Patent ID: 6406755
Filing Date: 2002-06-18
Classification: C04B,C09K,Y02W

Abstract:
A method for modifying the spray-application of gypsum-containing fireproofing comprising:(a) spray-applying through a mixer and hose a first fireproofing composition slurry, said slurry comprising: a gypsum binder in the amount of 25-95% based on total dry solids in the fireproofing composition; at least one lightweight aggregate having a bulk density of 0.4-10 pounds per cubic foot, said at least one lightweight aggregate comprising expanded vermiculite, expanded perlite, expanded clay prills, glass beads, mineral wool, shredded paper, shredded expanded polystyrene, or mixture thereof, said at least one lightweight aggregate being present in an amount of 1-80% based on dry weight of solids in the fireproofing composition; an air entraining agent operative to entrain air of a stable nature in the composition; and a proteinaceous set retarding agent derived from animal byproduct, said proteinaceous set retarding agent being present in said first fireproofing composition in an amount not exceeding 0.4% by dry weight based on the amount of gypsum binder; and (b) subsequently introducing into the same mixer and same hose a second fireproofing composition slurry, said slurry comprising: a gypsum binder in the amount of 25-95% based on total dry solids in said second fireproofing composition slurry; at least one lightweight aggregate having a bulk density of 0.4-10 pounds per cubic foot, said at least one lightweight aggregate comprising expanded vermiculite, expanded perlite, expanded clay prills, glass beads, mineral wool, shredded paper, shredded expanded Polystyrene, or mixture thereof, said at least one lightweight aggregate being present in an amount of 1-80% based on dry weight of solids in said second fireproofing composition slurry; an air entraining agent operative to entrain air of a stable nature in said second fireproofing composition slurry; a synthetic set retarding agent present in said second fireproofing composition slurry in an amount operative, at spray application temperatures of 35Â°-150Â° F., to delay setting of said slurry for at least 24 hours, said synthetic set retarding agent comprising polyacrylic acid or a salt or derivative thereof in the amount of 0.1-4.5% or a phosphoric acid or salt or derivative thereof in the amount of 0.2-9.0%, all percentages based on dry weight of said binder in said second fireproofing composition slurry, and said synthetic set retarding agent having a molecular weight between 1000-15,000.