A method including introducing a well cementing composition into a wellbore, the cementing composition including a pumpable slurry of cement comprising a liquid anti-shrinkage additive including: an aqueous base fluid; a calcined magnesium oxide; and an anti-hydration agent; and allowing at least a portion of the cementing composition to harden. A liquid anti-shrinkage additive for cement including an aqueous base fluid, a calcined magnesium oxide, and an anti-hydration agent.

A method including introducing a well cementing composition into a wellbore, the cementing composition including a pumpable slurry of cement comprising a liquid anti-shrinkage additive including: an aqueous base fluid; a calcined magnesium oxide; and an anti-hydration agent; and allowing at least a portion of the cementing composition to harden. A liquid anti-shrinkage additive for cement including an aqueous base fluid, a calcined magnesium oxide, and an anti-hydration agent.

A delayed-expansion cement mixture or slurry of hydraulic cement contains an expanding agent having hydrophobically modified surfaces with a hydrophobic and/or self-assembling film. A method to delay expansion of cement involves treating the expanding agent with a self-assembling film precursor compound, making the slurry with cement and water, and setting and expanding the cement. A cementing method places the mixture or slurry downhole where it is hardened and expanded.

A delayed-expansion cement mixture or slurry of hydraulic cement contains an expanding agent having hydrophobically modified surfaces with a hydrophobic and/or self-assembling film. A method to delay expansion of cement involves treating the expanding agent with a self-assembling film precursor compound, making the slurry with cement and water, and setting and expanding the cement. A cementing method places the mixture or slurry downhole where it is hardened and expanded.

A shrinkage compensating concrete does not require restraint. The expansive forces developed during hydration compensate for concrete shrinkage, obviating the need for any added internal or external restraint element. Using this new shrinkage compensating concrete, substantially crack-free slabs may be built without using restraining steel bars, fibers, or other separate restraining element. The shrinkage compensating concrete includes a cement that develops internal expansive forces that never exceed the tensile strength of the concrete, such that the internal expansion compensates for the concrete shrinkage. The expansive cement may be an ASTMS, M or S cement, or other expansive cements may also be used.

A shrinkage compensating concrete does not require restraint. The expansive forces developed during hydration compensate for concrete shrinkage, obviating the need for any added internal or external restraint element. Using this new shrinkage compensating concrete, substantially crack-free slabs may be built without using restraining steel bars, fibers, or other separate restraining element. The shrinkage compensating concrete includes a cement that develops internal expansive forces that never exceed the tensile strength of the concrete, such that the internal expansion compensates for the concrete shrinkage. The expansive cement may be an ASTMS, M or S cement, or other expansive cements may also be used.

Methods to prepare a well cementing slurry include coating particles comprising an expanding agent with a component selected from the group consisting of a phenolic resin, a silica, a calcination product of a polysiloxane oil, and a combination thereof; and combining the coated particles with mix water and hydraulic cement to form a cement slurry for cementing a well.

Methods to prepare a well cementing slurry include coating particles comprising an expanding agent with a component selected from the group consisting of a phenolic resin, a silica, a calcination product of a polysiloxane oil, and a combination thereof; and combining the coated particles with mix water and hydraulic cement to form a cement slurry for cementing a well.

A cementitious protective coating material including a mixture of water, one or more of silicon dioxide/sodium silica pozzolans, anhydrous or hydrous sodium or potassium metasilicate; a rheology enhancing admixture; sodium tetraborate, sodium citrate dihydrate, citric acid, or boric acid; and a micro-fiber.

A cementitious protective coating material including a mixture of water, one or more of silicon dioxide/sodium silica pozzolans, anhydrous or hydrous sodium or potassium metasilicate; a rheology enhancing admixture; sodium tetraborate, sodium citrate dihydrate, citric acid, or boric acid; and a micro-fiber.