Hydraulic composition, method for producing hydraulic composition, and method for increasing compressive strength of hydraulic composition

Abstract

To provide a hydraulic composition, in which a mixing ratio of granulated blast furnace slag and carbonate, etc. is increased and the ratio of alkaline stimulant is decreased, capable of reducing the amount of CO2 generated in manufacturing and also exhibiting an excellent compressive strength both initially and for a long period of time.SOLUTION: According to one aspect of the hydraulic composition according to the present disclosure that includes cement containing an alkaline stimulant, granulated blast furnace slag and carbonate, and an accelerating admixture, based on a total amount of the cement, the content of the alkaline stimulant is 5.0 to 60.0 mass%, the content of the granulated blast furnace slag is 35.0 to 90.0 mass%, the content of the carbonate is 5 to 40 mass%, the content of gypsum in the cement is 1.70 mass% or less in SO3 conversion, and the content of the accelerating admixture is 0.2 to 5.0 pts.mass with respect to 100 pts.mass of the cement.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to hydraulic compositions, methods for making hydraulic compositions, and methods for increasing the compressive strength of hydraulic compositions. [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 the production of hydraulic compositions containing cement. To reduce CO2 emissions, a method of producing hydraulic compositions by replacing part of the cement clinker, which generates a large amount of CO2 during preparation, with admixtures has been widely studied. Among admixtures, steel slag, such as granulated blast furnace slag (BFS), is expected to increase the long-term strength of concrete and improve its salt-shielding effect. Therefore, research is being conducted on cement that uses steel slag as an admixture and increases its mixing ratio.

[0003] However, blast furnace slag cement with a higher mixing ratio tends to have lower initial strength when hardening compared to cement made with ordinary Portland cement (OPC) alone. Therefore, various methods are being investigated to achieve the same level of strength as cement made with OPC alone, even in the case of blast furnace slag cement.

[0004] For example, methods that have been reported include further adding calcium hydroxide fine powder (e.g., Non-Patent Document 1), and producing blast-furnace cement using Portland cement clinker with a high C3S content (e.g., Non-Patent Document 2).In addition, the use of inorganic or organic accelerators other than calcium hydroxide fine powder has also been investigated as a measure to improve the early strength of cement compositions.

[0005] Furthermore, in blast furnace cement containing a high proportion of granulated blast furnace slag, etc., gypsum is incorporated to improve early strength (e.g., Non-Patent Document 3). Aiming to achieve strength comparable to that achieved when OPC is used alone, the amount of gypsum is increased, and further studies are being conducted to improve early strength by incorporating an accelerator that accelerates the hardening reaction of cement clinker (e.g., Patent Document 1). Furthermore, Patent Document 2 discloses that in low-carbon concrete that does not contain an accelerator, blast furnace slag powder with gypsum added internally has superior quality stability.

[0006] It has been confirmed that the hydration reaction of ground granulated blast furnace slag in blast furnace cement mixed with granulated blast furnace slag is activated by the use of nitrite.Patent Document 3 discloses a cementitious hydraulic composition in which part of the cement is replaced with ground granulated blast furnace slag having latent hydraulic properties as a cement substitute, and in which nitrite is added to activate the hydration reaction of the ground granulated blast furnace slag.

[0007] Furthermore, Non-Patent Document 4 discloses a technology for reducing the cement clinker content and reducing carbon dioxide emissions resulting from the production of cement clinker by replacing part of blast furnace cement type B with limestone fine powder (fine powder of calcium carbonate).

[0008] There is a movement to fix carbon dioxide emitted from exhaust gases from coal-fired power plants, cement kilns, and the like with Ca or Mg and effectively utilize the resulting carbonates. One possible use for this is resin fillers, for example. However, the amount available for use as a resin filler is small. Therefore, applications that allow for the use of large amounts of the carbonates described above are being considered. It would be effective if the carbonates described above could be used as components to be blended into hydraulic compositions, which are raw materials for concrete and the like. However, it cannot be said that methods for using the carbonates described above as components to be blended into hydraulic compositions have been fully explored. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-125371 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-141614 [Patent Document 3] Japanese Patent Application Publication No. 2018-076203 [Non-patent literature]

[0010] [Non-Patent Document 1] Hiroaki Yoshiga et al., "Effect of Fine Calcium Hydroxide Powder on Cement Containing Blast Furnace Slag," Cement & Concrete Journal, Vol. 67, 2013, pp. 151-156 [Non-patent document 2] Atsushi Yatagai et al., "Effect of Specific Surface Area of ​​Ground Blast Furnace Slag on the Properties of Blast Furnace Cement Using High C3S Clinker," Proceedings of the Cement and Concrete Society, Vol. 67, 2013, pp. 296-303 [Non-patent document 3] Etsuro Sakai et al., "Effect of calcium nitrite and alkanolamines on the hydration of high-blast furnace slag cement," Proceedings of the Cement and Concrete Journal, 2019, Vol. 73, pp. 52-57 [Non-patent document 4] Toyokazu Nishida et al., "Development of Environmentally Friendly Blended Cement Using Limestone Powder," Proceedings of the Cement and Concrete Journal, Vol. 66, 2012, pp. 375-381 Summary of the Invention [Problem to be solved by the invention]

[0011] In blast furnace cement containing a high proportion of granulated blast furnace slag, etc., even when gypsum and an accelerator are used in combination as described above, the expected improvement in early strength due to the addition of an accelerator may not be achieved in some cases. For example, when blast furnace cement prepared with the accelerator is hardened, the early strength is improved compared to when the accelerator is not added, but the strength may not be as expected or may decrease as the material ages.

[0012] Furthermore, it is known that hydraulic compositions containing carbonates generally suffer from a problem of reduced compressive strength. Although there are not many known examples of carbonates being blended into cement containing a large amount of granulated blast furnace slag as described above, based on the findings of the present inventors, it is assumed that blending carbonates will further impair the strength development of the hydraulic composition.

[0013] The present disclosure aims to provide a hydraulic composition that can reduce CO2 emissions during production and exhibit excellent compressive strength both in the early and long term, and a method for producing the same, in which the mixing ratio of granulated blast furnace slag and carbonates, etc. is increased and the ratio of alkaline activators is decreased. The present disclosure also aims to provide a method for improving the compressive strength, both in the early and long term, of a hydraulic composition that has a high mixing ratio of granulated blast furnace slag, etc. [Means for solving the problem]

[0014] The inventors have investigated the above-mentioned problems and found that, when increasing the amount of gypsum and adding an accelerator, both of which are considered to be beneficial for improving early strength, are used in combination, the gypsum can inhibit the action of the accelerator, and that this inhibiting action can affect accelerators in general and strongly affect alkaline earth metal nitrites intended to accelerate the hardening of granulated blast furnace slag. Furthermore, the inventors have found that when an accelerator is added and the amount of gypsum is increased in accordance with conventional technical common sense in order to compensate for the expected decrease in strength development of a hydraulic composition due to the addition of a carbonate to granulated blast furnace slag, not only does this not compensate for the decrease in strength development due to the carbonate, but the gypsum also inhibits the action of the accelerator, which can actually accelerate the decrease in strength development of the hydraulic composition.

[0015] A more detailed explanation follows. First, gypsum in the hydraulic composition is a component that controls the reactivity of the alkaline activator and adjusts the hydration reaction of the hydraulic composition. However, it also reacts with components (e.g., Ca, Al) contained in granulated blast furnace slag to form ettringite (3CaO·Al2O3·3CaSO4·32H2O), which has low solubility. This ettringite covers the particle surfaces of the granulated blast furnace slag, inhibiting its dissolution and slowing the reaction rate. In particular, in the case of a hydraulic composition containing an accelerator, the accelerator not only promotes the dissolution and reaction of the granulated blast furnace slag in the early stages of the reaction, but also promotes the formation of ettringite through a reaction with the large amount of gypsum present in the same system. In other words, compared to a case in which an accelerator is not included, the reaction for ettringite formation as described above is promoted, and the excessive amount of ettringite produced can actually inhibit the reaction of the granulated blast furnace slag. Here, it is generally believed that increasing the amount of gypsum blended is beneficial for increasing strength, since the formation of ettringite increases bound water and can reduce voids at the initial stage of the hardening reaction. However, it was discovered that the amount of gypsum blended can actually have a negative effect when used in combination with an accelerator. Therefore, it was newly discovered that in systems where gypsum and an accelerator are used in combination, by reducing the gypsum content, contrary to conventional technical common sense, the resulting hydraulic composition can exhibit excellent compressive strength both in the early stages and over the long term.

[0016] The decrease in strength development due to the addition of carbonates is caused by a decrease in the proportion of the alkali activator in cement, which contributes most to strength development, and by the aluminum eluted from granulated blast furnace slag reacting with carbonates to form low-solubility carbonate hydrates (e.g., 3CaO·Al2O3·CaCO3·11H2O), which coat the particle surfaces of the granulated blast furnace slag, inhibiting its dissolution and slowing its long-term reactivity. When carbonates are present in large amounts, not only does the reaction between gypsum and granulated blast furnace slag produce excessive amounts of ettringite, but the additional production of carbonate hydrates can significantly inhibit the hardening reaction of granulated blast furnace slag. Furthermore, in hydraulic compositions that use carbonate in addition to granulated blast furnace slag from the viewpoint of further reducing the amount of CO2 generated during production, the strength development of the hydraulic composition may be further reduced, and therefore, in order to suppress the reduction in strength development, it has been newly discovered that it is more important to reduce the gypsum content, contrary to the conventional common technical knowledge that increasing the amount of gypsum blended is effective in improving the strength development of the hydraulic composition. The present disclosure has been made based on these new findings.

[0017] One aspect of the present disclosure provides a hydraulic composition comprising: cement containing an alkaline activator, granulated blast furnace slag, and a carbonate; and an accelerator, wherein, based on the total amount of the cement, the content of the alkaline activator is 5.0 to 60.0 mass%, the content of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%, the content of gypsum in the cement is 1.70 mass% or less in terms of SO3, and the content of the accelerator is 0.2 to 5.0 parts by mass per 100 parts by mass of the cement.

[0018] The hydraulic composition contains a predetermined amount of carbonate in addition to granulated blast furnace slag, which makes it possible to further reduce the amount of CO2 generated during the production of the hydraulic composition. Also, by keeping the gypsum content low and using a predetermined amount of accelerator in combination, the hydraulic composition can suppress the influence of gypsum, which inhibits the hardening-accelerating effect of the accelerator, and can exhibit excellent compressive strength both in the early stages and over the long term, despite having a relatively high content of granulated blast furnace slag and carbonate and a low content of alkaline activator.

[0019] The carbonate may include at least one selected from the group consisting of alkali metal carbonates and alkaline earth metal carbonates.

[0020] The carbonate may include at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

[0021] The total content of the granulated blast furnace slag and the carbonate, and the content of the gypsum may satisfy the relationship of the following formula (1): By adjusting the content of the granulated blast furnace slag, the content of the carbonate, and the content of the gypsum so as to satisfy the relationship of the following formula (1), it is possible to achieve a higher level of both initial and long-term compressive strength. [Gypsum content]≦1.5−2.0([Total content of granulated blast furnace slag and carbonate]−60) / 100…Equation (1)

[0022] The accelerator may be at least one selected from the group consisting of nitrites, nitrates, and chlorides. When the accelerator contains the accelerator, the hydraulic composition has better initial compressive strength when hardened.

[0023] The accelerator may contain a salt having a monovalent anion, which adjusts the formation of hydrates on the surface of the granulated blast furnace slag and further improves the reactivity of the granulated blast furnace slag.

[0024] The accelerator may contain a calcium salt. When the accelerator contains a calcium salt, calcium ions (Ca 2+ ) concentration and promote the production of calcium silicate hydrate (CSH), which is the main component of the hardened body, resulting in better early compressive strength.

[0025] 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.

[0026] 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.

[0027] The gypsum may contain at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate. The inclusion of at least one of gypsum dihydrate and gypsum hemihydrate in the gypsum can further promote the initial reaction between the alkaline activator (e.g., Portland cement clinker) and granulated blast furnace slag. While gypsum can be any of gypsum anhydrite, gypsum dihydrate, and gypsum hemihydrate, the reason why the above-mentioned effect is significant when the hydraulic composition according to the present disclosure contains at least one of gypsum dihydrate and gypsum hemihydrate is believed to be due to the following reason. That is, gypsum dihydrate and gypsum hemihydrate have a faster dissolution rate than gypsum anhydrite and can contribute to the reaction between the alkaline activator and granulated blast furnace slag at an earlier stage of the hardening reaction. Therefore, the effect can be significantly achieved when at least one of gypsum dihydrate and gypsum hemihydrate is contained. The above-mentioned difference is particularly evident in a system with a reduced gypsum content, such as the hydraulic composition according to the present disclosure.

[0028] The basicity of the granulated blast furnace slag may be less than 1.75. Since the hydraulic composition can fully utilize the effect of the accelerator by reducing the gypsum content, it is possible to use granulated blast furnace slag, so-called low-grade slag, which is generally not used in order to improve early strength. The hydraulic composition can use granulated blast furnace slag with a basicity of less than 1.75, which can be classified as low-grade slag, and even in this case, it can exhibit excellent compressive strength both in the early stages and over the long term.

[0029] The basicity of the granulated blast furnace slag may be 1.75 to 1.95. When the basicity 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, making it possible to produce concrete with excellent strength development. It is generally known that a low basicity reduces the reactivity and strength development performance of granulated blast furnace slag. However, in the hydraulic composition according to the present disclosure, even when granulated blast furnace slag with a low basicity is used, by adjusting the basicity to fall within the above range, it is possible to obtain a hydraulic composition that can exhibit even better strength development performance.

[0030] The aluminum oxide content of the granulated blast furnace slag may be 14.5% by mass or less. By using granulated blast furnace slag with a relatively low aluminum oxide content, the amount of ettringite that can inhibit the reaction of the granulated blast furnace slag can be further suppressed, and the reaction of the granulated blast furnace slag can be promoted over a longer period of time. Furthermore, by using granulated blast furnace slag with a relatively low aluminum oxide content, it is possible to reduce the amount of accelerator used, thereby further reducing the cost required for concrete production.

[0031] The content of the granulated blast furnace slag may be 35.0 to 70.0 mass% based on the total amount of the cement. Since the effect of the accelerator can be fully achieved by reducing the gypsum content in the hydraulic composition, even a composition containing a high amount of granulated blast furnace slag, which is generally not widely used from a practical standpoint, can exhibit compressive strength superior to that of conventional blast furnace cements.

[0032] One aspect of the present disclosure provides a method for producing a hydraulic composition, including: a first step of preparing cement by mixing raw materials containing an alkaline activator, granulated blast furnace slag, and carbonate so that the content of the alkaline activator is 5.0 to 60.0 mass%, the blending amount of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%; and a second step of mixing 0.2 to 5.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement, wherein in the first step, the content of gypsum in the cement is adjusted to 1.70 mass% or less in terms of SO3.

[0033] The above-mentioned manufacturing method includes a first step of blending granulated blast furnace slag in a relatively large amount, and a second step of further blending an accelerator. Since the gypsum content is also adjusted in the first step, the hydraulic composition as described above can be manufactured.

[0034] The carbonate may include at least one selected from the group consisting of alkali metal carbonates and alkaline earth metal carbonates.

[0035] The carbonate may include at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

[0036] In the first step, the gypsum may be blended so that the total content of the granulated blast furnace slag and the carbonate and the content of the gypsum satisfy the relationship of the following formula (1). [Gypsum content]≦1.5−2.0([Total content of granulated blast furnace slag and carbonate]−60) / 100…Equation (1)

[0037] One aspect of the present disclosure provides a method for increasing the compressive strength of a hydraulic composition, the method comprising: measuring a gypsum content in a composition containing cement that includes an alkaline activator, granulated blast furnace slag, and a carbonate, wherein the content of the alkaline activator is 5.0 to 60.0 mass%, the content of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%; and measuring a content of an accelerator in the composition and adjusting the content of the accelerator to 0.2 to 5.0 parts by mass per 100 parts by mass of the cement.

[0038] The method for increasing the compressive strength of a hydraulic composition described above involves adjusting the content of gypsum in the cement and the content of an accelerator in a composition containing a predetermined cement, thereby increasing the compressive strength of the resulting hydraulic composition during hardening.

[0039] The carbonate may include at least one selected from the group consisting of alkali metal carbonates and alkaline earth metal carbonates.

[0040] The carbonate may include at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

[0041] In the method for increasing compressive strength, the composition may contain an accelerator. When the composition already contains an accelerator, that is, when the composition is a hydraulic composition itself, the method for increasing compressive strength can be applied. [Effects of the Invention]

[0042] According to the present disclosure, it is possible to provide a hydraulic composition and a method for producing the same, which can further reduce the amount of CO2 generated during production and can exhibit excellent compressive strength both in the early and long term, in a hydraulic composition in which the mixing ratio of granulated blast furnace slag and carbonates, etc. is increased and the ratio of alkaline activators is decreased.The present disclosure also provides a method for improving the compressive strength, both in the early and long term, of a hydraulic composition in which the mixing ratio of granulated blast furnace slag, etc. is high. DETAILED DESCRIPTION OF THE INVENTION

[0043] 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.

[0044] 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.

[0045] [Hydraulic composition] One embodiment of the hydraulic composition includes cement containing an alkaline activator, granulated blast furnace slag, and a carbonate, and an accelerator. The content of the alkaline activator is 5.0 to 60.0 mass% based on the total amount of the cement. The content of the granulated blast furnace slag is 35.0 to 90.0 mass% based on the total amount of the cement. The content of the carbonate is 5 to 40 mass% based on the total amount of the cement. The content of gypsum in the cement is 1.70 mass% or less in terms of SO3. The content of the accelerator is 0.2 to 5.0 mass parts per 100 mass parts of the cement. In this specification, cement refers not only to cases where the alkaline activator contains Portland cement clinker, but also to a powder containing granulated blast furnace slag as a main component and containing an alkaline activator and a carbonate (and, in some cases, further containing gypsum). The cement may be composed of an alkaline activator, granulated blast furnace slag, and a carbonate. In this case, it means that the cement does not need to contain gypsum.

[0046] 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.

[0047] 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.

[0048] 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 ratio of the main minerals in Portland cement clinker from the content ratio of the chemical composition. 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 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".

[0049] <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 [%]

[0050] The amount of C3A in Portland cement clinker is preferably 0.5 to 11.0 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.

[0051] 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.

[0052] The content of the alkali activator is 5.0 to 60.0 mass% based on the total amount of the cement. When the content of the alkali activator is within the above range, the amount of CO2 generated during the production of the hydraulic composition can be sufficiently suppressed.

[0053] The lower limit of the content of the alkaline activator may be, for example, 7.0 mass% or more, 10.0 mass% or more, 15.0 mass% or more, 20.0 mass% or more, or 25.0 mass% or more, based on the total amount of the cement. When the lower limit of the content of the alkaline activator is within the above range, a decrease in strength development can be sufficiently suppressed. The upper limit of the content of the alkaline activator may be, for example, 55.0 mass% or less, 50.0 mass% or less, 45.0 mass% or less, 40.0 mass% or less, or 35.0 mass% or less, based on the total amount of the cement. When the upper limit of the content of the alkaline activator is within the above range, the amount of CO2 generated in the production of the hydraulic composition can be more significantly reduced. The content of the alkaline activator may be adjusted within the above range, and may be, for example, 7.0 to 50.0 mass%, 10.0 to 50.0 mass%, 10.0 to 40.0 mass%, 15.0 to 30.0 mass%, or 20.0 to 30.0 mass%, based on the total amount of the cement.

[0054] The granulated blast furnace slag may be, for example, commercially available, or slag equivalent to the granulated blast furnace slag may be prepared and used. The hydraulic composition according to the present disclosure can fully utilize the accelerator capabilities by adjusting the amount of gypsum in the cement, and therefore, regardless of the quality of the granulated blast furnace slag, can exhibit superior compressive strength upon hardening compared to conventional hydraulic compositions with a relatively high gypsum content.

[0055] The upper limit of the aluminum oxide content (Al2O3 content) in the granulated blast furnace slag may be, for example, 14.5% by mass or less, 14.0% by mass or less, 13.5% by mass or less, 13.0% by mass or less, or 12.5% ​​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 suppressed from decreasing. The lower limit of the Al2O3 content in the granulated blast furnace slag may be, for example, 8% by mass or more, 10% by mass or more, or 12% 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 Al2O3 content in the granulated blast furnace slag may be adjusted within the above range, for example, 8 to 14.5% by mass or 10 to 12.5% ​​by mass.

[0056] 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, 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 in the granulated blast furnace slag may be adjusted within the above range, for example, 34.5 to 40.0 mass%.

[0057] 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%.

[0058] 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, 7.0% by mass or more, or 7.2% by mass or more. When 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, or less than 7.4% by mass. When 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.

[0059] Granulated blast furnace slag may contain, as other components, for example, sulfur trioxide (SO3), sodium oxide (NaO2), potassium oxide (K2O), and titanium oxide (TiO2).

[0060] 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."

[0061] 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.

[0062] As the granulated blast furnace slag having a high basicity, for example, one having a basicity of 1.75 or more can be used. 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 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.

[0063] 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, even such low-grade slag can be used because it can suppress the inhibitory effect on the accelerator. Such low-grade granulated blast furnace slag may have an upper basicity limit of, 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, 1.55 or more, 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, 1.55 or more but less than 1.75.

[0064] 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).

[0065] 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.

[0066] 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."

[0067] The content of the granulated blast furnace slag is 40.0 to 90.0 mass% based on the total amount of the cement, which can contribute to reducing CO2 emissions during the production of the hydraulic composition. The hydraulic composition according to the present disclosure reduces the amount of gypsum in the cement and can exhibit a hardening acceleration effect by using an accelerator in combination, which can prevent a significant decrease in compressive strength and increase the proportion of granulated blast furnace slag substituted in the cement.

[0068] The lower limit of the content of granulated blast furnace slag may be, for example, 35.0 mass% or more, 40.0 mass% or more, 50.0 mass% or more, or 55.0 mass% or more, based on the total amount of the cement. When the lower limit of the content of granulated blast furnace slag is within the above range, the amount of alkaline activator used can be further reduced. The upper limit of the content of granulated blast furnace slag may be, for example, 90.0 mass% or less, 85.0 mass% or less, 80.0 mass% or less, 70.0 mass% or less, or 60.0 mass% or less, based on the total amount of the cement. When the upper limit of the content of granulated blast furnace slag is within the above range, the decrease in early strength can be further suppressed, and the effect of using an accelerator in combination can be further improved. The content of granulated blast furnace slag may be adjusted within the above range, and may be, for example, 35.0 to 90.0 mass%, 35.0 to 70.0 mass%, 40.0 to 70.0 mass%, or 40.0 to 60.0 mass% based on the total amount of the cement.

[0069] 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). 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 quantify gehlenite, merwinite, and the like as crystalline phases formed by crystallization of the granulated blast furnace slag. 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 blended amount (measured value) of granulated blast furnace slag added during the manufacturing process corresponds to the content.

[0070] The carbonate may include at least one selected from the group consisting of, for example, alkali metal carbonates and alkaline earth metal carbonates, and preferably includes an alkaline earth metal carbonate. Examples of the alkali metal carbonate include sodium carbonate. Examples of the alkaline earth metal carbonate include calcium carbonate and magnesium carbonate. When the carbonate includes an alkaline earth metal carbonate, it preferably includes calcium carbonate.

[0071] The carbonate content is 5 to 40% by mass, based on the total amount of the cement. If the carbonate content is less than 5% by mass, the effect of reducing CO2 emissions during the production of the hydraulic composition is insufficient, while if it exceeds 40% by mass, the effect of suppressing a decrease in the strength development of the hydraulic composition tends to be insufficient. The lower limit of the carbonate content may be, for example, 7% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total amount of the cement. When the lower limit of the carbonate content is within the above range, the amount of CO2 generated during the production of the hydraulic composition can be further reduced. The upper limit of the carbonate content may be, for example, 35% by mass or less, 30% by mass or less, or 25% by mass or less, based on the total amount of the cement. When the upper limit of the carbonate content is within the above range, a hydraulic composition with excellent strength development can be provided.

[0072] The carbonate content in this specification refers to a value determined by the following method. Specifically, the total carbon content in the cement composition is measured using a carbon / sulfur analyzer (C / S meter), and the resulting value is converted into the carbonate content using the following formula (A): [Carbonate content (mass%)] = 12 ÷ [Total carbon content (mass%)] × [Molecular weight of CaCO3] ... Equation (A)

[0073] In the hydraulic composition according to the present disclosure, the gypsum content in the cement is kept relatively low. The gypsum content in the cement is 1.70 mass% or less in terms of SO3. By keeping the gypsum content within this range, the effect of the gypsum on improving the compressive strength associated with the hardening of the hydraulic composition can be exhibited, while the action of the accelerator on inhibiting the effect of improving the compressive strength associated with the hardening of the hydraulic composition can be reduced.

[0074] The upper limit of the gypsum content in the cement, calculated as SO3, may be, for example, 1.6% by mass or less, 1.5% by mass or less, 1.4% by mass or less, 1.3% by mass or less, 1.2% by mass or less, 1.0% by mass or less, or 0.8% by mass or less. When the upper limit of the gypsum content is within the above range, the hydraulic composition containing the accelerator can exhibit better strength development. The lower limit of the gypsum content in the cement may be 0% by mass (i.e., no gypsum is contained), but may be, for example, 0% by mass or more, 0.10% by mass or more, 0.20% by mass or more, 0.30% by mass or more, 0.40% by mass or more, or 0.50% by mass or more, calculated as SO3. Setting the lower limit of the gypsum (SO3) content within the above range makes the hydration reaction of the cement more favorable, thereby improving the fluidity of the hydraulic composition after mixing with water and improving the early strength development. The gypsum content in the cement may be adjusted within the above range, for example, 0 to 1.5 mass%, 0 to 1.3 mass%, 0 to 0.8 mass%, 0.10 to 1.5 mass%, or 0.50 to 1.3 mass%.

[0075] 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."

[0076] The gypsum that can be used includes, for example, 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.

[0077] 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.

[0078] The accelerator is a compound that accelerates the reaction of granulated blast furnace slag and improves its early strength.

[0079] The accelerator may be 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.

[0080] 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 an alkaline earth metal salt can further improve the reactivity of the granulated blast furnace slag. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium and calcium. From the viewpoints of promoting hydrate formation and improving compressive strength, the alkaline earth metal preferably contains calcium, and more preferably is calcium.

[0081] The accelerator may include a salt with a monovalent anion and may include a calcium salt.

[0082] 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.

[0083] The upper limit of the accelerator content may be, for example, 5.0 parts by mass or less, 4.0 parts by mass or less, 3.5 parts by mass or less, or 3.3 parts by mass or less, per 100 parts by mass of the cement. By ensuring that the upper limit of the accelerator content is within the above range, the occurrence of abnormal setting, which may occur when the reaction of granulated blast furnace slag or the like is excessively accelerated, can be more reliably suppressed. The lower limit of the accelerator content may be, for example, 0.2 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, 2.0 parts by mass or more, or 2.5 parts by mass or more, per 100 parts by mass of the cement. By ensuring that the lower limit of the accelerator content is within the above range, the reaction of granulated blast furnace slag can be further accelerated. The accelerator content may be adjusted within the above range, and may be, for example, 0.2 to 5.0 parts by mass or 0.5 to 3.5 parts by mass, per 100 parts by mass of the cement.

[0084] In the hydraulic composition, the total content of the granulated blast furnace slag and the carbonate and the gypsum content may satisfy the relationship represented by the following general formula (X). In the general formula (X), the gypsum content is the gypsum content in the cement (unit: mass%), expressed as an SO3 equivalent value. In the general formula (X), the total content of the granulated blast furnace slag and the carbonate is the sum of the granulated blast furnace slag content (unit: mass%) and the carbonate content (unit: mass%), based on the total amount of cement. In the general formula (X), A is a constant, which may be, for example, 1.5 or less. When the total content of the granulated blast furnace slag and the carbonate and the gypsum content satisfy the relationship represented by the general formula (X), in which the constant A is a smaller value, the effects of the present disclosure can be more pronounced. For example, the constant A may be 1.5, 1.0, 0.8, or 0.6. For reference, the formula when the constant A is 1.5 is shown below (see formula (1)). [Gypsum content]≦A-2.0([Total content of granulated blast furnace slag and carbonate]-60) / 100...General formula (X) [Gypsum content]≦1.5−2.0([Total content of granulated blast furnace slag and carbonate]−60) / 100…Equation (1)

[0085] 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, inorganic minerals containing Si and Al, a water-reducing agent for concrete, and a retarder.

[0086] [Method for producing hydraulic composition] The hydraulic composition can be produced, for example, by the following method. One embodiment of a method for producing a hydraulic composition includes a first step of preparing cement by mixing raw materials containing an alkaline activator, granulated blast furnace slag, and carbonate so that the content of the alkaline activator is 5.0 to 60.0 mass%, the blending amount of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%, and a second step of mixing 0.2 to 5.0 mass parts of an accelerator per 100 mass parts of the cement. The first step also includes adjusting the content of gypsum in the cement to 1.70 mass% or less in terms of SO3.

[0087] The raw materials in the first step may be a mixture of an alkaline activator, granulated blast furnace slag, and carbonate, and may also contain gypsum.

[0088] 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.

[0089] In the first step, the gypsum content in the cement is adjusted to 1.70 mass% or less in terms of SO. This adjustment makes it possible to prevent gypsum from inhibiting the hardening-accelerating action of the accelerator in the hydraulic composition.

[0090] The gypsum content in the first step may be adjusted so that the total content of the granulated blast furnace slag and the carbonate and the gypsum content satisfy the relationship of the following general formula (X). In the following general formula (X), the gypsum content is the gypsum content in the cement (unit: mass%), expressed as an SO3 equivalent value. In the following general formula (X), the total content of the granulated blast furnace slag and the carbonate is the sum of the granulated blast furnace slag content (unit: mass%) and the carbonate content (unit: mass%), based on the total amount of cement. In the following general formula (X), A is a constant, which may be, for example, 1.5 or less. When the total content of the granulated blast furnace slag and the carbonate and the gypsum content satisfy the relationship of general formula (X), in which the constant A is a smaller value, the effects of the present disclosure can be more pronounced. For example, the constant A may be 1.5, 1.0, 0.8, or 0.6. For reference, the formula when the constant A is 1.5 is shown below (see formula (1)). [Gypsum content]≦A-2.0([Total content of granulated blast furnace slag and carbonate]-60) / 100...General formula (X) [Gypsum content]≦1.5−2.0([Total content of granulated blast furnace slag and carbonate]−60) / 100…Equation (1)

[0091] 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.

[0092] The hydraulic composition produced by the above-mentioned production method may be mixed with, for example, fine aggregate, coarse aggregate, water, admixtures, etc., and used as mortar.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] [Method for increasing the compressive strength of hydraulic compositions] By applying the above findings, a method for increasing the compressive strength of a composition containing a high proportion of granulated blast furnace slag or the like can be provided. The hydraulic composition obtained by applying this method can exhibit excellent compressive strength both initially and over the long term. One embodiment of the method for increasing the compressive strength of a hydraulic composition includes measuring the gypsum content of a composition containing cement, the composition including an alkaline activator, granulated blast furnace slag, and carbonate, the content of the alkaline activator being 5.0 to 60.0 mass%, the content of the granulated blast furnace slag being 35.0 to 90.0 mass%, and the content of the carbonate being 5 to 40 mass%, and adjusting the gypsum content of the cement to 0.05 to 1.70 mass% in terms of SO3, and measuring the content of an accelerator in the composition and adjusting the content of the accelerator to 0.2 to 5.0 mass parts per 100 mass parts of the cement.

[0099] Since the content of the accelerator is adjusted in the compressive strength increasing method, the composition may be accelerator-free or may contain an accelerator.

[0100] 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]

[0101] 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.

[0102] [Raw materials for hydraulic compositions] The following materials were used as raw materials for the hydraulic composition.

[0103] (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.

[0104] (plaster) The gypsum used was dehydrated gypsum, a by-product of coal-fired power plants, and reagent anhydrous gypsum. 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.

[0105] (granulated blast furnace slag) Slags A to D prepared according to the following method were used as granulated blast furnace slag. First, molten slag discharged from an actual blast furnace was water-cooled for the granulated blast furnace slag. Granulated blast furnace slag with different chemical compositions was sampled and then dried at 105°C to obtain slags A to D. Slag D was prepared by adding gypsum dihydrate to slag B and grinding and mixing it.

[0106] The chemical composition of the resulting slags A to D was measured in accordance with JIS R 5202:2015 "Methods for Chemical Analysis of Cement," and the crystalline phase was evaluated by X-ray diffraction. Aluminum oxide was used as the standard material for the evaluation of the crystalline phase by X-ray diffraction. Since no crystalline phase was detected in the resulting slags A to D and the vitrification rate was nearly 100%, it was confirmed that all of the slags were equivalent to commonly available granulated blast furnace slag. The measured chemical compositions of each of the slags A to D are shown in Table 1.

[0107] [Table 1]

[0108] 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.

[0109] (accelerator) An inorganic accelerator, calcium nitrite monohydrate (hereinafter sometimes referred to as CN) manufactured by Kishida Chemical Co., Ltd., was used.

[0110] [Example 1] The cement was prepared by mixing 30% by mass of cement clinker and gypsum, 55% by mass of granulated blast furnace slag (Slag B), and 15% by mass of limestone (calcium carbonate). The gypsum content in the cement was 0.59% by mass in terms of SO3.

[0111] Next, calcium nitrite monohydrate was mixed as an accelerator so that the amount of accelerator was 2 parts by mass, calculated as an anhydride, per 100 parts by mass of the cement, thereby preparing the hydraulic composition of Example 1.

[0112] [Example 2] Hydraulic compositions were prepared in the same manner as in Example 1, except that the amount of the accelerator was changed as shown in Table 2.

[0113] [Example 3] A hydraulic composition was prepared in the same manner as in Example 1, except that cement clinker containing a gypsum component was used instead of the mixture of cement clinker and gypsum. The gypsum content in the cement was 0.14 mass% in terms of SO3.

[0114] [Comparative Example 1] A hydraulic composition was prepared in the same manner as in Example 1, except that no accelerator was added.

[0115] Comparative Example 2 Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending ratio of the cement clinker and gypsum mixture was changed as shown in Table 2 and no accelerator was blended.

[0116] Comparative Example 3 Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending ratio of the cement clinker and gypsum in the mixture and the blending amount of the accelerator were changed as shown in Table 2.

[0117] Comparative Example 4 Hydraulic compositions were prepared in the same manner as in Example 4, except that the blending ratio of the cement clinker and gypsum mixture was changed as shown in Table 2 and no accelerator was blended.

[0118] Comparative Example 5 Hydraulic compositions were prepared in the same manner as in Example 1, except that the blending ratio of the cement clinker and gypsum in the mixture and the blending amount of the accelerator were changed as shown in Table 2.

[0119] [Reference example 1] As an example of conventional blast furnace cement without carbonate or accelerator, cement was prepared by measuring and mixing a mixture of cement clinker and gypsum at 30% by mass and granulated blast furnace slag (Slag B) at 70% by mass. The gypsum content in the cement was 1.94 in SO3 equivalent.

[0120] [Table 2]

[0121] In Table 2, the gypsum content refers not only to the amount of gypsum blended alone, but also to the amount including components in Portland cement clinker (alkali activator) and granulated blast furnace slag. For example, in Example 3, a hydraulic composition was prepared using cement that did not contain gypsum, and the value listed as the gypsum content in Table 2 refers to the content of gypsum-equivalent components derived from Portland cement clinker and granulated blast furnace slag.

[0122] [Evaluation of hydraulic composition: compressive strength] The hydraulic compositions prepared as described above were subjected to measurement and evaluation of compressive strength according to the method described below, and the compressive strength ratio was calculated based on the compressive strength of a comparative hydraulic composition containing no accelerator in systems using various granulated blast furnace slags. The results are shown in Table 3.

[0123] 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").

[0124] 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 measurement results were evaluated according to the following criteria, and the results are shown in Table 3. <Evaluation criteria for 28-day compressive strength> A: Compression strength is 50.0N / mm 2 That's all. B: Compression strength is 46.0N / mm 2 More than 50.0N / mm 2 is less than. C: Compression strength is 46.0N / mm 2 is less than. <Evaluation criteria for compressive strength ratio> A: The compressive strength ratio is 105% or more. B: The compressive strength ratio is 103% or more and less than 105%. C: The compressive strength ratio is 100% or more and less than 103%. D: The compressive strength ratio is less than 100%.

[0125] [Evaluation of hydraulic composition: calorific value of hydration] The hydraulic compositions prepared as described above were subjected to measurement of the heat generated by hydration according to the method described below. The results are shown in Table 3.

[0126] Specifically, for each of the hydraulic compositions prepared in the Examples, Comparative Examples, and Reference Examples, an evaluation sample was prepared by blending 40 parts by mass of water with 100 parts by mass of the hydraulic composition, and the integrated calorific value over three days from the start of measurement was measured using a hydration heat release rate measuring device (a conduction calorimeter manufactured by Tokyo Riko Co., Ltd.), and this was taken as the calorific value of hydration of the hydraulic composition to be measured.

[0127] [Table 3] [Industrial Applicability]

[0128] According to the present disclosure, it is possible to provide a hydraulic composition and a method for producing the same, which can further reduce the amount of CO2 generated during production and can exhibit excellent compressive strength both in the early and long term, in a hydraulic composition in which the mixing ratio of granulated blast furnace slag and carbonates, etc. is increased and the ratio of alkaline activators is decreased.The present disclosure also provides a method for improving the compressive strength, both in the early and long term, of a hydraulic composition in which the mixing ratio of granulated blast furnace slag, etc. is high.

Claims

1. Cement containing an alkaline irritant, granulated blast furnace slag, and carbonate; a promoter; Based on the total amount of the cement, the content of the alkali activator is 5.0 to 60.0 mass%, the content of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%, The gypsum content of the cement is ３ In terms of carbon content, this is 1.70% by mass or less, The content of the accelerator is 0.2 to 5.0 parts by mass per 100 parts by mass of the cement, The hydraulic composition, wherein the gypsum contains at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate.

2. 2. The hydraulic composition according to claim 1, wherein the carbonate comprises at least one selected from the group consisting of carbonates of alkali metals and carbonates of alkaline earth metals.

3. The hydraulic composition according to claim 1 or 2, wherein the carbonate comprises at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

4. The total content of the granulated blast furnace slag and the carbonate and the content of the gypsum satisfy the relationship of the following formula (1): [Gypsum content]≦1.5−2.0([total content of granulated blast furnace slag and carbonate]−60) / 100...Equation (1) The hydraulic composition according to any one of claims 1 to 3.

5. The hydraulic composition according to any one of claims 1 to 4, wherein the accelerator is at least one selected from the group consisting of nitrites, nitrates, and chlorides.

6. The hydraulic composition of claim 5, wherein the accelerator comprises a salt having a monovalent anion.

7. The hydraulic composition according to claim 5 or 6, wherein the accelerator contains at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts.

8. The hydraulic composition according to any one of claims 5 to 7, wherein the accelerator contains a calcium salt.

9. The hydraulic composition according to any one of claims 1 to 8, wherein the alkaline activator contains at least one selected from the group consisting of Portland cement clinker, slaked lime, and quicklime.

10. The hydraulic composition according to any one of claims 1 to 9, wherein the granulated blast furnace slag has a basicity of less than 1.

75.

11. The hydraulic composition according to any one of claims 1 to 9, wherein the basicity of the granulated blast furnace slag is 1.75 to 1.

95.

12. The hydraulic composition according to any one of claims 1 to 11, wherein the content of aluminum oxide in the granulated blast furnace slag is 14.5 mass% or less.

13. The hydraulic composition according to any one of claims 1 to 12, wherein the content of the granulated blast furnace slag is 35.0 to 70.0 mass% based on the total amount of the cement.

14. a first step of preparing cement by mixing raw materials including an alkaline activator, granulated blast furnace slag, and carbonates so that the content of the alkaline activator is 5.0 to 60.0 mass%, the blending amount of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonates is 5 to 40 mass%; A second step of mixing 0.2 to 5.0 parts by mass of an accelerator with respect to 100 parts by mass of the cement, In the first step, the content of gypsum in the cement is reduced by SO ３ The amount of SiO2 in the carbon dioxide gas is adjusted to 1.70% by mass or less in terms of carbon dioxide equivalent, The method for producing a hydraulic composition, wherein the gypsum contains at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate.

15. The method according to claim 14, wherein the carbonate comprises at least one selected from the group consisting of alkali metal carbonates and alkaline earth metal carbonates.

16. The method according to claim 14 or 15, wherein the carbonate comprises at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

17. In the first step, the gypsum is blended so that the total content of the granulated blast furnace slag and the carbonate and the content of the gypsum satisfy the relationship of the following formula (1): [Gypsum content]≦1.5−2.0([total content of granulated blast furnace slag and carbonate]−60) / 100...Equation (1) The method according to any one of claims 14 to 16.

18. A composition containing an alkaline activator, granulated blast furnace slag, and a carbonate, wherein the content of the alkaline activator is 5.0 to 60.0 mass%, the content of the granulated blast furnace slag is 35.0 to 90.0 mass%, and the content of the carbonate is 5 to 40 mass%. The content of gypsum in the cement is measured, and the content of gypsum in the cement is calculated by measuring the content of gypsum in the composition using SO ３ Adjusting the content to be 1.70 mass% or less in terms of carbon content; and measuring the content of the accelerator in the composition and adjusting the content of the accelerator to 0.2 to 5.0 parts by mass per 100 parts by mass of the cement; The method for increasing the compressive strength of a hydraulic composition, wherein the gypsum contains at least one selected from the group consisting of gypsum dihydrate and gypsum hemihydrate.

19. 20. The method of claim 18, wherein the carbonate comprises at least one selected from the group consisting of an alkali metal carbonate and an alkaline earth metal carbonate.

20. 20. The method of claim 18 or 19, wherein the carbonate comprises at least one selected from the group consisting of sodium carbonate, calcium carbonate, and magnesium carbonate.

21. The method of any one of claims 18 to 20, wherein the composition comprises an accelerator.

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