The invention provides a low density cement composition. The composition includes a cement component, a glass sphere component, a bentonite component, a fine calcium carbonate component, a medium calcium carbonate component, a silica sand component, and a silica flour component.

The invention provides a low density cement composition. The composition includes a cement component, a glass sphere component, a bentonite component, a fine calcium carbonate component, a medium calcium carbonate component, a silica sand component, and a silica flour component.

Three pumpable geopolymer compositions for well sealing application is disclosed herein. One pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate activator solution with a very low SiO.sub.2/M.sub.2O. Another pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate-free activator solution that may contain an alkali salt; and (iv) powdered alkali silicate glass. The third pumpable geopolymer composition comprises (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline low silicate activator solution; and (iv) powdered alkali silicate glass.

Three pumpable geopolymer compositions for well sealing application is disclosed herein. One pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate activator solution with a very low SiO.sub.2/M.sub.2O. Another pumpable geopolymer composition comprises: (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline silicate-free activator solution that may contain an alkali salt; and (iv) powdered alkali silicate glass. The third pumpable geopolymer composition comprises (i) less reactive aluminosilicate; (ii) more reactive aluminosilicate; (iii) alkaline low silicate activator solution; and (iv) powdered alkali silicate glass.

An object to provide a prestressed concrete that can be widely used for general building members, in which a chemical stress induced by an expansive material and a mechanical stress induced by a continuous fiber reinforcing wire are simultaneously used together, and due to a synergistic effect of the mechanical stress and the chemical stress, the strength is increased, the reduction in weight, reduction in thickness, and suppression of cracking are achieved, and the degree of freedom in design increased. To provide a prestressed concrete characterized in that, in a concrete into which a prestress is introduced, a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced simultaneously into the concrete, the tensional material is a continuous fiber reinforcing wire, the expansive material for a concrete is contained in an amount of 5 to 30 kg/m3, and aluminum oxide contained in an amount of 0.2 to 2.0% by weight to the expansive material.

An object to provide a prestressed concrete that can be widely used for general building members, in which a chemical stress induced by an expansive material and a mechanical stress induced by a continuous fiber reinforcing wire are simultaneously used together, and due to a synergistic effect of the mechanical stress and the chemical stress, the strength is increased, the reduction in weight, reduction in thickness, and suppression of cracking are achieved, and the degree of freedom in design increased. To provide a prestressed concrete characterized in that, in a concrete into which a prestress is introduced, a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced simultaneously into the concrete, the tensional material is a continuous fiber reinforcing wire, the expansive material for a concrete is contained in an amount of 5 to 30 kg/m3, and aluminum oxide contained in an amount of 0.2 to 2.0% by weight to the expansive material.

Expansive cement compositions for use in subterranean wellbores that include a monophase amorphous hydraulic binder material (MAHBM). The MAHBM may include a plurality of particles having a silica core and an amorphous coating substantially surrounding the silica core. The coating may comprise, for example, a plurality of amorphous α-dicalcium silicate hydrate nanoparticles or microparticles. The MAHBM may be used as an expansion agent in a cement composition or used as an expansive cement by itself.

Expansive cement compositions for use in subterranean wellbores that include a monophase amorphous hydraulic binder material (MAHBM). The MAHBM may include a plurality of particles having a silica core and an amorphous coating substantially surrounding the silica core. The coating may comprise, for example, a plurality of amorphous α-dicalcium silicate hydrate nanoparticles or microparticles. The MAHBM may be used as an expansion agent in a cement composition or used as an expansive cement by itself.

A precast concrete structure formed of a cementitious mixture is provided, the cementitious mixture comprising a mixture of: (a) cement, (b) silica fume, (c) supplemental material (limestone and/or slag), (d) masonry sand, (e) water and ice (f) plasticizers and (g) workability admixtures. The result is an improved concrete for use in the formation of long span bridge elements that are simple and safe to manufacture and having improved properties. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

A dry mineral binder composition includes cement and mineral fillers for the manufacture of molded parts by way of 3D printing. The binder composition additionally contains at least one aluminum sulfate-based accelerator, at least one polycarboxylate ether-based super-plasticizer and at least one rheology additive.