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 in the form of a cube comprising an interlocking matrix of set gypsum according to ASTM C472-93, said cube has a compressive strength as measured by ASTM C472-93 greater than or equal to the compressive strength that would result if the tetrametaphosphate was not included in the mixture.

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.

Gypsum board comprising an interlocking matrix of set gypsum formed from a mixture comprising calcium sulfate material, water and at least one tetrametaphosphate compound, wherein, when said mixture is cast in the form of a cube comprising an interlocking matrix of set gypsum according to ASTM C472-93, said cube has a compressive strength as measured by ASTM C472-93 greater than or equal to the compressive strength that would result if the tetrametaphosphate was not included in the mixture.

A composition comprising a mixture of a calcium sulfate material, water, and a tetrametaphosphate compound, wherein when said composition is cast in the 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 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, when the mixture is cast in the form of a cube comprising an interlocking matrix of set gypsum according to ASTM C472-93, the cube has a compressive strength as measured by ASTM C472-93 greater than or equal to the compressive strength that would result if the tetrametaphosphate was not included in the mixture.