A joint development effort led by Sherwin-Williams—involving B&H Coatings, Inc., Teijin Twaron USA, Inc. and TechFab LLC— has created patent-pending construction technology that can be used to more easily and cost-effectively build blast-resistant structures and retrofit existing structure, and in doing so, help protect people against terror attacks.
The technology uses pre-fabricated reinforced polyurea panels that elongate and stretch and act as a safety net to contain blast pressure and flying debris.
Sherwin-Williams’ General Polymers business unit, based in Cincinnati, OH, provided the polyurea coating used in the panels. The polyurea elastomer has balanced elongation, flexibility and tensile strength properties which allow the coating to expand and stretch like a balloon that will not break, even when subjected to high levels of blast pressure and flying debris.
“The concept is to catch the explosive force on the inner side of the structure, and to protect life within against flying debris and collateral damage,” said John Durig, director of Sherwin-Williams’ General Polymers business unit. Speaking on behalf of the consortium involved in the development effort, Durig added, “We fully expect the technology to be useful for the protection of embassies, military installations, waterworks, nuclear plants—any place that might be subject to a terrorist attack.”
Prefabricated reinforced polyurea panels require less material, are easier to install and less expensive to use.
“Blast-resistant panels allow the coating—the critical element for blast-resistance—to be shop-applied rather than sprayed-in-place,” Durig said. “The technology also may contribute to preventing progressive collapse.”
Spraying polyurea at the construction site can result in quality control problems and it requires the use of expensive application equipment, specially-trained applicators, ventilation, isolation of the installation areas and respiratory equipment.
“The use of panels eliminates these issues,” Durig said.
Sherwin-Williams signed an agreement last August with the U.S. Department of Defense to conduct blast testing on the panels. In three sets of tests at the U.S. Army Aberdeen Test Center at the Department of Defense’s Aberdeen Proving Ground in Hartford County, MD, panel variations were subjected to blasts created by 70 pounds of C-4 explosives at a distance of 30 feet. A third round of blast testing is planned.
Tests–which were invented and conducted by Bruce S. Hall of B&H Coatings, Inc.—also showed that the panels demonstrated ballistic performance. The technology also meets ASTM E-84 requirements for a Class A fire-rating.
Tests on polyurea coatings performed in the late 1990s under the direction of Los Alamos Technical Associates, Inc. demonstrated that nuclear contamination can be mitigated with a single water rinse, and that the polyurea coating is radiation resistant.
The Israeli government and Turkish military already have expressed interest in the technology, according to Durig.
B&H Coatings is a Salisbury, MD coatings contracting firm specializing in the application of polyurea.