Hydraulic composition, method for producing hydraulic composition, method for producing hardened product, and method for suppressing fluctuations in compressive strength

Abstract

To provide a hydraulic composition which suppresses variations in compressive strength exhibited by curing even when a blending amount of cement clinker varies, in a region where the blending amount of the cement clinker is 5 mass% or less.SOLUTION: A hydraulic composition contains cement composed of an alkali stimulant, a granulated blast furnace slag and gypsum, and an accelerator, wherein with respect to 100 mass% of the total of the alkali stimulant and the granulated blast furnace slag, a content of the alkali stimulant is 0.1-5.0 mass%, a content of the granulated blast furnace slag is 95.0-99.9 mass%, a content of the gypsum in the cement is 2.5-10.0 mass% in terms of SO3, and with respect to 100 pts.mass of the cement, a content of the accelerator is 0.2-12.0 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a hydraulic composition, a method for producing a hydraulic composition, a method for producing a hardened body, and a method for suppressing fluctuations in compressive strength. [Background technology]

[0002] In recent years, with the increasing demand for measures to combat global warming, there has been a demand for a reduction in CO2 emissions during cement production. One method that has been widely studied to reduce CO2 emissions is to produce cement by replacing part of the cement clinker, which generates a large amount of CO2 during preparation, with admixtures. Among these admixtures, steel slag, such as blast furnace slag, is expected to improve the long-term strength of concrete and its salt-blocking effect. Therefore, research is being conducted into cement that uses steel slag as an admixture and increases its mixing ratio.

[0003] Blast-furnace cement, in which part of the cement clinker has been replaced with blast-furnace slag such as granulated blast-furnace slag (BFS), is classified according to the percentage of replacement. JIS R 5211:2019 specifies Type B blast-furnace cement, which contains more than 30% but not more than 60% blast-furnace slag by mass, and Type C blast-furnace cement, which contains more than 60% but not more than 70% by mass, but there are currently no specifications for cement with a blast-furnace slag content of more than 70% by mass.

[0004] From the viewpoint of reducing the amount of CO2 generated, research is also being conducted on cement compositions containing an even higher amount of blast furnace slag than that of blast furnace cement type C (for example, Non-Patent Document 1). Non-Patent Document 1 confirms that the cement composition hardens when the amount of cement clinker mixed is 1 mass %. However, this amount needs to be strictly controlled. For example, the example described in Non-Patent Document 1 shows that when the amount of cement clinker mixed is 4 to 5 mass %, the hardening reaction of the cement composition does not proceed and the compressive strength drops drastically. Specifically, when the amount of cement clinker mixed is 1 mass %, the hardening reaction of the cement composition does not progress and the compressive strength drops drastically. 2The strength of the concrete varies from 1% by mass to 10N / mm 2 It has been observed that a large range of fluctuations can occur, with the intensity decreasing to less than 1000 kJ / s.

[0005] Generally, the accuracy of measurements in preparing cement compositions at an industrial level is said to be at most 1 to 2% by mass, and as mentioned above, it is not realistic to control the amount of cement clinker to 1% by mass, making it difficult to commercialize cement compositions with extremely high amounts of blast furnace slag. From this perspective, it is common knowledge in the industry that, in practice, it is appropriate to adjust the amount of cement clinker to 30% by mass or more, as specified in JIS. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Tokyo Institute of Technology et al., "ECM Cement: A Low-Carbon Cement That Can Reduce Energy Consumption and CO2 Emissions by More Than 60%," Figure 6, [online], May 2017, NEDO Practical Application Document, [Retrieved January 4, 2022], Internet<URL:https: / / www.nedo.go.jp / hyoukabu / articles / 201705ecm / index.html> Summary of the Invention [Problem to be solved by the invention]

[0007] It would be useful to have a technology that can prevent the compressive strength of a hydraulic composition when set from fluctuating significantly from the expected value or falling below the expected value due to a slight difference in the amount of cement clinker in a range where the amount of cement clinker is extremely low (for example, a range of 5 mass % or less), and that can produce a hydraulic composition that can exhibit stable quality even with industrial-level measuring accuracy.

[0008] The present disclosure aims to provide a hydraulic composition in which fluctuations in compressive strength exhibited by hardening are suppressed even when the amount of cement clinker varies in a range where the amount of cement clinker is 5% by mass or less, and a method for producing the same.The present disclosure also aims to provide a method for producing a hardened body using the hydraulic composition.The present disclosure also aims to provide a method for suppressing fluctuations in compressive strength even when the amount of cement clinker varies. [Means for solving the problem]

[0009] One aspect of the present disclosure provides a hydraulic composition comprising cement made of an alkaline activator, granulated blast furnace slag, and gypsum, and an accelerator, wherein, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag, the content of the alkaline activator is 0.1 to 5.0 mass%, the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, the content of the gypsum in the cement is 2.5 to 10.0 mass% in terms of SO3, and the content of the accelerator is 0.2 to 12.0 parts by mass relative to 100 parts by mass of the cement.

[0010] The hydraulic composition is adjusted so that the gypsum content in the cement and the accelerator content in the hydraulic composition are within a predetermined range. This allows compositions with a low amount of alkaline activator, such as cement clinker, to harden and exhibit sufficient compressive strength. Furthermore, even when the amount of alkaline activator varies within a range of 0.1 to 5.0 mass% due to the measurement during preparation of the hydraulic composition, extreme fluctuations in compressive strength, as observed in conventional hydraulic compositions, are suppressed. The reason for this effect is unclear. However, since the addition of an accelerator accelerates the hardening reaction of the hydraulic composition, it is generally believed that the addition of an accelerator makes the reaction more difficult to control and results in greater fluctuations in compressive strength than when the reaction proceeds more slowly. In light of this common technical knowledge of those skilled in the art, the fact that the above-mentioned effects can be achieved by adjusting the amounts of gypsum and accelerator is a new finding that would have been difficult to predict.

[0011] The accelerator may contain at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts. By containing the accelerator, the reactivity of the granulated blast furnace slag can be further improved.

[0012] The accelerator may contain a salt having a monovalent anion. By containing a salt having a monovalent anion in the accelerator, the influence of differences in the content of the alkaline activator can be further reduced.

[0013] The accelerator may contain a calcium salt, which can further reduce the influence of differences in the content of the alkaline activator.

[0014] The accelerator may contain at least one selected from the group consisting of nitrites, nitrates, and chlorides.

[0015] The alkali activator may contain at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime. When the alkali activator contains the above-mentioned component, the hydration reaction of the granulated blast furnace slag can be accelerated, and the hardening reaction in the hydraulic composition can be further accelerated.

[0016] The gypsum may contain at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate. When the gypsum contains at least one of gypsum dihydrate and gypsum hemihydrate, the initial reaction between the alkaline activator (e.g., Portland cement clinker) and the granulated blast furnace slag can be further promoted.

[0017] The basicity of the granulated blast furnace slag may be 1.60 to 1.95.

[0018] The aluminum oxide content in the granulated blast furnace slag may be 10.0% by mass or more.

[0019] The content of the alkaline activator may be 0.2 to 3.5 mass%, and the content of the granulated blast furnace slag may be 96.5 to 99.8 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag.

[0020] One aspect of the present disclosure provides a method for producing a hydraulic composition, including: a first step of mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum to prepare cement; and a second step of mixing 0.2 to 12.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement, wherein the first step includes adjusting the amount of the alkaline activator to 0.1 to 5.0% by mass and the amount of the granulated blast furnace slag to 95.0 to 99.9% by mass, based on a total of 100% by mass of the alkaline activator and the granulated blast furnace slag, and adjusting the content of gypsum in the cement to 2.5 to 10.0% by mass in terms of SO3.

[0021] In the above production method, the content of gypsum in the cement is adjusted in the first step, and the content of the accelerator is adjusted in the second step, thereby making it possible to produce the hydraulic composition as described above.

[0022] One aspect of the present disclosure provides a method for producing a hardened body, the method comprising: a first step of mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum to prepare cement; a second step of mixing 0.2 to 12.0 parts by mass of an accelerator with 100 parts by mass of the cement to obtain a hydraulic composition; and a third step of mixing 50 parts by mass of water with 100 parts by mass of the hydraulic composition, the first step comprising adjusting the amount of the alkaline activator to 0.1 to 5.0% by mass and the amount of the granulated blast furnace slag to 95.0 to 99.9% by mass, based on a total of 100% by mass of the alkaline activator and the granulated blast furnace slag, and adjusting the content of gypsum in the cement to 2.5 to 10.0% by mass, calculated as SO3.

[0023] In the method for producing the hardened product, the content of gypsum in the cement is adjusted in the first step, and the content of the accelerator is adjusted in the second step, thereby making it possible to prepare the hydraulic composition described above, and by mixing this with water, it is possible to produce mortar that can exhibit excellent compressive strength.

[0024] One aspect of the present disclosure provides a method for suppressing fluctuations in compressive strength, comprising adjusting the content of gypsum in a composition containing cement made from an alkaline activator, granulated blast furnace slag, and gypsum to 2.5 to 10.0 mass% in terms of SO3 relative to the total amount of the cement, and adjusting the content of an accelerator to 0.2 to 12.0 parts by mass relative to 100 parts by mass of the cement, wherein the content of the alkaline activator in the composition is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag.

[0025] The method for suppressing the above-mentioned fluctuations in compressive strength is to adjust the contents of gypsum and accelerator to fall within a predetermined range for a so-called low-cement hydraulic composition containing a small amount of alkaline activator, thereby suppressing large changes in compressive strength that may occur when the hydraulic composition is hardened due to differences in the amount of alkaline activator. [Effects of the Invention]

[0026] According to the present disclosure, it is possible to provide a hydraulic composition in which fluctuations in compressive strength exhibited by hardening are suppressed even when the amount of cement clinker varies in a range where the amount of cement clinker is 5% by mass or less, and a method for producing the same. According to the present disclosure, it is also possible to provide a method for producing a hardened body using the above-mentioned hydraulic composition. According to the present disclosure, it is also possible to provide a method for suppressing fluctuations in compressive strength even when the amount of cement clinker varies. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present disclosure will be described. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content. In the following description, when it is written "X to Y" (X and Y are arbitrary numbers), it means "X or more and Y or less" unless otherwise specified.

[0028] Unless otherwise specified, the materials exemplified in this specification can be used singly or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0029] [Hydraulic composition] One embodiment of the hydraulic composition includes cement containing an alkaline activator, granulated blast furnace slag, and gypsum, and an accelerator. In the hydraulic composition, the content of the alkaline activator is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on 100 mass% of the total of the alkaline activator and the granulated blast furnace slag. The content of the gypsum in the cement is 2.5 to 10.0 mass% calculated as SO3. The content of the accelerator is 0.2 to 12.0 mass parts per 100 mass parts of the cement.

[0030] In this specification, cement refers not only to cases where the alkaline stimulant contains cement clinker, but also to a powder containing granulated blast furnace slag as the main component and containing an alkaline stimulant (in some cases, a powder further containing gypsum).

[0031] The alkali activator is a component that stimulates the hardening reaction of the granulated blast furnace slag and promotes the hardening reaction of the hydraulic composition. The alkali activator may contain, for example, at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime, or may be any one of Portland cement clinker, slaked lime, and quicklime, or may be Portland cement clinker.

[0032] Portland cement clinker can use Portland cement clinker used for preparing various Portland cements specified in JIS R 5210:2003 "Portland Cement". Examples of the various Portland cements include ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, and low heat Portland cement. The Portland cement clinker may be a Portland cement clinker used for preparing ordinary Portland cement and early-strength Portland cement.

[0033] The mineral composition of Portland cement clinker can be calculated by the Bogue formula. Here, the Bogue formula is a formula widely used to calculate the content rate of main minerals in Portland cement clinker from the content ratio of chemical composition. By using the Bogue formula shown below, the content of tricalcium silicate (3CaO·SiO2, denoted as C3S), dicalcium silicate (2CaO·SiO2, denoted as C2S), and tricalcium aluminate (3CaO·Al2O3, denoted as C3A) in Portland cement clinker can be calculated. In the following formula, "%" means "mass%". The chemical formula represents the content ratio (mass%) of each compound shown by the chemical analysis value according to JIS R 5204:2019 "Fluorescent X-ray Analysis Method for Cement".

[0034] <Bogue formula> C3S [%]=(4.07×CaO [%])-(7.60×SiO2 [%])-(6.72×Al2O3 [%])-(1.43×Fe2O3 [%])-(2.85×SO3 [%]) C2S [%]=(2.87×SiO2 [%])-(0.754×C3S [%]) C3A [%]=(2.65×Al2O3 [%])-(1.69×Fe2O3 [%]) C4AF [%]=3.04×Fe2O3 [%]

[0035] The C3A content in the Portland cement clinker may be preferably 0.5 to 11.0 mass%, more preferably 0.5 to 10.5 mass%, even more preferably 0.5 to 10.0 mass%, and particularly preferably 0.5 to 9.5 mass%. When the C3A content in the Portland cement clinker is within the above range, it is possible to further reduce the amount of gypsum that inhibits the hydration reaction in the hydraulic composition, and also to more fully exhibit the hydration reaction of granulated blast furnace slag.

[0036] The fineness of the Portland cement clinker may be adjusted from the viewpoint of further improving the performance of the hydration reaction in the hydraulic composition. The lower limit of the Blaine specific surface area of ​​the Portland cement clinker is, for example, 2800 cm 2 / g or more, or 3000cm 2 / g or more. By setting the lower limit of the Blaine specific surface area of ​​the Portland cement clinker within the above range, the hydration reaction with the granulated blast furnace slag can be further promoted. The upper limit of the Blaine specific surface area of ​​the Portland cement clinker can be set to, for example, 10,000 cm 2 / g or less, 5000cm 2 / g or less, 4000cm 2 / g or less, or 3500cm 2 / g or less. By setting the upper limit of the Blaine specific surface area of ​​the Portland cement clinker within the above range, it is possible to reduce the production cost of the hydraulic composition and further reduce CO2 emissions in the production of the Portland cement clinker. The Blaine specific surface area of ​​the Portland cement clinker may be adjusted within the above range, for example, 2800 to 10000 cm 2 / g, 3000-5000cm 2 / g, 3000-4000cm 2 / g, or 3000-3500cm 2 / g.

[0037] The granulated blast furnace slag may be, for example, commercially available, or slag equivalent to granulated blast furnace slag may be prepared and used.

[0038] The upper limit of the aluminum oxide content (also referred to as the Al2O3 content) in the granulated blast furnace slag may be, for example, 14.5% by mass or less, or 14.3% by mass or less. When the Al2O3 content in the granulated blast furnace slag is within the above range, the long-term strength development of the resulting hydraulic composition can be further prevented from decreasing. The lower limit of the Al2O3 content in the granulated blast furnace slag may be, for example, 10.0% by mass or more, 11.0% by mass or more, 12.0% by mass or more, or 13.0% by mass or more. When the lower limit of the Al2O3 content in the granulated blast furnace slag is within the above range, the latent hydraulic properties of the granulated blast furnace slag can be more fully exhibited. The term "latent hydraulic properties" refers to the property of initiating a hydration reaction by adding an alkaline activator. The amount of Al2O3 in the granulated blast furnace slag may be adjusted within the above range, for example, 10.0 to 14.5 mass%, 12.0 to 14.5 mass%, or 13.0 to 14.5 mass%.

[0039] The lower limit of the silicon dioxide content (also referred to as the SiO2 content) in the granulated blast furnace slag may be, for example, 30.0 mass% or more, 33.0 mass% or more, 34.0 mass% or more, 34.5 mass% or more, or 35.0 mass% or more. By ensuring that the lower limit of the SiO2 content in the granulated blast furnace slag is within the above range, it is possible to suppress a decrease in the initial and long-term strength development. The upper limit of the SiO2 content in the granulated blast furnace slag may be, for example, 40.0 mass% or less, 38.0 mass% or less, 36.5 mass% or less, or 35.5 mass% or less. By ensuring that the upper limit of the SiO2 content in the granulated blast furnace slag is within the above range, it is possible to suppress a decrease in the initial strength development. The SiO2 content of the granulated blast furnace slag may be adjusted within the above range, for example, 33.0 to 40.0 mass% or 34.0 to 35.5 mass%.

[0040] The lower limit of the calcium oxide content (also referred to as the CaO content) in the granulated blast furnace slag may be, for example, 35.0 mass% or more, 38.5 mass% or more, or 40.0 mass% or more. When the lower limit of the CaO content in the granulated blast furnace slag is within the above range, the initial strength development can be further improved. The upper limit of the CaO content in the granulated blast furnace slag may be, for example, 45.0 mass% or less, 43.5 mass% or less, 43.0 mass% or less, 42.5 mass% or less, 42.0 mass% or less, or 41.5 mass% or less. When the upper limit of the CaO content in the granulated blast furnace slag is within the above range, the deterioration of the long-term strength development can be suppressed. The CaO content in the granulated blast furnace slag may be adjusted within the above range, for example, 38.5 to 45.0 mass% or 40.0 to 42.5 mass%.

[0041] The lower limit of the magnesium oxide content (also referred to as MgO content) in the granulated blast furnace slag may be, for example, 4.0% by mass or more, 5.0% by mass or more, 5.5% by mass or more, 6.0% by mass or more, or 7.0% by mass or more. By ensuring that the lower limit of the MgO content in the granulated blast furnace slag is within the above range, it is possible to suppress a decrease in the initial and long-term strength development. The upper limit of the MgO content in the granulated blast furnace slag may be, for example, 10.0% by mass or less, 9.0% by mass or less, less than 7.5% by mass, less than 7.4% by mass, less than 7.2% by mass, or less than 7.1% by mass. By ensuring that the upper limit of the MgO content in the granulated blast furnace slag is within the above range, it is possible to suppress a decrease in the initial strength development. The MgO content in the granulated blast furnace slag may be adjusted within the above range, for example, 4.0 to 10.0% by mass, or 6.0% by mass or more but less than 7.4% by mass.

[0042] Granulated blast furnace slag may contain, as other components, for example, sulfur trioxide (SO3), sodium oxide (NaO2), potassium oxide (K2O), and titanium oxide (TiO2).

[0043] The chemical composition of granulated blast furnace slag in this specification means a value measured in accordance with the description of JIS R 5202:2015 "Methods for chemical analysis of cement."

[0044] The reactivity of granulated blast furnace slag is evaluated by an index called basicity, which is expressed as the value of (CaO + MgO + Al2O3) / SiO2 (the ratio of the total content of calcium oxide, magnesium oxide, and aluminum oxide to the content of silicon dioxide in granulated blast furnace slag). Either high-basicity or low-basicity granulated blast furnace slag can be used.

[0045] Granulated blast furnace slag having a basicity of, for example, 1.60 to 1.95 can be widely used. Granulated blast furnace slag having a basicity of less than 1.75 has a low basicity and is generally considered to be low-grade slag with low reactivity, but can be used as a component of the hydraulic composition of the present disclosure.

[0046] The upper limit of the basicity of the granulated blast furnace slag may be, for example, 1.95 or less, less than 1.95, less than 1.90, less than 1.85, or less than 1.80. The lower limit of the basicity of the granulated blast furnace slag, which has relatively excellent reactivity, may be, for example, more than 1.75 or 1.78 or more. When the lower limit of the basicity is within the above range, it can be easier to improve the early strength of the hydraulic composition. The basicity of the granulated blast furnace slag can be adjusted within the above range, and may be, for example, 1.75 to 1.95, or 1.75 or more but less than 1.80.

[0047] In the hydraulic composition according to the present disclosure, granulated blast furnace slag with low basicity can also be used. Low-basicity granulated blast furnace slag is often avoided as a low-grade slag because it is difficult to obtain sufficient compressive strength. However, in the hydraulic composition according to the present disclosure, the hardening reaction can be sufficiently accelerated by blending a relatively large amount of gypsum and adjusting the content of the accelerator, so even such low-grade slag can be used. The upper basicity limit of such low-grade granulated blast furnace slag may be, for example, less than 1.75, less than 1.70, or less than 1.65. The lower basicity limit of the low-grade granulated blast furnace slag is not particularly limited, but may be, for example, 1.60 or more, or 1.65 or more. The basicity of the low-grade granulated blast furnace slag may be adjusted within the above-mentioned range, for example, 1.60 or more but less than 1.75.

[0048] The basicity in this specification is a value measured in accordance with the description in JIS A 6206:2013 "Ground granulated blast furnace slag for concrete," and specifically means the value of (CaO + MgO + Al2O3) / SiO2 (the ratio of the total content of calcium oxide, magnesium oxide, and aluminum oxide to the content of silicon dioxide).

[0049] The specific surface area of ​​granulated blast furnace slag is, for example, 2500 to 10000 cm 2 / g, 2500-8000cm 2 / g, 2500-6000cm 2 / g, 2500-5000cm 2 / g, 3000-5000cm 2 / g, 4000-5000cm 2 / g, or 4000 to 4500 cm 2 / g.

[0050] In this specification, the term "Blaine specific surface area" refers to a value measured in accordance with the method described in JIS R 5201:2015 "Physical testing methods for cement."

[0051] The hydraulic composition according to the present disclosure is a so-called low-cement hydraulic composition, and the content of the alkaline activator in the cement is relatively small. That is, the content of the alkaline activator and the granulated blast furnace slag is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on 100 mass% of the total of the alkaline activator and the granulated blast furnace slag.

[0052] The contents of the alkaline stimulant and the granulated blast furnace slag are, based on a total of 100 mass% of the alkaline stimulant and the granulated blast furnace slag, for example, the content of the alkaline stimulant may be 0.1 to 4.0 mass% and the content of the granulated blast furnace slag may be 96.0 to 99.9 mass%, the content of the alkaline stimulant may be 0.2 to 3.5 mass% and the content of the granulated blast furnace slag may be 96.5 to 99.8 mass%, the content of the alkaline stimulant may be 0.5 to 3.5 mass% and the content of the granulated blast furnace slag may be 96.5 to 99.5 mass%, or the content of the alkaline stimulant may be 1.0 to 3.5 mass% and the content of the granulated blast furnace slag may be 96.5 to 99.0 mass%. By adjusting the content of the alkaline activator and the granulated blast furnace slag in the hydraulic composition in this manner, the amount of CO2 generated during the production of the hydraulic composition can be suppressed, and the hydraulic composition can also exhibit excellent compressive strength when hardened.

[0053] The content of the alkaline activator in this specification refers to a value determined by the following method. Because the detection methods for the alkaline activators Portland cement clinker, slaked lime, and quicklime are different, the following three measurements are performed and the total amount is calculated to determine the content of the alkaline activator. First, the content of Portland cement clinker among the alkaline activators is determined. Specifically, a hydraulic composition is heated at 900°C for 1 hour to crystallize the granulated blast furnace slag (glass) to prepare a measurement sample. X-ray diffraction measurement is then performed on the measurement sample, and the crystalline phases in the measurement sample are quantified by Rietveld analysis to determine the total amount of alite, belite, aluminate phase, and ferrite phase as the Portland cement clinker content. Next, the content of slaked lime among the alkaline activators is determined. The weight loss of 1 g of the hydraulic composition is measured by thermogravimetric differential thermal analysis (TG-DTA), and the weight loss value around 450 to 500°C is calculated as the amount of HO due to the thermal decomposition reaction. The value obtained by converting the above weight loss value back into slaked lime (Ca(OH)2) using each molecular weight is taken as the slaked lime content. Finally, the quicklime (CaO) content of the alkaline activator is determined as follows: CaO is calculated using the above Rietveld analysis method, and the quicklime content is determined by subtracting the content of slaked lime (Ca(OH)2) calculated by thermogravimetry-differential thermal analysis (TG-DTA) converted to quicklime (CaO) from the calculated value. The contents of Portland cement clinker, slaked lime, and quicklime calculated as above are added together to determine the content of the alkaline activator.

[0054] The content of granulated blast furnace slag in this specification refers to a value determined by the following method. Specifically, a measurement sample is prepared by heating a hydraulic composition at 900°C for 1 hour to crystallize the granulated blast furnace slag (glass). The measurement sample is then subjected to X-ray diffraction measurement, and the crystalline phases in the measurement sample are quantified by Rietveld analysis to quantify gehlenite, akermanite, and merwinite as crystalline phases formed by crystallization of the granulated blast furnace slag, and the total amount of these is defined as the content of granulated blast furnace slag. When a hydraulic composition is manufactured by one's own manufacturing process, the blending amount (measured value) of granulated blast furnace slag added during the manufacturing process corresponds to the above content.

[0055] In the hydraulic composition according to the present disclosure, the gypsum content in the cement is relatively large from the viewpoint of exhibiting excellent compressive strength. The gypsum content in the cement is 2.5 to 10.0 mass% in terms of SO3. By having the gypsum content within this range, even a hydraulic composition with a low content of alkaline activator can exhibit the effect of improving compressive strength as the hydraulic composition hardens due to the gypsum, and even if the content of alkaline activator varies within the above range depending on the conditions of the accelerator, etc., which are prepared in a predetermined amount, extreme fluctuations in compressive strength are suppressed.

[0056] The upper limit of the gypsum content in the cement, calculated as SO3, may be, for example, 9.0% by mass or less, 8.0% by mass or less, 7.5% by mass or less, or 7.0% by mass or less. By setting the upper limit of the gypsum content within the above range, the initial and long-term strength development can be further improved. The lower limit of the gypsum content in the cement, calculated as SO3, may be, for example, 3.0% by mass or more, 3.5% by mass or more, 4.0% by mass or more, 4.5% by mass or more, 5.0% by mass or more, 5.5% by mass or more, 6.0% by mass or more, or 6.5% by mass or more. By setting the lower limit of the gypsum (SO3) content within the above range, the hydration reaction of the cement can be more favorable, the fluidity of the hydraulic composition after mixing with water can be further improved, and the early strength development can be further improved. The gypsum content in the cement may be adjusted within the above range, for example, 3.0 to 8.0% by mass or 6.0 to 7.0% by mass.

[0057] The gypsum content in this specification refers to the total amount of gypsum components that may be contained in the alkaline activator and granulated blast furnace slag, as well as the gypsum components that are blended with the cement. The gypsum content in this specification refers to a value determined by the method described below. Specifically, the gypsum content is measured in accordance with the SO3 analysis method specified in JIS R 5202:2015 "Methods for Chemical Analysis of Cement."

[0058] Examples of gypsum that can be used include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum. The gypsum may contain at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate, or may be one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate. The gypsum may be gypsum obtained by recycling waste gypsum board.

[0059] The Blaine specific surface area of ​​the cement is, for example, 2800 to 10000 cm 2 / g. When the alkali activator constituting the cement contains Portland cement clinker, the Portland cement clinker, granulated blast furnace slag, and gypsum may be simultaneously ground to produce cement. When simultaneously ground, the lower limit of the Blaine specific surface area of ​​the cement is, for example, 2800 cm 2 / g or more, or 3000cm 2 / g or more. By setting the lower limit of the Blaine specific surface area of ​​the cement within the above range, the hydration reaction with the granulated blast furnace slag can be further promoted. The upper limit of the Blaine specific surface area of ​​the cement can be set to, for example, 10,000 cm 2 / g or less, 5000cm 2 / g or less, 4000cm 2 / g or less, or 3500cm 2 / g or less.

[0060] The accelerator is a compound that accelerates the reaction of granulated blast furnace slag and improves its early strength.

[0061] The accelerator may contain at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts. The accelerator containing an alkali metal salt or alkaline earth metal salt can further improve the reactivity of granulated blast furnace slag. Examples of alkali metals include sodium and potassium, and examples of alkaline earth metals include magnesium and calcium. From the viewpoint of promoting hydrate formation and improving compressive strength, the alkaline earth metal preferably contains calcium, and calcium is more preferred. While calcium hydroxide (Ca(OH)2) eluted from cement clinker is thought to contribute to the initiation of the hardening reaction of granulated blast furnace slag, a calcium salt accelerator can be expected to accelerate the hardening of granulated blast furnace slag in the same way as the components eluted from cement clinker. Therefore, a calcium salt accelerator can be expected to sufficiently harden granulated blast furnace slag even in a range where the content of the alkali activator is low. This effect allows for greater tolerance to variations in the amount of alkali activator in the hydraulic composition.

[0062] The accelerator may contain a salt having a monovalent anion, or may contain a calcium salt. The accelerator may contain at least one selected from the group consisting of nitrites, nitrates, and chlorides. When the accelerator contains a nitrite, the early strength of the hydraulic composition during hardening can be further improved. When the accelerator contains a nitrite, the amount of heat generated by hydration during hardening of the hydraulic composition can also be reduced.

[0063] More specific examples of the accelerator include calcium nitrite, calcium nitrate, calcium chloride, calcium hydroxide, sodium nitrite, potassium nitrite, sodium nitrate, potassium nitrate, sodium chloride, potassium chloride, etc. Among the above compounds, the accelerator preferably contains an alkali metal nitrite, more preferably contains calcium nitrite, and even more preferably is calcium nitrite.

[0064] The upper limit of the accelerator content is 12.0 parts by mass or less per 100 parts by mass of the cement, but may be, for example, 11.5 parts by mass or less, 11.0 parts by mass or less, 10.5 parts by mass or less, 10.0 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, or 6.0 parts by mass or less. By keeping the upper limit of the accelerator content within the above range, the occurrence of abnormal setting when the reaction of granulated blast furnace slag or the like is excessively promoted can be more reliably suppressed. The lower limit of the accelerator content is 0.2 parts by mass or more per 100 parts by mass of the cement, but may be, for example, 0.5 parts by mass or more, 1.0 parts by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, or 5.0 parts by mass or more. By keeping the lower limit of the accelerator content within the above range, the reaction of granulated blast furnace slag can be further promoted. The content of the accelerator may be adjusted within the above range, and may be, for example, 0.2 to 12.0 parts by mass, or 5.0 to 12.0 parts by mass per 100 parts by mass of the cement.

[0065] The content of the accelerator in this specification is determined by subjecting the powdered composition to X-ray diffraction measurement and quantifying the content of the accelerator by Rietveld analysis. When preparing a hydraulic composition by oneself, the content of the accelerator coincides with the blending amount, and therefore the above-mentioned analysis is not required.

[0066] The hydraulic composition may further contain other components in addition to cement and an accelerator, such as silica powder, other calcium-containing inorganic powders, fly ash and silica fume, inorganic minerals containing Si and Al, a water-reducing agent for concrete, and a retarder.

[0067] [Method for producing hydraulic composition] The hydraulic composition described above can be produced, for example, by the following method. One embodiment of a method for producing a hydraulic composition includes a first step of mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum to prepare cement, and a second step of mixing 0.2 to 12.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement.

[0068] In the first step, each component constituting the raw material may be crushed. When crushing is performed in the first step, the order of mixing and crushing is not particularly limited. That is, the various components may be mixed and then crushed, or the various components may be crushed and then mixed, or the various components may be mixed and crushed simultaneously. The mixing of the various components in the first step may be performed using a mixer such as a pan mixer, a tilting mixer, or a ribbon mixer, or may be mixed and crushed using a crusher such as a ball mill, a vertical roller mill, or a roller press, or the various components may be crushed individually and then mixed using a mixer such as a mechanical mixer.

[0069] The first step includes adjusting the amount of the alkaline activator to 0.1 to 5.0 mass% and the amount of the granulated blast furnace slag to 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag, and adjusting the content of gypsum in the cement to 2.5 to 10.0 mass% in terms of SO3.

[0070] In the second step, cement and an accelerator are mixed. The mixing method may be the same as or different from that in the first step. Other components may be blended in the second step or in a step other than the first and second steps. Examples of other components include silica powder, other calcium-containing inorganic powders, fly ash, and inorganic minerals containing Si and Al.

[0071] [Method of manufacturing the hardened product] The hydraulic composition described above is suitable as a raw material for preparing hardened products such as mortar and concrete. That is, one embodiment of a method for producing a hardened product includes a step of blending 50 parts by mass of water with 100 parts by mass of the hydraulic composition described above. In the above-mentioned production method, in addition to water, for example, fine aggregate, coarse aggregate, admixtures, etc. may also be mixed to produce a hardened mortar.

[0072] The hydraulic composition may be produced by the same method as the hydraulic composition described above. That is, the method for producing a hardened body may include, for example, a first step of preparing cement by mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum, a second step of mixing 0.2 to 12.0 parts by mass of an accelerator with 100 parts by mass of the cement to obtain a hydraulic composition, and a third step of mixing 50 parts by mass of water with 100 parts by mass of the hydraulic composition, wherein the first step includes adjusting the amount of the alkaline activator to 0.1 to 5.0% by mass and the amount of the granulated blast furnace slag to 95.0 to 99.9% by mass, based on a total of 100% by mass of the alkaline activator and the granulated blast furnace slag, and adjusting the content of gypsum in the cement to 2.5 to 10.0% by mass in terms of SO3.

[0073] Examples of water include tap water, distilled water, deionized water, etc. The amount of water used may be 20 to 100 parts by mass, or 40 to 70 parts by mass, per 100 parts by mass of the hydraulic composition.

[0074] The fine aggregate may be one specified in JIS A 5005:2020 "Crushed Stone and Crushed Sand for Concrete." Examples of fine aggregate include river sand, land sand, sea sand, crushed sand, silica sand, copper slag fine aggregate, and electric furnace oxidizing slag fine aggregate. When using fine aggregate, the amount of fine aggregate used may be, for example, 50 to 500 parts by mass, 100 to 300 parts by mass, or 200 to 250 parts by mass per 100 parts by mass of the hydraulic composition.

[0075] The coarse aggregate may be one specified in JIS A 5005:2020 "Crushed stone and crushed sand for concrete." Examples of coarse aggregate include gravel and crushed stone. When using coarse aggregate, the amount of coarse aggregate used may be, for example, 50 to 500 parts by mass, 100 to 300 parts by mass, or 200 to 250 parts by mass per 100 parts by mass of the hydraulic composition.

[0076] Fine aggregate and coarse aggregate can also be used in combination. In this case, the total amount of the fine aggregate and coarse aggregate used may be 100 to 300 parts by mass, or 200 to 250 parts by mass, per 100 parts by mass of the hydraulic composition.

[0077] Examples of the admixture include air-entraining agents, water-reducing agents, air-entraining water-reducing agents, high-performance water-reducing agents, superplasticizers, antifoaming agents, shrinkage-reducing agents, setting accelerators, setting retarders, and thickeners. The amount of the admixture used may be, for example, 0.01 to 2 parts by mass per 100 parts by mass of the above-mentioned hydraulic composition.

[0078] [Method for suppressing variations in compressive strength of compositions with low alkaline irritant content] By applying the above findings, a method (a method for suppressing fluctuations in compressive strength) can be provided for preparing a composition with a low content of alkaline activator (e.g., a low-cement hydraulic composition) that exhibits low fluctuations in compressive strength and exhibits expected compressive strength even when precise measurement is not possible. One embodiment of the method for suppressing fluctuations in compressive strength includes adjusting the content of gypsum in a composition containing cement comprising an alkaline activator, granulated blast furnace slag, and gypsum to 2.5 to 10.0 mass% SO3 equivalent relative to the total amount of the cement, and adjusting the content of the accelerator to 0.2 to 12.0 mass% relative to 100 mass parts of the cement. This method is particularly effective when the component composition of the composition is such that the content of the alkaline activator is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on 100 mass% of the total of the alkaline activator and the granulated blast furnace slag. By using this method, it is possible to prepare a hydraulic composition that can exhibit compressive strength sufficient for practical use even in a range of low alkaline activator content, which was previously impossible to use when measured at the actual equipment level.

[0079] In the method for suppressing fluctuations in compressive strength, it is more preferable to adjust the gypsum content to 5.0 to 10.0 mass% in terms of SO3 relative to the total amount of the cement, and to adjust the accelerator content to 6.0 to 10.0 parts by mass relative to 100 parts by mass of the cement.

[0080] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be applied to each other. [Example]

[0081] The present disclosure will be described in more detail below with reference to examples, comparative examples, and reference examples, although the present disclosure is not limited to the following examples.

[0082] [Raw materials for hydraulic compositions] The following materials were used as raw materials for the hydraulic composition.

[0083] (cement clinker) The cement clinker used was the type commonly used to prepare ordinary Portland cement. In Table 1, ordinary Portland cement clinker is referred to as "clinker." The chemical composition of the cement clinker was measured in accordance with JIS R 5202:2015 "Methods for chemical analysis of cement." The results are shown in Table 1.

[0084] (plaster) The gypsum used was dehydrated gypsum dihydrate, a by-product of coal-fired power plants, and reagent anhydrous gypsum. In Table 1, dehydrated gypsum dihydrate is referred to as gypsum dihydrate. The chemical composition of the gypsum was measured in accordance with JIS R 5202:2015 "Methods for Chemical Analysis of Cement." The results are shown in Table 1.

[0085] (granulated blast furnace slag) The granulated blast furnace slag used was ground granulated blast furnace slag without gypsum addition. The chemical composition of the ground granulated blast furnace slag was measured in accordance with JIS R 5202:2015 "Methods for chemical analysis of cement." The results are shown in Table 1.

[0086] [Table 1]

[0087] In Table 1, the C / S ratio refers to the CaO content / SiO2 content. The ignition loss (also abbreviated as ig.loss) in Table 1 is a value measured at a heating temperature of 700°C in accordance with the method described in "5.2 For materials other than blast furnace cement and blast furnace slag" in "5. Method for determining ignition loss" of JIS R 5202:2010.

[0088] (accelerator) An inorganic accelerator, calcium nitrite monohydrate (hereinafter sometimes referred to as CN) manufactured by Kishida Chemical Co., Ltd., was used.

[0089] [Example 1] Cement was prepared by mixing 3% by mass of ordinary Portland cement clinker, 82% by mass of granulated blast furnace slag, and 15% by mass of gypsum dihydrate. Based on the total amount of ordinary Portland cement and granulated blast furnace slag, the amount of ordinary Portland cement was 3.5% by mass and the amount of blast furnace cement slag was 96.5% by mass. The gypsum content in the cement was 6.9% by mass, calculated as SO3.

[0090] Next, calcium nitrite monohydrate was mixed as an accelerator so that the amount of the accelerator was 2 parts by mass per 100 parts by mass of the cement, thereby preparing the hydraulic composition of Example 1.

[0091] [Example 2] Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending amounts of ordinary Portland cement clinker and granulated blast furnace slag were changed as shown in Table 2.

[0092] [Examples 3 and 4] Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending amounts of ordinary Portland cement clinker and granulated blast furnace slag, and the blending amount of the accelerator were changed as shown in Table 2.

[0093] [Comparative Example 1] A hydraulic composition was prepared in the same manner as in Example 1, except that no accelerator was added.

[0094] [Comparative Examples 2 and 3] Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending amounts of ordinary Portland cement clinker and granulated blast furnace slag were changed as shown in Table 4 and no accelerator was blended.

[0095] [Reference example] A composition was prepared containing 96.5% by mass of ordinary Portland cement clinker and 3.5% by mass of dihydrate gypsum. The resulting composition was designated Reference Example 1 and was used as an example of ordinary Portland cement that does not use granulated blast furnace slag.

[0096] [Table 2]

[0097] [Evaluation of hydraulic composition: compressive strength] The compressive strength of the hydraulic compositions prepared as described above was measured at ages of 7 days and 28 days according to the method described below. The results are shown in Table 3.

[0098] The compressive strength was evaluated using mortar compositions obtained by blending a hydraulic composition, fine aggregate, and water. Specifically, for each of the hydraulic compositions prepared in the Examples, Comparative Examples, and Reference Examples, 200 parts by mass of sand (standard sand / manufactured by the Cement Association) as fine aggregate and 50 parts by mass of water were blended with 100 parts by mass of the hydraulic composition to prepare a mortar composition for evaluation. The blending ratio was adjusted so that the ratio of hydraulic composition:sand:water was 100:300:50 (mass ratio, blending in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement").

[0099] Each of the obtained mortar compositions was used to prepare a hardened mortar. First, the mortar composition was mixed as a mortar in a thermostatic chamber at 20°C and packed into a 4 cm x 4 cm x 16 cm formwork (prepared in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement"). The formwork was stored in a humidity chamber and cured for 24 hours. After 24 hours of curing, the formwork was demolded to obtain a hardened mortar. The obtained hardened mortar was cured in water for 7 days (7-day age) in a thermostatic chamber at 20°C. The hardened mortar after underwater curing was used as a test specimen to measure the compressive strength of the 7-day-old hardened mortar. Similarly, the obtained hardened mortar was cured in water for 28 days (28-day age) in a thermostatic chamber at 20°C, and the compressive strength of the 28-day-old hardened mortar was measured. The compressive strength measurement was performed in accordance with JIS R 5201:1992 "Physical Testing Methods for Cement." The results are shown in Table 3.

[0100] [Table 3]

[0101] As shown in Tables 2 and 3, when the results of accelerator-free compositions with ordinary Portland cement clinker contents of 3% by mass (Comparative Example 1), 1% by mass (Comparative Example 2), and 5% by mass (Comparative Example 3) are compared, it is clear that, as shown in previous research results, there is a large variation in compressive strength depending on the amount of ordinary Portland cement clinker added. In particular, it has been confirmed that, compared to when the ordinary Portland cement clinker content is 1% by mass, when the ordinary Portland cement clinker content is increased to 3% by mass, there is a significant decrease in compressive strength, and it has been confirmed that it is difficult to deploy such a system industrially.

[0102] On the other hand, as shown in Tables 2 and 3, it was confirmed that the fluctuations in compressive strength exhibited by the hydraulic compositions prepared in Examples 1 to 4 were relatively small, despite the fact that the blending amount of ordinary Portland cement clinker was in the low range of 1 to 5 mass %. Furthermore, it was shown that the hydraulic composition prepared in Example 2, in which most of the ordinary Portland cement clinker was replaced with granulated blast furnace slag and the blending amount of ordinary Portland cement clinker was only 1 mass %, could exhibit compressive strength that exceeded that of the conventional ordinary Portland cement (Reference Example 1). It was confirmed that this composition is useful not only from the viewpoint of reducing CO2 emissions but also as a new candidate material for preparing hardened bodies with excellent strength.

[0103] Next, in order to confirm the effect of each component of the hydraulic composition, hydraulic compositions of various comparative examples were prepared and evaluated.

[0104] [Comparative Examples 4 to 7] Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending amounts of granulated blast furnace slag and gypsum dihydrate were changed as shown in Table 4.

[0105] [Table 4]

[0106] [Evaluation of hydraulic composition: compressive strength] The compressive strength of the hydraulic compositions prepared as described above was measured at ages of 7 and 28 days in the same manner as in Example 1. The results are shown in Table 5. Table 5 also lists the evaluation results of Examples 1 and 2 for comparison with the examples.

[0107] [Table 5]

[0108] As shown in Tables 4 and 5, it was confirmed that even when an accelerator was added, in Comparative Examples 4 to 7, where the amount of gypsum added was outside the specified range of the present disclosure, sufficient compressive strength was not obtained.

[0109] Table 6 also shows the evaluation results for the hydraulic composition when the blending amount of ordinary Portland cement is 5 mass %.

[0110] [Table 6]

[0111] As shown in Tables 2 and 6, it was confirmed that in compositions that do not contain an accelerator, when the content of ordinary Portland cement clinker increases to 5% by mass, it is more difficult to exhibit long-term compressive strength than when the content of ordinary Portland cement clinker is around 3% by mass. On the other hand, the results of Examples 3 and 4 confirm that even within this range of ordinary Portland cement content, by adjusting the amount of gypsum and the amount of accelerator, it is possible to exhibit compressive strength that is sufficient for practical use. [Industrial Applicability]

[0112] According to the present disclosure, it is possible to provide a hydraulic composition in which fluctuations in compressive strength exhibited by hardening are suppressed even when the amount of cement clinker varies in a range where the amount of cement clinker is 5% by mass or less, and a method for producing the same. According to the present disclosure, it is also possible to provide a method for producing a hardened body using the above-mentioned hydraulic composition. According to the present disclosure, it is also possible to provide a method for suppressing fluctuations in compressive strength even when the amount of cement clinker varies.

Claims

1. Cement comprising an alkali activator, granulated blast furnace slag, and gypsum; a promoter; The content of the alkaline activator is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag, The content of the gypsum in the cement is SO ３ converted to 2.5 to 10.0 mass%; The content of the accelerator is 0.2 to 12.0 parts by mass relative to 100 parts by mass of the cement, The alkaline irritant includes cement clinker, The hydraulic composition, wherein the accelerator comprises calcium nitrite.

2. A hydraulic composition as described in claim 1, wherein the alkaline stimulant contains at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime.

3. The hydraulic composition according to claim 1 or 2, wherein the gypsum contains at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate.

4. The hydraulic composition according to any one of claims 1 to 3, wherein the basicity of the granulated blast furnace slag is 1.60 to 1.

95.

5. The hydraulic composition according to any one of claims 1 to 4, wherein the content of aluminum oxide in the granulated blast furnace slag is 10.0 mass% or more.

6. The hydraulic composition according to any one of claims 1 to 5, wherein the content of the alkaline activator is 0.2 to 3.5 mass% and the content of the granulated blast furnace slag is 96.5 to 99.8 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag.

7. A first step of preparing cement by mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum; A second step of mixing 0.2 to 12.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement, The first step The amount of the alkaline stimulant is adjusted to 0.1 to 5.0 mass% and the amount of the granulated blast furnace slag is adjusted to 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline stimulant and the granulated blast furnace slag; and The content of gypsum in the cement is determined by SO ３ and adjusting the content to 2.5 to 10.0 mass% in terms of total mass, The alkaline irritant includes cement clinker, The method for producing a hydraulic composition, wherein the accelerator contains calcium nitrite.

8. A first step of preparing cement by mixing raw materials including an alkaline activator, granulated blast furnace slag, and gypsum; a second step of mixing 0.2 to 12.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement to obtain a hydraulic composition; a third step of blending 50 parts by mass of water with 100 parts by mass of the hydraulic composition, The first step The amount of the alkaline stimulant is adjusted to 0.1 to 5.0 mass% and the amount of the granulated blast furnace slag is adjusted to 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline stimulant and the granulated blast furnace slag; and The content of gypsum in the cement is determined by SO ３ and adjusting the content to 2.5 to 10.0 mass% in terms of total mass, The method for producing a hardened body, wherein the alkaline activator contains cement clinker.

9. A composition containing an alkaline irritant, granulated blast furnace slag, and cement containing gypsum, The content of gypsum is determined based on the total amount of the cement. ３ Adjusting the amount to be 2.5 to 10.0 mass% in terms of total mass; and and adjusting the content of the accelerator to 0.2 to 12.0 parts by mass per 100 parts by mass of the cement; In the composition, the content of the alkaline activator is 0.1 to 5.0 mass% and the content of the granulated blast furnace slag is 95.0 to 99.9 mass%, based on a total of 100 mass% of the alkaline activator and the granulated blast furnace slag, The alkaline irritant includes cement clinker, A method for reducing variation in compressive strength, wherein the accelerator comprises calcium nitrite.

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