High performance non-combustible gypsum-cement compositions with enhanced water durability and thermal stability for reinforced cementitious lightweight structural cement panels

A method for providing improved fire resistance for a shear diaphragm in a building by improving resistance to thermal transmission of a structural cement panel in a building structure comprising applying a first non-combustible, fire resistant lightweight reinforced cementitious panel for resisting transverse and shear diaphragm loads having improved water durability and greater resistance to thermal transmission, to a metal framing element for use as a shear diaphragm in shear bearing wall systems, flooring systems and/or roofing system in said building,

• the first panel comprising:
• a continuous phase resulting from the curing of an aqueous mixture of:
• a cementitious composition comprising, on a dry basis,
• 50 to 95 wt % reactive powder,
• 1 to 20 wt % of coated hydrophobic expanded perlite particles uniformly distributed as lightweight filler in said continuous phase, the coated hydrophobic perlite particles having a diameter in the range of about 1 to 500 microns (micrometers), a median diameter of 20 to 150 microns (micrometers) and an effective particle density (specific gravity) of less than about 0.50 g/cc,
• 0 to 25 wt % hollow ceramic microspheres, and
• 3 to 16 wt. % alkali-resistant glass fibers for uniformly reinforcing the continuous phase;
• wherein said reactive powder comprises:
• 25 to 75 wt. % calcium sulfate alpha hemihydrate,
• 10 to 75 wt. % hydraulic cement comprising Portland cement,
• 0 to 3.5 wt. % lime, and
• 5 to 30 wt. % of an active pozzolan;
• and
• the first panel having a density of 50 to 100 pounds per cubic foot;
• wherein a time for thermal transmission in the first panel is delayed by about 10% % to 40% compared to a time for thermal transmission in a second panel having the same composition as the first panel except for comprising ceramic microspheres instead of coated hydrophobic expanded perlite particles.