Calcined products, hydraulic compositions, and carbonated hardened products

Abstract

To provide a fired product that can effectively utilize waste such as biomass ash, a hydraulic composition using the fired product, and a carbonated hardening product obtained by carbonating a hardening product of the hydraulic composition capable of greatly reducing a total amount of emission of carbon dioxide due to a large amount of absorption of carbon dioxide in a curing process, and in addition, having the same or less reduction ratio in a strength (e.g., a compressive strength of mortar) compared to a cement hardening product produced conventionally.SOLUTION: The fired product of the present invention contains belite and rankinite, in which the amount of rankinite is 25 to 500 pts.mass with respect to 100 pts.mass of belite, and a mineral represented by the following chemical formula (1) is not contained, or the mineral is contained and the amount of the mineral is 60 pts.mass or less with respect to 100 pts.mass of a total amount of belite and rankinite. 2CaO (Al2O3)x (Fe2O3)1-x SiO2 (1) (X is a number from 0 to 1, in the chemical formula (1)).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to calcined products, hydraulic compositions, and carbonated hardened products. [Background technology]

[0002] In recent years, there has been a growing demand for the effective utilization of waste materials such as biomass ash (biomass incineration ash) and construction-generated soil. One way to effectively utilize the biomass ash mentioned above is to use it directly as a cement admixture. However, because biomass ash contains large amounts of alkali metals and chlorine, it is difficult to use it directly as a cement admixture. As a method for modifying biomass to exhibit high quality as a raw material for cement, for example, Patent Document 1 describes a biomass modification method characterized by comprising a slurry step of adding water to biomass ash to make a slurry, a water washing step of washing the slurry with water, and a dewatering step of dewatering the water-washed slurry. Furthermore, as a method for efficiently removing alkali metals from alkali metal-containing materials such as woody biomass ash, Patent Document 2 describes a method for removing alkali metals from alkali metal-containing materials, comprising: a heat treatment step in which solid alkali metal-containing materials are combined with solid chlorine-containing materials, and the mixture is heated to form alkali metal chlorides, which are then fixed as a solid phase within the heat-treated material; an alkali metal elution step in which water is added to the heat-treated material produced in the heat treatment step to form a slurry, and the alkali metals of the chlorides contained in the heat-treated material are eluted into the liquid phase within the slurry; and a solid-liquid separation step in which the slurry that has undergone the alkali metal elution step is separated into a cake and a filtrate.

[0003] On the other hand, reducing carbon dioxide emissions is currently a crucial issue in order to curb global warming. One known method for reducing carbon dioxide emissions in the production of cementitious hardened bodies is to absorb carbon dioxide during the curing process of the cementitious hardened body, thereby reducing the total amount of carbon dioxide emitted until the cementitious hardened body is obtained. For example, Patent Document 3 describes a precast concrete mixture that has been hardened, in which one or two types of powder components, namely γ-C2S (symbol γ) and steelmaking slag powder (symbol B), and Portland cement (symbol C), and the total amount of γ and B in relation to the total content of γ, B, and C is 25 to 95% by mass, and the water-cement ratio (W / C) is 80 to 250%, and the mixture undergoes carbonation curing during the hardening process, thereby forming a carbonation region in the area from the surface to a depth of 20 mm or more (however, in the area with a wall thickness of less than 20 mm, the entire wall thickness), thereby absorbing CO2. This precast concrete can significantly reduce the total amount of carbon dioxide emitted when manufacturing concrete products by utilizing the absorption of carbon dioxide during carbonation curing.

[0004] Furthermore, Patent Document 4 describes a cementitious hardened body characterized by carbonizing a cement mixture containing (A) pulverized calcined material having 10 to 200 parts by mass of C2AS and a C3A content of 20 parts by mass or less per 100 parts by mass of C2S, a powdered cement composition containing Portland cement, (B) water, and (C) aggregate. According to this cementitious hardened body, carbon dioxide emissions can be significantly reduced by absorbing a large amount of carbon dioxide during the curing process, and although it contains powdered materials other than Portland cement, the rate of decrease in compressive strength can be reduced compared to the case where the entire amount of powdered material consists of Portland cement. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2021 / 193668 [Patent Document 2] Japanese Patent Publication No. 2020-157230 [Patent Document 3] Japanese Patent Publication No. 2011-168436 [Patent Document 4] Japanese Patent Publication No. 2016-047788 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a calcined product that can effectively utilize waste such as biomass ash, a hydraulic composition using the calcined product, and a carbonated hardened product obtained by carbonizing the hardened product of the hydraulic composition described above, which can significantly reduce the total amount of carbon dioxide emitted by absorbing a large amount of carbon dioxide during the curing process, and which has strength (e.g., compressive strength of mortar) equivalent to or less reduced than that of a conventionally manufactured cement hardened product (e.g., a hardened product using only ordinary Portland cement). [Means for solving the problem]

[0007] The inventors have diligently studied to solve the above problems and have found a solution containing belite and lanquinite, wherein the amount of lanquinite is 25 to 500 parts by mass per 100 parts by mass of belite, and 2CaO·(Al2O3) x (Fe2O3) 1-x We have discovered that the above objective can be achieved by a calcined product that does not contain the mineral represented by SiO2 (where X is a number between 0 and 1), or that contains the mineral and has an amount of the mineral of 60 parts by mass or less per 100 parts by mass of the total amount of belite and lanquinite, and have completed the present invention. In other words, the present invention provides the following [1] to

[10] . [1] A fired product containing belite and rankinite, wherein the amount of rankinite relative to 100 parts by mass of the belite is 25 to 500 parts by mass, and does not contain the mineral represented by the following chemical formula (1), or contains the mineral and the amount of the mineral relative to 100 parts by mass of the total amount of the belite and the rankinite is 60 parts by mass or less. 2CaO·(Al2O3) x ·(Fe2O3) 1-x ·SiO2···(1) (In the above chemical formula (1), X is a number from 0 to 1.) [2] The fired product according to [1] above, having a silica modulus (S.M.) of 3.0 to 20.0. [3] The fired product according to [1] or [2] above, wherein the proportion of alkali metal (R) is 1.0 to 4.0% by mass in terms of oxide (R2O). [4] The fired product according to any one of [1] to [3] above, wherein the proportion of free silicon dioxide is 1.0% by mass or less.

[0008] [5] A hydraulic composition containing an aggregate, cement, and water, comprising the fired product according to any one of [1] to [4] above. [6] A hydraulic composition containing a pulverized product of the fired product according to any one of [1] to [4] above, an aggregate, and water. [7] A carbonated cured body obtained by carbonating the cured body of the hydraulic composition according to [5] or [6] above. [8] A method for producing the fired product according to any one of [1] to [4] above, comprising a heating step of heating a raw material for firing containing a CaO source and a SiO2 source at 1,200 to 1,450 °C to obtain a fired product, wherein the molar ratio (CaO / SiO2) of CaO to SiO2 in the raw material for firing is 1.20 to 1.70. [9] The method for producing a fired product according to [8] above, wherein the silica modulus (S.M.) of the raw material for firing is 3.0 to 20.0.

[10] The method for producing a fired product according to [8] or [9] above, wherein the SiO2 source is biomass ash. [Effects of the Invention]

[0009] According to the fired product of the present invention and the hydraulic composition using the fired product, waste such as biomass ash can be effectively utilized. In addition, the carbonated cured body obtained by carbonating the cured body of the hydraulic composition can absorb a large amount of carbon dioxide during the curing process, and can significantly reduce the total amount of carbon dioxide emitted. Further, the carbonated cured body has the same strength (for example, the compressive strength of mortar) or a smaller reduction ratio compared to a cement cured body produced normally (for example, a cured body using only ordinary Portland cement).

Mode for Carrying Out the Invention

[0010] The fired product of the present invention contains belite (2CaO·SiO2: hereinafter may be abbreviated as "C2S") and rankinite (3CaO·2SiO2: hereinafter may be abbreviated as "C3S2"), and the amount of rankinite relative to 100 parts by mass of belite is 25 to 500 parts by mass, and does not contain the mineral represented by the following chemical formula (1), or contains the above mineral and the amount of the above mineral relative to 100 parts by mass of the total amount of belite and rankinite is 60 parts by mass or less. 2CaO·(Al2O3) x ·(Fe2O3) 1-x ·SiO2···(1) (In the above chemical formula (1), X is a number from 0 to 1.)

[0011] Examples of the mineral represented by the above chemical formula (1) include merlite and the like having one or more selected from the okermanite component (Ca2MgSi2O7), ferro-okermanite component (Ca2FeSi2O7), garenite component (Ca2Al2SiO7), sodamerlite component (CaNaAlSi2O7), hardystonite component (Ca2ZnSi2O7), gugiaite component (Ca2BeSi2O7), okayamaite component (Ca2B2SiO7), ferriegarenite component (Ca2Fe 3+ 2SiO7), and ferrialuminum garenite component (Ca2Fe 3+ AlSiO7) as the main end components.

[0012] The amount of lanquinite per 100 parts by mass of belite in the calcined product is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, from the viewpoint of obtaining a calcined product (aggregate) that is easy to calcin and has high strength, even at relatively low temperatures, the amount of lanquinite per 100 parts by mass of belite is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, even more preferably 50 parts by mass or more, and especially preferably 60 parts by mass or more. Furthermore, if the above amount is less than 25 parts by mass, the amount of carbon dioxide emissions during manufacturing will be high. Furthermore, when a carbonated hardened body (hereinafter also simply referred to as "carbonated hardened body") obtained by carbonizing a hardened hydraulic composition contains crushed calcined material, increasing the amount to 25 parts by mass or more increases the relative amount of lanquinite in the powdered hydraulic material (powdered material containing cement and crushed calcined material) contained in the hydraulic composition, thereby increasing the strength of the carbonated hardened body. In addition, the carbon dioxide absorption rate (amount of carbon dioxide absorbed per unit time) of the carbonated hardened body up to about 28 days of age can be increased. Furthermore, when a carbonated hardened body contains calcined material as aggregate, increasing the amount to 25 parts by mass or more increases the adhesion between the paste and aggregate interface due to carbonation of the aggregate surface, thereby increasing the strength of the carbonated hardened body.

[0013] The above amount is 500 parts by mass or less, preferably 250 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less, from the viewpoint of preventing a rapid increase in the amount of molten material generated at high temperatures during the production of the fired product, which would narrow the range of temperatures at which the fired product can be produced (firing temperature). Furthermore, when the hydraulic composition contains crushed calcined material, reducing the amount to 500 parts by mass or less increases the relative amount of belite in the powdered hydraulic material (powdered material containing cement and crushed calcined material) contained in the hydraulic composition, thereby improving the strength development of the hydraulic composition. In addition, the strength of the hardened body at the time of demolding during the manufacturing of the hardened body of the hydraulic composition can be increased. Furthermore, when the hydraulic composition contains calcined material as aggregate, reducing the amount to 500 parts by mass or less increases the adhesion between the paste and aggregate interface due to the hydration reaction on the aggregate surface, thereby improving the strength development of the hydraulic composition.

[0014] The amount of the mineral represented by the above chemical formula (1) (hereinafter sometimes abbreviated as "C2(A,F)S") per 100 parts by mass of the total amount of belite and lanquinite in the calcined product is 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. If the above amount exceeds 60 parts by mass, the amount of molten material increases rapidly at high temperatures when manufacturing the calcined product, so the range of temperatures (calcination temperature) in which the calcined product can be manufactured becomes narrower. Furthermore, when the hydraulic composition contains pulverized calcined material, reducing the amount to 60 parts by mass or less increases the relative amount of belite in the powdered hydraulic material (powdered material containing cement and pulverized calcined material) contained in the hydraulic composition, improving the strength development of the hydraulic composition. In addition, the strength of the hardened body at the time of demolding during the manufacturing of the hardened body of the hydraulic composition can be increased. Furthermore, when the hydraulic composition contains pulverized calcined material, reducing the amount to 60 parts by mass or less increases the carbon dioxide absorption rate of the carbonated hardened body obtained by carbonizing the hardened body of the hydraulic composition, improving the strength of the carbonated hardened body. Furthermore, when the hydraulic composition contains calcined material as aggregate, reducing the amount to 60 parts by mass or less increases the adhesion between the paste and aggregate interface due to hydration of the aggregate surface, thus improving the strength development of the hydraulic composition. Furthermore, the adhesion between the paste and aggregate interface increases due to carbonation of the aggregate surface, thus improving the strength of the carbonated hardened body.

[0015] The mineral composition of the calcined product (percentages of belite, lanquinite, and C2(A,F)S by mass %) can be calculated from the percentages of CaO, SiO2, Al2O3, Fe2O3, and P2O5 in the raw materials (calcination raw materials) or in the calcined product using the following formula. C2S=5.924×CaO-8.19×SiO2+0.483×Al2O3+0.308×Fe2O3-4.834×P2O5 C3S2=(-4.046×CaO)+7.547×SiO2-2.425×Al2O3-1.55×Fe2O3+4.782×P2O5 C2(A,F)S=(-0.879×CaO)+1.644×SiO2+2.943×Al2O3+2.241×Fe2O3+1.052×P2O5

[0016] The proportion of belite in the calcined product is preferably 20-80% by mass, more preferably 25-75% or more by mass, even more preferably 30-70% by mass, even more preferably 35-65% by mass, and particularly preferably 40-60% by mass, from the viewpoint of further improving the strength development of the hydraulic composition. Furthermore, if the above proportion is 20% by mass or more, the rapid generation of melt at high temperatures during the production of the calcined product is reduced, thus widening the range of temperatures (calcination temperatures) in which the calcined product can be produced. If the above amount is 80% by mass or less, the amount of free lime (amount of unreacted CaO) can be further reduced by raising the calcination temperature during calcination, making calcination easier. In addition, carbon dioxide emissions during production can be further reduced. The mineral form of belite in the fired product is not particularly limited and may be in any of the α, β, and γ forms. However, in the demolding process described later, it is preferable to include at least one of the α and β forms from the viewpoint of increasing the strength of the hardened body during demolding or enabling earlier demolding. Furthermore, the proportion of α and β belite in the total belite in the fired product is preferably 80% by mass or more. The morphology of minerals can be measured using methods such as powder X-ray diffraction and electron backscatter diffraction (EBSD).

[0017] The proportion of lanquinite in the calcined product is preferably 10-80% by mass, more preferably 15-70% by mass, even more preferably 20-60% by mass, and particularly preferably 25-50% by mass. If the above proportion is 10% by mass or more, the amount of free lime (amount of unreacted CaO) can be reduced more easily by increasing the calcination temperature during calcination, making calcination easier. In addition, carbon dioxide emissions during manufacturing can be reduced. Furthermore, when the hydraulic composition contains crushed calcined material, increasing the above ratio to 10% by mass or more relatively increases the amount of lankinite in the powdered hydraulic material (powdered material containing cement and crushed calcined material) contained in the hydraulic composition, resulting in greater strength of the carbonated hardened body obtained by carbonizing the hardened body of the hydraulic composition. Also, when the hydraulic composition contains calcined material as aggregate, increasing the above ratio to 10% by mass or more increases the adhesion between the paste and aggregate interface due to carbonation of the aggregate surface, resulting in greater strength of the carbonated hardened body. If the above proportion is 80% by mass or less, the rapid generation of molten material at high temperatures during the production of the fired product will be reduced, thus widening the range of temperatures (firing temperatures) in which the fired product can be produced. Furthermore, when the hydraulic composition contains crushed calcined material, by setting the above ratio to 80% by mass or less, the amount of belite in the powdered hydraulic material (powdered material containing cement and crushed calcined material) contained in the hydraulic composition becomes relatively larger, improving the strength development of the hydraulic composition. In addition, the strength of the hardened body at the time of demolding during the manufacturing of the hardened body of the hydraulic composition can be made greater. Furthermore, when the hydraulic composition contains calcined material as aggregate, the adhesion force between the paste and aggregate interface increases due to hydration of the aggregate surface, thus improving the strength development of the hydraulic composition.

[0018] The proportion of C2(A,F)S in the fired product is preferably 35% by mass or less, more preferably 25% by mass or less, and particularly preferably 20% by mass or less. When the above proportion is 35% by mass or less, the rapid generation of melt at high temperatures during the production of the fired product is reduced, thus widening the range of temperatures (firing temperature) in which the fired product can be produced. In addition, the strength development of the hydraulic composition containing the fired product is further improved. The amount of carbon dioxide absorbed by the carbonated hardened body obtained by carbonizing the hardened body of the above hydraulic composition is increased. Furthermore, the strength of the carbonated hardened body can be increased up to about 28 days of age.

[0019] The silica content (SM) of the calcined product is preferably 3.0 to 20.0, more preferably 4.0 to 19.0, even more preferably 5.0 to 18.0, even more preferably 8.0 to 17.0, even more preferably 10.0 to 17.0, and particularly preferably 12.0 to 17.0, from the viewpoint of improving the strength development of the hydraulic composition containing the calcined product. Furthermore, if the silica content (SM) in the calcined product is outside the above numerical range, the mineral composition of belite, lanquinite, and C2(A,F)S in the calcined product may not satisfy the mineral composition of the calcined product of the present invention as described above. Moreover, if the silica content is 3.0 or higher, the calcined product can absorb a larger amount of carbon dioxide. In addition, the strength of the carbonated hardened body can be increased up to about 28 days of age.

[0020] The Al2O3 content in the calcined product is preferably 1.0 to 7.0% by mass, more preferably 1.2 to 6.0% by mass, even more preferably 1.5 to 4.0% by mass, and particularly preferably 1.5 to 3.0% by mass, from the viewpoint of improving the strength development of the hydraulic composition containing the calcined product. Furthermore, if the above content is outside the above numerical range, the mineral composition of belite, lankinite, and C2(A,F)S in the calcined product may not satisfy the mineral composition of the calcined product of the present invention as described above. Moreover, if the above content is 7.0% by mass or less, the amount of C2(A,F)S will be reduced, and the strength development of the hydraulic composition containing the calcined product can be further improved. In addition, the carbonated hardened body can absorb a larger amount of carbon dioxide. Furthermore, the strength of the carbonated hardened body can be increased up to about 28 days of age.

[0021] The proportion of alkali metal (R) in the calcined product is preferably 1.0 to 4.0% by mass, more preferably 1.1 to 3.0% by mass, and particularly preferably 1.2 to 2.5% by mass, in terms of oxide (R2O). If the above proportion is 1.0% by mass or more, the amount of γ-type belite contained in the calcined product decreases, and the strength development of the hydraulic composition containing the calcined product is further improved. In addition, the amount of calcined product that can be used as aggregate without becoming powdery increases. If the above proportion is 4.0% by mass or less, a large amount of alkali metal (R) is fixed as lanquinite or C2(A,F)S, so alkali-aggregate reaction in the hydraulic composition containing the calcined product becomes less likely to occur. Furthermore, when the hardened body of the hydraulic composition containing the calcined product is carbonated, even if lanquinite decomposes, there is no risk of alkali-aggregate reaction occurring because the pH of the hardened body is low. Alkali metals typically refer to sodium (Na) and potassium (K). Furthermore, the proportion of alkali metal (R) in terms of oxide (R2O) can be calculated from the respective proportions (mass%) of Na2O and K2O in the calcined product using the following formula (2). R2O = Na2O + 0.658K2O ... (2)

[0022] The proportion of free lime in the fired product is preferably 2.0% by mass or less, more preferably 0.1 - 1.5% by mass, and particularly preferably 0.2 - 1.0% by mass, from the viewpoints of preventing disintegration when used as an aggregate and improving the strength development of the hydraulic composition and carbonation hardened body described below. The proportion of free silicon dioxide in the fired product is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less, from the viewpoints of enabling the sintering reaction of the fired product to proceed sufficiently so that it can be used as an aggregate with high density and low water absorption, and improving the strength development in the carbonation curing step of the method for producing a carbonation hardened body described below, in which belite and rankinite are sufficiently produced.

[0023] In addition to the above-described minerals of belite, rankinite, and C2(A,F)S, the fired product may contain other minerals and compound phases. Examples of other minerals and compound phases include mullite, anorthite, amorphous phase, and wollastonite. These may be contained singly or in combination of two or more. The proportion of each of the above-described minerals and compound phases can be determined by microscopic observation (point counting method) or the Rietveld method by powder X-ray diffraction. Also, from the viewpoint of strength development of the hydraulic composition containing the fired product, etc., the total proportion of the inclusions other than the above-described belite, rankinite, and C2(A,F)S in the fired product is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0024] The absolute dry density of the fired product is preferably 2.8 g / cm 3 or more, more preferably 2.85 g / cm 3 or more, still more preferably 2.9 g / cm 3 or more. If the above absolute dry density is 2.8 g / cm 3 or more, the strength of the hydraulic composition containing the fired product after curing will be higher. The water absorption rate of the fired product is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. If the water absorption rate is 10% by mass or less, the strength of the hydraulic composition containing the fired product after hardening will be higher. Furthermore, the oven-dry density and water absorption rate of the fired material can be measured in accordance with "JIS A 1109:2020 (Test method for density and water absorption rate of fine aggregate)" or "JIS A 1110:2020 (Test method for density and water absorption rate of coarse aggregate)".

[0025] An example of a method for producing a calcined product according to the present invention is a method that includes a heating step of heating calcination raw materials containing a CaO source and an SiO2 source at 1,200 to 1,450°C to obtain a calcined product, wherein the molar ratio of CaO to SiO2 in the calcination raw materials (CaO / SiO2) is 1.20 to 1.70. CaO sources for calcination include calcium-containing materials such as limestone, quicklime, slaked lime, seashells, and industrial waste. These may be used individually or in combination of two or more. Sources of SiO2 include industrial waste, general waste, and construction-generated soil. Using industrial waste as an SiO2 source can promote the effective utilization of waste.

[0026] Here, industrial waste refers to waste generated as a result of business activities (excluding "construction-generated soil" as described later). Examples of industrial waste include ready-mix concrete sludge, various types of sludge (e.g., sewage sludge, water treatment sludge, steelmaking sludge, etc.), construction waste, concrete waste, various types of incineration ash (e.g., biomass ash, coal ash, chicken manure ash, livestock manure ash, sludge incineration ash), foundry sand, rock wool, waste glass, blast furnace secondary ash, various by-products, and unused resources (materials remaining without being used, etc.). General waste refers to waste other than industrial waste (excluding "construction-generated soil" as described later). Examples of general waste include dry sewage sludge powder and municipal solid waste incineration ash. Examples of construction-generated soil include soil and sediment generated incidentally at construction sites and other work sites (for example, boring waste soil generated from ground excavation), surplus soil, waste soil, and construction sludge (for example, a mixture of cement grout and excavated soil generated during ground improvement work). These may be used individually or in combination of two or more types. Furthermore, silicon-containing raw materials such as silica and clay, which are common raw materials used in the manufacture of cement clinker, may be used as SiO2 sources. Volcanic materials such as volcanic ash may also be used as SiO2 sources. Furthermore, the firing raw materials may include common raw materials used in the production of cement clinker, such as aluminum-containing raw materials (Al2O3 source) like clay, and iron-containing raw materials (Fe2O3 source) like iron slag and iron cake, to the extent that they do not hinder the effects of the present invention.

[0027] The hydraulic modulus (HM) of the calcining raw materials is preferably 1.20 to 1.70, more preferably 1.30 to 1.65, even more preferably 1.35 to 1.60, and particularly preferably 1.40 to 1.50. If the hydraulic modulus is outside the above numerical range, the mineral composition of the calcined product obtained by calcining the calcining raw materials (the proportions of belite, lanquinite, and C2(A,F)S: mass%) may not satisfy the mineral composition of the calcined product of the present invention. Furthermore, the molar ratio of CaO to SiO2 in the calcination raw materials (CaO / SiO2) is 1.20 to 1.70, preferably 1.30 to 1.65, more preferably 1.40 to 1.60, and particularly preferably 1.45 to 1.58. If the molar ratio is outside the above numerical range, the mineral composition of the calcined product obtained by calcining the calcination raw materials (the proportions of belite, lanquinite, and C2(A,F)S: mass%) may not satisfy the mineral composition of the calcined product of the present invention.

[0028] The silica content (SM) of the calcination raw material is preferably 3.0 to 20.0, more preferably 4.0 to 19.0, even more preferably 5.0 to 18.0, even more preferably 8.0 to 17.0, even more preferably 10.0 to 17.0, and particularly preferably 12.0 to 17.0. If the silica content is within the above numerical range, a calcined product satisfying the mineral composition of the calcined product of the present invention (percentages of belite, lanquinite, and C2(A,F)S: mass%) can be easily obtained. Furthermore, if the silica content is 3.0 or higher, the amount of biomass ash used as the calcination raw material can be increased. If the silica content is 20.0 or lower, the total amount of waste contained in the calcination raw material can be increased.

[0029] In order to keep the silica content (SM) of the raw materials for calcination within the above numerical range, and from the viewpoint of effectively utilizing waste, it is preferable to use at least one of biomass ash and construction-generated soil as the SiO2 source for the raw materials for calcination. Here, biomass refers to "organic resources derived from plants and animals (excluding fossil resources)." Biomass ash refers to calcined ash produced by burning biomass. Examples of biomass ash include incinerated ash from plants and bamboo, and incinerated ash from food waste. Biomass ash may also be incinerated ash obtained by mixing and burning biomass and coal. From the viewpoint of promoting the effective utilization of biomass, the proportion of biomass-derived ash in the incinerated ash is preferably 50% by mass or more.

[0030] Examples of methods for calcining (incinerating, burning) biomass ash include methods using stoker-type combustion furnaces and methods using fluidized bed combustion furnaces. When a fluidized bed combustion furnace is used, limestone is added in the furnace for the purpose of desulfurization, so the resulting biomass ash contains calcium and sulfur. The calcium can also be used as a source of CaO for calcination raw materials, which does not generate carbon dioxide during calcination. In this case, the proportion of CaO in the biomass ash is preferably 10% to 40% by mass, more preferably 15% to 30% by mass. The sulfur is contained as gypsum in the calcined product. In particular, fly ash from a fluidized bed combustion furnace is preferred as biomass ash because it has a fine particle size, is easy to crush and mix, and has high calcination properties. Examples of fluidized bed combustion furnaces include circulating fluidized bed combustion furnaces and pressurized fluidized bed combustion furnaces.

[0031] The median diameter (D50) of biomass ash obtained by a fluidized bed combustion furnace is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 90 μm or less. The above median diameter can be measured using a laser diffraction / scattering particle size distribution analyzer. Specifically, it can be measured using a particle size distribution analyzer (MW3300EXII) manufactured by Microtrac-Bell, after ultrasonic dispersion for 1 minute with ethanol as the dispersion medium. Note that the median diameter (D50) refers to the particle size at a cumulative 50% in the volume-based particle size distribution.

[0032] In the method using a fluidized bed combustion furnace, sand mainly composed of quartz is introduced as the fluidizing medium. As a result, the resulting biomass ash contains melted and solidified or aggregated glass or sand-derived particles (relatively coarse particles), and the aforementioned limestone-derived or biomass-derived particles containing alkali metals and chlorine (relatively fine particles). Therefore, by classifying and collecting the coarse particles of biomass ash using an arbitrarily selected particle size as the classification point, which lies between the peaks for smaller and larger particle sizes in the particle size distribution of biomass ash, chlorine can be efficiently removed from the biomass ash. Furthermore, since the coarse-grained portion of biomass ash has a lower Al2O3 content than the fine-grained portion, using the classified coarse-grained portion can increase the silica content (SM) of the raw material for calcination and the calcined product. The above classification point can be arbitrarily selected within the range of preferably 20 to 100 μm, more preferably 30 to 90 μm, and particularly preferably 38 to 75 μm, from the viewpoint of further removing chlorine.

[0033] The apparatus for classifying biomass ash is not particularly limited as long as it can classify the biomass ash at classification points on the order of μm as described above. Examples include sieves, gravity sedimentation, inertial classifiers, centrifugal classifiers, and gravity classifiers. Among these, cyclone-type air separators, vortex-type centrifugal classifiers, and sieving apparatuses are preferred from the viewpoint of classification accuracy. Furthermore, when classification is performed wet, chlorine dissolves in water, resulting in fine particles that contain almost no chlorine. In addition, fluidized bed incinerators may be equipped with boilers, air preheaters, and high-temperature gas flow paths, as well as equipment for recovering settled incinerated ash, such as cyclone-based ash recovery equipment and bag filter-based ash recovery equipment. The particle size of the incinerated ash recovered by these recovery facilities varies depending on the facility, and it is possible to recover biomass ash of a specific particle size from a specific recovery facility. Therefore, instead of a classification device, the above equipment can be used to recover biomass ash with a specific particle size distribution.

[0034] The proportion of Al2O3 in the calcination raw materials (based on ignition raw materials) is preferably 1.0 to 7.0% by mass, more preferably 1.5 to 5.0% by mass, and particularly preferably 2.0 to 3.0% by mass. If the above proportion is outside the above numerical range, the mineral composition of belite, lanquinite, and C2(A,F)S in the resulting calcined product may not satisfy the mineral composition of the calcined product of the present invention as described above. Furthermore, if the above proportion is 7.0% by mass or less, the amount of C2(A,F)S will be reduced, and the strength development of the hydraulic composition containing the calcined product can be further improved. In addition, the calcined product can absorb a larger amount of carbon dioxide. Furthermore, the proportion of Al2O3 in biomass ash and construction-generated soil is lower than that in typical coal ash. Therefore, even if a larger amount of at least one of biomass ash and construction-generated soil is used as a raw material for calcination, it is possible to obtain calcined products that satisfy the mineral composition of the present invention.

[0035] Furthermore, the proportion of alkali metal (R) in the calcination raw materials (based on ignition raw materials) is preferably 1.0 to 4.0% by mass, more preferably 1.1 to 3.0% by mass, and particularly preferably 1.2 to 2.5% by mass, in terms of oxide (R2O). If the above proportion is 1.0% by mass or more, the amount of γ-type belite contained in the resulting calcined product will be small, and the strength development of the hydraulic composition containing the calcined product will be further improved. In addition, the amount of calcined product that can be used as aggregate will be greater, as the calcined product will not become powdery. If the above proportion is 4.0% by mass or less, since a large amount of alkali metal (R) will be fixed as lanquinite or C2(A,F)S, alkali-aggregate reaction will be less likely to occur in the hydraulic composition containing the calcined product. Furthermore, the proportion of alkali metals (R) in biomass ash and construction waste soil is higher than that in typical coal ash. Thus, waste materials such as biomass ash, construction waste soil, glass, volcanic materials, and kiln dust, which have a high proportion of alkali metals (R), have traditionally been difficult to use as raw materials for cement. However, by using them as raw materials for the calcined products of the present invention, a larger amount of waste materials such as biomass ash with a high proportion of alkali metals (R) can be utilized. Furthermore, the proportion of chlorine (Cl) in biomass ash is at most about 1% by mass. The proportion of Cl in biomass ash is higher than the typical proportion of Cl in coal ash, but lower than the typical proportion of Cl in municipal solid waste incineration ash. Normally, Cl in biomass ash volatilizes when the raw materials for calcination are calcined, so the resulting calcined product contains almost no Cl. However, Cl in biomass ash can be removed beforehand by washing or the classification process described above, thereby reducing the load on the calcination process.

[0036] The composition of the calcination raw materials should be adjusted as needed by appropriately adjusting the CaO source, SiO2 source, etc., so that the calcination raw materials satisfy the above-mentioned values ​​for water hardness, etc., and the mineral composition of the calcined product (the proportions of belite, lanquinite, and C2(A,F)S: mass%) obtained by calcining the raw materials reaches the desired value. Furthermore, the CaO source, SiO2 source, etc., may be mixed and crushed as appropriate. The method for mixing the various raw materials (CaO source, SiO2 source) contained in the calcination raw materials is not particularly limited, and methods using conventional equipment are among the options.

[0037] The above-mentioned fired product can be obtained by firing the firing material at a firing temperature preferably of 1,000 to 1,450°C, more preferably of 1,150 to 1,400°C. Compared to Portland cement, the calcined product of the present invention requires less limestone as a raw material and can be manufactured at a lower calcination temperature. Therefore, by using it as a raw material for the hydraulic composition described later, carbon dioxide emissions can be further reduced. Furthermore, the equipment used for firing is not particularly limited; for example, a rotary kiln can be used. When firing using a rotary kiln, waste materials such as waste oil, waste tires, and waste plastics may be used as fuel substitutes.

[0038] The fired product of the present invention can be used as is, or after adjusting the particle size by crushing, etc., as a civil engineering material such as roadbed material or backfill material. Furthermore, the calcined product of the present invention may be used as a material for a hydraulic composition. For example, after adjusting the particle size of the fired product, it can be used as aggregate for mortar or concrete. Furthermore, the fired product has a Blaine specific surface area of ​​preferably 2,500 to 10,000 cm². 2 / g, more preferably 3,000 to 9,000 cm 2 The material is ground down to a weight of / g, and the resulting pulverized material can be used as a filler, cement mixture, and cement admixture. Existing gypsum or grinding aids may be added during grinding. When the above pulverized material is used as a cement mixture or cement admixture, effects such as reduced bleeding, improved fluidity, and reduced heat of hydration can be obtained in the hydraulic composition containing the above pulverized material. When the above-mentioned crushed material is used as a cement admixture, mixing 5 to 25 parts by mass of the above-mentioned crushed material with 100 parts by mass of rapid-hardening Portland cement, rapid-hardening Portland cement clinker, high-C3A content cement (specifically 10 to 15% by mass), or high-C3A content cement clinker will produce cement of equivalent quality to ordinary Portland cement.

[0039] Examples of hydraulic compositions containing the above-mentioned calcined material include: (1) hydraulic composition A containing cement, water, and aggregate made of the above-mentioned calcined material; (2) hydraulic composition B containing pulverized material of the above-mentioned calcined material, aggregate, and water; and (3) hydraulic composition C containing pulverized material of the above-mentioned calcined material, aggregate made of the above-mentioned calcined material, and water. The hardened body of the above hydraulic composition may be used in various applications such as mortar or concrete without carbonation, or it may be used in various applications as a hardened body obtained by carbonation of the above hydraulic composition. In the following, when producing a carbonated hardened body obtained by carbonizing the hardened bodies of hydraulic compositions A to C, which include the calcined products described above, each material contained in the hydraulic compositions will be explained in detail. In this specification, a hydraulic composition refers to a curable composition containing a powdered hydraulic material and water, encompassing both the pre-curing and post-curing forms of the hydraulic composition. Examples of hydraulic compositions include pastes, mortars, and concretes. Furthermore, in this specification, "powdered hydraulic material" refers to inorganic powders other than aggregate and water contained in the hydraulic composition (cement, cement admixtures, crushed calcined products as described above, etc.).

[0040] [Powdered material consisting of the calcined material described above] The hydraulic composition may also contain pulverized material obtained by crushing the above-mentioned calcined material (hereinafter also referred to as "calcined material pulverized material"), from the viewpoint of promoting the effective utilization of waste such as biomass ash and the carbonated hardened body obtained by carbonizing the hardened body of the hydraulic composition, which absorbs more carbon dioxide and further reduces the total amount of carbon dioxide emitted. The Blaine specific surface area of ​​the calcined and pulverized material is preferably 2,500 to 10,000 cm². 2 / g, more preferably 3,000 to 9,000 cm 2 The value is / g. The above Brain specific surface area is 2,500 cm². 2 If the concentration is above / g, the effect of reducing carbon dioxide emissions will be greater. In addition, the strength of the resulting carbonated hardened material will be greater. The above Blaine specific surface area is 10,000 cm². 2 If the amount is less than / g, the energy required for grinding can be kept lower, thus reducing manufacturing costs. The method for crushing the calcined material described above is not particularly limited, and can include using conventional equipment such as a ball mill.

[0041] When the hydraulic composition contains pulverized calcined material, the proportion of pulverized calcined material in the powdered hydraulic material (inorganic powder other than water and aggregate contained in the hydraulic composition) is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of further increasing the effect of reducing carbon dioxide emissions and further increasing the strength of the carbonated hardened body. Furthermore, from the viewpoint of increasing the strength of the cured body when demolding, or shortening the timing of demolding, and thereby improving the production efficiency of products made of carbonated cured bodies, the above ratio is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less. When a hydraulic composition contains crushed calcined material but does not contain cement (for example, when the above ratio is 100% by mass), the Blaine specific surface area of ​​the crushed calcined material should be increased (for example, 8,000 to 12,000 cm²) from the viewpoint of strength development of the hydraulic composition. 2 It is preferable to perform at least one of the following: (to make it / g) and heat curing.

[0042] [cement] From the viewpoint of improving strength development, the hydraulic composition preferably contains cement. The cement included in the hydraulic composition is not particularly limited and includes, for example, various types of Portland cement such as ordinary Portland cement, rapid-hardening Portland cement, moderate-heat Portland cement, and low-heat Portland cement, as well as eco-cement, fast-setting cement, and ultra-fast-setting cement. These may be used individually or in combination of two or more types. In particular, from the viewpoint of strength development and cost, at least one of ordinary Portland cement and rapid-hardening Portland cement is preferred.

[0043] When the hydraulic composition contains cement, the proportion of cement in the powdered hydraulic material can be relatively increased to increase the proportion of crushed calcined material. From the viewpoint of obtaining the effects of increasing the proportion of crushed calcined material (effect of reducing carbon dioxide emissions and effect of increasing the strength of the carbonated hardened body), the proportion is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 40% by mass or less. Furthermore, from the viewpoint of increasing the strength of the cured body when demolding, or shortening the timing of demolding, and thereby improving the production efficiency of products made of carbonated cured bodies, the amount is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 60% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0044] [Gypsum powder] The hydraulic composition may contain gypsum powder from the viewpoint of fluidity and workability before hardening. The gypsum used is not particularly limited and includes, for example, natural dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric acid gypsum, etc. Examples of gypsum forms include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. These may be used individually or in combination of two or more types. The proportion of gypsum powder in the powdered hydraulic material is preferably 5.0% by mass or less, and more preferably 1.0 to 4.0% by mass, in terms of SO3. If the above proportion is 5.0% by mass or less, the fluidity of the hydraulic composition before hardening is further improved. Furthermore, if the hydraulic composition contains cement, the above proportion of gypsum powder shall include the gypsum powder contained in the cement. Gypsum may be used as gypsum powder, which has been pre-ground, or it may be used as a mixture of ground calcined material and gypsum powder, which is obtained by simultaneously grinding the calcined material and gypsum during the production of the calcined material powder.

[0045] [Amines] The hydraulic composition may contain amines. Amines are known to react with carbon dioxide to promote the formation of carbonate ions, and when the hydraulic composition contains amines, the carbonation of the calcium component contained in the hydraulic composition can be efficiently promoted. Amines are substances that contain both an amino group and a hydroxyl group in their molecule. Examples of amines include monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diglycolamine (DGA), diisopropanolamine (DIPA), methyldiethanolamine (MDEA), and triisopropanolamine (TIPA). These amines are generally known as grinding aids. Furthermore, as amines, used amines recovered from amine-based carbon dioxide recovery equipment used to recover carbon dioxide from exhaust gases of factories and the like may also be used. The liquid containing the above-mentioned used amines is usually discarded, but in the present invention, the above-mentioned waste liquid can be effectively utilized. The amines may also be used as grinding aids. The amount of amines is preferably 0.002 to 1 part by mass, more preferably 0.01 to 0.1 parts by mass, per 100 parts by mass of powdered hydraulic material, from the viewpoint of accelerating the carbonation of the hardened body and improving the strength development in the carbonation curing process.

[0046] The proportion of free lime in the powdered hydraulic material is preferably 2.0% by mass or less, and more preferably 0.2 to 1.5% by mass, from the viewpoint of strength development in the carbonation curing process (described later).

[0047] [water] The water used in this invention is not particularly limited and includes tap water, sludge water, and the like. In the hydraulic composition, the mass ratio of water to powdered hydraulic material (water / powdered hydraulic material) is preferably 0.3 to 1.0, more preferably 0.4 to 0.7. If the above ratio is 0.3 or higher, the effect of reducing carbon dioxide emissions will be greater. In addition, the workability of the kneaded hydraulic composition will be improved. If the above ratio is 1.0 or lower, the strength of the carbonated hardened product will be greater.

[0048] [Aggregate made from the above-mentioned fired material] The hydraulic composition may contain aggregate made from the aforementioned calcined material (hereinafter also referred to as "calcined aggregate"), from the viewpoint of promoting the effective utilization of waste such as biomass ash and reducing the total amount of carbon dioxide emitted by the carbonated hardened body. In this case, the calcined aggregate may be included in the hydraulic composition as at least one of the fine aggregate and coarse aggregate. Furthermore, the calcined aggregate can be obtained by appropriately crushing or adjusting the particle size of the calcined material described above so that it has a particle size suitable for use as the desired aggregate. The surface of the calcined aggregate is mostly composed of C2S and C3S2, and their carbonation increases the total amount of carbon dioxide absorbed by the carbonated hardened material, thereby increasing the strength of the carbonated hardened material.

[0049] The calcined aggregate included in the hydraulic composition may be included as fine aggregate if the hydraulic composition is mortar, or as at least one of fine aggregate and coarse aggregate if the hydraulic composition is concrete. However, it is preferable that it be included as fine aggregate from the viewpoint of increasing the total amount of carbon dioxide absorbed by the carbonated hardened body. The proportion of calcined aggregate in the total amount of aggregate contained in the hydraulic composition is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. If the above proportion is 20% by mass or more, the total amount of carbon dioxide that the carbonated hardened body can absorb can be increased compared to when general aggregate is used, and the strength of the carbonated hardened body can be increased.

[0050] Furthermore, when the calcined aggregate is fine aggregate, the proportion of calcined aggregate in the total amount of fine aggregate is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. If the above proportion is 20% by mass or more, the total amount of carbon dioxide that the carbonated hardened body can absorb can be increased compared to when general aggregate is used, and the strength of the carbonated hardened body can be increased. When only calcined aggregate is used as the aggregate in the hydraulic composition, the carbonated hardened body (carbonated hardened body) obtained by carbonizing the hardened body of the hydraulic composition of the present invention can be used, and after using the carbonated hardened body, the entire amount can be recovered and reused as a raw material for the calcined product or as a raw material for cement clinker of the present invention. In this case, cement clinker can be manufactured by adding only a small amount of new raw material.

[0051] The hydraulic composition may contain aggregates other than calcined aggregates. Examples of fine aggregates other than calcined aggregates include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, slag, lightweight fine aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof. Examples of coarse aggregates other than calcined aggregates include river gravel, mountain gravel, land gravel, crushed stone, slag, lightweight coarse aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof.

[0052] From the viewpoint of reducing shrinkage during carbonation curing and service life, and further improving dimensional stability, it is preferable that the material of aggregates other than the calcined aggregates be limestone or dolomite (specifically, crushed limestone sand, crushed limestone, crushed dolomite sand, crushed dolomite, and recycled aggregates thereof). Furthermore, if the material of aggregates other than the calcined aggregates is limestone or dolomite, the carbonized hardened body can be recovered after use and entirely utilized as a raw material for cement clinker. In this case, cement clinker can be manufactured by adding only a small amount of new raw material.

[0053] Furthermore, it is preferable that aggregates other than calcined aggregates are recycled aggregates obtained from waste concrete, or aggregates obtained from crushed demolition concrete or demolition mortar, or solidified concrete sludge. The surface of these aggregates is coated with cement clinker minerals or their hydrates, and the carbonation of the cement clinker minerals or their hydrates from the coated portion can increase the total amount of carbon dioxide absorbed into the carbonated hardened body, and can also increase the strength of the carbonated hardened body obtained after carbonation curing.

[0054] When the hydraulic composition contains coarse aggregate, the fine aggregate ratio is preferably 5-60%. If the fine aggregate ratio is within this range, the workability and ease of molding of the mixture are improved. The amount of aggregate (the total amount if fine aggregate and coarse aggregate are used in combination) is preferably 200 to 700 parts by mass, more preferably 200 to 600 parts by mass, per 100 parts by mass of powdered hydraulic material. If the blending amount is within the above range, the strength of the carbonated hardened body will be increased and the shrinkage rate of the carbonated hardened body will be reduced. The coarseness ratio when fine aggregate and coarse aggregate are combined is preferably 1.0 to 7.0, more preferably 1.5 to 6.5.

[0055] [Other materials] The hydraulic composition may contain other materials as needed, provided that they do not hinder the objectives of the present invention. Other materials that may be added as needed include various additives such as water-reducing agents, defoaming agents, and shrinkage-reducing agents, as well as various admixtures such as fly ash, silica fume, blast furnace slag powder, and limestone powder. Furthermore, hardening agents and curing accelerators may be added to increase initial strength and improve handling. The proportion of other materials in the hydraulic composition varies depending on the type of other material, but is, for example, 20% by mass or less, preferably 10% by mass or less.

[0056] A carbonated hardened body can be produced by carbonizing a hardened body of a hydraulic composition containing the above-mentioned calcined material (for example, hydraulic compositions A to C). Here, "carbonation" refers to the reaction of alkaline components in the hardened body of a hydraulic composition with carbon dioxide, which lowers the pH of the alkaline components. The following is an example of a method for manufacturing a carbonated hardened body, which includes a mixture preparation step of mixing (A) powdered hydraulic material, (B) water, and (C) aggregate to prepare a mixture of hydraulic composition; a casting step of casting the mixture into a mold; a demolding step of demolding the hardened hydraulic composition from the mold after the mixture in the mold has hardened; and a carbonation curing step of carbonizing the hardened hydraulic composition that has been demolded from the mold to obtain a carbonated hardened body. The following explains each step in detail.

[0057] [Preparation process for kneaded products] This process involves kneading the aforementioned (A) powdered hydraulic material, (B) water, and (C) aggregate to prepare a kneaded hydraulic composition. The method of mixing each ingredient is not particularly limited. Furthermore, the equipment used for mixing is also not particularly limited; for example, conventional mixers such as omni mixers, pan mixers, twin-shaft mixers, and tilting-drum mixers can be used. In addition, components (A) to (C) above may be kneaded with amines during this process. [Concrete pouring process] This process involves pouring the mixture obtained in the previous process into a mold. The concrete placement method is not particularly limited, and conventional methods such as pour molding can be used. The curing method after pouring the mixed material into the formwork until demolding is not particularly limited and can be any common method such as air curing, humid air curing, underwater curing, or steam curing. It is possible to adopt this. [Demolding process] This process involves demolding the hardened hydraulic composition, which is formed from the hardened mixture inside the mold, from the mold after the mixture has hardened.

[0058] [High strength curing process] This process is an optional step that can be set between the demolding process and the carbonation curing process, and is a process for increasing the strength of the hardened body of the hydraulic composition. In this process, the hardened body of the hydraulic composition demolded from the mold has a compressive strength of preferably 3 N / mm². 2 More preferably 5 N / mm 2 The above is particularly preferably 10 N / mm 2 By allowing the material to cure to this extent, the strength of the carbonated cured material after carbonation curing (for example, the compressive strength of mortar or concrete) can be increased. The curing method is not particularly limited; for example, general curing methods such as air curing, humid air curing, underwater curing, and steam curing can be used. However, "curing" in the high-strength curing process does not include carbonation curing.

[0059] [Carbonation curing process] This process involves carbonizing the hardened hydraulic composition that has been demolded from the mold, in order to obtain a carbonated hardened body obtained by carbonizing the hardened hydraulic composition. In this process, the concentration of carbon dioxide gas used for carbonation curing is preferably 1% by volume or more, more preferably 3% by volume or more, even more preferably 10% by volume or more, even more preferably 50% by volume or more, and particularly preferably 60% by volume or more. If the above concentration is 1% by volume or more, the amount of carbon dioxide absorbed in the carbonation curing process can be increased. The upper limit of the carbon dioxide gas concentration is not particularly limited; a higher concentration of carbon dioxide gas can increase the amount of carbon dioxide absorbed. However, from the viewpoint of reducing the cost of curing equipment, etc., it is preferably 90% by volume or less, more preferably 70% by volume or less, and particularly preferably 50% by volume or less.

[0060] Furthermore, the temperature in the carbonation curing process is not particularly limited, but is preferably 5 to 100°C, more preferably 10 to 50°C, and most preferably 15 to 35°C. If the temperature during carbonation curing is within the above numerical range, the productivity of products made from carbonic acid cured materials will be improved, and the strength of the carbonic acid cured materials can be increased. Furthermore, the carbonicated cured product of the present invention exhibits a significant reduction in carbon dioxide emissions even when carbonication curing is performed at relatively low temperatures (for example, 5 to 30°C). The relative humidity in this process is not particularly limited, but is preferably 20-90%, more preferably 30-80%, and most preferably 40-70%. If the relative humidity is 20% or higher, the productivity of the carbonated cured product will be further improved and the strength of the carbonated cured product will be greater. It is difficult to raise the relative humidity above 90%, and the costs associated with equipment, etc., will be excessive.

[0061] In the carbonation curing process, it is preferable to perform the carbonation curing so that the carbonation depth from the surface of the carbonized cured body is preferably 2 mm or more, more preferably 5 mm or more, even more preferably 8 mm or more, and particularly preferably 10 mm or more. By performing the carbonation curing so that the carbonation depth is 2 mm or more, a larger amount of carbon dioxide can be absorbed by the carbonized cured body. Specifically, the carbonation depth can be made 2 mm or more by appropriately adjusting the carbon dioxide gas concentration, temperature, relative humidity, and curing time in the carbonation curing process described above. Furthermore, from the viewpoint of absorbing carbon dioxide in a short time, it is preferable to perform carbonation curing at a material age of 1 day, more preferably at 3 days, so that the carbonation depth is 2 mm or more. Furthermore, the "carbonation depth from the surface of the carbonated hardened material" can be measured in accordance with "JIS A 1152:2018 (Method for measuring the carbonation depth of concrete)." The resulting carbonated hardened material can be used as roadbed material, interlocking blocks, etc. Furthermore, even after being installed as roadbed material, it can continue to absorb and fix carbon dioxide.

[0062] Furthermore, if the hydraulic composition contains calcined aggregate (aggregate made from the calcined material described above), a carbonation treatment may be performed on the calcined aggregate before the compound preparation step, from the viewpoint of improving the efficiency of carbonation. Furthermore, if excessive carbonation is performed on the calcined aggregate at this stage, one of the effects of the present invention, namely the improvement in the strength of the carbonated hardened body after carbonation curing, cannot be obtained.

[0063] The carbonated hardened body obtained by the above manufacturing method exhibits a reduction in the amount of carbon dioxide emitted during the production of the carbonated hardened body by preferably 15% or more (more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more) compared to cases where general Portland cement is used instead of the calcined aggregate (the calcined aggregate mentioned above), or where general aggregate is used instead of the calcined aggregate, and the rate of decrease in the strength (e.g., compressive strength) of the carbonated hardened body is preferably 50% or less (more preferably 40% or less).

[0064] In the production of hardened bodies of the hydraulic compositions (hydraulic compositions A to C) containing the calcined products described above, each material included in the hydraulic compositions will be explained in detail when carbonation is not performed. When the hydraulic composition contains pulverized calcined material, the proportion of pulverized calcined material in the powdered hydraulic material (inorganic powder other than water and aggregate contained in the hydraulic composition) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of further increasing the effect of reducing carbon dioxide emissions and further increasing the strength of the carbonated hardened body. Furthermore, from the viewpoint of increasing the strength of the cured body when demolding, or shortening the timing of demolding, and thereby improving the production efficiency of products made of carbonated cured bodies, the above ratio is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less, and particularly preferably 50% by mass or less.

[0065] When the hydraulic composition contains cement, the proportion of cement in the powdered hydraulic material can be relatively increased to increase the proportion of crushed calcined material. From the viewpoint of obtaining the effects of an increased proportion of crushed calcined material (effect of reducing carbon dioxide emissions and effect of increasing the strength of the carbonated hardened body), the proportion is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less. Furthermore, from the viewpoint of increasing the strength of the cured body when demolding, or shortening the demolding time, and thereby improving the production efficiency of products made of carbonated cured bodies, the amount is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more. The materials included in the above-mentioned hydraulic composition, other than the calcined pulverized material and cement, when carbonation is not performed, are the same as the materials included in the carbonated hardened body described above. [Examples]

[0066] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement; manufactured by Taiheiyo Cement Corporation, ordinary Portland cement, Blaine specific surface area: 3,240 cm² 2 / g, Gypsum (containing hemihydrate gypsum and dihydrate gypsum in a mass ratio of 62:38): 2.1% by mass in terms of SO3, Grinding aid (triethanolamine): 400 ppm (by mass), Free lime: 0.4% by mass (2) Fine aggregate A; Standard sand for cement strength testing, manufactured by the Cement Association. (3) Fine aggregate B; manufactured by Abegawa Kaihatsu Co., Ltd., mountain sand, absolute dry density: 2.54 g / cm³ 3 , water absorption rate: 2.1%, FM: 3.25, fine particle content: 5.4% by mass (4) Fine aggregate C: The calcined material A shown in Table 3 is crushed and the particle size is adjusted to have a particle size distribution equivalent to that of fine aggregate. Absolute dry density: 2.98 g / cm³ 3 , water absorption rate: 2.8%, FM: 3.21, fine particle content: 3.0% by mass (5) Water: Tap water (6) Biomass Ashes A-E: Table 1 shows the chemical composition of biomass ashes A-E measured by the calibration curve (coal ash) method using an X-ray fluorescence spectrometer (Rigaku Corporation, "ZSX Primus II"), the proportion of alkali metals (R) calculated from the chemical composition (converted to oxides (R2O): indicated as "R2O" in Table 1), and the silicic acid content (SM). Biomass ash C is the sieving residue obtained by classifying biomass ash B using a sieve with a mesh size of 45 μm (spin air sieve, Seishin Corporation, model number "SV-75 / 200"). Table 2 shows the particle size distribution of biomass ashes B and C measured using a laser diffraction particle size distribution analyzer (Microtrac-Bell Corporation, "MT3300EXII"). All biomass ashes were crushed until the 90 μm sieve residue was 15% by mass or less before use.

[0067] [Table 1]

[0068] [Table 2]

[0069] [Manufacturing of fired products A-E] The raw materials for calcination were prepared by mixing biomass ashes A to E, having the chemical compositions shown in Table 1, and calcium carbonate (reagent) in the mass ratios shown in Table 3. The molar ratio of CaO to SiO2 in the calcination raw materials (indicated as "Ca / Si molar ratio" in Table 3) is shown in Table 3. Water was added to the prepared calcination raw materials, granulated to 5-20 mm, dried, and calcined in a small rotary kiln at a calcination temperature of 1,300-1,375°C for a residence time of approximately 30 minutes to obtain calcined products A-E. Table 3 shows the silica content (SM), hydraulic content (HM), Al2O3 ratio, alkali metal ratio (in R2O equivalent), belite ratio, lanquinite ratio, amount of lanquinite per 100 parts by mass of belite, and the amount of C2(A,F)S relative to the total amount of belite and lanquinite for calcined products A-E. Furthermore, the amount of free lime in the obtained calcined products A to E was 0.5% by mass or less in all cases. In addition, the percentage of free silicon dioxide in the obtained calcined products A to E, measured in accordance with "JIS R 1616:2007 (Chemical analysis method for silicon carbide fine powder for fine ceramics)", was 0.2% by mass or less. Furthermore, when the mass ratio of calcium carbonate to the total amount of biomass ash and calcium carbonate in calcined product A (calcium carbonate ash / (biomass ash + calcium carbonate)) was set to 0.305 (Ca / Si molar ratio: 1.34, amount of lanquinite per 100 parts by mass of belite: 638 parts by mass, C2S content: 9.4% by mass), it rapidly melted at around 1,275°C, making calcination difficult, and the proportion of free silicon dioxide in the calcined product exceeded 1.0% by mass.

[0070] [Table 3]

[0071] [Examples 1-4, Comparative Example 1] The types of calcined materials shown in Table 4 and gypsum dihydrate were simultaneously pulverized to obtain a Blaine specific surface area of ​​5,000 ± 100 cm². 2 The result was a mixed powder in which the proportion of dihydrate gypsum in the mixed powder (a powder obtained by grinding the above-mentioned calcined product and dihydrate gypsum) was 2.0% by mass in terms of SO3. During grinding, triethanolamine was added as a grinding aid in an amount of 400 ppm per 100 parts by mass of the mixed powder. The obtained mixed powder and cement (ordinary Portland cement) were mixed according to the proportions shown in Table 4 to obtain a powdered hydraulic material. Mortar was prepared using a powdered hydraulic composition, fine aggregate A, and water, in accordance with "JIS R 5201:2015 (Physical Testing Methods for Cement)". The obtained mortar was filled into a 4 x 4 x 16 cm formwork, then cured in humid air at 20°C for 24 hours, followed by demolding. Subsequently, until 28 days of age, the mortar was cured by carbonation in an accelerated carbonation tank at 20°C and 60°C relative humidity. The carbon dioxide gas concentration during carbonation curing was 5% by volume.

[0072] The compressive strength of the mortar obtained from the test specimens was measured in accordance with "JIS R 5201:2015 (Physical Testing Methods for Cement)". In addition, the carbonation depth of the test specimens was measured in accordance with "JIS A 1152:2018 (Method for Measuring the Neutralization Depth of Concrete)".

[0073] [Reference example 1] Specimens were prepared in the same manner as in Example 1, except that ordinary Portland cement was used instead of powdered hydraulic material. The compressive strength of the mortar obtained was measured in the same manner as in Example 1.

[0074] [Example 5] Except for using ordinary Portland cement instead of powdered hydraulic material, using fine aggregate C (calcined material A with adjusted particle size) instead of fine aggregate A, and performing 28 days of underwater curing without carbonation curing, specimens were prepared in the same manner as in Example 1. The compressive strength of the mortar obtained was measured in the same manner as in Example 1. [Comparative Example 2] Except for using ordinary Portland cement instead of powdered hydraulic material, using fine aggregate B instead of fine aggregate A, and curing in water for 28 days without carbonation curing, the specimens were prepared in the same manner as in Example 1. The compressive strength of the mortar obtained was measured in the same manner as in Example 1. The results for each are shown in Table 4.

[0075] [Table 4]

[0076] Table 4 shows that when comparing Examples 1-4 with Comparative Example 1 and Reference Example 1, the carbonation depth (10-12 mm) of Examples 1-4 is greater than that of Comparative Example 1 and Reference Example 1 (4-7 mm), indicating that when the pulverized calcined product of the present invention is used as a powdered hydraulic material, the amount of carbon dioxide absorbed is greater. Furthermore, a comparison of the compressive strength of the mortars in Reference Example 1 and Examples 1-4, and a comparison of the compressive strength of the mortars in Reference Example 1 and Comparative Example 1, shows that when the pulverized calcined material of the present invention is used as a powdered hydraulic material, the degree of decrease in compressive strength is smaller than that of Comparative Example 1. In particular, the compressive strength of the mortars in Examples 1 and 3 is comparable to that of Reference Example 1. Furthermore, comparing Example 5 with Comparative Example 2, the compressive strength of the mortar in Example 5 was (62 N / mm²). 2 ) is the compressive strength (51 N / mm²) of the mortar in Comparative Example 2. 2 It is clear that the compressive strength of the mortar increases when aggregate made from the fired product of the present invention is used, as it is larger than the given material.

Claims

1. Contains beelite and lanquinite, The amount of the above-mentioned lankinite per 100 parts by mass of the above-mentioned belite is 25 to 100 parts by mass. A calcined product that does not contain the mineral represented by the following chemical formula (1), or contains the mineral represented by the following chemical formula (1) and the amount of the mineral represented by the following chemical formula (1) is 60 parts by mass or less per 100 parts by mass of the total amount of belite and lanquinite, In the above-mentioned fired product, the proportion of belite is 35 to 57.5% by mass, and the proportion of lanquinite is 20 to 50% by mass, and A hydraulic composition characterized by containing aggregate made from calcined material having a silica content (S.M.) of 8.0 to 19.0, cement, and water. 2CaO・(Al ２ O ３ )x・(Fe ２ O ３ ) １－ｘ ・SiO ２ ・・・(1) (In the above chemical formula (1), X is a number between 0 and 1.)

2. The proportion of alkali metals (R) in the above-mentioned calcined product is oxide (R) ２ The hydraulic composition according to claim 1, wherein the amount is 1.0 to 4.0% by mass in terms of O.

3. The hydraulic composition according to claim 1 or 2, wherein the proportion of free silicon dioxide in the above-mentioned calcined product is 1.0% by mass or less.

4. A carbonated hardened body obtained by carbonating a hardened body of a hydraulic composition according to any one of claims 1 to 3.

5. Contains beelite and lanquinite, The amount of the above-mentioned lankinite per 100 parts by mass of the above-mentioned belite is 25 to 100 parts by mass. A calcined product that does not contain the mineral represented by the following chemical formula (1), or contains the mineral represented by the following chemical formula (1) and the amount of the mineral represented by the following chemical formula (1) is 60 parts by mass or less per 100 parts by mass of the total amount of belite and lanquinite, In the above-mentioned fired product, the proportion of belite is 35 to 57.5% by mass, and the proportion of lanquinite is 20 to 50% by mass, and A method for producing a calcined product having a silica content (S.M.) of 8.0 to 19.0, CaO source and SiO ２ The process includes a heating step in which the raw materials for firing, including the source, are heated to 1,200 to 1,450°C to obtain a fired product. The manufacturing method of a fired product in which the molar ratio (CaO / SiO ２ ) of CaO and SiO of the raw material for firing is 1.20 to 1.

70. ２ ​ 2CaO・(Al 2 O 3 )x・(Fe 2 O 3 ) 1−x ・SiO 2 ...(1) (In the above chemical formula (1), X is a number between 0 and 1.)

6. The proportion of alkali metals (R) in the above-mentioned calcined product is oxide (R) ２ A method for producing a calcined product according to claim 5, wherein the amount is 1.0 to 4.0% by mass in terms of O.

7. The method for producing a calcined product according to claim 5 or 6, wherein the proportion of free silicon dioxide in the calcined product is 1.0% by mass or less.

8. A method for producing a fired product according to any one of claims 5 to 7, wherein the silica content (S.M.) of the above-mentioned firing raw material is 3.0 to 20.

0.

9. The above SiO ２ A method for producing a calcined product according to any one of claims 5 to 8, wherein the source is biomass ash.

Images