Cement slurries are provided for use in cementing oil and gas wells. The cement slurry comprises API Class C or Class H Portland cement and a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash. Pumice is present in the mixtures in amounts at least about 40 wt % of the pozzolan. The weight ratio of the pozzolan to the cement is from about 35:65 to about 70:30. The novel cement slurries preferably will not comprise any additional lime, including hydrated lime, or other activators.

Cement slurries are provided for use in cementing oil and gas wells. The cement slurry comprises API Class C or Class H Portland cement and a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash. Pumice is present in the mixtures in amounts at least about 40 wt % of the pozzolan. The weight ratio of the pozzolan to the cement is from about 35:65 to about 70:30. The novel cement slurries preferably will not comprise any additional lime, including hydrated lime, or other activators.

A low-calcium silicate cement consists of calcium oxide, silica, alumina, and iron oxide. A preparation method of the low-calcium silicate cement consists of: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300? C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m.sup.2/Kg, thereby obtaining a low-calcium silicate cement.

The disclosure provides an ultralow-carbon clinker-free cement, prepared from the following raw materials: granulated blast-furnace slag, gypsum and calcium oxide-based materials. The granulated blast-furnace slag accounts for 65%-95% of the total weight of the raw materials, the gypsum accounts for 4.5%-34.5% of the total weight of the raw materials, and the balance is the calcium oxide-based material. A weight percentage of calcium oxide and/or calcium hydroxide in the total weight of the raw materials is controlled to be 0.05%-0.75%. The disclosure further provides a method for preparing the ultralow-carbon clinker-free cement and application of the ultralow-carbon clinker-free cement in the preparation of concrete, mortar or cement products. The ultralow-carbon clinker-free cement of the disclosure has the advantages of high early strength, ultrahigh long-term strength, low shrinkage, carbonation resistance, low carbon emissions, etc.

A low-calcium silicate cement, comprising: based on the total mass of oxides as 1, 50-60% of calcium oxide, 30-45% of silica, 2-6% of alumina, and 1-4% of iron oxide. A preparation method of the low-calcium silicate cement comprises: subjecting raw materials to crushing, joint grinding and uniform mixing to obtain a low-calcium silicate cement raw meal; calcining the above low-calcium silicate cement raw meal at 1050-1300? C. for 30-90 min, and cooling to obtain low-calcium silicate cement clinker; and levigating the above low-calcium silicate cement clinker till a specific surface area is 400-500 m.sup.2/Kg, thereby obtaining a low-calcium silicate cement.

Methods and composition are provided for deriving cement and/or supplementary cementitious materials, such as pozzolans, from one or more non-limestone materials, such as one or more non-limestone rocks and/or minerals. The non-limestone materials, e.g., non-limestone rocks and/or minerals, are processed in a manner that a desired product, e.g., cement and/or supplementary cementitious material, is produced.

The invention relates to improved non-efflorescing cement-free and water-dispersible powder building material compositions comprising a homopolymer or copolymer as binder, useful for the preparation of wet formulations of plasters grouts, waterproofing coatings or mortars for the construction and the civil engineering industry. The binder is obtained by spray-drying or lyophilization of a dispersion containing a polymer and a protective colloid. These compositions also comprise a deprotection agent and a specific adsorbent filler. The invention also refers to the methods of preparation of these dry compositions and wet formulations, the application of these latter onto the surface of buildings or civil engineering works, the so obtained coatings as well as the so coated elements. The hardened products obtained therefrom are remarkably water-resistant, non efflorescent and easy to obtain.

Disclosed are gypsum boards and methods of preparing gypsum board using silica fume. The board contains a set gypsum core disposed between two cover sheets. The core is formed from a core slurry comprising water, stucco, and silica fume. The silica fume is dispersed before adding into the gypsum slurry. The gypsum board demonstrates desirable fire-resistance properties when subjected to various high temperature shrinkage and thermal insulation tests according to ASTM C1795-15. The dispersed silica fume surprisingly and unexpectedly allows for enhancing the fire resistance of gypsum board. In embodiments, the presence of the silica fume in the core slurry allows for excluding expandable vermiculite therein.

A fresh concrete composition for producing a magnetizable concrete, including 250-450 kg/m.sup.3 of cement, 50-150 kg/m.sup.3 of a mineral addition, 2900-3500 kg/m.sup.3 of aggregates containing magnetizable particles, and 100-150 kg/m.sup.3 water, wherein the sand volume is 60 vol.-%.