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. Reinforced concrete structures fail at around 20 to 30 psi and glass at 2 to 3 psi, according to Roger Rumer, marketing leader for Public Sector Business.
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