A lost circulation material (LCM) is provided having an alkaline nanosilica dispersion and an ester activator. The alkaline nanosilica dispersion and the ester activator may form a gelled solid after interaction over a contact period. Methods of lost circulation control using the LCM are also provided.

A lost circulation material (LCM) is provided having an alkaline nanosilica dispersion and an ester activator. The alkaline nanosilica dispersion and the ester activator may form a gelled solid after interaction over a contact period. Methods of lost circulation control using the LCM are also provided.

A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.

A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.

A method of forming a cement composition. The method comprises adding to a hydraulic cementitious material a first strength-enhancing agent and a second strength-enhancing agent, wherein the content of total alkali (Na.sub.2O equivalent) in the hydraulic cementitious material is less than or equal to 0.7% by weight of the cementitious material. The first strength-enhancing agent includes a compound represented by structural formula (I): ##STR00001##
and
the second strength-enhancing agent is sodium sulfate, potassium sulfate, or a mixture thereof. The example values of the variables in structural formula (I) and the example amounts of the first and second strength-enhancing agents being added are defined herein.

A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.

A process for making a layered multi-material structural element having controlled mechanical failure characteristics. The process includes the steps of: supplying a cementitious layer and forming a polymer layer on the cementitious layer by additive manufacture such that the polymer layer has a first thickness and the cementitious layer has a second thickness, wherein the polymer layer comprises a polymer and the cementitious layer comprises a cementitious material; and allowing the polymer from the polymer layer to suffuse into the cementitious layer for a period of time to obtain a suffused zone in the cementitious layer such that the suffused zone has a third thickness that is less than half the second thickness.

To provide a prestressed concrete which can be used for non-primary structural members such as general building members by using a chemical stress induced by an expansive material and a mechanical stress induced by a rust-resistant wire together and achieving reduction in weight and suppression of cracking. A prestressed concrete for non-primary structural members is characterized in that a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced and that the tensional material is a rust-resistant continuous fiber reinforcing wire.

To provide a prestressed concrete which can be used for non-primary structural members such as general building members by using a chemical stress induced by an expansive material and a mechanical stress induced by a rust-resistant wire together and achieving reduction in weight and suppression of cracking. A prestressed concrete for non-primary structural members is characterized in that a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced and that the tensional material is a rust-resistant continuous fiber reinforcing wire.

A composition of matter may include a cement precursor, a phosphazene oligomer and water. A method may include blending a phosphazene oligomer and a cement precursor to form a cement precursor mixture. The method may then include introducing water into the cement precursor mixture to form the cement slurry. A composition of matter may include a cured cement matrix having a polyphosphazene polymer distributed throughout the cement matrix. A method may include cementing a wellbore by introducing a cement slurry into a wellbore, where the cement slurry includes a phosphazene oligomer. The method then includes maintaining the cement slurry such that a cured cement sheath forms, the cement sheath having a polyphosphazene polymer.