An aqueous carbonation curing method of a binder composition according to an exemplary embodiment of the present invention includes: forming a binder composition; curing the binder composition in a negative pressure state (pre-curing step); water curing the pre-cured binder composition in an aqueous carbon dioxide absorbent solution (first curing step); and curing the first-cured binder composition in a 95% or more relative humidity atmosphere (second curing step).

An aqueous carbonation curing method of a binder composition according to an exemplary embodiment of the present invention includes: forming a binder composition; curing the binder composition in a negative pressure state (pre-curing step); water curing the pre-cured binder composition in an aqueous carbon dioxide absorbent solution (first curing step); and curing the first-cured binder composition in a 95% or more relative humidity atmosphere (second curing step).

A method for forming cement-based cementitious material includes: pouring a cement paste into a mold; applying an electrical current to the cement paste to perform an electro-osmotic reaction; and transferring the reacted cement paste into a water tank for curing, thereby obtaining a functionally graded cement-based cementitious material. A pair of electrodes is placed in the mold and connected to an external power source. The compressive strength of the functionally graded cement-based cementitious material in the middle is lower than that at either of both ends.

A method for forming cement-based cementitious material includes: pouring a cement paste into a mold; applying an electrical current to the cement paste to perform an electro-osmotic reaction; and transferring the reacted cement paste into a water tank for curing, thereby obtaining a functionally graded cement-based cementitious material. A pair of electrodes is placed in the mold and connected to an external power source. The compressive strength of the functionally graded cement-based cementitious material in the middle is lower than that at either of both ends.

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 invention provides cement additives comprising calcium sulfate and silica which are derived from a material comprising perovskite and silica, along with cements and cementitious products comprising the cement additives. The invention also provides methods for the making the cement additive and cements and cementitious products comprising the cement additives.

The invention provides cement additives comprising calcium sulfate and silica which are derived from a material comprising perovskite and silica, along with cements and cementitious products comprising the cement additives. The invention also provides methods for the making the cement additive and cements and cementitious products comprising the cement additives.

Disclosed herein are methods and compositions for cementing. An example method may comprise providing a cement composition. The cement composition may comprise a composite cementitious material comprising a micronized particulate solid and a monophase amorphous hydraulic binder. The micronized particulate solid may have a mean particle size of about 500 microns or less. The cement composition may further comprise water. The method may further comprise introducing the cement composition into a subterranean formation; and allowing the cement composition to set.

Disclosed herein are methods and compositions for cementing. An example method may comprise providing a cement composition. The cement composition may comprise a composite cementitious material comprising a micronized particulate solid and a monophase amorphous hydraulic binder. The micronized particulate solid may have a mean particle size of about 500 microns or less. The cement composition may further comprise water. The method may further comprise introducing the cement composition into a subterranean formation; and allowing the cement composition to set.