The present invention relates to coloured fiber cement products as well as to methods for manufacturing such products. In particular, the present invention provides coloured fiber cement products, which fiber cement products are coloured in the mass, and at least comprise on at least part of their outer surface one or more cured layers of a coating composition, which composition at least comprises a binder and a pigment and/or a filler and is characterized by a pigment volume concentration (PVC) of between about 1% and about 20%. The present invention further provides processes for producing these coloured fiber cement products. Finally, the present invention provides uses of the coloured fiber cement products as building materials. In particular embodiments, the fiber cement products produced by the processes of the present invention can be used to provide an outer surface to walls, both internal as well as external, a building or construction, e.g. as fagade plate, siding, etc.

A sulfate-resistant cement composition may contain calcium magnesium aluminum oxide silicate, brownmillerite, dolomite, periclase, and calcium aluminum oxide. The composition may contain the calcium aluminum oxide in an amount in the range of 0.01 to 2.0 wt. %. The composition may contain the brownmillerite in an amount of the range of 20 to 30 wt. %.

A composition is provided. The composition consists essentially of (a) 1 to 30 wt. % of a hydrogen phosphate selected from the group consisting of mono and dihydrogen phosphates of sodium, potassium, ammonium, magnesium, calcium, aluminium, zinc, iron, cobalt, and copper; (b) 1 to 40 wt. % of a compound selected from the group consisting of oxides, hydroxides, and oxide hydrates of magnesium, calcium, iron, zinc, and copper; (c) 40 to 95 wt. % of a particulate filler selected from the group consisting of glass; mono-, oligo- and poly-phosphates of magnesium, calcium, barium and aluminum; calcium sulfate; barium sulfate; simple and complex silicates; simple and complex aluminates; simple and complex titanates; simple and complex zirconates; zirconium dioxide; titanium dioxide; aluminum oxide; silicon dioxide; silicon carbide; aluminum nitride; boron nitride and silicon nitride; and (d) 0 to 25 wt. % of a constituent that differs from constituents (a) to (c).

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 provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.

The invention provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.

A colored cementitious composition is provided that is composed of hydraulic cement and a liquid coloring suspension. The liquid coloring suspension for cementitious compositions contains polycarboxylate dispersant, pigment, and a polysaccharide thixotropic additive. The liquid coloring suspension has improved viscosity consistency, improved shelf-life, anti-settling and anti-sludging properties, and decreased polycarboxylate dispersant requirements.

A colored cementitious composition is provided that is composed of hydraulic cement and a liquid coloring suspension. The liquid coloring suspension for cementitious compositions contains polycarboxylate dispersant, pigment, and a polysaccharide thixotropic additive. The liquid coloring suspension has improved viscosity consistency, improved shelf-life, anti-settling and anti-sludging properties, and decreased polycarboxylate dispersant requirements.

The effectiveness of expansive cement systems may be diluted when, during a well cementing operation, commingling takes place between the cement slurry and a spacer fluid, a drilling fluid, or both. Incorporating expansive agents in the spacer fluid or drilling fluid may reduce or negate the loss of expansion at the cement slurry/spacer interface or the cement slurry/drilling fluid interface, thereby promoting zonal isolation throughout the cemented interval.