A retarder mixture for oil and gas well cementing includes a lignosulfonate compound and at least one hydrolyzed carbohydrate. A method includes blending the retarder mixture and a cement precursor to form a cement precursor mixture and introducing water into the cement precursor mixture to form a cement mixture. The cement mixture is pumped down a well and cures to form a cement sheath containing the cement precursor and the retarder mixture.

Three pumpable geopolymer compositions for well sealing application is disclosed herein. One pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate activator solution with a very low SiO.sub.2/M.sub.2O. Another pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate-free activator solution that may contain an alkali salt; and (iv) powdered alkali silicate glass. The third pumpable geopolymer composition comprises (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline low silicate activator solution; and (iv) powdered alkali silicate glass.

Three pumpable geopolymer compositions for well sealing application is disclosed herein. One pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate activator solution with a very low SiO.sub.2/M.sub.2O. Another pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate-free activator solution that may contain an alkali salt; and (iv) powdered alkali silicate glass. The third pumpable geopolymer composition comprises (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline low silicate activator solution; and (iv) powdered alkali silicate glass.

Disclosed are a cement composition additive with improved compressive strength and workability, including a polycarboxylic acid copolymer and/or a salt thereof, zinc oxide particles, and a predetermined amount of gluconic acid and/or a salt thereof, and a cement composition containing the same.

Provided are: a borehole cement slurry additive that is capable of suppressing the generation of free water from cement slurries in any environment, whether cold regions, mild regions, or hot regions; and a method for storing the same. The borehole cement slurry additive contains: an aqueous dispersion of silica having an average particle size of 3-200 nm as determined via dynamic light scattering; and a compound having an alcoholic hydroxyl group as a dispersion stabilizer, the compound being included in an amount of 1-30 mol per 1,000 g dispersion medium in the aqueous silica dispersion.

Provided are: a borehole cement slurry additive that is capable of suppressing the generation of free water from cement slurries in any environment, whether cold regions, mild regions, or hot regions; and a method for storing the same. The borehole cement slurry additive contains: an aqueous dispersion of silica having an average particle size of 3-200 nm as determined via dynamic light scattering; and a compound having an alcoholic hydroxyl group as a dispersion stabilizer, the compound being included in an amount of 1-30 mol per 1,000 g dispersion medium in the aqueous silica dispersion.

The present invention provides a geopolymer cement, comprising: a geopolymer binder; and a setting control composition comprising: a viscosity control agent, a polymeric binder, and a retarding additive. The invention also relates to a geopolymer concrete comprising the geopolymer cement of the invention and aggregate material. The invention further relates to a method for controlling open time in a geopolymer composition, wherein a sufficient quantity of the setting control composition is added such that the open time is between 30 and 120 minutes. The present invention provides particular uses in construction of walls, flooring, and roofing, especially lightweight prefabricated panels intended to be used as structural, insulating or cladding elements.

A two-component mortar system, which includes a component A; and a component B, which is in aqueous-phase for initiating a curing process. Component A comprises water, aluminous cement, at least one plasticizer, and at least one blocking agent selected from the group consisting of phosphoric acid, metaphosphoric acid, phosphorous acid, and a phosphoric acid. Component B includes an initiator, at least one retarder, at least one mineral filler, and water.

An additive for a cement slurry for a well that is capable of suppressing the generation of free water and preventing flotation/separation of low-specific-gravity aggregate while securing sufficient cement strength even at a high temperature and a method for producing this additive are disclosed. The additive contains an aqueous dispersion of silica and a layered silicate.

An additive for a cement slurry for a well that is capable of suppressing the generation of free water and preventing flotation/separation of low-specific-gravity aggregate while securing sufficient cement strength even at a high temperature and a method for producing this additive are disclosed. The additive contains an aqueous dispersion of silica and a layered silicate.