An investment powder which is safer than conventional powders comprising tricalcium phosphate, and being substantially or entirely free of free silica in the respiratory portion yet providing an overall expansion at 750° C. of 1% or higher sufficient to prevent mould cracking during casting. A method of making a casting comprising forming a slurry by mixing a gypsum bonded investment powder with water, pouring the slurry into a stainless steel flask around a low melting point material model, allowing the slurry to set to define a mould, heating the mould to burn out the model and casting material into the mould wherein the stainless steel flask consists of a 400 series martensitic stainless steel.

An investment powder which is safer than conventional powders comprising tricalcium phosphate, and being substantially or entirely free of free silica in the respiratory portion yet providing an overall expansion at 750° C. of 1% or higher sufficient to prevent mould cracking during casting. A method of making a casting comprising forming a slurry by mixing a gypsum bonded investment powder with water, pouring the slurry into a stainless steel flask around a low melting point material model, allowing the slurry to set to define a mould, heating the mould to burn out the model and casting material into the mould wherein the stainless steel flask consists of a 400 series martensitic stainless steel.

A water resistant sealing material suitable as a gasket or valve seal is described. The sealing material comprises modified chemically exfoliated vermiculite (CEV) in a proportion of 30-70% w/w sealing material and a filler in a proportion of 70-30% w/w sealing material, and optionally other additives in a proportion of 0-10% w/w sealing material. The modified CEV comprises water resistance enhancing monovalent cations. The sealing material is particularly useful to provide improved water resistance in gaskets and valve seals.

A plaster composition includes a joint compound/drywall mud and from about 0.5 wt % to about 10 wt % silica (e.g., hydrophilic fumed silica). The plaster composition may be a repair composition. The repair composition may be dispensed as an aerosol using a propellant. The repair composition may be useful for repairing “popcorn” textured ceilings.

A plaster composition includes a joint compound/drywall mud and from about 0.5 wt % to about 10 wt % silica (e.g., hydrophilic fumed silica). The plaster composition may be a repair composition. The repair composition may be dispensed as an aerosol using a propellant. The repair composition may be useful for repairing “popcorn” textured ceilings.

Aqueous cementitious slurries including predominantly Type I Portland cement containing an aluminate additive. The aluminate additive is an aluminate salt other than calcium aluminate or calcium sulfoaluminate, preferably sodium aluminate. Cementitious reactive powders of the slurry include the Type I Portland cement and 0.1-10 wt. % of the aluminate additive as an accelerator. The slurries may have a set time of about 10 minutes or less. Due to the short set time, the cementitious reactive powders may facilitate cement board fabrication by continuous manufacturing processes. Methods for making cement boards may include disposing the aqueous cementitious slurry including the cementitious reactive powders in a continuous layer, preferably upon a porous support, and setting the aqueous cementitious slurry with a set time of about 10 minutes or less.

Aqueous cementitious slurries including predominantly Type I Portland cement containing an aluminate additive. The aluminate additive is an aluminate salt other than calcium aluminate or calcium sulfoaluminate, preferably sodium aluminate. Cementitious reactive powders of the slurry include the Type I Portland cement and 0.1-10 wt. % of the aluminate additive as an accelerator. The slurries may have a set time of about 10 minutes or less. Due to the short set time, the cementitious reactive powders may facilitate cement board fabrication by continuous manufacturing processes. Methods for making cement boards may include disposing the aqueous cementitious slurry including the cementitious reactive powders in a continuous layer, preferably upon a porous support, and setting the aqueous cementitious slurry with a set time of about 10 minutes or less.

Mat-faced cementitious board including: (a) a cementitious core; (b) a fibrous mat having an inner first surface facing at least one face of the cementitious core, and an outer second surface, wherein the inner first surface and the outer second surface are opposed; (c) a hydrophobic, non-setting coating resulting from applying to the outer second surface of the fibrous mat a layer of hydrophobic finish composition including: (i) about 50 to about 80 weight % non-setting, inorganic filler having a mean particle diameter of about 12 microns to about 35 microns, (ii) about 20% to about 50 weight % an aqueous dispersion of a film-forming polymer, (iii) 0% to about 30 weight % additional water; (iv) an absence of fly ash, (v) an absence of pozzolanic material, (vi) an absence of hydraulic cement, (vii) an absence of calcium sulfate hemihydrate, and (viii) an absence of calcium sulfate anhydrite.

Mat-faced cementitious board including: (a) a cementitious core; (b) a fibrous mat having an inner first surface facing at least one face of the cementitious core, and an outer second surface, wherein the inner first surface and the outer second surface are opposed; (c) a hydrophobic, non-setting coating resulting from applying to the outer second surface of the fibrous mat a layer of hydrophobic finish composition including: (i) about 50 to about 80 weight % non-setting, inorganic filler having a mean particle diameter of about 12 microns to about 35 microns, (ii) about 20% to about 50 weight % an aqueous dispersion of a film-forming polymer, (iii) 0% to about 30 weight % additional water; (iv) an absence of fly ash, (v) an absence of pozzolanic material, (vi) an absence of hydraulic cement, (vii) an absence of calcium sulfate hemihydrate, and (viii) an absence of calcium sulfate anhydrite.

A method of servicing a wellbore penetrating a subterranean formation, comprising placing a wellbore servicing fluid (WSF) into the wellbore proximate a permeable zone having an average fracture width of about W microns, wherein the WSF comprises a particulate blend and water, and wherein the particulate blend comprises (a) a type A particulate material characterized by a weight average particle size of equal to or greater than about W/3 microns, and (b) a type B particulate material characterized by a weight average particle size of less than about W/3 microns, wherein a weight ratio of the type A particulate material to the type B particulate material is from about 0.05 to about 5.