Method of molding aqueous settable slurries containing shredded open-cell polystyrene particles

Claim 3

The method of claim 1 wherein the foam particles serrations are saw-toothed like.

Claim 4

The method of claim 2 wherein the foam particles are formed of an acrylonitrile styrene copolymer, have a maximum dimension of no more than 3/16 of an inch and a density of no more than 0.5 pound per cubic foot and the combined density of said water and said material chosen from the group consisting of cement and gypsum is greater than water.

Claim 7

In a method of making gypsum wallboard, the improvement comprising the steps of forming lightweight expanded cellular plastic beads having a major diameter of about 1/4 to 3/4 inch and a density of about 0.2 to 0.5 lb./cu.ft., shredding said beads into lightweight fragments of a size of no more than about 3/16 inch having highly uneven, rough exterior surfaces, mixing said shredded fragments with an aqueous settable gypsum slurry, and allowing said slurry to set and dry with said fragments embedded therein.

Claim 8

In a method of making gypsum wallboard, the improvement comprising the steps of forming lightweight expanded cellular plastic beads having a major diameter of about 1/4 to 3/4 inch and a density of about 0.2 to 0.5 lb./cu.ft., shredding said beads into lightweight fragments of a size of no more than about 3/16 inch having highly uneven, rough exterior surfaces, mixing said shredded fragments with an aqueous settable gypsum slurry, and allowing said slurry to set and dry with said fragments embedded therein.

Claim 9

In a method for forming a lightweight granular structure including the steps of preparing a building material slurry devoid of slurry thickeners by mixing slurry constituents, the constituents comprising water and a substantial amount of gypsum or cement the improvements which comprises the steps of adding to said slurry in an amount sufficient to substantially reduce the density of said slurry relatively low density foam particles having a large surface area compared to volume caused by tears and serrations which provide ragged ridges and intercept a substantial number of foam cells open to the exterior, mixing the foam particles and the slurry to distribute the foam particles substantially uniformly throughout the slurry and to penetrate the foam particles with the slurry and its constituents; and thereafter solidifying the slurry whereby the particles remain substantially uniformly distributed throughout the resulting granular structure.

Claim 10

In a method for forming a lightweight granular structure including the steps of preparing a building material slurry devoid of slurry thickeners by mixing slurry constituents, the constituents comprising water and a substantial amount of gypsum or cement the improvements which comprises the steps of adding to said slurry in an amount sufficient to substantially reduce the density of said slurry relatively low density foam particles having a large surface area compared to volume caused by tears and serrations which provide ragged ridges and intercept a substantial number of foam cells open to the exterior, mixing the foam particles and the slurry to distribute the foam particles substantially uniformly throughout the slurry and to penetrate the foam particles with the slurry and its constituents; and thereafter solidifying the slurry whereby the particles remain substantially uniformly distributed throughout the resulting granular structure.