Provided is a lost circulation material that may consist essentially of an alkaline nanosilica dispersion and a sodium bicarbonate activator. Further provided are methods that may control lost circulation in a lost circulation zone in a wellbore by introducing the lost circulation material such that it contacts the lost circulation zone and forms a gelled solid in the lost circulation zone.

The present invention relates to a cement additive for use in a blended cement composition, the additive comprising a precipitated calcium carbonate formed from mineral sequestration of carbon dioxide.

An improved mineral binder composition including: a mineral binder including at least 30 weight-% slag, based on the weight of the mineral binder, an activator for the hydration of the slag consisting of or comprising calcium hydroxide and a co-activator consisting of or including at least one salt selected from the group consisting of lithium carbonate, lithium sulfate and sodium carbonate.

An improved mineral binder composition including: a mineral binder including at least 30 weight-% slag, based on the weight of the mineral binder, an activator for the hydration of the slag consisting of or comprising calcium hydroxide and a co-activator consisting of or including at least one salt selected from the group consisting of lithium carbonate, lithium sulfate and sodium carbonate.

A limestone calcined clay cement construction composition comprises a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, and having a Blaine surface area of at least 3800 cm.sup.2/g, in an amount of 180 to 400 kg per m.sup.3 of the freshly mixed construction composition; b) a supplementary cementitious material having a Dv90 of less than 200 μm, in a total amount of 50 to 100 parts by weight, relative to 100 parts by weight of cementitious binder a), the supplementary cementitious material comprising (b-1) a calcined clay material and (b-2) a carbonate rock powder in a weight ratio of (b-1) to (b-2) in the range of 0.5 to 2; c) optionally, an extraneous aluminate source; d) a sulfate source; and e) a polyol in an amount of 0.3 to 2.5 wt.-%, relative to the amount of cementitious binder a). The composition contains available aluminate, calculated as Al(OH).sub.4.sup.−, from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a), in a total amount of at least 0.08 mol, if the amount of cementitious binder a) is in the range of 180 to less than 220 kg per m.sup.3 of the freshly mixed composition, at least 0.06 mol, if the amount of cementitious binder a) is in the range of 220 to less than 280 kg per m.sup.3 of the freshly mixed composition, and at least 0.05 mol, if the amount of cementitious binder a) is 280 kg or more per m.sup.3 of the freshly mixed composition; and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0. The construction composition further comprises f) an ettringite formation controller comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative; and (ii) at least one of (ii-a) a borate source and (ii-b) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.−1 or more, organic carbonates, and mixtures thereof; and g) a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof, (g-2) phosphonic acids and salts thereof, (g-3) polycarboxylic acids and salts thereof, and mixtures thereof. The limestone calcined clay cement construction composition is a reduced carbon footprint composition and exhibits high early strength, high final strength, sufficient open time and high durability. Ingredients of the construction composition are abundantly available.

A limestone calcined clay cement construction composition comprises a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, and having a Blaine surface area of at least 3800 cm.sup.2/g, in an amount of 180 to 400 kg per m.sup.3 of the freshly mixed construction composition; b) a supplementary cementitious material having a Dv90 of less than 200 μm, in a total amount of 50 to 100 parts by weight, relative to 100 parts by weight of cementitious binder a), the supplementary cementitious material comprising (b-1) a calcined clay material and (b-2) a carbonate rock powder in a weight ratio of (b-1) to (b-2) in the range of 0.5 to 2; c) optionally, an extraneous aluminate source; d) a sulfate source; and e) a polyol in an amount of 0.3 to 2.5 wt.-%, relative to the amount of cementitious binder a). The composition contains available aluminate, calculated as Al(OH).sub.4.sup.−, from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a), in a total amount of at least 0.08 mol, if the amount of cementitious binder a) is in the range of 180 to less than 220 kg per m.sup.3 of the freshly mixed composition, at least 0.06 mol, if the amount of cementitious binder a) is in the range of 220 to less than 280 kg per m.sup.3 of the freshly mixed composition, and at least 0.05 mol, if the amount of cementitious binder a) is 280 kg or more per m.sup.3 of the freshly mixed composition; and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0. The construction composition further comprises f) an ettringite formation controller comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative; and (ii) at least one of (ii-a) a borate source and (ii-b) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g.Math.L.sup.−1 or more, organic carbonates, and mixtures thereof; and g) a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof, (g-2) phosphonic acids and salts thereof, (g-3) polycarboxylic acids and salts thereof, and mixtures thereof. The limestone calcined clay cement construction composition is a reduced carbon footprint composition and exhibits high early strength, high final strength, sufficient open time and high durability. Ingredients of the construction composition are abundantly available.

A process for producing foamed concrete includes introducing air pores into aqueous concrete compositions by one or more air pore formers and/or by introducing air. The aqueous concrete compositions are based on one or more foam stabilizers, one or more protective colloid-stabilized polymers of ethylenically unsaturated monomers in the form of aqueous dispersions or water-redispersible powders, 30% to 95% by weight of cement, based on the dry weight of the components for production of the concrete compositions, optionally one or more fillers, and optionally one or more additives.

A process for producing foamed concrete includes introducing air pores into aqueous concrete compositions by one or more air pore formers and/or by introducing air. The aqueous concrete compositions are based on one or more foam stabilizers, one or more protective colloid-stabilized polymers of ethylenically unsaturated monomers in the form of aqueous dispersions or water-redispersible powders, 30% to 95% by weight of cement, based on the dry weight of the components for production of the concrete compositions, optionally one or more fillers, and optionally one or more additives.

A method of producing a carbonated composite material includes: providing a carbonatable cementitious material in particulate form; mixing the carbonatable cementitious material with water to produce a mix; forming a predetermined shape with the mix, wherein the predetermined shape has an initial pore structure containing an initial pore solution having a first pH; pre-conditioning the predetermined shape to remove a predetermined amount of the water from the predetermined shape to produce a pre-conditioned shape; carbonating the pre-conditioned shape in an environment comprising carbon dioxide to produce a modified pore structure containing a modified pore solution having and a second pH, wherein the difference between the first pH and the second pH is represented by a ΔpH, and the ΔpH is 1.0 or less.

A method of producing a carbonated composite material includes: providing a carbonatable cementitious material in particulate form; mixing the carbonatable cementitious material with water to produce a mix; forming a predetermined shape with the mix, wherein the predetermined shape has an initial pore structure containing an initial pore solution having a first pH; pre-conditioning the predetermined shape to remove a predetermined amount of the water from the predetermined shape to produce a pre-conditioned shape; carbonating the pre-conditioned shape in an environment comprising carbon dioxide to produce a modified pore structure containing a modified pore solution having and a second pH, wherein the difference between the first pH and the second pH is represented by a ΔpH, and the ΔpH is 1.0 or less.