Methods for preparing a carbonated supplementary cementitious materials, including semi-wet carbonation, cyclic carbonation, non-slurry carbonation, high temperature carbonation and/or granular carbonation of a carbonatable material.

Generating methane by adding hydrogen to CO.sub.2 in exhaust gas discharged a from cement production facility or CO.sub.2 that is separated and recovered from the exhaust gas, and using the methane as an alternative fuel to fossil fuel such as coal, petroleum, natural gas and the like, by methanation of CO.sub.2 in the exhaust gas from the cement production facility that includes exhaust gas originated from lime stone not from the fossil oil and effectively utilizing it, it is possible to reduce usage of the fossil fuel, suppress CO.sub.2 originated from energy, and improve an effect of reducing greenhouse gas.

Methods of preparing engineered cementitious composite precursors include carbonating a fly ash comprising >about 25% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the fly ash to a first gas stream comprising carbon dioxide to form a carbonated fly ash. A steel slag is also carbonated that comprises >about 40% by weight of calcium oxide (CaO) and having a water content of >about 12% to <about 18% by weight of water by exposing the steel slag to a second gas stream comprising carbon dioxide to form a carbonated steel slag. The carbonated fly ash and the carbonated steel slag are suitable for use as engineered cementitious composite precursors in a bendable engineered cementitious composite composition that further comprises Portland cement, a polymeric fiber, and a superplasticizer.

Improved cement for concrete is provided having reduced carbon footprint and improved mechanical properties. A limestone-free process of making the clinker provides a 70% reduction of carbon footprint vs. conventional manufacture of Portland cement. Curing the resulting cement in a temperature range from 80° C. to 100° C. advantageously enhances growth of fibrous minerals in the concrete.

The invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm; and blending the milled cement clinker and the supplementary cementitious material; wherein the method is a continuous process comprising the step of calcining the raw material of the supplementary cementitious material in a kiln with a separate heating unit and/or combustion unit. Further, the invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm, wherein at least 5 wt % of the particles have a particle size of above 4.75 mm; and blending the milled cement clinker and the supplementary cementitious material. The invention is also concerns a cement comprising milled cement clinker and a supplementary cementitious material, wherein the supplementary cementitious material comprises an amorphous constituent of more than 30 wt % as measured by XRD, wherein the supplementary cementitious material comprises less than 70 wt % of inert components selected from the group comprising mullite, spinel, feldspar, diopside, mica, or combinations thereof, and wherein the color of the cement in the range of 130-160, 130-160, 120-160, wherein the measurement of the cement color is conducted by a RGB2 colorimeter, wherein the colors are referenced to a RGB scale of 0 to 255.

The invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm; and blending the milled cement clinker and the supplementary cementitious material; wherein the method is a continuous process comprising the step of calcining the raw material of the supplementary cementitious material in a kiln with a separate heating unit and/or combustion unit. Further, the invention is concerned with a method for producing a cement comprising milled cement clinker and a supplementary cementitious material, wherein the method comprises the steps of: producing the milled cement clinker by a clinkerization process, comprising the steps of calcining and subsequently milling a limestone-based raw material; producing the supplementary cementitious material by calcining a raw material of the supplementary cementitious material at a temperature of less than 980° C. and subsequently milling the calcined raw material of the supplementary cementitious material, wherein the raw material of the supplementary cementitious material has an average particle size of 1 to 300 mm, wherein at least 5 wt % of the particles have a particle size of above 4.75 mm; and blending the milled cement clinker and the supplementary cementitious material. The invention is also concerns a cement comprising milled cement clinker and a supplementary cementitious material, wherein the supplementary cementitious material comprises an amorphous constituent of more than 30 wt % as measured by XRD, wherein the supplementary cementitious material comprises less than 70 wt % of inert components selected from the group comprising mullite, spinel, feldspar, diopside, mica, or combinations thereof, and wherein the color of the cement in the range of 130-160, 130-160, 120-160, wherein the measurement of the cement color is conducted by a RGB2 colorimeter, wherein the colors are referenced to a RGB scale of 0 to 255.

A method of processing exhaust gas containing CO.sub.2, such as exhaust gas from a cement production plant, includes burning fuel in the combustion reactor with the O.sub.2 content of the exhaust gas being used as an oxidizing agent, controlling the combustion in the combustion reactor so that the exhaust gas from the combustion reactor contains less than 10 vol.-% of oxygen and at least 80 vol.-% of a mixture of CO and CO.sub.2, and feeding the exhaust gas from the combustion reactor into a conversion reactor, in which the CO.sub.2 and optionally the CO contained in the exhaust gas is converted into a hydrocarbon fuel.

A method of making a cement composite can include contacting an aqueous solution comprising calcium ions with a carbon dioxide source producing a carbonated aqueous solution. Fine particles can be submerged in the carbonated aqueous solution to produce microaggregate particles comprising the fine particles coated with calcium carbonate. The microaggregate particles can be combined with cement particles to produce the cement composite. The cement composite can be used in cementing applications for hydrocarbon wells including for casing liners and well plugs.

Provided herein are compositions, methods, and systems comprising vaterite and magnesium oxide.

Provided herein are compositions, methods, and systems comprising vaterite and magnesium oxide.