hydraulic components

Abstract

This invention provides a geopolymer-type hydraulic composition with excellent fluidity and hardened strength. [Solution] A hydraulic composition containing (A) fine aggregate, (B) metasilicate [hereinafter referred to as component (B)], (C) alumina silica fine powder, (D) bicarbonate [hereinafter referred to as component (D)], and (E) water, wherein the content of component (D) is 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B).

Description

Technical Field

[0001] The present invention relates to a hydraulic composition and a method for producing a hardened body.

Background Art

[0002] In recent years, for the realization of SDGs, infrastructure development considering the environment from the ESG perspective has been aimed at, and technological development of an environmentally friendly hydraulic composition with reduced cement that emits CO2 during the calcination of calcium carbonate has been progressing.

[0003] As an example, a hydraulic composition called geopolymers, which is obtained by curing blast furnace slag fine powder containing silicates such as aluminum silicate using an alkaline solution, has attracted attention.

[0004] Geopolymers harden by the dissolution of aluminum silicate in alkali and the formation of hydration products. Therefore, the more a strongly basic alkali stimulant such as sodium hydroxide or potassium hydroxide is used in combination, the better the strength development property is shown.

[0005] Patent Document 1 discloses the use of a mixture of sodium silicate and sodium carbonate as a curing accelerator for geopolymers using alumina-silica fine powder.

[0006] Patent Document 2 discloses a bicarbonate-based curing agent in a silicate-based soil stabilizing chemical solution containing, in a predetermined ratio, a component a: sodium bicarbonate, a component b: potassium bicarbonate, a component c: at least one selected from the group consisting of naphthalene sulfonic acid-based compounds, lignin sulfonic acid-based compounds, oxy polycarboxylic acid-based compounds, and melamine sulfonic acid-based compounds in powder form, and a component d: an alkali metal carbonate.

[0007] Patent Document 3 discloses a viscosity reducing agent for geopolymers containing a specific phosphate ester compound, a mixing agent for geopolymers containing the same, and a geopolymer forming composition.

[0008] Patent Document 4 discloses a backfill material comprising (a) slag or fly ash, (b) sodium aluminate, and (c) sodium silicate, wherein the molar ratio of SiO2 to Na2O in the sodium silicate is in the range of 0.9 to 2.7, the concentration of component (a) in the backfill material is in the range of 5 to 50% by mass, the concentration of component (b) in the backfill material is in the range of 10 to 45% by mass, and the concentration of sodium silicate in the backfill material is in the range of 10 to 28% by mass.

[0009] Furthermore, Non-Patent Document 1 discloses the definition, materials, mechanisms, challenges, and possibilities of geopolymers. Non-patent document 2 discloses a one-component geopolymer comprising alumina silica fine powder, a powdered alkaline compound, and aggregate, without the use of an alkaline solution. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] U.S. Patent Application Publication No. 2015 / 0321954 [Patent Document 2] Japanese Patent Publication No. 2002-88365 [Patent Document 3] Japanese Patent Publication No. 2020-138899 [Patent Document 4] Japanese Patent Publication No. 2019-77798 [Non-patent literature]

[0011] [Non-Patent Document 1] Concrete Engineering, Vol. 56, No. 5, pp. 409-414, The Japan Concrete Institute, published May 2018. [Non-Patent Document 2] Cement and Concrete Research, Vol. 103, pp. 21-34, Elsevier BV, November 2017. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] However, even when a cement dispersant is applied to a geopolymer composition, its fluidity does not improve compared to a cement-based slurry, such as concrete. On the other hand, increasing the amount of water to improve the fluidity of the geopolymer composition reduces the strength of the geopolymer after hardening.

[0013] This invention provides a geopolymer-type hydraulic composition that exhibits excellent fluidity and strength in its cured form. [Means for solving the problem]

[0014] The present invention relates to a hydraulic composition containing (A) fine aggregate [hereinafter referred to as component (A)], (B) metasilicate [hereinafter referred to as component (B)], (C) alumina silica fine powder [hereinafter referred to as component (C)], (D) bicarbonate [hereinafter referred to as component (D)], and (E) water [hereinafter referred to as component (E)], wherein the content of component (D) is 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B).

[0015] Furthermore, the present invention relates to a method for producing a hydraulic composition, comprising mixing components including (A) fine aggregate, (B) metasilicate (hereinafter referred to as component (B)), (C) alumina silica fine powder, (D) bicarbonate (hereinafter referred to as component (D)), and (E) water, wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B).

[0016] Furthermore, the present invention provides a step of obtaining a hydraulic composition by mixing components comprising (A) fine aggregate, (B) metasilicate [hereinafter referred to as component (B)], (C) alumina silica fine powder [hereinafter referred to as component (C)], (D) bicarbonate [hereinafter referred to as component (D)], and (E) water [hereinafter referred to as component (E)], wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B), Step (II) of curing the hydraulic composition to obtain a cured body, relates to a method for producing a cured body including

Advantages of the Invention

[0017] According to the present invention, a geopolymer-type hydraulic composition excellent in fluidity and strength of the cured body is provided. Since the present invention contributes to the effective utilization of industrial by-products and waste, reduction of CO₂ emissions, etc., it can be considered as a technology that contributes to, for example, SDGs Nos. 7, 9, 11, 12, 13, etc. for realizing a sustainable society in recent years.

Embodiments for Carrying Out the Invention

[0018] The present inventors have found that by adding a predetermined amount of the bicarbonate of component (D) to a hydraulic composition containing fine aggregate, metasilicate, alumina-silica fine powder and water, the fluidity of the hydraulic composition is improved, and the cured body of such a hydraulic composition exhibits sufficient strength. The reason why such an effect is manifested is not necessarily clear, but it is presumed as follows. As described above, geopolymers are formed by the dissolution of aluminum silicate by alkali and the subsequent formation of hydration products. Representative hydration products contributing to strength development include a complex of calcium, aluminum, and silicon oxides called C-S(A)-H. This hydration product grows rapidly under high pH and in an environment where calcium ions are dissolved. Component (D) reversibly immobilizes and releases calcium ions as calcium bicarbonate with relatively high solubility, thereby suppressing the decrease in fluidity as a hydraulic slurry accompanying the rapid growth of C-S(A)-H in the initial stage of hydration, and promoting the hydration reaction by intermittently releasing calcium ions as the age of the material progresses. In the present invention, it is considered that these actions are effectively manifested by the content of component (D) being within a predetermined range, achieving both fluidity and strength development of the cured body.

[0019] <Hydraulic Composition> The hydraulic composition of the present invention contains (A) fine aggregate, (B) metasilicate, (C) alumina silica fine powder, a predetermined amount of (D) bicarbonate, and (E) water.

[0020] (A) Component is fine aggregate. (A) Component may be natural sand or artificial sand. Examples of natural sand include river sand, land sand, mountain sand, sea sand, limestone sand, silica sand, chromite sand, zircon sand, olivine sand, alumina sand, natural lightweight fine aggregate, and crushed versions thereof. Examples of artificial sand include blast furnace slag fine aggregate, ferronickel slag fine aggregate, artificial lightweight fine aggregate, recycled fine aggregate, synthetic mullite sand, SiO2-based artificial sand with SiO2 as the main component, Al2O3-based artificial sand with Al2O3 as the main component, SiO2 / Al2O3-based artificial sand, SiO2 / MgO-based artificial sand, SiO2 / Al2O3 / ZrO2-based artificial sand, and SiO2 / Al2O3 / Fe2O3-based artificial sand. Here, the main component refers to the most abundant component in the sand. These can be used individually, or two or more can be used in combination.

[0021] (A) The components are preferably one or more selected from river sand, land sand, mountain sand, sea sand, lime sand, silica sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, artificial lightweight fine aggregate, natural lightweight fine aggregate, and recycled fine aggregate. These may be crushed sand.

[0022] From the viewpoint of the workability of the hydraulic composition (hydraulic slurry), the degree of amorphousness of the fine aggregate is preferably 30% or less, more preferably 20% or less, even more preferably 10% or less, and even more preferably 5% or less. There is no lower limit to the degree of amorphization of the fine aggregate, but for example, it may be 0% or more, or 1% or more.

[0023] (A) There are various methods for controlling the degree of amorphousness of component (A), but generally it is preferable to use a manufacturing method that rapidly cools the molten material. For example, there are methods of melting the raw material and rapidly cooling it by blowing it with air, or processing it in a flame and rapidly cooling it. In any case, the cooling method can be appropriately selected at various rates depending on the material and particle size. It is also possible to make amorphous material that has already crystallized by heat treatment and cooling treatment. Among these, the flame melting method, in which heating and cooling can be easily controlled, is preferred.

[0024] The degree of amorphousness of component (A) can be determined by the X-ray diffraction method shown below. Fine aggregate is crushed in a mortar and pressed onto the X-ray glass holder of a powder X-ray diffractometer for measurement. The powder X-ray diffractometer used is a MultiFlex manufactured by Rigaku Denki Co., Ltd. (light source: CuKα rays, tube voltage: 40kV, tube current: 40mA), and measurements are performed in the range of 2θ = 5 to 90° with a scanning interval of 0.01°, a scanning speed of 2° / min, and slits DS1, SS1, RS 0.3mm. In the range of 2θ = 10° to 50°, the X-ray intensities on the low and high angle sides are connected by straight lines, and the area below the line is defined as the background. The degree of crystallinity is determined using the software attached to the instrument, and subtracted from 100 to obtain the degree of amorphousness. Specifically, for the area above the background, amorphous peaks (halos) and each crystalline component are separated by curve fitting, the area of ​​each is determined, and the degree of amorphousness (%) is calculated using the following formula. Amorphization (%) = Area of ​​halo / (Area of ​​crystalline components + Area of ​​halo) × 100

[0025] Component (A) is preferably spherical in shape from the viewpoint of improving the fluidity of the hydraulic composition. Here, spherical in shape according to this embodiment means a round shape like a ball, and more specifically, a sphericity of 0.80 or higher, more preferably 0.85 or higher, even more preferably 0.90 or higher, even more preferably 0.95 or higher, and even more preferably 0.97 or higher. A sphericity of the fine aggregate according to this embodiment that is above the above lower limit is preferable from the viewpoint of fluidity. Furthermore, a sphericity of the fine aggregate according to this embodiment that is above the above lower limit is also preferable from the viewpoint of a smoother surface. Furthermore, the upper limit for sphericity is specifically 1 or less.

[0026] (A) The sphericity of component (A) is determined by image analysis of the particle image (photograph) obtained using an optical microscope or digital scope (e.g., Keyence VH-8000), thereby determining the area of ​​the particle projection cross-section and the perimeter of said cross-section, and then [Area of ​​particle projection cross-section (mm²)] 2 The value can be calculated by dividing the circumference of a perfect circle with the same area (mm) by the perimeter of the particle projection cross-section (mm), and then averaging the obtained values ​​for any 50 particles.

[0027] (A) The average particle size of component (A) is preferably 0.1 mm or more, more preferably 0.5 mm or more, and more preferably 5.0 mm or less, more preferably 2.0 mm or less, and even more preferably 1.0 mm or less, from the viewpoint of workability of the hydraulic composition. The average particle size of component (A) can be measured by the following method.

[0028] (Method for measuring average particle size) If the sphericity of the particle from the particle projection cross section is 1, the diameter (mm) is measured. On the other hand, if the sphericity is < 1, the major axis diameter (mm) and minor axis diameter (mm) of randomly oriented particles are measured, and (major axis diameter + minor axis diameter) / 2 is calculated. For any 100 particles, the obtained values ​​are averaged to obtain the average particle size (mm). The major axis diameter and minor axis diameter are defined as follows: When a particle is stabilized on a plane and its projection image onto the plane is sandwiched between two parallel lines, the width of the particle at which the distance between the parallel lines is minimized is called the minor axis diameter. On the other hand, the distance when the particle is sandwiched between two parallel lines perpendicular to these parallel lines is called the major axis diameter. The major and minor axis diameters of a particle can be determined by taking an image (photograph) of the particle using an optical microscope or digital scope (for example, Keyence VH-8000 model) and performing image analysis on the obtained image.

[0029] The hydraulic composition of the present invention may contain, per 100 parts by mass of the composition, component (A) in amounts of, for example, 10 parts by mass or more, more 20 parts by mass or more, more 30 parts by mass or more, from the viewpoint of strength development of the hardened body of the hydraulic composition, and 90 parts by mass or less, more 80 parts by mass or less, more 70 parts by mass or less, from the viewpoint of workability of the hydraulic composition.

[0030] Next, we will explain the metasilicate of component (B). Examples of metasilicates include concentrated aqueous solutions of sodium metasilicate, so-called water glass (e.g., composition formula Na2SiO3·nH2O, n=1.3~4.0). Examples of solid metasilicate hydrates include sodium metasilicate pentahydrate, sodium metasilicate nonahydrate, potassium metasilicate pentahydrate, potassium metasilicate nonahydrate, and magnesium metasilicate pentahydrate. Component (B) is preferably one or more selected from water glass, sodium metasilicate pentahydrate, and sodium metasilicate nonahydrate.

[0031] The hydraulic composition of the present invention may contain, per 100 parts by mass of the composition, component (B) in amounts of, for example, 0.1 parts by mass or more, further 0.5 parts by mass or more, further 1.0 part by mass or more, and 20 parts by mass or less, further 15 parts by mass or less, and further 10 parts by mass or less, from the viewpoint of strength development of the hardened body of the hydraulic composition.

[0032] From the viewpoint of the strength development of the hardened body of the hydraulic composition of the present invention, the content of component (B) may be, for example, 0.5 parts by mass or more, preferably 1.0 part by mass or more, more preferably 2 parts by mass or more, even more preferably 2.5 parts by mass or more, even more preferably 5 parts by mass or more, and for example, 50 parts by mass or less, preferably 35 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of component (A).

[0033] Next, we will explain the alumina silica fine powder, which is component (C). (C) Component includes a fine powder containing aluminosilicate (xM2O·yAl2O3·zSiO2·nH2O, where M is an alkali metal). Component (C) has the effect of eluting cations such as aluminum and silicon upon contact with alkaline compounds and / or aqueous solutions thereof, and acting as a source of these cations.

[0034] (C) The molar ratio of alumina (Al2O3) to silica (SiO2) of component (C) may be, from the viewpoint of strength development of the hardened product of the hydraulic composition, for example, 0.05 or more, more specifically 0.10 or more, and 1.00 or less, and more specifically 0.50 or less in terms of alumina / silica.

[0035] (C) Suitable examples of alumina silica fine powder include: 1) industrial waste and by-products such as blast furnace slag fine powder, fly ash, clinker ash, fluidized bed coal ash, municipal solid waste incineration ash molten slag fine powder, red mud, and sewage sludge incineration ash molten slag fine powder; 2) natural aluminosilicate minerals such as metakaolin and clay and their ceramics; and 3) volcanic ash. Of these, the industrial waste described in 1) above is particularly suitable because, compared to the other components, it has no restrictions on its origin and contributes to the effective utilization of industrial waste resources.

[0036] (C) Component may be one or more selected from blast furnace slag fine powder, fly ash, metakaolin, rice husk incineration ash, coconut husk incineration ash, municipal solid waste incineration ash, and sewage sludge incineration ash. (C) Component may preferably be one or more selected from blast furnace slag fine powder and fly ash.

[0037] In the present invention, two or more types of component (C) can be used. When two or more types of component (C) are used in the present invention, for example, when two or more types selected from blast furnace slag fine powder, fly ash, metakaolin, rice husk incineration ash, coconut husk incineration ash, municipal solid waste incineration ash, and sewage sludge incineration ash are used as component (C), it is preferable that the hydraulic composition of the present invention contains blast furnace slag fine powder as component (C) from the viewpoint of strength development of the hardened body of the hydraulic composition.

[0038] When the hydraulic composition of the present invention contains two or more components (C), and contains blast furnace slag fine powder as component (C), from the viewpoint of strength development of the hardened body of the hydraulic composition, the proportion of blast furnace slag fine powder in component (C) is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and for example 90 parts by mass or less, preferably 70 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of component (C). The hydraulic composition of the present invention preferably contains, as component (C), (C1) blast furnace slag fine powder and (C2) one or more selected from fly ash, metakaolin, rice husk incineration ash, coconut husk incineration ash, municipal solid waste incineration ash, and sewage sludge incineration ash.

[0039] Blast furnace slag powder is a by-product of iron refining in a blast furnace, and its main components are calcium oxide (CaO), silica (SiO2), and alumina (Al2O3). Its specifications are defined in JIS A 6206. In this invention, it is preferable to use blast furnace slag powder with a CaO content in the range of 30% by mass to 60% by mass. Fly ash is mainly composed of silica (SiO2) and alumina (Al2O3), and is classified into four types (I to IV) in JIS A 6201 based on particle size and flow value. JIS types I and II, which have fine particle size and high reactivity, are suitable. The CaO content in the fly ash may be 10.1% by mass or less.

[0040] (C) Component is the Blaine specific surface area (cm²). 2 The ratio ( / g) is, from the viewpoint of strength development of the hardened hydraulic slurry, for example, 1,500 or more, preferably 2,000 or more, more preferably 2,500 or more, even more preferably 3,000 or more, and even more preferably 3,500 or more. From the viewpoint of handlingability of the powdered hydraulic composition, it is, for example, 8,000 or less, preferably 7,500 or less, more preferably 7,000 or less, even more preferably 6,500 or less, and even more preferably 6,000 or less. The Blaine specific surface area of ​​component (C) is measured and calculated using a Blaine air permeability device specified in JIS R 5201.

[0041] The hydraulic composition of the present invention may contain, per 100 parts by mass of the composition, component (C) in amounts of, for example, 5 parts by mass or more, further 10 parts by mass or more, further 20 parts by mass or more, and 60 parts by mass or less, further 50 parts by mass or less, and further 40 parts by mass or less, from the viewpoint of strength development of the hardened body of the hydraulic composition.

[0042] (D) The component is a bicarbonate. (D) Examples of component include bicarbonates and, moreover, alkali metal bicarbonates. Examples of bicarbonates include potassium bicarbonate and sodium bicarbonate. The carbonate is preferably in solid form.

[0043] From the viewpoint of the fluidity of the hydraulic composition slurry, the hydraulic composition of the present invention contains 0.5 parts by mass or more, preferably 1.0 part by mass or more, more preferably 5.0 parts by mass or more, and 50 parts by mass or less, preferably 45 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 25 parts by mass or less, per 100 parts by mass of component (B).

[0044] The hydraulic composition of the present invention may contain, per 100 parts by mass of the composition, component (D) in amounts of, for example, 0.1 parts by mass or more, further 0.2 parts by mass or more, further 0.4 parts by mass or more, and 4.0 parts by mass or less, further 2.0 parts by mass or less, and further 1.0 part by mass or less, from the viewpoint of the fluidity of the hydraulic composition slurry.

[0045] Component (E) is water. The hydraulic composition of the present invention may contain, per 100 parts by mass of the composition, component (E) in amounts of, for example, 1.0 part by mass or more, further 3.0 parts by mass or more, further 5.0 parts by mass or more, from the viewpoint of the workability of the hydraulic composition, and 45.0 parts by mass or less, further 30.0 parts by mass or less, and further 15.0 parts by mass or less, from the viewpoint of the strength development of the hardened body of the hydraulic composition.

[0046] The hydraulic composition of the present invention may contain any component other than components (A), (B), (C), (D), and (E). Examples of optional components include water-reducing agents, air-entraining agents, fluidizing agents, hardening accelerators (alkaline stimulants), defoaming agents, rapid setting agents, shrinkage reducing agents, hardening retarders, and rust inhibitors. The hydraulic composition of the present invention may contain one or more of these optional components.

[0047] The hydraulic composition of the present invention may optionally contain cement, but care must be taken with its content as cement affects the initial hardening rate. Furthermore, from the viewpoint of providing a hydraulic composition with reduced cement content, a lower cement content is preferable. The hydraulic composition of the present invention may optionally contain cement, and the cement content may be less than 30 parts by mass, more preferably 20 parts by mass or less, more preferably 10 parts by mass or less, or more preferably 1 part by mass or less, per 100 parts by mass of component (C), and may also contain 0 parts by mass, i.e., no cement at all. Here, examples of cement include Portland cement, white Portland cement, blended cement, eco-cement, alumina cement, ultrafast-setting cement, grout cement, oil well cement, etc. The content of Portland cement in the hydraulic composition of the present invention may be within the above range relative to component (C).

[0048] The hydraulic composition of the present invention may be a hydraulic composition comprising component (A), component (B), component (C), and predetermined amounts of component (D) and component (E). In this case, the amount of each component can be selected from the content range indicated for each component, with the total amount of components in the composition being 100 parts by mass. The hydraulic composition of the present invention may be a composition for geopolymers.

[0049] The hydraulic composition of the present invention can be produced by mixing components (A) to (E). There are no particular limitations on the mixing order of each component. The present invention provides a method for producing a hydraulic composition, which involves mixing components (A), (B), (C), (D), and (E), wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B). The mixing amounts of components (A) to (E) in this production method can be selected from the content amounts described for each hydraulic composition of the present invention.

[0050] <Method for manufacturing a hardened body> The present invention relates to a method for producing a hardened body by curing the hydraulic composition of the present invention. The method for producing the cured article of the present invention may appropriately apply the matters described in the hydraulic composition of the present invention. Specific examples and preferred examples of components (A) to (E) in the method for producing the cured article of the present invention are the same as those for the hydraulic composition of the present invention.

[0051] The present invention provides a method for producing a cured product, comprising the steps of: (I) mixing components including (A), (B), (C), (D), and (E) to obtain a hydraulic composition, wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B); (II) A step of curing the hydraulic composition to obtain a hardened body, A method for producing a hardened body is provided, which includes the components (A) to (E). Components (A) to (E) are the same as those in the hydraulic composition of the present invention.

[0052] The mixing amounts of components (A) to (E) in step (1) can be selected from the content levels described in the hydraulic composition of the present invention. The hydraulic composition obtained in step (I) may be the hydraulic composition of the present invention. In step (I), the method, apparatus, and conditions for mixing the components containing components (A) to (E) are not particularly limited, and suitable methods, apparatus, and conditions can be appropriately selected for slurry preparation.

[0053] In step (II), the hydraulic composition obtained in step (I) is cured to obtain a cured body. The curing in step (II) can be carried out under general conditions for obtaining a cured geopolymer. In step (II), the curing temperature can be, for example, 20°C or higher, further 30°C or higher, further 40°C or higher, and 80°C or lower, and further 70°C or lower. In step (II), the curing time can be, for example, 1 hour or more and 8 days or less. [Examples]

[0054] The components used in the examples and comparative examples are shown below. (A) Composition: Mountain sand (from Joyo, Kyoto City, surface-dry specific gravity 2.54, coarseness 2.73, amorphity 1.1%, sphericity 0.86, average particle size 0.6 mm, in an oven-dry state) (B) Ingredients: Sodium metasilicate no. hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (C) Component (C-1): Blast furnace slag fine powder (Brain specific surface area: 4,200 cm²) 2 ( / g, alumina / silica molar ratio = 0.25) (C-2): Fly ash (JIS Class II, Blaine specific surface area: 3,500 cm²) 2 ( / g, alumina / silica molar ratio = 0.26) (D) Component (D-1): Potassium bicarbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (D-2): Sodium bicarbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (D') component (comparative component of (D) component) (D'-1): Sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (D'-2): Sodium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (E) Ingredients: Tap water (Wakayama City tap water)

[0055] <Examples and Comparative Examples> (1) Preparation of hydraulic compositions and their hardened bodies Components (A), (B), (C), (D), (D'), and (E) were added in the parts by mass shown in Table 1 to a Hobart mixer as described in JIS R 5201, and mixed at 140 rpm for 180 seconds to prepare the hydraulic compositions of the examples and comparative examples.

[0056] (2) Assessment of liquidity The mortar flow of the hydraulic composition prepared as described in (1) immediately after preparation was measured and recorded in accordance with JIS R 5201. The results are shown in Table 1.

[0057] (3) Evaluation of strength Using the hydraulic composition prepared as described in (1) immediately after preparation, φ5 × 10 cm mortar specimens were prepared in accordance with JSCE-F 506, sealed and cured at 20°C for 7 days, then demolded, and a compressive strength test was conducted in accordance with JSCE-G 505, with the uniaxial compressive strength (N / mm²) being the average value of n=2. 2 The following was recorded. The results are shown in Table 1. In the table, (D) / [(B)100] is the amount of parts by mass of component (B) per 100 parts by mass of component (B).

[0058] [Table 1]

[0059] As can be seen from Table 1, Examples 1-4 showed superior fluidity and strength development compared to Comparative Examples 1-4. It can be seen that even when using components that can function as alkaline stimulants, as in Comparative Examples 2 and 3, it is not possible to achieve both fluidity and strength as with the bicarbonate of component (D) of the present invention. This is thought to be because, as mentioned above, the predetermined amount of component (D) used in the present invention reversibly immobilizes and releases calcium ions as calcium bicarbonate, which has relatively high solubility, thereby suppressing the decrease in fluidity as a hydraulic slurry associated with the rapid growth of CS(A)-H in the early stages of hydration, while intermittently releasing calcium ions as the age progresses to promote the hydration reaction and achieve both fluidity and strength development of the hardened body. Furthermore, even when using component (D) of the present invention, it can be seen that if (D) / [(B)100] is outside the range of the present invention, as in Comparative Example 4, fluidity decreases and the hardening of the hydraulic composition becomes insufficient.

Claims

1. A hydraulic composition containing (A) fine aggregate [hereinafter referred to as component (A)], (B) metasilicate [hereinafter referred to as component (B)], (C) alumina silica fine powder [hereinafter referred to as component (C)], (D) bicarbonate [hereinafter referred to as component (D)], and (E) water, wherein the content of component (D) is 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B) (excluding compositions containing sodium gluconate).

2. (A) The hydraulic composition according to claim 1, wherein component (A) is one or more selected from river sand, land sand, mountain sand, sea sand, lime sand, silica sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, artificial lightweight fine aggregate, natural lightweight fine aggregate, and recycled fine aggregate.

3. The hydraulic composition according to claim 1 or 2, wherein component (C) is one or more selected from blast furnace slag fine powder, fly ash, metakaolin, rice husk incineration ash, coconut husk incineration ash, municipal solid waste incineration ash, and sewage sludge incineration ash.

4. The hydraulic composition according to claim 1 or 2, wherein component (B) is one or more selected from water glass, sodium metasilicate pentahydrate, and sodium metasilicate nonahydrate.

5. The hydraulic composition according to claim 1 or 2, wherein component (D) is potassium bicarbonate.

6. The hydraulic composition according to claim 1 or 2, wherein it optionally contains cement, and the cement content is less than 30 parts by mass per 100 parts by mass of component (C).

7. The hydraulic composition according to claim 1 or 2, wherein the content of component (D) is 5.0 parts by mass or more and 25 parts by mass or less per 100 parts by mass of component (B).

8. The hydraulic composition according to claim 1 or 2, wherein the content of component (D) is 0.1 parts by mass or more and 4.0 parts by mass or less per 100 parts by mass of the hydraulic composition.

9. A method for producing a hydraulic composition, comprising mixing (A) fine aggregate, (B) metasilicate [hereinafter referred to as component (B)], (C) alumina silica fine powder, (D) bicarbonate [hereinafter referred to as component (D)], and (E) water, wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B) (excluding compositions containing sodium gluconate).

10. A method for producing a hardened body (excluding compositions containing sodium gluconate), comprising the steps of: (I) mixing components containing (A) fine aggregate, (B) metasilicate (hereinafter referred to as component (B)), (C) alumina silica fine powder, (D) bicarbonate (hereinafter referred to as component (D)), and (E) water to obtain a hydraulic composition, wherein component (D) is mixed in an amount of 0.5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of component (B); and (II) curing the hydraulic composition to obtain a hardened body.

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