A sizing composition including water, a polyvinylpyrrolidone film former, a silane coupling agent, a lubricant, and a surfactant is provided. The polyvinylpyrrolidone film former constitutes from 30 wt. % to 50 wt. % of the dry solids of the sizing composition. Wet use chopped strand glass fibers for use in reinforcing gypsum board are also provided. The wet use chopped strand glass fibers include chopped glass fibers having the sizing composition applied thereto. The sizing composition improves fiber bundle integrity, fiber flow rate, fiber flow rate consistency, and dispersibility of the wet use chopped strand glass fibers in a gypsum matrix or slurry.

A calcined gypsum treatment apparatus has an agitating type of cooler provided with a cooling region for cooling the calcined gypsum, and a moisture supplying device for incorporating moisture into the calcined gypsum. The moisture supplying device includes a humid gas-feeding port which introduces humid gas including moisture or steam, directly into the cooling region. The calcined gypsum is introduced through a calcined gypsum introduction port into the cooling region, and the moisture is incorporated into the calcined gypsum to modify the calcined gypsum. The humid gas-feeding port is positioned in vicinity to the calcined gypsum introduction port so as to allow the spouted or delivered flow of the humid gas to be brought into contact with the calcined gypsum immediately after introduced into the cooling region.

A method of producing a supplementary cementitious material, includes providing at least one waste material selected from quarry sludge, aggregate washing sludge and road cleaning sludge, removing excess water from said waste material so as to provide a dry waste material, and either: mixing the dry waste material with a source of calcium sulphate to obtain a raw material mixture, and calcining the raw material mixture at a temperature of 700-900 C. to obtain the supplementary cementitious material, or: calcining the dry waste material at a temperature of 700-900 C. to obtain a calcined waste material, and mixing the calcined waste material with a calcined source of calcium sulphate to obtain the supplementary cementitious material.

A process is provided for creating a gypsum wallboard slurry with enhanced strength. The process includes providing a gypsum wallboard slurry mixer, providing suitable amounts of calcined gypsum and water in the mixer to create a slurry, agitating the slurry in the mixer, extracting a portion of the slurry in the mixer, reintroducing the extracted portion into the mixer for further mixing, and dispensing the mixed slurry from an outlet of the mixer.

A process is provided for creating a gypsum wallboard slurry with enhanced strength. The process includes providing a gypsum wallboard slurry mixer, providing suitable amounts of calcined gypsum and water in the mixer to create a slurry, agitating the slurry in the mixer, extracting a portion of the slurry in the mixer, reintroducing the extracted portion into the mixer for further mixing, and dispensing the mixed slurry from an outlet of the mixer.

The invention relates to a plaster-based composition comprising nanometric boehmite and/or nanometric aluminium trihydroxide, this composition making it possible to obtain products having better dimensional stability at high and in particular at very high temperature. The invention also relates to the method of obtaining the products, and the products produced.

The invention relates to a plaster-based composition comprising nanometric boehmite and/or nanometric aluminium trihydroxide, this composition making it possible to obtain products having better dimensional stability at high and in particular at very high temperature. The invention also relates to the method of obtaining the products, and the products produced.

A dental gypsum slurry includes water and a dental gypsum powder containing hemihydrate gypsum and a polycarboxylic acid salt-based water-reducing agent, wherein a powder-water ratio of the water to the dental gypsum powder is 0.24 to 0.50, and when the water and the dental gypsum powder being mixed are poured up to a height of 50 mm in a cylindrical mold having an inner diameter of 35 mm, which is vertically placed on a flat surface, and then, the cylindrical mold is pulled upward at 10 mm/s at 30 seconds after start of mixing so that a mixture spreads planarly, the diameter of the mixture is 141.4 mm or more.

An embodiment according to the present invention provides a dental gypsum powder including a hemihydrate gypsum and a water-reducing agent, wherein the mass ratio of the water-reducing agent to the hemihydrate gypsum is 0.1 to 1%, the content of particles having a particle diameter of 10 m or less is 15 to 35 volume %, the content of particles having a particle diameter of 20 m or less is 40 to 55 volume %, and the content of particles having a particle diameter of 30 m or less is 55 to 75 volume %.

Aspects of the invention include a method of producing a cement material comprising step of: first reacting a calcium-bearing starting material with a first acid to produce an aqueous first calcium salt; second reacting the aqueous first calcium salt with a second acid to produce a solid second calcium salt; wherein the second acid is different from the first acid and the second calcium salt is different from the first calcium salt; and thermally treating the second calcium salt to produce a first cement material. Preferably, but not necessarily, during the second reacting step, reaction between the first calcium salt and the second acid regenerates the first acid.