Hexavalent chromium-free slurries are provided that are capable of achieving a full cure at temperatures as low as 330-450 degrees F., thus making the coatings especially suitable for application on temperature sensitive base materials. The slurries are suitable in the production of protective coating systems formed by novel silicate-based basecoats that are sealed with novel phosphate-based topcoats. The coating systems exhibit acceptable corrosion and heat resistance and are capable of replacing traditional chromate-containing coating systems.

Methods and systems for the treatment of wells are disclosed. A method for treating a well comprises providing a treatment fluid comprising calcium-aluminate cement, water, and a cement set retarder; and introducing the treatment fluid into a wellbore. A system for treating a well comprises a treatment fluid comprising calcium-aluminate cement, water, and a cement set retarder; a vessel to contain the treatment fluid; a pumping system coupled to the vessel to pump the treatment fluid; and a conduit coupled to the pumping system.

Methods and systems for the treatment of wells are disclosed. A method for treating a well comprises providing a treatment fluid comprising calcium-aluminate cement, water, and a cement set retarder; and introducing the treatment fluid into a wellbore. A system for treating a well comprises a treatment fluid comprising calcium-aluminate cement, water, and a cement set retarder; a vessel to contain the treatment fluid; a pumping system coupled to the vessel to pump the treatment fluid; and a conduit coupled to the pumping system.

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 extended-life cement compositions are disclosed. A method comprises providing an extended-life cement composition comprising calcium-aluminate cement, water, and a cement set retarder. The method additionally comprises mixing the extended-life cement composition with a cement set activator to activate the extended-life cement composition. The method further comprises Introducing the activated extended-life cement composition into a subterranean formation and allowing the activated extended-life cement composition to set in the subterranean formation; wherein the activated extended-life cement composition has a thickening time of greater than about two hours.

Methods of using extended-life cement compositions are disclosed. A method comprises providing an extended-life cement composition comprising calcium-aluminate cement, water, and a cement set retarder. The method additionally comprises mixing the extended-life cement composition with a cement set activator to activate the extended-life cement composition. The method further comprises Introducing the activated extended-life cement composition into a subterranean formation and allowing the activated extended-life cement composition to set in the subterranean formation; wherein the activated extended-life cement composition has a thickening time of greater than about two hours.

A process is provided for treating raw fly ash used in cementitious material so as to increase the strength of the cementitious material while at the same time providing a near linear strength increase for the material as it cures by processing the raw fly ash, as by milling, and by mixing the processed fly ash with a catalyst such as lithium, with the lithium concentration in the fly ash being between 0.05% and 0.25% by weight. The process applies to Class C fly ash and Class F fly ash when mixed with Class C fly ash. All of the above processes include the use of polycarboxylates.

A process is provided for treating raw fly ash used in cementitious material so as to increase the strength of the cementitious material while at the same time providing a near linear strength increase for the material as it cures by processing the raw fly ash, as by milling, and by mixing the processed fly ash with a catalyst such as lithium, with the lithium concentration in the fly ash being between 0.05% and 0.25% by weight. The process applies to Class C fly ash and Class F fly ash when mixed with Class C fly ash. All of the above processes include the use of polycarboxylates.

Lithium-treated calcium aluminate cement (CAC)-based products, concretes, and related techniques are disclosed. In accordance with some embodiments, a lithium-treated CAC mixture may be produced by intergrinding ground-down CAC, class C fly ash, a lithium compound, and a polycarboxylate material. In accordance with some embodiments, a cementitious material may be produced by intergrinding said lithium-treated CAC mixture with class C fly ash, sodium citrate, and a polycarboxylate material. In accordance with some embodiments, a concrete may be produced by mixing said cementitious material (including said lithium-treated CAC mixture) with rock, sand, and water.