April 27, 2007

JOCELYN AUGUSTINO/ FEMA

As the U.S. Pentagon rebuilds, officials are employing new techniques and materials which will better protect its occupants.

Innovation

Polymer spray protects building occupants

Liner material gets new life protecting people from bombs

PETER KENTER

correspondent

A polymer material that started life as a tough coating to protect truck-beds is now protecting soldiers and government buildings as well.

Because of its reputation for toughness, LINE-X, a spray-on material invented in the U.S., was gradually tested on broader applications, including military armour and government buildings.

“The U.S. Department of Defense selected LINE-X proprietary bomb blast coating application for the renovation of the Pentagon after 9/11 in the event of another terrorist attack,” says Cam Tomalty, one of the owners of LINE-X Canada, the Canadian distributor of the product, with headquarters in Red Deer, Alberta.

The architectural product, dubbed Paxcon, isn’t intended to protect buildings themselves from bomb blasts. “One of the greatest threats to building occupants during a bomb blast isn’t the blast itself,” says Tomalty. “It’s the fragmentation of building materials, fixtures and windows that results in the deaths of people inside the building.”

Retrofitting existing unreinforced concrete masonry unit walls with the spray-on polymer takes advantage of the toughness and resiliency of the material to absorb and dissipate blast energy. Under force, the product will stretch up to 700 per cent. Bricks and other construction materials are bound together, to maintain the structural integrity of a building long enough for occupants to escape before an imminent collapse.

“Although sprayed walls may shatter in a blast, the elastomeric material remains intact and contains the debris, limiting fragmentation by nearly 50 per cent,” says Tomalty.

Tests conducted by the Air Force Research Laboratory and the U.S. Army Corps. of Engineers at New Mexico Tech’s Energetic Materials Research and Testing Center near Socorro, New Mexico, confirmed that the polymer coating actually prevents concrete from breaking apart in an explosion. The tests consisted of detonating more than 200 lbs. (91 kg) of TNT and 4 lbs. (2 kg) of C-4 Plastic Explosives at a stand-off distance of approximately 30 feet (9 metres). The room protected with Paxcon remained virtually intact and test results indicated an occupant would have survived the blast.

To date, the product has been used to reinforce the Washington Naval Yard near Washington DC, a National Guard facility in Niagara Falls, NY, a federal government building in downtown Manhattan, NY, and the British Ministry of Defense building in London, among others. The product has also been used at Canadian government locations, although the contracts specify that the exact locations of the projects can not be revealed.

“We applied the product at a mail sorting room at a military base in British Columbia,” says Tomalty. “In this case, we sprayed the inside of the room, because that’s where mail sorting occurs and packages are sent through the x-ray machine for inspection. Any bomb blast would occur inside the facility.”

The mail room was a new project, so the material was applied to the inside surfaces of the building’s brick exterior and again to the drywall inside the building.

The product is also being used in such applications as meat packing plants, to prevent bacteria from entering cracks in walls and floors.

Tests are under way for further applications including the protection of buildings that might suffer fragmentation during earthquakes, tornadoes or hurricanes.

“Applying the material costs about $10 to $20 per square foot, depending on the application,” says Tomalty.

“And not only does it protect against fragmentation — we can also colour match it. The exterior surface of the Pentagon looks just the same as it did before the coating was applied.”

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