JPH07206549A - Production of permanently laying mold for highly durable concrete - Google Patents

Abstract

PURPOSE:To obtain a permanently laying mold, improved in durability, weatherability and mechanical strength, by kneading cement, fibers, silica, sand, clay, plasticizer and water and by subjecting the resultant extrusion-molded material to curing at elevate temperatures and pressures. CONSTITUTION:A composition comprising 25-55wt.% of cement, 1-10wt.% of at least one kind of fibers selected from inorganic natural fibers, organic natural fibers and synthetic fibers, 5-30wt.% of sand, 10-40wt.% of silica, 5-30wt.% of clay, 0.1-3wt.% of a plasticizer, and 15-55 pts.wt., based on 100 pts.wt. of the kneaded product, of water, is kneaded for 2-15min, and the resultant kneaded product is put into an extrusion molding machine to conduct a continuous extrusion with a screw in the cylinder to obtain a laying mold 20-50% in water- cement ratio. This laying mold is then fed into an autoclave chamber where the laying mold is subjected to high-temperature and high-pressure curing at 150-200 deg.C for 2-10hr at a rate of temperature rise of 50-80 deg.C/h at a peak temperature of 170-190 deg.C, to obtain the aimed laying mold having 10-25% in porosity and 8-45MPa in flexural strength, and also having projections 11 and recesses 12 on the back surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a permanent buried formwork for concrete, more specifically a concrete having excellent extrusion moldability and high durability, that is, excellent weather resistance and high strength. TECHNICAL FIELD The present invention relates to a method for manufacturing a permanently embedded formwork.

[0002]

2. Description of the Related Art Conventionally, formwork materials generally used in the formwork construction method for buildings and the like have been used on the premise that they are demolded and reused. Plywood and steel lumber called is used. In recent years, molds made of various materials have been used or tried. For example, thin concrete boards, glass fiber reinforced cement boards and other forms, FRP (fiber reinforced plastic) products that are lightweight and aesthetically pleasing, and for the purpose of recycling hard paper waste forms and non-woven fabrics as new forms in recent years. There is also a water-permeable formwork that uses a wooden formwork.

[0003]

However, the formwork as described above has an inherent drawback due to the difference in material, and it is not possible to use it in a permanent formwork such as a wooden formwork or a resin formwork. There is a problem that the fire resistance is poor, and a water-permeable mold or a rigid paper waste mold that uses a non-woven fabric and a wooden mold together is preferable because it has water permeability, but there is a problem with durability that can be used semipermanently. There is also steel material, resin and FR
There is a problem in that a good concrete structure cannot be obtained because the product made of P does not have properties such as water absorption and water permeability and therefore has no function of modifying the concrete to be placed. On the other hand, the use of wooden formwork has been a problem in recent years due to environmental problems, demand for reducing wood resources and shortening the construction method, etc.
Alternative formwork building materials, especially buried formwork, have been demanded.

Therefore, as a result of studying such a problem, the present inventor found that the condition of the formwork material containing cement is that the excess water of the placed concrete is absorbed and the water of the internal concrete is absorbed. It is necessary to reduce the cement ratio, and in order to have such an absorbing effect, it is necessary to make the porosity of the mold material 10% to 25%. In order to make the formwork maintenance-free (no need to hold or manage), excellent weather resistance is essential, and the bending strength of the formwork material is 8 MPa to 25 M.
There are two points that a strength of Pa is required.

Therefore, when the formwork material satisfying these two points was further investigated, a plasticizer was added to a mixture of cement, fiber, silica, sand and clay, and the mixture was kneaded with water and then molded. It was found that an embedded mold can be manufactured under good extrusion moldability, and that a mold obtained by further curing at high temperature and high pressure has excellent performance as an embedded mold. The present invention has been completed here. Therefore, the problem to be solved by the present invention is that it is possible to manufacture an embedded formwork having a porosity of 10% to 25% and a bending strength of 8 MPa or more with good extrusion moldability, high durability, That is, it is an object of the present invention to provide a method for producing a permanent buried formwork for concrete which has excellent weather resistance and high strength.

[0006]

The problems to be solved by the present invention are achieved by the following inventions. (1) A method for producing a permanent buried formwork for concrete having a porosity of 10% to 25% and a bending strength of 8 MPa or more is obtained by kneading a mixture of cement, fiber, silica, sand, clay and water. A method for producing a permanent buried formwork for concrete, which comprises subjecting the kneaded product to extrusion molding, and then subjecting the resulting molded product to high temperature and high pressure curing.

(2) The method for producing a permanent buried formwork for concrete according to the above item 1, wherein the bending strength is 8 MPa to 45 MPa.

(3) 25% by weight to 55% by weight of cement,
Fiber 1% to 10% by weight, sand 5% to 30% by weight,
Concrete according to any of the above items 1 or 2, characterized in that it comprises 10% to 40% by weight of silica, 5% to 30% by weight of clay and 0.1% to 3% by weight of a plasticizer. Manufacturing method for permanent buried formwork.

(4) For concrete according to any one of the above items 1 to 3, characterized in that the fiber is at least one selected from inorganic natural fibers, organic natural fibers and synthetic fibers. Manufacturing method for permanent buried formwork.

(5) The method for producing a permanent buried formwork for concrete according to any one of the above items 1 to 4, wherein the back surface of the formwork is formed in an uneven shape.

The present invention will be described in more detail below. The permanent buried formwork for concrete of the present invention is 10%.
A permanent embedding formwork for concrete having a porosity of -25% and a bending strength of 8 MPa or more is used.
It consists of silica, sand and clay, and after adding a plasticizer to this mixture, kneading it with water and extruding the resulting kneaded product to form an embedded formwork with good moldability. It can be manufactured. Then, the molded product, which is the buried form, is cured at a high temperature and a high pressure to obtain 10% to 2%.
What has a porosity of 5% and a bending strength of 8 MPa or more is obtained, and an embedded formwork excellent in high durability is obtained, and the embedded formwork is integrated with concrete after construction,
Further, a concrete structure having excellent weather resistance and bending strength can be obtained.

By the method for producing a permanent buried formwork for concrete of the present invention, excellent durability can be obtained. This durability includes bending strength, neutralization prevention, salt penetration prevention, frost damage prevention, etc. Weather resistance such as ultraviolet rays, wind and rain, and acid rain 2
It is a kind of effect. Cement, fiber, silica, sand and clay are used as materials for the permanent buried formwork for concrete of the present invention, and a plasticizer is added to these kneaded products in order to improve the filling property and moldability. As this cement, any one of ordinary Portland cement, Portland cement such as early strength Portland cement and super early strength Portland cement, mixed cement such as blast furnace cement, silica cement, fly ash cement, and alumina cement can be used. .

Examples of the fibers include inorganic fibers such as wollastonite and asbestos, natural organic fibers such as pulp and synthetic fibers, and more specifically, the natural organic fibers include NB.
K pulp, LBK pulp, cotton pulp, hemp pulp and other pulp, wood powder, sawdust, cork powder, various fibers, and the like,
Examples of synthetic fibers include vinyl chloride, nylon, polyamide, polyester, polyurethane, vinylon, polyethylene, aramid fiber, and carbon fiber. These fibers may be used in any length, but preferably 1
mm to 20 mm long is preferable, and further 2 mm to 1
A length of 0 mm is preferable. The fiber diameter is 0.0
01 mm to 2 mm is preferable.

The silica used in the present invention may be of any type or obtained by any manufacturing method, and examples thereof include amorphous silica, silica fume, amorphous silica (amorphous silica) and fly ash. The average particle size of these silicas is 0.1 μm to 10 μm.
It is 0 μm. In the present invention, bending strength can be improved by adding these silicas to the cement component. Examples of the sand used in the present invention include river sand, sea sand, and crushed stone. Further, the clay used in the present invention improves the extrusion moldability and the surface property of the obtained embedded form during the production of the embedded form. Examples of such clay include shale clay, kibushi clay, frog eye clay, kaolin and the like.

Cement, fiber, used in the present invention,
The ratio of silica, sand and clay is 25% by weight of cement to 5%.
5% by weight, 1% by weight to 10% by weight of fiber, 5% by weight to 3% of sand
0 wt%, 10 wt% to 40 wt% silica, 5 wt% to 30 wt% clay, preferably 30 wt% to 50 wt% cement, 1 wt% to 5 wt% fiber, 15 silica
% To 30% by weight, 10% to 25% by weight sand, and 10% to 20% by weight clay. If the amount of cement is less than 25% by weight, the strength is lowered, which is not preferable, and if the amount of cement exceeds 55% by weight, the strength is not increased and it is economically disadvantageous. If the fiber content is less than 1% by weight, the reinforcing effect is not so great, and if it exceeds 10% by weight, the strength is rather lowered. If the amount of silica used in the present invention is less than 10% by weight, the bending strength cannot be further increased, and if the amount of silica exceeds 40% by weight, the bending strength tends to be rather weak, which is not preferable. The amount of clay added is 5% by weight
If it is less than the above range, the moldability or surface property is not sufficient, and if the amount of clay added exceeds 20% by weight, the strength of the obtained mold is insufficient, which is not preferable.

When the amount of sand used in the present invention is less than 5% by weight, the cost cannot be essentially reduced. If the amount of sand added exceeds 30% by weight, the bending strength or the strength of the concrete structure becomes weak, which is not preferable.
The amount of water used in forming the kneaded product of the cement, fiber, silica, sand and clay used in the present invention is preferably 20 parts by weight to 55 parts by weight of water with respect to 100 parts by weight of the kneaded product, and The water-cement ratio of the obtained buried formwork may be a normal water-cement ratio, but is preferably 1 in water-cement ratio.
It is 5% to 50%. Further, in the present invention, a plasticizer is added during the formation of the kneaded product, which may be added during the kneading of the kneaded product of cement, fiber, silica, sand and clay, or in advance. After adding a plasticizer to the kneaded product, kneading may be performed. Preferred plasticizers for use in the present invention include methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, polyethylene oxide (PEO), etc., and the amount of these plasticizers added is 0.1 to the kneaded product in any case. Wt% -3
%, And if the amount of the plasticizer added is less than 0.1% by weight, sufficiently good moldability cannot be obtained. On the other hand, if the amount added exceeds 3% by weight, plasticization will proceed too much and molding will not be possible.

The permanent buried formwork for concrete of the present invention is
A plasticizer is added to a mixture consisting of cement, fibers, silica, sand and clay, and water is further added to knead the mixture, and the obtained kneaded product is introduced into a molding form and molded, and then It is manufactured by subjecting the obtained molded product to steam curing. The cement, fiber, silica, sand, clay, plasticizer and water kneaded product can be obtained by sufficiently kneading, but this kneading time is
It takes a relatively short time, and a sufficiently uniform kneaded product can be obtained in 2 to 15 minutes. Furthermore, the cement, the fiber used in the present invention,
The amount of water used when forming a kneaded product of silica, sand and clay is preferably 15 parts by weight to 55 parts by weight of water relative to 100 parts by weight of the kneaded product, and the water cement of the obtained buried formwork. The ratio may be an ordinary water cement ratio, but is preferably 20% to 50% in water cement ratio.

In the method for producing a permanent buried formwork for concrete of the present invention, the kneaded product kneaded as described above is introduced into an extruder and extrusion-molded. This extrusion molding may be an extrusion molding method usually used in this technical field. For example, an extruder is used to extrude the kneaded product from an extrusion die to form a desired shape. The extrusion of this kneaded material is a method of continuously extruding it by a screw in a cylinder. The extruded embedded formwork is then placed in an autoclave chamber and cured at high temperature and high pressure. This high temperature / high pressure curing is carried out at a temperature of 150 ° C. to 200 ° C. and a curing time of 2 hours to 10 hours by sending the embedded formwork to the autoclave chamber. At this time, the temperature rising rate is 50 ° C./h to 80 ° C./h
Therefore, the maximum temperature of 170 ° C to 190 ° C is preferable. This regimen can also be repeated as needed.

In the present invention, the high temperature and high pressure curing promotes the porosity and the bending strength so that the porosity becomes 10% to 25% and the bending strength becomes 8 MPa or more. However, when concrete is poured by having a porosity in this range, the components of the concrete flow into the pores, the formwork and the poured concrete are integrated, and excess water is absorbed to obtain high strength. Therefore, a product having excellent weather resistance can be obtained. Therefore, when the porosity is less than 10%, the components of the concrete containing water do not sufficiently flow in, so that the performance of the form becomes insufficient, and when the porosity exceeds 25%, the component material of the form becomes small. Therefore, sufficient durability cannot be obtained. The size of pores or pores formed in the present invention is preferably 10Å to 2,500Å in diameter. Furthermore, in the method for producing a permanent buried formwork for concrete of the present invention, 8 MPa or more, preferably 8 MPa to 45 MP.
A preferred buried form having a bending strength of a is obtained.

The permanent buried formwork for concrete used in the present invention is produced in any shape, and the surface in contact with the poured concrete may be flat or uneven, but is preferably It is good to have unevenness. When the formwork has irregularities, it is preferable to place the reinforcing bars for the cast concrete in the depressions. Examples of the shape of the unevenness include a corrugated shape, a zigzag shape, a Mt. Fuji shape, and a U-shape.
The concave portion and the convex portion may be symmetrical or asymmetrical, or may be a combination of these shapes. Aggregates such as sand and gravel can be added to the mold material used in the present invention, and if necessary, additives or admixtures well known in the art can be added.

[0021]

In the present invention, after the mixture of cement, fiber, silica, sand, clay, and water is kneaded, a plasticizer is added to the mixture when the mixture is extruded and the mixture is kneaded. The product is molded with good moldability. Then, since the embedded formwork, which is the molded product, was cured at high temperature and high pressure, the porosity was easily 10% to 25% and the bending strength was 8M.
An embedded formwork that satisfies the condition of Pa or higher can be easily obtained,
Moreover, by using this buried formwork, it is possible to obtain a high-strength concrete structure by placing the concrete and then integrating the formwork and the concrete.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 The buried form shown in the partial perspective view of FIG. 1 was manufactured by the manufacturing method of the present invention, and concrete was poured using this to form a concrete structure. In FIG. 1, the buried formwork 1
Has a convex portion 11 and a concave portion 12 on the back surface of the embedded formwork 1. The kneaded product for formwork is 41 wt% cement, 10 wt% sand, fiber (carbon fiber (pitch type), diameter 0.0145 mm, length 10 mm, aspect ratio 69
0) 2% by weight, 15% by weight of silica (average particle size 10 μm), 10% by weight of clay, 2.0% by weight of methylcellulose as a plasticizer and 20% by weight of water were mixed, and the mixture was kneaded for 6 minutes to obtain a uniform mixture A kneaded product was obtained. Then, the material for the mold made of this kneaded material is extruded and molded to have a width of 300 mm,
An embedded formwork 1 having a thickness (convex portion) of 25 mm and a length of 3,000 mm was obtained. The fillability and extrusion moldability were good enough. The molded product was loaded into the autoclave chamber and the temperature was adjusted to 179
It was cured at ℃ for 5 hours. The buried formwork 1 thus obtained was more excellent in weather resistance and strength and had high durability.

As shown in the partial perspective view of FIG. 2, using the buried formwork 1 thus obtained, concrete 2
Was cast to prepare a sample of a concrete structure. At this time, the reinforcing bars 3 were arranged on the concave portion 12 of the buried form 1 and on the outer surface side of the concrete 2. A durability test was conducted using this sample, and the results are shown in Table 1. As a comparative example, a concrete mold was used, and concrete was cast into this mold to form a concrete structure. The strength was calculated from the coefficient of restitution of the Schmidt hammer.

[0025]

[Table 1]

As is clear from Table 1, the embedded formwork obtained by the manufacturing method of the present invention has a large bending strength, and therefore the concrete structure using this embedded formwork begins to have strength and is excellent in weather resistance. ing.

Example 2 The procedure of Example 1 was repeated except that cement, fiber, silica, sand and clay were mixed, methyl cellulose and water were added to the mixture, and the mixture was kneaded to produce a kneaded product. A buried formwork was formed in the same manner as in Example 1, and then a concrete structure was prepared in the same manner as in Example 1. The embedded formwork thus obtained was excellent in weather resistance and bending strength and had high durability. The concrete structure was similarly excellent in weather resistance and strength.

[0028]

EFFECT OF THE INVENTION In the method for manufacturing an embedded formwork of the present invention, a plasticizer is added to a mixture of cement, fiber, silica, sand, clay and water, and the mixture is kneaded and then extruded, resulting in good extrusion. Molded under the influence of sex. Then, by aging at high temperature and high pressure, it is possible to easily manufacture an embedded formwork that has a porosity of 10% to 25% and a bending strength of 8 MPa or more, and is therefore excellent in weather resistance for concrete. A concrete structure in which a permanent buried form can be obtained and concrete is poured using this buried form is a highly durable concrete structure with high strength and excellent weather resistance due to the integration between the form and concrete. This is a particularly remarkable effect of being obtained.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing a permanent buried formwork for concrete of the present invention.

FIG. 2 is a partial perspective view showing a concrete structure using the permanent buried formwork for concrete of the present invention.

[Explanation of symbols]

 1 Embedded formwork 2 Casting concrete 11 Recessed portion 3 Reinforcing bar 12 Convex portion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C04B 28/02 E04B 1/16 C 7121-2E 2/86 A F // (C04B 28/02 14 : 38 Z 16:02 Z 16:06 Z 14:10) Z (72) Inventor Yukinori Kawahara 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi Materials Corporation Cement Research Institute

Claims (5)

[Claims] 1. A method for producing a permanent buried formwork for concrete having a porosity of 10% to 25% and a bending strength of 8 MPa or more, wherein a mixture of cement, fiber, silica, sand, clay, a plasticizer and water is added. A method for producing a permanent buried formwork for concrete, which comprises kneading, extruding the obtained kneaded product, molding, and then curing the obtained product at high temperature and high pressure. 2. The method for producing a permanent buried formwork for concrete according to claim 1, wherein the bending strength is 8 MPa to 45 MPa. 3. Cement 25% to 55% by weight, fiber 1% to 10% by weight, sand 5% to 30% by weight, silica 10% to 40% by weight, clay 5% to 30% by weight.
And 0.1% to 3% by weight of a plasticizer, The method for producing a permanent buried formwork for concrete according to any one of claims 1 and 2. 4. The permanent embedding for concrete according to claim 1, wherein the fiber is at least one selected from inorganic natural fibers, organic natural fibers and synthetic fibers. Formwork manufacturing method. 5. The method for producing a permanent buried formwork for concrete according to claim 1, wherein the backside of the formwork is formed in an uneven shape.