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Going a step beyond the bullet-resistant security glazing familiar in banks and taxicabs, a new type of “structural envelope” based on a special polycarbonate sheet laminate from Bayer MaterialScience LLC, Pittsburgh, is said to establish a new level of bomb-blast resistance for building structures. Patent-pending Hygard BL80 Shock-Wave Sentinel is a structural solution incorporating clear PC laminate, generally less than 2 in. thick, which is said to replace several feet of concrete while providing an open, attractive appearance. Hygard BL80 reportedly exceeds the toughest explosion-resistance standards by about 30%. In blast tests, Hygard BL80 sheet flexed over 1 ft while it absorbed peak blast pressures above 80 psi, while reinforced concrete structures fail at around 20 to 30 psi and glass at 2 to 3 psi. For comparison, a Category 5 hurricane exerts 5 to 10 psi peak wind pressure, according to Roger Rumer, marketing leader for Public Sector Business. He adds that the new structure will be useful in storm protection, too.

Hygard BL80 is based on the same high-molecular-weight PC resin used in bullet-resistant sheet, but the laminate structure is different and it is used in a brand-new structural design that includes a footer, support framework, and tie-ins to the building structure. The flexible, structural envelope “shell” of Hygard BL80 utilizes a wall of the PC laminate, supported by a structural steel frame that is tied into the building structure, and separated by 7 ft of buffer space from the outside wall of the building it protects.