JP5758755B2 - Method for producing concrete member - Google Patents

Description

The present invention relates to the production how concrete member.

  Although high-strength concrete is composed of a dense concrete structure, it has high design standard strength, but in the event of a fire, it expands due to residual moisture and water vapor inside, and the surface of the concrete structure is scale-like. Peeling phenomenon (explosion) may occur.

  For this reason, many methods for producing concrete members for the purpose of preventing explosion of high-strength concrete have been developed.

  For example, as shown in Patent Document 1, the present applicant forms a hole by irradiating the surface of a hardened concrete body with laser light, so that residual moisture and water vapor inside the hardened concrete body are discharged during a fire. We are developing a method for preventing explosion of concrete.

  Moreover, as shown in patent document 2, the organic fiber which melts | dissolves at the time of a fire is mixed in concrete beforehand, and an organic fiber melt | dissolves at the time of a fire and a pore is formed in a hardened concrete body. There is also disclosed a method for preventing explosion of concrete in which residual moisture and water vapor are discharged.

JP2003-300787A JP 2004-224616 A

  The explosion prevention method for forming a hole in a hardened concrete requires time and labor for forming the hole separately after concrete curing. In addition, it takes time and expense to separately prepare equipment such as a laser oscillation device.

  In addition, the hardened concrete mixed with organic fibers takes time from the time of the fire to the time when the organic fibers melt and form pores. There was concern.

Therefore, the present invention aims to provide a manufacturing how possible with concrete member to form a simple and inexpensive high-quality concrete member.

In order to solve the above-mentioned problems, the method for producing a concrete member of the present invention includes a placing step of placing high-strength concrete containing synthetic resin fibers on a mold, and curing the high-strength concrete in the mold. Then, a mold curing process for forming a hardened concrete body, a first curing process for curing the hardened concrete body at a temperature higher than room temperature, and a second curing process for performing dry heating curing after the first curing process. In addition, in the second curing step, the moisture of the surface portion of the hardened concrete body is removed and the synthetic resin fiber contained in the surface portion is melted.
In addition, it is preferable that the surface portion is in a range including the covered concrete portion.

  According to such a method for manufacturing a concrete member, it is only necessary to perform drying and heating curing only on the surface portion, and therefore, the manufacturing period can be shortened compared to the case of performing drying and heating curing to the center of the concrete member. .

When the synthetic resin fiber on the surface portion is melted, voids are formed in the surface portion in advance, so that it is possible to discharge water vapor or the like in the initial fire, and the expansion of the concrete surface is suppressed.
Moreover, since the moisture in the concrete on the surface portion is removed, even if heated in the event of a fire, expansion due to residual moisture and water vapor is suppressed. Therefore, the amount of synthetic resin fibers mixed in can be reduced, and the strength of the concrete can be improved.

  In the case of preventing raindrops or the like from entering the concrete member from the outside, the second curing step is a finishing step for applying a finishing paint for exterior that has high waterproofness and low moisture permeability to the surface of the hardened concrete body. It is desirable to do this later.

According to the method for producing a concrete member of the present invention, a high-quality concrete member can be formed easily and inexpensively .

It is sectional drawing which shows the concrete member which concerns on this embodiment.

Embodiments of the present invention will be described below.
As shown in FIG. 1, the concrete member 1 of the present embodiment includes a hardened concrete body 2 containing synthetic resin fibers, a reinforcing bar 3 arranged inside the hardened concrete body 2, and a surface of the hardened concrete body 2. The exterior finishing coating material 4 is provided.

The covered concrete portion (surface portion) 21 of the hardened concrete body 2 is dried (the amount of water is small) compared to the core portion 22 (portion surrounded by the reinforcing bars).
The covered concrete portion 21 has a number of cavities (not shown) formed by melting synthetic resin fibers.

  The hardened concrete body 2 is configured by hardening high-strength concrete including at least a binder, water, fine aggregate, coarse aggregate, and synthetic resin fibers.

  Although the material used for a binder is not limited, For example, what contains portrant cement and admixtures, such as fly ash and silica fume, may be used.

  Although the material which comprises a synthetic resin fiber is not limited, In this embodiment, the polypropylene fiber which melts | melts at the temperature of about 170-180 degreeC is used. The mixing amount of the synthetic resin fiber is not limited. For example, it may be mixed with the concrete mixture so that the outer volume ratio is 0.5% to 0.6%.

In addition to the synthetic resin fiber, steel fiber may be mixed in the high-strength concrete. As the steel fiber, a high-tensile steel fiber having a tensile strength of 2000 N / mm ² or more, an amorphous steel fiber, a stainless fiber, or the like may be used.

The reinforcing bars 3 are arranged inside the hardened concrete body 2 with a predetermined concrete covering thickness.
The diameter of the reinforcing bar 3 is appropriately determined.

The exterior finish coating material 4 is made of a material having high waterproof properties and low moisture permeability.
In this embodiment, a material having a water permeability of 0.5 ml or less in the water permeability test of the JIS A6909B method and a moisture permeability of 100 g / m ² · 24 h or less in the moisture permeability test of JISZ0208 is employed. The exterior finish coating material 4 is not limited to this.

  The method for producing a concrete member of the present embodiment includes a kneading step, a placing step, a mold curing step, a first curing step, a second curing step, and a finishing step.

  The kneading step is a step in which steel fibers and polypropylene fibers are kneaded into a concrete mixture produced by cement, an admixture, fine aggregate, coarse aggregate, water and the like.

The kneading step of the present embodiment includes dry kneading in which the powder part of the concrete mixture is kneaded, wet kneading in which a liquid part (water or the like) is added to the powder part kneaded by dry kneading, and wet kneading. Fiber kneading in which fibers (steel fibers and polypropylene fibers) are put into a concrete mixture kneaded by kneading and kneaded.
In addition, the kneading method and procedure in the kneading step are not limited and may be appropriately performed.

The placing step is a step of placing high-strength concrete (fresh concrete) containing synthetic resin fibers in a mold formed in a shape corresponding to the shape of the concrete member 1.
A predetermined bar arrangement is made in advance in the mold.

The mold curing process is a process in which the hardened concrete body 2 is formed by curing in the mold until a predetermined strength is developed in the high-strength concrete.
In this embodiment, it is cured at room temperature (about 20 ° C.) for about 1 to 2 days. In addition, the period of a mold curing process, temperature, etc. are not limited.

The first curing process is a process of curing the hardened concrete body 2 at a temperature higher than room temperature.
Prior to the first curing process, the hardened concrete body 2 formed by the mold curing process is demolded.

  In the first curing step, the basic structure is constructed by curing the concrete hardened body 2 at a temperature higher than normal temperature. Specifically, steam curing at about 90 ° C. is performed using a steam curing tank, or autoclave curing at about 180 ° C. and about 10 atmospheres is performed using an autoclave tank. Note that steam curing and autoclave curing may be combined.

When curing using the heat of hydration of cement by heat insulation curing at the stage of the mold curing process, this corresponds to the first curing process. In addition, when it is determined that the basic structure can be sufficiently constructed in the mold curing process, this mold curing process corresponds to the first curing process.
The curing temperature, atmospheric pressure, and holding time in the first curing step are not limited to the above conditions, and may be set as appropriate. Moreover, heat insulation curing may be performed in the mold curing process, and further, high temperature curing or high temperature high pressure curing may be performed.

A 2nd curing process is a process of performing dry heating curing with respect to the concrete hardening body 2 after a 1st curing process.
In the second curing step, moisture in the covered concrete portion 21 of the hardened concrete body 2 is removed and the synthetic resin fibers contained in the covered concrete portion 21 are melted.

In the present embodiment, the second curing process is performed under a temperature environment of about 200 ° C.
The curing time in the second curing process is a time necessary for drying the covered concrete portion 21. What is necessary is just to set this curing time based on the test kneading construction implemented beforehand, for example. Moreover, you may measure the drying condition of the covering concrete part 21 by embedding a sensor in the hardened concrete body 2. FIG.

  The finishing step is a step of applying an exterior finishing coating material to the surface of the hardened concrete body 2 after the second curing step.

  As mentioned above, according to the manufacturing method of the concrete member of this embodiment, since dry heating curing is implemented only about the covering concrete part 21 of the concrete member 1, when carrying out dry heating curing with respect to the whole concrete member 1 Compared with, the curing period can be shortened. Therefore, the concrete member 1 can be manufactured easily and quickly.

  In addition, when dry heating curing is applied only to the concrete portion 21, the synthetic resin fibers contained in the core portion 22 remain without melting, and thus the core portion 22 is formed with no void and densely. Therefore, strength reduction at the core portion 22 is suppressed, and a higher quality concrete member 1 can be manufactured.

Moreover, since the covering concrete part 21 of the concrete member 1 has moisture removed, expansion due to residual moisture or water vapor can be suppressed.
Further, since the covered concrete portion 21 has a cavity formed by melting the synthetic resin fiber, even if water vapor is generated inside the concrete member 1 during a fire or the like, it is absorbed into the cavity. As a result, the concrete member 1 can be prevented from expanding.

  Moreover, since the water | moisture content of the covering concrete part 21 is removed by dry heat curing, the intensity | strength of the covering concrete part 21 can be raised.

  Further, if the moisture in the covered concrete portion 21 is removed in advance, the amount of water vapor generated at the time of the fire is reduced, so that the number of cavities necessary for absorbing the water vapor at the time of the fire is reduced. That is, it is economical because the amount of the synthetic resin fiber contained in the high-strength concrete can be reduced. Further, the strength of the concrete member 21 can be further increased by reducing the amount of the synthetic resin fiber.

Since the exterior finish coating material 4 made of a material having high waterproofness and low moisture permeability is applied to the surface of the concrete member 1, it is possible to prevent moisture from penetrating into the concrete member 1 from the outside. . For this reason, carbon dioxide and chloride are prevented from penetrating into the interior, and durability is maintained.
In addition, since the water | moisture content of the concrete part 1 is previously removed from the concrete member 1, the quantity of the water vapor | steam generated inside concrete also decreases. Therefore, it becomes possible to use a material with low moisture permeability as the exterior finish coating material 4 and to prevent the inflow of humidity from the outside.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and the above-described constituent elements can be appropriately changed without departing from the spirit of the present invention.

  For example, the method for producing a concrete member according to the present invention and the purpose of use of the concrete member are not limited.

Moreover, although the said embodiment demonstrated the case where the water | moisture content of the covering concrete (surface) part 21 of the hardened concrete body 2 was removed and the synthetic resin fiber was fuse | melted, dry heat curing entered the core part 22 for a while. You may carry out to the position.
If the hardened concrete body 2 is unreinforced, the thickness of the surface portion may be set as appropriate.

  Moreover, what is necessary is just to apply | coat the finishing coating material 4 for exteriors as needed.

  Hereinafter, the result of the experiment implemented in order to confirm the effectiveness of the high strength concrete which concerns on this embodiment is shown.

  In this experiment, drying and heating curing was performed on a hardened concrete having a square cross section of 400 × 400 mm and a hardened concrete having a square cross section of 1000 × 1000 mm, and each hardened concrete was dried to the center of the cross section. The drying time and the drying time when the concrete covering thickness (50 mm from the surface) was dried were measured and compared.

In addition, dry heat curing was implemented at the temperature of about 200 degreeC.
The experimental results are shown in Table 1.

As a result of the experiment, when the cross-sectional shape is 400 mm square, it takes 67 hours to dry the entire member, whereas it takes 64 hours to dry the part 50 mm from the surface, which can be shortened by 3 hours.
Also, when the cross-sectional shape is 1000 mm square, it takes 121 hours to dry the entire member, whereas it takes 77 hours to dry from the surface to the 50 mm portion, which can shorten 44 hours (36%). is there.

  Therefore, a high-quality concrete member can be easily provided by the concrete member manufacturing method and the concrete member according to the present embodiment.

DESCRIPTION OF SYMBOLS 1 Concrete member 2 Hardened concrete 21 Covered concrete part (surface part)
22 Core part 3 Reinforcing bar 4 Finishing paint for exterior

Claims (1)

A placing step of placing high-strength concrete containing synthetic resin fibers on a mold,
A mold curing process for curing the high-strength concrete in a mold to form a hardened concrete,
A first curing step of curing the hardened concrete body at a temperature higher than room temperature;
A second curing step of performing drying and heating curing after the first curing step, and a method for producing a concrete member,
In the second curing step, the moisture of the surface portion of the hardened concrete body is removed and the synthetic resin fibers contained in the surface portion are melted.

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