U.S. Army researchers have developed a new coating for reinforcing steel that both reduces steel corrosion and improves the bond between the steel reinforcement and surrounding concrete.
The technology, by the U.S. Army Engineer Research and Development Center, “meets the problem of deteriorating infrastructure where it begins—in the reinforcing steel used in nearly all concrete construction,” the research team says.
The Center’s Geotechnical Structures Laboratory and Construction Engineering Research Laboratory have been collaborating since 2006 on the corrosion-resistant ceramic-porcelain enamel for bonding concrete to steel.
Heat Bonding and Cement
Originally developed by ERDC-GSL and advanced and applied in a field demonstration by the ERDC-CERL, the technology is a unique coating process in which alkali-resistant porcelain enamels are applied and heat bonded to structural steel components, such as reinforcing bar.
A water-reactive calcium silicate or aluminate such as Portland cement is then fused into the surface of the enamel. This coating protects the steel from rusting and yields a concrete-to-steel bond three to five times stronger than the standard bond, the Army says.
The technology has enormous implications for military readiness as well as the nation’s crumbling infrastructure components, which in coastal environments may require serious repair after only five years.
Applications for ‘Every Piece of Steel’
“Before development of this technology, no simple solution existed to the corrosion problem,” the Army said in a project summary. “Chemical additives have proven to be of very limited use. Organic polymer coatings typically decrease bond strength and can delaminate. Protective metal coatings can corrode and produce debonding.”
The porcelain bonding enamel process “could potentially be used on every piece of steel currently used in both military and civilian concrete construction, including rebar, steel fiber, welded mesh wire, and sheet metal decking for composite floors,” the Army said.
The first large-scale field application of the product occurred at the Corpus Christi Army Depot in Texas; 7,200 square feet of continuously reinforced concrete pavement was installed using the new coated steel. Completed in the fall of 2009, the road provides a smooth, sturdy surface for the Depot’s car and forklift traffic, the Army says.
The next large-scale use of the technology is in process with the Missouri Department of Transportation, which funded a three-year project to culminate in the construction of a bridge using the technology. The project is currently about half-way through its second year.
Licensing and Research
The product has been licensed, although patents are pending. In 2006, GSL (one of the developing research labs) entered into a non-exclusive research license agreement with the Porcelain Enamel Institute (PEI), the enameling industry’s trade association. That license allowed PEI to introduce the technology to the enameling industry, generating interest and inquiry.
Roesch Inc.’s 2007 non-exclusive license of the technology led to a whole new spin-off company, Pro Perma Engineered Coatings LLC, which industrialized the technology and supplied coated rebar for the Corpus Christi project.
Leading researchers on the project were Vincent Hock, Dr. Philip G. Malone, Sean Morefield and Dr. Charles A. Weiss Jr., all of ERDC; and Michael Koenigstein, of Pro Perma Engineered Coatings LLC.
“This imaginative and truly revolutionary technology has been recognized by the Federal Energy Regulatory Commission chairman and the [Department of Defense] for its great promise in saving the nation money and energy,” the Army said.
“It is the first critical step toward a far-reaching transformation that will vastly improve the integrity of our roads, bridges, and other essential structures, and that will save resources, and even lives.”