JP2001220190A - S-shaped steel fiber for reinforcing concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an S-shaped steel fiber for reinforcing concrete having the toughness characteristic and balancing characteristic greater than the conventional both ends-hooked steel fiber and with the manufacturing cost lowered and application efficiency improved by suppressing the mixing ratio of the steel fiber in concrete. SOLUTION: Both ends of a steel fiber are formed into the shape of an S with a radius of curvature of (r) to form the S-shaped parts on both ends in the opposite direction to each other. Further, a central S-shaped part is formed in the center with a radius of curvature of (r') or a central inclined part is formed at a bending angle αof >=45 deg. to <90 deg., and the steel fiber has an almost S-shaped appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel fiber (steel fiber) to be mixed in concrete at a constant ratio in order to improve the strength and toughness of concrete.

[0002]

2. Description of the Related Art Conventionally, in order to improve the strength and toughness of concrete, mortar, and the like, steel fibers having various shapes and sizes have been mixed into the concrete or mortar, and the strength and toughness have been increased by using the reinforcing fibers together. To improve toughness,
They tend to be used instead of rebar.

[0003] Among the steel fibers, the following shapes are generally used at present. A corrugated steel fiber having a thickness of about 0.2 to 0.5 mm, a width of about 0.5 to 1.3 mm, a length of about 25 to 50 mm, and a thin plate cutting method. 0.5mm thick, 0.5mm wide, 20-50mm long
About indented steel fiber by sheet cutting method. An indented steel fiber having a diameter of about 0.6 to 0.7 mm and a length of about 25 to 50 mm, obtained by a steel wire cutting method. A steel fiber with a diameter of 0.6 to 0.8 mm and a length of about 30 to 60 mm, and both ends hook-shaped by a steel wire cutting method. Bundled steel fiber with a diameter of 0.6 to 0.8 mm and a length of about 30 to 60 mm, both ends hooked by a steel wire cutting method. Dog bone type steel fiber with a diameter of about 0.4 to 0.5 mm and a length of about 20 to 40 mm, obtained by a dissolution extraction method.

The materials used are SPCC, SWM-
B, SUS and the like are generally used.

[0005]

As described above, various steel fibers have been researched and developed by various steel material manufacturers in order to improve the strength and toughness of concrete. Both-end hook-type steel fibers are generally regarded as superior in terms of toughness properties.

However, the hook shape of the both-end hook-type steel fiber is such that the hooks are formed only in one direction and are asymmetrical in the vertical and horizontal directions, so that the toughness characteristic is also asymmetric with respect to the load from above and below the concrete. There was a problem that the balance could not be obtained. Although there is a method of improving the mixing ratio of steel fibers in order to improve the above problem, other problems such as an increase in manufacturing cost and a decrease in construction efficiency occur.

The present invention has been made in view of the above-mentioned problems, and has toughness characteristics and balance characteristics more than those of conventional double-ended hook-type steel fibers, and suppresses the mixing ratio of steel fibers in concrete. An object of the present invention is to provide an S-type steel fiber for concrete reinforcement, which can reduce the manufacturing cost and improve the construction efficiency.

[0008]

In order to solve the above-mentioned problems, in the S-type steel fiber for concrete reinforcement according to the present invention, both ends of the S-shaped steel fiber formed in an S-shape with a radius of curvature r at opposite ends are opposite to each other. The steel fiber is further formed with an S-shaped central S-shaped portion having a radius of curvature r ′ at the center of the steel fiber or a central inclined portion having a bending angle α of 45 ° or more and less than 90 °. The steel fiber is formed so that the external shape of the steel fiber is substantially S-shaped.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a first embodiment of an S-shaped steel fiber for concrete reinforcement according to the present invention, and FIG. 2 is a view in which the height h1 of the S-shaped portion at both ends and the height h2 of the central S-shaped portion in FIG. It is a figure showing a state. FIG. 3 is a view showing a second embodiment of the S-type steel fiber for concrete reinforcement according to the present invention. Further, FIG. 6 is an enlarged view of the S-shaped portions at both ends of the concrete reinforcing S-type steel fiber of the present invention.

As shown in FIGS. 1, 2 and 6, S-shaped portions 2a, 2a at both ends of the steel fiber 1 formed in an S-shape with a radius of curvature r are formed so as to be opposite to each other. Further, an S-shaped center S with a radius of curvature r 'is provided at the center of the steel fiber 1.
The S-shaped steel fiber for concrete reinforcement of the present invention is formed by forming the character portion 2b and forming the steel fiber 1 so that the external shape of the steel fiber 1 becomes substantially S-shaped. In FIG. 2, since the height h1 of the S-shaped portions at both ends is equal to the height h2 of the center S-shaped portion, the radius of curvature r 'of the center S-shaped portion 2b is equal to the radius of curvature r of the S-shaped portions 2a at both ends. I don't care.

Alternatively, as shown in FIG. 3, both ends of the steel fiber 1 are formed in an S-shape with a radius of curvature r at both ends.
a are formed so as to be opposite to each other, and a central inclined portion 2c having a bending angle α of 45 ° or more and less than 90 ° is formed at the center of the steel fiber 1, and the appearance of the steel fiber 1 is substantially S-shaped. It is formed into a mold to obtain an S-shaped steel fiber for concrete reinforcement of the present invention.

In the above steel fiber 1, the total length L of the steel fiber 1
1, about 30 to 80 mm, length L2 of both ends S-shaped parts 2a, 2a about 3 to 6 mm, height h of both ends S-shaped parts 2a, 2a
When 1 is about 1 to 3 mm and the height h2 of the central S-shaped part 2b or the central inclined part 2c is about 2 to 6 mm, the entanglement of the steel fibers 1 in the concrete is reduced and the friction resistance against stress is maintained. Is also in a suitable state.

FIG. 4 is a view showing various cross-sectional shapes of the S-type steel fiber for concrete reinforcement of the present invention, wherein (a) is a round shape, (b) is a square shape, (c) is a chamfered square shape (d). Indicates a rectangular shape (e) and a chamfered rectangular shape, and the cross-sectional shape is not particularly limited and may be various shapes.

FIG. 5 is a diagram in which the S-type steel fibers for concrete reinforcement of the present invention are connected by a water-soluble adhesive.
If a large number of the steel fibers 1 are arranged in parallel and are connected by a water-soluble adhesive, it becomes efficient during storage and construction.
If the steel fiber 1 in this state is put into concrete and agitated, the water-soluble adhesive is easily dissolved, and the steel fiber 1 is dispersed and uniformly dispersed in the concrete.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
When a bending toughness test was carried out by mixing the concrete at a certain ratio into the concrete, it was found that both the 3-day concrete and the 28-day concrete had toughness characteristics and balance characteristics better than conventional double-ended hook-type steel fibers. The result was obtained.

The reason for this is considered that the S-type steel fiber of the present invention has a central S-shaped portion 2b or a central inclined portion 2c at the center thereof and therefore has a larger contact area with concrete than the conventional double-ended hook type steel fiber. Can be Also,
It is also considered that the S-type steel fiber of the present invention has a well-balanced up / down / left / right symmetrical shape, whereas the hook portion of the conventional double-ended hook-type steel fiber has an up / down / left / right asymmetric shape in which hooks are formed only in one direction. Further, it is considered that the concrete and the S-type steel fiber were surely integrated for the above-mentioned reason, making it hard to come off.

[0017]

As described above, by mixing the S-type steel fiber for concrete reinforcement of the present invention into concrete, it is possible to have a toughness characteristic and a balance characteristic higher than that of the conventional double-ended hook type steel fiber. In addition, when a certain standard specification is satisfied, the mixing ratio of steel fibers in the concrete can be suppressed, and the effects of reducing manufacturing costs and improving construction efficiency can be achieved.

[Brief description of the drawings]

FIG. 1 is a first view of an S-type steel fiber for concrete reinforcement according to the present invention.
It is a figure showing an example.

FIG. 2 is a diagram showing a state in which the height h1 of the S-shaped portions at both ends and the height h2 of the central S-shaped portion in FIG. 1 are equal.

FIG. 3 shows a second example of the S-type steel fiber for concrete reinforcement according to the present invention.
It is a figure showing an example.

FIG. 4 is a view showing various cross-sectional shapes of an S-type steel fiber for concrete reinforcement of the present invention.

FIG. 5 is a diagram in which S-type steel fibers for concrete reinforcement of the present invention are connected by a water-soluble adhesive.

FIG. 6 is an enlarged view of an S-shaped portion at both ends of the S-type steel fiber for concrete reinforcement of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel fiber 2a Both ends S-shaped part 2b Central S-shaped part 2c Central inclined part

Claims (2)

[Claims] An S-shaped end (2a, 2a) formed at both ends of a steel fiber (1) in an S-shape with a radius of curvature r is formed so as to be opposite to each other. ), An S-shaped central S-shaped portion (2b) with a radius of curvature r ′ is formed at the center of
An S-shaped steel fiber for concrete reinforcement, wherein the steel fiber (1) is formed so as to have an approximately S-shaped appearance. 2. An S-shaped end (2a, 2a) formed at both ends of a steel fiber (1) in an S-shape with a radius of curvature r so as to be opposite to each other. ), A central inclined portion (2) having a bending angle α of 45 degrees or more and less than 90 degrees
(b) The steel fiber (1) is formed so that the appearance of the steel fiber (1) is substantially S-shaped.