Method of forming light weight construction sheet goods from recyclable material

A method of forming a sheet of building material comprising the steps of:

• forming an aqueous pulp slurry having a pH of about 6.5 and comprising approximately 25-35 parts by weight of washed and macerated cellulosic material, approximately 8-14 parts by weight of unmacerated cellulosic material, and approximately 35-40 parts by weight of an expanded rock powder;
• adding to the aqueous pulp slurry an aqueous emulsion containing approximately 5 parts by weight of a surfactant selected from the group consisting of stearates, oleates and palmitate;
• adjusting the pH of the aqueous pulp slurry to approximately 6.5-7 by adding an aqueous mixture containing approximately 0.5-3.0 parts by weight of aluminum sulphate and 3.0-6.0 parts by weight of magnesium sulphate;
• adding 21-50 units by weight of expanded silicates having a particle diameter of about 1/8 of an inch;
• adding approximately 8-16 units by weight of polystyrene grindings and adjusting the pH to about 7.5-8;
• draining the aqueous solution from the slurry;
• washing the remaining solid mixture with water having a pH of approximately 7-7.5;
• adding to the washed solids approximately 30 units by weight of particulate polystyrene and approximately 75 units by weight of an expanded rock particles;
• forming the solids mixture into a sheet and dewatering the sheet using a pressure of at least about 0.5-6.0 psi;
• and
• drying the dewatered sheet at about 180-200 degrees F.