A radiation shield unit, which shields against neutron rays, X-rays, and γ-rays, contains 10 vol % or more and 90 vol % or less of gadolinium.

A radiation shield unit, which shields against neutron rays, X-rays, and γ-rays, contains 10 vol % or more and 90 vol % or less of gadolinium.

A colored cementitious composition is provided that is composed of hydraulic cement and a liquid coloring suspension. The liquid coloring suspension for cementitious compositions contains polycarboxylate dispersant, pigment, and a polysaccharide thixotropic additive. The liquid coloring suspension has improved viscosity consistency, improved shelf-life, anti-settling and anti-sludging properties, and decreased polycarboxylate dispersant requirements.

A colored cementitious composition is provided that is composed of hydraulic cement and a liquid coloring suspension. The liquid coloring suspension for cementitious compositions contains polycarboxylate dispersant, pigment, and a polysaccharide thixotropic additive. The liquid coloring suspension has improved viscosity consistency, improved shelf-life, anti-settling and anti-sludging properties, and decreased polycarboxylate dispersant requirements.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

The effectiveness of expansive cement systems may be diluted when, during a well cementing operation, commingling takes place between the cement slurry and a spacer fluid, a drilling fluid, or both. Incorporating expansive agents in the spacer fluid or drilling fluid may reduce or negate the loss of expansion at the cement slurry/spacer interface or the cement slurry/drilling fluid interface, thereby promoting zonal isolation throughout the cemented interval.

A method of making building materials from an aqueous solution includes receiving the aqueous solution with dissolved ions and increasing a pH of the aqueous solution so the dissolved ions precipitate from the aqueous solution as salt. The method also includes collecting the salt precipitated from the aqueous solution and forming the building materials from the salt.

A method of making building materials from an aqueous solution includes receiving the aqueous solution with dissolved ions and increasing a pH of the aqueous solution so the dissolved ions precipitate from the aqueous solution as salt. The method also includes collecting the salt precipitated from the aqueous solution and forming the building materials from the salt.

The present invention relates to a cementitous composite specifically engineered to possess self-cleaning abilities while maintaining their unique strain-hardening behaviour and the preparation of the said composite. The cementitious composite comprises a hydraulic cement, a plurality of fibers, in particular polyvinyl alcohol fibers wherein the ratio of the plurality of fibers to the hydraulic cement is in a range from 1 to 3% by volume; a self-cleaning agent, in particular nanoparticulate titanium dioxide (TiO.sub.2) wherein the weight ratio of the self-cleaning agent to the hydraulic cement is in a range from 0.01 to 1.