JP2010137414A - Method for manufacturing cement-based sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a cement-based sheet, capable of being formed to be ultrathin and excellent in high class feeling, stateliness, and shininess. <P>SOLUTION: The method for manufacturing the cement-based sheet includes: the kneading step of obtaining a compound 2 by kneading (A) cement, (B) fine powders having BET specific surface area of 5-25 m<SP>2</SP>/g, (C) a fine aggregate, (D) a water reducing agent, (E) metal fiber, and (F) water; a molding step which casts the compound 2 obtained in the kneading step in a formwork 1 where a material for forming at least a bottom surface is glass or synthetic resin, and performs a molding of the compound 2 by closely attaching the compound 2 cast in the formwork 1 with a face-down formwork 3 having nonwoven fabric 3a so that the nonwoven fabric 3a opposes to the compound 2; the curing step which cures the compound 2 in such a state that the compound 2 in the formwork 1 and the face-down formwork 3 are closely attached, and obtains a hardened body of the compound 2; and the demolding step which obtains the cement-based sheet 4 having a shiny surface 4a by demolding the hardened body of the compound 2 from the formwork 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a cement-based thin plate, and more particularly to a method for manufacturing a cement-based thin plate having a mirror-like single side with excellent glossiness and having a high-class feeling, a heavy feeling, and an excellent design.

Cement-based hardened bodies such as mortar are generally composed of cement, aggregate, water, water reducing agent, etc., and can be molded into any shape, and have advantages such as excellent mechanical strength and durability. For this reason, they are widely used as members (wall materials, floor materials, ceiling materials, etc.) for general houses and buildings, for example.
However, unlike cement and other high-grade materials, cement-based hardened bodies generally lack a sense of luxury, profoundness, and gloss, so, for example, a sense of quality such as a wall material or flooring in a hotel or hotel lobby, It is difficult to apply as it is without applying a surface treatment or the like to an application that requires a profound feeling and glossiness.
Moreover, the compressive strength of the cement-type hardened body used for a general house, a building, etc. is 20-30 N / mm < ² > normally. Therefore, it is necessary to increase the thickness of concrete members (for example, wall materials, floor materials, ceiling materials, etc.) such as ordinary houses and buildings. In particular, in the case of precast products, there are problems such as difficult transportation work. is there.
In order to solve these problems, 100 parts by weight of cement, 5 to 50 parts by weight of pozzolanic fine powder, 50 to 250 parts by weight of fine aggregate having a particle size of 2 mm or less, and a water reducing agent in a solid content equivalent of 0.5 to A cured product obtained by pouring a compound containing 4.0 parts by weight and 10 to 30 parts by weight of water into a resin mold, and having a surface roughness (Rmax) of 10 μm or less without surface polishing. There has been proposed a cured product characterized in that (Patent Document 1).
Japanese Patent No. 4167379

According to the technique described in Patent Document 1, it is possible to obtain a cement-based cured body having a high-class feeling, a heavy feeling, and glossiness without performing surface treatment. However, Patent Document 1 does not describe, for example, manufacturing an ultrathin plate having a thickness of 6 mm or less.
Therefore, an object of the present invention is to provide a method for producing a cement-based thin plate that can be formed into an ultra-thin wall of, for example, 6 mm or less, and is excellent in high-grade feeling, heavy feeling, and glossiness.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a specific cement-based compound, a mold having a glass or synthetic resin as a material forming at least the bottom, and a water-permeable or air-permeable member. The present invention was completed by finding that the above object of the present invention can be achieved by sandwiching and forming with a cover form.

That is, the present invention provides the following [1] to [3].
[1] (A) cement, (B) fine powder having a BET specific surface area of 5 to 25 m ² / g, (C) fine aggregate, (D) water reducing agent, (E) metal fiber, and (F) water, A kneading step for kneading the mixture, and the mixture obtained in the kneading step is put into a mold whose material forming at least the bottom surface is glass or synthetic resin, and then put into the mold The molded product is formed by adhering the blended composition and the facing mold including the water-permeable or air-permeable member so that the water-permeable or air-permeable member faces the compound. A molding step to be performed, a curing step in which the compound in the mold and the cover mold are kept in close contact with each other and the compound is cured to obtain a cured product of the compound, and curing of the compound By removing the body from the formwork, a cement-based thin plate made of a cured body of the compound is obtained. Method for manufacturing a cementitious sheet which comprises a demolding step.
[2] The method for producing a cement-based thin plate according to [1], wherein the blend in the kneading step includes (G) an inorganic powder having a brain specific surface area of 4,000 to 10,000 cm ² / g.
[3] The method for producing a cement-based thin plate according to [1] or [2], wherein the cement-based thin plate has a thickness of 1 to 6 mm.

According to the present invention, since a specific formulation and two specific types of molds are used, large bubbles are not mixed in the cured product of the formulation, and the entire cured product of the formulation is uniform and A large mechanical strength (for example, compressive strength, bending strength, etc.) can be ensured. Therefore, even when an ultra-thin cement-based sheet having a thickness of 6 mm or less is manufactured, the cement-based sheet does not cause cracks or defects caused by bubbles, and the cement-based sheet can be used as a building such as a general house or a building. Can be used as a thin-walled member on the surface portion of various members.
Further, according to the present invention, since a specific composition and two specific types of molds are used, it is possible to give an excellent gloss of a mirror surface to one side of a cement-based thin plate. Such a cementitious thin plate has a high-class feeling, a heavy feeling, and an excellent design. For this reason, for example, it can be applied as it is without surface treatment to applications that require a high-class feeling, profound feeling, and glossiness such as wall materials and flooring materials in inns and hotel lobbies. Can do.
Furthermore, according to the present invention, since a specific composition is used, it is possible to form a cement-based thin plate having excellent workability before curing and having high dimensional accuracy even if it is ultra-thin.

The method for producing a cement-based sheet according to the present invention comprises (a) (A) cement, (B) fine powder having a BET specific surface area of 5 to 25 m ² / g, (C) fine aggregate, (D) water reducing agent, ( E) A kneading step in which a metal fiber and (F) water are kneaded to obtain a blend, and (b) a mold in which the material forming at least the bottom surface of the blend obtained in the kneading step is glass or a synthetic resin. Then, the mixture is put into the frame, and then the blended composition is put into the formwork and the laying mold including the water-permeable or gas-permeable member is opposed to the water-permeable or gas-permeable member. In this way, the molding step for molding the formulation, and (c) curing the formulation in a state where the formulation in the mold and the cover mold remain in contact with each other, A curing step for obtaining a cured body of the blend; and (d) removing the cured body of the blend from the mold. By, it is intended to include a demolding step to obtain a cementitious thin plate made of a cured product of the formulation.
Hereinafter, it demonstrates for every process.

[(A) Kneading step]
Step (a) is a step of kneading the components (A) to (F) and other optional components blended as necessary to obtain a cement-based blend.
First, each component which comprises a compound is demonstrated.
As the (A) cement, various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, and low heat Portland cement can be used.
In the present invention, it is preferable to use moderately hot Portland cement or low heat Portland cement from the viewpoints of fluidity and strength development of the blend, reduction of curing shrinkage, and the like.

The fine powder (B) has a BET specific surface area of 5 to 25 m ² / g, preferably 7 to 15 m ² / g. When the BET specific surface area is less than 5 m ² / g, the mechanical strength after curing decreases, and it becomes difficult to produce a thin plate having a thickness of 6 mm or less. On the other hand, when the BET specific surface area exceeds 25 m ² / g, the amount of water for obtaining a predetermined fluidity increases, the mechanical strength after curing decreases, and a thin plate having a thickness of 6 mm or less can be produced. It becomes difficult.
(B) Examples of the fine powder include silica fume, silica dust, fly ash, slag, volcanic ash, silica sol, precipitated silica, and limestone powder. In general, silica fume and silica dust have a BET specific surface area of 5 to 25 m ² / g and are not necessary to be pulverized, and thus are suitable as the fine powder of the present invention. Further, limestone powder is also preferably used from the viewpoint of pulverizability and fluidity.
(B) As for the compounding quantity of fine powder, 10-40 mass parts is preferable with respect to 100 mass parts of (A) cement, and 15-35 mass parts is more preferable. When the blending amount is less than 10 parts by mass, the mechanical strength after curing is lowered, and it becomes difficult to produce a thin plate having an ultrathin thickness (for example, a thickness of 6 mm or less). When the blending amount exceeds 40 parts by mass, the amount of water for obtaining a predetermined fluidity increases, the mechanical strength after curing decreases, and a thin plate having a very thin thickness (for example, 6 mm or less) is obtained. It becomes difficult to manufacture.

(C) As fine aggregate, river sand, land sand, sea sand, crushed sand, silica sand, or a mixture thereof can be used.
In the present invention, from the viewpoint of obtaining a fluidity and workability of the composition, crack resistance after curing, and a thin plate of ultrathin thickness (for example, a thickness of 6 mm or less), the maximum particle size of the fine aggregate is The thickness is preferably ¼ or less of the thickness of the thin plate to be manufactured, more preferably ５ or less of the thickness, and particularly preferably ６ or less of the thickness.
Further, from the viewpoint of fluidity and workability of the blend, the proportion of particles having a particle size of less than 0.15 mm in the fine aggregate is preferably 5% by mass or more.
(C) As for the compounding quantity of a fine aggregate, 50-150 mass parts is preferable with respect to 100 mass parts of (A) cement, and 70-140 mass parts is more preferable. If the blending amount is outside the above numerical range, the mechanical strength after curing is decreased, and it becomes difficult to produce a thin plate having a very thin thickness (for example, 6 mm or less in thickness), or the curing shrinkage rate. Becomes larger.

(D) As a water reducing agent, a lignin type, naphthalenesulfonic acid type, melamine type, polycarboxylic acid type water reducing agent, AE water reducing agent, high performance water reducing agent or high performance AE water reducing agent can be used. Among them, it is preferable to use a polycarboxylic acid-based high-performance water reducing agent or a high-performance AE water reducing agent because a greater water reduction effect can be obtained. (D) By mix | blending a water reducing agent, the fluidity | liquidity and workability of a compound, the denseness after hardening, mechanical strength, etc. can be improved.
(D) As for the compounding quantity of a water reducing agent, 0.1-4.0 mass parts is preferable in conversion of solid content with respect to 100 mass parts of (A) cement, and 0.1-1.0 mass part is more preferable. When the blending amount is out of the above numerical range, the fluidity of the blend, the mechanical strength after curing, the static elastic modulus and the like are lowered.

(E) As a metal fiber, a steel fiber, an amorphous fiber, etc. are mentioned. Among these, steel fibers are excellent in strength, and are preferably used from the viewpoint of cost and availability. The metal fibers preferably have a diameter of 0.01 to 0.5 mm and a length of 2 to 30 mm. If the diameter is less than 0.01 mm, the strength of the fiber itself is insufficient, and it is easy to break when subjected to tension. When the diameter exceeds 0.5 mm, the number of the same compounding amount decreases, the effect of improving the bending strength and fracture energy is reduced, and an ultrathin sheet (for example, a thickness of 6 mm or less) can be manufactured. It becomes difficult. If the length exceeds 30 mm, fiber balls are likely to be produced during kneading. On the other hand, if the length is less than 2 mm, the effect of improving bending strength and fracture energy is reduced, and a thin plate with an ultrathin thickness (for example, a thickness of 6 mm or less). It becomes difficult to manufacture.
(E) As for the compounding quantity of a metal fiber, 0.5-4% of the volume of a compound is preferable, More preferably, it is 1-3%. When the blending amount exceeds 4%, the unit water amount increases in order to ensure workability during kneading, the bending strength after curing decreases, and the like is a thin plate with a very thin thickness (for example, a thickness of 6 mm or less). It becomes difficult to manufacture. On the other hand, even if the blending amount is less than 0.5%, the bending strength after curing is decreased, and it becomes difficult to produce a thin plate having an ultrathin thickness (for example, a thickness of 6 mm or less).

(F) As water, tap water etc. can be used.
(F) Water is blended in such an amount that the water / cement ratio is preferably 10 to 30% by mass, more preferably 13 to 25% by mass. If the water / cement ratio is less than 10% by mass, the fluidity of the compound is lowered, and operations such as molding become difficult. On the other hand, if the water / cement ratio exceeds 30% by mass, the mechanical strength after curing decreases, and it becomes difficult to produce a thin plate having an ultrathin thickness (for example, a thickness of 6 mm or less).

The blend of step (a) can further contain (G) inorganic powder from the viewpoint of improving fluidity, mechanical strength after curing, durability, and the like.
(G) an inorganic powder preferably has a Blaine specific surface area of 4,000~10,000cm ² / g, more preferably 5,000~9,000cm ² / g. If the Blaine specific surface area is less than 4,000 cm ² / g, the effect of improving the fluidity is lowered, and the effect of improving the mechanical strength, static elastic modulus, denseness, impact resistance and the like after curing is also reduced. Is not preferable. On the other hand, if the Blaine specific surface area exceeds 10,000 cm ² / g, the fluidity may be lowered, and the mechanical strength after curing and the static elastic modulus may be lowered. Furthermore, this case is not preferable because the cost increases.

(G) Examples of the inorganic powder include inorganic powders other than cement, such as slag, limestone powder, feldspar, mullite, alumina powder, quartz powder, fly ash, volcanic ash, silica sol, carbide powder, and nitride powder. . Among them, slag, fly ash, limestone powder, and quartz powder are preferably used in terms of cost and quality stability after curing.
(G) The compounding quantity of inorganic powder becomes like this. Preferably it is 50 mass parts or less with respect to 100 mass parts of cement, More preferably, it is 40 mass parts or less. When the amount exceeds 50 parts by mass, fluidity, workability, mechanical strength after curing, denseness, impact resistance, and the like may decrease.
Moreover, the compounding quantity of (G) inorganic powder becomes like this. Preferably it is 5 mass parts or more with respect to 100 mass parts of cement, More preferably, it is 7 mass parts or more. By setting the blending amount to 5 parts by mass or more, it is possible to enhance the improvement effects such as the fluidity of the blend, the mechanical strength after curing, and the durability.

In addition, the blend of step (a) comprises (H) fibrous particles or flaky particles having an average particle size of 1 mm or less from the viewpoint of improving toughness after curing and (E) preventing separation of metal fibers. Can be included. Here, the particle size of the particle is the size of the maximum dimension (particularly, the length of the fibrous particle).
Examples of fibrous particles include wollastonite, bauxite, and mullite. Examples of the flaky particles include mica flakes, talc flakes, vermiculite flakes, and alumina flakes.
The blending amount of fibrous particles or flaky particles (however, when these two types of particles are used in combination) is (A) 100 mass of cement from the viewpoint of workability before curing, toughness after curing, and the like. 35 parts by mass or less is preferable with respect to parts, and 0.1 to 5 parts by mass is more preferable.
In addition, it is preferable to use a fibrous particle having a needle-like degree represented by a length / diameter ratio of 3 or more from the viewpoint of increasing toughness after curing.

In the step (a), a blend is obtained by kneading the above materials.
Although it does not specifically limit as a concrete kneading method, For example, the method of following (1)-(3) is mentioned.
(1) A method in which materials other than water and a water reducing agent are mixed in advance to prepare a premix material, and then the premix material, water and water reducing agent are put into a mixer and kneaded. (2) Materials other than water ( However, the water reducing agent is a powder type.) A premix material is prepared in advance and a premix material is prepared, and then the premix material and water are put into a mixer and kneaded (3) Method of mixing and kneading each separately The mixer used for kneading may be any type used for ordinary concrete kneading, such as an omni mixer, a pan-type mixer, a biaxial kneading mixer, a tilting cylinder mixer, etc. Conventional mixers can be used.

[(B) Molding step]
A process (b) is a process of shape | molding the compound obtained by the process (a) using a specific formwork and a specific hiding formwork.
The mold used in the step (b) only needs to have at least a bottom surface made of glass or synthetic resin.
By using a mold with at least the bottom surface made of glass or synthetic resin, a hardened body (cement-based thin plate) having excellent gloss with one side that is in contact with the bottom surface of the mold is mirror-like. can do.
Examples of the synthetic resin for forming the bottom surface include polyvinyl chloride, polyethylene, polypropylene, and polycarbonate.
In the present invention, it is preferable to use glass as a material for forming the bottom surface of the mold because it can impart more excellent gloss and the like to the surface in contact with the bottom of the mold.
Usually, a mold is fixed to a member for forming a side wall having a predetermined height (for example, 1 to 6 mm) with an adhesive or the like around the bottom of the member for forming the bottom of the mold. It will be.
The material of the member for forming the side wall is not particularly limited, and examples thereof include metals such as wood, synthetic resin, and steel.

The hiding formwork used in the step (b) is a hiding formwork including a water-permeable or air-permeable member and is usually a surface of a member (for example, a steel plate, a synthetic resin plate, etc.) that does not have water-permeability and air-permeability. Among them, a sheet formed by attaching a sheet-like water-permeable or air-permeable member to at least a portion to be in close contact with the cementitious compound is used.
In addition, in this specification, a turndown formwork means the formwork used in combination with the formwork which can accommodate a cement-type compound. The cement-based thin plate of the present invention has a glossy surface formed by a glass or synthetic resin bottom surface of a mold that can contain a cement-based compound, and the back surface thereof, It is formed by a turndown mold and does not have gloss.
Examples of the water permeable or air permeable member include a nonwoven fabric and a woven fabric.
By using a cover-up form that includes a water-permeable or air-permeable member, it is possible to prevent large bubbles from being generated on the surface of the cement-based sheet that contacts the cover-up form, and the mechanical strength of the entire cement-based sheet. Can be ensured and the occurrence of cracks and breakage in the cement-based thin plate can be prevented.

[(C) Curing process]
Step (c) is a step of curing the blend and obtaining a cured product of the blend in a state where the blend in the mold and the lying mold are in close contact with each other.
The curing method is not particularly limited, but considering the productivity and strength development of the cement-based thin plate, for example, the following primary curing method and secondary curing method are preferable.
(Primary curing)
First, the composition in the mold is left to stand at a temperature of 5 to 40 ° C. for a predetermined time (for example, 3 to 48 hours) while being held down by the facing mold.
(Secondary curing)
After completion of primary curing, steam curing is performed at 75 to 95 ° C. for 10 to 48 hours while the cured formulation is held down with the face down formwork.

[(D) Demolding step]
Step (d) is a step of removing the cured product of the blend obtained in step (c) from the mold and obtaining a cement-based thin plate.
The thickness of the cement-based thin plate is preferably 6 mm or less, and more preferably 5 mm or less, from the viewpoint of preventing generation of large bubbles and lightness.
Moreover, it is preferable that the thickness of a cement-type thin plate is 1 mm or more from a viewpoint of ensuring the mechanical strength of the whole cement-type thin plate.
Cement-based thin plate is used for pasting, pillars, walls, floors, etc. of various newly built or existing buildings such as hotels and apartments, etc., so that it has high quality, solidness, and high design. A space can be created.

The preferred physical properties of the compound constituting the cement-based sheet before and after curing are as follows.
The flow value of the compound before curing is preferably 150 mm as a value measured without performing 15 drop motions in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”. Above, more preferably 180 mm or more, particularly preferably 210 mm or more.
Compressive strength of the cured product of the formulation, is preferably 180 N / mm ² or more, more preferably 190 N / mm ² or more, particularly preferably 200 N / mm ² or more. When the compressive strength is less than 180 N / mm ² , the mechanical strength of the entire cured body may be insufficient. In this specification, the compressive strength is a value measured according to “JIS A 1108 (Concrete compressive strength test method)”.
Flexural strength of the cured product of the formulation is preferably 35N / mm ² or more, more preferably 37N / mm ² or more, and particularly preferably 40N / mm ² or more. It is preferable that the bending strength is 35 N / mm ² or more because the mechanical strength of the entire cured body is increased. In this specification, the bending strength is a value measured according to “JIS R 5201 (physical test method for cement)”.

Density of the cured product of the formulation is preferably 2.50~2.60g / cm ^3, more preferably 2.52~2.58g / cm ^3. When the density is less than 2.50 g / cm ^3, it is difficult to obtain a compressive strength of 180 N / mm ² or more, and as a result, the mechanical strength of the entire cured body may be insufficient. When the density exceeds 2.60 g / cm ³ , the mass of the entire cured body increases, which is not preferable in terms of increasing the work load during transportation and attachment of the cement-based thin plate.
The elastic modulus of the cured product of the blend is preferably 50 kN / mm ² or more, and more preferably 52 to 65 kN / mm ² . When the elastic modulus is less than 50 kN / mm ^2, it is difficult to obtain a compressive strength of 180 N / mm ² or more, and as a result, the mechanical strength of the entire cured body may be insufficient. In this specification, the elastic modulus is a value measured according to “JIS A 1149 (static elastic modulus test method for concrete)”.

Next, an example of the manufacturing method of the cement-type thin plate of this invention is demonstrated, referring drawings. FIG. 1 is a diagram showing an example of a method for producing a cement-based thin plate of the present invention.
In FIG. 1, until the upper end of the formwork 1 is reached in the formwork 1 composed of the glass member 1a having a smooth upper surface and the wooden side wall 1b, the cement-based composition 2 obtained in the step (a). (Fig. 1 (A)). Next, molding of the blend 2 is performed by bringing the entire top surface of the blend 2 in the mold 1 into close contact with the entire surface of the nonwoven fabric 3a of the cover mold 3 ((B) in FIG. 1). In addition, the turndown mold 3 is formed by sticking a nonwoven fabric 3a which is a water-permeable or air-permeable member to the steel plate 3b.
The mixture 2 may be charged up to the upper end of the side wall 1b of the mold 1 or may be charged so as to be lower than the upper end (for example, to the middle of the depth of the mold 1). Also good.
In the case where the compound 2 is charged up to the upper end of the side wall 1b of the mold 1, a face-down mold having substantially the same area as the top surface of the compound 2 in the mold 1 is used as the compound 2 in the mold 1. The upper surface may be brought into close contact with the upper surface, or, as shown in (b) of FIG. 1, an underlay mold 3 having a larger area than the upper surface of the composition 2 in the mold 1 may be used. In this case, the non-woven fabric 3a of the cover mold 3 and the compound 2 can be brought into close contact with each other by placing the cover mold 3 on the upper surface of the side wall 1b of the mold 1.
When the compound 2 is introduced to a height below the upper end of the side wall 1b, an overlaid mold (not shown) having the same area as the upper surface of the compound 2 in the mold 1 is used as the mold 1. It is necessary to fit the inside of the nonwoven fabric 3a of the face-down mold 3 to the upper surface of the compound 2 in the mold 1 by fitting it inside.

After molding of the blend, curing of the blend 2 in the mold 1 is performed in a state where the blend 2 in the mold 1 and the face-down mold 3 are kept in close contact ((b) in FIG. 1).
After curing, after removing the lying mold 3, the hardened body of the composition 2 is removed from the mold 1 to obtain a cement-based thin plate 4 made of the hardened body of the composition 2 ((C in FIG. 1). )).
The cement-based thin plate 4 has a surface (front surface) 4a that has been in contact with the bottom surface of the mold 1 and a surface (back surface) 4b that is on the opposite side and that has been in contact with the nonwoven fabric 3a of the face-down mold 3. . The surface 4a is a smooth surface having a specular gloss, and imparts a high-class feeling, a heavy feeling, and a glossiness to the cement-based thin plate 4.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Preparation of materials]
The following materials were prepared as constituent materials for the cement-based thin plate.
(A) Cement: Low heat Portland cement (manufactured by Taiheiyo Cement)
(B) Fine powder; silica fume (BET specific surface area 10 m ² / g)
(C) Fine aggregate; quartz sand (particle size 0.15 to 0.6 mm)
(D) Water reducing agent; polycarboxylic acid-based high-performance water reducing agent (E) metal fiber; steel fiber (diameter: 0.15 mm, length: 15 mm)
(F) Water; Tap water (G) Inorganic powder; Quartz powder (Blaine specific surface area 7,500 cm ² / g)

[Example 1; Measurement of various physical properties]
100 parts by mass of cement, 30 parts by mass of silica fume, 105 parts by mass of fine aggregate, 0.5 parts by mass of water reducing agent (solid content with respect to cement), steel fibers (2% of the volume of the compound), 22 parts by mass of water, quartz powder 30 parts by mass was charged into a biaxial kneader and kneaded to obtain a blend.
In the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”, the flow value of the obtained blend was measured without performing 15 drop motions. As a result, the flow value was 270 mm.
In addition, the mixture was poured into a mold of φ50 × 100 mm, allowed to stand at 20 ° C. for 48 hours (primary curing), demolded, and further subjected to steam curing (secondary curing) at 90 ° C. for 48 hours to obtain a cured body. It was. The compression strength and static elastic modulus of the obtained cured product were measured in accordance with “JIS A 1108 (Concrete compressive strength test method)” and “JIS A 1149 (Concrete static elastic modulus test method)”, respectively. As a result, the compressive strength was 230 N / mm ² and the static elastic modulus was 55 kN / mm ² .
In addition, the composition was poured into a 4 × 4 × 16 cm mold, left at 20 ° C. for 48 hours (primary curing), demolded, and further steam-cured (secondary curing) at 90 ° C. for 48 hours to cure. Got the body. The bending strength of the obtained cured product was measured according to “JIS R 5201”. As a result, the bending strength was 45 N / mm ² .
The density of the cured product of the blend was 2.55 g / cm ³ .

[Example 2; Production of cement-based sheet]
On the upper surface of the glass plate, a side wall made of a decorative plywood was attached with a double-sided tape to prepare a form having an internal space of 20 cm × 20 cm × 3 mm (depth) opened only at the top. Moreover, the nonwoven fabric was affixed on the single side | surface of the steel plate, and the down formwork was produced.
After pouring the compound obtained in Example 1 into the mold so as to have a thickness of 3 mm up to the upper end, the compound in the mold and the cover mold are placed on the nonwoven fabric side of the cover mold. It was made to adhere so that the upper surface of a blend might be countered. Next, after standing for 24 hours at 20 ° C. (primary curing), steam curing (secondary curing) is performed at 90 ° C. for 48 hours, and then demolded to obtain a cement-based thin plate of 20 cm × 20 cm × 3 mm. Obtained.
The same manufacturing procedure was repeated and 10 cement-based thin plates were manufactured. As a result, no cracks or chipped portions were generated, and it was possible to manufacture without problems. In addition, when the surface of the cement-based thin plate (the surface that was in contact with the bottom surface of the formwork) was visually observed, it had a high-class feeling, a heavy feeling, and a specular gloss, and was excellent in design. .

[Comparative Example 1]
A cement-based thin plate was obtained in the same manner as in Example 1 except that a concealed form was made of only a steel plate and did not contain a water-permeable or air-permeable member.
The same manufacturing procedure was repeated to produce 10 cement-based thin plates. Among them, several large bubbles were observed on the back surface (the surface that was in contact with the face-down formwork), and cracks were observed from the bubbles. A defect occurred.
[Comparative Example 2]
As a blend, 100 parts by mass of cement, 30 parts by mass of silica fume, 105 parts by mass of fine aggregate, 0.5 parts by mass of water reducing agent (solid content with respect to cement), 22 parts by mass of water, and 30 parts by mass of quartz powder were mixed in a biaxial mixer. A cementitious thin plate was obtained in the same manner as in Example 1 except that the compound obtained by mixing and kneading was used.
The same manufacturing procedure was repeated to produce 10 cement-based thin plates, and in 4 of them, cracks and defects occurred during demolding.

  As described above, according to the method for producing a cement-based thin plate of the present invention, since the hardened body of the cement-based compound does not contain bubbles, an ultra-thin wall (for example, 1 It can be seen that a cement-based thin plate having a high-quality feeling, a heavy feeling, and glossiness can be obtained.

It is a figure which shows an example of the manufacturing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Formwork 1a Glass member 1b Side wall 2 Compound 3 Face-down formwork 3a Nonwoven fabric (water-permeable or air-permeable member)
3b Steel plate 4 Cement-based thin plate 4a Surface (surface with excellent gloss)
4b Back side

Claims (3)

(A) Cement, (B) Fine powder having a BET specific surface area of 5 to 25 m ² / g, (C) Fine aggregate, (D) Water reducing agent, (E) Metal fiber, and (F) Water are kneaded. Kneading step to obtain a blended product,
The compound obtained in the kneading step is put into a mold whose material forming at least the bottom surface is glass or synthetic resin, and then the compound charged into the mold and the water-permeable or gas-permeable A molding step of molding the blend by closely contacting the formwork including the member such that the water-permeable or gas-permeable member faces the blend;
In the state where the compound in the mold and the cover mold are in close contact with each other, the compound is cured, and a curing process for obtaining a cured product of the compound,
And a demolding step of demolding the cured body of the blend from the mold to obtain a cement thin sheet comprising the cured body of the blend. The method for producing a cement-based thin plate according to claim 1, wherein the compound in the kneading step includes (G) an inorganic powder having a brain specific surface area of 4,000 to 10,000 cm ² / g.   The method for producing a cement-based thin plate according to claim 1 or 2, wherein the cement-based thin plate has a thickness of 1 to 6 mm.

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