Method of producing hydraulic composition and hydraulic composition

Abstract

To provide a method for producing a hydraulic composition capable of producing a hardened body excellent in compressive strength over a long period of time from an initial stage.SOLUTION: There is provided a method for producing a hydraulic composition which comprises preparing cement by mixing an alkali activator, a granulated blast furnace slag and a gypsum having a Blaine specific surface area of 1500 to 3500 cm2 / g, wherein the content of SO3 detected by X-ray fluorescence analysis in the cement is 1.5 to 7.0 mass% based on the total amount of the cement, the content of the alkali activator is 10.0 to 50.0 mass%, the content of the granulated blast furnace slag is 45.0 to 75.0 mass% and the content of the gypsum is 2.0 to 15.0 mass%, based on 100 mass% of the total of the cement.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a hydraulic composition, and a hydraulic composition. [Background technology]

[0002] In cement production, large amounts of CO2 are generated during fuel combustion and decarbonation of raw materials, and in response to increasing demands for measures to combat global warming, there is a demand to reduce the amount of CO2 generated in cement production.Since a large amount of CO2 is generated during the preparation of cement clinker, which is the raw material, cement in which part of the cement clinker is replaced with an admixture is being widely studied from the perspective of reducing CO2 emissions.

[0003] It is generally believed that increasing the amount of admixture reduces the compressive strength of the hardened body obtained by hardening cement. Therefore, it is important to achieve the desired performance, such as practical compressive strength, while blending the admixture. Among admixtures, steel slag, such as blast furnace slag, is expected to increase the long-term strength of concrete and improve its salt-blocking effect. Therefore, research is being conducted on cement that uses steel slag as an admixture and increases its mixing ratio.

[0004] Blast-furnace cement, in which part of the cement clinker is replaced with granulated blast-furnace slag (BFS), is classified according to the replacement ratio. JIS R 5211:2019 specifies two types of blast-furnace cement: Type B, which contains more than 30% but not more than 60% blast-furnace slag by mass, and Type C, which contains more than 60% but not more than 70% blast-furnace slag by mass. However, there are no specifications for cement containing blast-furnace slag in excess of 70% by mass. Currently, cement containing less than 30% blast-furnace slag is considered to have unstable compressive strength and is difficult to use in practical applications. Despite the above-mentioned circumstances, cement compositions containing a higher blast-furnace slag content than Type C blast-furnace slag are being investigated with the aim of reducing CO2 emissions (e.g., Non-Patent Documents 1 and 2). However, in the example described in Non-Patent Document 1, it has been confirmed that when the cement clinker content exceeds 1% by mass, approximately 3-5% by mass, the hardening reaction of the cement composition does not proceed, resulting in a significant decrease in the compressive strength of the resulting hardened product. That is, in the region where the amount of blast furnace slag is extremely large, even a slight change in the composition of the cement composition results in a large fluctuation in the manifested strength.

[0005] Furthermore, the influence of gypsum fineness on the early strength development and hydration reaction of cement mixed with ground granulated blast furnace slag has also been studied (for example, Non-Patent Document 3). Non-Patent Document 3 states that when gypsum with a high fineness is added to cement mixed with 40% by mass of blast furnace slag to 50% by mass of cement, strength development improves up to an age of 3 days, but the strength development tends to decrease at an age of 7 days. Specifically, in a blend of 40% by mass of blast furnace slag, 50% by mass of ordinary cement, and 10% by mass of anhydrous gypsum powder, the gypsum powder is added to a mixture with a Blaine specific surface area of ​​3700 cm. 2 / g and 10000cm 2 / g, the material age is 10,000 cm 2 / g has a compressive strength of 3N / mm 2 The degree is high, and at 7 days old it is 3700 cm 2 / g has a compressive strength of 10N / mm 2 It has been shown that it will be higher than this. [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> [Non-patent document 2] Toshio Yonezawa et al., "Energy and CO2 Minimum (ECM) Cement and Concrete System," Concrete Engineering, Japan Concrete Institute, 2010, Vol. 48, No. 9, pp. 69-73 [Non-patent document 3] Adachi, Takeshi et al., "Effect of gypsum fineness on early strength development and hydration reaction of cement mixed with ground granulated blast furnace slag," Proceedings of the Cement and Concrete Journal, 2021, Vol. 75, pp. 90-96 Summary of the Invention [Problem to be solved by the invention]

[0007] It would be useful to provide a hydraulic composition that exhibits sufficient compressive strength even in the range of a high blend amount of blast furnace slag.

[0008] An object of the present disclosure is to provide a method for producing a hydraulic composition that can produce a hardened product that has excellent compressive strength from the initial stage to the long term, and the hydraulic composition. [Means for solving the problem]

[0009] According to the inventors' research, when conventional hydraulic compositions harden, a layer of ettringite (a compound represented by 3CaO·Al2O3·3CaSO4·32H2O) forms on the surface of granulated blast furnace slag particles at a relatively early stage of hardening. This inhibits the reaction of the granulated blast furnace slag itself, resulting in a lower compressive strength of the hardened body than would be expected if the reaction time were extended. Furthermore, the inventors hypothesized that controlling the amount of sulfate ions and sulfite ions supplied to the system during hardening of the hydraulic composition could inhibit ettringite from covering the entire surface of the granulated blast furnace slag particles, and that reducing the amount of SO3 in the cement and reducing the specific surface area of ​​gypsum, which is the SO3 supply source, would be effective means for this. The present disclosure is based on the above findings and technical ideas.

[0010] One aspect of the present disclosure provides the following [1].

[0011] [1] Alkaline stimulant, granulated blast furnace slag, and blaine with a specific surface area of ​​1500 to 3500 cm 2 / g of gypsum to prepare cement; The content of SO3 in the cement detected by X-ray fluorescence analysis is 1.5 to 7.0 mass% based on the total amount of the cement, Based on 100% by mass of the cement in total, The content of the alkaline irritant is 10.0 to 50.0% by mass, The content of the granulated blast furnace slag is 45.0 to 75.0 mass%, The gypsum content is 2.0 to 15.0% by mass. A method for producing a hydraulic composition.

[0012] The above manufacturing method uses gypsum whose fineness has been adjusted in advance, and employs a method of manufacturing cement so that the amount of SO3 in the cement falls within a predetermined range. The hydraulic composition obtained in this way supplies sulfate ions and the like to the reaction system during the hydration reaction more slowly than conventional hydraulic compositions, suppresses the formation of ettringite coatings on the particle surfaces of the granulated blast furnace slag, and allows the granulated blast furnace slag to react sufficiently, making it possible to manufacture a hardened body that has excellent compressive strength from the initial stage to the long term.

[0013] The above [1] may be the following [2].

[0014] [2] The method according to [1], further comprising mixing 0.2 to 4.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement.

[0015] One aspect of the present disclosure also provides the following [3].

[0016] [3] The cement comprises an alkaline irritant, granulated blast furnace slag, and gypsum; The content of SO3 detected by X-ray fluorescence analysis for the cement is 1.5 to 7.0 mass%; Based on 100% by mass of the cement in total, The content of the alkaline irritant is 10.0 to 50.0% by mass, The content of the granulated blast furnace slag is 45.0 to 75.0 mass%, The gypsum content is 2.0 to 15.0% by mass, the gypsum includes anhydrite; The Blaine specific surface area of ​​the gypsum is 1500 to 3500 cm 2 / g of a hydraulic composition.

[0017] The hydraulic composition contains gypsum with a Blaine value adjusted to a predetermined range, and is mixed with an alkali activator, granulated blast furnace slag, and gypsum so that the amount of SO3 in the cement is within a predetermined range. A hydraulic composition having such a composition supplies sulfate ions and the like to the reaction system during the hydration reaction more slowly than conventional hydraulic compositions, suppresses the formation of an ettringite film on the particle surfaces of the granulated blast furnace slag, and allows the granulated blast furnace slag to react sufficiently, making it possible to produce a hardened body that has excellent compressive strength from the initial stage to the long term.

[0018] The above [3] may be any of the following [4] to [9].

[0019] [4] further comprising an accelerator; The hydraulic composition according to [3], wherein the content of the accelerator is 0.2 to 4.0 parts by mass per 100 parts by mass of the cement. [5] The hydraulic composition according to [4], wherein the accelerator contains at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts. [6] The hydraulic composition according to [4] or [5], wherein the accelerator is a salt having a monovalent anion. [7] The hydraulic composition according to any one of [3] to [6], wherein the alkaline activator contains at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime. [8] The hydraulic composition according to any one of [3] to [7], wherein the basicity of the granulated blast furnace slag is 1.60 to 1.95. [9] The hydraulic composition according to any one of [3] to [8], wherein the content of aluminum oxide in the granulated blast furnace slag is 10.0 mass % or more. [Effects of the Invention]

[0020] According to the present disclosure, it is possible to provide a method for producing a hydraulic composition that can produce a hardened product that has excellent compressive strength from the early stage to the long term, and the hydraulic composition. DETAILED DESCRIPTION OF THE INVENTION

[0021] 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.

[0022] 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.

[0023] [Method for producing hydraulic composition] One embodiment of the method for producing a hydraulic composition comprises an alkali activator, granulated blast furnace slag, and a slag having a Blaine specific surface area of ​​1500 to 3500 cm 2 / g of gypsum to prepare cement. The cement comprises the alkaline activator, the granulated blast furnace slag, and the gypsum. If the fineness of the cement needs to be adjusted, this can be done by previously pulverizing at least one of the alkaline activator and the granulated blast furnace slag to adjust the Blaine specific surface area of ​​the constituent components. The production method may further include a step of pulverizing at least one of the alkaline activator and the granulated blast furnace slag. On the other hand, when pulverizing the cement mixed with the alkaline activator, the granulated blast furnace slag, and the gypsum in the production method, the Blaine specific surface area of ​​the gypsum is adjusted so as not to fall outside the range. In the production method, preferably, pulverizing the cement mixed with the alkaline activator, the granulated blast furnace slag, and the gypsum is not performed.

[0024] In the manufacturing method, the SO3 content of the cement, as detected by X-ray fluorescence analysis, is adjusted to 1.5 to 7.0 mass% based on the total mass of the cement. The SO3 content includes that derived from components in the alkaline activator and granulated blast furnace slag, in addition to gypsum. The SO3 content can be adjusted, for example, by adjusting the blending amounts of the alkaline activator, granulated blast furnace slag, and gypsum.

[0025] The blending amounts of the alkaline activator, the granulated blast furnace slag, and the gypsum can be adjusted so that the contents of each component in the resulting cement are within the following ranges: based on a total of 100% by mass of the cement, the content of the alkaline activator is 10.0 to 50.0% by mass, the content of the granulated blast furnace slag is 45.0 to 75.0% by mass, and the content of the gypsum is 2.0 to 15.0% by mass.

[0026] (Alkaline stimulant) 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.

[0027] The Portland cement clinker may be Portland cement clinker used to prepare various Portland cements specified in JIS R 5210:2003 "Portland Cement." Examples of the various Portland cements include ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, and low-heat Portland cement. The Portland cement clinker may be Portland cement clinker used to prepare ordinary Portland cement and high-early-strength Portland cement.

[0028] The mineral composition of Portland cement clinker can be calculated by the Bogue formula. Here, the Bogue formula is a widely used formula for calculating the content of main minerals in Portland cement clinker from the content ratios of chemical compositions. By using the Bogue formula shown below, the contents 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 formulas, "%" means "mass %". The chemical formulas represent the content ratios (mass %) of each compound shown by the chemical analysis values according to JIS R 5204:2019 "Fluorescent X-ray Analysis Method for Cement".

[0029] <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 [%]

[0030] The amount of C3A in Portland cement clinker is preferably 0.5 to 1l.0 mass %, more preferably 0.5 to 10.5 mass %, still more preferably 0.5 to 10.0 mass % or less, and particularly preferably 0.5 to 9.5 mass %. When the amount of C3A in Portland cement clinker is within the above range, it is possible to further reduce the amount of gypsum for suppressing the hydration reaction in the hydraulic composition, and the hydration reaction of blast furnace slag can be more fully exerted.

[0031] The fineness of the Portland cement clinker may be adjusted in advance 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.

[0032] The Blaine specific surface area in this specification is a value obtained by the fineness test of JIS R 5201:2015 "Physical Testing Methods for Cement" and measurement using a Blaine air permeability device, and is one of the physical properties that indicate fineness.

[0033] The amount of the alkaline activator may be adjusted so that the content of the alkaline activator in the cement falls within the range shown below. The content of the alkaline activator is 10.0 to 50.0 mass% based on 100 mass% of the cement. The upper limit of the content of the alkaline activator may be, for example, 50.0 mass% or less, 42.5 mass% or less, 35.0 mass% or less, or 27.5 mass% or less based on 100 mass% of the cement. When the upper limit of the content of the alkaline activator falls within the above range, the rapid reaction of the granulated blast furnace slag due to alkaline activation can be further suppressed, and sufficient strength can be exhibited over the long term. The lower limit of the content of the alkaline activator may be, for example, 10.0 mass% or more, 15.0 mass% or more, 20.0 mass% or more, or 25.0 mass% or more based on 100 mass% of the cement. When the lower limit of the content of the alkali activator is within the above range, the initial reactivity of the granulated blast furnace slag can be further improved, and the granulated blast furnace slag can exhibit more sufficient strength.

[0034] The content of alkaline activator in this specification refers to a value determined by the following method. The alkaline activators, Portland cement clinker, slaked lime, and quicklime, are detected by Rietveld analysis using an internal standard method based on X-ray diffraction measurement of the hydraulic composition powder, quantifying the Portland cement clinker, slaked lime, and quicklime, calculating their total amount, and determining the content of alkaline activator. Specifically, first, either corundum (aluminum oxide) or periclase (magnesium oxide) is used as an internal standard substance, and this is added to the powder whose alkaline activator content is to be determined so that the content is 10% by mass. Next, the powder is wet-pulverized in acetone using an agate mortar to make the particle size as uniform as possible. The acetone is then fully evaporated, and X-ray diffraction measurement is performed. Of the crystalline phases detected in the measurement sample (alite, belite, aluminate phase, ferrite phase, gypsum, sylvite, halite, lime, portlandite, or any one of the internal standards), Rietveld analysis is performed with the internal standard fixed at 10 mass%. Here, the amorphous phase calculated based on the internal standard is treated as glassy granulated blast furnace slag, and the total amount of Portland cement clinker, slaked lime, and quicklime is calculated, and the content of the alkali activator is determined.

[0035] (granulated blast furnace slag) Granulated blast furnace slag is a type of slag with a high vitrification rate, and is a sand-like slag that is crushed by injecting a large amount of pressurized water into molten slag produced in a blast furnace to rapidly cool it.

[0036] The granulated blast furnace slag may be, for example, commercially available, or slag equivalent to granulated blast furnace slag may be prepared and used.

[0037] The lower limit of the aluminum oxide content (also referred to as the Al2O3 content) in the granulated blast furnace slag may be, for example, 10.0 mass% or more, 11.0 mass% or more, 12.0 mass% or more, or 13.0 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. Note that the latent hydraulic properties refer to the property of initiating a hydration reaction by adding an alkaline activator. The upper limit of the Al2O3 content in the granulated blast furnace slag may be, for example, 14.5 mass% or less, or 14.3 mass% or less. When the Al2O3 content in the granulated blast furnace slag is within the above range, the deterioration of the long-term strength development of the resulting hydraulic composition can be further suppressed. 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%.

[0038] 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.

[0039] 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.

[0040] 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 adding an 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.

[0041] The basicity (JIS 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).

[0042] The fineness of the granulated blast furnace slag may be adjusted in advance from the viewpoint of further improving the performance of the hydration reaction in the hydraulic composition. The Blaine specific surface area of ​​the 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 55.00 cm 2 / g.

[0043] The amount of granulated blast furnace slag may be adjusted so that the content of granulated blast furnace slag in the cement falls within the ranges shown below. The content of the granulated blast furnace slag is 45.0 to 75.0% by mass, based on 100% by mass of the cement. The upper limit of the content of the granulated blast furnace slag may be, for example, 75.0% by mass or less, 70.0% by mass or less, 65.0% by mass or less, or 60.0% by mass or less, based on 100% by mass of the cement. When the upper limit of the content of the granulated blast furnace slag falls within the above range, the reactivity of the granulated blast furnace slag can be made more sufficient. The lower limit of the content of the granulated blast furnace slag may be, for example, 45.0% by mass or more, 47.5% by mass or more, 50.0% by mass or more, or 55.0% by mass or more, based on 100% by mass of the cement. When the lower limit of the content of 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.

[0044] 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.

[0045] (plaster) In the above manufacturing method, the gypsum has a Blaine specific surface area of ​​1500 to 3500 cm 2 It is generally believed that the higher the Blaine specific surface area of ​​gypsum, the better the reactivity and the more advantageous it is for the hydraulic composition to develop strength, but in the composition of the present disclosure, the use of gypsum with a relatively low fineness can actually increase the strength developed by the hydraulic composition.

[0046] The upper limit of the Blaine specific surface area of ​​the gypsum is, for example, 3500 cm 2 / g or less, 3000cm 2 / g or less, 2500cm 2 / g or less, or 2000cm 2 / g or less. When the upper limit of the Blaine specific surface area is within the above range, the progress of the hydration reaction of the hydraulic composition can be controlled slowly, and the formation of an ettringite film on the particle surfaces of the granulated blast furnace slag can be further suppressed. The lower limit of the Blaine specific surface area of ​​the gypsum can be, for example, 1500 cm 2 / g or more, 1600cm 2 / g or more, 1700cm 2 / g or more, or 1800cm 2 When the lower limit of the Blaine specific surface area is within the above range, a significant delay in the gypsum hydration reaction can be avoided, and the hydration reaction of the hydraulic composition can proceed more smoothly.

[0047] The gypsum may be, for example, gypsum dihydrate, gypsum hemihydrate, anhydrous gypsum, or the like. The gypsum may contain gypsum dihydrate or anhydrous gypsum, and it is more preferable that the gypsum contains anhydrous gypsum. Examples of the anhydrous gypsum include dehydrated gypsum dihydrate and natural gypsum dihydrate. Examples of the anhydrous gypsum include recycled anhydrous gypsum, hydrofluoric anhydrous gypsum, and natural anhydrous gypsum. The gypsum may be gypsum obtained by recycling waste gypsum board (recycled anhydrous gypsum, etc.).

[0048] The amount of gypsum may be adjusted so that the gypsum content in the cement falls within the range shown below. The gypsum content is 2.0 to 15.0% by mass, based on 100% by mass of the cement. The upper limit of the gypsum content may be, for example, 15.0% by mass or less, 13.0% by mass or less, 11.0% by mass or less, 9.0% by mass or less, or 7.0% by mass or less, based on 100% by mass of the cement. When the upper limit of the gypsum content falls within the above range, the initial and long-term strength development can be further improved. The lower limit of the gypsum content may be, for example, 2.0% by mass or more, 3.0% by mass or more, 4.0% by mass or more, 5.0% by mass or more, or 6.0% by mass or more, based on 100% by mass of the cement. By setting the lower limit of the gypsum content within the above range, the hydration reaction of the granulated blast furnace slag is made more favorable, the hardening of the hydraulic composition after mixing with water is accelerated, and the early strength development can be further improved. The gypsum content may be adjusted within the above range, and may be, for example, 2.0 to 15.0 mass % or 4.0 to 15.0 mass % based on 100 mass % of the cement.

[0049] In the above manufacturing method, the amount of SO3 detected by X-ray fluorescence analysis of the cement may be adjusted to fall within a predetermined range. The amount of SO3 in the cement includes that derived from the alkali activator and granulated blast furnace slag, which are components other than gypsum. Therefore, the amount of SO3 in the cement can be adjusted by adjusting the components used and their amounts.

[0050] The SO3 content of the cement, as detected by X-ray fluorescence analysis, is 1.5 to 7.0 mass% based on the total amount of the cement. The upper limit of the SO3 content may be, for example, 7.0 mass% or less, 6.0 mass% or less, 5.0 mass% or less, or 4.0 mass% or less based on the total amount of the cement. When the upper limit of the SO3 content is within the above range, when the resulting hydraulic composition undergoes a hydration reaction, the supply of sulfate ions and the like to the reaction system is more gradual than in conventional hydraulic compositions, which further suppresses the formation of an ettringite film on the particle surfaces of the granulated blast furnace slag, allowing the granulated blast furnace slag to react more fully, resulting in the production of a hardened body with superior initial and long-term compressive strength. The lower limit of the SO3 content may be, for example, 1.5 mass% or more, 2.0 mass% or more, 2.5 mass% or more, or 3.0 mass% or more based on the total amount of the cement. When the lower limit of the SO3 content is within the above range, it is possible to more sufficiently suppress the decrease in strength that accompanies a decrease in the amount of ettringite produced due to a deficiency of sulfates.

[0051] The SO3 content in this specification means a value measured in accordance with the method described in JIS R 5204:2019 "Fluorescent X-ray analysis method for cement."

[0052] In the method for producing the hydraulic composition, the alkaline activator, the granulated blast furnace slag, and the gypsum may be mixed at once, or the alkaline activator and the granulated blast furnace slag may be mixed in advance, and then the gypsum may be blended and mixed.

[0053] Mixing when preparing cement is carried out under conditions that do not significantly change the Blaine specific surface area of ​​the gypsum. A mixer without a grinding function may be used for such mixing. When using a device with a grinding function, the mixing is carried out under conditions that do not significantly change the Blaine specific surface area of ​​the gypsum. Examples of such mixers or devices include a Nauta mixer, a pan mixer, a tilting mixer, and a ribbon mixer.

[0054] In the method for producing the hydraulic composition, other components may be mixed in addition to the alkaline activator, granulated blast furnace slag, and gypsum. The alkaline activator, granulated blast furnace slag, and other components may be ground into individual raw materials, and gypsum may be ground to have a Blaine specific surface area within the above-mentioned range. The timing of mixing the other components may be adjusted as appropriate, and is not limited as long as the mixing does not affect the Blaine specific surface area of ​​the gypsum. For example, the other components may be added and mixed simultaneously with the alkaline activator, granulated blast furnace slag, and gypsum, or may be mixed with the alkaline activator and granulated blast furnace slag. Alternatively, the other components may be added after the cement is prepared. Since the Blaine specific surface area of ​​the gypsum varies little, a method in which the other components are mixed with the alkaline activator and granulated blast furnace slag may be used.

[0055] Examples of other components include accelerators.

[0056] (accelerator) The accelerator is a compound that accelerates the reaction of granulated blast furnace slag and improves its early strength.

[0057] The accelerator may contain a monovalent anion or a salt having a monovalent anion. The monovalent anion may be, for example, at least one anion selected from the group consisting of nitrite ion, nitrate ion, chloride ion, formate ion, and acetate ion. For example, 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.

[0058] The accelerator may contain at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts. When the accelerator contains an alkali metal salt or an alkaline earth metal salt, the reactivity of the granulated blast furnace slag can be further improved.

[0059] The alkali metal may be, for example, sodium or potassium, and the alkaline earth metal may be, for example, magnesium or calcium. From the viewpoint of promoting hydrate formation and improving compressive strength, the alkaline earth metal preferably contains calcium, and more preferably is calcium. The accelerator may contain, for example, a calcium salt.

[0060] In the hydraulic composition according to the present disclosure, similar to conventional hydraulic compositions containing an alkaline activator such as cement clinker, alkaline activators such as calcium hydroxide (Ca(OH)2) eluted from the alkaline activator are thought to contribute to the initiation of the hardening reaction of granulated blast furnace slag. Similar to the alkaline activator, the accelerator is expected to further accelerate the hardening of granulated blast furnace slag by eluting components containing, for example, calcium. Therefore, when the accelerator contains a calcium salt, a more sufficient hardening reaction of granulated blast furnace slag can be expected even when the amount of alkaline activator is small. This effect allows for greater tolerance of fluctuations in the amounts of each component in the hydraulic composition, making the hydraulic composition according to the present disclosure easier to use.

[0061] 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.

[0062] The upper limit of the accelerator content may be, for example, 4.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, 1.0 parts by mass or less, or 0.8 parts by mass or less, relative to 100 parts by mass of the cement. By keeping the upper limit of the accelerator content within the above range, the occurrence of abnormal setting, which occurs 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 may be, for example, 0.2 parts by mass or more, 0.3 parts by mass or more, 0.4 parts by mass or more, 0.5 parts by mass or more, or 0.6 parts by mass or more, relative to 100 parts by mass of the cement. 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 accelerator content may be adjusted within the above range, and may be 0.2 to 4.0 parts by mass or 0.3 to 2.0 parts by mass, relative to 100 parts by mass of the cement.

[0063] 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.

[0064] One embodiment of the hydraulic composition includes cement made of an alkaline activator, granulated blast furnace slag, and gypsum. The SO3 equivalent value of the cement is 1.5 to 7.0 mass%. Based on a total of 100 mass% of the cement, the content of the alkaline activator is 10.0 to 50.0 mass%, the content of the granulated blast furnace slag is 45.0 to 75.0 mass%, and the content of the gypsum is 2.0 to 15.0 mass%, and the gypsum includes anhydrous gypsum. The Blaine specific surface area of ​​the gypsum is 1500 to 3500 cm. 2 / g.

[0065] [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. In other words, 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-described production method, a hardened mortar may be produced by mixing, in addition to water, fine aggregate, coarse aggregate, admixtures, etc. In the above-described method for producing a hardened product, the hardening time may be about 24 hours, but it is preferable to ensure a relatively long time. The hardening time may be, for example, 48 hours or more, 72 hours or more. During the hardening process, it is preferable to maintain the mortar or the like in a molded state, for example, in a formwork, so as to maintain the shape of the desired hardened product.

[0066] The hydraulic composition may be produced by the same method as the hydraulic composition described above. That is, one embodiment of the method for producing a hardened body is a method for producing a hardened body by mixing an alkali activator, granulated blast furnace slag, and a clayey ... 2 / g of gypsum to prepare cement, and blending 50 parts by mass of water with 100 parts by mass of a hydraulic composition containing the cement. The SO3 equivalent value of the cement is 1.5 to 7.0% by mass. Based on a total of 100% by mass of the cement, the content of the alkali activator is 10.0 to 50.0% by mass, the content of the granulated blast furnace slag is 45.0 to 75.0% by mass, the content of the gypsum is 2.0 to 15.0% by mass, and the gypsum includes anhydrous gypsum. The Blaine specific surface area of ​​the gypsum is 1500 to 3500 cm 2 / g.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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]

[0073] 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.

[0074] [Raw materials for hydraulic compositions] The following materials were used as raw materials for the hydraulic composition.

[0075] (Alkaline stimulant) Cement clinker was used as the alkali activator. The cement clinker used is the cement clinker commonly used when preparing ordinary Portland cement. In Table 1, ordinary Portland cement clinker is abbreviated as "OPC." The chemical composition of the cement clinker was measured in accordance with the description in JIS R 5202:2015 "Methods for chemical analysis of cement." The results are shown in Table 1.

[0076] (granulated blast furnace slag) The granulated blast furnace slag used was ground granulated blast furnace slag without gypsum addition and ground granulated blast furnace slag with gypsum addition. In Table 1, the ground granulated blast furnace slag without gypsum addition is designated "BFS1," and the ground granulated blast furnace slag with gypsum addition is designated "BFS2." 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.

[0077] (plaster) The gypsum used was natural anhydrous gypsum, which was ground in a ball mill to a specified Blaine value to adjust the Blaine specific surface area. In Table 1, the Blaine specific surface area was 2290 cm 2 / g of anhydrous gypsum is referred to as "gypsum 1", and the Blaine specific surface area is 4300 cm 2 / g of anhydrous gypsum is referred to as "gypsum 2", and the Blaine specific surface area is 6300 cm 2 / g of anhydrous gypsum is referred to as "gypsum 3." The Blaine specific surface area of ​​the gypsum was measured in accordance with the method described in JIS R 5201:2015 "Physical test methods for cement." The chemical composition of the gypsum was measured in accordance with the method described in JIS R 5202:2015 "Chemical analysis methods for cement." The results are shown in Table 1.

[0078] [Table 1]

[0079] (accelerator) An inorganic accelerator, calcium nitrite monohydrate manufactured by Kishida Chemical Co., Ltd., was used as the accelerator.

[0080] [Example 1] As an alkaline stimulant, 30% by mass of ordinary Portland cement clinker was used, 66% by mass of granulated blast furnace slag powder without gypsum was used as granulated blast furnace slag, and the gypsum specified in the present disclosure had a Blaine specific surface area of ​​2290 cm 2 Each component was weighed out so that the anhydrous gypsum (Sb / g) would be 2.2% by mass, and the components were mixed by hand in a bag for 5 minutes to prepare cement. The amount of SO3 in the cement was 1.9% by mass.

[0081] Next, calcium nitrite monohydrate was measured out as an accelerator so that the accelerator was 2 parts by mass per 100 parts by mass of the cement, kneaded, dissolved in water and mixed to prepare a hydraulic composition.

[0082] [Examples 2 to 3, Comparative Examples 1 to 9] Hydraulic compositions were prepared in the same manner as in Example 1, except that the components and blending amounts were changed as shown in Table 2.

[0083] [Table 2]

[0084] <Evaluation of properties of hydraulic composition> The chemical composition, ignition loss, and Blaine specific surface area were measured for each of the hydraulic compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 9. The chemical composition was measured in accordance with the description in JIS R 5202:2015, "Methods for chemical analysis of cement." The ignition loss (also abbreviated as ig.loss) was 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. Methods for determining ignition loss" of JIS R 5202:2010. The Blaine specific surface area was measured in accordance with the method described in JIS R 5201:2015, "Physical testing methods for cement." The results are shown in Table 3.

[0085] [Table 3]

[0086] <Evaluation of hydraulic composition: compressive strength> The compressive strength of each of the hydraulic compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 9 was measured at ages of 3 days, 7 days, and 28 days according to the method described below. The results are shown in Table 4.

[0087] 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").

[0088] 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 according to the description in 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 hardened mortar at 3 days of age. Similarly, the obtained hardened mortar was cured in water for 7 days (7-day age) and 28 days (28-day age) in a thermostatic chamber at 20°C, and the compressive strength of the hardened mortar at 7 days of age and 28 days of age was measured. The compressive strength was measured in accordance with the description of JIS R 5201:1992 "Physical testing methods for cement."

[0089] [Table 4] [Industrial Applicability]

[0090] According to the present disclosure, it is possible to provide a method for producing a hydraulic composition that can produce a hardened product that has excellent compressive strength from the early stage to the long term, and the hydraulic composition.

Claims

1. Alkaline stimulant, granulated blast furnace slag, and blaine with a specific surface area of ​​1500 to 3500 cm ２ / g of gypsum to prepare cement; SO detected by X-ray fluorescence analysis of the cement ３ The content of is 1.5 to 7.0 mass% based on the total amount of the cement, Based on 100% by mass of the total of the cement, The content of the alkaline irritant is 10.0 to 50.0% by mass, The content of the granulated blast furnace slag is 45.0 to 75.0 mass%, The gypsum content is 2.0 to 15.0% by mass. A method for producing a hydraulic composition.

2. The method of claim 1, further comprising mixing 0.2 to 4.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement.

3. The cement comprises an alkaline irritant, granulated blast furnace slag, and gypsum; SO detected by X-ray fluorescence analysis of the cement ３ The content is 1.5 to 7.0 mass %, Based on 100% by mass of the total of the cement, The content of the alkaline irritant is 10.0 to 50.0% by mass, The content of the granulated blast furnace slag is 45.0 to 75.0 mass%, The gypsum content is 2.0 to 15.0% by mass, the gypsum includes anhydrite; The Blaine specific surface area of ​​the gypsum is 1500 to 3500 cm ２ / g of the hydraulic composition.

4. further comprising an accelerator; 4. The hydraulic composition according to claim 3, wherein the content of the accelerator is 0.2 to 4.0 parts by mass per 100 parts by mass of the cement.

5. The hydraulic composition according to claim 4, wherein the accelerator contains at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts.

6. 6. The hydraulic composition according to claim 4, wherein the accelerator is a salt having a monovalent anion.

7. The hydraulic composition according to claim 3 or 4, wherein the alkaline activator contains at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime.

8. 5. The hydraulic composition according to claim 3, wherein the basicity of the granulated blast furnace slag is 1.60 to 1.

95.

9. The hydraulic composition according to claim 3 or 4, wherein the content of aluminum oxide in the granulated blast furnace slag is 10.0 mass% or more.

Images