Gypsum-containing composition having enhanced resistance to permanent deformation

A composition comprising a mixture of host particles having accessible voids therein;

• calcium sulfate material, at least a portion of which is in the form of crystals in and about the voids of the host particles;
• and a tetrametaphosphate compound, wherein when said composition is cast to form a ½ inch board comprising an interlocking matrix of set gypsum, said board has a sag resistance, as determined according to ASTM C473-95, of less than about 0.1 inch per two foot length of said board.

A composition useful, when mixed with water, for producing a machinable set gypsum-containing product, comprising a mixture of a starch, particles of a water-redispersible polymer, calcium sulfate material, and a tetrametaphosphate compound.

A composition useful, when mixed with water, for finishing joints between edges of gypsum boards, comprising a mixture of a binder, a thickener, a non-leveling agent, calcium sulfate material, and a tetrametaphosphate compound.

A composition, useful for producing an acoustical tile, comprising a mixture of a gelatinized starch, a mineral wool, a calcium sulfate material, water, and a tetrametaphosphate compound.

A composition, useful for producing an acoustical tile, comprising a mixture of a gelatinized starch, expanded perlite particles, a fiber reinforcing agent, a calcium sulfate material, water, and a tetrametaphosphate compound.

A composition, useful for producing a gypsum board, comprising a mixture of a calcium sulfate material, water, an accelerator, and a tetrametaphosphate compound.

A composition comprising a mixture of a calcium sulfate material, water, and a tetrametaphosphate compound, wherein when said composition is used to prepare a product comprising an interlocking matrix of set gypsum, said product has greater strength than it would have if the tetrametaphosphate compound had not been included in the mixture.

A method for producing a set gypsum-containing product having increased resistance to permanent deformation, comprising:

• forming a mixture of a calcium sulfate material, water, and a tetrametaphosphate compound, and
• maintaining the mixture under conditions sufficient for the calcium sulfate material to form an interlocking matrix of set gypsum material,
• the tetrametaphosphate compound having been included in the mixture in an amount such that the set gypsum-containing product has greater resistance to permanent deformation than it would have if the tetrametaphosphate compound had not been included in the mixture.

A method for producing a set gypsum-containing product having enhanced strength, comprising:

• forming a mixture of a calcium sulfate material, water, and a tetrametaphosphate compound, and
• maintaining the mixture under conditions sufficient for the calcium sulfate material to form an interlocking matrix of set gypsum material,
• the tetrametaphosphate compound having been included in the mixture in an amount such that the set gypsum-containing product has greater strength than it would have if the tetrametaphosphate compound had not been included in the mixture.

Gypsum board comprising an interlocking matrix of set gypsum formed from at least calcined gypsum, water and at least one tetrametaphosphate compound, said gypsum board having a sag resistance, as determined according to ASTM C473-95, of less than about 0.1 inch per two foot length of said board.

A gypsum board comprising a core of material sandwiched between cover sheets, wherein the core comprises an interlocking matrix of set gypsum, said board having been prepared by a method comprising:

• forming or depositing a mixture between the cover sheets, wherein the mixture comprises a calcium sulfate material, water, and one or more tetrametaphosphate compounds, and
• maintaining the mixture under conditions sufficient for the calcium sulfate material to form the interlocking matrix of set gypsum,
• the tetrametaphosphate compound having been included in the mixture in an amount such that the gypsum board has a sag resistance, as determined according to ASTM C473-95, of less than about 0.1 inch per two-foot length of said board.