Patent ID: 7849648

Claim:
A non-combustible flooring system for construction comprising: metal screw fasteners with winged drillers; a metal frame; a horizontal shear diaphragm fastened by the fasteners to the metal frame, the horizontal shear diaphragm comprising a reinforced, lightweight, dimensionally stable cementitious panel; the cementitious panel having a density of 65 to 90 pounds per cubic foot and capable of resisting shear loads when fastened to the metal frame and comprising a continuous phase resulting from the curing of an aqueous mixture comprising, on a dry basis, 49 to 68 weight % of a blend of reactive powders, 23 to 36.1 weight % uniformly distributed lightweight filler particles, and 5 to 20 weight % uniformly distributed alkali-resistant glass fibers, and optional superplasticizer; the continuous phase being uniformly reinforced with the glass fibers and uniformly containing the lightweight filler particles, the lightweight filler particles comprising ceramic microspheres and optionally at least one member selected from the group consisting of glass microspheres, fly ash cenospheres or perlite, each on a dry basis, the lightweight filler particles having a particle specific gravity of from 0.02 to 1.00 and an average particle size of about 10 to 500 microns (micrometers), a layer of Type X fire rated gypsum wallboard attached to a side of the metal frame opposed to the shear diaphragm to form a second diaphragm, wherein the winged drillers are located above the point and below the first threads of the screw and protrude laterally from a shaft of the screw, and wherein the flooring system meets the 2 hour fire resistance test rating under ASTM E-119 (effective 2003), wherein the blend of reactive powders comprises, on a dry basis, 45 to 75 wt. % calcium sulfate alpha hemihydrate, 20 to 40 wt. % Portland cement, 0.2 to 3.5 wt. % lime, and 5 to 25 wt. % of an active pozzolan comprising silica fume, wherein the flooring system has a horizontal design shear capacity of the floor shear diaphragm of 300 to 1000 pounds per linear foot, wherein the cementitious panel has a thickness of about ½ to 1½ inches.