Hydraulic composition

Abstract

To provide a hydraulic composition having suppressed flowability degradation even after extended kneading or stirring time in the production of a hydraulic composition using fine aggregates having a small circularity, a method for producing the same and a wet spraying method using the hydraulic composition.SOLUTION: There is provided a hydraulic composition which comprises (A) cement, (B) fine aggregates having an average circularity of 0.55 or more and 0.85 or less, (C) a polyalkylene oxide having a weight average molecular weight of 5000 or more and less than 1000000 and (D) water.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Hydraulic compositions are construction materials that are indispensable to the development of mankind, and among them, cement concrete is mainly produced by mixing cement, water, fine aggregate, and coarse aggregate, forming the mixture, and hardening the mixture. Examples of fine aggregates include natural aggregates such as river sand, land sand, mountain sand, sea sand, lime sand, and silica sand, which are defined by number 2311 in JIS A0203-2014, and artificial aggregates such as crushed sands of these, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate, and recycled fine aggregate. Natural aggregates have a relatively smooth shape with no sharp edges due to the physical action of wind and water. This reduces the adhesion and interlocking between fine aggregates, and gives the uncured hydraulic composition excellent workability (workability, fluidity). On the other hand, in recent years, the depletion of natural aggregates has become a serious problem worldwide due to population growth and economic development. As a result, the use of artificial aggregates whose particle size has been adjusted by crushing and classification has increased.

[0003] In addition, a spraying method using a hydraulic composition is used to prevent the collapse of exposed natural ground during tunnel construction, slope protection construction, etc. Among these methods, the wet spraying method is a method in which a hydraulic composition is prepared in a cement, aggregate, and water metering mix plant installed at an excavation work site, and then the hydraulic composition is transported to a transport / spraying machine by an agitator vehicle, and the hydraulic composition is sprayed from the spraying machine onto the natural ground surface until a predetermined thickness is achieved.

[0004] Patent Document 1 discloses a hydraulic composition that contains a polymer composed of structural units containing 70% by weight or more of structural units derived from 2-hydroxyethyl acrylate, a naphthalenesulfonic acid-formaldehyde condensate, hydraulic powder, fine aggregate including crushed sand, coarse aggregate, and water, and that can obtain fluidity and filling properties similar to those obtained when natural sand is used, even when aggregate including crushed sand is used. Patent Document 2 discloses a round polished aggregate and its manufacturing method, which processes aggregate (crushed stone or blast furnace slag) to give it a rounded outer shape while suppressing water absorption, thereby improving the volume ratio and reducing the unit water content when used as aggregate for concrete, thereby improving the fluidity of concrete, or so-called workability, and also improving the surface area and water permeability when used as aggregate for asphalt or roadbed material. Patent Document 3 discloses a low-dust sprayed concrete which contains a cement concrete containing polyethylene oxide and a sprayed quick-setting admixture which is substantially free of alkali metal aluminates and alkali metal hydroxides and which contains calcium aluminate and aluminum sulfate, wherein the sprayed quick-setting admixture has an aluminum sulfate content of 5 to 105 parts by mass per 100 parts by mass of the calcium aluminate and the alkaline earth metal content in the aluminum sulfate is 0.007 to 4% by mass calculated as alkaline earth metal oxide. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-173907 A [Patent Document 2] JP 2002-193646 A [Patent Document 3] International Publication No. 2022-59372 Summary of the Invention [Problem to be solved by the invention]

[0006] However, unless special processing is performed, the artificial aggregate will have sharp fracture surfaces during the crushing process to produce it, and since it is not subjected to physical effects like natural aggregate, it has a relatively "angular" shape, which can lead to problems such as a deterioration in the workability of the unhardened hydraulic composition, and the aggregate will gradually wear down and become finer during the kneading of the hydraulic composition and the stirring process in the mixer, causing a loss of workability over time.

[0007] The present invention provides a hydraulic composition in which a decrease in fluidity is suppressed even when the kneading or stirring time is extended in the production of the hydraulic composition using fine aggregate with low circularity, a production method thereof, and a wet spraying method using the hydraulic composition. [Means for solving the problem]

[0008] The present invention relates to a hydraulic composition containing (A) cement (hereinafter referred to as component (A)), (B) fine aggregate having an average circularity of 0.55 or more and 0.85 or less (hereinafter referred to as component (B)), (C) a polyalkylene oxide having a weight-average molecular weight of 5,000 or more and less than 1,000,000 (hereinafter referred to as component (C)), and (D) water (hereinafter referred to as component (D)).

[0009] The present invention also relates to a method for producing a hydraulic composition, which comprises mixing the (A) component, the (B) component, the (C) component, and the (D) component.

[0010] The present invention also relates to a wet spraying method comprising mixing the components (A), (B), (C) and (D) to produce a hydraulic composition, and spraying the hydraulic composition onto an object. Effect of the Invention

[0011] According to the present invention, in the production of a hydraulic composition using fine aggregate with low circularity, a hydraulic composition in which a decrease in fluidity is suppressed even when the kneading or stirring time is extended, a method for producing the same, and a wet spraying method using the hydraulic composition are provided.

[0012] In recent years, the SDGs have been proposed to realize a sustainable society. The present invention contributes to the conservation of natural resources and sustainable growth by improving the usefulness of fine aggregate with low circularity, and is considered to be a technology that can contribute to SDGs No. 6, 9, 11, 12, 13, 14, and 15, for example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present inventors have found that in the production of a hydraulic composition using fine aggregate with a low circularity, it is possible to provide a hydraulic composition in which the decrease in fluidity is suppressed even by extending the kneading or stirring time. The reason why such an effect is exhibited is not necessarily clear, but is presumed to be as follows. When the water-soluble polymer in an extended state in water accumulates due to shearing, it generates stress or repulsive forces between adjacent objects due to the entropy effect or osmotic pressure effect. As mentioned above, the atomization of fine aggregates with low circularity due to the extension of the kneading or stirring time of the hydraulic composition is considered to be caused by contact and wear between aggregates over time. Therefore, it is considered that the addition of the water-soluble polymer (C) of the present invention prevents the aggregates from approaching each other due to the steric repulsion effect and osmotic pressure effect, suppressing contact and wear, thereby suppressing the decrease in the workability of the slurry caused by the increase in bound water due to the increase in atomization and therefore the increase in surface area. Furthermore, as for the component (C) of the present invention, since the manifestation of the osmotic pressure effect is premised on low adsorptivity to solid surfaces (extending into the parent solvent), it is necessary that the polymer is not only hydrophilic but also has low adsorptivity to cement and fine aggregate. Furthermore, since the above-mentioned steric repulsion effect depends on the molecular chain length or weight average molecular weight of the water-soluble polymer, a certain level or more of the component (C) is necessary. On the other hand, since the above-mentioned osmotic pressure effect depends on the hydrophilicity of the water-soluble polymer, and generally the hydrophilicity of a polymer decreases as the weight average molecular weight increases, it is considered that a polyalkylene oxide having a medium molecular weight and no adsorptive functional groups is effective.

[0014] [Hydraulic composition] <Component (A)> The hydraulic composition of the present invention contains cement as component (A). Examples of cement include ordinary Portland cement, belite cement, moderate heat cement, high-early strength cement, ultra-high-early strength cement, and sulfate-resistant cement, and may also include blast furnace slag cement, fly ash cement, and silica fume cement to which blast furnace slag, fly ash, silica fume, stone powder (calcium carbonate powder), etc. have been added. One or more of these may be used.

[0015] In the hydraulic composition of the present invention, the content of component (A) is, relative to 100 parts by mass of the hydraulic composition, preferably 10 parts by mass or more, more preferably 12 parts by mass or more, and even more preferably 14 parts by mass or more from the viewpoint of the strength of the hardened body, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less from the viewpoint of suppressing cracking of the hardened body.

[0016] <(B) component> The hydraulic composition of the present invention contains, as component (B), fine aggregate having an average circularity of 0.55 or more and 0.85 or less.

[0017] The circularity of the fine aggregate of component (B) is 0.4 or more, preferably 0.45 or more, more preferably 0.50 or more, from the viewpoint of the fluidity of the hydraulic composition, and is 0.9 or less, preferably 0.85 or less, more preferably 0.83 or less, from the viewpoint of the strength of the hardened body. The average circularity of the fine aggregate of component (B) is, from the viewpoint of the fluidity of the hydraulic composition, 0.55 or more, more preferably 0.60 or more, even more preferably 0.65 or more, and still more preferably 0.70 or more, and from the viewpoint of the strength of the hardened body, 0.85 or less, more preferably 0.80 or less, and still more preferably 0.75 or less.

[0018] The circularity and average circularity of fine aggregate are calculated by the following method. 10 g of fine aggregate is sampled on a flat plate, placed in a thermostatic blower dryer (e.g., DRM620DE (Advantec Co., Ltd.)) and dried at 105 ° C for 1 hour. Then, it is cooled to room temperature, sieved through a 0.6 mm mesh sieve and a 0.3 mm mesh sieve, and the 0.3 mm mesh sieve residue is spread on a white light-emitting panel so that the particles do not come into contact with each other, and photographed in 3D at 40 times magnification using an industrial microscope (e.g., DSX1000 (Olympus Co., Ltd.)) and digitized. The photographed image is imported into the open source software ImageJ, binarized, and image analyzed. 25 particles are sampled, and the value calculated as "Circ." is the circularity. The average circularity is calculated from the average circularity of the 25 sampled particles.

[0019] Fine aggregate is defined as aggregate which passes entirely through a 10 mm sieve and at least 85% by weight through a 5 mm sieve. The fine aggregate (B) has a fine particle size fraction (FM) of preferably 1.9 or more, more preferably 2.0 or more, even more preferably 2.1 or more, and preferably 3.2 or less, more preferably 3.1 or less, even more preferably 3.0 or less, from the viewpoint of fluidity of the hydraulic composition. The fine aggregate fraction (FM) of component (B) can be measured by the method described in JIS A 1102, "Sieving test method for aggregates."

[0020] Examples of fine aggregates include those specified by number 2311 in JIS A0203-2014. Specific examples of fine aggregates include one or more selected from 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, etc. Among these, the (B) component can be one having a circularity within the above-mentioned range. From the viewpoints of availability and durability of the hydraulic composition, the fine aggregate of component (B) is preferably at least one type selected from crushed sand, river sand, land sand, and mountain sand, and more preferably crushed sand.

[0021] In the hydraulic composition of the present invention, the content of the (B) component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and preferably 90 parts by mass or less, more preferably 85 parts by mass or less, even more preferably 80 parts by mass or less, based on 100 parts by mass of the hydraulic composition, from the viewpoint of the fluidity of the hydraulic composition.

[0022] In the hydraulic composition of the present invention, the mass ratio (B) / (A) of the content of the (A) component to the content of the (B) component is preferably 2 or more, more preferably 3 or more, and even more preferably 3.5 or more, from the viewpoint of the workability of the hydraulic composition, and is preferably 6 or less, more preferably 5.5 or less, even more preferably 5 or less, and even more preferably 4.5 or less, from the viewpoint of the fluidity of the hydraulic composition.

[0023] <(C) component> The hydraulic composition of the present invention contains, as component (C), a polyalkylene oxide having a weight average molecular weight of 5,000 or more and less than 1,000,000.

[0024] The weight average molecular weight of the (C) component is, from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition, 5,000 or more, preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, still more preferably 150,000 or more, still more preferably 200,000 or more, still more preferably 250,000 or more, still more preferably 300,000 or more, and from the viewpoint of the workability of the hydraulic composition, less than 1,000,000, preferably 900,000 or less, more preferably 800,000 or less, still more preferably 700,000 or less, still more preferably 600,000 or less, still more preferably 500,000 or less, still more preferably 400,000 or less. In the case of commercially available products, the weight average molecular weight of the polyalkylene oxide may be a value based on the product information (catalog, etc.). The weight average molecular weight of the polyalkylene oxide can be determined by gel permeation chromatography (GPC) under the following measurement conditions. Measurement conditions: Equipment: Product name "LC-10AD" (manufactured by Shimadzu Corporation) Detector: Refractive index detector (RID) Column: Product name "SHODEX KF-804" (manufactured by Showa Denko K.K.) ·Measurement temperature: 30℃ ·Eluent:THF ·Flow rate: 1.0mL / min Sample concentration: 0.2% by mass (THF) Sample injection volume: 100μL Conversion standard: Polyethylene oxide

[0025] The component (C) preferably contains ethylene oxide and / or propylene oxide as polymerization units, and more preferably contains ethylene oxide. When component (C) contains ethylene oxide and propylene oxide as polymerization units, the ethylene oxide and propylene oxide may be either a random copolymer or a block copolymer. From the viewpoint of water solubility, the component (C) is preferably at least one selected from a copolymer of polyoxyethylene oxide and polypropylene oxide, and polyethylene oxide, and more preferably polyethylene oxide.

[0026] In the hydraulic composition of the present invention, the content of the (C) component is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, even more preferably 0.01 part by mass or more, and preferably 1 part by mass or less, more preferably 0.5 part by mass or less, even more preferably 0.1 part by mass or less, based on 100 parts by mass of the hydraulic composition, from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition.

[0027] In the hydraulic composition of the present invention, the content of the (C) component is 0.05 parts by mass or more, preferably 0.075 parts by mass or more, more preferably 0.10 parts by mass or more, and 1 part by mass or less, preferably 0.75 parts by mass or less, more preferably 0.50 parts by mass or less, per 100 parts by mass of the (A) component, from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition.

[0028] <(D) component> The hydraulic composition of the present invention contains water as the component (D). In the hydraulic composition of the present invention, the mass ratio (D) / (A) of the content of the (A) component to the content of the (D) component is 0.4 or more, preferably 0.45 or more, more preferably 0.5 or more, from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition, and is 0.8 or less, preferably 0.75 or less, more preferably 0.7 or less, from the viewpoint of the strength of the hardened body.

[0029] <Other ingredients, etc.> The hydraulic composition of the present invention may contain, as component (E), an aggregate other than component (B), within the range that does not impair the effects of the present invention. The component (E) may be at least one selected from fine aggregates other than the component (B) and coarse aggregates. Examples of fine aggregate include those listed under component (B), except for those that fall under component (B). Coarse aggregate is aggregate that retains 85% or more by mass on a 5 mm mesh sieve. Examples of coarse aggregate include those specified by number 2312 in JIS A0203-2014. Examples of coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, limestone gravel, crushed stones of these, blast furnace slag coarse aggregate, ferro-nickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate.

[0030] When the hydraulic composition of the present invention contains the component (E), the content of the component (E) is, from the viewpoint of the fluidity of the hydraulic composition, preferably 1 part by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, based on 100 parts by mass of the hydraulic composition.

[0031] The hydraulic composition of the present invention may contain a quick-setting admixture, but the content is limited from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition. The accelerator may be one or more selected from inorganic salt-based accelerators, cement mineral-based accelerators, and natural mineral-based accelerators. Examples of inorganic salt-based quick-setting agents include alkali metal aluminates, alkali metal carbonates, aluminum sulfate, gypsum dihydrate, gypsum hemihydrate, anhydrous gypsum, calcium chloride and silicates, calcium hydroxide, etc. Examples of cement mineral-based quick-setting agents include calcium aluminate and calcium sulfoaluminate, etc. Examples of natural mineral-based quick-setting agents include calcined alumite, etc.

[0032] In the hydraulic composition of the present invention, the content of the quick-setting admixture is preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.1 parts by mass or less, per 100 parts by mass of the (A) component, from the viewpoint of suppressing a decrease in the fluidity of the hydraulic composition. The hydraulic composition of the present invention may not contain a quick-setting admixture.

[0033] The hydraulic composition of the present invention may contain, as necessary, one or more selected from dispersants, expansion agents, hardening accelerators, hardening retarders, polymers for cement, foaming agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, pigments, fibers, water repellents, efflorescence inhibitors, etc. (excluding those corresponding to the above-mentioned components) within the scope not impairing the effects of the present invention.

[0034] The hydraulic composition of the present invention can effectively use fine aggregate with a small circularity, which is the component (B), and the decrease in fluidity is suppressed even when the kneading or stirring time is extended, so that the hydraulic composition is also optimal for the wet spraying method, in which the kneading or stirring time is often unavoidably extended due to the convenience of on-site work. That is, the hydraulic composition of the present invention is suitable for wet spraying.

[0035] The present invention may be a hydraulic composition comprising the components (A), (B), (C), and (D). The components (A), (B), (C), and (D) are the same as those described in the hydraulic composition of the present invention. The other components other than the components (A) to (D) can be blended in the hydraulic composition in the same manner. The amounts and mass ratios of each component described in the hydraulic composition of the present invention can be applied to the hydraulic composition by replacing the contents with the amounts.

[0036] [Method for producing hydraulic composition] The present invention provides a method for producing a hydraulic composition, which comprises mixing the components (A), (B), (C) and (D). The components (A), (B), (C), and (D) are the same as those described in the hydraulic composition of the present invention. The other components other than the components (A) to (D) are also the same and can be mixed in the manufacturing method of the hydraulic composition of the present invention. The mixing amount and mass ratio of each component can be applied to the manufacturing method of the hydraulic composition of the present invention by replacing the content with the mixing amount with respect to the content and mass ratio of each component described in the hydraulic composition of the present invention. The method for producing the hydraulic composition of the present invention can be appropriately applied to the aspects described for the hydraulic composition of the present invention.

[0037] In the method for producing the hydraulic composition of the present invention, the mixing of the components (A), (B), (C), and (D) can be carried out by a known method. Specifically, the components (A), (B), (C), and (D) can be mixed simultaneously. The mixing order is preferably such that the component (C) is added to the component (B), the component (A) is added and mixed, and then the component (D) is added and mixed further. A mixing mixer such as a pan-type forced mixer, a two-shaft forced mixer, or a tilting mixer can be used to mix these components.

[0038] [Wet spraying method] The present invention provides a wet spraying method comprising mixing components (A), (B), (C) and (D) to produce a hydraulic composition, and spraying the hydraulic composition onto an object.

[0039] The hydraulic composition in the wet spraying method of the present invention is the same as the hydraulic composition of the present invention, and the embodiments described in the hydraulic composition of the present invention and the manufacturing method thereof can be appropriately applied. The components (A), (B), (C), and (D) are the same as those described in the hydraulic composition of the present invention. The other components other than the components (A) to (D) are also the same and can be mixed in the method for producing the hydraulic composition. The mixing amount and mass ratio of each component can be applied to the manufacturing method of the hydraulic composition by replacing the content with the mixing amount with respect to the content and mass ratio of each component described in the hydraulic composition of the present invention.

[0040] In the spraying method of the present invention, the hydraulic composition thus prepared 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 using conventional spraying equipment. The spraying equipment may be any equipment capable of performing wet spraying without any problems, and for example, the hydraulic composition may be pumped to a spraying machine using equipment such as "Ariva 280" manufactured by Arriva, and sprayed. EXAMPLES

[0041] The components in the table are as follows: <Component (A)> A-1: Ordinary Portland cement (manufactured by Taiheiyo Cement Corporation, specific gravity 3.16)

[0042] <(B) component> B-1: Crushed sand (produced in Nishijima, Hyogo Prefecture, surface dry specific gravity 2.52, circularity: average value 0.69, minimum value 0.48, maximum value 0.82, coarse grain ratio (FM) 2.84) B-2: River sand (Ibi River, Gifu Prefecture, surface dry specific gravity 2.56, circularity: average 0.73, minimum 0.58, maximum 0.83, coarse grain ratio (FM) 2.16) <Component (B') (comparison component of component (B))> B'-1: Lunamos #50 (Kao Quaker Co., Ltd., true specific gravity 2.85, circularity: average value 0.89, minimum value 0.78, maximum value 0.93, fraction of coarse particles (FM) 2.03)

[0043] Each of the components (B) and (B') was adjusted to a surface-dried state before use in the evaluation. The circularity of each of the components (B) and (B') was calculated by the following method. 10 g of each (B) or (B') component was sampled on an aluminum flat plate, placed in a thermostatic blower dryer DRM620DE (manufactured by Advantec Co., Ltd.), and dried at 105 ° C for 1 hour. Then, it was cooled to room temperature, and sieved through a 0.6 mm mesh sieve and a 0.3 mm mesh sieve in layers, and the residue on the 0.3 mm mesh sieve was spread on a white light-emitting panel so that the particles did not come into contact with each other, and photographed in 3D at 40 times magnification using an industrial microscope DSX1000 (manufactured by Olympus Corporation) and digitized. The photographed image was imported into the open source software ImageJ, binarized, and image analyzed, 25 particles were sampled, and the value calculated as "Circ." was recorded as the circularity. In the table, the minimum, maximum, and average circularity of the 25 sampled particles for each (B) or (B') component are shown. In some of the Examples and Comparative Examples, when two types of (B) components were used, the average circularity of the (B) components was calculated from the ratio of the parts by mass of each (B) component to the parts by mass of the (B) component blended in the hydraulic composition, using the following formula: Average circularity of component (B) = Average circularity of B-1 × (parts by mass of B-1 / parts by mass of component (B)) + Average circularity of B-2 × (parts by mass of B-2 / parts by mass of component (B))

[0044] <(C) component> C-1: Alcox L-6 (manufactured by Meisei Chemical Industry Co., Ltd., polyethylene oxide, weight average molecular weight: 60,000) C-2: Alcox R-150 (manufactured by Meisei Chemical Industry Co., Ltd., polyethylene oxide, weight average molecular weight: 150,000) C-3: Alcox R-1000 (manufactured by Meisei Chemical Industry Co., Ltd., polyethylene oxide, weight average molecular weight: 325,000) C-4: Alcox E-30 (manufactured by Meisei Chemical Industry Co., Ltd., polyethylene oxide, weight average molecular weight: 475,000) C-5: Alcox E-45 (manufactured by Meisei Chemical Industry Co., Ltd., polyethylene oxide, weight average molecular weight: 800,000) C-6: Alcox EP1010N (manufactured by Meisei Chemical Industry Co., Ltd., random copolymer of ethylene oxide and propylene oxide, weight average molecular weight: 100,000) <Comparative components of (C') and (C)> C'-1: Polyethylene oxide, molecular weight 1,000,000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) <(D) component> D-1: Tap water (Wakayama City tap water, specific gravity 1.00) <Other ingredients> Accelerator: Aluminum sulfate 14-18 hydrate, Fujifilm Wako Pure Chemical Industries, Ltd.

[0045] (1) Preparation of hydraulic composition Component (A), component (B) or (B'), and component (C) or (C') were charged into a Hobart-type mixer according to JIS R 5201 so as to obtain the blending amounts (parts by mass) shown in Table 1, and dry-mixed for 10 seconds at 62 rpm. Next, component (D) was added so as to obtain the blending amount (parts by mass) shown in Table 1, and kneaded for 2 minutes at 62 rpm to prepare a hydraulic composition, and the fluidity of the hydraulic composition immediately after kneading for 2 minutes was evaluated by the following method.

[0046] (2) Liquidity assessment method For each hydraulic composition immediately after mixing for 2 minutes, the mortar flow (mm) of 15 tapping strokes was measured in accordance with JIS R 5201 and used as an index of fluidity. The results are shown in Table 1.

[0047] (3) Method for assessing changes in liquidity over time Each hydraulic composition whose fluidity was evaluated by the method described in (2) was returned to the Hobart-type mixer described in (1) and further mixed for 2 minutes at 62 rpm, and the mortar flow (mm) was measured by 15 tapping strokes immediately after mixing for a total of 4 minutes by the same method as described in (2). The value calculated by the following formula was used as an index of change in fluidity over time. The results are shown in Table 1. Change in fluidity over time (mm) = 15-tap mortar flow immediately after 2 minutes of mixing (mm) - 15-tap mortar flow immediately after 4 minutes of mixing (mm)

[0048] [Table 1]

[0049] In Table 1, the "amount (parts by mass) relative to (A)" of component (C) or (C') indicates the amount of component (C) or (C') relative to 100 parts by mass of component (A). Furthermore, the "amount (parts by mass) of the quick-setting admixture relative to (A)" indicates the amount of the quick-setting admixture relative to 100 parts by mass of the component (A).

[0050] In Table 1, comparing the Examples and Comparative Examples in which the type and amount of the (B) component are the same (specifically, Examples 1-5 and Comparative Examples 1 and 2, Examples 6-12 and Comparative Example 3, Example 13 and Comparative Example 4, and Example 14 and Comparative Example 5), the Examples of the present invention showed a tendency to suppress the decrease in fluidity even with the extension of the kneading time. This is considered to be because the polyalkylene oxide (C) component of the present invention, which has a moderately large weight-average molecular weight, suppresses the contact and wear between the aggregates, and suppresses the decrease in the workability of the slurry caused by the increase in bound water due to the atomization and the increase in surface area. In this way, the hydraulic composition of the present invention can effectively use fine aggregate with a small circularity (B) and suppresses the decrease in fluidity even with the extension of the kneading or stirring time, so that it is also ideal for the wet spraying method in which the kneading or stirring time is often forced to be extended due to the convenience of the on-site work. In the case of Reference Examples 1 and 2 in which component (B') whose circularity does not satisfy the requirements of the present invention is used instead of component (B), in Reference Example 1 which does not contain component (C), there is no difference in fluidity due to extension of the kneading time, and even in Reference Example 2 in which component (C) is added to Reference Example 1, almost no effect of suppressing fluidity is observed. Therefore, it can be seen that when a fine aggregate other than component (B) is used, the problem of the present invention is not found.

Claims

1. A hydraulic composition containing (A) cement (hereinafter referred to as component (A)), (B) fine aggregate with an average circularity of 0.55 or more and 0.85 or less (hereinafter referred to as component (B)), (C) polyalkylene oxide with a weight-average molecular weight of 5,000 or more and less than 1,000,000 (hereinafter referred to as component (C)), and (D) water (hereinafter referred to as component (D)).

2. The hydraulic composition according to claim 1, wherein the mass ratio (B) / (A) of the content of component (A) to the content of component (B) is 2 or more and 6 or less.

3. The hydraulic composition according to claim 1 or 2, wherein the mass ratio (D) / (A) of the content of component (A) to the content of component (D) is 0.4 or more and 0.8 or less.

4. The hydraulic composition according to claim 1 or 2, wherein the content of component (C) is 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of component (A).

5. (B) The hydraulic composition according to claim 1 or 2, wherein component (B) is crushed sand.

6. The hydraulic composition according to claim 1 or 2, wherein the content of the rapid setting agent is 1 part by weight or less per 100 parts by mass of component (A).

7. A hydraulic composition according to claim 1 or 2, for use in wet spraying.

8. A method for producing a hydraulic composition, comprising mixing (A) cement, (B) fine aggregate having an average circularity of 0.55 or more and 0.85 or less, (C) polyalkylene oxide having a weight-average molecular weight of 5,000 or more and less than 1,000,000, and (D) water.

9. A wet spraying method comprising: (A) cement, (B) fine aggregate with an average circularity of 0.55 or more and 0.85 or less, (C) polyalkylene oxide with a weight-average molecular weight of 5,000 or more and less than 1,000,000, and (D) water to produce a hydraulic composition, and spraying the hydraulic composition onto the target object.