| abstract |
Fire-resistant structures are provided having at least a 20 minute ASTM E-152 fire test rating. The structures include a core having a gypsum-containing composition and a density of at least about 60 lbs/ft, a flexural strength of at least 30 lbs (1/2 inch thick material), and a screw-holding capacity of at least about 400 lbs. The gypsum-containing composition further contains a substantially uniform distribution of solids including about 65 wt. % to about 90 wt. % set gypsum dihydrate, about 7 wt. % to about 30 wt. % paper fiber, and about 1.5 wt. % to about 35 wt. % of one or more performance boosters selected from inorganic fiber, clay, vermiculate, and binder polymer. |