JPH08189080A - Placing form and concrete structure - Google Patents

Abstract

PURPOSE: To improve strength by filling concrete in a placing form, made of precast concrete formed of high strength concrete with plastic short fiber such as polypropylene kneaded therein, so as to be integrated. CONSTITUTION: A placing form 3 is formed of high strength concrete, so that cracking is hardly generated. The bonding strength of the high strength concrete is enhanced by plastic short fiber, so that bursting is hardly generated even if the form 3 is exposed to fire at the time of a fire or the like. Since the thickness of the form 3 can be thin to the extent of securing necessary strength, a large quantity of plastic short fiber is not required. High strength is obtained since high strength concrete 4 is filled in the form 3, and fluidity is secured to facilitate placing since plastic short fiber is not mixed in the concrete 4. The strength of the placing form 3 to impact and pressure is thereby increased so as to be able to prevent damage at the time of construction, to improve strength and to prevent bursting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving form used for forming a concrete structure such as a pillar, a beam or a wall made of high strength concrete, and a concrete structure formed using the driving form. is there.

[0002]

2. Description of the Related Art In recent years, the use of concrete materials generally called high strength concrete has become popular. High-strength concrete is concrete that has a higher compressive strength than ordinary ordinary concrete, and has already been used in some implementation works with a design standard strength of 420 to 600 kgf /
High strength concrete of about cm ² is used. In the future, it is expected that more concrete will be used. Here, compressive strength 1000 kgf /
Table 1 shows an example of high-strength concrete materials targeted for cm ² .

[Table 1]

By the way, although such high-strength concrete is expected to be used for various building structures due to its design standard strength, the expansion pressure of water vapor contained therein increases during a fire, and It is said that unsteady thermal stress tends to occur and explodes easily.
Some say that they have doubts about its safety. Therefore, as a measure for preventing explosion, it is considered to mix short plastic fibers such as polypropylene into high strength concrete. By doing so, it has been confirmed by experiments that explosions during a fire can be effectively prevented without reducing strength and durability.

[0004]

However, when a concrete structure such as a pillar, a beam or a wall is constructed with high-strength concrete mixed with plastic short fibers, a large amount of plastic short fibers is required. It is not always easy to knead evenly into concrete, and concrete mixed with short plastic fibers is harder and less fluid than concrete without fibers, so the inside of the formwork is difficult when pouring on-site. It is difficult to spread it to every corner, and there are some problems in construction, and effective improvement measures are required.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an effective means capable of preventing explosion of a structure made of high-strength concrete without impairing workability.

[0006]

In order to achieve the above object, the present invention provides a driving mold made of precast concrete, which is used for forming a concrete structure such as a pillar, a beam or a wall, and is made of polypropylene or the like. It is formed from high-strength concrete in which short plastic fibers are mixed. Further, the concrete structure of the present invention is formed in a state in which the driving mold is integrated with the surface layer portion by driving and filling concrete into the concrete driving space formed by the driving mold. It is a thing. In this case, it is desirable to use high-strength concrete as the concrete to be poured and filled into the concrete pouring space.

[0007]

Since the driving form of the present invention is made of precast made of high-strength concrete in which short plastic fibers are kneaded, it has naturally higher strength than that of ordinary concrete and causes cracks and the like. Not only is it difficult, but the plastic short fibers increase the bonding strength of high-strength concrete, making it difficult for explosions to occur even when exposed directly to a fire during a fire. Further, since the thickness of this driving mold may be thin enough to secure the strength required for the mold, a large amount of plastic short fibers is not required and it can be easily manufactured in a precast factory.

Further, in the concrete structure of the present invention, since the high-strength driving form is integrated into the surface layer portion, even if the concrete to be poured and filled in the driving form is ordinary concrete. Since it is reinforced from the outside by the driving form, the entire structure naturally has high strength.
In addition, if the concrete to be poured and filled into the driving form is high-strength concrete, higher strength can be obtained, and at the same time, a high-strength and hard-to-explode driving form is integrated, so that Explosion is prevented from occurring inside.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the driving form and the concrete structure of the present invention are applied to columns will be described with reference to FIGS. As shown in FIGS. 1 and 2, the pillar 1 in the present embodiment has a pair of driving forms 3 and 3 with concave surfaces facing each other around a pillar rebar composed of a main bar 2 and a stirrup 2a. It is formed by pouring and filling high-strength concrete 4 inside.

The driving form 3 is made of high-strength concrete in a channel shape and made of precast concrete, and polypropylene short fibers cut into about 20 mm in the manufacturing stage are mixed and kneaded evenly throughout. There is.

Since the driving form 3 is made of high-strength concrete, it has naturally higher strength and is less prone to cracks and the like than conventional ones made of ordinary concrete, and polypropylene short fibers increase the bonding strength of high-strength concrete. Even if it is raised and exposed directly to a fire during a fire, an explosion is unlikely to occur. Further, since the thickness of the driving mold 3 may be thin enough to secure the strength required for the mold, a large amount of polypropylene short fibers is not required,
It can also be easily manufactured in a precast factory.

The pillar 1 has the driving mold 3 having the above-mentioned properties integrated in the surface layer thereof, and the high strength concrete 4 is poured and filled in the driving mold 3. Not only does it have high strength by itself, but short plastic fibers such as polypropylene are not mixed in the high-strength concrete to be placed inside, so that fluidity is ensured and placing does not become difficult. Then, in the event of a fire, even if the pillar 1 is exposed to the fire, the polypropylene short fibers kneaded in the driving form 3 as described above act to increase the bond strength of the high-strength concrete and prevent the explosion. . Further, although the plastic short fibers are not mixed in the high-strength concrete 4 formed in the driving form 3, the expansion of the high-strength concrete 4 is suppressed by the driving form 3 surrounding the perimeter to prevent explosion inside.

In the above embodiment, polypropylene fibers that have been cut into short pieces are used as the plastic short fibers to be kneaded into the high-strength concrete that constitutes the driving form 3, but the material and shape are not particularly limited. However, any plastic fiber material that can increase the bond strength of high-strength concrete and prevent explosion can be used.

In the above embodiment, the high-strength concrete 4 is poured and filled in the driving form 3, but ordinary concrete may be poured. Even in this case, by using the driving form 3, the strength is higher than that of the ordinary concrete column, and the workability can be improved.

Furthermore, although the concrete structure of the present invention is applied to the pillar 1 in the above-mentioned embodiment, the present invention is not limited to the pillar, and is suitable as shown in FIGS. 3 to 5, for example. It can be applied to beams, walls, floors, stairs, etc. that make up general buildings by adopting various shapes of formwork, as well as civil engineering structures such as dams, bridges, and tunnels.

The driving form 11 shown in FIG. 3 is preliminarily processed into a cylindrical shape according to the shape of the pillar. By using this driving mold 11, the support of the mold becomes easy during construction. The driving form 12 shown in FIG. 4 is for forming a wall, and the plate-shaped driving forms are arranged parallel to each other, and concrete is placed in the gap to form a wall. You can The driving form 13 shown in FIG. 5 is a bending type in which a plurality of flat plates made of precast are juxtaposed and connected by a connecting member (not shown). A plastic material is used for the connecting member, and it is bent as shown in the figure and used as a desired shape for a beam portion or a pillar. In this driving mold, the connecting portion can be bent to be freely deformed into a desired shape, and since individual flat plates are connected, it is easy to support the mold during construction.
In addition, transporting and storing can be easily performed by making the connecting portion flat without bending.

[0017]

As described above, in the driving form of the present invention, since the high strength concrete is kneaded with the plastic fibers, the strength of the driving form against impact and pressure is increased and damage during construction is prevented. Not only can it be prevented, but plastic fibers can act to increase the bond strength of the high-strength concrete and prevent explosion. Also,
In the concrete structure of the present invention, since the above-mentioned driving form is integrated into the surface layer portion, when the inside of the driving form is poured and filled with concrete, it is reinforced from the outside by the driving form to make the whole structure. It can naturally have high strength. In particular, when high-strength concrete is placed inside the driving form, higher strength can be obtained, and since the driving form that has high strength and is hard to explode is integrated in the surface layer, an explosion occurs inside. This can be naturally prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a driving form and a concrete structure of the present invention.

FIG. 2 is an exploded perspective view showing an embodiment of a driving formwork and a concrete structure of the present invention.

FIG. 3 is a perspective view showing an example of an embodiment of a cylindrical driving form.

FIG. 4 is a perspective view showing an example of an embodiment of a plate-shaped driving form.

FIG. 5 is a perspective view showing an example of an embodiment of a folding-type driving form.

[Explanation of symbols]

 1 Pillar (concrete structure) 3, 11, 12, 13 Placing form 4 High strength concrete

Front Page Continuation (72) Inventor Shinji Kada 1-2-3 Shibaura, Minato-ku, Tokyo Shimizu Corporation

Claims (3)

[Claims] 1. A driving form made of precast concrete used for forming concrete structures such as columns, beams, walls, etc., which is made of high-strength concrete in which short plastic fibers such as polypropylene are kneaded. A driving formwork characterized by 2. A concrete structure, such as a pillar, a beam or a wall, formed by using the driving form according to claim 1, wherein concrete is poured into a concrete placing space formed by the driving form. A concrete structure characterized in that the above-mentioned driving form is formed integrally with the surface layer by filling and filling. 3. The concrete structure according to claim 2, wherein the concrete poured into and filled in the concrete placing space is high-strength concrete.