Carbonation promoter for hydraulic composition and production method for hydraulic composition hardened product

Abstract

To provide a carbonation promoter for a hydraulic composition, the promoter being capable of promoting the carbonation of a hydraulic composition when added to the hydraulic composition.SOLUTION: There is provided a carbonation promoter for a hydraulic composition, the promoter containing an organic amine compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a carbonation accelerator for a hydraulic composition and a method for producing a hardened body of a hydraulic composition. More specifically, the present invention relates to a carbonation accelerator for a hydraulic composition capable of accelerating the carbonation of the hydraulic composition by adding it to the hydraulic composition, and a method for producing a hardened body of the hydraulic composition.

Background Art

[0002] In recent years, efforts to achieve a decarbonized society such as carbon neutral or carbon negative have been accelerating around the world. For example, in Japan, in 2020, the realization of "carbon neutrality in 2050" was declared, and in 2021, a target was set to reduce greenhouse gas emissions in fiscal year 2030 by 46% (compared to fiscal year 2013).

[0003] Therefore, for example, even in the construction industry, efforts are being made to reduce carbon dioxide (CO2) emissions.

[0004] Specifically, since concrete uses cement that emits a large amount of carbon dioxide during production, it is a material with a very high carbon dioxide emission. Therefore, in order to reduce carbon dioxide emissions, low-carbon cement and low-carbon concrete that reduce the amount of cement used by using industrial by-products such as blast furnace slag fine powder and fly ash are known.

[0005] Also known is precast concrete obtained by curing a concrete mixture obtained by adding γ-C2S (γ-2CaO·SiO2 (sometimes called "γ belite")) to steelmaking slag powder and Portland cement, and carbonating and curing the concrete after demolding (see, for example, Patent Document 1). This precast concrete is a technique in which carbonation accompanying the absorption of carbon dioxide proceeds on the concrete surface, densification occurs in that part, and high durability is achieved.

[0006] Here, in Patent Document 1, carbonation curing is performed to densify concrete and improve its durability. On the other hand, this technology involves the fixation and absorption of carbon dioxide by concrete. That is, in the entire concrete manufacturing process, it can be said that the carbon dioxide emissions are reduced by the amount of carbon dioxide fixed and absorbed by the concrete through carbonation curing. Thus, γ-C2S (γ-2CaO·SiO2) may be used as a technology for reducing, fixing, and absorbing carbon dioxide (CO2).

[0007] Similarly, as one of the efforts towards reducing greenhouse gas emissions, a carbonation accelerator that promotes the carbonation of alkaline earth metal compounds has also been reported (see Patent Document 2).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, there is still room for improvement regarding the amount and rate of carbon dioxide absorption. Therefore, the development of a carbonation accelerator that can further increase the amount of carbon dioxide absorbed and fixed by concrete, improve the carbon dioxide absorption rate, or both is desired. Note that increasing the amount of carbon dioxide absorbed by concrete at a predetermined age will shorten the time until a certain amount of carbon dioxide is absorbed, and as a result, it will also shorten the carbonation curing period (shorten the manufacturing time of concrete products).

[0010] In view of the above circumstances, the present invention aims to provide a carbonation accelerator for hydraulic compositions that can promote the carbonation of the hydraulic composition and reduce the carbon dioxide balance of the hydraulic composition by adding it to the hydraulic composition. The carbon dioxide balance is the amount of carbon dioxide calculated by the formula: "the amount of carbon dioxide derived from the raw materials constituting the concrete (i.e., the amount of carbon dioxide generated during the production of the raw materials)" - "the amount of carbon dioxide absorbed and immobilized by carbonation curing etc.". And "reducing the carbon dioxide balance" means increasing the reduction amount of carbon dioxide and decreasing the value of the carbon dioxide balance calculated by the above formula.

Means for Solving the Problems

[0011] As a result of intensive research to solve the above problems, the present inventors have found that the above problems can be solved by containing an organic amine compound. According to the present invention, the following carbonation accelerator for hydraulic compositions and a method for producing a hardened body of a hydraulic composition are provided.

[0012] [1] A carbonation accelerator for hydraulic compositions, characterized by containing an organic amine compound.

[0013] [2] The carbonation accelerator for hydraulic compositions according to [1] above, wherein the organic amine compound contains at least one selected from alkanolamines and polyamines.

[0014] [3] The carbonation accelerator for hydraulic compositions according to [1] or [2] above, which is added to a hydraulic composition that becomes a hardened body of a hydraulic composition through a carbonation curing step, which is a step of curing in an environment with a volume concentration of carbon dioxide of 5% or more.

[0015] [4] The carbonation accelerator for hydraulic compositions according to [1] or [2] above, which is added to a hydraulic composition containing a binder containing 40 to 99% by mass of blast furnace slag fine powder, water, and aggregate.

[0016] [5] The carbonation accelerator for a hydraulic composition according to the above [1] or [2], wherein the hydraulic composition contains γ-2CaO·SiO2.

[0017] [6] The carbonation accelerator for a hydraulic composition according to the above [1] or [2], wherein the hydraulic composition contains at least one selected from the following CO2-fixing fine powder and the following CO2-fixing modified recycled fine aggregate. CO2-fixing fine powder: The 50% particle size is 50 μm or less, and it contains modified concrete powder which is a reaction product of recycled concrete powder and carbon dioxide gas. The modified concrete powder contains calcium carbonate and silicate. However, the content ratio of the CO2-fixing fine powder in the hydraulic composition is in the range of 1 to 100% by mass with respect to 100% by mass of the binder. CO2-fixing modified recycled fine aggregate: The particle size of all particles is 10 mm or less, and 85% or more of them are 5 mm or less. It contains modified recycled fine aggregate which is a reaction product, either dry or wet, of recycled fine aggregate with a water absorption rate of more than 3.0% and 10% or less and carbon dioxide gas. The modified recycled fine aggregate contains calcium carbonate and silicon dioxide. However, the content ratio of the CO2-fixing modified recycled fine aggregate in the hydraulic composition is in the range of 10 to 100% by volume with respect to the total aggregate volume.

[0018] [7] A preparation step of preparing a hydraulic composition containing the carbonation accelerator for a hydraulic composition according to the above [1] or [2], a binder containing 40 to 99% by mass of blast furnace slag fine powder, and water. A hardening step of hardening the obtained hydraulic composition to obtain a hardened body of the hydraulic composition. A carbonation curing step of curing the obtained hardened body of the hydraulic composition in an environment with a volume concentration of carbon dioxide of 5% or more to absorb and immobilize carbon dioxide in the hardened body of the hydraulic composition. A method for producing a hardened body of a hydraulic composition, characterized by comprising the above steps.

Advantages of the Invention

[0019] The carbonation accelerator for hydraulic compositions of the present invention, when added to a hydraulic composition, promotes the carbonation of the hydraulic composition and can reduce the carbon dioxide balance of the hydraulic composition, having the effect of increasing the amount of carbon dioxide absorbed by the hydraulic composition (i.e., the reduction amount of carbon dioxide).

[0020] According to the method for producing a cured body of a hydraulic composition of the present invention, since a hydraulic composition containing the carbonation accelerator for hydraulic compositions of the present invention is used, it has the effect of increasing the amount of carbon dioxide reduced in the production process.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. Therefore, it should be understood that appropriate changes, improvements, etc. can be made to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. In the following examples, etc., unless otherwise specified, % means mass %, and parts mean parts by mass.

[0022] (1) Carbonation accelerator for hydraulic compositions: The carbonation accelerator for hydraulic compositions of the present invention contains an organic amine compound. This carbonation accelerator for hydraulic compositions, when added to a hydraulic composition, promotes the carbonation of the hydraulic composition and can increase the amount of carbon dioxide absorbed by the hydraulic composition (i.e., the reduction amount of carbon dioxide). That is, the carbon dioxide balance of the hydraulic composition can be reduced.

[0023] Note that calcium silicate hydrate (C-S-H), calcium hydroxide (CH), etc. are generated by the hydration of cement. In addition, the hydraulic composition contains calcium oxide (CaO), etc. derived from its raw materials. And by these compounds undergoing carbonation (reacting with carbon dioxide), carbon dioxide can be absorbed and immobilized in the hydraulic composition (cured body of the hydraulic composition).

[0024] For example, in a thermal power plant or the like, carbon dioxide is released into the atmosphere as exhaust gas. Although this carbon dioxide is considered to be one of the causes of global warming, by supplying the carbon dioxide in the exhaust gas to a carbonation curing process, the carbon dioxide can be absorbed into a hydraulic composition, thereby reducing the carbon dioxide. Note that the hardened body of the hydraulic composition can not only be carbonated and cured, but also be installed at a predetermined location later to immobilize carbon dioxide in the atmosphere for a long time.

[0025] (1-1) Organic amine compound: The organic amine compound is an organic compound containing any one of primary amine, secondary amine, and tertiary amine. By containing this organic amine compound, the amount of carbon dioxide absorbed by the hardened body of the hydraulic composition (that is, the amount of carbon dioxide reduction) can be increased.

[0026] Examples of the organic amine compound include alkanolamine, polyamine, aliphatic amine, aromatic amine, and heterocyclic amine.

[0027] Examples of the organic amine compound include, more specifically, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, methylethanolamine, methylisopropanolamine, methyldiethanolamine, methyldiisopropanolamine, diethanolisopropanolamine, diisopropanol ethanolamine, tetrahydroxyethylethylenediamine, N,N-bis(2-hydroxyethyl)2-propanolamine, N,N-bis(2-hydroxypropyl)-N-(hydroxyethyl)amine, N,N-bis(2-hydroxyethyl)-N-(2-hydroxypropyl)amine, N,N,N’,N’-tetrakis(2-hydroxypropyl)ethylenediamine, tris(2-hydroxybutyl)amine, N,N’-bis(2-hydroxyethyl)ethylenediamine, 2-({2-[(2-aminoethyl)amino]ethyl}amino)ethanol, tris(hydroxymethyl)aminomethane, aminopropanediol, 2-amino-2-ethyl-1,3-propanediol, 2-(dimethylamino)ethanol, 2-methylaminoethanol, 2-(2-aminoethoxy)ethanol, N-phenyldiethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylpiperazine, piperazine, 2-aminophenol, glutamine, morpholine, etc.

[0028] The organic amine compound preferably contains at least one selected from alkanolamines and polyamines. By containing this specific organic amine compound, the amount of carbon dioxide absorbed by the cured body of the hydraulic composition can be further increased.

[0029] When the organic amine compound contains at least one selected from alkanolamines and polyamines, the total proportion thereof can be 10 to 100% by mass in the organic amine compound.

[0030] In addition, in this specification, "alkanolamine" shall mean a compound having an alkane skeleton, a hydroxy group, and an amino group.

[0031] In addition, in this specification, "polyamine" shall mean a hydrocarbon compound having two or more amino groups in the molecule.

[0032] Specific examples of the alkanolamine and polyamine include triisopropanolamine, 1,2-bis{di(hydroxyethyl)amino}ethane, N,N'-bis(2-hydroxyethyl)ethylenediamine, diethanolamine, diisopropanolamine, 2-({2-[(2-aminoethyl)amino]ethyl}amino)ethanol, tris(hydroxymethyl)aminomethane, aminopropanediol, diethylenetriamine, triethylenetetramine, triethanolamine, etc., and it is preferable to contain at least one or more of these.

[0033] The content ratio of the organic amine compound is not particularly limited, but for example, it can be 10 to 100% by mass, preferably 15 to 100% by mass, and more preferably 20 to 100% by mass. That is, the content ratio of components other than the organic amine compound is not particularly limited, but it is preferably less than a predetermined ratio. By setting such a range, when the "component other than the organic amine compound" is other than water, when the carbonation accelerator for the hydraulic composition is added to the hydraulic composition, it is possible to avoid the addition amount of the "component other than the organic amine compound" from becoming too large, and it is possible to reduce the concern that the "component other than the organic amine compound" affects various physical properties of the hydraulic composition. Further, when the "component other than the organic amine compound" is water (that is, in the case of an aqueous solution of the organic amine compound), by setting the above content ratio, the product stability of the carbonation accelerator for the hydraulic composition is easily maintained. Also, it becomes easier to measure when using the carbonation accelerator for the hydraulic composition. That is, when adding the carbonation accelerator for the hydraulic composition to the hydraulic composition, the carbonation accelerator for the hydraulic composition is added so that the organic amine compound reaches the required concentration. By setting the above content ratio, the addition amount (handling amount) of the carbonation accelerator for the hydraulic composition can be reduced, and the labor of measurement is reduced.

[0034] (1-2) Other components: The carbonation accelerator for the hydraulic composition of the present invention can contain other components in addition to the above organic amine compound as long as the effects are not impaired.

[0035] As other components, for example, water or additives added to conventionally known hydraulic compositions can be appropriately selected and employed.

[0036] Note that the other components may be used alone or in combination of two or more.

[0037] The carbonation accelerator for the hydraulic composition of the present invention is preferably added to the hydraulic composition described later.

[0038] (2) Hydraulic composition: The carbonation accelerator for hydraulic compositions of the present invention can be added to and used in hydraulic compositions. This hydraulic composition can include a binder (hydraulic binder), water, and aggregates (fine aggregates, coarse aggregates) in the same manner as conventionally known hydraulic compositions.

[0039] There is no particular limitation on the content ratio of the carbonation accelerator for hydraulic compositions of the present invention in the hydraulic composition, and it can be appropriately set. For example, the content ratio of the carbonation accelerator for hydraulic compositions of the present invention can be 0.001 to 5% by mass based on 100% by mass of the binder.

[0040] Examples of the binder include various Portland cements such as ordinary Portland cement, medium heat Portland cement, low heat Portland cement, early strength Portland cement, sulfate resistant Portland cement, and various cements such as blast furnace cement, fly ash cement, and silica fume cement.

[0041] Furthermore, as the binder, various admixtures such as fly ash, blast furnace slag fine powder, limestone fine powder, stone powder, silica fume, expansive agent, anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum may be used in combination with the above-mentioned various cements.

[0042] Note that the binder preferably contains 40 to 99% by mass of blast furnace slag fine powder. That is, the hydraulic composition to which the carbonation accelerator for hydraulic compositions of the present invention is added preferably contains a binder containing 40 to 99% by mass of blast furnace slag fine powder, water, and aggregates. The content ratio of the blast furnace slag fine powder is preferably 50 to 99% by mass, and more preferably 60 to 99% by mass. By doing so, the carbon dioxide balance of the hydraulic composition can be further reduced.

[0043] Examples of the aggregates include fine aggregates and coarse aggregates.

[0044] Examples of fine aggregates include river sand, mountain sand, land sand, sea sand, silica sand, crushed sand, various slag fine aggregates, various recycled fine aggregates, etc., and those containing fine components such as clay may also be used.

[0045] Examples of coarse aggregates include river gravel, mountain gravel, land gravel, crushed stone, various slag coarse aggregates, lightweight aggregates, various recycled coarse aggregates, etc.

[0046] The hydraulic composition preferably contains γ-2CaO·SiO2. That is, the carbonation accelerator for the hydraulic composition of the present invention is preferably added to a hydraulic composition containing γ-2CaO·SiO2. By doing so, since γ-2CaO·SiO2 exhibits the function of immobilizing carbon dioxide, the amount of carbon dioxide absorbed by the hardened body of the hydraulic composition (i.e., the amount of carbon dioxide reduction) can be further increased. As a result, the carbon dioxide balance of the hydraulic composition can be further reduced. This γ-2CaO·SiO2 is a material that hardens by carbonation. Note that γ-2CaO·SiO2 may be added to a hydraulic composition containing a binder containing 40 to 99% by mass of blast furnace slag fine powder, water, and aggregates, or to a hydraulic composition not containing these binders.

[0047] The content ratio of γ-2CaO·SiO2 is not particularly limited, but for example, it can be set to a ratio corresponding to 1 to 30% by mass on an internal basis with respect to 100% by mass of the binder.

[0048] The hydraulic composition preferably contains at least one selected from the following CO2-fixing fine powder and the following CO2-fixing modified recycled fine aggregate. By doing so, the carbon dioxide balance of the hydraulic composition can be further reduced. Incidentally, CCU (Carbon Capture and Utilization) materials such as CO2-fixing fine powder and CO2-fixing modified recycled aggregate (including CO2-fixing modified recycled fine aggregate) are powders and aggregates produced by previously reacting CO2 with calcium components derived from waste such as waste concrete, and the CCU material may be used for carbon-neutral or carbon-negative concrete. In addition to the CO2-fixing modified recycled fine aggregate, a CO2-fixing modified recycled coarse aggregate may be further adopted in the hydraulic composition, or a CO2-fixing modified recycled coarse aggregate may be adopted instead of the CO2-fixing modified recycled fine aggregate.

[0049] (CO2-fixing fine powder) The CO2-fixing fine powder has a 50% particle size of 50 μm or less and contains a modified concrete powder that is a reaction product of recycled concrete powder and carbon dioxide gas. This modified concrete powder contains calcium carbonate and silicate. And the content ratio of the CO2-fixing fine powder is in the range of 1 to 100% by mass with respect to 100% by mass of the binder.

[0050] The CO2-fixed fine powder can be produced as follows. First, the concrete block is crushed or ground, and recycled concrete fine powder with a median diameter of 100 μm or less is recovered. There are no particular restrictions on the method of crushing or grinding, and known crushing or grinding devices such as shot blasting-type crushing devices, impact crushers, and grinding devices such as mechanical rubbing methods without heating can be used. Next, the recovered recycled concrete fine powder is reacted with carbon dioxide gas at a volume concentration of 5% or more to fix CO2 to the cement-derived components contained in the recycled concrete fine powder. The reaction with carbon dioxide gas may be a dry method in which gaseous carbon dioxide gas is brought into contact, or a wet method in which the recycled concrete fine powder is immersed in a solution such as water and then carbon dioxide gas is blown into this liquid (dispersion) to bring it into contact. In this way, the CO2-fixed fine powder can be produced.

[0051] (CO2-fixed modified recycled aggregate) CO2-fixed modified recycled aggregate is an aggregate produced by previously reacting CO2 with calcium components derived from waste such as waste concrete. Examples include CO2-fixed modified recycled fine aggregate and CO2-fixed modified recycled coarse aggregate. Among these, it contains more cement-derived calcium components, has a larger CO2 fixation amount during the production of CO2-fixed modified recycled aggregate (i.e., the "emission amount of carbon dioxide derived from the material" is small), and has a large reduction effect on the carbon dioxide balance when applied to a hydraulic composition. Therefore, it is preferable to use CO2-fixed modified recycled fine aggregate.

[0052] (CO2-fixed modified recycled fine aggregate) CO2-fixed modified recycled fine aggregate includes modified recycled fine aggregate, which is a reaction product of recycled fine aggregate with all particle diameters of 10 mm or less, 85% or more of which are 5 mm or less and the water absorption rate is more than 3.0% and 10% or less, and carbon dioxide gas, in a dry or wet manner. The modified recycled fine aggregate contains calcium carbonate and silicon dioxide. The content ratio of CO2-fixed modified recycled fine aggregate is in the range of 10 to 100 volume% with respect to the total aggregate volume.

[0053] The CO2-fixed modified recycled fine aggregate can be manufactured as follows. That is, first, the concrete block is crushed or ground to obtain recycled fine aggregate. Note that there is no particular limitation on the method of performing this crushing or grinding, and known crushing devices or grinding devices such as shot blasting type crushing devices, impact crushers, and grinding devices such as mechanical rubbing methods without heating can be used. Then, particles with a particle size of 10 mm or less for all particles are classified, and among them, particles with a water absorption rate exceeding 3% and not exceeding 10% are used as recycled fine aggregate. Next, the recycled fine aggregate is reacted with carbon dioxide gas at a volume concentration of 5% or more to obtain a CO2-fixed modified recycled fine aggregate containing calcium carbonate and silicon dioxide. The reaction between the recycled fine aggregate and carbon dioxide gas may adopt a dry method or a wet method. In this way, the CO2-fixed modified recycled fine aggregate can be manufactured.

[0054] The content ratio of the CO2-fixed fine powder is 1 to 100 mass%, preferably 10 to 90 mass%, and more preferably 30 to 80 mass% with respect to 100 mass% of the binder as described above.

[0055] The content ratio of the CO2-fixed modified recycled fine aggregate is 10 to 100 volume%, preferably 20 to 100 volume%, and more preferably 30 to 100 volume% with respect to the total aggregate volume (more specifically, the aggregate volume using the original blended natural aggregate) as described above.

[0056] Here, the original mixture refers to a mixture that does not use CO2-fixed modified recycled fine aggregates. Also, natural aggregates refer to aggregates that have not undergone CO2 fixation treatment. For example, in the case of fine aggregates, it includes river sand, mountain sand, land sand, sea sand, silica sand, crushed sand, various slag fine aggregates, etc. In the case of coarse aggregates, it includes, for example, river gravel, mountain gravel, land gravel, crushed stone, various slag coarse aggregates, lightweight aggregates, etc. That is, "with respect to the aggregate volume using the natural aggregates of the original mixture" means with respect to the volume of natural aggregates such as river sand as in the past. That is, conventionally, CO2-fixed modified recycled fine aggregates may be used instead of what was used as aggregates (100% by volume), or about 1 / 5 (i.e., 20% by volume) may be replaced and used.

[0057] The hydraulic composition may further contain other constituent components as appropriate within a range where the effects are not impaired. Examples of such other constituent components include sugar, a setting retarder component composed of oxycarboxylate, etc., a component having a dispersing action composed of sodium lignosulfonate, etc., an antifoaming agent composed of an oxyalkylene-based compound, etc., a shrinkage reducing agent composed of polyoxyalkylene alkyl ether, etc., a thickening agent composed of a cellulose ether-based compound, etc., a preservative composed of an isothiazoline-based compound, etc., a rust preventive composed of nitrite, etc.

[0058] As the content ratio of other constituent components, for example, it can be 0 to 5% by mass with respect to 100% by mass of the binder.

[0059] As the ratio of water to binder (water / binder ratio) of the hydraulic composition, a conventionally known ratio can be appropriately adopted. For example, it can be 25 to 70% by mass.

[0060] The hydraulic composition can be cured to form a cured body of the hydraulic composition (specifically, mortar or concrete). When obtaining such a cured body of the hydraulic composition, it is preferable to go through a carbonation curing process, which is a process of curing in an environment with a volume concentration of carbon dioxide of 5% or more. By going through such a carbonation curing process, a large amount of carbon dioxide can be absorbed and immobilized in the hydraulic composition (cured body of the hydraulic composition).

[0061] Note that the volume concentration of carbon dioxide in the carbonation curing process is not particularly limited, but it can usually be set to 5 - 100%.

[0062] (3) Method for manufacturing a cured body of a hydraulic composition: The method for manufacturing a cured body of the hydraulic composition of the present invention includes a preparation step of preparing a hydraulic composition containing a carbonation accelerator for the hydraulic composition of the present invention, a binder containing 40 - 99% by mass of fine blast furnace slag powder, and water, a curing step of curing the obtained hydraulic composition to obtain a cured body of the hydraulic composition, and a carbonation curing step of curing the obtained cured body of the hydraulic composition in an environment with a volume concentration of carbon dioxide of 5% or more to absorb and immobilize carbon dioxide in the cured body of the hydraulic composition. According to such a method for manufacturing a cured body of a hydraulic composition, since a hydraulic composition containing the carbonation accelerator for the hydraulic composition of the present invention is used, the amount of carbon dioxide reduced in the manufacturing process increases.

[0063] (3 - 1) Preparation step: The preparation step is a step of preparing a hydraulic composition containing a carbonation accelerator for the hydraulic composition of the present invention, a binder containing 40 - 99% by mass of fine blast furnace slag powder, and water.

[0064] The fine blast furnace slag powder is contained at 40 - 99% by mass as described above, preferably 50 - 99% by mass, and more preferably 60 - 99% by mass. By setting the above content ratio, the amount of carbon dioxide reduced in the manufacturing process of the cured body of the hydraulic composition increases.

[0065] (3 - 2) Curing step: The hardening process is a process of hardening the hydraulic composition obtained in the preparation process to obtain a hardened body of the hydraulic composition. As the method for hardening the hydraulic composition, a conventionally known method can be appropriately adopted.

[0066] (3-3) Carbonation curing process: The carbonation curing process is a process of curing the hardened body of the hydraulic composition obtained in the hardening process in an environment with a volume concentration of carbon dioxide of 5% or more (carbonation curing) to absorb and immobilize carbon dioxide in the hardened body of the hydraulic composition.

[0067] In this process, carbon dioxide in the atmosphere is absorbed by the hardened body of the hydraulic composition, carbonated, and fixed. By using the carbonation accelerator for the hydraulic composition of the present invention, more carbon dioxide can be absorbed and immobilized in the hydraulic composition (hardened body of the hydraulic composition).

[0068] The volume concentration of carbon dioxide is not particularly limited, but it can usually be 5 to 100%.

[0069] If the volume concentration of carbon dioxide is less than 5%, the amount of carbon dioxide absorbed is too small, and the period until a predetermined carbon dioxide fixation amount is reached may be prolonged.

Examples

[0070] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0071] (Examples 1 to 86, Comparative Examples 1 to 9) (1) Carbonation accelerator for hydraulic composition: First, carbonation accelerators A-1 to A-22 and RA-1 to RA-2 for the hydraulic composition of the examples and comparative examples were prepared with the formulations shown in Table 1 below. Each of the organic amine compounds A-1 to A-22, the organic amine compounds A-1 to A-9, A-12 to A-19 are alkanolamines, and the organic amine compounds A-10 to A-11 are polyamines.

[0072]

Table 1

[0073] The manufacturing methods of carbonation accelerators A-2 and A-6 for each hydraulic composition will be specifically described below. For carbonation accelerators for hydraulic compositions other than A-2 and A-6 for hydraulic compositions, those of the above manufacturers were used.

[0074] Note that RA-1 in Table 1 is calcium nitrate tetrahydrate, which is a compound conventionally used as a hardening accelerator for hydraulic compositions. RA-2 in Table 1 is calcium nitrite monohydrate, which is a compound conventionally used as a hardening accelerator for hydraulic compositions.

[0075] Organic amine compound A-2: First, 254.3 g of ethylenediamine was charged into a pressure vessel equipped with a stirrer, a pressure gauge, and a thermometer. Then, while maintaining the reaction system at 85 ± 10 °C, 745.7 g of ethylene oxide was added at a gauge pressure of 0.4 MPa over 4 hours, and the reaction was terminated by holding at 85 ± 10 °C for 2 hours. Then, the reaction solution was filtered to obtain 1,2-bis{di(hydroxyethyl)amino}ethane (organic amine compound A-2).

[0076] Organic amine compound A-6: First, 701.0 g of diethylenetriamine was charged into a pressure vessel equipped with a stirrer, a pressure gauge, and a thermometer. Then, while maintaining the reaction system at 85 ± 10 °C, 299.0 g of ethylene oxide was added at a gauge pressure of 0.4 MPa over 4 hours, and the reaction was terminated by holding at 85 ± 10 °C for 2 hours. Then, the reaction solution was filtered to obtain 2-({2-[(2-aminoethyl)amino]ethyl}amino)ethanol (organic amine compound A-6).

[0077] (2) Hydraulic composition: Next, hydraulic compositions (mortars) were prepared using the formulations C-1 to C-3 shown in Table 2.

[0078] Specifically, first, into the kneader specified in JIS R5201, with the formulations C-1 to C-3 (mortar formulations) shown in Table 3, ordinary Portland cement (manufactured by Taiheiyo Cement Corporation, density 3.16 g / cm 3 ), blast furnace slag fine powder #4000 (manufactured by Cement Central Co., Ltd., density 2.89 g / cm 3 ), carbonation admixture LEAF mainly composed of γ-2CaO·SiO2 (manufactured by Denka Co., Ltd., density 3.09 g / cm 3 ), fine aggregate (Oigawa River system land sand, density 2.58 g / cm 3 ), carbon dioxide (CO2) fixation fine powder (CCU fine powder; density 2.51 g / cm 3 ), and carbon dioxide (CO2) fixation modified recycled aggregate (CCU recycled fine aggregate; density 2.42 g / cm 3 ) were sequentially charged, and then dry kneaded for 10 seconds. Here, ordinary Portland cement, blast furnace slag fine powder, and the carbonation admixture were regarded as binders.

[0079] The CO2 fixation fine powder and the CO2 fixation modified recycled aggregate are specifically shown below.

[0080] The CO2 fixation fine powder has a particle size of 50 μm or less for 50% of the particles, contains modified concrete powder which is a reaction product of recycled concrete powder and carbon dioxide gas, and contains calcium carbonate and silicate.

[0081] This CO2 fixation fine powder was specifically manufactured as follows. That is, concrete blocks were crushed and ground by a known crusher to obtain recycled concrete fine powder with a median diameter of 100 μm or less. Subsequently, 1800 kg of water and 200 kg of the obtained recycled concrete fine powder were sequentially charged into a container with a capacity of 2 m 3 and stirred, and further, carbon dioxide gas was injected from the bottom of the container at a rate of 150 L / min to react the recycled concrete fine powder with CO2. The above reaction treatment was continued until the pH of the dispersion became 6.8 or less, and then a reaction product of the recycled concrete fine powder and CO2 was obtained. After the reaction was completed, the obtained reaction product was taken out, excess moisture was removed with a polypropylene twill filter, and then air-dried to obtain the CO2 fixation fine powder.

[0082] The CO2-fixing modified recycled aggregate (specifically, CO2-fixing modified recycled fine aggregate) contains a modified recycled fine aggregate which is a dry or wet reaction product of a recycled fine aggregate with a water absorption rate exceeding 3.0% and not exceeding 10% and carbon dioxide gas, and contains calcium carbonate, silicon dioxide and gypsum.

[0083] This CO2-fixing modified recycled aggregate was specifically manufactured as follows. That is, the concrete block was crushed and ground by a known crusher, and then sieved and classified so that all particle diameters of the particles became particles with a particle diameter of 10 mm or less. Among them, particles with a water absorption rate exceeding 3% and not exceeding 10% were obtained as recycled fine aggregates. Subsequently, 1800 kg of water and 200 kg of the obtained recycled fine aggregate were sequentially charged into a container with a volume of 2 m 3 and stirred, and further, carbon dioxide gas was injected from the bottom of the container at a rate of 150 L / min to react the recycled fine aggregate with CO2. The above reaction treatment was continued until the pH of the dispersion became 6.8 or less, and then a reaction product of the recycled fine aggregate and CO2 was obtained. After the reaction was completed, the obtained reaction product was taken out, excess moisture was removed with a polypropylene twill filter, and then air-dried to obtain a CO2-fixing modified recycled fine aggregate.

[0084] Next, a carbonation accelerator for the hydraulic composition shown in Table 1, a water reducing agent (high-performance water reducing agent Chupol NV-80 (trade name) manufactured by Takemoto Yushi Co., Ltd.), and an antifoaming agent (AFK-2 (trade name) manufactured by Takemoto Yushi Co., Ltd.) were kneaded and added to water (however, the above carbonation accelerator, water reducing agent and antifoaming agent are regarded as a part of the water). Then, this kneaded water was put into a kneader and kneaded for 180 seconds to obtain a hydraulic composition (mortar).

[0085] In addition, the carbonation accelerator for the hydraulic composition was added in the range of 0.02 to 0.20% by mass based on the binder as shown in Tables 3 to 5. Further, the addition amount of the water reducing agent was such that the mortar flow was within 205 ± 5 mm for Mix C-1, within 200 ± 5 mm for Mix C-2, and within 275 ± 5 mm for Mix C-3. Also, the antifoaming agent was added after adjusting so that the air content of the mortar after kneading was 2% or less.

[0086]

Table 2

[0087] Regarding Mix C-1 to C-3, the following relationships exist. Specifically, no carbonation admixture was used in Mix C-1, while carbonation admixtures were used in Mix C-2 and C-3. This carbonation admixture is 30% by mass based on the binder. In Mix C-3, CCU fine powder was blended, and this CCU fine powder replaced 50% by mass of the fine aggregate outside the binder. Also, in Mix C-3, CCU recycled fine aggregate was blended, and 100% of the fine aggregate was replaced with this CCU recycled fine aggregate.

[0088] In Table 2, the "emission amount of carbon dioxide from materials (α)" was calculated based on the carbon dioxide emission amounts of each component. That is, the carbon dioxide emission amount of ordinary Portland cement is 764.3 kg / t, the carbon dioxide emission amount of blast furnace slag fine powder is 26.5 kg / t, the carbon dioxide emission amount of the carbonation admixture is 124.5 kg / t, the carbon dioxide emission amount of CCU recycled fine aggregate is -26.9 kg / t, and the carbon dioxide emission amount of CCU fine powder is -83.8 kg / t.

[0089] Tables 3 to 5 show the test results (mortar flow (mm), air content (%)) of the mortar prepared using each of Mix C-1 to C-3, and the results of carbon dioxide balance, etc. Note that the numerical values in the column of "emission amount of carbon dioxide from materials (α)" in Tables 3 to 5 are the "emission amount of carbon dioxide from materials (α)" shown in Table 2.

[0090] In Examples 1 to 28 and Comparative Examples 1 to 2 shown in Table 3, based on the carbon dioxide balance of Comparative Example 3, the difference from the carbon dioxide balance in each example and comparative example was calculated, and the value of the "carbon dioxide reduction amount" by the carbonation accelerator for the hydraulic composition was shown. In Examples 29 to 57 and Comparative Examples 4 to 5 shown in Table 4, based on the carbon dioxide balance of Comparative Example 6, the difference from the carbon dioxide balance in each example and comparative example was calculated, and the value of the "carbon dioxide reduction amount" by the carbonation accelerator for the hydraulic composition was shown. In Examples 58 to 86 and Comparative Examples 7 to 8 shown in Table 5, based on the carbon dioxide balance of Comparative Example 9, the difference from the carbon dioxide balance in each example and comparative example was calculated, and the value of the "carbon dioxide reduction amount" by the carbonation accelerator for the hydraulic composition was shown.

[0091] Here, in Comparative Examples 3, 6, and 9, only a water reducing agent was used without using a carbonation accelerator for the hydraulic composition.

[0092] The measuring methods of the mortar flow (mm) and the air content (%) for the hydraulic composition are shown below.

[0093] (Mortar flow) For the hydraulic composition immediately after mixing, it was measured in a state without free fall in accordance with JIS R5201.

[0094] (Air content (volume %)) For the hydraulic composition immediately after mixing, it was measured using a container for mortar in accordance with JIS A1116.

[0095] (3) Method for manufacturing a hardened body of the hydraulic composition: (Hardening process of mortar) First, a formwork of a cylindrical tin concrete specimen mold (trade name "Summit Mold", Sumisho Cement, the diameter of the bottom surface of the mold is 50 mm, and the height of the mold is 100 mm) was prepared, and the prepared hydraulic composition (mortar) was filled into this formwork by adopting a two-layer filling method.

[0096] Next, the mortar was cured in air (20°C) in a room at 20°C. Then, 2 hours after the preparation of the mortar, the surface of the filled mortar was smoothed, and polyethylene wrap was placed over it to prevent water from evaporating, and sealed curing was performed until the material reached an age of 2 days. Then, a test specimen (hardened mortar) was obtained.

[0097] (Carbonation curing process of hardened mortar (hardened hydraulic composition)) After the sealed curing, the test specimen (hardened mortar body) was removed from the formwork and carbonation cured in a high-concentration accelerated carbonation curing tank (manufactured by Marui Co., Ltd.) capable of controlling temperature, humidity and carbon dioxide concentration until the material was 7 days old (curing conditions: 20°C, 60% RH, carbon dioxide volume concentration 60%). At this time, the test specimen was not covered, and carbonation was carried out from the entire surface of the test specimen. In this way, a hydraulic composition hardened body was produced.

[0098] (Measurement of the amount of fixed carbon dioxide) For the produced hydraulic composition hardened product, the amount of fixed carbon dioxide was measured as follows.

[0099] (Method of preparing analytical samples) After carbonation curing, the test specimen (hardened hydraulic composition) was removed from the curing tank and quickly moved to a furnace at 105°C for drying treatment for two days. After drying, the test specimen was completely crushed and further pulverized in a ball mill to 150 μm or less, and this was used as the analysis sample.

[0100] (Method of measuring total carbon amount, method of calculating amount of CO2 fixed by carbonation curing) In order to confirm the amount of carbon dioxide fixed (CO2 fixed amount) by carbonation curing, the total carbon amount (C (%)) in the analytical sample was measured using a total organic carbon meter ("TOC-L" and solid sample combustion device "SSM-5000A" manufactured by Shimadzu Corporation). The measurement conditions were a sample amount of 50 mg and a combustion temperature of 900°C.

[0101] From the total carbon content obtained, the amount of CO2 fixed (%) in the analytical sample was calculated using the following formula, and the amount of carbon dioxide fixed by carbonation curing (kg-CO2 / m 3 ) was calculated. Formula: CO2(%) = C(%) × 44 / 12

[0102] Note that the amount of CO2 fixation is the ratio to the weight of the sample after heat treatment at 900°C. Also, the amount of carbon detected from the materials used in the mortar (cement, blast furnace slag fine powder, carbonation admixture, CO2-fixing fine powder, fine aggregate, CO2-fixing modified recycled aggregate (CO2-fixing modified recycled fine aggregate)) and the added components (water reducing agent, defoaming agent, carbonation accelerator for hydraulic composition) is subtracted, and the amount of CO2 fixation by carbonation curing is calculated.

[0103] In Tables 3 to 5, "CO2 balance (α-β)" is a value calculated by the formula: emissions of CO2 from materials (α) - amount of CO2 fixation by carbonation curing (β). Also, "amount of CO2 reduction" is a value calculated by the formula: |"CO2 balance" of each example - "CO2 balance" of Comparative Examples 3, 6, and 9|. From the results of this "amount of CO2 reduction", it can be seen that in each example, the CO2 absorption effect is excellent compared to the case of Comparative Examples 3, 6, and 9 which are the benchmarks. That is, in each example, the carbonation of the hydraulic composition is promoted by the carbonation accelerator for the hydraulic composition.

[0104]

Table 3

[0105] Note that in Table 3, the evaluation of the "amount of CO2 reduction" was based on the following evaluation criteria. S: Amount of CO2 reduction (kg-CO2 / m 3 ) is 45 kg-CO2 / m 3 or more A: Amount of CO2 reduction (kg-CO2 / m 3 ) is 35 kg-CO2 / m 3 or more and less than 45 kg-CO2 / m 3 B: Amount of CO2 reduction (kg-CO2 / m 3 ) is 25 kg-CO2 / m 3 or more and less than 35 kg-CO2 / m​3 When it is less than C: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is less than 25 kg-CO2 / m 3 When it is less than

[0106]

Table 4

[0107] In addition, in Table 4, the evaluation of "reduction amount of carbon dioxide" was based on the following evaluation criteria. S: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 40 kg-CO2 / m or more 3 When it is the case A: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 30 kg-CO2 / m or more 3 and less than 40 kg-CO2 / m 3 When it is less than B: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 20 kg-CO2 / m or more 3 and less than 30 kg-CO2 / m 3 When it is less than C: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is less than 20 kg-CO2 / m 3 When it is less than

[0108]

Table 5

[0109] In addition, in Table 5, the evaluation of "reduction amount of carbon dioxide" was based on the following evaluation criteria. S: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 30 kg-CO2 / m or more 3 When it is the case A: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 20 kg-CO2 / m or more 3 and less than 30 kg-CO2 / m 3 When it is less than B: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is 10 kg-CO2 / m 3 or more and less than 20 kg-CO2 / m 3 In the case C: Reduction amount of carbon dioxide (kg-CO2 / m 3 ) is less than 10 kg-CO2 / m 3 In the case

[0110] (Result) As shown in Tables 3 to 5, by adding the carbonation accelerator for the hydraulic composition of this example, it can be seen that the carbonation of the hydraulic composition is promoted and the reduction amount of carbon dioxide by the hydraulic composition (hydraulic composition hardened body) can be increased. Further, according to the manufacturing method of the hardened body of the hydraulic composition of this example, by adopting the carbonation accelerator for the hydraulic composition of this example as a raw material, it can be seen that the carbonation of the hydraulic composition is promoted and the amount of carbon dioxide absorbed by the manufactured hardened body of the hydraulic composition (reduction amount of carbon dioxide) can be increased.

Industrial Applicability

[0111] The carbonation accelerator for the hydraulic composition of the present invention can be used as a raw material for a hardened body of a hydraulic composition that reduces carbon dioxide by adding it to the hydraulic composition. The manufacturing method of the hardened body of the hydraulic composition of the present invention can be adopted as a manufacturing method of a hardened body of a hydraulic composition that absorbs carbon dioxide.

Claims

1. A carbonation accelerator for a hydraulic composition, characterized by containing an organic amine compound.

2. The carbonation accelerator for a hydraulic composition according to Claim 1, wherein the organic amine compound contains at least one selected from alkanolamine and polyamine.

3. The carbonation accelerator for a hydraulic composition according to Claim 1 or 2, which is added to a hydraulic composition that becomes a hardened body of the hydraulic composition through a carbonation curing step, which is a curing step carried out in an environment where the volume concentration of carbon dioxide is 5% or more.

4. The carbonation accelerator for a hydraulic composition according to Claim 1 or 2, which is added to a hydraulic composition containing a binder containing 40 to 99% by mass of fine blast furnace slag powder, water, and aggregate.

5. The hydraulic composition contains γ-2CaO·SiO ２ The carbonation accelerator for a hydraulic composition according to claim 1 or 2, which contains ２ .

6. The hydraulic composition is the following CO ２ fixed fine powder and the following CO ２ The carbonation accelerator for a hydraulic composition according to claim 1 or 2, which contains at least one selected from fixed modified recycled fine aggregates. CO ２ Fixed fine powder: It contains modified concrete powder, which is a reaction product of recycled concrete powder and carbon dioxide gas, with a 50% particle size of 50 μm or less. The modified concrete powder contains calcium carbonate and silicate. However, the content ratio of the CO in the hydraulic composition ２ of the fixed fine powder is in the range of 1 to 100% by mass with respect to 100% by mass of the binder. CO ２ Fixed modified recycled fine aggregate: The particle size of all particles is 10 mm or less, and 85% or more of them are 5 mm or less. It contains modified recycled fine aggregate, which is a reaction product of recycled fine aggregate with a water absorption rate of more than 3.0% and 10% or less and carbon dioxide gas, either dry or wet. The modified recycled fine aggregate contains calcium carbonate and silicon dioxide. However, the content ratio of the CO in the hydraulic composition ２ of the fixed-modified recycled fine aggregate is in the range of 10 to 100% by volume with respect to the total aggregate volume.

7. A preparation step of preparing a hydraulic composition containing the carbonation accelerator for a hydraulic composition according to Claim 1 or 2, a binder containing 40 to 99% by mass of fine blast furnace slag powder, and water; A hardening step of hardening the obtained hydraulic composition to obtain a hardened body of the hydraulic composition; A carbonation curing step of curing the obtained hardened body of the hydraulic composition in an environment where the volume concentration of carbon dioxide is 5% or more to absorb and immobilize carbon dioxide in the hardened body of the hydraulic composition. A method for manufacturing a hardened body of a hydraulic composition, characterized by comprising the above steps.

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