Compositions and methods for carbonation curing of cement and/or concrete are provided, where a lixiviant species that solubilizes calcium from oxides and silicates provided with the cement or concrete is included in the curing cement or concrete mixture. Reaction of solubilized calcium with carbon dioxide results in the formation of insoluble calcium carbonate that is incorporated into the structure of the cured cement or concrete, and simultaneously regenerates the lixiviant species. Rapid reaction of carbon dioxide within the curing cement or concrete further generates a concentration gradient that accelerates uptake of additional carbon dioxide, for example from ambient air. This incorporation of environmental carbon also causes the cured cement or concrete to be used for long term carbon sequestration.

Calcium silicate-based cements and concretes are disclosed, which result in concrete compositions that have an improved strength development. A cement product includes a plurality of particles of a carbonatable calcium silicate cement and a first additive; wherein, the first additive is an organic molecule with at least one primary, secondary or tertiary amine group.

Calcium silicate-based cements and concretes are disclosed, which result in concrete compositions that have an improved strength development. A cement product includes a plurality of particles of a carbonatable calcium silicate cement and a first additive; wherein, the first additive is an organic molecule with at least one primary, secondary or tertiary amine group.

Systems for accelerated carbonation curing of a pre-cast cementitious structure may include an ejector and a curing chamber downstream of the ejector. The ejector may be operable to combine a lesser-pressure carbon dioxide containing stream from a carbon dioxide source with a greater-pressure steam to produce a mixed stream including at least steam and carbon dioxide. The mixed stream may have a pressure greater than the pressure of the lesser-pressure carbon dioxide containing stream. The curing chamber may be operable to receive the mixed stream from the ejector and contact the mixed stream with the pre-cast cementitious structure to cure the pre-cast cementitious structure. Processes for accelerated carbonation curing of pre-cast cementitious structures using the systems are also disclosed.

Systems for accelerated carbonation curing of a pre-cast cementitious structure may include an ejector and a curing chamber downstream of the ejector. The ejector may be operable to combine a lesser-pressure carbon dioxide containing stream from a carbon dioxide source with a greater-pressure steam to produce a mixed stream including at least steam and carbon dioxide. The mixed stream may have a pressure greater than the pressure of the lesser-pressure carbon dioxide containing stream. The curing chamber may be operable to receive the mixed stream from the ejector and contact the mixed stream with the pre-cast cementitious structure to cure the pre-cast cementitious structure. Processes for accelerated carbonation curing of pre-cast cementitious structures using the systems are also disclosed.

The carbonate bonded, press-moulded article is produced by press-moulding a particulate, carbonatable material that contains water and by carbonating the obtained compact with carbon dioxide gas. In order to be able to ensure an optimal compressive strength of the article two types of tests are provided. In the first type of test a sample of the particulate material is compressed with an increasing compaction pressure and when water starts to be expelled from the material as from a particular compaction pressure, the press-moulding step is performed with a compaction pressure which is at least 7 MPa smaller than this compaction pressure. In the second type of test different samples of the particulate material are press-moulded with different compaction pressures and, after having released the compaction pressure, the density of the compact is determined. In case this density decreases instead of increases as from a particular compaction pressure, the press-moulding step is performed with a compaction pressure which is smaller than this particular compaction pressure.

The carbonate bonded, press-moulded article is produced by press-moulding a particulate, carbonatable material that contains water and by carbonating the obtained compact with carbon dioxide gas. In order to be able to ensure an optimal compressive strength of the article two types of tests are provided. In the first type of test a sample of the particulate material is compressed with an increasing compaction pressure and when water starts to be expelled from the material as from a particular compaction pressure, the press-moulding step is performed with a compaction pressure which is at least 7 MPa smaller than this compaction pressure. In the second type of test different samples of the particulate material are press-moulded with different compaction pressures and, after having released the compaction pressure, the density of the compact is determined. In case this density decreases instead of increases as from a particular compaction pressure, the press-moulding step is performed with a compaction pressure which is smaller than this particular compaction pressure.

The invention provides compositions and methods directed to carbonation of a cement mix during mixing. The carbonation may be in a stationary mixer or a transportable mixer, such as a drum of a ready-mix truck.

The invention provides compositions and methods directed to carbonation of a cement mix during mixing. The carbonation may be in a stationary mixer or a transportable mixer, such as a drum of a ready-mix truck.

The present disclosure discloses a method and an article for improving the strength of carbonated calcium hydroxide compacts. The method includes the following steps: calcium hydroxide-rich materials, ordinary portland cement, magnesium hydroxide, pottery sand and water are mixed according to the mass ratio of 100:15-20:15-20:40-80:10-20, then the mixture was compressed, carbonated and naturally cured to obtain the carbonated compacts. The present disclosure utilizes cement hydration and magnesium hydroxide carbonation to consume the water produced by calcium hydroxide carbonation, the C-S-H gelation effect produced by cement hydration, the cementation effect of magnesium hydroxide carbonation products, the volume expansion effect of magnesium hydroxide carbonation and the gas transmission channel and internal curing effect of pottery sand further improve the carbonation degree, product gelation, thus greatly improving the strength of carbonated calcium hydroxide compacts.