testing data can be used to 

predict long-term performance through analysis of the material’s chemical makeup). 

•	 Corrosion behavior with electrochemical impedance spectroscopy (useful for identifying 

possible limitations and defects in the protective coating during its exposure to corrosive 

environments).

•	 Adhesion strength by peeling/shearing test.

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.

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@fhwa.dot.gov), or 

Terry Halkyard at FHWA, 202-493-3467 

(email: terry.halkyard@fhwa.dot.gov).

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).

Publication No. 

FHWA-HRT-11-063

HRTM-04/08-11(1M)E

Nano-Enhanced Repair Materials 

Pursuing a Superior Coating for Corrosion Prevention

Photo credit, page 1: 

© North Carolina Department 

of Transportation

SprayWriter, for applying 

the repair material. © 2011 

Florida State University. 

All rights reserved.