Spray hydraulic composition

Abstract

To provide a spray hydraulic composition that improves the productivity of spraying work of a wet type spraying method employing a hydraulic composition.SOLUTION: The spray hydraulic composition is constituted of an admixture of hydraulic powder, clay mineral, and water containing not less than 60 ppm and not more than 750 ppm of a trivalent metal ion.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a hydraulic composition for spraying and a wet spraying method using the hydraulic composition for spraying. [Background technology]

[0002] In order to prevent the collapse of exposed ground such as during tunnel excavation, a spraying method using quick-setting concrete, which is made by mixing an accelerator with concrete, is being used. Among these methods, the wet spraying method is usually carried out by preparing the shotcrete in a cement, aggregate and water metered mixing plant installed at the excavation site, and then transporting it to the transport / spraying machine with an agitator truck. The concrete and powdered quick-setting agent are mixed in a line that pneumatically pumps the concrete to the discharge port of the spraying machine, and a junction pipe is installed midway between the line and a line that pneumatically pumps the powdered quick-setting agent from the other side, and the mixture is sprayed onto the ground surface until it reaches the specified thickness as quick-setting shotcrete.

[0003] Patent Document 1 discloses a bentonite-blended shotcrete made of a mixture of cement, bentonite, fine aggregate, and water, in which the ratio of the mass of bentonite to the mass of cement is 20% by mass or less. It also discloses that this bentonite-blended shotcrete suppresses dust generation and reduces rebound during spraying. Patent Document 2 discloses a slump-reducing spray admixture that contains a clay mineral and an aluminum-containing substance. It also discloses that this slump-reducing spray admixture can significantly reduce the slump of cement concrete when sprayed, prevent sagging, and adjust the hardness to an appropriate level for trowel finishing. Patent Document 3 discloses an additive for a hydraulic composition to be sprayed, which contains (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 types of accelerators selected from a cement mineral-based accelerator and an aluminum-based accelerator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-026598 A [Patent Document 2] JP 2001-322850 A [Patent Document 3] Patent Publication No. 2021-070611 Summary of the Invention [Problem to be solved by the invention]

[0005] If the spray hydraulic composition spreads from the sprayed site when it is sprayed onto an object, it may take a long time to layer the spray hydraulic composition, resulting in a decrease in work efficiency. The present invention provides a hydraulic composition for spraying and a wet spraying method which, when sprayed, suppresses the spread of the composition from the sprayed site and improves the productivity of the spraying work. [Means for solving the problem]

[0006] The present invention relates to a hydraulic composition for spraying, which is obtained by blending hydraulic powder, a clay mineral, and water containing 60 ppm or more and 750 ppm or less of trivalent metal ions.

[0007] The present invention also relates to a wet spraying method in which a hydraulic composition for spraying, which is prepared by mixing hydraulic powder, a clay mineral, and water containing 60 ppm to 750 ppm of trivalent metal ions, is sprayed onto an object. Effect of the Invention

[0008] According to the present invention, there are provided a hydraulic composition for spraying and a wet spraying method which, when the hydraulic composition for spraying is sprayed, suppresses the spread of the composition from the sprayed site and improves the productivity of the spraying work. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The reason why the sprayable hydraulic composition of the present invention is able to suppress the spreading of the composition from the sprayed site is not entirely clear, but is presumed to be as follows. Generally, polyvalent metal ions aggregate clay minerals and reduce the thickening effect, so that the sprayed hydraulic composition is likely to spread thinly. In the present invention, it is presumed that by kneading trivalent metal ions into the hydraulic composition in advance at a specific concentration, the hydraulic powder and clay minerals strongly interact with each other, increasing the cohesion of the spray hydraulic composition, and suppressing the spread of the composition from the sprayed area when the spray hydraulic composition is sprayed on an object. On the other hand, it is presumed that if the concentration of trivalent metal ions becomes too high, the clay minerals aggregate, reducing the effect of suppressing the spread, and the hydraulic composition spreads more at the sprayed area. The hydraulic composition for spraying and the wet spraying method of the present invention are not limited to the above-mentioned mechanism of action.

[0010] <Hydraulic composition for spraying> The spray hydraulic composition of the present invention is a mixture of hydraulic powder, clay mineral, and water containing 60 ppm to 750 ppm of trivalent metal ions. Unless otherwise specified, the water described as a compounding component of the spray hydraulic composition of the present invention is water containing 60 ppm to 750 ppm of trivalent metal ions. Furthermore, the provisions regarding the contents of each component contained in the hydraulic composition for spraying of the present invention can be applied by replacing them with the blending amounts of each component in the hydraulic composition.

[0011] The hydraulic powder used in the sprayable hydraulic composition of the present invention is a powder that hardens when mixed with water, and examples thereof include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, moderate-heat Portland cement, white Portland cement, and ecocement (e.g., JIS R5214, etc.). Among these, from the viewpoint of the spread of the sprayable hydraulic composition, cement selected from early-early-strength Portland cement, ordinary Portland cement, sulfate-resistant Portland cement, and white Portland cement is preferred, and early-early-strength Portland cement and ordinary Portland cement are more preferred.

[0012] The hydraulic powder may include blast furnace slag, fly ash, silica fume, anhydrous gypsum, etc., and may also include non-hydraulic limestone fine powder, etc. As the hydraulic powder, blast furnace cement, fly ash cement, or silica fume cement, which is a mixture of cement with blast furnace slag, fly ash, silica fume, etc., may also be used.

[0013] The spray hydraulic composition of the present invention preferably contains aggregate. Examples of the aggregate include aggregates selected from fine aggregates and coarse aggregates. The aggregate preferably contains fine aggregate. Examples of the fine aggregate include those specified by number 2311 in JIS A0203-2014. Examples of the fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand and crushed sands thereof, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate. Examples of the coarse aggregate include those specified by number 2312 in JIS A0203-2014. For example, examples of the coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate. The fine aggregate and the coarse aggregate may be used in a mixture of different types, or a single type may be used. The sprayable hydraulic composition of the present invention preferably contains fine aggregate as an aggregate. The amount of fine aggregate used in the sprayable hydraulic composition of the present invention is preferably 800 kg / m 3 More preferably, 900kg / m 3 More than 1300 kg / m 3 Less than or equal to 1200 kg / m 3 The following is the result. In the sprayable hydraulic composition of the present invention, the fine aggregate ratio is preferably 35% or more, more preferably 45% or more, and preferably 70% or less, more preferably 65% ​​or less. Here, the fine aggregate ratio is the volume content of fine aggregate in the total aggregate.

[0014] The water / hydraulic powder ratio (W / C) of the sprayable hydraulic composition of the present invention is, from the viewpoint of the spread of the sprayable hydraulic composition, preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less. That is, from the viewpoint of spreading of the hydraulic composition for spraying of the present invention, the hydraulic composition for spraying contains water in an amount of preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 65 parts by mass or less, relative to 100 parts by mass of the hydraulic powder. The water / hydraulic powder ratio (W / C) is the mass percentage (mass%) of water and hydraulic powder in the spray hydraulic composition, and is calculated as (water / hydraulic powder)×100. In addition, when the hydraulic powder includes powders selected from powders having pozzolanic action, powders having latent hydraulic properties, and stone powder (calcium carbonate powder) in addition to powders having properties that harden through hydration reactions such as cement, the amounts of these powders are also included in the amount of hydraulic powder in the present invention. In addition, when 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. This also applies to other parts by mass that are related to the mass of the hydraulic powder.

[0015] The sprayable hydraulic composition of the present invention contains a clay mineral, which is preferably a clay mineral having a swelling degree of 15 mL / 2 g or more and 50 mL / 2 g or less from the viewpoint of the spreadability of the sprayable hydraulic composition.

[0016] From the viewpoint of spreading of the sprayable hydraulic composition, the swelling degree of the clay mineral is 15 mL / 2 g or more, preferably 20 mL / 2 g or more, and 50 mL / 2 g or less, preferably 45 mL / 2 g or less, more preferably 40 mL / 2 g or less. This degree of swelling is measured according to the swelling test method for bentonite (powdered) in JBAS104:77 of the Japan Bentonite Industry Association. That is, 2.0 g of sample adjusted to 8.0% moisture by mass is added in about 10 separate additions to a 100 ml stoppered measuring cylinder containing 100 ml of distilled water. The next addition is made after the previous addition has settled to the bottom of the measuring cylinder. After leaving it for 24 hours, the apparent volume of the swollen sample mass at the bottom of the measuring cylinder is read from the graduations on the measuring cylinder and expressed as the degree of swelling (mL / 2 g).

[0017] The clay mineral may be a cation-exchangeable layered silicate. One example of such a clay mineral may be one or more clay minerals selected from smectite and bentonite. Smectite is a group of cation-exchangeable layered silicates belonging to clay minerals, and natural products include montmorillonite, which is well known as the main component of bentonite, as well as beidellite, hectorite, saponite, nontronite, etc., and synthetic products include swelling fluorine-based micas, etc. Among these, the clay mineral contained in the spray hydraulic composition of the present invention is preferably a clay mineral selected from bentonite, saponite, hectorite, and montmorillonite, more preferably a clay mineral selected from bentonite and montmorillonite, and even more preferably bentonite, from the viewpoint of the spread of the spray hydraulic composition. The content of the clay mineral selected from bentonite, saponite, hectorite and montmorillonite in the clay minerals contained in the hydraulic composition for spraying is preferably 60 mass% or more, more preferably 100 mass%, and further preferably the content of bentonite is 100 mass%.

[0018] The hydraulic composition for spraying of the present invention contains a clay mineral in an amount of preferably 0.02% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, from the viewpoints of spreadability and ejection workability of the hydraulic composition for spraying.

[0019] The hydraulic composition for spraying of the present invention contains a clay mineral in an amount of preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, even more preferably 0.5 part by mass or more, and preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the hydraulic powder contained in the hydraulic composition for spraying, from the viewpoint of spread of the hydraulic composition for spraying.

[0020] The hydraulic composition for spraying of the present invention contains water. The water contains 60 ppm or more and 750 ppm or less of trivalent metal ions. The trivalent metal ion may be one or more selected from the group consisting of trivalent iron ion, trivalent aluminum ion, trivalent chromium ion, trivalent gallium ion, trivalent indium ion, trivalent thallium ion, trivalent bismuth ion, trivalent lanthanum ion, and trivalent rare earth ion. The trivalent metal ion is preferably a trivalent iron ion from the viewpoint of discharge workability. Furthermore, the trivalent metal ion is preferably a trivalent aluminum ion from the viewpoint of reducing the spread of the spray hydraulic composition at a low concentration. From the above viewpoint, the trivalent metal ion is preferably one or more selected from the group consisting of a trivalent iron ion and a trivalent aluminum ion.

[0021] From the viewpoint of spreading of the sprayable hydraulic composition, the concentration of trivalent metal ions in the water is 60 ppm or more, preferably 75 ppm or more, more preferably 100 ppm or more, even more preferably 150 ppm or more, still more preferably 200 ppm or more, and is 750 ppm or less, preferably 600 ppm or less, more preferably 500 ppm or less, and even more preferably 400 ppm or less.

[0022] The concentration of trivalent metal ions in water can be measured, for example, using a digital pack test made by Kyoritsu Rikagaku Kenkyusho Co., Ltd. The concentration of trivalent iron ions can be measured using a digital pack test (model WAK-Fe 3+ The trivalent aluminum ion can be measured by the ECR method of the Digital Pack Test (type LR-Al).

[0023] <Accelerating agent> The sprayable hydraulic composition of the present invention may optionally contain an accelerator. The accelerator is preferably a powder accelerator. The accelerator is, for example, one or more accelerators selected from a cement mineral-based accelerator and an aluminum-based accelerator.

[0024] The cement mineral-based quick-setting admixture may be at least one selected from calcium aluminate, calcium sulfoaluminate, and calcium aluminate. The aluminum-based quick-setting admixture may be at least one selected from aluminum salts including 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 spread of the spray hydraulic composition, the quick-setting admixture 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.

[0025] In the spray hydraulic composition of the present invention, an additive for spray hydraulic composition (hereinafter referred to as the additive of the present invention), which is a mixture of the above clay mineral and quick-setting agent, may be used. The additive is mixed with the hydraulic composition containing hydraulic powder and water when the spray hydraulic composition is sprayed. The additive of the present invention contains a quick-setting admixture in an amount of preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 98% by mass or less, more preferably 96% by mass or less, even more preferably 95% by mass or less, from the viewpoint of spread of the hydraulic composition for spraying.

[0026] In the additive of the present invention, the mass ratio of the content of the clay mineral to the content of the quick-setting admixture, (quick-setting admixture) / (clay mineral), from the viewpoints of discharge workability and the amount of dust, is preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and is preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less.

[0027] When the hydraulic composition for spraying of the present invention contains a quick-setting admixture, the hydraulic composition for spraying of the present invention contains the quick-setting admixture in an amount of preferably 4 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 6.5 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the hydraulic powder contained in the hydraulic composition for spraying, from the viewpoints of the spreadability, strength expression and ejection workability of the hydraulic composition for spraying.

[0028] When the sprayable hydraulic composition of the present invention contains a quick-setting admixture, the mass ratio of the content of the clay mineral to the content of the quick-setting admixture in the sprayable hydraulic composition of the present invention (quick-setting admixture) / (clay mineral) is preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and is preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less, from the viewpoints of spreadability and strength development of the sprayable hydraulic composition.

[0029] The hydraulic composition for spraying of the present invention may contain, as necessary, one or more of 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 expansive 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, an efflorescence inhibitor, a thickener, etc.

[0030] <Wet spraying method> The present invention provides a wet spraying method in which a hydraulic composition for spraying, which is prepared by mixing hydraulic powder, a clay mineral, and water containing 60 ppm to 750 ppm of trivalent metal ions, is sprayed onto an object. The present invention also provides a wet spraying method, which comprises mixing a hydraulic powder with water containing 60 ppm or more and 750 ppm or less of trivalent metal ions to produce a hydraulic composition for spraying by mixing a clay mineral with the hydraulic composition, and spraying the hydraulic composition for spraying onto an object. In the wet spraying method of the present invention, the hydraulic composition or the hydraulic composition for spraying may be mixed with an accelerator, and the hydraulic composition or the hydraulic composition for spraying mixed with the accelerator may be sprayed onto an object. In the wet spraying method of the present invention, the hydraulic powder, clay mineral, water containing trivalent metal ions and quick-setting admixture are the same as those described in the hydraulic composition for spraying of the present invention. As a preferred embodiment in the wet spraying method of the present invention, the embodiment described in the hydraulic composition for spraying of the present invention can be appropriately applied.

[0031] The wet spraying method of the present invention will be described in detail with reference to a specific example, but the wet spraying method of the present invention is not limited to this specific example. In the wet spraying method of the present invention, first, hydraulic powder, water, and optionally aggregate are mixed to produce a hydraulic composition. The hydraulic composition produced by mixing hydraulic powder, water and optionally aggregate has a water / hydraulic powder ratio (W / C) [the mass percentage (mass%) of water and hydraulic powder in the hydraulic composition] of preferably 30 mass% or more, more preferably 40 mass% or more, even more preferably 50 mass% or more, and preferably 80 mass% or less, more preferably 70 mass% or less, even more preferably 65 mass% or less, from the viewpoint of the spreadability and discharge workability of the hydraulic composition for spraying. Usually, the water / hydraulic powder ratio of the hydraulic composition is reflected in the hydraulic composition for spraying produced subsequently. Therefore, in the present invention, the water / hydraulic powder ratio of the hydraulic composition for spraying is also preferably within the above range.

[0032] In the present invention, the mixing of optional components such as hydraulic powder, water, and aggregate can be carried out by a known method. Specifically, a method of simultaneously mixing hydraulic powder, water, and aggregate can be mentioned. To mix these components, a mixing mixer such as a pan-type forced mixer, a two-shaft forced mixer, or a tilting mixer can be used.

[0033] In the present invention, the above clay mineral and the above quick-setting agent are added to a hydraulic composition obtained by mixing hydraulic powder, water, and any aggregate to produce a sprayable hydraulic composition. The mixing of the hydraulic composition, the clay mineral, and the quick-setting agent can be carried out, for example, by a general wet spraying method in which the hydraulic composition, the clay mineral, and the quick-setting agent are separately pneumatically pumped and then mixed together. It is also preferable that the clay mineral and the quick-setting agent are mixed in advance and then mixed with the hydraulic composition. The mixture of the clay mineral and the quick-setting agent may be the additive for the sprayable hydraulic composition of the present invention. In the present invention, a hydraulic composition can be produced by mixing optional components such as hydraulic powder, clay mineral, water and aggregate, and adding a quick-setting agent to the hydraulic composition to produce a hydraulic composition for spraying.

[0034] In the present invention, the clay mineral is mixed in an amount of preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, even more preferably 0.5 part by mass or more, and preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, even more preferably 2 parts by mass or less, per 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoint of the spread of the spray hydraulic composition.

[0035] In the present invention, when the quick-setting admixture is used, the quick-setting admixture is mixed in an amount of preferably 4 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 6.5 parts by mass or more, still more preferably 7 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the hydraulic powder in the hydraulic composition, from the viewpoints of spreadability, strength expression and ejection workability of the hydraulic composition for spraying.

[0036] In the present invention, when the quick-setting admixture is used, the mass ratio of the amount of the clay mineral mixed to the amount of the quick-setting admixture (quick-setting admixture) / (clay mineral) is, from the viewpoint of spreadability and strength development of the sprayable hydraulic composition, preferably 3 or more, more preferably 4 or more, even more preferably 4.5 or more, and preferably 90 or less, more preferably 50 or less, even more preferably 25 or less, still more preferably 20 or less, still more preferably 18 or less, and even more preferably 15 or less.

[0037] In the spraying method of the present invention, the thus prepared hydraulic composition for spraying is sprayed onto an object, which corresponds to the so-called wet spraying method. The wet spraying method of the present invention can be carried out by using conventional spraying equipment. The spraying equipment may be any equipment that can perform wet spraying without any problems, and for example, Arriba 280 (trade name) or the like manufactured by Arriba Corporation may be used to pump the hydraulic composition, and Natomcrete (trade name) or the like manufactured by Chiyoda Seisakusho may be used to pump the mixture of clay mineral and quick-setting agent, and the two may be mixed to prepare a hydraulic composition for spraying, which may then be sprayed. EXAMPLES

[0038] The components in the table are as follows: <Clay minerals> Clay minerals: Bentonite, Kunigel GS, manufactured by Kunimine Kogyo Co., Ltd., swelling degree 33mL / 2g

[0039] The swelling degree of clay minerals was measured according to the swelling test method for bentonite (powdered) in JBAS104:77 of the Japan Bentonite Industry Association. That is, 2.0 g of sample adjusted to 8.0 mass% moisture was added in about 10 separate portions to a 100 ml stoppered measuring cylinder containing 100 ml of distilled water. The next addition was made after the previous addition had settled at the bottom of the measuring cylinder. After leaving it for 24 hours, the apparent volume of the swollen sample mass at the bottom of the measuring cylinder was read from the graduations on the measuring cylinder and was taken as the swelling degree (mL / 2 g).

[0040] (1) Preparation of hydraulic composition The hydraulic composition had the following ingredients: The water was prepared by dissolving iron (III) chloride or aluminum (III) sulfate in tap water so that the trivalent iron ion and trivalent aluminum ion concentrations were as shown in Table 1. When the iron ion concentration in the water was measured using a digital pack test (model WAK-Fe3+) made by Kyoritsu Rikagaku Kenkyusho Co., Ltd., the tap water was found to be below the detection limit of 1 ppm. In addition, solutions prepared by dissolving iron (III) chloride in tap water were found to have concentrations of 50, 101, 203, and 564,976 ppm, respectively. At this time, the 101, 203, and 564,976 ppm solutions exceeded the detection limit, so they were diluted to concentrations below the detection limit of 50 ppm and measured. In addition, when the aluminum ion concentration of water was measured using a digital pack test (model LR-Al) manufactured by Kyoritsu Rikagaku Kenkyusho Co., Ltd., the tap water was found to be below the detection limit of 0.05 ppm. In addition, an aqueous solution prepared by dissolving aluminum sulfate (III) in tap water was found to have concentrations of 65 and 102 ppm. At this time, the 65 and 102 ppm aqueous solutions exceeded the detection limit, so they were diluted to concentrations below the detection limit of 0.40 ppm and then measured.

[0041] <Components of hydraulic composition> Water: Water containing Fe(III) ions or Al(III) ions at the concentrations in Table 1, prepared by the method described above. Cement (hydraulic powder): A 1:1 mixture of ordinary Portland cement manufactured by Taiheiyo Cement Corporation and ordinary Portland cement manufactured by Sumitomo Osaka Cement Corporation. Aggregate (sand): Mountain sand from Joyo City, Kyoto Prefecture Surface-dried specific gravity: 2.55 Clay minerals: Bentonite, Kunigel GS, manufactured by Kunimine Kogyo Co., Ltd. Swelling degree 33mL / 2g

[0042] The hydraulic composition was prepared using a mortar mixer as specified in "JIS R 5201 Physical Test Methods for Cement." 240 g of water, 400 g of cement, and 1,054 g of sand were added to the mixing bowl of a mortar mixer and mixed at low speed for 2 minutes. Clay minerals were added to the resulting mortar and mixed at high speed for 10 seconds to obtain a hydraulic composition for spraying.

[0043] (2) Evaluation 1500g of the obtained spray hydraulic composition was sprayed onto a wooden board 18cm away from the nozzle of the powder / granule conveying device (Breath Rider, model number K-20, manufactured by Breath Co., Ltd.). The pressure of the compressor connected to the powder / granule conveying device was 0.6MPa, and the diameter of the nozzle was 2cm. The mass of the spray hydraulic composition attached inside a circle with a diameter of 12cm centered on the center of the spray hydraulic composition sprayed onto the wooden board and the mass of the spray hydraulic composition attached outside this circle were measured, and the spreading rate (%) was calculated by the following formula (1). It can be said that the lower the spreading rate, the more the spray hydraulic composition is suppressed from spreading from the sprayed area when sprayed. Spreading rate (%) = 100 × (mass of the spray hydraulic composition attached to the outside of a circle with a diameter of 12 cm) / (mass of the spray hydraulic composition attached to the inside of a circle with a diameter of 12 cm) (1)

[0044] [Table 1]

[0045] *Note 1: The amount of additive added is expressed as a mass percentage (mass% x C) relative to the cement (C). *Note 2: "W / C" represents the mass percentage (mass%) of water (W) to cement (C).

[0046] As shown in Table 1, the sprayable hydraulic compositions of the examples have a low spreading rate, which reduces the time required for layering the sprayable hydraulic composition and improves the efficiency of spraying the hydraulic composition.

Claims

1. A sprayable hydraulic composition comprising a hydraulic powder, a clay mineral, and water containing 60 ppm or more and 750 ppm or less of a trivalent metal ion.

2. The sprayable hydraulic composition according to Claim 1, wherein the trivalent metal ion is at least one selected from trivalent iron ions and trivalent aluminum ions.

3. The sprayable hydraulic composition according to Claim 1 or 2, wherein the clay mineral contains bentonite.

4. The sprayable hydraulic composition according to Claim 1 or 2, wherein 50 parts by mass or more and 70 parts by mass or less of the above water is blended with 100 parts by mass of the hydraulic powder.

5. The sprayable hydraulic composition according to Claim 1 or 2, wherein the swelling degree of the clay mineral is 10 mL / 2 g or more and 50 mL / 2 g or less.

6. A wet spraying method in which a sprayable hydraulic composition obtained by mixing a hydraulic powder, a clay mineral, and water containing 60 ppm or more and 750 ppm or less of a trivalent metal ion is sprayed onto an object.

7. A wet spraying method in which a clay mineral is mixed into a hydraulic composition obtained by mixing a hydraulic powder and water containing 60 ppm or more and 750 ppm or less of a trivalent metal ion to produce a sprayable hydraulic composition, and the sprayable hydraulic composition is sprayed onto an object.