Method for manufacturing cementitious bodies

Abstract

To provide a method for producing a cementitious hardened body by which a larger amount of carbon dioxide is absorbed in a curing process, as a result, the total amount of discharged carbon dioxide can be reduced, and a cement composition having excellent strength developability can be obtained.SOLUTION: It is preferable that the hydraulic modulus (H. M.) is 1.1 to 2.0 (excluding 1.1 to 1.3). The silicate ratio (S. M.) is 1.5 to 3.5 (excluding 2.4 to 2.6). An iron ratio (I. M.) of 1.7 to 3.5 (excluding 2.0 to 2.3). A method for producing a hardened cementitious material, comprising a carbonation curing step of subjecting a cement composition to carbonation curing to obtain the hardened cementitious material, wherein the cement composition comprises gypsum, water, and a clinkers powder having a mineral composition in which the total content of aluminum oxides (Al2O3) and iron oxides (Fe2O3) is 9.0 to 14.0 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing a cementitious hardened body. [Background technology]

[0002] Currently, reducing carbon dioxide emissions is 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. Patent Document 1 describes a cementitious hardened body that can significantly reduce the total amount of carbon dioxide emitted by absorbing a large amount of carbon dioxide during the curing process, characterized in that the hardened body of a cement mixture containing (A) a powder for cement mixing containing either or both of mullite and anorthite, and a powdered cement composition containing Portland cement, (B) water, and (C) aggregate is carbonized. Furthermore, Patent Document 2 describes a cementitious hardened body characterized by carbonizing a hardened cement mixture containing (A) 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. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-153357 [Patent Document 2] Japanese Patent Publication No. 2016-47788 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide a method for producing a cementitious hardened body that can absorb more carbon dioxide during the curing process, thereby reducing the total amount of carbon dioxide emitted, and that can produce a cement composition with excellent strength development. [Means for solving the problem]

[0005] The inventors of this invention have conducted diligent studies to solve the above problems and have found that the water hardness modulus (HM) is 1.1 to 2.0 and , Silicate content (SM) is 1.5-3.5 and , iron content (IM) is 1.7~3.5 and Clinker powder having a mineral composition in which the total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) is 9.0 to 14.0% by mass. (However, the water hardness modulus (HM) is 1.1 to 1.3, the silicate modulus (SM) is 2.4 to 2.6, the iron modulus (IM) is 2.0 to 2.3, and aluminum oxide (Al 2 O 3 ) and iron oxide (Fe 2 O 3 (Excluding clinker powder having a mineral composition in which the total content of ) is 9.5 to 14.0% by mass.) We have found that the above objective can be achieved by a method for producing a cementitious hardened body, which includes a step of carbonizing and curing a cement composition containing gypsum and water to obtain a cementitious hardened body, and have completed the present invention. In other words, the present invention provides the following [1] to [3]. [1] Water hardness (HM) is 1.1-2.0 and , Silicate content (SM) is 1.5-3.5 and , iron content (IM) is 1.7~3.5 and Clinker powder having a mineral composition in which the total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) is 9.0 to 14.0% by mass. (However, the water hardness modulus (HM) is 1.1 to 1.3, the silicate modulus (SM) is 2.4 to 2.6, the iron modulus (IM) is 2.0 to 2.3, and aluminum oxide (Al 2 O 3 ) and iron oxide (Fe 2 O 3 (Excluding clinker powder having a mineral composition in which the total content of ) is 9.5 to 14.0% by mass.) A method for producing a cementitious hardened body using a cement composition containing gypsum and water, characterized in that it includes a carbonation curing step of carbonizing the cement composition to obtain the cementitious hardened body.

[0006] [2] The method for producing a cementitious hardened body according to [1], wherein the carbonation curing step is performed such that the carbonation depth from the surface of the cementitious hardened body is 2 mm or more. [3] The cement composition according to [1] or [2], wherein the cement composition contains Portland cement clinker powder, and the amount of clinker powder in 100 parts by mass of the total amount of clinker powder and Portland cement clinker powder is 50 parts by mass or more. [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a cement composition that can absorb more carbon dioxide during the curing process, thereby reducing the total amount of carbon dioxide emitted, and that exhibits excellent strength development. [Modes for carrying out the invention]

[0008] The clinker powder of the present invention has a mineral composition in which the hydraulic modulus (HM) is 1.1 to 2.0, the silicic acid modulus (SM) is 1.5 to 3.5, the iron modulus (IM) is 1.7 to 3.5, and the total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) is 9.0 to 14.0% by mass. The water hardness (HM) of the clinker powder is 1.1 to 2.0, preferably 1.2 to 1.9, more preferably 1.3 to 1.8, even more preferably 1.3 to 1.7, even more preferably 1.3 to 1.6, and particularly preferably 1.3 to 1.5. If the water hardness is less than 1.1, the strength development of the cement composition containing the clinker powder decreases. If the water hardness exceeds 2.0, the ease of firing of the clinker decreases, free lime (f·CaO) tends to remain, and it becomes necessary to raise the firing temperature when producing the clinker.

[0009] The silica modulus (S.M.) of the clinker powder is 1.5 to 3.5, preferably 1.6 to 3.3, more preferably 1.7 to 3.0, still more preferably 2.0 to 2.9, still more preferably 2.2 to 2.8, still more preferably 2.3 to 2.7, and particularly preferably 2.4 to 2.6. When the silica modulus is less than 1.5, the fluidity of a cement composition containing the clinker powder decreases. When the silica modulus exceeds 3.5, the burnability of clinker decreases, unreacted silica (SiO₂) tends to remain, and a higher firing temperature is required for producing clinker. The iron modulus (I.M.) of the clinker powder is 1.7 to 3.5, preferably 1.8 to 3.4, more preferably 1.9 to 3.3, still more preferably 2.0 to 2.4, and particularly preferably 2.0 to 2.3. When the iron modulus is less than 1.7, the strength development property of a cement composition containing the clinker powder decreases. When the iron modulus exceeds 3.5, the fluidity of a cement composition containing the clinker powder decreases.

[0010] The total content of aluminum oxide (Al₂O₃) and iron oxide (Fe₂O₃) in 100% by mass of the clinker powder is 9.0 to 14.0% by mass, preferably 9.5 to 13.0% by mass, more preferably 10.0 to 12.0% by mass, and particularly preferably 10.5 to 11.8% by mass. When the content is less than 9.0% by mass, carbonation hardly progresses to the inside of a hardened cementitious material, and the carbon dioxide absorption efficiency decreases. When the content exceeds 14.0% by mass, the amount of carbon dioxide that can be fixed by the cement composition containing the clinker powder becomes small.

[0011] An example of the method for producing the clinker powder of the present invention includes a first production method comprising: a firing step of firing a mixture of raw materials for firing at 1,250 to 1,500°C to obtain clinker; and a grinding step of grinding the clinker to obtain clinker powder. Hereinafter, each step will be described in detail. [Firing Step] This step is a step of firing the mixture of raw materials for firing at 1,250 to 1,500°C to obtain clinker. As the firing material, general raw materials used for manufacturing cement clinker may be used, such as calcium-containing raw materials (CaO sources) including limestone, quicklime, slaked lime and the like, silicon-containing raw materials (SiO₂ sources) including silica stone, clay and the like, aluminum-containing raw materials (Al₂O₃ sources) including clay and the like, and iron-containing raw materials (Fe₂O₃ sources) including iron slag, iron cake and the like.

[0012] In addition to the above raw materials, one or more types selected from industrial waste, general waste and construction generated soil may also be used. Here, industrial waste refers to waste generated along with business activities (excluding "construction generated soil" described later). Examples of industrial waste include ready-mixed concrete sludge, various types of sludge (e.g., sewage sludge, purified water sludge, iron-making sludge, etc.), construction waste, concrete waste, various types of incineration ash (e.g., coal ash, chicken manure ash, livestock manure ash, biomass ash, sludge incineration ash), foundry sand, rock wool, waste glass, blast furnace secondary ash, various by-products, unused resources (e.g., materials remaining unused), and the like. General waste refers to waste other than industrial waste (excluding "construction generated soil" described later). Examples of general waste include dried sewage sludge powder, municipal solid waste incineration ash, seashells, and the like. Examples of construction generated soil include soil and sediment secondarily generated at construction sites, work sites and the like (e.g., boring waste soil generated by ground excavation), surplus soil, waste soil, sludge (construction sludge; e.g., a mixture of cement milk and excavated soil generated in ground improvement work), and the like. A mixture of firing materials can be obtained by appropriately mixing these raw materials such that the hydraulic modulus, silica modulus, iron modulus, and total content of aluminum oxide and iron oxide in the obtained clinker powder fall within desired numerical ranges.

[0013] The firing temperature in the firing step is 1,250 to 1,500°C, preferably 1,260 to 1,400°C, more preferably 1,280 to 1,350°C. If the temperature is lower than 1,260°C, the amount of free lime in the clinker powder increases, and the strength development property of the cement composition containing the clinker powder decreases. If the temperature exceeds 1,500°C, the energy cost required for firing becomes excessive.

[0014] [Grinding process] This process involves grinding clinker to obtain clinker powder. The method of grinding the clinker is not particularly limited and can be carried out using a general method such as a ball mill.

[0015] Alternatively, the clinker powder of the present invention may be produced by mixing two or more types of clinker powder. Specifically, a second manufacturing method is mentioned, which includes a firing step of firing each of two or more firing material mixtures at 1,250 to 1,500°C to obtain two or more types of clinker; a grinding step of grinding two or more types of clinker to obtain two or more types of clinker powder for mixing; and a mixing step of mixing two or more types of clinker powder to obtain clinker powder. Each of the two or more firing material mixtures used in the above firing process can be obtained by appropriately mixing the above-mentioned firing materials such that the water hardness, silica content, iron content, and the total content of aluminum oxide and iron oxide in the clinker powder obtained in the mixing process are within a desired numerical range. The firing temperature is the same as the firing temperature in the firing step of the first manufacturing method described above (however, the above temperatures for each of the two or more firing material mixtures may be the same or different from each other).

[0016] Next, each of the two or more clinkers obtained in the calcination process is pulverized in the grinding process to obtain two or more clinker powders for mixing. Then, the two or more clinker powders for mixing are mixed in the mixing process to obtain the clinker powder of the present invention. The mixing ratio of the above clinker powders for mixing can be appropriately determined so that the water hardness, silica content, iron content, and the total content of aluminum oxide and iron oxide in the clinker powder obtained in the mixing process fall within a desired numerical range.

[0017] The cement composition of the present invention comprises the above-mentioned clinker powder, gypsum, and water. Examples of gypsum include anhydrous gypsum, dihydrate gypsum, hemihydrate gypsum, or mixtures thereof. The proportion of gypsum in the cement composition is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 4.0% by mass, and particularly preferably 1.0 to 3.0% by mass, in terms of SO3. If the above proportion is 0.1% by mass or more, the usable time (time during which good fluidity can be maintained) of the cement composition before hardening is increased. If the amount is 5.0% by mass or less, the strength development of the cement composition is improved.

[0018] The water used in this invention is not particularly limited, and examples include tap water and sludge water. The amount of water used is not particularly limited and can be any amount that is typical for pastes, mortars, or concretes. For example, the amount of water used is such that the mass ratio of water to cement composition (water / cement composition) is preferably 0.20 to 0.60, more preferably 0.23 to 0.50, and particularly preferably 0.23 to 0.40. If the above ratio is 0.20 or higher, workability is further improved. If the above ratio is 0.60 or lower, the strength development of the cement composition is further improved.

[0019] The cement composition may contain Portland cement clinker powder, from the viewpoint of ease of availability and improvement of strength development. The Portland cement clinker powder is not particularly limited, and various types of Portland cement clinker powders can be used, such as ordinary Portland cement clinker, rapid-strength Portland cement clinker, moderate-heat Portland cement clinker, and low-heat Portland cement clinker. The amount of the above-mentioned clinker powder in a total of 100 parts by mass of the above-mentioned clinker powder and Portland cement clinker powder is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and particularly preferably 70 parts by mass or more. If the above amount is 50 parts by mass or more, more carbon dioxide can be absorbed during the curing process.

[0020] The cement composition of the present invention may contain other materials as needed. Other materials that may be added as needed include: (i) aggregates such as fine aggregate, coarse aggregate, and lightweight aggregate; (ii) various admixtures such as AE agents, water-reducing agents, high-performance water-reducing agents, and high-performance water-reducing agents; (iii) various admixtures such as fly ash, silica fume, blast furnace slag fine powder, and siliceous mixtures (excluding silica fume); and (iv) fibers such as organic fibers and glass fibers.

[0021] The method for producing a cementitious hardened body using the cement composition of the present invention is not particularly limited, and any general method for producing paste, mortar, or concrete may be used. However, from the viewpoint of absorbing more carbon dioxide, a method including a carbonation curing step in which the cement composition is carbonized to obtain a cementitious hardened body is preferred. The cement composition is, for example, poured into formwork after the individual components of the cement composition are mixed using a conventional mixer before the carbonation curing process. The concentration of carbon dioxide gas in the carbonation curing process is preferably 1% by volume or more, 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 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 costs associated with curing equipment, etc., it is preferably 90% by volume or less, more preferably 85% by volume or less, and particularly preferably 80% by volume or less.

[0022] Furthermore, the temperature in the carbonation curing process is not particularly limited, but is preferably 5 to 100°C, more preferably 10 to 70°C, even more preferably 15 to 50°C, and most preferably 20 to 35°C. If the above temperature is 5°C or higher, the productivity of the cementitious hardened material is further improved and the strength of the cementitious hardened material is increased. If the above temperature exceeds 100°C, the energy cost of carbonation curing becomes excessive. Furthermore, while the relative humidity in the carbonation curing process is not particularly limited, it 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 cementitious hardened material is further improved, and the strength of the cementitious hardened material is increased. It is difficult to raise the relative humidity above 90%, and the costs associated with equipment, etc., become excessive.

[0023] In the carbonation curing process, it is preferable to perform carbonation curing so that the carbonation depth from the surface of the cementitious hardened body is preferably 2 mm or more, more preferably 3 mm or more, even more preferably 4 mm or more, and particularly preferably 5 mm or more. By performing carbonation curing to a carbonation depth of 2 mm or more, a larger amount of carbon dioxide can be absorbed by the cement composition. 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 cementitious body" can be measured in accordance with "JIS A 1152:2018 (Method for measuring the carbonation depth of concrete)." The resulting cementitious hardened material can be used as roadbed material, interlocking blocks, artificial reef blocks, wave-dissipating blocks, drainage ditch blocks, planting concrete, manholes, roadway boundary blocks, drainage ditches, or high-strength external pressure pipes, etc. Furthermore, even after being installed as roadbed material, etc., it can continue to absorb and fix carbon dioxide. [Examples]

[0024] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Manufacturing of cement composition A] A mixture of calcination materials was prepared using calcium-containing raw materials, silicon-containing raw materials, aluminum-containing raw materials, and iron-containing raw materials, with the blending ratios determined so that the chemical composition of the clinker powder would match the values ​​shown in Table 1. The calcination material mixture was calcined at 1,300°C for 30 minutes to obtain clinker, which was then pulverized to produce clinker powder A. The Blaine specific surface area of ​​clinker powder A was 5,000 cm². 2 The result was / g. The obtained clinker powder A was used as cement composition A. The SO3 content in cement composition A was 0.6% by mass (100% by mass).

[0025] [Manufacturing of cement composition B] Clinker was produced in the same manner as clinker powder A, except that the chemical composition of the clinker powder was determined to match the values ​​in Table 1. The obtained clinker and dihydrate gypsum were mixed and ground to obtain cement composition B (a mixture of clinker powder B and gypsum) with an SO3 content of 2.0% by mass. The Blaine specific surface area of ​​the obtained cement composition B was 5,000 cm². 2 It was / g. [Manufacturing of cement composition C] Clinker was produced in the same manner as clinker powder A, except that the chemical composition of the clinker powder was determined to match the values ​​in Table 1. The obtained clinker and dihydrate gypsum were mixed and ground to obtain cement composition C (a mixture of clinker powder C and gypsum) with an SO3 content of 2.0% by mass. The Blaine specific surface area of ​​the obtained cement composition C was 3,000 cm². 2 It was / g.

[0026] [Manufacturing of cement composition D] Cement composition A and cement composition C were mixed to produce cement composition D (a mixture of cement composition A and cement composition C) such that cement composition A and cement composition C each contained 50% by mass. The chemical composition of clinker powder D contained in cement composition D is shown in Table 1. The SO3 content in cement composition D was 1.3% by mass. [Manufacturing of cement composition E] Cement composition A and cement composition C were mixed to produce cement composition E (a mixture of cement composition A and cement composition C) such that cement composition A contained 75% by mass and cement composition C contained 25% by mass. The chemical composition of clinker powder E contained in cement composition E is shown in Table 1. The SO3 content in cement composition E was 1.0%.

[0027] [Manufacturing of cement composition F] Cement composition B and cement composition C were mixed to produce cement composition F (a mixture of cement composition B and cement composition C) such that cement composition B accounted for 75% by mass and cement composition C accounted for 25% by mass. The chemical composition of clinker powder F contained in cement composition F is shown in Table 1. The SO3 content in cement composition F was 2.0% by mass. [Manufacturing of cement composition G] Clinker was produced in the same manner as clinker powder A, except that the chemical composition of the clinker powder was determined to match the values ​​in Table 1. The obtained clinker and dihydrate gypsum were mixed and ground to obtain cement composition G (a mixture of clinker powder G and gypsum) with an SO3 content of 2.0% by mass. The Blaine specific surface area of ​​the obtained cement composition G was 4,000 cm². 2 It was / g.

[0028] [Manufacturing of cement composition H] A mixture of calcination materials was prepared using calcium-containing raw materials, silicon-containing raw materials, aluminum-containing raw materials, and iron-containing raw materials, with the blending ratios determined so that the chemical composition of the clinker powder would match the values ​​shown in Table 1. The calcination material mixture was calcined at 1,450°C for 1 hour to obtain clinker. The obtained clinker was pulverized to produce clinker powder H. The Blaine specific surface area of ​​clinker powder H was 3,200 cm². 2 The result was / g. The obtained clinker powder H was used as cement composition H. The SO3 content in 100% by mass of cement composition H was 2.0% by mass. Table 1 also shows the hydraulic ratio, silicate ratio, and iron ratio of clinker powders A to H contained in cement compositions A to H.

[0029] [Table 1]

[0030] [Examples 1-7, Comparative Example 1] The types of cement compositions shown in Table 2, along with water, fine aggregate (mountain sand), and coarse aggregate (crushed stone No. 7), were added to an Einrich mixer in the following order: coarse aggregate, half the total amount of fine aggregate, cement composition, and the remaining fine aggregate. Dry mixing was then performed. Next, while mixing each material, water pre-mixed with a high-performance water-reducing agent (BASF Japan, product name "Master Glenium 8000SM") was added over 30 seconds, and the mixture was further mixed for 60 seconds to prepare fresh concrete. The unit amounts of each material were set to the amounts shown in Table 2. The obtained fresh concrete was placed into a high-vibration pressure molding machine (Gokosha, GK8-B model) and pressure-molded to produce test specimens. The dimensions of the test specimens were 200 mm in length and 100 mm in width, with a target height of 80 mm after molding. The molded specimens, along with their base plates, were placed in a constant temperature chamber at 30°C, 60% relative humidity, and 80% by volume of carbon dioxide for 7 days of carbonation curing. The following evaluation methods were used with the cured specimens (hardened cementitious bodies). The results are shown in Table 3.

[0031] [Bending strength] Bending strength tests were conducted in accordance with "JIS A 5371:2016 (Precast Unreinforced Concrete Products, Annex B (Normative), Pavement and Boundary Blocks, Recommended Specification B-3 Interlocking Blocks)". The bending strength of specimens was measured at 3 and 7 days of age, starting from the day of molding. The loading span during measurement was 160 mm, and the increase in edge stress was 0.8 to 1.0 N / mm² per minute. 2 The loading speed was adjusted to achieve this result. Three specimens were used for each age stage, and the average value was used as the measurement value.

[0032] [Carbonation depth] For specimens aged 3 days and 7 days, after flexural strength measurements had been completed, a 1% phenolphthalein ethanol solution was sprayed onto the fracture surface of the specimen in accordance with "JIS A 1152:2018 (Method for measuring the carbonation depth of concrete)". After more than 4 hours, the carbonation depth on the pressure-molded surface side (the area that turned color due to the spraying of the 1% phenolphthalein ethanol solution) was measured using calipers, and this was taken as the carbonation depth value. Measurements were taken at five equally spaced points in the area excluding a range of approximately 10 mm from the corners of the specimen, and the average value of the obtained carbonation depths was taken as the measured value. Specimens where the entire fracture surface turned color are indicated as "complete carbonation" in Table 3.

[0033] [Carbon dioxide fixation amount] For each specimen after measurement of the carbonation depth, the portion relatively close to the fracture surface was cut perpendicular to the long side using a concrete cutter, and the specimen was processed into a plate approximately 10 mm thick. The plate-shaped specimens were dried under atmospheric pressure until the surface was dry, then transferred to a vacuum dryer and dried under reduced pressure for more than 24 hours. Subsequently, the entire volume was finely pulverized using a vibrating disc mill, and then thermogravimetric analysis was performed using a TG-DTA apparatus. Based on the analysis results, the weight loss observed in the range of 600-800°C was considered to be due to the decarboxylation of CO2, and the amount of carbon dioxide fixed (indicated as "CO2 fixed amount" in Table 3) was calculated by dividing this by the amount of binder used in the specimen.

[0034] [Table 2]

[0035] [Table 3]

[0036] Table 3 shows the flexural strength of the cementitious hardened materials of Examples 1-7 (3 days old: 3.4-5.3 N / mm²). 2 , material age 7 days: 3.7~5.6N / mm 2) is 3.0 N / mm 2 or higher. From this, it can be seen that the above cementitious hardened product satisfies the flexural strength of 3.0 N / mm 2 ) specified for normal block N (those mainly used for sidewalks) in Recommended Specification B-3 Interlocking Blocks of JIS A 5371:2010 (Precast unreinforced concrete products). Further, the carbonation depths of Examples 1 to 7 (age 3 days: 4.8 mm to complete neutralization; age 7 days: 6.4 mm to complete neutralization) are larger than the carbonation depth of Comparative Example 1 (age 3 days: 1.9 mm; age 7 days: 3.3 mm), and it can be seen that carbonation of the hardened product of the cement composition proceeds more sufficiently. Furthermore, the carbon dioxide fixation amount at 7 days of age of Examples 1 to 7 (128 to 227 kg / ton) is larger than the carbon dioxide fixation amount at 7 days of age of Comparative Example 1 (120 kg / ton), and it can be seen that the hardened product of the cement composition absorbed more carbon dioxide.

Claims

1. The water hardness (H.M.) is 1.1 to 2.0, the silicate content (S.M.) is 1.5 to 3.5, the iron content (I.M.) is 1.7 to 3.5, and aluminum oxide (Al ２ O ３ ) and iron oxide (Fe ２ O ３ Clinker powder having a mineral composition in which the total content of ) is 9.0 to 14.0% by mass (however, the hydraulic modulus (H.M.) is 1.1 to 1.3, the silicic acid modulus (S.M.) is 2.4 to 2.6, the iron modulus (I.M.) is 2.0 to 2.3, and aluminum oxide (Al ２ O ３ ) and iron oxide (Fe ２ O ３ A method for producing a cementitious hardened body using a cement composition containing clinker powder having a mineral composition in which the total content of ) is 9.5 to 14.0% by mass, gypsum, and water, A method for producing a cementitious hardened body, characterized by including a carbonation curing step of carbonizing the above-mentioned cement composition to obtain the above-mentioned cementitious hardened body.

2. The method for producing a cementitious hardened body according to claim 1, wherein the carbonation curing step is performed such that the carbonation depth from the surface of the cementitious hardened body is 2 mm or more.

3. The above cement composition contains Portland cement clinker powder, A method for producing a cementitious hardened body according to claim 1 or 2, wherein the amount of the clinker powder in the total amount of the above clinker powder and the above Portland cement clinker powder is 50 parts by mass or more, in a total of 100 parts by mass.

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