Provided herein are fiber reinforced cementitious materials and mixtures with increased crack resistance. The cementitious materials and mixtures include a cement and at least one carbon fiber. Also provide is a fiber reinforced cementitious mortar that includes the fiber reinforced cementitious material to which at least one of water, an aggregate material or a chemical admixture is added.

Embodiments provide a method of encapsulating a solid cement additive. The method includes the step of applying a base film-forming monomer to the solid cement additive. The method includes the step of forming a coating layer surrounding the solid cement additive. The coating layer includes the base film-forming monomer. The method includes the step of applying an overlay film-forming monomer to the coating layer surrounding the solid cement additive. The method includes the step of reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The solid cement additive includes solid particles useful in cementing applications. The polymer shell includes a crosslinked polymer. The polymer shell surrounds the solid cement additive. The polymer shell has a permeability to water allowing controlled release of the solid cement additive.

Embodiments provide a method of encapsulating a solid cement additive. The method includes the step of applying a base film-forming monomer to the solid cement additive. The method includes the step of forming a coating layer surrounding the solid cement additive. The coating layer includes the base film-forming monomer. The method includes the step of applying an overlay film-forming monomer to the coating layer surrounding the solid cement additive. The method includes the step of reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The solid cement additive includes solid particles useful in cementing applications. The polymer shell includes a crosslinked polymer. The polymer shell surrounds the solid cement additive. The polymer shell has a permeability to water allowing controlled release of the solid cement additive.

A method of using a gas control additive to provide gas migration control in a wellbore includes the steps of mixing the gas control additive with a cement to form a cement slurry, where the gas control additive includes a semi-permeable membrane and a scrubbing agent, such that the semi-permeable membrane forms a shell around a core such that the scrubbing agent is in the core, introducing the cement slurry to the wellbore, and reacting the scrubbing agent with an antagonistic gas to produce a helper byproduct, where the antagonistic gas migrates from a hydrocarbon-bearing formation into the wellbore and permeates through the semi-permeable membrane to the core of the gas control additive.

A method of using a gas control additive to provide gas migration control in a wellbore includes the steps of mixing the gas control additive with a cement to form a cement slurry, where the gas control additive includes a semi-permeable membrane and a scrubbing agent, such that the semi-permeable membrane forms a shell around a core such that the scrubbing agent is in the core, introducing the cement slurry to the wellbore, and reacting the scrubbing agent with an antagonistic gas to produce a helper byproduct, where the antagonistic gas migrates from a hydrocarbon-bearing formation into the wellbore and permeates through the semi-permeable membrane to the core of the gas control additive.

A method of forming a core-shell composite material includes depositing a polysiloxane shell to wrap a ceramic core via chemical vapor deposition for forming a core-shell composite material, wherein the ceramic core is an oxide of metal and silicon, which includes 100 parts by weight of calcium, 50 to 95 parts by weight of iron, 15 to 40 parts by weight of silicon, 2 to 15 parts by weight of magnesium, 2 to 20 parts by weight of aluminum, and 2 to 10 parts by weight of manganese.

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.

Embodiments provide a method for controlled release of a cement additive for use in a wellbore. The method includes the steps of mixing an aramide capsule with a cement slurry to form an additive-containing slurry, and introducing the additive-containing slurry into the wellbore. The aramide capsule is formed by interfacial polymerization where an aramide polymer forms a semi-permeable membrane encapsulating the cement additive.

Embodiments provide a method for controlled release of a cement additive for use in a wellbore. The method includes the steps of mixing an aramide capsule with a cement slurry to form an additive-containing slurry, and introducing the additive-containing slurry into the wellbore. The aramide capsule is formed by interfacial polymerization where an aramide polymer forms a semi-permeable membrane encapsulating the cement additive.