Method for producing hydraulic hardened body

Abstract

To provide a method for producing a hydraulic hardened body, which reduces the amount of energy consumption and the amount of CO2 discharge in material production and is excellent in producibility of a precast product.SOLUTION: A method for producing a hydraulic hardened body includes kneading and hardening a hydraulic composition containing a binder (A), an admixture (B), water, an aggregate, and an admixture, wherein the proportion of the admixture (B) in the total of the binder (A) and the admixture (B) is 2 mass% to 10 mass%. In the binder (A), the proportion of the high-early-strength portland cement is 20 mass% to 55 mass%, the proportion of the blast furnace slag fine powder is 45 mass% to 75 mass%, and the total of these two components accounts for 90 mass% or more of the whole. The admixture (B) contains organic calcium salts, inorganic calcium compounds, and inorganic sulfates, and has a CaO content of 53 mass% to 58 mass%, a SO3 content of 15 mass% to 20 mass%, a total alkali content of 2.5 mass% to 2.8 mass%, and an ignition loss of 20 mass% to 25 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a hydraulically cured body. [Background technology]

[0002] Cement consumes a large amount of energy and emits a large amount of CO2 during the firing process. If the amount of cement in a hydraulic composition can be reduced, the amount of energy consumed and CO2 emitted during the production of materials for the hydraulic composition and hydraulic hardened body can be reduced.

[0003] In order to reduce energy consumption and CO2 emissions during material production, hydraulic compositions containing a high content of ground granulated blast furnace slag as a binder have been developed. For example, Patent Document 1 discloses a concrete composition containing a specified blast furnace cement, water, fine aggregate, coarse aggregate, and a specified admixture. For example, Patent Document 2 discloses a concrete composition containing blast furnace cement, water, fine aggregate, coarse aggregate, a predetermined admixture, and an air content adjuster.

[0004] Hydraulic hardening precast products are used at construction sites to shorten construction times and streamline work. To improve productivity, precast products are required to develop compressive strength in a short time so that they can be demolded. Early strength shortages lead to reduced productivity of precast products.

[0005] In order to develop compressive strength sufficient for demolding in a short time, hardening accelerators for hydraulic hardened bodies have been developed. For example, Patent Documents 3 and 4 disclose a hardening accelerator for hydraulic materials containing 10% by mass to 30% by mass of inorganic sulfate, 10% by mass to 70% by mass of calcium sulfoaluminate, and 10% by mass to 30% by mass of inorganic hydroxide. For example, Patent Documents 5 and 6 disclose a hardening accelerator for hydraulic materials that contains 1% by mass to 65% by mass of calcium sulfoaluminate, 0.5% by mass to 75% by mass of an organic acid calcium salt, 1% by mass to 55% by mass of an inorganic calcium compound, and 0.5% by mass to 45% by mass of an inorganic sulfate other than calcium sulfate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-203635 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-203636 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-019618 [Patent Document 4] Japanese Patent Publication No. 2023-090515 [Patent Document 5] Japanese Patent Application Publication No. 2024-033209 [Patent Document 6] International Publication No. 2024 / 048364 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to provide a method for producing a hydraulic hardened body that reduces energy consumption and CO2 emissions during material production and has excellent productivity for precast products. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects: Each formula is the same as the formula with the same number described below.

[0009] <1> A step of kneading a hydraulic composition containing the following binder (A), the following admixture (B), water, aggregate, and admixture, wherein the proportion of the following admixture (B) in the total of the following binder (A) and the following admixture (B) is 2% by mass to 10% by mass; A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of 30 cm to 150 cm among width, length, and height; and a curing step of steam curing the hydraulic composition cast into the formwork at a temperature of 50°C to 95°C for 2.0 hours to 5.0 hours. A method for producing a hydraulic cured body. Binder (A): A binder containing high-early-strength Portland cement and ground granulated blast furnace slag, wherein the proportion of the high-early-strength Portland cement is 20% by mass to 55% by mass, the proportion of the ground granulated blast furnace slag is 45% by mass to 75% by mass, and the total of the high-early-strength Portland cement and the ground granulated blast furnace slag accounts for 90% by mass or more of the total. Admixture (B): An admixture containing an organic calcium salt, an inorganic calcium compound, and an inorganic sulfate, in which the CaO content is 53% by mass to 58% by mass, the SO3 content is 15% by mass to 20% by mass, the total alkali content is 2.5% by mass to 2.8% by mass, and the loss on ignition is 20% by mass to 25% by mass. <2> A step of kneading a hydraulic composition containing the following binder (A), the following admixture (B), water, aggregate, and admixture, wherein the proportion of the following admixture (B) in the total of the following binder (A) and the following admixture (B) is 2% by mass to 10% by mass; A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of width, length, and height of less than 30 cm; a first curing step of steam curing the hydraulic composition cast into the formwork at a temperature of 30°C to 48°C for 0.6 hours to 1.5 hours; a second curing step of steam curing the hydraulic composition that has been subjected to the first curing step at a temperature of 60°C to 85°C for 0.8 hours to 2.0 hours; A method for producing a hydraulic cured body. Binder (A): A binder containing high-early-strength Portland cement and ground granulated blast furnace slag, wherein the proportion of the high-early-strength Portland cement is 20% by mass to 55% by mass, the proportion of the ground granulated blast furnace slag is 45% by mass to 75% by mass, and the total of the high-early-strength Portland cement and the ground granulated blast furnace slag accounts for 90% by mass or more of the total. Admixture (B): An admixture containing an organic calcium salt, an inorganic calcium compound, and an inorganic sulfate, in which the CaO content is 53% by mass to 58% by mass, the SO3 content is 15% by mass to 20% by mass, the total alkali content is 2.5% by mass to 2.8% by mass, and the loss on ignition is 20% by mass to 25% by mass. <3> The binder (A) contains a sulfate, and the proportion of the sulfate in the binder (A) is 1% by mass to 5% by mass in terms of SO3. <1> or <2> A method for producing the hydraulically hardened body described above. <4> The admixture comprises the following vinyl copolymer (C): <1> ~ <3> 10. A method for producing a hydraulically hardened body according to any one of the above. Vinyl copolymer (C): A vinyl copolymer having a structural unit (1) derived from a monomer (1) represented by formula (1) and a structural unit (2) derived from at least one monomer (2) selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, and salts thereof, wherein the mass ratio of the structural unit (1) to the structural unit (2) is 75:25 to 95:5 and the mass average molecular weight is 5,000 to 200,000. [Effects of the Invention]

[0010] According to the present disclosure, a method for producing a hydraulic hardened body is provided that reduces energy consumption and CO2 emissions during material production and has excellent productivity for precast products. [Brief explanation of the drawings]

[0011] [Figure 1] 10 is a graph showing the compressive strength of test specimens in Experiment 2. [Figure 2] 10 is a graph showing the temperature history of steam curing in Experiment 3. [Figure 3] 10 is a graph showing the compressive strength of test specimens in Experiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0023] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0013] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples.

[0014] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0015] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0016] In the present disclosure, when referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0017] In the present disclosure, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and means that either is acceptable. "(meth)acrylate" is an expression that includes both acrylate and methacrylate, and means that either is acceptable.

[0018] <Method for producing hydraulic cured body> The present disclosure provides a method for producing a hydraulic hardened body using a specific hydraulic composition, with the aim of reducing energy consumption and CO2 emissions during the production of materials for the hydraulic hardened body. The hydraulic composition will be described in detail below.

[0019] The present disclosure provides a manufacturing method for improving the productivity of precast products, by which a hydraulically hardened body develops compressive strength that allows it to be demolded in a short period of time.

[0020] To increase the productivity of precast products, it is desirable to carry out the curing process at a relatively high temperature so that the compressive strength required for demolding can be achieved in a short time. However, since the internal temperature of relatively small components is likely to reflect the ambient temperature, if the temperature is set high in the early stages of curing, the reaction of the hydraulic composition will proceed rapidly, and although the compressive strength required for demolding can be achieved in a short time, the structure of the hardened body may be affected. Therefore, the manufacturing method of the hydraulic hardened body is divided into two types depending on the size of the formwork into which the hydraulic composition is cast, and appropriate curing is performed for each type. The first type is a manufacturing method applicable when formwork whose minimum dimensions among width, length, and height are 30 cm to 150 cm is used. The second type is a manufacturing method applicable when formwork whose minimum dimensions among width, length, and height are less than 30 cm is used.

[0021] A method for producing a hydraulic hardened body according to a first embodiment includes the steps of: A step of kneading the hydraulic composition of the present disclosure (kneading step); A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of 30 cm to 150 cm among width, length, and height (a pouring step); and a curing step of steam curing the hydraulic composition cast into the formwork at a temperature of 50°C to 95°C for 2.0 to 5.0 hours.

[0022] A method for producing a hydraulic hardened body according to a second embodiment includes the steps of: A step of kneading the hydraulic composition of the present disclosure (kneading step); A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of less than 30 cm among width, length, and height (a pouring step); a first curing step of steam curing the hydraulic composition poured into the formwork at a temperature of 30°C to 48°C for 0.6 to 1.5 hours; The method includes a second curing step in which the hydraulic composition that has been subjected to the first curing step is steam cured at a temperature of 60°C to 85°C for 0.8 to 2.0 hours.

[0023] The first method is used to manufacture relatively large components, and involves steam curing at a relatively high temperature from the early stage of curing, thereby developing compressive strength sufficient for demolding in a short period of time.

[0024] The second method is used to produce relatively small components, and involves steam curing at a relatively low temperature in the early stages of curing, followed by steam curing at a relatively high temperature after the structure has stabilized. This allows the precast product to develop sufficient compressive strength to be demolded in a short period of time, while improving the quality of the precast product.

[0025] In both the first and second embodiments, the mixing and placing steps may be carried out in accordance with conventional methods. The curing steps of the first and second embodiments will be described in detail below.

[0026] [Curing step in the first embodiment] This step involves steam curing at a temperature of 50°C to 95°C for 2.0 to 5.0 hours. The temperature here refers to the atmospheric temperature at which steam curing is performed. The atmospheric temperature may be constant or may fluctuate during the curing step.

[0027] When manufacturing a relatively large member, it takes time for the temperature of the center of the hydraulic composition to reach the desired temperature, so curing is carried out at a temperature of 50°C or higher from the initial stage of curing. The curing temperature is 50°C to 95°C, and preferably 60°C to 90°C. From the viewpoint of productivity of precast products, the appropriate curing time is 2.0 to 5.0 hours, and it may be set within this range depending on the size of the formwork and the curing temperature.

[0028] In one embodiment of the curing step, the temperature is increased 0.1 to 1.0 hour after casting the formwork, and is raised to 50 to 95°C at a rate of 0.2 to 5.0°C / min. According to this embodiment, the rate of internal temperature rise in a pillar with a diameter of 100 cm to 150 cm is approximately 0.3°C / min to 0.5°C / min at a depth of 3 cm from the surface, and approximately 0.1°C / min to 0.2°C / min at the center.

[0029] [Curing process in the second embodiment] In the second form, two stages of steam curing are carried out at different temperatures. The first curing step is a step of performing steam curing at a temperature of 30°C to 48°C for 0.6 to 1.5 hours. The second curing step is a step of performing steam curing at a temperature of 60°C to 85°C for 0.8 to 2.0 hours. The temperature here refers to the ambient temperature at which steam curing is carried out. The ambient temperature may be constant or may fluctuate during the curing process.

[0030] When manufacturing relatively small components, if the temperature is set too high in the early stages of curing, the reaction of the hydraulic composition will proceed too quickly, affecting the structure of the hardened body and potentially resulting in insufficient long-term product strength. Furthermore, when manufacturing relatively small components, if the temperature is set too high in the early stages of curing, the volume of the hydraulic composition will expand too rapidly, potentially resulting in cracks due to volumetric shrinkage after curing. To prevent these issues, the two-stage steam curing described above is used when manufacturing relatively small components. That is, the first curing step at a relatively low temperature allows the setting of the hydraulic composition to proceed slowly, and after the structure has stabilized, the second curing step at a relatively high temperature promotes the hydration reaction of the hydraulic composition, allowing it to develop compressive strength that allows it to be demolded in a short period of time.

[0031] The temperature in the first curing step is 30° C. to 48° C., preferably 30° C. to 45° C. The curing time is 0.6 to 1.5 hours, preferably 0.9 to 1.3 hours.

[0032] In one embodiment of the first curing step, the temperature is increased 0.1 to 1.0 hour after casting the formwork, and is increased to 30 to 48°C at a rate of 5 to 10°C / min.

[0033] The temperature in the second curing step is 60° C. to 85° C., preferably 70° C. to 80° C. The curing time is 0.8 to 2.0 hours, and may be set within this range depending on the size of the formwork and the curing temperature.

[0034] In one embodiment of the second curing step, the temperature is raised from the temperature achieved in the first curing step to a temperature of 60°C to 85°C at a rate of 0.2°C / min to 1.4°C / min. According to this embodiment, the internal temperature rise rate for a 20cm thick slab member is approximately 0.1°C / min to 1.0°C / min.

[0035] In both the first and second embodiments, the hydraulically hardened body is demolded after the curing step. The demolded hydraulically hardened body may be left in the air. A known curing agent may be applied to the surface of the demolded hydraulically hardened body. The demolded hydraulically hardened body may be covered with a sheet.

[0036] <Hydraulic composition> The present disclosure provides the following hydraulic composition for the purpose of reducing energy consumption and CO2 emissions during the production of materials for hydraulically set bodies and improving the productivity of precast products. The method for producing a hydraulically set body of the present disclosure uses the following hydraulic composition.

[0037] The hydraulic composition of the present disclosure contains a binder (A), an admixture (B), water, aggregate, and an admixture, and the proportion of the admixture (B) in the total of the binder (A) and the admixture (B) is 2% by mass to 10% by mass.

[0038] Binder (A): A binder containing high-early-strength Portland cement and ground granulated blast furnace slag, in which the proportion of high-early-strength Portland cement is 20% by mass to 55% by mass, the proportion of ground granulated blast furnace slag is 45% by mass to 75% by mass, and the total of the high-early-strength Portland cement and ground granulated blast furnace slag accounts for 90% by mass or more of the total.

[0039] Admixture (B): An admixture containing an organic calcium salt, an inorganic calcium compound, and an inorganic sulfate, in which the CaO content is 53% by mass to 58% by mass, the SO3 content is 15% by mass to 20% by mass, the total alkali content is 2.5% by mass to 2.8% by mass, and the loss on ignition is 20% by mass to 25% by mass.

[0040] Precast products are required to quickly develop sufficient mechanical strength to be able to be lifted out of the formwork and transported immediately after removal. Insufficient mechanical strength in the early stages leads to reduced productivity of precast products. The inventors used high-early-strength Portland cement as the cement type for producing precast products in the hope of quickly developing mechanical strength, and attempted to replace most of the high-early-strength Portland cement with ground granulated blast furnace slag in order to reduce energy consumption and CO2 emissions during material production. As shown in Experiment 1 below, they found that combining an admixture with a specific chemical composition quickly developed compressive strength sufficient for demolding. As is clear from Experiment 1, when most of the high-early-strength Portland cement was replaced with ground granulated blast furnace slag and an admixture with a specific chemical composition was mixed, compressive strength sufficient for demolding and transportation quickly developed.

[0041] Therefore, the present disclosure provides a hydraulic composition and a hydraulically set body that reduce energy consumption and CO2 emissions during material production and have excellent productivity for precast products.

[0042] In the hydraulic composition of the present disclosure, the proportion of the admixture (B) in the total of the binder (A) and the admixture (B) is 2% by mass to 10% by mass. If the proportion of the admixture (B) is less than 2% by mass, the development of strength sufficient for demolding may not be as rapid as expected. From the viewpoint of accelerating the development of strength sufficient for demolding and increasing the productivity of precast products, the proportion of the admixture (B) is 2% by mass or more, preferably 3% by mass or more, and more preferably 4% by mass or more. If the proportion of the admixture (B) exceeds 10% by mass, the quality and long-term strength of the precast product may be poor. From the viewpoint of ensuring the quality and long-term strength of the precast product, the proportion of the admixture (B) is 10% by mass or less, preferably 8% by mass or less, and more preferably 6% by mass or less.

[0043] The materials constituting the hydraulic composition of the present disclosure will be described in detail below.

[0044] [Binding material (A)] The binder (A) contains at least high-early-strength Portland cement and ground granulated blast furnace slag, and the total of the high-early-strength Portland cement and ground granulated blast furnace slag accounts for 90% by mass or more of the binder. The total of the high-early-strength Portland cement and ground granulated blast furnace slag may be 95% by mass or more, or may be 100% by mass, of the binder (A).

[0045] The proportion of high-early-strength Portland cement in the binder (A) is preferably as high as possible, from the viewpoint of ensuring the quality and long-term strength of the precast product. The proportion of high-early-strength Portland cement in the binder (A) is preferably low from the viewpoint of reducing energy consumption and CO2 emissions during the production of the hydraulic composition material. The proportion of high-early-strength Portland cement in the binder (A) is 20% by mass to 55% by mass, preferably 20% by mass to 50% by mass, more preferably 20% by mass to 45% by mass, and even more preferably 25% by mass to 40% by mass.

[0046] The proportion of ground granulated blast furnace slag in the binder (A) is preferably as high as possible from the viewpoint of reducing energy consumption and CO2 emissions during the production of the hydraulic composition material. It is preferable that the proportion of ground granulated blast furnace slag in the binder (A) is not too high, from the viewpoint of ensuring the quality and long-term strength of the precast product. The proportion of ground granulated blast furnace slag in the binder (A) is 45% by mass to 75% by mass, preferably 50% by mass to 75% by mass, more preferably 55% by mass to 75% by mass, and even more preferably 60% by mass to 70% by mass.

[0047] The quality of the ground blast furnace slag (e.g., density, specific surface area) is not limited, and may be selected depending on the target fluidity and workability of the hydraulic composition and the target mechanical strength of the hydraulic hardened body. Examples of ground granulated blast furnace slag include ground granulated blast furnace slag 3000, 4000, 6000, and 8000 as specified in JIS A6206:2013 "ground granulated blast furnace slag for concrete."

[0048] From the viewpoint of achieving a balance between the development of compressive strength that allows demolding in a short period of time and the long-term strength of the product, the binder (A) preferably has a sulfate content of 1 to 5 mass % in terms of SO3, and more preferably 1.5 to 4.5 mass %. The sulfates contained in the binder (A) are the sum of sulfates brought in by the high-early-strength Portland cement, sulfates brought in by ground granulated blast furnace slag, and sulfates brought in by components other than the high-early-strength Portland cement and ground granulated blast furnace slag.

[0049] The binder (A) may contain components other than high-early-strength Portland cement and ground granulated blast furnace slag. Examples of such components include gypsum. The gypsum is added, for example, to adjust the sulfate content of the binder (A). The gypsum may be any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, and one type may be used alone, or two or more types may be used in combination. When the binder (A) contains gypsum, the proportion of gypsum in the binder (A) is preferably 1% by mass to 10% by mass, and more preferably 1% by mass to 5% by mass, calculated as SO3.

[0050] [Admixture (B)] The admixture (B) contains an organic calcium salt, an inorganic calcium compound, and an inorganic sulfate, and has a CaO content of 53% to 58% by mass, a SO3 content of 15% to 20% by mass, a total alkali content of 2.5% to 2.8% by mass, and an ignition loss of 20% to 25% by mass. The CaO amount and SO3 amount of the admixture (B) are values ​​evaluating the admixture (B) as a whole. The total alkali content and ignition loss of the admixture (B) are values ​​measured using the admixture (B) as a sample.

[0051] The admixture (B) has a CaO content of 53 mass % to 58 mass %. If the CaO content is less than 53 mass%, the desired strength cannot be obtained. From the viewpoint of obtaining the desired strength, the CaO content is 53 mass% or more, preferably 53.5 mass% or more, and more preferably 54.0 mass% or more. If the CaO content exceeds 58% by mass, the fluidity and workability of fresh concrete will decrease. From the viewpoint of improving the fluidity and workability of fresh concrete, the CaO content is 58% by mass or less, preferably 57.5% by mass or less, and more preferably 57.0% by mass or less.

[0052] The admixture (B) has an SO3 content of 15% by mass to 20% by mass. If the amount of SO3 is less than 15 mass%, the desired strength cannot be obtained. From the viewpoint of obtaining the desired strength, the amount of SO3 is 15 mass% or more, preferably 16.5 mass% or more, and more preferably 17.0 mass% or more. If the amount of SO3 exceeds 20% by mass, delayed expansion and / or reduced resistance to sulfate deterioration occurs. From the viewpoint of suppressing this phenomenon, the amount of SO3 is 20% by mass or less, preferably 19.5% by mass or less, and more preferably 19.0% by mass or less.

[0053] The admixture (B) has a total alkali content of 2.5% by mass to 2.8% by mass. The total alkali content of the admixture (B) is the total alkali content specified in JIS R5210:2019 "Portland cement" and is a value measured and calculated in accordance with the JIS standard. If the total alkali content is less than 2.5 mass%, the desired strength cannot be obtained. From the viewpoint of obtaining the desired strength, the total alkali content is 2.5 mass% or more, preferably 2.53 mass% or more, and more preferably 2.55 mass% or more. If the total alkali content exceeds 2.8% by mass, delayed expansion and / or alkali-aggregate reaction may occur. To prevent this, the total alkali content is set to 2.8% by mass or less, preferably 2.78% by mass or less, and more preferably 2.75% by mass or less.

[0054] The admixture (B) has an ignition loss of 20% to 25% by mass. If the loss on ignition is less than 20% by mass, it becomes difficult to adjust the fluidity and workability of fresh concrete. From the viewpoint of adjusting the fluidity and workability of fresh concrete to the desired range, the loss on ignition is 20% by mass or more, preferably 20.5% by mass or more, and more preferably 21.0% by mass or more. If the loss on ignition exceeds 25% by mass, it becomes difficult to adjust the fluidity and workability of fresh concrete. From the viewpoint of adjusting the fluidity and workability of fresh concrete to the desired range, the loss on ignition is 25% by mass or less, preferably 24.5% by mass or less, and more preferably 24.0% by mass or less. The ignition loss of the admixture (B) is the weight loss at temperatures of 20°C to 950°C determined by thermogravimetric analysis.

[0055] -Organic calcium salt- Examples of organic calcium salts include calcium formate, calcium acetate, and calcium lactate. These may be used alone or in combination of two or more. From the viewpoint of allowing the hydraulic composition to develop compressive strength sufficient to enable demolding in a short period of time, at least one of calcium formate and calcium acetate is preferred, and calcium formate is more preferred.

[0056] -Inorganic calcium compounds- Examples of inorganic calcium compounds include calcium sulfate, calcium hydroxide, calcium carbonate, and calcium oxide. These may be used alone or in combination of two or more. From the viewpoint of the hydraulic composition developing compressive strength sufficient to enable demolding in a short time, at least one of calcium sulfate and calcium hydroxide is preferred, calcium sulfate is more preferred, and calcium sulfate anhydride is even more preferred.

[0057] -Inorganic sulfates- Examples of inorganic sulfates include sulfates, thiosulfates, sulfites, bisulfites, pyrosulfates, and pyrobisulfites. The inorganic substance that forms the salt is preferably at least one of sodium, potassium, and aluminum, more preferably sodium. These may be used alone or in combination of two or more. From the viewpoint of the hydraulic composition developing compressive strength sufficient for demolding in a short time, at least one of sulfates and thiosulfates is preferred, at least one of sodium sulfate, aluminum sulfate, sodium thiosulfate, and potassium alum (potassium aluminum sulfate) is more preferred, and at least one of sodium sulfate and aluminum sulfate is even more preferred. Furthermore, from the viewpoint of the fluidity of the hydraulic composition, sodium sulfate is preferred, and anhydrous sodium sulfate is more preferred. In this embodiment, with regard to the admixture (B), calcium sulfate is included in the category of inorganic calcium compounds, but is not included in the category of inorganic sulfates.

[0058] -Other ingredients- The admixture (B) may contain components other than the organic calcium salt, inorganic calcium compound, and inorganic sulfate, such as calcium sulfoaluminate.

[0059] In this disclosure, calcium sulfoaluminate is a general term for hydraulic substances and hydrated salts represented by the chemical formula xCaO·yAl2O3·zCaSO4·mH2O (x, y, and z are positive real numbers other than 0, and m is 0 or a positive real number).

[0060] Examples of calcium sulfoaluminates include auyn (3CaO·3Al2O3·CaSO4), AFt phases such as ettringite (3CaO·Al2O3·3CaSO4·32H2O), AFm phases such as monosulfate (3CaO·Al2O3·CaSO4·12H2O), and compounds in which the AFt and AFm phases coexist.

[0061] The calcium sulfoaluminate may be either crystalline or amorphous, or may be a mixture of crystalline and amorphous. In calcium sulfoaluminate, a portion of Al2O3 may be substituted with Fe2O3, SiO2, or the like, and a portion of CaSO4 may be substituted with Ca(OH)2, CaCO3, or the like.

[0062] Calcium sulfoaluminate can be produced, for example, by mixing a calcia raw material such as lime, a sulfate raw material such as gypsum, and an alumina raw material such as bauxite so that the molar ratio of CaO:Al2O3:CaSO4 is the desired molar ratio, firing the mixture at a temperature of about 1500°C, and pulverizing it. After firing, silicon dioxide or the like may be added, followed by heat treatment, and then pulverization.

[0063] The Blaine specific surface area of ​​calcium sulfoaluminate is 1000 cm 2 / g~6000cm 2 / g, and 2000 cm 2 / g~4000cm 2 / g is more preferable, and 2200 cm 2 / g~3800cm 2 / g is more preferred. The Blaine specific surface area value is a value measured in accordance with the specific surface area test described in JIS R5201:2015 "Physical testing methods for cement."

[0064] [water] There are no restrictions on the type of water, and tap water, well water, etc. can be used. The water content of the hydraulic composition may be selected depending on the desired fluidity and the desired properties of the hydraulically set product.

[0065] [aggregate] Examples of fine aggregate include river sand, mountain sand, land sand, sea sand, silica sand, crushed sand, crushed lime sand, blast furnace slag fine aggregate, and recycled fine aggregate. The type and content of the fine aggregate can be selected depending on the target mechanical strength of the hydraulic hardened body.

[0066] Examples of coarse aggregate include crushed stone such as andesite, rhyolite, hard sandstone, and limestone, as well as river gravel, mountain gravel, land gravel, blast furnace slag coarse aggregate, and recycled coarse aggregate. The rock type, size, and content of the coarse aggregate can be selected depending on the target mechanical strength of the hydraulic hardened body.

[0067] [Admixture] Examples of admixtures include air-entraining agents, water-reducing agents, air-entraining water-reducing agents, high-performance water-reducing agents, superplasticizers, hardening accelerators, shrinkage-reducing agents, antifoaming agents, water-retaining agents, thickeners, dust-reducing agents, antifreeze and cold-resistant agents, preservatives, waterproofing agents, and rust inhibitors. Admixtures may be used alone or in combination of two or more.

[0068] An example of a high-range water-reducing agent is the following vinyl copolymer (C). Vinyl copolymer (C) is a preferred admixture from the viewpoint of maintaining the fluidity of the hydraulic composition for a long period of time without affecting the hardening property of the hydraulic composition.

[0069] Vinyl copolymer (C): A vinyl copolymer having a structural unit (1) derived from a monomer (1) represented by the following formula (1) and a structural unit (2) derived from at least one monomer (2) selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, and salts thereof, wherein the mass ratio of the structural unit (1) to the structural unit (2) is 75:25 to 95:5 and the mass average molecular weight is 5,000 to 200,000.

[0070] [ka]

[0071] In formula (1), R 1 is an alkenyl group having 2 to 5 carbon atoms or an unsaturated acyl group having 3 to 4 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and A 1 O is an oxyalkylene group having 2 to 4 carbon atoms, m is an integer of 20 to 300, and m A 1 O may be the same or different from each other.

[0072] The vinyl copolymer (C) has a structural unit (1) having a long-chain oxyalkylene group in its side chain and a structural unit (2) having a carboxy group. The structural unit (1) exerts an excluded volume effect due to the steric hindrance of the long-chain oxyalkylene group. The carboxy group of the structural unit (2) adsorbs to cement particles and ground granulated blast furnace slag particles, exerting electrostatic repulsion between these particles. These effects improve the fluidity of hydraulic compositions containing the vinyl copolymer (C). The vinyl copolymer (C) has a mass ratio of the structural unit (1) to the structural unit (2) of structural unit (1):structural unit (2)=75:25 to 95:5, and therefore maintains the fluidity of the hydraulic composition for a long period of time without affecting the curing properties of the hydraulic composition.

[0073] In formula (1), R 1 is an alkenyl group having 2 to 5 carbon atoms or an unsaturated acyl group having 3 to 4 carbon atoms, and is preferably an alkenyl group having 3 to 5 carbon atoms or an unsaturated acyl group having 4 carbon atoms.

[0074] In formula (1), R 2 is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0075] In formula (1), A 1 O is an oxyalkylene group having 2 to 4 carbon atoms, preferably an oxyethylene group or an oxypropylene group, more preferably an oxyethylene group.

[0076] In formula (1), m is an integer of 20 to 300, preferably an integer of 30 to 300, more preferably an integer of 30 to 200, and even more preferably an integer of 30 to 150.

[0077] Examples of the monomer (1) include the following compounds: α-Allyl-ω-methoxy-polyoxyethylene, α-allyl-ω-methoxy-(poly)oxyethylene(poly)oxypropylene, α-allyl-ω-butoxy-polyoxyethylene, α-allyl-ω-butoxy-(poly)oxyethylene(poly)oxypropylene, α-allyl-ω-hydroxy-polyoxyethylene, α-allyl-ω-hydroxy-(poly)oxyethylene(poly)oxypropylene, α-vinyl-ω-methoxy-polyoxyethylene, α-vinyl-ω-methoxy-(poly)oxyethylene(poly) Oxypropylene, α-vinyl-ω-hydroxy-polyoxyethylene, α-vinyl-ω-hydroxy-(poly)oxyethylene (poly)oxypropylene, α-vinyl-ω-hydroxy-(poly)oxybutylene (poly)oxyethylene, α-methallyl-ω-methoxy-polyoxyethylene, α-methallyl-ω-methoxy-(poly)oxyethylene (poly)oxypropylene, α-methallyl-ω-hydroxy-polyoxyethylene, α-methallyl-ω-hydroxy-(poly)oxyethylene (poly)oxypropylene , α-(3-methyl-3-butenyl)-ω-methoxy-polyoxyethylene, α-(3-methyl-3-butenyl)-ω-methoxy-(poly)oxyethylene(poly)oxypropylene, α-(3-methyl-3-butenyl)-ω-hydroxy-polyoxyethylene, α-(3-methyl-3-butenyl)-ω-hydroxy-(poly)oxyethylene(poly)oxypropylene, α-acryloyl-ω-methoxy-polyoxyethylene, α-acryloyl-ω-methoxy-(poly)oxyethylene(poly)oxypropylene, α-Acryloyl-ω-hydroxy-polyoxyethylene, α-acryloyl-ω-hydroxy-polyoxypropylene, α-acryloyl-ω-hydroxy-(poly)oxyethylene(poly)oxypropylene, α-methacryloyl-ω-methoxy-polyoxyethylene, α-methacryloyl-ω-methoxy-(poly)oxyethylene(poly)oxypropylene, α-methacryloyl-ω-hydroxy-polyoxyethylene, α-methacryloyl-ω-hydroxy-(poly)oxyethylene(poly)oxypropylene.

[0078] The structural unit (2) is derived from at least one monomer (2) selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, and salts thereof. When the monomer (2) is a salt, examples thereof include inorganic salts such as sodium salt, potassium salt, calcium salt, and magnesium salt, and organic salts such as diethanolamine salt, triethanolamine salt, and triisopropanolamine salt.

[0079] As the monomer (2), from the viewpoint of achieving a balance between the development of compressive strength that allows the hydraulic composition to be demolded in a short time and the fluidity of the hydraulic composition, at least one selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride and salts thereof is preferred, and at least one selected from acrylic acid, methacrylic acid and salts thereof is more preferred.

[0080] The vinyl copolymer (C) has a mass ratio of the structural unit (1) to the structural unit (2), i.e., structural unit (1):structural unit (2), of 75:25 to 95:5, more preferably 80:20 to 95:5, and even more preferably 82:18 to 93:7. When the mass ratio of the structural units is within the above range, the vinyl copolymer (C) maintains the fluidity of the hydraulic composition for a long period of time without affecting the curing properties of the hydraulic composition.

[0081] The vinyl copolymer (C) may contain structural units other than the structural units (1) and (2). Examples of such structural units include structural units derived from (meth)allylsulfonic acid and salts thereof, (meth)acrylamide, acrylonitrile, (meth)acrylic acid alkyl esters, and (meth)acrylic acid hydroxy esters. When the vinyl copolymer (C) contains other structural units, the proportion of the other structural units in the vinyl copolymer (C) is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0082] The total proportion of the structural units (1) and (2) in the vinyl copolymer (C) is preferably 90% by mass or more, more preferably 93% by mass or more, and even more preferably 95% by mass or more. The vinyl copolymer (C) may be a vinyl copolymer consisting only of the structural units (1) and (2), containing no other structural units than the structural units (1) and (2). In other words, the total proportion of the structural units (1) and (2) in the vinyl copolymer (C) may be 100% by mass.

[0083] The vinyl copolymer (C) has a mass average molecular weight of 5,000 to 200,000, preferably 6,000 to 150,000, more preferably 8,000 to 100,000, and even more preferably 10,000 to 60,000. The mass average molecular weight of the vinyl copolymer (C) is a molecular weight measured by gel permeation chromatography and calculated as PEG / PEO.

[0084] The amount of the vinyl copolymer (C) used is, for example, 0.05 to 1.0 part by mass, and preferably 0.15 to 0.5 part by mass, per 100 parts by mass of the total amount of the binder (A) and the admixture (B).

[0085] [Reinforcement material] The hydraulic composition may contain a reinforcing material. Examples of the reinforcing material include metal fiber, carbon fiber, glass fiber, and basalt fiber. One type of reinforcing material may be used alone, or two or more types may be used in combination.

[0086] [Organic fiber] The hydraulic composition may contain organic fibers to impart explosive resistance to the hydraulically set body. Examples of organic fibers include polypropylene fibers, polyvinyl alcohol fibers, polyvinylidene fibers, polyethylene fibers, polyester fibers, and polylactic acid fibers. One type of organic fiber may be used alone, or two or more types may be used in combination.

[0087] <Method for producing hydraulic composition> The hydraulic composition can be obtained by mixing the above-mentioned materials. The mixing of the materials can be carried out by kneading using a mixer, for example.

[0088] The order of mixing materials when producing a hydraulic composition is not limited. For example, first mix the binder, admixture, and fine aggregate, then add water and admixtures and knead, and then add coarse aggregate and knead. When mixing the binder, admixture, and fine aggregate, reinforcing material and / or organic fiber may be added and kneaded as needed.

[0089] The binder (A) may be a premixed product, or may be mixed with components such as high-early-strength Portland cement and ground granulated blast furnace slag during the production of the hydraulic composition. The binder (B) may be a premixed product, or components such as organic calcium salts, inorganic calcium compounds and inorganic sulfates may be mixed during the production of the hydraulic composition.

[0090] <Hydraulic hardened body> The hydraulically set body of the present disclosure is a cured product of the hydraulic composition of the present disclosure. The hydraulically cured product of the present disclosure is preferably produced by the above-mentioned method for producing a hydraulically cured product, from the viewpoint of developing compressive strength that allows demolding in a short period of time.

[0091] The hydraulic composition of the present disclosure can be cured to form a hydraulically cured body by a method other than the above-described method for producing a hydraulically cured body. In this case, the curing method, curing temperature, and curing time for curing the hydraulic composition are not limited. Room temperature curing, heat curing, steam curing, autoclave curing, underwater curing, air curing, sealed curing, or a combination thereof may be used. [Example]

[0092] The method for producing a hydraulically set body, the hydraulically set body, and the hydraulic composition of the present disclosure will be specifically described below with reference to examples. The method for producing a hydraulically set body, the hydraulically set body, and the hydraulic composition of the present disclosure are not limited to the following examples.

[0093] In the following experiments, Joule heating curing refers to electrical curing in which electricity is passed through the hydraulic composition or hydraulic hardened body during curing, heating it with Joule heat. This curing is performed with the aim of giving the test specimen a temperature history that simulates the internal temperature of the actual component during its manufacture. The Joule heating curing device and method used in the following experiments conformed to the device and method described in JP 2017-20988 A (Concrete strength estimation method and curing device, Takenaka Corporation).

[0094] <Experiment 1> The materials of the mortar specimens are shown in Table 1. Mortar was prepared using the materials shown in Table 1, with a water / binder ratio of 35% and a mass ratio of binder (total of HPC, EA, and HA) to fine aggregate of 1:1.5. The fine aggregate, binder, and admixture were added to a mortar mixer and dry mixed, then water and admixture were added, mixed, scraped off, and mixed again. After mixing, the mixture was filled into a formwork measuring 4 cm x 4 cm x 16 cm and steam cured.

[0095] Steam curing began with heat curing approximately 30 minutes after water was poured in. The temperature history was as follows: specimen temperature 20°C at the start → temperature increased to 25°C at a rate of 0.1°C / min → temperature increased to 75°C at a rate of 0.4°C / min → specimen temperature maintained at 75°C. In this case, it took approximately 2.9 hours after heating began for the specimen temperature to reach 75°C. After the specimen temperature reached 75°C, it was kept at that temperature for 2 hours.

[0096] Strength measurements were carried out three hours after the start of steam curing. The compressive strength of the mortar specimens was measured in accordance with the method specified in JIS R5201:2015 "Physical Testing Methods for Cement." The measurement results are shown in Table 2.

[0097] [Table 1]

[0098] [Table 2]

[0099] An admixture (symbol HA) was prepared for each specimen. The following components were used alone or in combination to prepare an admixture containing organic calcium salts, inorganic calcium compounds, and inorganic sulfates. The amount of CaO, SO3, total alkali, and loss on ignition were adjusted by the combination and mixing ratio of the components. Organic calcium salts: calcium formate, calcium acetate, calcium lactate Inorganic calcium compounds: calcium sulfate, calcium hydroxide, calcium carbonate, calcium oxide Inorganic sulfates: sodium sulfate anhydrous, aluminum sulfate anhydrous, potassium alum Other ingredients: Calcium sulfoaluminate

[0100] The density of the admixture (symbol HA) shown in Table 1 is the density of the admixture used in specimen 1-2. The densities of the admixtures used in the other specimens are also close to this value.

[0101] The admixture used in the test specimens 1-2 to 1-4 is the admixture (B) in this embodiment. The admixtures used in the test specimens 1-5 to 1-8 are admixtures that are different from the chemical composition of the admixture (B). All specimens 1-2 to 1-4 had a compressive strength of 14 N / mm after 3 hours of steam curing. 2 This was higher than that of specimens 1-5 to 1-8.

[0102] <Preparation of admixture (B)> A material equivalent to the admixture used for specimen 1-2 in Experiment 1 was prepared as admixture (B) for use in the following experiments. This admixture is referred to as admixture (B-1). The amount of CaO, SO3, total alkali content, and ignition loss of admixture (B-1) were adjusted by the combination and mixing ratio of the components described above, in the same way as in the preparation of the admixture in Experiment 1. The amount of CaO, SO3, total alkali content, and ignition loss of admixture (B-1) are as follows:

[0103] ·Admixture (B-1) CaO amount: 56% by mass SO3 amount: 17.8% by mass Total alkali content: 2.60% by mass Ignition loss: 22.5% by mass

[0104] <Experiment 2> The materials of the concrete specimens are shown in Table 3, and the mix proportions are shown in Tables 4 and 5. Admixture (B-1) was used as admixture (B).

[0105] Fine aggregate, binder, and admixture were charged into a forced twin-shaft mixer and dry-mixed, then water and admixture were added and mixed, scraped off, and then coarse aggregate was charged and mixed. After mixing, the mixture was poured into a cylindrical formwork measuring 100 mm in diameter x 200 mm, and subjected to Joule heating curing or standard curing.

[0106] In the case of Joule heat curing, heat curing began approximately 30 minutes after pouring water. The temperature history for Joule heat curing was as follows: specimen temperature 20°C at the start → temperature increased at a constant rate to 30°C after 1 hour → temperature increased at a constant rate to 75°C after 3 hours → specimen temperature maintained at 75°C.

[0107] A slump test was conducted in accordance with JIS A1101:2020 "Concrete slump test method." The measurement results are shown in Table 5.

[0108] Compressive strength (N / mm2) according to JIS A1108:2018 "Concrete compressive strength test method" 2 The measurement results are shown in Table 6 and Figure 1.

[0109] [Table 3]

[0110] [Table 4]

[0111] [Table 5]

[0112] [Table 6]

[0113] Data on the compressive strength of Joule heat cured specimens 2-6 and 2-7 could not be obtained due to equipment malfunction.

[0114] The compressive strengths shown in Table 6 are shown as a bar graph in Figure 1. The bars in Figure 1, from left to right, represent the compressive strength after Joule heating curing for 3 hours, 3.5 hours, and 4.5 hours, and after standard curing for 1 day, 7 days, and 28 days.

[0115] In order to lift and remove a specimen of this shape and size, the compressive strength must be 6N / mm 2 It is desirable that this is the case. In the case of specimens with a water-binder ratio of 30%, specimens 2-2 and 2-3, which were mixed with admixture (B), achieved a compressive strength of 6 N / mm after 3 hours of Joule heating curing. 2 On the other hand, specimen 2-1, which was not mixed with admixture (B), had a compressive strength of 6 N / mm after 3 hours of Joule heating curing. 2 It fell far short of the target. In the case of specimens with a water-binder ratio of 40%, specimen 2-5, which was mixed with admixture (B), achieved a compressive strength of 6 N / mm after 3.5 hours of Joule heating curing. 2 On the other hand, specimen 2-4, which was not mixed with admixture (B), had a compressive strength of 6 N / mm after 3.5 hours of Joule heating curing. 2 did not reach. In the case of specimens with a water-binder ratio of 50%, specimens 2-8 and 2-9 mixed with admixture (B) achieved a compressive strength of 6 N / mm after 3.5 hours of Joule heating curing. 2 The compressive strength reached approximately 6N / mm after 4.5 hours of Joule heating curing. 2 significantly exceeded.

[0116] Comparing specimens 2-5 and 2-10, which have the same water-binder ratio and admixture (B) content but different amounts of ground granulated blast furnace slag, the compressive strength of specimen 2-5, which had a higher amount of ground granulated blast furnace slag after 3.5 hours of Joule heating curing, was higher. In other words, the development of strength in the very early stages tended to be faster when the amount of ground granulated blast furnace slag was higher.

[0117] <Experiment 3> The materials of the concrete specimens are shown in Table 7, and the mix proportions are shown in Tables 8 and 9. Admixture (B-1) was used as admixture (B).

[0118] Fine aggregate, binder, and admixture were charged into a forced twin-shaft mixer and dry-mixed, then water and admixture were added and mixed, scraped off, and then coarse aggregate was charged and mixed. After mixing, the mixture was poured into formwork for thick members (1000mm x 1000mm x 1000mm), formwork for thin members (900mm x 900mm x 220mm), and formwork for mock test specimens (cylindrical formwork with a diameter of 100mm x 200mm), and then cured.

[0119] The thick and thin members were steam cured. The temperature history of the steam curing is shown in Figure 2. The thick members were steam cured in one stage, with the temperature reached at 90°C. The thin members were steam cured in two stages, with the temperature reached at 45°C in the first stage and 75°C in the second stage.

[0120] The simulated test specimens were subjected to the following Joule heating curing, steam curing in the same manner as the thin members, or standard curing. Joule heating curing: A mock test specimen with a thermocouple installed in the center and a thin material with a thermocouple installed in the center were prepared, and the temperature history of the Joule heating curing was adjusted so that the temperature at the center of the mock test specimen would follow the temperature at the center of the thin material during steam curing.

[0121] A slump test was conducted in accordance with JIS A1101:2020 "Concrete slump test method." The measurement results are shown in Table 9.

[0122] Compressive strength (N / mm2) according to JIS A1108:2018 "Concrete compressive strength test method" 2 The measurement results are shown in Table 10 and Figure 3.

[0123] [Table 7]

[0124] [Table 8]

[0125] [Table 9]

[0126] [Table 10]

[0127] The compressive strengths of the simulated test specimens, which are listed in Table 10, are shown as a bar graph in Figure 3. The bars in Figure 3, from left to right, represent the compressive strengths after Joule heating curing for 3 hours, 3.5 hours, 4.5 hours, and 5.5 hours, steam curing for 3.5 hours and 1 day, and standard curing for 1 day and 7 days.

[0128] In order to lift and remove a simulated specimen of this shape and size, the compressive strength must be 6N / mm 2 It is desirable that this is the case. The simulated specimens 3-1 to 3-3 took longer to develop strength as the water-binder ratio increased, but they reached a compressive strength of 6 N / mm within 4.5 hours of Joule heating curing. 2 exceeded. All of the simulated specimens 3-1 to 3-3 had a compressive strength of 6 N / mm after 3.5 hours of steam curing. 2 significantly exceeded.

Claims

1. a step of kneading a hydraulic composition containing the following binder (A), the following admixture (B), water, aggregate, and admixture, wherein the proportion of the following admixture (B) in the total of the following binder (A) and the following admixture (B) is 2% by mass to 10% by mass; A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of 30 cm to 150 cm among width, length, and height; and a curing step of steam curing the hydraulic composition cast into the formwork at a temperature of 50°C to 95°C for 2.0 hours to 5.0 hours. A method for producing a hydraulic cured body. Binder (A): A binder containing high-early-strength Portland cement and ground granulated blast furnace slag, wherein the proportion of the high-early-strength Portland cement is 20% by mass to 55% by mass, the proportion of the ground granulated blast furnace slag is 45% by mass to 75% by mass, and the total of the high-early-strength Portland cement and the ground granulated blast furnace slag accounts for 90% by mass or more of the total. Admixture (B): Contains organic calcium salt, inorganic calcium compound, and inorganic sulfate, and has a CaO content of 53% to 58% by mass. ３ % by weight, a total alkali content of 2.5% by weight to 2.8% by weight, and a loss on ignition of 20% by weight to 25% by weight.

2. a step of kneading a hydraulic composition containing the following binder (A), the following admixture (B), water, aggregate, and admixture, wherein the proportion of the following admixture (B) in the total of the following binder (A) and the following admixture (B) is 2% by mass to 10% by mass; A step of pouring the kneaded hydraulic composition into a formwork having a minimum dimension of width, length, and height of less than 30 cm; a first curing step of steam curing the hydraulic composition cast into the formwork at a temperature of 30°C to 48°C for 0.6 hours to 1.5 hours; a second curing step of steam curing the hydraulic composition that has been subjected to the first curing step at a temperature of 60°C to 85°C for 0.8 hours to 2.0 hours; A method for producing a hydraulic cured body. Binder (A): A binder containing high-early-strength Portland cement and ground granulated blast furnace slag, wherein the proportion of the high-early-strength Portland cement is 20% by mass to 55% by mass, the proportion of the ground granulated blast furnace slag is 45% by mass to 75% by mass, and the total of the high-early-strength Portland cement and the ground granulated blast furnace slag accounts for 90% by mass or more of the total. Admixture (B): Contains organic calcium salt, inorganic calcium compound, and inorganic sulfate, and has a CaO content of 53% to 58% by mass. ３ % by weight, a total alkali content of 2.5% by weight to 2.8% by weight, and a loss on ignition of 20% by weight to 25% by weight.

3. The binder (A) contains a sulfate, and the ratio of the sulfate in the binder (A) is SO ３ The method for producing a hydraulically hardened body according to claim 1 or claim 2, wherein the amount of the water-soluble polymer is 1% by mass to 5% by mass in terms of the total mass of the water-soluble polymer.

4. 3. The method for producing a hydraulically hardened body according to claim 1, wherein the admixture comprises the following vinyl copolymer (C): Vinyl copolymer (C): A vinyl copolymer having a structural unit (1) derived from a monomer (1) represented by the following formula (1) and a structural unit (2) derived from at least one monomer (2) selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, and salts thereof, wherein the mass ratio of the structural unit (1) to the structural unit (2) is 75:25 to 95:5 and the mass average molecular weight is 5,000 to 200,000. 【Chemistry 1】 In formula (1), R １ is an alkenyl group having 2 to 5 carbon atoms or an unsaturated acyl group having 3 to 4 carbon atoms, and R ２ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and A １ O is an oxyalkylene group having 2 to 4 carbon atoms, m is an integer of 20 to 300, and m A １ The O's may be the same or different.

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