Provided herein are integrated biomass combustion-carbonation gas conditioning systems to directly sequester carbon dioxide from biomass-derived CO.sub.2-containing flue gas. The CO.sub.2 is sequestered by mineral carbonation in concrete materials within a carbonation reactor. The mineral carbonation processes sequester CO.sub.2 in concrete materials, aqueous slurries, or aggregates without any additional carbon enrichment process. Contacting a CO.sub.2-containing gas stream from a biomass combustion apparatus with concrete, aggregate, or alkaline solutions, causes a carbonation reaction in which carbonation products such as calcium carbonate (CaCO.sub.3) and alumina silica gel are formed. The carbonation reactions set forth herein are useful for strengthening concrete and concrete components. Certain processes herein condition the biomass-derived flue gas. The conditioning includes condensing the gas to remove acidic gas, and to remove particulates and water. The conditioning includes adjusting the temperature, relative humidity, and gas flow rate of the biomass-derived flue gas without any carbon capture step before entering the carbonation reactor. The permanent storage of CO.sub.2 in concrete materials reduces carbon emissions from biomass combustion systems. The process does so, in certain embodiments, at low temperatures, ambient pressure, and even under dilute CO.sub.2 concentrations in CO.sub.2-containing flue gas streams. For example, the CO.sub.2 concentration in a CO.sub.2-containing flue gas stream from a biomass combustion system may be lower than 20 volume percent (vol %) and be used to produce low-carbon concrete materials.

Provided is a simple and low-cost method for efficiently fixing a sufficient amount of carbon dioxide contained in a carbon dioxide-containing gas (e.g. a plant exhaust gas). The method of fixing carbon dioxide comprises a contact step of bringing a carbon dioxide-containing gas having a temperature of 350° C. or more into contact with a cementitious hardened body to fix carbon dioxide in the carbon dioxide-containing gas to the cementitious hardened body. The carbon dioxide-containing gas may be a gas that is free from being supplied with moisture before the contact step and during the contact step. One of examples of the carbon dioxide-containing gas is a plant exhaust gas.

A method of producing a carbonated composite material includes: providing a carbonatable cementitious material in particulate form; mixing the carbonatable cementitious material with water to produce a mix; forming a predetermined shape with the mix, wherein the predetermined shape has an initial pore structure containing an initial pore solution having a first pH; pre-conditioning the predetermined shape to remove a predetermined amount of the water from the predetermined shape to produce a pre-conditioned shape; carbonating the pre-conditioned shape in an environment comprising carbon dioxide to produce a modified pore structure containing a modified pore solution having and a second pH, wherein the difference between the first pH and the second pH is represented by a ΔpH, and the ΔpH is 1.0 or less.

The disclosure relates to a method for controlling carbonation synthesis of silicon and/or aluminium carbonate minerals, wherein the concentration of dissolved silicon and/or aluminium in a mix to be cured is adjusted to at least 1 mmol/1 before curing he mix with gas comprising carbon dioxide (CO.sub.2) having a partial pressure of CO.sub.2 of at least 0.15 bar. In some embodiments of the isclosure an alkaline substance is added to the raw material to provide the mix where the total concentration of dissolved silicon and/or aluminium of at least 1 mmol/l. The disclosure also relates to a product obtainable by the methods of the disclosure as well as to the use of the product as building material, preferably for producing concrete-like products, more preferably for elements, most preferably for pre-casted elements and to the use of the method in construction industry or for production of elements and/or pre-casted elements.

The present invention relates to a process for providing a fiber cement product, the process comprising the steps of (a) providing an uncured fiber cement product, (b) curing the uncured fiber cement product, (c) optionally abrasive blasting of at least part of the surface of the cured fiber cement product, (d) treating the cured fiber cement product with CO2 (so-called carbonation) at a concentration of 0.01 to 100%, at a temperature of 5 to 90° C., relative humidity of to 99% for a period of 1 minute to 48 hours. The obtained fiber cement products show less efflorescence.

The present invention relates to a process for providing a fiber cement product, the process comprising the steps of (a) providing an uncured fiber cement product, (b) curing the uncured fiber cement product, (c) optionally abrasive blasting of at least part of the surface of the cured fiber cement product, (d) treating the cured fiber cement product with CO2 (so-called carbonation) at a concentration of 0.01 to 100%, at a temperature of 5 to 90° C., relative humidity of to 99% for a period of 1 minute to 48 hours. The obtained fiber cement products show less efflorescence.

To provide a method for producing a calcium carbonate block for medical use which is useful as a bone substitute or a bone substitute raw material needed in medical care, which is a method for producing a calcium carbonate block that satisfies the following desired properties: 1) the calcium carbonate block has excellent mechanical strength; 2) the calcium carbonate block can be produced by a simplified production method; 3) the calcium carbonate block contains no impurity; and 4) the calcium carbonate block has high reactivity. A method for producing a calcium carbonate block, comprising a step of shaping a water-containing calcium hydroxide block and a carbonation step of immersing the calcium hydroxide block in a carbonate ion-containing aqueous solution.

To provide a method for producing a calcium carbonate block for medical use which is useful as a bone substitute or a bone substitute raw material needed in medical care, which is a method for producing a calcium carbonate block that satisfies the following desired properties: 1) the calcium carbonate block has excellent mechanical strength; 2) the calcium carbonate block can be produced by a simplified production method; 3) the calcium carbonate block contains no impurity; and 4) the calcium carbonate block has high reactivity. A method for producing a calcium carbonate block, comprising a step of shaping a water-containing calcium hydroxide block and a carbonation step of immersing the calcium hydroxide block in a carbonate ion-containing aqueous solution.

The invention discloses an artificial nacre material with layered structure and preparation method thereof. The preparation method includes the following steps: uniformly mixing a carbonated cementitious material and water at a water-solid ratio of 0.3 to 1.2 to obtain a carbonated cementitious material suspension; treating the carbonated cementitious material suspension by a freeze-casting process to obtain a carbonated cementitious material coagulation with layered structure; treating the carbonated cementitious material coagulation with the layered structure by a freeze-drying process to obtain a carbonated cementitious material with layered structure; treating the carbonated cementitious material with layered structure by a carbonization process to obtain an artificial nacre material with layered structure. The obtained artificial nacre material with layered structure has higher fracture toughness and durability, and the preparation method has the advantages of low energy consumption, carbon dioxide fixation and environmental friendliness.

A method of producing a carbonated composite material includes: providing a carbonatable cementitious material in particulate form; mixing the carbonatable cementitious material with water to produce a mix; forming a predetermined shape with the mix, wherein the predetermined shape has an initial pore structure containing an initial pore solution having a first pH; pre-conditioning the predetermined shape to remove a predetermined amount of the water from the predetermined shape to produce a pre-conditioned shape; carbonating the pre-conditioned shape in an environment comprising carbon dioxide to produce a modified pore structure containing a modified pore solution having and a second pH, wherein the difference between the first pH and the second pH is represented by a ΔpH, and the ΔpH is 1.0 or less.