JP2015182900A - Producing method of thin member and thin member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of a thin member and such thin member, the method may provide the thin member having a properties that light, thin, having less curve due to contraction, and having sufficient toughness with cement slurry having a fluidity sufficient for being introduced into corner parts of a frame.SOLUTION: A thin member having a thickness of 1 to 7 mm is produced by hardening the following cement slurry under a state comprising successive two axis arranged fibers. The cement slurry contains: binding material of cement type; water; cement distribution agent; and contraction reducing agent. The cement distribution agent is a poly carboxylic (salt) water soluble vinyl copolymer. The ratio of water binding material is 12 to 25%.

Description

  The present invention relates to a relatively light-weight thin member such as an embedded formwork, an outer wall, an inner wall, a floor board, or a ceiling material in a building / civil engineering field, or a thin member used as a light-weight thin member such as an instrument body or an acoustic member. And a thin member obtained by the manufacturing method.

  Conventionally, in the field of construction and civil engineering, in order to enhance the bending strength and tensile strength of the resulting cured body for the purpose of high strength, high toughness and light weight from the viewpoint of labor saving of concrete construction and wood protection, organic Concrete thin-walled plates containing fibers (for example, see Patent Document 1), thin-walled concrete secondary products containing organic fibers (for example, see Patent Document 2), and the like have been proposed. However, the thickness of these thin plates and thin secondary products is intended for 30 to 50 mm or 15 to 150 mm, and is not suitable for use scenes where a thin member with a thickness of several mm is required. It is. On the other hand, in order to improve the bending strength of cement mortar for the purpose of obtaining a thin molded product having a thickness of 1 to 6 mm, metal fibers (diameter of 0.01 to 0.05 mm, length of 2 to 30 mm) are added to the cementitious slurry. It has also been proposed to knead (short fibers) (see, for example, Patent Documents 3 and 4). However, when the metal fibers are kneaded, the thin molded product obtained becomes heavy, and in fact, in the method of injecting and curing the cement-based slurry in which the metal fibers are kneaded into a narrow formwork of millimeter units, The fluidity of such cement-based slurry is insufficient, and it is difficult to fill the cement-based slurry into every corner of a narrow mold. Further, as the thickness of such a thin molded product becomes thinner, warping due to shrinkage strain occurs. Problems such as cracks become noticeable.

JP 2004-300001 A JP 2004-330752 A JP 2010-137414 A JP 2010-139773 A

  The problem to be solved by the present invention is that the cement-based slurry used has sufficient fluidity that it can be poured into every corner of the thin-walled formwork, and the thin-walled member obtained at the same time is lightweight and thin. Further, the present invention provides a method for manufacturing such a thin-walled member that is less warped due to shrinkage and has sufficient toughness, and a thin-walled member obtained by such a manufacturing method.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have found that a method for producing a thin member by curing a specific cementitious slurry containing a specific organic fiber is correctly suitable. It was.

That is, this invention relates to the manufacturing method of a thin member characterized by manufacturing the thin member of thickness 1-7 mm by hardening the following cementitious slurry in the state containing the continuous biaxially oriented fiber.
Cement-based slurry: Contains cement-based binder, water, cement dispersant and shrinkage reducing agent, the cement dispersant is a polycarboxylic acid (salt) -based water-soluble vinyl copolymer, and has a water binder ratio of 12-25% cement slurry

  In the method for manufacturing a thin-walled member according to the present invention (hereinafter referred to as the manufacturing method of the present invention), as the cement slurry, a cement slurry containing a cement binder, water, a cement dispersant and a shrinkage reducing agent is used. However, as the cement dispersant, a polycarboxylic acid (salt) -based water-soluble vinyl copolymer capable of strongly dispersing cement-based particles in a high concentration cement is used. Even if a cement dispersant such as a known lignin sulfonate, melamine sulfonate formalin high condensate salt, naphthalene sulfonate formalin high condensate salt selected from other compounds is used, it is necessary in the production method of the present invention. Such a sufficient fluidity cannot be obtained. In other words, a cement-based slurry having a low viscosity and a self-filling property with a large flow (spreading) cannot be obtained. The polycarboxylic acid (salt) -based water-soluble vinyl copolymer used in the production method of the present invention is not particularly limited, but it is preferable to use one selected from two groups. One group is methacrylic acid (salt) -based water-soluble vinyl copolymers. This includes, for example, a water-soluble vinyl copolymer obtained from methacrylic acid (salt) and alkoxy polyethylene glycol methacrylate, methacrylic acid (salt), alkoxy polyethylene glycol methacrylate and (meth) allyl sulfonate. Examples thereof include water-soluble vinyl copolymers obtained. These water-soluble vinyl copolymers can be synthesized by a known method. For example, it can be synthesized by the methods described in JP-A-58-74552, JP-A-1-226757 and the like. Another group is a maleic acid (salt) -based water-soluble vinyl copolymer. Examples thereof include a water-soluble vinyl copolymer obtained from maleic acid (salt) and α-allyl ether-ω-methyl-polyoxyethylene, maleic acid (salt) and α-allyl ether-ω-hydroxy-poly. And water-soluble vinyl copolymers obtained from oxyethylene. These water-soluble copolymers can be synthesized by a known method. For example, it can be synthesized by the methods described in JP-A-57-118058, JP-A-2005-132955, JP-A-2008-273766, and the like. In the production method of the present invention, even when any group of polycarboxylic acid (salt) -based water-soluble vinyl copolymers is used, the amount used is 0.2 to 2.0 mass per 100 parts by mass of the binder. It is preferable to make the ratio of parts, more preferably 0.3 to 1.5 parts by mass.

  Among the polycarboxylic acid (salt) water-soluble vinyl copolymers as described above, the flow of the cement-based slurry is large and viscous when kneaded into a cement-based slurry in a region where the water binder ratio is low. Since small ones are judged to have the best packing properties, among the maleic acid (salt) -based water-soluble vinyl copolymers, 45 to 55 mol% of the following structural unit A in the molecule and A maleic acid (salt) -based water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000 having a constitutional unit B of 55 to 45 mol% (total 100 mol%) is preferred. In addition, the mass average molecular weight of the water-soluble vinyl copolymer is a mass average molecular weight in terms of pullulan measured by a GPC method (gel permeation chromatography, the same applies hereinafter).

Structural unit A: One or more selected from a structural unit formed from maleic acid and a structural unit formed from maleate Structural unit B: composed of 10 to 80 oxyethylene units in the molecule [Alpha] -allyl- [omega] -methyl-polyoxyethylene having a polyoxyethylene group and [alpha] -allyl- [omega] having a polyoxyethylene group composed of 10 to 80 oxyethylene units in the molecule One or more selected from structural units formed from hydroxy-polyoxyethylene

  For the same reason, among the above-mentioned methacrylic acid (salt) -based water-soluble vinyl copolymers, 35 to 85 mol% of the following structural unit C and 15 to 65 of the following structural unit D are included in the molecule. A methacrylic acid (salt) -based water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000 having a mol% and the following structural unit E in a proportion of 0 to 5 mol% (100 mol% in total) is preferred.

Structural unit C: One or more selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylic acid salt. Structural unit D: composed of 7 to 90 oxyethylene units in the molecule. A structural unit formed from methoxypolyethylene glycol having a polyoxyethylene group.
Structural unit E: a structural unit composed of (meth) allyl sulfonate.

  In the production method of the present invention, the shrinkage reducing agent is used to suppress self-shrinkage and drying shrinkage of the resulting thin-walled member and prevent warpage and cracking due to shrinkage strain. The use of a shrinkage reducing agent as an essential component of the cement slurry is one of the important requirements and characteristics of the production method of the present invention. The type of shrinkage reducing agent used in the production method of the present invention is not particularly limited, but is preferably selected from polyalkylene glycol monoalkyl ethers having a property of promoting fluidity by a cement dispersant. However, a compound selected from diethylene glycol monobutyl ether and dipropylene glycol diethylene glycol monobutyl ether, which has an excellent shrinkage reduction effect and does not entrain air bubbles when the cement slurry is mixed, is particularly preferable. The amount of the shrinkage reducing agent used is preferably 0.2 to 5.0 parts by mass, and 0.5 to 3.5 parts by mass per 100 parts by mass of the cement-based binder. It is more preferable that This is for better suppressing warpage and shrinkage cracking without causing a decrease in strength of the thin member obtained.

  In the production method of the present invention, the type of cement-based binder used for the cement-based slurry is not particularly limited. Such as Portland cement, blast furnace slag cement, silica fume premix cement, fly ash cement and the like. Especially, since it has the property of keeping the viscosity of the cementitious slurry low even when the cementitious slurry is kneaded in a region where the water cement ratio is low, 5 to 30% (mass ratio) of silica fume fine powder is previously added to Portland cement. It is particularly preferred to use a silica fume premix cement mixed to a proportion.

  In the production method of the present invention, if necessary, in order to further reduce the shrinkage strain of the thin-walled member within a range that does not adversely affect the fluidity of the cementitious slurry, the silica fume fine powder, fly ash fine powder, which is a pozzolanic material, is used. Contains fine powders such as fine powder, slag fine powder, inorganic powders such as quartz powder and calcium carbonate powder, silica sand, crushed sand, natural sand, etc. Can be used.

  In the production method of the present invention, continuous biaxially oriented fibers are used to impart toughness to the resulting thin member. Generally, a cement-based hardened body can be obtained by kneading the cement-based slurry to be hardened in a region where the water binder ratio is low, but a toughness such as bending strength, tensile strength, and elastic modulus is compressive strength. There is a weak point that it is significantly lower than the expression of. In a cement-based thin-walled member that simply has increased compressive strength, brittle fracture occurs when subjected to a strong impact, and therefore it is necessary to use fibers to improve toughness. However, in the method of mixing short fibers in the cement slurry, sufficient toughness required for the thin-walled member is not imparted, and the filling property is remarkably lowered. In order to solve these problems, the production method of the present invention is characterized in that continuous biaxially oriented fibers are used as the fibers. The continuous biaxially oriented fiber is a mesh-like sheet made of organic fibers knitted in a lattice shape. However, in the production method of the present invention, the resulting thin member can be reduced in weight, and at the same time, not only flat but also curved surfaces can be handled. In order to give flexibility, a mesh sheet made of organic fibers is used. Examples of the network sheet made of organic fibers include vinylon fiber sheets, polypropylene fiber sheets, polyethylene fiber sheets, aramid fiber sheets, carbon fiber sheets, etc., from the viewpoint of placing importance on marketability and cost, A polypropylene fiber sheet is preferred. The mesh sheet made of organic fibers preferably has a thickness of 0.1 to 1.5 mm and a mesh size of 0.5 to 10 mm, and the mesh sheet is 3 to 40% by volume% of the thin member. It is preferable to use so that it may become%, and it is more preferable to use so that it may become 5 to 35% especially. These mesh sheets are usually used by being arranged in a direction along the surface of the thin member.

  In the production method of the present invention, first, predetermined amounts of the cement-based binder, water, cement dispersant and shrinkage reducing agent described above are kneaded with a Hobart mixer. The kneading procedure is not particularly limited, but a predetermined amount of cement dispersant and shrinkage reducing agent is preliminarily diluted and dissolved in water, and kneaded while gradually adding the diluted solution to the cement-based binder. A system slurry can be obtained. At this time, it is prepared so that the water binder ratio is in the range of 12 to 25%. If the water binder ratio is smaller than this range, the viscosity of the cementitious slurry will be too high, making it difficult to inject into the mold. Conversely, if it is larger than this range, the strength of the resulting cured product will be reduced and sufficient. A thin member having toughness cannot be obtained. For the same reason, it is preferable to prepare the water binder ratio in the range of 15 to 23%. In kneading, additives such as an antifoaming agent, a setting retarder, a curing accelerator, and a waterproofing agent can be added and used as necessary within the range not impairing the effects of the present invention.

  Next, the cement-based slurry thus prepared is gradually poured into a mold frame in which continuous biaxially oriented fibers are arranged to complete the filling, and is cured for a predetermined time (for example, about 48 hours at room temperature). A thin-walled member can be obtained by removing and securing the pre-treatment time if necessary, and further curing for a predetermined time (for example, 48 hours or more in warm water at 80 to 90 ° C.). The continuous biaxially oriented fibers can be disposed at any position such as a position along the lower surface immediately above the lower surface of the mold or a position along the upper surface directly below the upper surface of the mold, but preferably on both upper and lower surfaces of the mold It arrange | positions in the position in alignment with both upper and lower surfaces in a center part. In addition, when injecting the cement-based slurry into the mold, it is important to use a cement-based slurry having the best possible self-filling property. This is because cement slurry having poor self-fillability cannot be poured into every corner of the mold and filling cannot be completed. Therefore, the flow value of 0 stroke based on the flow test according to JIS-R5201 (cement physical test method) is preferably 300 mm or more, more preferably 350 mm or more, and a B-type rotational viscometer. A viscosity measured at (rotational speed 6 rpm) at 20 ° C. is preferably 5.0 Pa · s or less, more preferably 4.0 Pa · s or less.

  In the production method of the present invention, a thin member having a thickness of 1 to 7 mm, preferably 2 to 6 mm is produced. As such a thin member, a material having a bending strength measured by a plastic material test method (JIS-K7171) of 20 MPa or more, further 25 MPa or more can be obtained as one of the characteristics of the material properties. The form of the thin member obtained can be not only a flat plate but also a curved plate (for example, an S-shaped curved member of a musical instrument, a cylindrical member, etc.).

  The thin member according to the present invention is a thin member obtained by the production method of the present invention described above. Specific forms of the thin-walled member according to the present invention include a light-weight thin-walled member such as an embedded formwork for construction and civil engineering, a building outer wall, an inner wall, and a floorboard, a musical instrument body, and an acoustic member. Etc.

  According to the present invention, using a cement-based slurry having sufficient fluidity that can be poured into every corner of a mold, it is light and thin, has little warpage due to shrinkage, and has sufficient toughness. There is an effect that a thin member can be obtained.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test category 1 (Synthesis of polycarboxylic acid (salt) -based water-soluble vinyl copolymer as cement dispersant)
Synthesis of water-soluble vinyl copolymer (a-1) 98 g (1.0 mol) of maleic anhydride and α-allyl-ω-methyl-poly (33 oxyethylene units, hereinafter n = 33) 1512 g of oxyethylene (1.0 mol) was charged into a reaction vessel, heated gradually and dissolved uniformly with stirring, and then the atmosphere in the reaction vessel was replaced with nitrogen. The temperature of the reaction system was maintained at 83 ° C. in warm water, and 2 g of benzoyl peroxide was added to initiate radical polymerization reaction. Further, 3 g of benzoyl peroxide was added in portions, and the radical polymerization reaction was continued for 4 hours. Next, the obtained copolymer was neutralized by adding 83 g (1.0 mol) of 48% aqueous sodium hydroxide and water to obtain a 40% aqueous solution of the water-soluble vinyl copolymer (a-1). . When this water-soluble vinyl copolymer (a-1) was analyzed, structural units formed from maleic acid / structural units formed from sodium maleate / α-allyl-ω-methyl-poly (n = 33) Polycarboxylic acid (salt) -based water-soluble vinyl copolymer (a- 1).

Synthesis of water-soluble vinyl copolymer (a-2) α-allyl-ω-hydroxy-poly (n = 30) oxyethylene 1370 g (1.0 mol), maleic acid 116 g (1.0 mol) and water 1760 g Was uniformly dissolved with stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 60 ° C. in a warm water bath, and 8 g of a 20% aqueous solution of sodium persulfate was added to initiate radical polymerization reaction. Further, 5 g of a 20% aqueous solution of sodium persulfate was added and the radical polymerization reaction was continued for 5 hours to complete the reaction to obtain a water-soluble vinyl copolymer. Then, 167 g (2.0 mol) of a 48% aqueous sodium hydroxide solution was obtained. Was added to neutralize, and water was added to obtain a 40% aqueous solution of the water-soluble vinyl copolymer (a-2). When this water-soluble vinyl copolymer (a-2) was analyzed, structural unit formed from sodium maleate / structural unit formed from α-allyl-ω-hydroxy-poly (n = 30) oxyethylene = It was a water-soluble vinyl copolymer (a-2) having a mass average molecular weight of 51600 (GPC method, converted to pullulan) at a ratio of 50/50 (mol%).

Synthesis of water-soluble vinyl copolymer (a-3) 60 g of methacrylic acid, 300 g of methoxypoly (n = 23) ethylene glycol methacrylate, 5 g of sodium methallyl sulfonate, 3 g of 3-mercaptopropionic acid and 490 g of water are charged in a reaction vessel. Thereafter, 58 g of a 48% aqueous sodium hydroxide solution was added, and the mixture was partially neutralized with stirring and dissolved uniformly. After the atmosphere in the reaction vessel was replaced with nitrogen, the temperature of the reaction system was maintained at 60 ° C. in a warm water bath, 25 g of a 20% aqueous solution of sodium persulfate was added to start radical polymerization reaction, and the reaction was continued for 5 hours. The reaction was complete. Thereafter, 23 g of a 48% sodium hydroxide aqueous solution was added to completely neutralize the reaction product, thereby obtaining a 40% aqueous solution of the water-soluble vinyl copolymer (a-3). When this water-soluble vinyl copolymer (a-3) was analyzed, a structural unit formed from sodium methacrylate / a structural unit formed from methoxypoly (n = 23) ethylene glycol methacrylate / formed from sodium methallylsulfonate. It was the water-soluble vinyl copolymer (a-3) of the mass mean molecular weight 34200 (GPC method and pullulan conversion) which has the ratio of the comprised structural unit = 70/27/3 (mol%).

Synthesis of water-soluble vinyl copolymer (a-4) Structural unit / methoxypoly (n = 23) ethylene formed from sodium methacrylate by the same method as the synthesis of water-soluble vinyl copolymer (a-3) A water-soluble vinyl copolymer (a-4) having a mass average molecular weight of 49,500 (GPC method, converted to pullulan) having a constitutional unit of 68/32 (mol%) formed from glycol methacrylate was synthesized.

Test category 2 (Preparation of cementitious slurry)
-Preparation of cement-based slurry (S-1) Cement-based slurry was prepared using the materials shown in Table 1 and the formulation shown in Table 2. That is, 1000 parts of a silica fume premix cement as a cement-based binder is put into a Hobart mixer, and then 23 parts of a 40% aqueous solution of a cement dispersant (a-1) synthesized in advance in test section 1 in 186 parts of water and While adding 20 parts of the shrinkage reducing agent (b-1), the mixing speed was gradually increased while rotating the stirring blade at a low speed, and the mixture was kneaded for a total of 8 minutes. A 20% cementitious slurry (S-1) was obtained. As a result of performing a flow test on the cement-based slurry (S-1) in accordance with a physical test method for cement (JIS-R5201), the flow value of 0 stroke measured without performing a drop motion is 390 mm, and B-type rotation The viscosity (measuring condition: rotor No. 2, rotational speed 6 rpm) measured with a viscometer was 1.75 Pa · s at 20 ° C.

In Table 2,
a-1 to a-4: Water-soluble vinyl copolymers listed in Table 1 (mass is in terms of solid)
b-1, b-2: Shrinkage reducing agents described in Table 1 Fine aggregate: Silica sand described in Table 1 * 1: Sodium lignin sulfonate * 2: Melamine sulfonate formalin high condensate salt * 3: Naphthalene sulfonic acid Formalin high condensate salt

Preparation of cement-based slurry (S-2) to (S-8) and (SR-1) to (SR-6) In the same manner as the preparation of cement-based slurry (S-1), cement-based slurry (S- 2) to (S-8) and (SR-1) to (SR-6) were prepared. The contents of each cementitious slurry prepared above are shown in Table 3.

In Table 3,
M-1 to M-14: Formulation number described in Table 2 Flow value: Flow test of 0 stroke according to the physical test method of cement (JIS-R5201) immediately after kneading and after 60 minutes. Flow value when done.
Viscosity: Viscosity at 20 ° C. measured using a B-type rotational viscometer immediately after kneading * 4: The target fluidity was not obtained even when the amount of cement dispersant added was increased.
* 5: Similarly, fluidity was not obtained.

Test Category 3 (Manufacture of thin parts)
Example 1
In the test section 2 in a thin rectangular parallelepiped mold having a thickness of 3 mm and a length of 100 mm and a width of 1000 mm in which the continuous biaxially oriented fibers described in Table 1 are arranged at positions along the upper and lower surfaces at the center of the upper and lower surfaces of the mold. The prepared cementitious slurry (S-1) was gradually poured from above. After the filling was completed, the mold was removed by leaving it in the room for 48 hours, and then left standing at 20 ° C. for 24 hours, followed by pre-curing. Next, the pre-cured material was immersed in warm water at 85 ° C. for 7 days and cured with warm water to obtain a thin plate member (H-1) having a thickness of 3 mm. Similarly, filling of the thin plate member having a curved plate shape with an S-shaped cross section could be completed without any trouble, and a thin member could be obtained.

Examples 2 to 10 and Comparative Examples 1 to 7
In the same manner as Example 1, thin-walled members H-2 to H-10 and RH-1 to RH-7 of Examples 2 to 10 and Comparative Examples 1 to 7 were obtained. Table 4 summarizes the contents of the thin-walled members manufactured in each of the above examples.

Test category 4 (Evaluation of thin parts)
About the thin member of each manufactured example, the curvature by bending strength and shrinkage distortion was calculated | required as follows, and the result was put together in Table 4 and shown.
-Bending strength (MPa): Based on JIS-K7171 of the testing method of a plastic material, it measured at the age of 7 days after 85 degreeC warm water curing about the flat thin member of each example.
-Curing of hardened body due to shrinkage strain (mm): The flat thin member of each example was removed from the formwork, and then allowed to stand in a room conditioned at 20 ° C and RH 60% for 28 days. Next, one end in the horizontal direction was fixed horizontally, and the warp width from the horizontal plane of the other end was measured. It shows that the smaller the numerical value of the warp width, the less warp due to shrinkage strain and the better the dimensional stability.

In Table 4,
Content ratio (%) of continuous biaxially oriented fiber in thin-walled material: Volume (%)
Bending strength: Value measured in accordance with JIS-K7171 Bending strength enhancement rate: Ratio of comparative example 7 (when continuous biaxially oriented fibers are not used) to thin member * 6: Thin member was not obtained So did not measure

  As is apparent from the results of Tables 3 and 4, according to the production method of the present invention, the cement-type slurry having sufficient fluidity that can be poured into every corner of the mold is used to reduce the weight and thickness. There is an effect that it is possible to obtain a thin-walled member that is thin, has little warpage due to shrinkage, and has sufficient toughness.

Claims (12)

A method for producing a thin-walled member, comprising producing a thin-walled member having a thickness of 1 to 7 mm by curing the following cementitious slurry in a state including continuous biaxially oriented fibers.
Cement-based slurry: Contains cement-based binder, water, cement dispersant and shrinkage reducing agent, the cement dispersant is a polycarboxylic acid (salt) -based water-soluble vinyl copolymer, and has a water binder ratio of 12-25% cement slurry   The cement-based slurry contains 0.2 to 2.0 parts by mass of a polycarboxylic acid (salt) -based water-soluble vinyl copolymer per 100 parts by mass of the cement-based binder. Manufacturing method of thin member. The polycarboxylic acid (salt) -based water-soluble vinyl copolymer contains 45 to 55 mol% of the following structural unit A and 55 to 45 mol% (100 mol% in total) of the following structural unit B in the molecule. The method for producing a thin member according to claim 1 or 2, which is a water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000.
Structural unit A: One or more selected from a structural unit formed from maleic acid and a structural unit formed from maleate Structural unit B: composed of 10 to 80 oxyethylene units in the molecule [Alpha] -allyl- [omega] -methyl-polyoxyethylene having a polyoxyethylene group and [alpha] -allyl- [omega] having a polyoxyethylene group composed of 10 to 80 oxyethylene units in the molecule One or more selected from structural units formed from hydroxy-polyoxyethylene The polycarboxylic acid (salt) -based water-soluble vinyl copolymer contains 35 to 85 mol% of the following structural unit C, 15 to 65 mol% of the following structural unit D, and 0 to 0 of the following structural unit E in the molecule. The method for producing a thin-walled member according to claim 1 or 2, which is a water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000 having a ratio of 5 mol% (total of 100 mol%).
Structural unit C: One or more selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylic acid salt. Structural unit D: composed of 7 to 90 oxyethylene units in the molecule. A structural unit formed from methoxypolyethylene glycol having a polyoxyethylene group.
Structural unit E: a structural unit composed of (meth) allyl sulfonate.   The shrinkage reducing agent is selected from diethylene glycol monobutyl ether and dipropylene glycol diethylene glycol monobutyl ether, and the cement slurry is 0.5 to 3.5 parts by weight of the shrinkage reducing agent per 100 parts by weight of the cement-based binder. The method for producing a thin-walled member according to any one of claims 1 to 4, wherein the thin-walled member is contained in a proportion.   The method for producing a thin member according to any one of claims 1 to 5, wherein the cement-based binder is silica fume premix cement.   A network sheet composed of organic fibers in which continuous biaxially oriented fibers are knitted in a lattice shape, the mesh sheet having a thickness of 0.1 to 1.5 mm and a mesh size of 0.5 to 10 mm, The method for producing a thin member according to any one of claims 1 to 6, wherein the mesh sheet is used so that the volume percent of the thin member is 3 to 40%.   The method for producing a thin member according to claim 7, wherein the mesh sheet is a mesh vinylon fiber sheet.   The method for producing a thin member according to any one of claims 1 to 8, wherein the thin member is a flat plate or a curved plate having a thickness of 2 to 6 mm.   The cement-based slurry has a zero flow value measured in accordance with a cement physical test method (JIS-R5201) of 300 mm or more and a viscosity of 5.0 Pa · s or less. The method for producing a thin member according to any one of 1 to 9.   The thin member obtained by the manufacturing method of the thin member as described in any one of Claims 1-10.   The thin-walled member according to claim 11, wherein the thin-walled member has a bending strength of 20 MPa or more measured in accordance with a plastic material test method (JIS-K7171).