A chemical additive for calcium sulphoaluminate-modified Portland cement comprises the following substances: (a) at least one alkanolamine borate; (b) at least one organic alcohol; and (c) at least one saccharide or a derivative thereof; and the substances and water are sequentially mixed and stirred to obtain the chemical additive for calcium sulphoaluminate-modified Portland cement. The chemical additive for calcium sulphoaluminate-modified Portland cement provided by the invention has better effects of regulating the setting time of the calcium sulphoaluminate-modified Portland cement and improving the 3d/28d strength increase rate, and also has a grinding aid effect when being added during grinding.

Precipitated particles may be formed under conditions that provide a particle morphology suitable for conveying a desired set of properties to a wellbore circulation fluid. Methods for using precipitated particles in a wellbore may comprise: selecting precipitation conditions for producing precipitated particles that are substantially non-spherical in shape, are about 1 micron or under in size, or any combination thereof; forming the precipitated particles from a reaction mixture under the precipitation conditions without using a polymeric dispersant; and introducing a wellbore circulation fluid comprising a plurality of the precipitated particles into a wellbore penetrating a subterranean formation. The precipitation conditions may include one or more of modulating various reaction conditions, applying an electric field to the reaction mixture, or including a carbohydrate-based material in the reaction mixture.

Precipitated particles may be formed under conditions that provide a particle morphology suitable for conveying a desired set of properties to a wellbore circulation fluid. Methods for using precipitated particles in a wellbore may comprise: selecting precipitation conditions for producing precipitated particles that are substantially non-spherical in shape, are about 1 micron or under in size, or any combination thereof; forming the precipitated particles from a reaction mixture under the precipitation conditions without using a polymeric dispersant; and introducing a wellbore circulation fluid comprising a plurality of the precipitated particles into a wellbore penetrating a subterranean formation. The precipitation conditions may include one or more of modulating various reaction conditions, applying an electric field to the reaction mixture, or including a carbohydrate-based material in the reaction mixture.

A method includes masking at least one hole of an article with a paste, wherein the hole opens onto a surface of the article, applying a coating to the surface of the article, and removing the paste including contacting the paste with water, leaving at least one open hole in the surface of the coated article. The paste includes about 40-80 wt % of a filler material, about 0.5-20 wt % of an inorganic binder, about 0.5-15 wt % of a polyhydroxy compound and about 5-25 wt % of water. The filler material includes a first material which includes alkali metal doped alumina, zirconium oxide, titanium oxide, silicon dioxide, or a combination thereof and a second material which includes a silicate. A weight ratio between the first and second materials is in a range of about 1-10.

A method includes masking at least one hole of an article with a paste, wherein the hole opens onto a surface of the article, applying a coating to the surface of the article, and removing the paste including contacting the paste with water, leaving at least one open hole in the surface of the coated article. The paste includes about 40-80 wt % of a filler material, about 0.5-20 wt % of an inorganic binder, about 0.5-15 wt % of a polyhydroxy compound and about 5-25 wt % of water. The filler material includes a first material which includes alkali metal doped alumina, zirconium oxide, titanium oxide, silicon dioxide, or a combination thereof and a second material which includes a silicate. A weight ratio between the first and second materials is in a range of about 1-10.

A slurry for manufacturing gypsum board is disclosed. The slurry comprises calcined gypsum, water, a foaming agent, and a thickening agent. The thickening agent of the present disclosure acts to improve the cohesiveness of the slurry without adversely affecting the setting time of the slurry, the paper-to-core bond (wet and dry), or the head of the slurry by acting as a defoaming agent or coalescing agent. Examples of suitable thickening agents include cellulose ether and co-polymers containing varying degrees of polyacrylamide and acrylic acid. A gypsum board and method of forming the slurry and the gypsum board are also disclosed. The gypsum board comprises a gypsum layer formed from the slurry.

A slurry for manufacturing gypsum board is disclosed. The slurry comprises calcined gypsum, water, a foaming agent, and a thickening agent. The thickening agent of the present disclosure acts to improve the cohesiveness of the slurry without adversely affecting the setting time of the slurry, the paper-to-core bond (wet and dry), or the head of the slurry by acting as a defoaming agent or coalescing agent. Examples of suitable thickening agents include cellulose ether and co-polymers containing varying degrees of polyacrylamide and acrylic acid. A gypsum board and method of forming the slurry and the gypsum board are also disclosed. The gypsum board comprises a gypsum layer formed from the slurry.

A neutron beam shielding gypsum-based building board includes gypsum, a boron-containing material containing boron an amount of which is in a range from 1.0 parts by mass to 120 parts by mass with respect to 100 parts by mass of the gypsum, and a water reducing agent in a range from 0.05 parts by mass to 2.0 parts by mass with respect to 100 parts by mass of the gypsum. The boron-containing material includes one or more kinds selected from calcium borate, boron carbide, boric acid, boron oxide, sodium borate, and calcium boride, and a specific gravity in a dry condition is in a range from 0.65 to 1.6.

A neutron beam shielding gypsum-based building board includes gypsum, a boron-containing material containing boron an amount of which is in a range from 1.0 parts by mass to 120 parts by mass with respect to 100 parts by mass of the gypsum, and a water reducing agent in a range from 0.05 parts by mass to 2.0 parts by mass with respect to 100 parts by mass of the gypsum. The boron-containing material includes one or more kinds selected from calcium borate, boron carbide, boric acid, boron oxide, sodium borate, and calcium boride, and a specific gravity in a dry condition is in a range from 0.65 to 1.6.

Provided herein are fiber reinforced cementitious materials and mixtures with increased crack resistance. The cementitious materials and mixtures include a cement and at least one carbon fiber. Also provide is a fiber reinforced cementitious mortar that includes the fiber reinforced cementitious material to which at least one of water, an aggregate material or a chemical admixture is added.