JP2002179446A - Bicomponent fiber comprising synthetic fiber and steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bicomponent fiber comprising a synthetic fiber and steel, which realizes the improvement of resistance to the explosive fracture or the prevention of the exfoliation of the surface layer of a hardened body under a high temperature environment of concrete or mortar, thereby a secondary coating process or a fire-proof plate can be eliminated and the construction cost is reduced and further, which realizes the improvement of the fracture toughness under normal conditions. SOLUTION: The conjugate fiber 1a (1b) is formed by compositing a synthetic polymer material 3a (3b) and steel 2a (2b), added to concrete or mortar for improving the toughness and the resistance to the explosive fracture of the resulting hardened body and has such characteristic that the rate of residual mass when it is heated to 500 deg.C is <=30%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to concrete or mortar used for structures that may be subject to fire, such as buildings and tunnels. More particularly, the present invention relates to concrete or mortar blended with these concretes or mortars. The present invention relates to a composite fiber composed of a synthetic polymer and steel, which is effective for improving toughness at the time of fire, further improving explosion resistance in a fire and preventing surface layer peeling.

[0002]

2. Description of the Related Art Conventionally, special measures have been taken in the case of a tunnel fire in Japanese tunnels. However, the fire of the Tomei Expressway / Nihonzaka Tunnel in 1979 began to raise the issue of tunnel fires. Particularly, in road tunnels, there is a concern that explosion of lining concrete may occur due to high heat caused by vehicle fire in the tunnel. That is, in a high-temperature environment such as a fire, the surface of the concrete tends to explode due to steam pressure, thermal stress, or the like.

[0003] Under the circumstances where measures and standards for tunnel fires have not yet been established as compared with Europe and the United States, some road tunnels in Japan have been designed to prevent explosion while maintaining the fire resistance of lining concrete. For example, a fireproof plate is attached to the surface.

[0004]

However, in order to prevent explosion by attaching a fire-resistant plate in this way, the cost is increased, and the cost of building a road tunnel and the like and maintaining it is soaring. I will. Against this background, designs and construction methods that omit secondary linings and fireproofing plates are being studied for the purpose of reducing construction costs for social capital, but the explosion at the time of fire is prevented and the strength of concrete after fire is reduced. At present, no method has been provided to prevent the decline.

The present invention has been made in view of the above circumstances, and has as its object to harden concrete or mortar in a high-temperature environment in order to reduce the construction cost by omitting a secondary lining or a fireproof plate. It is an object of the present invention to provide a composite fiber made of a synthetic polymer and steel, which makes it possible to improve the explosion resistance of the body and prevent the surface layer from peeling, and also to improve the toughness in normal times.

[0006]

The composite fiber of the present invention comprising a synthetic polymer and steel is added to concrete or mortar to improve the toughness and explosion resistance of the resulting cured product. The present invention provides a means for solving the above-mentioned problem, in which a synthetic polymer material having a residual mass ratio of 30% or less when heated to 500 ° C. is combined with steel.

According to this composite fiber, since it has a synthetic polymer material having a weight retention rate (non-evaporation amount) of 30% or less when heated to 500 ° C., it is mixed with concrete or mortar. Then, when the cured body is placed in a high-temperature environment, even if the amount is small, the volume is quickly reduced to form effective pores serving as holes for water vapor. Therefore, the explosion resistance of the hardened concrete or mortar blended with the composite fiber in a high-temperature environment is improved. In addition, since steel is included, the toughness in normal times is improved, and furthermore, the surface layer separation under a high-temperature environment is prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The composite fiber of the present invention is a composite of a synthetic polymer material having a residual mass ratio of 30% or less when heated to 500 ° C. and steel.

Specific examples of the synthetic polymer material include polypropylene and polyvinyl alcohol (vinylon). Here, as various synthetic polymer materials (organic materials), the weight residual ratio when heated to 500 ° C. is 10 to 10.
There are various types, from 20% to about 80%, but when a material with a residual weight ratio of more than 30% is used, hardened concrete or mortar formed by evaporation of the synthetic polymer material during a fire The water vapor escape hole is not sufficiently formed, and the effect of the composite fiber on explosion prevention becomes insufficient.

On the other hand, if the material has a residual weight ratio of 30% or less when heated to 500 ° C., the volume of the synthetic polymer material corresponding to the volume of the synthetic polymer material before evaporation is reduced by evaporation of the synthetic polymer material. Large pores are formed, and the pores function as steam release holes, thereby exhibiting good explosion resistance.

As the steel, ordinary steel, stainless steel and the like are preferable, and in particular, those made of metal or alloy having alkali resistance are used. As such steels, for example, fibrous steels are conventionally known as those which improve the toughness of concrete or mortar. Thus, in the present invention, by combining such steel with the above-mentioned synthetic polymer material to form a fiber, it is possible to improve both toughness and explosion resistance.

More specifically, the composite fiber of the present invention is shown in FIG.
(A), composite fiber 1a, 1b as shown in (b), FIG.
(A), composite fibers 10a, 10b as shown in (b),
Composite fiber 20 as shown in FIGS. 3 (a), (b) and (c)
a, 20b, 20c, and the composite fiber 30 as shown in FIG.

The composite fiber 1 shown in FIGS. 1 (a) and 1 (b)
a, 1b are steels 2a, 2b each being a solid fibrous form.
And synthetic polymer materials 3a and 3b in which the surfaces of these fibrous steels 2a and 2b are coated in a thin film form. The composite fiber 1a shown in FIG. The composite fiber 1b shown in FIG. 1 (b) is formed in a square cross section.

In order to manufacture these composite fibers 1a and 1b, for example, steels 2a and 2b previously formed into fibers having a circular or square cross section are immersed in a molten synthetic polymer material for a predetermined time. Then pull it up and dry it,
The composite fibers 1a and 1b are obtained by solidifying the synthetic polymer material to form a thin-film coating.

The composite fiber 10 shown in FIGS. 2 (a) and 2 (b)
a, 10b are hollow fibrous steels 11a,
11b and synthetic polymer materials 12a and 12b filled in these hollow portions. The composite fiber 10a shown in FIG. 2A has a circular cross section and FIG.
Is formed in a square cross section.

In order to manufacture these composite fibers 10a and 10b, for example, steels 11a and 11b previously formed into hollow fibers having a circular or square cross section are immersed in a molten synthetic polymer material for a predetermined time. At this time, the hollow portion is filled with the melted synthetic polymer material by, for example, depressurizing one end of the hollow fiber. Thereafter, this is pulled up and dried, and the synthetic polymer material is solidified to obtain composite fibers 10a and 10b.

Each of the composite fibers 20a, 20b and 20c shown in FIGS. 3 (a), 3 (b) and 3 (c) is a fibrous steel having grooves 21a (21b and 21c) formed in the periphery thereof. 2
2a, 22b, 22c and these grooves 21a (21b, 2b
1c) synthetic polymer material 23a, 23b filled in
23c, each having a square cross section. Here, the composite fiber 20a shown in FIG. 3 (a) has a groove 21a formed on one side surface along the length direction of the steel 22a, and FIG. 3 (b)
The composite fiber 20b shown in FIG. 3 has grooves 21b formed on two opposite sides thereof along the length direction of the steel 22b, and the composite fiber 20c shown in FIG.
Is formed by forming grooves 21c on three sides thereof along the length direction of the steel 22c.

In order to manufacture these composite fibers 20a, 20b and 20c, for example, the grooves 21a (21b, 21b
The fibrous steels 22a, 22b, 22c formed in c) are
Immersed in a molten synthetic polymer material for a predetermined time,
1a (21b, 21c) is allowed to sufficiently enter the synthetic polymer material. Then, the composite fibers 20a, 20b are lifted up and dried to solidify the synthetic polymer material to fill the grooves 21a (21b, 21c) with the synthetic polymer materials 23a, 23b, 23c. , 20c.

In the composite fiber 30 shown in FIG. 4, a steel 31 and a synthetic polymer material 32 are both formed to be thin and long in the form of a fiber, and these are alternately laminated to form a fiber having a normal thickness (wire diameter). In the example shown in FIG. 4, slightly thicker steels 31 are respectively arranged on the outermost sides, and three layers of the synthetic polymer material 32 and two layers of the steel 31 are provided inside these.
Each is alternately laminated.

In order to manufacture the composite fiber 30, for example, steel and a synthetic polymer material are respectively formed in a thin film having a predetermined thickness in advance. Next, these are alternately laminated, and in this state, for example, pressure-bonded, or pressure-bonded in a heated state, thereby integrating the laminate. Thereafter, the obtained laminated body is cut into a fiber having a desired size to obtain a composite fiber 30. In addition, in the composite fiber 30 shown in FIG. 4, a total of seven layers were laminated, but the present invention is not limited thereto, and one or more layers of steel and a synthetic polymer material may be used.
It is sufficient that two or more layers are stacked in total.

Such composite fibers 1, 10, 20, 30
As the amount of addition to concrete or mortar,
Although not particularly limited, it is preferably about 0.05 to 1.00% by volume from the viewpoint of workability and strength of concrete and mortar. In addition, these composite fibers 1, 10, 20, 30
Although there is no particular limitation on the dimensions of the concrete or mortar, the diameter is 0.05 mm.
It is preferable that the length is about 2.00 mm and the length is about 5-20 mm.

Incidentally, steel fibers having various projection shapes for improving the adhesion to concrete have been conventionally marketed, but in the present invention, for example, FIGS. 1 (a) and 1 (b) Of course, steel fibers having such projections may be used as the fibrous steels 2a and 2b in the composite fibers 1a and 1b shown in FIG.

The composite fibers 1, 10, 2 shown in FIGS.
0 and 30, the synthetic polymer material 3 having a weight retention rate (non-evaporation amount) of 30% or less when heated to 500 ° C.
When these are mixed with concrete or mortar, even when the amount of the hardened material is small, even if the amount is small, the volume of the hardened material can be reduced quickly, An effective hole is formed as a relief hole for the hole. Therefore, these composite fibers 1, 10, 20, 30
Of hardened concrete or mortar blended with
Explosion resistance in a high temperature environment can be improved.
Moreover, since it has steels 2, 11, 22, and 31,
The toughness in normal times can be improved, and furthermore, surface layer peeling under a high-temperature environment can be prevented.

The composite fibers 1, 10, 20, 3
In the case of 0, the composite fiber 1, 10, 20, 30
When the hardened concrete (structure) of concrete or mortar that uses is placed in a high-temperature environment such as a fire,
By taking a sample from the damaged concrete (mortar) and examining the thermal degradation status of the synthetic polymer material in the sample, the heat receiving temperature of the concrete (mortar) can be estimated. ) Can be used as a guide for repairs.

For example, when polypropylene is used as a synthetic polymer material, and when this polypropylene has disappeared, it is estimated that the temperature of the concrete in that portion has reached 500 ° C. or higher. Therefore, it is possible to propose a repair method in which the concrete in which the polypropylene has disappeared is scraped off at the time of repair, and healthy concrete is beaten again.

The composite fiber of the present invention is shown in FIGS.
Various shapes can be adopted without being limited to the circular cross-sectional shape or the square cross-sectional shape shown in FIG. 4, and various forms can also be adopted as the composite form.

[0027]

As described above, the composite fiber comprising the synthetic polymer of the present invention and steel has a residual weight ratio (non-evaporation) of not more than 30% when heated to 500 ° C. Therefore, when the composite fiber is blended with concrete or mortar, when the cured product is placed in a high-temperature environment, even if the amount is small, the volume is quickly reduced to reduce the amount of water vapor. Form effective voids that serve as relief holes. Therefore, according to this composite fiber, the explosion resistance of the cured concrete or mortar blended with the composite fiber in a high-temperature environment can be improved. Further, since the conjugate fiber also has steel, it is possible to improve the toughness in a normal state and to prevent surface layer peeling in a high-temperature environment.

In the event that the hardened concrete (structure) of concrete or mortar using the composite fiber is placed in a high-temperature environment such as a fire, a sample is taken from the damaged concrete (mortar). By examining the state of thermal degradation of the synthetic polymer material in the sample, this can be used as a measure of repair, and a simple repair criterion can be proposed.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are cross-sectional views for explaining a schematic configuration of an example of a conjugate fiber of the present invention.

FIGS. 2 (a) and 2 (b) are cross-sectional views for explaining a schematic configuration of another example of the conjugate fiber of the present invention.

FIGS. 3A to 3C are cross-sectional views for explaining a schematic configuration of another example of the conjugate fiber of the present invention.

FIG. 4 is a cross-sectional view for explaining a schematic configuration of another example of the conjugate fiber of the present invention.

[Explanation of symbols]

1 (1a, 1b), 10 (10a, 10b), 20 (2
0a, 20b, 20c), 30 ... composite fiber, 2 (2a,
2b), 11 (11a, 11b), 22 (22a, 22
b, 22c), 31 ... steel, 3 (3a, 3b), 12 (1
2a, 12b), 23 (23a, 23b, 23c), 3
1: Synthetic polymer material, 21a, 21b, 21c: groove.

Claims (5)

[Claims] 1. A composite fiber added to concrete or mortar for improving the toughness and explosion resistance of a cured product obtained, and having a mass residual ratio of 30% or less when heated to 500 ° C. A composite fiber comprising a synthetic polymer and steel, wherein a synthetic polymer material and steel are compounded. 2. A composite fiber comprising a synthetic polymer and steel according to claim 1, wherein said steel is solid fibrous, and the surface is coated with a thin film of said synthetic polymer material. . 3. The composite fiber according to claim 1, wherein the steel is a hollow fiber, and the hollow portion is filled with the synthetic polymer material. 4. The synthetic height according to claim 1, wherein said steel is fibrous and has a groove formed in the periphery thereof, and said groove is filled with said synthetic polymer material. Composite fiber composed of molecules and steel. 5. The synthetic polymer and steel according to claim 1, wherein the steel and the synthetic polymer material are both formed in a thin thickness, and they are alternately laminated to form a fiber. Composite fiber consisting of