Methods of wellbore cementing are provided. A method of cementing may comprise calculating a lime to silica correlation for two or more cementitious components of a cement composition; and adjusting a concentration of at least one of the cementitious components such that the lime to silica correlation meets or exceeds a target.

Portland cement compositions for use in high-temperature, high pressure wells are designed such that the lime-to-silica molar ratio is between 0.5 and 1.0, and the alumina-to-silica molar ratio is between 0.05 and 0.10. After curing and setting at temperatures between 85° C. and 300° C., the cement compositions form tobermorite as an initial and permanent calcium silicate hydrate phase.

Portland cement compositions for use in high-temperature, high pressure wells are designed such that the lime-to-silica molar ratio is between 0.5 and 1.0, and the alumina-to-silica molar ratio is between 0.05 and 0.10. After curing and setting at temperatures between 85° C. and 300° C., the cement compositions form tobermorite as an initial and permanent calcium silicate hydrate phase.

Portland cement compositions for use in high-temperature, high pressure wells are designed such that the lime-to-silica molar ratio is between 0.5 and 1.0, and the alumina-to-silica molar ratio is between 0.05 and 0.10. After curing and setting at temperatures between 85° C. and 300° C., the cement compositions form tobermorite as an initial and permanent calcium silicate hydrate phase.

Cementitious compositions comprising a hydraulic cementitious material, a compound selected from the group consisting of a polyhydroxy aromatic compound, a polycarboxylic acid-containing compound or a salt thereof, ascorbic acid or a salt thereof, or a combination thereof, and a particulate material or a water soluble silicate-containing material that interacts with the compound are described herein. The polyhydroxy aromatic compound can be a water soluble compound having from two to thirty hydroxyl groups. The particulate material can exhibit a particle size distribution, wherein at least about 90% by weight of the particles have a diameter of less than 2 mm. Suitable particulate materials include nanoparticles and microparticles. The cementitious compositions can be used to form building materials. The cementitious compositions are especially suited for inhibiting corrosion of reinforcing steel bars embedded in concrete mixtures. Methods of making and using the cementitious composition are also disclosed.

The invention concerns a polycondensate containing (I) at least a structural unit, which is an aromatic moiety bearing a polyether side chain comprising 9 to 41 alkylene glycol units, (II) at least a structural unit, which is an aromatic moiety bearing at least one phosphoric acid ester group and (III) at least a methylene unit (—CH.sub.2—), the polycondensate having a polycondensation degree of 10 to 75. Also concerned are building material mixtures containing said polycondensates and the use as dispersant for inorganic binders.

Methods of using the set-delayed cement slurries and compositions resulting from the combination of the set-delayed cement slurries are also described. A method may comprise providing a first set-delayed cement slurry comprising a pozzolanic cement and/or a Portland cement, water, and a first cement set retarder; providing a second set-delayed cement slurry comprising calcium-aluminate and a second cement set retarder; mixing the first slurry and the second slurry to form a cement composition; and allowing the cement composition to set.

Methods of using the set-delayed cement slurries and compositions resulting from the combination of the set-delayed cement slurries are also described. A method may comprise providing a first set-delayed cement slurry comprising a pozzolanic cement and/or a Portland cement, water, and a first cement set retarder; providing a second set-delayed cement slurry comprising calcium-aluminate and a second cement set retarder; mixing the first slurry and the second slurry to form a cement composition; and allowing the cement composition to set.

Methods of using the set-delayed cement slurries and compositions resulting from the combination of the set-delayed cement slurries are also described. A method may comprise providing a first set-delayed cement slurry comprising a pozzolanic cement and/or a Portland cement, water, and a first cement set retarder; providing a second set-delayed cement slurry comprising calcium-aluminate and a second cement set retarder; mixing the first slurry and the second slurry to form a cement composition; and allowing the cement composition to set.

Disclosed is a method of cementing. The method comprises providing a set-delayed cement composition comprising water, pumice, hydrated lime, a set retarder, and a micro-electrical-mechanical system; and allowing the set-delayed cement composition to set.