Disclosed are a mixed shrinkage reducing agent for concrete and a preparation method thereof. The mixed shrinkage reducing agent for concrete includes the following components in parts by weight: 35-45 of alkali modified diatomite, 15-22 of magnesium oxide, 13-20 of vermiculite, 8-11 of borax, 3-9 of sodium hexametaphosphate, and 7-13 of citric acid modified starch. The mixed shrinkage reducing agent for concrete according to the present application is used as an admixture to be mixed into cement for preparing concrete.

In order to provide a hydroxyapatite that can be used without reservation in the food industry, a hydroxyapatite powder is provided composed of primary particles. The median size of the primary particles from which the powder is made is >0.10 μm and the aspect ratio of the primary particles is <5. The specific surface area of the hydroxyapatite powder is ≤10 m.sup.2/g, and the bulk density is >550 g/l. Also disclosed is a method with which such a hydroxyapatite powder can be obtained.

A variety of particles forming microencapsulated thermochromic materials are provided. The particles can include a thermochromic core and a metal oxide shell encapsulating the thermochromic core. The thermochromic core can include one or both of an organic thermochromic material and an inorganic salt thermochromic material. In some aspects, the particles include a dye selected from a crystal violet lactone dye, a fluoran dye, and a combination thereof. In still further aspects, the particles include a color developer selected from a hydroxybenzoate, a 4, 4′-dihydroxydiphenyl propane, a hydroxycoumarin derivative, a lauryl gallate, and a combination thereof. In some aspects, the metal oxide shell is a TiO.sub.2 shell. The particles can be used in cements and paints and for a variety of building materials. Methods of making the particles and building materials and methods of use, for example, for removing a volatile organic carbon from a building material, are also provided.

A variety of particles forming microencapsulated thermochromic materials are provided. The particles can include a thermochromic core and a metal oxide shell encapsulating the thermochromic core. The thermochromic core can include one or both of an organic thermochromic material and an inorganic salt thermochromic material. In some aspects, the particles include a dye selected from a crystal violet lactone dye, a fluoran dye, and a combination thereof. In still further aspects, the particles include a color developer selected from a hydroxybenzoate, a 4, 4′-dihydroxydiphenyl propane, a hydroxycoumarin derivative, a lauryl gallate, and a combination thereof. In some aspects, the metal oxide shell is a TiO.sub.2 shell. The particles can be used in cements and paints and for a variety of building materials. Methods of making the particles and building materials and methods of use, for example, for removing a volatile organic carbon from a building material, are also provided.

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 premixed photoluminescent composition and related hardened form and method of forming joints for pavers or stones. The premixed photoluminescent composition comprises solid aggregates; a photoluminescent particulate component adapted to emit light when photoexcited; and a binder. When in contact with an activator, oxygen or water, the binder is adapted to harden into a water-resistant binder matrix that bonds the solid aggregates and embeds the photoluminescent particulate component. In use, the water-resistant binder matrix has a transparency allowing transmission of at least a portion of the light emitted by the photoluminescent particulate component.

A premixed photoluminescent composition and related hardened form and method of forming joints for pavers or stones. The premixed photoluminescent composition comprises solid aggregates; a photoluminescent particulate component adapted to emit light when photoexcited; and a binder. When in contact with an activator, oxygen or water, the binder is adapted to harden into a water-resistant binder matrix that bonds the solid aggregates and embeds the photoluminescent particulate component. In use, the water-resistant binder matrix has a transparency allowing transmission of at least a portion of the light emitted by the photoluminescent particulate component.

A premixed photoluminescent composition and related hardened form and method of forming joints for pavers or stones. The premixed photoluminescent composition comprises solid aggregates; a photoluminescent particulate component adapted to emit light when photoexcited; and a binder. When in contact with an activator, oxygen or water, the binder is adapted to harden into a water-resistant binder matrix that bonds the solid aggregates and embeds the photoluminescent particulate component. In use, the water-resistant binder matrix has a transparency allowing transmission of at least a portion of the light emitted by the photoluminescent particulate component.

A premixed photoluminescent composition and related hardened form and method of forming joints for pavers or stones. The premixed photoluminescent composition comprises solid aggregates; a photoluminescent particulate component adapted to emit light when photoexcited; and a binder. When in contact with an activator, oxygen or water, the binder is adapted to harden into a water-resistant binder matrix that bonds the solid aggregates and embeds the photoluminescent particulate component. In use, the water-resistant binder matrix has a transparency allowing transmission of at least a portion of the light emitted by the photoluminescent particulate component.