Additives for water hardening components

Abstract

This invention provides an additive for hydraulic compositions that suppresses the occurrence of slag. [Solution] An additive for hydraulic compositions, comprising (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more.

Description

[Technical Field]

[0001] The present invention relates to an additive for hydraulic compositions, a method for producing the additive for hydraulic compositions, a hydraulic composition, a method for producing a hydraulic composition, and a spraying method. [Background technology]

[0002] To prevent the collapse of exposed ground during tunnel excavation, a spraying method is employed that uses rapid-setting concrete or rapid-setting mortar, which are concrete mixed with a rapid-setting agent. In this method, sprayed concrete is usually prepared at a cement, aggregate, and water metering and mixing plant installed at the excavation site, and then transported by agitator truck to the spraying machine. The sprayed concrete and rapid-setting agent are then mixed in two lines: one line that uses the spraying machine's pump to air-pressure the sprayed concrete to the discharge port, and another line that uses a confluence pipe installed along the way to air-pressure the rapid-setting agent from the other side. The resulting rapid-setting sprayed concrete is then sprayed onto the ground surface to a specific thickness.

[0003] Patent Document 1 discloses an additive for a sprayable hydraulic composition comprising (A) a clay mineral having a swelling degree of 15 mL / 2 g or more and 50 mL / 2 g or less, and (B) one or more fasteners selected from cement mineral-based fasteners and aluminum-based fasteners. Furthermore, Patent Document 2 discloses a bentonite-mixed sprayed concrete in which a mixture comprising at least cement, bentonite, fine aggregate, and water is used, and the ratio of the bentonite mass to the cement mass is 20% by mass or less. Furthermore, Patent Document 3 discloses an alumina cement composition containing alumina cement, a pozzolanic substance, hectorite with a Li2O content of 0.7 to 2.5% by mass, inorganic fibers, and a fluidizing agent. Furthermore, Patent Document 4 discloses a powdered dust reducing agent comprising talc, bentonite, cellulose ether, deutan gum, polyacrylamide, and a specific defoaming agent in a specific mass ratio. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-70611 [Patent Document 2] Japanese Patent Publication No. 2004-26598 [Patent Document 3] Japanese Patent Publication No. 2007-223876 [Patent Document 4] Japanese Patent Publication No. 2014-125389 [Overview of the project] [Problems that the invention aims to solve]

[0005] Because sprayable hydraulic compositions are applied to the ground and other surfaces under high pressure, slag may form due to the high-pressure impact. Slag is the powder and water separated from hydraulic compositions such as mortar, i.e., the paste component, and it often contains a large amount of water. The formation of slag can locally increase the water content, and if low-strength concrete is produced, it may cause spalling of the concrete or make it unable to withstand the deformation of the ground. Furthermore, while smectite-type clay minerals exhibit a high slag suppression effect due to their water absorption, their high hygroscopicity means that they may not exhibit a high slag suppression effect depending on the humidity environment inside the tunnel, requiring on-site review of the concrete mix and spraying conditions each time. The present invention provides an additive for hydraulic compositions that suppresses the generation of slag, a method for producing the additive for hydraulic compositions, a hydraulic composition, a method for producing a hydraulic composition, and a spraying method. [Means for solving the problem]

[0006] The present invention relates to an additive for hydraulic compositions, comprising (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more.

[0007] The present invention also relates to a method for producing an additive for a hydraulic composition, which includes a step of mixing the component (A) and the component (B), and the mass ratio [(A) / (B)] of the mixing amount of the component (A) to the mixing amount of the component (B) is 0.5 or more.

[0008] The present invention also relates to a hydraulic composition containing the component (A) and the component (B), wherein the mass ratio [(A) / (B)] of the content of the component (A) to the content of the component (B) is 0.5 or more, a hydraulic powder, and water.

[0009] The present invention also relates to a hydraulic composition prepared by blending an additive for a hydraulic composition containing the component (A) and the component (B), wherein the mass ratio [(A) / (B)] of the content of the component (A) to the content of the component (B) is 0.5 or more, a hydraulic powder, and water.

[0010] The present invention also relates to a method for producing a hydraulic composition, which includes mixing an additive for a hydraulic composition containing the component (A) and the component (B), wherein the mass ratio [(A) / (B)] of the content of the component (A) to the content of the component (B) is 0.5 or more, a hydraulic powder, and water.

[0011] The present invention also relates to a spraying method, which includes mixing a hydraulic composition containing a hydraulic powder and water with an additive for a hydraulic composition containing the component (A) and the component (B), wherein the mass ratio [(A) / (B)] of the content of the component (A) to the content of the component (B) is 0.5 or more, and spraying the mixture onto an object. [Effect of the Invention]

[0012] According to the present invention, there are provided an additive for a hydraulic composition for suppressing the generation of norovirus, a method for producing an additive for a hydraulic composition, a hydraulic composition, a method for producing a hydraulic composition, and a spraying method. [Embodiments for Carrying Out the Invention]

[0013] The mechanism by which the additive for hydraulic compositions of the present invention and the hydraulic compositions containing the additive suppress the generation of slag is not clear, but it is presumed to be as follows. (A) Smectite-type clay minerals promote heteroaggregation with hydraulic powders, and even after the aggregated structure collapses due to the spraying discharge pressure, the recovery rate of the aggregated structure is accelerated, and the slag components are fixed before the slag separates from the mortar components, thereby suppressing the generation of slag when the hydraulic composition is sprayed onto the target surface. Furthermore, it is presumed that mixing (A) smectite-type clay minerals with (B) magnesium silicate having an aspect ratio of 1 or more and less than 10 reduces the frequency of contact between the smectite-type clay minerals and moisture, thereby suppressing the decrease in the water absorption capacity of the smectite-type clay minerals. In addition, it is presumed that (B) magnesium silicate with an aspect ratio of 1 or more and less than 10 suppresses contact between water-absorbing smectite-type clay minerals, preventing clumping, a phenomenon in which lumps of smectite-type clay minerals are formed, and thus preventing a decrease in the slag-suppressing effect when added to hydraulic compositions, even under high humidity conditions. Furthermore, the hydraulic additive for hydraulic compositions, the method for producing the hydraulic additive for hydraulic compositions, the hydraulic composition, the method for producing the hydraulic composition, and the spraying method of the present invention are not limited to the above-described mechanism of action.

[0014] <Additives for hydraulic compositions> The additive for hydraulic compositions of the present invention contains (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, and the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more. The additive for hydraulic compositions of the present invention may be an additive for hydraulic compositions for spraying, or an additive for suppressing slag generation in hydraulic compositions for spraying. In this specification, (A) smectite-type clay minerals are sometimes referred to as component (A), and (B) magnesium silicate with an aspect ratio of 1 or more and less than 10 is sometimes referred to as component (B).

[0015] <(A) component> (A) component is a smectite-type clay mineral. One or more than one kind of (A) component can be used. The type of the smectite-type clay mineral of the (A) component is not particularly limited, and it may be natural smectite or synthetic smectite. Examples of the smectite-type clay mineral of the (A) component include montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite. The smectite-type clay mineral forms a layered structure in which thin plate-like crystals with a thickness of about 1 nm are stacked, and cations such as alkali metals and alkaline earth metals generally exist between the crystals. There is no particular limitation on the cations present between the crystal layers of the smectite-type clay mineral. For example, one or more smectite-type clay minerals selected from Na (sodium)-type, Li (lithium)-type, K (potassium)-type, NH4 (ammonium)-type, Ca (calcium)-type, Mg (magnesium)-type, Ba (barium)-type, Al (aluminum)-type, Fe (iron)-type, Cu (copper)-type, and Zn (zinc)-type smectite-type clay minerals can be used.

[0016] (A) component is not particularly limited, but for example, a clay mineral represented by the following general formula (a1) is preferable. [SiEight(Mg a Al b )O 20 (OH)Four] X- ·Me X+ (a1) [In the formula, 0 < a ≤ 6, the 0 < b ≤ 4, x = 12 - 2a - 3b, and Me is at least one kind of Na, K, Li, Ca, Mg, and NH4, preferably at least one kind of Na and Ca. ]

[0017] From the viewpoint of further enhancing the slump inhibition effect of the hydraulic composition under high humidity, the average particle diameter of the (A) component is preferably 0.01 μm or more, more preferably 0.10 μm or more, still more preferably 1 μm or more, even more preferably 10 μm or more, and from the same viewpoint, it is preferably 500 μm or less, more preferably 200 μm or less, still more preferably 50 μm or less.

[0018] (A) The average particle size of component (A) is the arithmetic mean particle size of particles measured using a laser diffraction / scattering particle size distribution analyzer (e.g., LA-920 (manufactured by Horiba, Ltd.)) with ethanol (purity 99.5%) as the dispersion medium and ultrasound applied for 1 minute.

[0019] (A) The degree of swelling of component is preferably 30 mL / 2 g or more and 100 mL / 2 g or less, from the viewpoint of suppressing norovirus. (A) The degree of swelling of component is preferably 30 mL / 2 g or more, more preferably 35 mL / 2 g or more, even more preferably 40 mL / 2 g or more, and preferably 100 mL / 2 g or less, more preferably 80 mL / 2 g or less, and even more preferably 60 mL / 2 g or less, from the viewpoint of suppressing norovirus. If component (A) contains multiple types of clay minerals, this swelling degree is the swelling degree of a mixture of multiple types of component (A).

[0020] <Method for measuring swelling degree> In this invention, the degree of swelling is measured according to the swelling test method for bentonite (powdered) specified in JBAS104:77 of the Japan Bentonite Industry Association. Specifically, 2.0 g of the sample, adjusted to a moisture content of 8.0% by mass, is added in approximately 10 portions to a 100 mL stoppered graduated cylinder containing 100 mL of distilled water. At this time, the next addition is made only after the previous addition has settled at the bottom of the graduated cylinder. After standing for 24 hours, the apparent volume of the sample mass at the bottom of the graduated cylinder, which has swollen, is read from the scale of the graduated cylinder and displayed as the degree of swelling (mL / 2g).

[0021] Commercially available products containing montmorillonite include Bengel, Bengel HV, Bengel A, Bengel FW, Bengel 31, and Bengel W-100 from Toyojun Mining Co., Ltd., Kunipia G and Kunipia F from Kunimine Industries Co., Ltd., Western Bond from American Colloid Company, and Yellowstone from Dresser Minerals.

[0022] Commercially available products containing saponite include Vanderbilt's Beegum T, Beegum HV, Beegum F, and Beegum K, as well as Smecton SA from Kunimine Industries Co., Ltd.

[0023] Commercially available products containing hectorite include Smecton SWN and Smecton SWF manufactured by Kunimine Industries Co., Ltd., Hectabrite AW, Hectabrite 200 and Benton EW manufactured by American Colloid Corporation, and Macaloid manufactured by National Reed Corporation.

[0024] Examples of commercially available products containing stevensite include Smecton ST manufactured by Kunimine Industries Co., Ltd.

[0025] Various synthetic smectites are also commercially available, including Ionite H from Mizusawa Chemical Industries, Ltd., SWN and SAN from Coop Chemical Co., Ltd., Laponite from Laporte Industry, and Laponite XLS and Laponite XLG from Lockwood.

[0026] (A) Component may be a clay mineral containing smectite. (A) Component may be a clay mineral having a smectite content of preferably 30% by mass or more and 100% by mass or less. Examples of clay minerals containing smectite for component (A) include "Bentonite", "Detasoft GIS", "Detasoft GIB", and "Detasoft GISW" from Raviosa, "Odosolve K-400" from Kurosaki Hakudo Kogyo Co., Ltd., "Round Rhozil DGA212", "Round Rhozil PR414", "Round Rhozil DG214", "Round Rhozil DGA Powder", and "Furasoft-1 Powder" from Süd Chemi, and Pure Bentonite, Standard Bentonite, and Premium Bentonite from CSM.

[0027] <(B) component> (B) Component is magnesium silicate with an aspect ratio of 1 or more and less than 10. Component (B) may be used in one or more forms. Component (B) may be a mineral consisting of magnesium hydroxide and silicate [except for those that fall under component (A)]. Component (B) may be hydrated magnesium silicate or a magnesium-containing hydrated silicate mineral [excluding those that fall under component (A)].

[0028] Component (B) may be magnesium silicate having a particle shape with an aspect ratio of 1 or more and less than 10. Alternatively, component (B) may be a magnesium-containing silicate mineral in which particles with an aspect ratio of 1 or more and less than 10 account for 90% or more of the total particles.

[0029] Component (B) may be one or more selected from talc, sepiolite, antigorite, forsterite chrysotile, lizardite, enstatite, and serpentinite, and talc is preferred from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity. Magnesium silicate, not just talc, is generally considered highly safe and stable even in the form of fine particles.

[0030] Component (B) is a mineral in which, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, the proportion of particles with an aspect ratio of 1 or more and less than 10 among the total particles of component (B) is preferably 90% or more, more preferably 95% or more, even more preferably 98% or more, and from the same viewpoint, preferably 100% or less. This proportion is measured by the following method. Furthermore, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, it is preferable that the proportion of particles with an aspect ratio of 1 to 4 among the total particles of component (B) be within the above range.

[0031] <Method for measuring the proportion of particles with an aspect ratio of 1 or more and less than 10 among all particles of component (B), and the average value of the aspect ratio of component (B)> The aqueous dispersion of component (B) is placed between a slide glass and a cover glass, and photographed using a digital microscope (DSX1000, manufactured by OLYMPUS Corporation, 200x magnification) in the simplified deflection mode. 100 particles are randomly selected from the obtained image, their long and short axes are measured, and the aspect ratio of each particle is calculated. Based on the number of particles with an aspect ratio of 1 or more and less than 10, the proportion of particles with an aspect ratio of 1 or more and less than 10 among all selected particles is calculated and taken as the proportion of particles with an aspect ratio of 1 or more and less than 10 among all particles of component (B). The proportion of particles with an aspect ratio of 1 or more and less than 4 among all particles of component (B) is calculated using the same method. Furthermore, the average aspect ratio of all selected particles is calculated and used as the average aspect ratio of component (B).

[0032] (B) Component has an average aspect ratio of preferably 1 or more, more preferably 1.1 or more, and preferably 4 or less, and more preferably 2.5 or less, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity.

[0033] The average particle size of component (B) is preferably 0.01 μm or more, more preferably 0.1 μm or more, even more preferably 1 μm or more, even more preferably 10 μm or more, and from the same viewpoint, preferably 600 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, and even more preferably 50 μm or less. The average particle diameter of component (B) is the average particle diameter of its diameter if (B) is spherical, and the average particle diameter of the circumscribed sphere with its major axis as the diameter if (B) is not spherical.

[0034] (B) The average particle size of component (B) is the arithmetic mean particle size of particles measured using a laser diffraction / scattering particle size distribution analyzer (e.g., LA-920 (manufactured by Horiba, Ltd.)) with ethanol (purity 99.5%) as the dispersion medium and ultrasound applied for 1 minute.

[0035] In the additive for hydraulic compositions of the present invention, the particle size ratio (r) of the average particle size of component (A) to the average particle size of component (B) is A / r B From the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, the value is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.1 or more, and from the same viewpoint, preferably 1000 or less, more preferably 100 or less, even more preferably 10 or less, and even more preferably 1 or less.

[0036] <Composition, etc.> The additive for hydraulic compositions of the present invention contains component (A) in an amount of preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, from the viewpoint of further enhancing the slag-suppressing effect of the hydraulic composition, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of further enhancing the slag-suppressing effect of the hydraulic composition under high humidity. The preferred content of component (A) above may be the preferred content of component (A) in a hydraulic composition additive that does not contain a rapid setting agent, which will be explained in detail later. Also, if the hydraulic composition additive contains a rapid setting agent, the preferred content of component (A) above may be the preferred content of component (A) in a hydraulic composition additive that does not contain a rapid setting agent.

[0037] (A) The provision regarding the mass of component (A) is that if component (A) is a synthetic smectite or other substance with a smectite content of 100% by mass, the mass of component (A) may be used. On the other hand, when using a composition containing smectite, such as natural smectite, the smectite content shall be measured by the amount of methylene blue adsorbed according to the smectite content measurement method described below, and the measured smectite content shall be taken as the mass of component (A). The same applies to the definition of the mass of component (A) below unless otherwise specified. The measurement of the smectite content shall be performed on the dried component (A) after drying it in a hot air dryer at 105°C for 1 hour as a pretreatment.

[0038] <(A) Method for measuring the smectite content> (1) Measurement of methylene blue adsorption (A) The amount of methylene blue adsorbed by component (A) shall be measured by the following method in accordance with the Japanese Industrial Standard (JIS Z 2451:2019). <Reagents> 10 mmol / L aqueous solution of methylene blue (molecular weight 374) 0.2% by mass aqueous solution of sodium pyrophosphate (Na4P2O7) <How to operate> Place approximately 0.4 g of component (A) into a 100 mL screw-cap tube, and add 40 g of a 0.2% by mass aqueous solution of sodium pyrophosphate. Disperse this mixture in an ultrasonic cleaner (ASUCLEANER, ASU-3, AS ONE Corporation) for 30 minutes, then heat in 80°C warm water for 30 minutes. Add 10 mmol / L methylene blue aqueous solution dropwise to the dispersed mixture while stirring with a magnetic stirrer. After each drop, use a glass Pasteur pipette to draw up a portion of the supernatant and drop it onto filter paper. Add the supernatant until a spot of approximately 10 mm in diameter is formed on the filter paper. Repeat this operation until a halo is observed around the spot. Once a halo is observed, the titration is terminated when the width of the halo exceeds 2 mm. The amount of methylene blue adsorbed (mmol) is calculated by multiplying the titration volume (L) by the concentration of the methylene blue aqueous solution (10 mmol / L) and converting this product to an amount per 100 g of component (A). (2) Calculation of smectite content The calculation of the smectite content of component (A) is performed with reference to "A proposed method for the determination of small amounts of smectites in clay mineral mixtures, Proceedings of British Ceramics Society 28 137-145, 1979" and "Journal of the Japan Society of Civil Engineers, Series C (Geosphere Engineering), Vol. 76, No.1, 26-39, 2020: Evaluation of Montmorillonite Content of Bentonite Considering Measurement Accuracy of Methylene Blue Adsorption Test". Specifically, 140 mmol / 100g was adopted as the saturation adsorption amount of methylene blue for smectite. The smectite content of component (A) was calculated by dividing this saturation adsorption amount by the measured methylene blue adsorption amount of component (A) and multiplying by 100.

[0039] The additive for hydraulic compositions of the present invention contains component (B) in an amount of preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of further enhancing the slag-suppressing effect of the hydraulic composition under high humidity, and preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of further enhancing the slag-suppressing effect of the hydraulic composition. The preferred content of component (B) above may be the preferred content of component (B) in a hydraulic composition additive that does not contain a rapid setting agent, which will be explained in detail later. Furthermore, if the hydraulic composition additive contains a rapid setting agent, the preferred content of component (B) above may be the preferred content of component (B) in a hydraulic composition additive that does not contain a rapid setting agent.

[0040] If component (A) contains component (B), the portion of component (B) contained in component (A) shall be included in the content of component (B). However, component (B) contained in hydraulic powders and aggregates, which will be explained in detail later, shall not be included in the content of component (B). The same provisions apply hereafter to the content of component (B) unless otherwise specified. The content of component (B) in component (A) is quantified by Rietveld analysis by fitting the theoretical profile of each component (B) to the powder X-ray diffraction chart (measured profile) of the composition obtained using an X-ray structural diffractometer (e.g., MiniFlex600 desktop X-ray diffractometer, manufactured by Rigaku Corporation). Analysis software (e.g., PDXL powder X-ray analysis software, manufactured by Rigaku Corporation) can be used for this quantification.

[0041] In the additive for hydraulic compositions of the present invention, the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is preferably 0.5 or more, more preferably 1.0 or more, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, and preferably 9 or less, more preferably 3 or less, and even more preferably 1.4 or less, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition.

[0042] The additive for hydraulic compositions of the present invention has a water content that, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, is preferably 0% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, and from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition, is preferably 25% by mass or less, more preferably 18% by mass or less, and even more preferably 14% by mass or less.

[0043] The water content of the additive for hydraulic compositions of the present invention is calculated by measuring approximately 2 g of the additive into an aluminum cup, drying it in a hot air dryer at 105°C for 1 hour, and then determining the percentage of the decrease in mass of the additive before and after drying relative to the mass of the additive before drying (mass%).

[0044] The additive for the hydraulic composition of the present invention may optionally contain a rapid setting agent or a polymeric thickener, such as polyalkylene oxide, (meth)acrylic acid polymer, cellulose polymer, or (meth)acrylamide polymer, as long as it does not impair the effects of the present invention. These optional components may be mixed into the hydraulic composition separately from the additives for the hydraulic composition of the present invention.

[0045] <Accelerating agent> The rapid setting agent can be used in any form, such as powder, liquid, or a combination of both. Examples of rapid setting agents include one or more selected from cement mineral-based rapid setting agents and aluminum-based rapid setting agents.

[0046] Examples of cement mineral-based rapid setting agents include one or more selected from calcium aluminate, calcium sulfoaluminate, and calcium aluminate. Examples of aluminum-based rapid setting agents include one or more aluminum salts selected from aluminum hydroxide, sodium aluminate, potassium aluminate, aluminum sulfate, aluminum chloride, potassium aluminum sulfate, potassium alum, iron alum, and ammonium iron alum. From the viewpoint of strength development, the rapid setting agent is preferably one or more selected from calcium aluminate, calcium sulfoaluminate, calcium aluminate, aluminum sulfate, sodium aluminate, and aluminum sulfate; more preferably one or more selected from calcium aluminate, calcium sulfoaluminate, and aluminum sulfate; and even more preferably one or more selected from calcium aluminate and aluminum sulfate. The fastening agent may include gypsum, alkali carbonates such as sodium carbonate, potassium carbonate, and sodium bicarbonate, sodium sulfate, and calcium hydroxide.

[0047] More specifically, the following rapid setting agents can be used: Denka Corporation's Denkanatomic series, Denkanatomic US-32, Denkanatomic US-50, Denkanatomic TYPE-5, Denkanatomic TYPE-10, Denkanatomic Z, Natomic L, Natomic LSA, Natomic USS, Natomic HSS, Denka Σ Shot V; Taiheiyo Material Corporation's Taiheiyo Shot Master series, Taiheiyo Shot Master A, Taiheiyo Shot Master A (for high strength), Taiheiyo Shot Master H; Pozzolith Solutions Co., Ltd.'s Master Lock series, Master Lock SA161, Master Lock SA167, Master Lock SA178, Master Lock SA143, Master Lock SA446; and Sika Japan Corporation's Signit series, Signit P10AF, Signit L53AF, Signit U, etc.

[0048] <Calcium Aluminate> Calcium aluminate (hereinafter referred to as CA) is a general term for compounds mainly composed of CaO and Al₂O₃ and having hydration activity. A part of CaO and / or Al₂O₃ is replaced by alkali metal oxides, alkaline earth metal oxides, silicon oxide, titanium oxide, iron oxide, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal sulfates, etc. Or a substance in which these are slightly dissolved in a substance mainly composed of CaO and Al₂O₃. CA may be either crystalline or amorphous.

[0049] Specific examples of crystalline CA are C₃A, C₁₄A₅ in which an alkali metal is dissolved in it, CA, C₁₂A₇, C₁₁A₇·CaF₂, C₄A·Fe₂O₃, and C₃A₃·CaSO₄, etc. when CaO is denoted as C and Al₂O₃ is denoted as A. Also, for example, it may contain Na₂O, K₂O, and Li₂O. Amorphous calcium aluminate is preferred because of its good flash setting property.

[0050] Note that the calcium aluminate used in this embodiment may be contaminated with trace amounts of alkali metals and / or alkaline earth metals from industrial raw materials, and there is a possibility that CA containing these alkali metals and / or alkaline earth metals is partially generated. However, it is not restricted by the presence of these small amounts of alkali metals and / or alkaline earth metals in any way.

[0051] The CaO / Al₂O₃ molar ratio of calcium aluminate is not particularly limited. Considering the extremely early strength development property, the molar ratio is preferably 2.0 or more and 3.0 or less, and more preferably 2.2 or more and 2.8 or less. When the molar ratio is 2.0 or more, the extremely early setting property can be improved. When it is 3.0 or less, good long-term strength development property can be easily obtained.

[0052] The Blaine specific surface area of calcium aluminate (hereinafter sometimes simply referred to as "Blaine") is preferably 4,000 cm 2 / g or more and 8,000 cm 2 / g or less, and more preferably 5,000 cm 2 / g or more and 7,000 cm2 It is more preferable that the specific surface area is 4,000 cm² or less. 2 / g or more 8,000cm 2 Having a value of less than / g facilitates the development of initial strength and improves the handling properties of mortar and / or concrete during spraying.

[0053] <Alum> Alum is effective in accelerating the loss of fluidity in cement mortar and cement concrete immediately after mixing, and in accelerating the development of strength over approximately one day. While the type of alum is not particularly limited, any type of alum can be used or combined, such as potassium alum, chromium alum, iron alum, ammonium alum, sodium alum, or natural alum. It is particularly preferable to include at least one alum selected from the group consisting of potassium alum, sodium alum, and ammonium alum, as this is what causes the loss of fluidity in cement mortar and cement concrete.

[0054] <Gypsum> Any type of gypsum can be used: anhydrous, hemihydrate, or dihydrate. Of these, anhydrous gypsum is preferred from the viewpoint of good strength development. From the perspective of initial strength development, the particle size of gypsum should be 2,000 cm² in Blaine specific surface area. 2 Preferably 3,000 cm² or more 2 / g or more 6,000cm 2 A value of less than / g is more preferable. The Blaine specific surface area value used herein can be determined in accordance with JIS R 5201 (Physical Testing Methods for Cement).

[0055] <Calcium hydroxide> Calcium hydroxide is an effective material for ensuring initial fluidity reduction and long-term strength development. While not specifically limited, calcium hydroxide can include slaked lime produced when quicklime is hydrated, and carbide slag produced when carbide is hydrated. Commercially available calcium hydroxide can also be used, and any combination of the above is possible.

[0056] The Blaine specific surface area of ​​calcium hydroxide is 5,000 cm². 2 / g or more 15,000cm 2 It is preferable that the amount be less than or equal to 7,000 cm². 2 / g or more 13,000cm 2 It is more preferable that the specific surface area is 5,000 cm² or less. 2 / g or more 15,000cm 2 By keeping the amount below / g, rapid hardening properties and long-term strength development can be ensured, making it easier to obtain good initial strength development.

[0057] <Alkaline Carbonate> Alkali carbonate refers to alkali metal carbonate salts, which can significantly improve the setting properties and initial strength development of powdered rapid setting agents. While not particularly limited, examples include one or more selected from lithium carbonate, sodium carbonate, sodium sesquicarbonate, potassium carbonate, sodium bicarbonate, and sodium bicarbonate. Sodium carbonate, potassium carbonate, sodium sesquicarbonate, sodium bicarbonate, and sodium bicarbonate are particularly effective in improving setting and initial strength development, and combinations of one or more of these are also possible. Preferably, at least one selected from the group consisting of sodium carbonate, sodium sesquicarbonate, sodium bicarbonate, and potassium carbonate is used.

[0058] When the additive for hydraulic compositions of the present invention contains a rapid setting agent, the additive for hydraulic compositions of the present invention contains the rapid setting agent in an amount of 75% by mass or more, more preferably 85% by mass or more, and even more preferably 92% by mass or more, from the viewpoint of suppressing slag formation and strength development, and from the viewpoint of suppressing the generation of slag and changes in shape of the hydraulic composition, it contains 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less.

[0059] When the additive for hydraulic compositions of the present invention contains a rapid setting agent, the mass ratio of the content of component (A) to the content of the rapid setting agent [(rapid setting agent) / (A)] in the additive for hydraulic compositions of the present invention is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 1.0 or more, and preferably 90 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, even more preferably 30 or less, and even more preferably 20 or less.

[0060] The hydraulic additive of the present invention may be a hydraulic additive comprising component (A) and component (B). Furthermore, the additive for hydraulic compositions of the present invention may be an additive for hydraulic compositions comprising component (A), component (B), and a rapid setting agent. In the additive for hydraulic compositions of the present invention, the preferred amounts of component (A), component (B), and the rapid setting agent can be applied by replacing the preferred content in the hydraulic composition of the present invention with the amounts of the components. Furthermore, in the additive for hydraulic compositions of the present invention, the mass ratio of the amount of each component can be applied by replacing the mass ratio of the preferred content in the hydraulic composition of the present invention with the mass ratio of the amount of each component.

[0061] <Method for producing the additive for the hydraulic composition of the present invention> The present invention provides a method for producing an additive for hydraulic compositions, comprising the step of mixing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio [(A) / (B)] of the amount of component (A) mixed to the amount of component (B) mixed is 0.5 or more. The present invention may be a method for producing an additive for hydraulic compositions, in which component (A) and component (B) are mixed in a mass ratio [(A) / (B)] of 0.5 or more.

[0062] In the method for producing the additive for hydraulic compositions of the present invention, preferred embodiments of component (A) and component (B) are the same as preferred embodiments of component (A) and component (B) of the additive for hydraulic compositions of the present invention described above. Furthermore, in the method for producing the additive for hydraulic compositions of the present invention, any of the components listed in the additive for hydraulic compositions of the present invention may be mixed as desired.

[0063] In the method for producing the additive for hydraulic compositions of the present invention, the preferred mixing amounts of component (A), component (B), and optional component can be applied by substituting the preferred content of each component of the hydraulic composition additive of the present invention with the mixing amount.

[0064] In the method for producing the additive for hydraulic compositions of the present invention, the mass ratio [(A) / (B)] of the amount of component (A) mixed to the amount of component (B) mixed is 0.5 or more, preferably 1.0 or more, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition under high humidity, and preferably 9 or less, more preferably 3 or less, and even more preferably 1.4 or less, from the viewpoint of further enhancing the slag suppression effect of the hydraulic composition.

[0065] <Hydraulic composition> The present invention provides a hydraulic composition comprising (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, a hydraulic powder, and water. The hydraulic composition of the present invention may be a hydraulic composition containing the hydraulic composition additive of the present invention, hydraulic powder, and water. The hydraulic composition of the present invention may be a hydraulic composition for spraying.

[0066] In the hydraulic composition of the present invention, preferred embodiments of component (A), component (B), and additive for hydraulic composition are the same as preferred embodiments of component (A), component (B), and additive for hydraulic composition in the additive for hydraulic composition of the present invention described above. Furthermore, the hydraulic composition of the present invention or the additive for the hydraulic composition may optionally contain any of the components listed in the additive for the hydraulic composition of the present invention. In the hydraulic composition of the present invention, preferred embodiments such as the content of component (A), component (B), and other optional components contained in the additive for hydraulic composition and the mass ratio of said content [(A) / (B)] are the same as preferred embodiments such as the content of component (A) and component (B) in the additive for hydraulic composition of the present invention.

[0067] <Hydraulic powder> The hydraulic powder used in the hydraulic composition of the present invention is a powder that hardens when mixed with water, and examples include ordinary Portland cement, rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, moderate-heat Portland cement, white Portland cement, alumina cement, and eco-cement (e.g., JIS R 5214). Among these, from the viewpoint of expanding the range of hydraulic compositions, cement selected from rapid-hardening Portland cement, ordinary Portland cement, sulfate-resistant Portland cement, and white Portland cement is preferred, and rapid-hardening Portland cement and ordinary Portland cement are more preferred.

[0068] Furthermore, the hydraulic powder may contain blast furnace slag, fly ash, silica fume, anhydrous gypsum, etc., and may also contain non-hydraulic limestone fine powder, etc. The hydraulic powder may be blast furnace cement, fly ash cement, or silica fume cement, which are mixtures of cement with blast furnace slag, fly ash, silica fume, etc.

[0069] <Aggregates> The hydraulic composition of the present invention may optionally contain aggregate. The aggregate may be selected from fine aggregate and coarse aggregate. Examples of fine aggregate include those specified in JIS A 0203-2014, number 2311. Examples of fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand and their crushed sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate. Furthermore, coarse aggregates can be those specified in JIS A 0203-2014, number 2312. For example, coarse aggregates include river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stone of these, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate. Fine aggregate and coarse aggregate may be mixed from different types, or a single type may be used. The hydraulic composition of the present invention may contain fine aggregate. The amount of fine aggregate used in the hydraulic composition of the present invention is preferably 500 kg / m³. 3 Above, a comfortable 600 kg / m 3 In addition, preferably 2000 kg / m 3 More preferably, 1700 kg / m 3 The following applies: In the hydraulic composition of the present invention, the fine aggregate ratio is preferably 35% or more, more preferably 45% or more, preferably 100% or less, more preferably 70% or less, and even more preferably 65% ​​or less. Here, the fine aggregate ratio is the volume content of fine aggregate in the total aggregate.

[0070] <Water> The hydraulic composition of the present invention contains water. Examples of water include tap water, groundwater, lake water, and river water.

[0071] The hydraulic composition of the present invention has a water / hydraulic powder ratio (W / C) of preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less, from the viewpoint of suppressing slag. In other words, the hydraulic composition of the present invention contains water in an amount of preferably 30 parts by mass or more, more preferably 35 parts by mass or more, even more preferably 40 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less, per 100 parts by mass of hydraulic powder. The water / hydraulic powder ratio (W / C) represents the proportion of water to hydraulic powder in the hydraulic composition, expressed as a mass percentage (mass%), and is calculated as (water / hydraulic powder) × 100. Furthermore, if the hydraulic powder contains powders selected from those having properties that harden through hydration reactions such as cement, as well as powders having pozzolanic properties, powders having latent hydraulic properties, and stone powder (calcium carbonate powder), the amounts of these powders are also included in the amount of hydraulic powder in this invention. Also, if the powder having properties that harden through hydration reactions contains a high-strength admixture, the amount of the high-strength admixture is also included in the amount of hydraulic powder. However, if these components are included in the hydraulic composition additive or rapid-setting agent of this invention, the components included in the hydraulic composition additive and rapid-setting agent of this invention are not included in the amount of hydraulic powder. This is also true for other parts of mass where the mass of the hydraulic powder is relevant.

[0072] The hydraulic composition of the present invention contains the above-mentioned additive for hydraulic composition in an amount of 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, and preferably 10% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less, relative to the hydraulic powder in the hydraulic composition, from the viewpoint of suppressing slag formation.

[0073] The hydraulic composition of the present invention contains component (A) in an amount of 0.03% by mass or more, more preferably 0.04% by mass or more, even more preferably 0.05% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, relative to the hydraulic powder in the hydraulic composition, from the viewpoint of suppressing slag formation.

[0074] If the hydraulic composition of the present invention contains a rapid setting agent, the hydraulic composition of the present invention contains the rapid setting agent in an amount of preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, even more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the hydraulic powder contained in the hydraulic composition, from the viewpoint of suppressing slag.

[0075] <Dispersant> The hydraulic composition of the present invention may optionally contain a dispersant. From the viewpoint of dispensing workability, a polycarboxylic acid-based dispersant is preferred.

[0076] Polycarboxylic acid-based dispersants can include copolymers of a monoester of polyalkylene glycol and (meth)acrylic acid with a carboxylic acid such as (meth)acrylic acid (for example, compounds described in Japanese Patent Publication No. 8-12397), copolymers of an unsaturated alcohol having polyalkylene glycol with a carboxylic acid such as (meth)acrylic acid, and copolymers of an unsaturated alcohol having polyalkylene glycol with a dicarboxylic acid such as maleic acid. Here, (meth)acrylic acid refers to a carboxylic acid selected from acrylic acid and methacrylic acid.

[0077] If the hydraulic composition of the present invention contains a dispersant, the hydraulic composition of the present invention contains the dispersant in an amount of preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.07 parts by mass or more, and preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less, per 100 parts by mass of the hydraulic powder contained in the hydraulic composition, from the viewpoint of discharge workability and slag suppression.

[0078] The hydraulic composition of the present invention may optionally contain one or more of the following: a high-performance water-reducing agent, a high-performance AE water-reducing agent, a water-reducing agent including an AE water-reducing agent and a fluidizing agent, an expanding agent, a hardening accelerator, a hardening retarder, a polymer for cement, a foaming agent, a waterproofing agent, a rust inhibitor, a shrinkage reducing agent, a pigment, a fiber, a water-repellent agent, an efflorescence inhibitor, a thickening agent, etc.

[0079] The surfaces to which the hydraulic composition of the present invention is sprayed include tunnels such as roads, railways, and waterways, slopes formed by excavation and embankment, underground spaces, and concrete structures that are subject to repair by spraying methods.

[0080] The hydraulic composition of the present invention may be a hydraulic composition comprising an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, a hydraulic powder, and water. The hydraulic composition of the present invention may be a hydraulic composition comprising the additive for hydraulic compositions of the present invention, a hydraulic powder, and water. The hydraulic composition of the present invention may further contain any of the optional components described above in the hydraulic composition of the present invention. Furthermore, in the hydraulic composition of the present invention, the preferred blending amounts of the additive for hydraulic composition, hydraulic water powder, and optional components can be applied by substituting the preferred content in the hydraulic composition of the present invention described above.

[0081] <Method for producing a hydraulic composition> The present invention provides a method for producing a hydraulic composition, comprising mixing an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, with hydraulic powder and water.

[0082] The method for producing the hydraulic composition of the present invention may be a method for producing a hydraulic composition in which the additive for the hydraulic composition of the present invention, a hydraulic powder, and water are mixed. Furthermore, the method for producing the hydraulic composition of the present invention may be a method for producing a hydraulic composition by mixing a hydraulic powder with water to obtain a hydraulic composition, and then mixing that with an additive for the hydraulic composition of the present invention. The method for producing the hydraulic composition of the present invention may be a method for producing a hydraulic composition for spraying.

[0083] In the method for producing the hydraulic composition of the present invention, preferred embodiments of component (A), component (B), and additive for hydraulic composition are the same as preferred embodiments of component (A), component (B), and additive for hydraulic composition in the additive for hydraulic composition of the present invention described above. Furthermore, preferred embodiments of hydraulic powder and water are the same as preferred embodiments of hydraulic powder and water in the hydraulic composition of the present invention. Furthermore, in the method for producing the hydraulic composition of the present invention, the hydraulic composition or the additive for the hydraulic composition may optionally contain any of the optional components listed in the additive for the hydraulic composition or the hydraulic composition of the present invention.

[0084] In the method for producing the hydraulic composition of the present invention, preferred embodiments such as the content of component (A), component (B), and other optional components contained in the additive for the hydraulic composition and the mass ratio of said content [(A) / (B)] are the same as preferred embodiments such as the content of component (A) and component (B) and the mass ratio of said content [(A) / (B)] in the additive for the hydraulic composition of the present invention. Furthermore, in the method for producing the hydraulic composition of the present invention, the amount or ratio of the additive for the hydraulic composition, the hydraulic powder, and the water can be applied by replacing the content or mass ratio of each component in the hydraulic composition of the present invention with the amount or ratio of the content. The same applies to the spray application method, which will be explained in detail later.

[0085] <Spray application method> The present invention provides a spraying method in which a hydraulic composition containing hydraulic powder and water is mixed with an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, and the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, and the mixture is sprayed onto an object. Furthermore, the spraying method of the present invention may be a spraying method in which the hydraulic composition of the present invention is sprayed onto a target surface. Furthermore, the additive for the hydraulic composition may be the additive for the hydraulic composition of the present invention. In the spraying method of the present invention, a rapid-setting agent may be mixed with the hydraulic composition, and the hydraulic composition mixed with the rapid-setting agent may be sprayed onto the target surface.

[0086] The spraying method of the present invention preferably involves separately pumping the hydraulic composition of the present invention and the additive and / or quick-setting agent for the hydraulic composition and / or the quick-setting agent, and then combining and mixing them, or, before combining and mixing, adding water to a mixed powder of the additive and powder quick-setting agent for the hydraulic composition to form a slurry, and then combining and mixing the slurry containing the additive and quick-setting agent for the hydraulic composition with the hydraulic composition and spraying it. A wet spraying method is preferred. Examples of wet spraying methods include mixing and kneading hydraulic powder, aggregate, and water, pumping it under air pressure, and then combining and mixing the additive and quick-setting agent for the hydraulic composition and spraying it. The spraying method of the present invention is preferably a method in which the additive for the hydraulic composition of the present invention and a hydraulic composition containing water, hydraulic powder, and aggregate are each pumped under air pressure and mixed, and the resulting hydraulic composition for spraying is sprayed onto the target surface. The additive for hydraulic compositions of the present invention may be mixed with the hydraulic composition after the hydraulic composition has been manufactured by mixing water, hydraulic powder, and aggregate, using a mixer. Alternatively, the additive for hydraulic compositions of the present invention and the hydraulic composition may be separately pumped and then combined for mixing. From the viewpoint of suppressing sludge, it is preferable to separately pump the additive for hydraulic compositions of the present invention and the hydraulic composition and then combine for mixing.

[0087] In the spraying method of the present invention, when the hydraulic composition of the present invention is sprayed onto a target surface by air pressure, the air pressure used to spray the hydraulic composition onto the target surface is preferably 0.2 MPa or higher, more preferably 0.3 MPa or higher, even more preferably 0.4 MPa or higher, from the viewpoint of slag suppression and discharge workability, and preferably 1.2 MPa or lower, more preferably 1.0 MPa or lower, even more preferably 0.8 MPa or lower, and even more preferably 0.6 MPa or lower, from the viewpoint of slag suppression. It is preferable that the pressure used to air-feed the hydraulic composition of the present invention is within the above range.

[0088] In the spraying method of the present invention, from the viewpoint of more fully experiencing the effects of the present invention, the hydraulic composition of the present invention is sprayed onto the target surface in an environment where the humidity is preferably 80% RH or higher, more preferably 85% RH or higher, even more preferably 90% RH or higher, and preferably 100% RH or lower. Under the above-mentioned humidity of 80% RH or higher, the additive for the hydraulic composition of the present invention will absorb moisture, increasing its water content. However, in the spraying method of the present invention, even under such conditions, the generation of slag can be suppressed by using the additive for the hydraulic composition of the present invention.

[0089] The spraying method of the present invention will be described in detail with specific examples. However, the spraying method of the present invention is not limited in any way to these specific examples. In the spraying method of the present invention, a hydraulic composition is first produced by mixing hydraulic powder, aggregate, and water. A hydraulic composition produced by mixing hydraulic powder, aggregate, and water, and furthermore, the hydraulic composition of the present invention, has a water / hydraulic powder ratio (W / C) [mass percentage of water and hydraulic powder in the hydraulic composition] which, from the viewpoint of suppressing slag, is preferably 30% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0090] In the present invention, the mixing of hydraulic powder, aggregate, water, and other optional components can be carried out by known methods. For example, a method of simultaneously mixing hydraulic powder, water, and aggregate can be used. Mixing mixers such as pan-type forced mixers, twin-screw forced mixers, and tiltable mixers can be used to mix these components.

[0091] In the present invention, a hydraulic composition for spraying can be produced by mixing a hydraulic powder, aggregate, and water to obtain a hydraulic composition, and then mixing the hydraulic composition additive of the present invention and optionally a rapid setting agent with this hydraulic composition. The mixing of the hydraulic composition and the hydraulic composition additive and / or rapid setting agent of the present invention can be carried out, for example, by a general spraying method in which the hydraulic composition and the hydraulic composition additive and / or rapid setting agent of the present invention are pneumatically fed and mixed together.

[0092] In the present invention, the additive for hydraulic compositions of the present invention is mixed with the hydraulic powder in the hydraulic composition in an amount preferably of 0.1% by mass or more, more preferably of 0.2% by mass or more, even more preferably of 0.5% by mass or more, and preferably of 10% by mass or less, more preferably of 5.0% by mass or less, and even more preferably of 3.0% by mass or less, from the viewpoint of suppressing slag formation.

[0093] In the present invention, when the rapid setting agent is used, the rapid setting agent is mixed with 100 parts by mass of the hydraulic powder in the hydraulic composition in an amount of preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, even more preferably 7 parts by mass or more, and preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, from the viewpoint of suppressing slag and developing strength.

[0094] Furthermore, the spraying method of the present invention may optionally use the aforementioned dispersant. When a dispersant is used in the spraying method of the present invention, the dispersant may be mixed with water in advance during the process of preparing the hydraulic composition. In the present invention, when the dispersant is used, the dispersant is mixed with 100 parts by mass of hydraulic powder in the hydraulic composition in an amount of preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.07 parts by mass or more, and preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less, from the viewpoint of discharge workability and slag suppression.

[0095] In the spraying method of the present invention, the hydraulic composition for spraying prepared in this manner is sprayed onto the target object. The spraying method of the present invention can be implemented using conventional spraying equipment. The spraying equipment only needs to be able to perform spraying without any problems. For example, it is possible to use Arriba Corporation's "Arriba 280" or the like for pumping the hydraulic composition, and Chiyoda Seisakusho Co., Ltd.'s "Natomcrete" or the like for pumping the additive and / or quick-setting agent for the hydraulic composition of the present invention, mix the two to prepare the hydraulic composition, and then spray it. [Examples]

[0096] In the examples and comparative examples, the additives for hydraulic compositions shown in Table 1 were prepared using components (A) and (B) below. Hydraulic compositions were then prepared using these additives, and the rate of slag generation was evaluated. The results are shown in Table 1.

[0097] <(A) component> • Smecton SA: Synthetic saponite, manufactured by Kunimine Industries Co., Ltd., swelling degree 45 mL / 2 g, average particle size 47.8 μm, smectite content 100% by mass <(B) component> • Talc: Manufactured by Fujifilm Wako Pure Chemical Industries, average particle size 55.8 μm, average aspect ratio 1.33

[0098] <Measurement of swelling degree> (A) The degree of swelling of component (A) was measured according to the swelling test method for bentonite (powder) specified in JBAS104:77 of the Japan Bentonite Industry Association. Specifically, 2.0 g of the sample, adjusted to a moisture content of 8.0% by mass, was added in approximately 10 portions to a 100 mL stoppered graduated cylinder containing 100 mL of distilled water. At this time, the next addition was made only after the previous addition had settled at the bottom of the graduated cylinder. After standing for 24 hours, the apparent volume of the sample mass at the bottom of the graduated cylinder that had swollen was read from the scale of the graduated cylinder and defined as the degree of swelling (mL / 2g).

[0099] <(A) Method for measuring the smectite content> (i)Drying (A) The component was placed in a hot air dryer and dried at 105°C for 1 hour. (ii) Measurement of methylene blue adsorption The amount of methylene blue adsorbed by the clay mineral of component (A) was measured according to the following method in accordance with the Japanese Industrial Standard (JIS Z 2451:2019). 1.87 g of methylene blue (molecular weight 374, Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 500 mL of deionized water to prepare a 10 mmol / L aqueous solution of methylene blue. In addition, 1.68 g of sodium pyrophosphate decahydrate (molecular weight 446, Sigma-Aldrich) was dissolved in 500 mL of deionized water to prepare a 0.2% by mass aqueous solution of sodium pyrophosphate. <Reagents> 10 mmol / L aqueous solution of methylene blue (molecular weight 374) 0.2% by mass aqueous solution of sodium pyrophosphate (Na4P2O7) <How to operate> Approximately 0.4 g of component (A) was placed in a 100 mL screw-cap tube, and 40 g of a 0.2% by mass aqueous solution of sodium pyrophosphate was added to it. This mixture was dispersed in an ultrasonic cleaner (ASUCLEANER, ASU-3, AS ONE Corporation) for 30 minutes, and then heated in 80°C hot water for 30 minutes. A 10 mmol / L methylene blue aqueous solution was added dropwise to the dispersed mixture while stirring with a magnetic stirrer. After each drop, a portion of the supernatant was drawn up using a glass Pasteur pipette and added to filter paper. The supernatant was added in an amount sufficient to form a spot approximately 10 mm in diameter on the filter paper. This procedure was repeated until a halo was observed around the spot. Once the halo was observed, the titration was terminated when the width of the halo exceeded 2 mm. Then, based on the mass of component (A) and the total amount of 10 mmol / L aqueous methylene blue solution added dropwise to the endpoint, the amount of methylene blue adsorbed per 100 g of component (A) was calculated. Specifically, the product of the titration volume (L) and the concentration of the methylene blue aqueous solution (10 mmol / L) was converted to a value per 100 g of component (A) to calculate the total amount of methylene blue adsorbed (mmol). (iii) Calculation of smectite content A saturation adsorption amount of methylene blue for smectite was set at 140 mmol / 100g. The smectite content of component (A) was calculated by dividing this saturation adsorption amount by the measured methylene blue adsorption amount of component (A) and multiplying by 100. The smectite content of component (A) was the same as the mass of component (A) used in the preparation of the additive for the hydraulic composition. Therefore, the smectite content of component (A) was 100% by mass.

[0100] <Method for measuring average particle size> For components (A) and (B), the arithmetic mean particle size was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920 (manufactured by Horiba, Ltd.)) with ethanol (purity 99.5%) as the dispersion medium and ultrasound applied for 1 minute.

[0101] <Method for measuring the proportion of particles with an aspect ratio of 1 or more and less than 10 among all particles of component (B), and the average value of the aspect ratio of component (B)> (B) 1 g of component and 100 g of water were mixed to prepare an aqueous dispersion of component (B). The aqueous dispersion of component (B) was placed between a slide glass and a cover glass and photographed using a digital microscope (DSX1000, manufactured by OLYMPUS Corporation, 200x magnification) in the simplified deflection mode. 100 particles were randomly selected from the obtained image, and the long axis and short axis of each particle were measured. The aspect ratio of each particle was calculated from the long axis and short axis measured for each particle, and the proportion of particles with an aspect ratio of 1 or more and less than 10 among all selected particles was calculated based on the number of particles with an aspect ratio of 1 or more and less than 10. The calculated number percentages are shown in Table 1 as the number percentage of particles with an aspect ratio of 1 or more and less than 10 among all particles of component (B). The number percentage of particles with an aspect ratio of 1 or more and 4 among all particles of component (B) was the same as the number percentages shown in Table 1. Furthermore, the average aspect ratio of all selected particles was calculated and used as the average aspect ratio of component (B). The average aspect ratio of component (B) was 1.33.

[0102] <Method for producing additives for hydraulic compositions> Components (A) and (B) were placed in 250 mL sealed bottles in the proportions shown in Table 1, and the bottles were mixed by manually shaking them while repeatedly inverting the bottle for 60 seconds to produce the hydraulic composition additives shown in Table 1.

[0103] <Moisture absorption test> The additives for the hydraulic composition were either stored in advance under a humidity atmosphere of 60% relative humidity, or dried in a hot air dryer at 105°C for 1 hour. First, a saturated potassium chloride aqueous solution was placed in a container for storing the additive for the hydraulic composition, and the humidity inside the container was maintained at 85% RH. Then, a cup containing the additive for the hydraulic composition was left undisturbed in the container with the humidity maintained at 85% RH for 120 hours. During this time, the cup was placed in the container so that the additive for the hydraulic composition did not come into contact with the saturated potassium chloride aqueous solution. The water content of the additives for hydraulic compositions was measured before and after the moisture absorption test using the following method, and the rate of slag generation was evaluated using each of the hydraulic composition additives. The results are shown in Table 1.

[0104] <Method for measuring the water content of additives for hydraulic compositions> Approximately 2 g of the hydraulic composition additive from Table 1 was measured into an aluminum cup and dried in a hot air dryer at 105°C for 1 hour. The water content of the hydraulic composition additive was calculated by dividing the loss during drying by the mass of the hydraulic composition additive measured before drying.

[0105] <Method for measuring norovirus outbreak rates> (1) Preparation of hydraulic composition A mortar mixer as specified in "JIS R 5201 Physical Testing Methods for Cement" was used to prepare the hydraulic composition. The following water, cement, and fine aggregate were used in the preparation of the hydraulic composition. Water (W): Tap water Cement (C): Ordinary Portland cement (two-component mixture: Taiheiyo Cement / Sumitomo Osaka Cement = 1 / 1, mass ratio) Density 3.16 g / cm³3 Fine aggregate (S): Joyo mountain sand density 2.55g / cm 3

[0106] 240g of water, 400g of cement, and 1054g of fine aggregate were added to the mixing bowl of a mortar mixer and stirred at low speed for 2 minutes. 4g of the hydraulic composition additives listed in Table 1 were added to the resulting mortar and stirred by hand for 5 seconds. The water used for mixing was at 0°C, and the other materials were at 20°C, resulting in a hydraulic composition with a temperature of 15-17°C.

[0107] (2) Method for measuring norovirus 1500 g of the hydraulic composition obtained in (1) above was sprayed onto a wooden board 18 cm away from the discharge port of a powder and granular material conveying device (Breath Slider, model number K-40, manufactured by Breath Co., Ltd.). The pressure of the compressor connected to the powder and granular material conveying device was 0.6 MPa, and the inner diameter d of the discharge port was 3.5 cm. The height of the discharge port of the jet-to-conveyor device was 22 cm above the bottom of the wooden board, and the hydraulic composition was sprayed horizontally onto the vertically positioned wooden board.

[0108] In the case of hydraulic compositions sprayed onto wooden boards, those that did not generate slag adhered only to the sprayed areas and formed a laminate. On the other hand, in the case that generated slag, it was observed that the paste component of the hydraulic composition and a small amount of fine aggregate flowed down directly below the sprayed area. The mass of the hydraulic composition that fell directly below the wooden board and the mass of the hydraulic composition that adhered to the lower end of the wooden board and the portion 8 cm above the lower end (i.e., the component that flowed down to the lower part of the sprayed area and adhered to the lower end of the wooden board and the portion 8 cm above the lower end) were measured, and the slag generation rate (mass %) was calculated using the following formula (1). The lower this slag generation rate, the more effectively slag generation is suppressed when the hydraulic composition is sprayed. Slag generation rate (mass %) = 100 × [(mass of hydraulic composition that fell directly below the wooden board) + (mass of hydraulic composition that adhered to the lower edge of the wooden board and the area between the lower edge and 8 cm above it)] / (total mass of sprayed hydraulic composition) (1)

[0109] Table 1

Claims

1. An additive for hydraulic compositions, comprising (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more.

2. The additive for hydraulic compositions according to claim 1 or 2, wherein the water content in the additive is 0% by mass or more and 25% by mass or less.

3. The additive for hydraulic compositions according to claim 1 or 2, wherein the swelling degree of component (A) is 30 mL / 2 g or more.

4. The additive for hydraulic compositions according to claim 1 or 2, wherein the average particle size of component (A) is 0.01 μm or more and 500 μm or less.

5. The additive for hydraulic compositions according to claim 1 or 2, wherein the average particle size of component (B) is 0.01 μm or more and 500 μm or less.

6. The particle size ratio (r) of the average particle size of component (A) and the average particle size of component (B) Ａ / r Ｂ The additive for hydraulic compositions according to claim 1 or 2, wherein the value of ) is 0.001 or more and 1000 or less.

7. An additive for a hydraulic composition according to claim 1 or 2, comprising a rapid setting agent.

8. A method for producing an additive for a hydraulic composition, comprising the step of mixing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio [(A) / (B)] of the amount of the mixed component (A) to the amount of the mixed component (B) is 0.5 or more.

9. A hydraulic composition comprising: (A) a smectite-type clay mineral; (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the additive for hydraulic compositions has a mass ratio [(A) / (B)] of the content of component (A) to the content of component (B) of 0.5 or more; hydraulic powder; and water.

10. A hydraulic composition comprising an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, a hydraulic powder, and water.

11. A method for producing a hydraulic composition, comprising mixing an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, a hydraulic powder, and water.

12. A spraying method comprising mixing a hydraulic composition containing hydraulic powder and water with an additive for hydraulic compositions containing (A) a smectite-type clay mineral and (B) magnesium silicate having an aspect ratio of 1 or more and less than 10, wherein the mass ratio of the content of component (A) to the content of component (B) [(A) / (B)] is 0.5 or more, and spraying the mixture onto an object.

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