Embodiments of a dry mix for producing a concrete composition are provided. The dry mix includes aggregate, cement, and bed ash. The bed ash contains the combustion product of a fluidized bed coal combustion reaction. Additionally, embodiments of a method of preparing the dry mix and embodiments of a method of preparing a concrete composition are provided. The dry mix is also suitable for repairing soil slips, and embodiments of a method of repairing a soil slip are also provided.

A cement slurry in a downhole well has a composition that includes a cement in an amount of 60% to 80% by weight of the cement slurry, water in an amount of 20% to 40% by weight of the cement slurry, and a retarder in an amount of 0.1% to 2% by weight of the cement slurry. The cement includes 70% to 90% of at least one silicate by weight of the cement. The retarder includes sodium lignosulfonate with an alkali content of no more than 5.0 g Na.sub.2O equivalent/liter of admixture.

A cement slurry in a downhole well has a composition that includes a cement in an amount of 60% to 80% by weight of the cement slurry, water in an amount of 20% to 40% by weight of the cement slurry, and a retarder in an amount of 0.1% to 2% by weight of the cement slurry. The cement includes 70% to 90% of at least one silicate by weight of the cement. The retarder includes sodium lignosulfonate with an alkali content of no more than 5.0 g Na.sub.2O equivalent/liter of admixture.

Cement slurries are prepared that comprise water, a hydraulic cement, particles of an oil-absorbent particles and non-swellable hydrophobic particles. The particles are present in an amount sufficient to alter a property of a non-aqueous drilling fluid. The cement slurry is placed in a subterranean well, whereupon the slurry contacts residual drilling fluid on casing and formation surfaces. The oil-absorbent particles and hydrophobic particles in the cement slurry may reduce the mobility of the drilling fluid, thereby improving zonal isolation.

Cement slurries are prepared that comprise water, a hydraulic cement, particles of an oil-absorbent particles and non-swellable hydrophobic particles. The particles are present in an amount sufficient to alter a property of a non-aqueous drilling fluid. The cement slurry is placed in a subterranean well, whereupon the slurry contacts residual drilling fluid on casing and formation surfaces. The oil-absorbent particles and hydrophobic particles in the cement slurry may reduce the mobility of the drilling fluid, thereby improving zonal isolation.

The invention relates to a method for layer-by-layer deposition of concrete by providing extrudable concrete. A first flow comprising a binder material and water and a second flow comprising a carrier material, an additional component and water are mixed in a static mixer to form a third flow of extrudable concrete. The material of the second flow has a shorter initial setting time than the material of the first flow. The first flow has a first viscosity V1 and the second flow has a second viscosity V2 so that the ratio V1/V2 ranges between 1/40 and 40. The third flow has a viscosity larger than the viscosity of the first flow and the second flow and a yield stress larger than the yield stress of the first flow and the second flow. The material of the third flow has an initial setting time shorter than initial setting time of the first flow.

The invention further relates to a system to extrude concrete, in particular for layer-by-layer deposition of concrete.

The invention relates to a method for layer-by-layer deposition of concrete by providing extrudable concrete. A first flow comprising a binder material and water and a second flow comprising a carrier material, an additional component and water are mixed in a static mixer to form a third flow of extrudable concrete. The material of the second flow has a shorter initial setting time than the material of the first flow. The first flow has a first viscosity V1 and the second flow has a second viscosity V2 so that the ratio V1/V2 ranges between 1/40 and 40. The third flow has a viscosity larger than the viscosity of the first flow and the second flow and a yield stress larger than the yield stress of the first flow and the second flow. The material of the third flow has an initial setting time shorter than initial setting time of the first flow.

The invention further relates to a system to extrude concrete, in particular for layer-by-layer deposition of concrete.

A hydraulic binder including (in % by dry weight); A. at least 50 of at least one ground and granulated blast-furnace slag; B. more than 5 of at least one calcium aluminate cement and/or of at least one calcium sulfoaluminate cement; C. more than 5 of at least one source of sulfate ions; D. between 1 and 5 of Ca(OH).sub.2 and/or Portland cement; E. between 0.01 and 1 of at least one alkali metal carbonate; F. and at least one alkalifying reagent consisting of at least one alkali metal carbonate and/or bicarbonate, different from E; under the following conditions: (i) amount of C allows sulfate ions of C to react with B and A; (ii) the amount of F sufficiently causes a reaction with D in water resulting in a wet formulation with a pH not less than 12, for a water-to-mortar mixing rate between 10 and 35% by weight.

A hydraulic binder including (in % by dry weight); A. at least 50 of at least one ground and granulated blast-furnace slag; B. more than 5 of at least one calcium aluminate cement and/or of at least one calcium sulfoaluminate cement; C. more than 5 of at least one source of sulfate ions; D. between 1 and 5 of Ca(OH).sub.2 and/or Portland cement; E. between 0.01 and 1 of at least one alkali metal carbonate; F. and at least one alkalifying reagent consisting of at least one alkali metal carbonate and/or bicarbonate, different from E; under the following conditions: (i) amount of C allows sulfate ions of C to react with B and A; (ii) the amount of F sufficiently causes a reaction with D in water resulting in a wet formulation with a pH not less than 12, for a water-to-mortar mixing rate between 10 and 35% by weight.

A cement composition can include water; cement, wherein less than 75 w/w % of the total amount of the cement is Portland cement; and a fluid loss additive, wherein the fluid loss additive comprises a polymer network having at least one branching point formed with a monomer and a cross-linking agent that comprises at least three active functional groups. The cement can also be a non-Portland cement. The monomer can be a vinyl ester-based monomer that is polymerized with the cross-linking agent to form the polymer network. The cement composition can be used in an oil and gas operation.