JPH0760731A - Production of fiber-reinforced cement composite material - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced cement composite material producing method for preventing fibers from floating by vibrating a form at the time of infiltration of a cement slurry and effectively exhibiting a reinforcing action by the fibers on the tensile stress side. CONSTITUTION:High-strength fibers 2 are spread on a bottom part of a form 1. Thereon, steel fibers 4 are spread. Thereafter, mortar 3 or the like is cast into the form 1. By vibrating the form 1, the fibers or the like are impregnated with the cement slurry.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a fiber-reinforced cementitious composite material.

[0002]

2. Description of the Related Art Conventionally, a method of laying steel fiber (SF) in a mold in advance and impregnating it with cement slurry to form steel fiber reinforced concrete (SFRC) has been put into practical use. In the case of ordinary steel fiber reinforced concrete that is mixed in advance, the amount of fibers mixed is limited to 2% by volume, but according to the above method, the steel fiber mixture ratio of SFRC composite is 18% by volume. It is said that it is possible to raise it to%.

On the other hand, it has also been attempted to handle high-strength fibers (carbon fiber CF, aramid fiber AF, vinylon fiber VF, etc.) having a higher tensile strength than steel fibers, and as with steel fibers, they are treated as high-strength fibers. Vibration is applied to the formwork to mix with mortar (concrete).

[0004]

[Problems to be Solved by the Invention] However, carbon fiber C
In the case of high-strength fibers such as F, aramid fiber AF, and vinylon fiber VF, as can be seen from Table 1 below, the specific gravity is smaller than that of the cement matrix. Therefore, in FIG.
As shown in (1), when the high-strength fiber 2 and the mortar (concrete) 3 are mixed, the high-strength fiber 2 having a low specific gravity floats up due to the vibration applied to the formwork 1.

Therefore, the obtained cement product 10 which is a fiber-reinforced cementitious composite material has a higher tensile strength than steel fiber, but as shown in FIG. There is a defect that an effective reinforcing effect due to the fiber cannot be obtained, for example, cracks 11 are generated on the side.

Therefore, an object of the present invention is to solve the above problems and to prevent the fibers from floating due to vibration during impregnation of the cement slurry, and to effectively exert the reinforcing action of the fibers on the tensile stress side. It is to provide a method for producing a composite material.

[0007]

In order to achieve the above object, the method for producing a fiber-reinforced cementitious composite material according to the present invention is characterized in that when the fiber-reinforced cementitious composite material is produced, fibers having a specific gravity lower than that of the cementitious matrix are used. Laying in the lower layer of the mold, laying fibers having a heavier specific gravity than the cement matrix, and then pouring or pouring the cement matrix such as cement slurry or mortar into the mold, A frame is vibrated to impregnate these fibers with the cementitious matrix (Claim 1).

Fibers having a specific gravity lower than that of the cement-based matrix are used as high-strength fibers, and fibers having a specific gravity higher than those of the cement-based matrix are used as steel fibers. Alternatively, it may be a combination of laying in the form of mesh fibers and laying steel fibers in the form of short fibers or mesh fibers (claims 2 and 3).

[0009]

The high-strength fibers handled in claims 1 to 3 are those having a higher tensile strength than the steel fibers SF, such as carbon fibers CF, aramid fibers AF, vinylon fibers VF, and the like.
These have a lower specific gravity than the cement-based matrix (see Table 1). On the other hand, the steel fiber SF has a larger specific gravity than the cement-based matrix.

Due to this difference in specific gravity, the high-strength fibers are suppressed by the steel fibers, and even if vibration is applied to the form during impregnation of the cement slurry, the high-strength fibers do not come up due to the vibration. Therefore, the obtained fiber-reinforced cementitious composite material, high-strength fibers are sufficiently dispersed near the tensile side surface layer portion of the member, the reinforcing effect by the fiber when tensile stress acts on the member surface layer portion. Significantly improve. Moreover, since two types of fibers having different properties are used as the reinforcing material, a hybrid effect can be obtained.

As for the form of use of the fibers, as in claim 2 or 3, both the high-strength fibers and the steel fibers can be used as short fibers or long fibers.

[0012]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. (Example 1) As shown in FIG. 1, at the time of molding, first, short fibers 21 made of high-strength fibers 2 such as carbon fibers CF, aramid fibers AF, and vinylon fibers VF were laid in the lower layer of the formwork 1. After laying short fibers 41 made of steel fibers 4 on it, cement slurry or mortar (cement) 3 is poured or poured into the mold 1 to give vibration to the mold 1 to cement the fibers or the like. Impregnate the slurry.

As shown in Table 1, the high-strength fiber 2 has a specific gravity smaller than that of the cement matrix,
The steel fiber 4 has a larger specific gravity than the cement matrix. Therefore, in this way, the high-strength short fibers 21 that try to float up are suppressed by the steel short fibers 41 and do not float up against the vibration given at the time of impregnating the cement slurry. Therefore, in the obtained concrete product 10, the high-strength fibers 2 are relatively evenly dispersed inside and the high-strength fibers 2 are also present at least in the lower side of FIG. When the fiber acts, the reinforcing effect of the fiber appears remarkably. Therefore, it is possible to manufacture the FRC reinforced with the high-strength fiber having a smaller specific gravity than the cement-based matrix by using the impregnation method of the SFRC compound.

Since this manufacturing method uses two types of fibers 2 and 4 having different properties as the reinforcing material, a hybrid effect can be obtained. Also, carbon fiber C
Since fibers such as F, aramid fiber AF, and vinylon fiber VF are used, the problem of rust on the surface of the member does not occur unlike the case of the steel fiber SF.

[0015]

[Table 1] The FRC reinforced with the high-strength fiber having the above advantages can be similarly obtained by the production methods of Examples 2 to 4 below.

(Example 2) As shown in FIG. 2, at the time of molding, first, short fibers composed of high-strength fibers 2 such as carbon fibers CF, aramid fibers AF, and vinylon fibers VF are laid in the lower layer of the formwork 1. What is done is the same as above, but what is laid on it is not the short fibers consisting of the steel fibers 4 but the long fibers in the form of the wire mesh 42. After that, the same as above, the cement slurry or the mortar (cement) 3 is poured or poured into the mold 1, and the mold 1 is vibrated,
The fibers are impregnated with the cement slurry.

(Example 3) As shown in FIG. 3, in molding, first, high strength fibers 2 such as carbon fibers CF, aramid fibers AF and vinylon fibers VF were replaced with long fibers in the form of mesh 22 instead of short fibers. Is laid in the lower layer of the formwork 1.
Then, a short fiber 41 made of steel fiber 4 is laid thereon, and cement slurry or mortar (cement) 3
Is poured or poured into the mold 1, and the mold 1 is vibrated to impregnate the fibers and the like with the cement slurry.

(Embodiment 4) As shown in FIG. 4, at the time of molding, first, high strength fibers 2 such as carbon fibers CF, aramid fibers AF, vinylon fibers VF and the like are formed into a mesh 22 in the same manner as in FIG. It is laid in the lower layer part of the formwork 1 as the long fibers. Then, a long fiber made of steel fiber 4 is laid on it in the form of a wire mesh 42, and cement slurry or mortar (cement) 3 is poured or poured into the mold 1 to give vibration to the mold 1, The fibers are impregnated with the cement slurry.

[0019]

In summary, according to the present invention, the following effects can be obtained. 1) Due to the difference in specific gravity with respect to the cement-based matrix, the high-strength fibers are suppressed by the steel fibers, and even if vibration is applied to the form during impregnation of the cement slurry, the high-strength fibers do not come up due to the vibration. Therefore, the obtained fiber-reinforced cementitious composite material, high-strength fibers are sufficiently dispersed near the tensile side surface layer portion of the member, the reinforcing effect by the fiber when tensile stress acts on the member surface layer portion. Significantly improve.

2) Since two kinds of fibers having different properties are used as the reinforcing material, a hybrid effect can be obtained.

3) It is possible to manufacture an FRC reinforced with high-strength fibers having a specific gravity smaller than that of a cementitious matrix by utilizing the impregnation method of SFRC compound.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the method for producing a fiber-reinforced cementitious composite material of the present invention.

FIG. 2 is a diagram showing a second embodiment of the manufacturing method of the present invention.

FIG. 3 is a diagram showing a third embodiment of the manufacturing method of the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the manufacturing method of the present invention.

FIG. 5 is a diagram showing a conventional method for producing a fiber-reinforced cementitious composite material.

FIG. 6 is a diagram showing cracks on the tensile side of a conventional fiber-reinforced cementitious composite material.

[Explanation of symbols]

 1 Formwork 2 High-strength fiber 3 Cement slurry or mortar 4 Steel fiber 10 Cement product (fiber reinforced cementitious composite material) 11 Crack 21 Short fiber 22 Mesh 41 Short fiber 42 Wire mesh

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Ichifusa Mitani 4-640 Shimoseido, Kiyose-shi, Tokyo Inside Obayashi Corporation Technical Research Institute

Claims (3)

[Claims] 1. When manufacturing a fiber-reinforced cementitious composite material, fibers having a specific gravity lower than that of the cementitious matrix are laid in the lower part of the formwork, and fibers having a heavier specific gravity than the cementitious matrix are laid thereon. Thereafter, the cement-based matrix such as cement slurry or mortar is poured or poured into the mold, and the mold is vibrated to impregnate the fibers with the cement-based matrix. Method for manufacturing a composite material. 2. The fiber reinforcement according to claim 1, wherein the fibers having a specific gravity lower than that of the cement-based matrix are high-strength fibers, and the high-strength fibers are laid in the form of short fibers or mesh fibers. Cement-based composite material manufacturing method. 3. The fiber having a higher specific gravity than the cement-based matrix is a steel fiber, and the steel fiber is laid in the form of a short fiber or a mesh fiber.
Alternatively, the method for producing the fiber-reinforced cementitious composite material according to the item 2.