JP3341938B2 - Formwork for concrete casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for casting concrete when constructing various concrete structures such as dams, piers, roads and buildings in the fields of civil engineering and construction. The present invention relates to a concrete casting formwork to be used.

[0002]

2. Description of the Related Art As a typical concrete casting formwork conventionally used, a wooden plywood (generally referred to as a plywood panel) and a metal board are used. Reinforced with metal ribs (iron,
Stainless steel and aluminum alloy).

[0003] In recent years, concrete casting molds formed from long fiber reinforced thermoplastic resin (generally referred to as "stampable sheets") have been used.
The stampable sheet has features such as light weight, excellent corrosion resistance, good moldability, and high degree of freedom in shape, and is more durable than conventional wooden forms. Its use is considered due to its light weight and light weight. JP-A-2-8459 discloses an example of such a stampable sheet mold. This mold is formed by pressing a polypropylene resin reinforced with a long glass fiber mat into a plate having a predetermined thickness.

[0004]

The following problems have been pointed out in these conventionally used molds, and improvement thereof is strongly desired. That is,
The wooden formwork generally called a control panel has low durability and the number of times of diversion is 2 to 3 times at most. In addition, since the grain is transferred to the surface of the completed concrete, there is a problem that a beautiful structure cannot be made with the bare structure. Furthermore, it is said that a control panel that is disposed of after several uses will lead to the destruction of forest resources from the viewpoint of environmental protection.

[0005] On the other hand, metal molds are tougher and more durable than wooden ones, and the number of diversions is 20 to 3 times.
There is a merit that it can withstand 0 and repeated use. However, iron-made products are susceptible to rust during use, and thus have a problem of so-called "corrosive rust" on the concrete surface, and it takes time to remove rust during conversion. Stainless steel has good corrosion resistance, but, like iron, is of standard size (300mm in width, 1500mm in length, 55mm in height), weighs 15kg per piece, Not only is it difficult to transport the formwork on site,
It is also a problem from a safety perspective. Aluminum products are lightweight and easy to handle, but they are easily scratched, so they are diverted less frequently than iron products, and they are rarely used because they are expensive.

[0006] Since the stampable sheet formwork is basically intended to replace the control panel, it is used by hitting a crosspiece on the side opposite to the concrete casting surface, similarly to the conventional control panel. Therefore, a speedy workability such as a metal mold easily assembled with clips cannot be expected. Further, since the opaque resin is essentially used, the slab has a light transmittance as high as the brightness of the slab, but does not have transparency enough to confirm the filling state of the poured concrete.

[0007] Further, since the filling state of the conventional formwork when the concrete is cast is not visible at all, the defective filling of the concrete around the rebar and the occurrence of avatars due to the voids and the like are made on the spot. I can't confirm. For this reason, if the state of filling of the concrete is not good, it is necessary to repair by hand after removing the formwork, and it is difficult to construct a high-quality concrete structure. There is a big problem that requires much labor.

An object of the present invention is to provide a face plate with such transparency as to allow observation of the filling state and voids of the concrete during casting, and furthermore, a seam at the same time, and a strength capable of withstanding use as a mold. Another object of the present invention is to provide a concrete casting formwork having rigidity. In addition, since it is made of fiber-reinforced thermoplastic resin, it is more durable than conventional plywood forms, can be lighter than metal forms, and is extremely easy to handle. In addition, safety is improved.

[0009]

SUMMARY OF THE INVENTION A concrete casting formwork according to the present invention comprises a face plate and a rib for reinforcement provided along at least the longitudinal direction of the face plate. The ribs are formed from a fiber reinforced thermoplastic resin, and the face plate is made of glass fibers having a length of 10 mm or more.
It is formed of a glass fiber reinforced thermoplastic resin containing 10% by volume or more, and is characterized in that the total light transmittance of the face plate portion is 50% or more and the haze value is 80% or less.

The resin component of the glass fiber reinforced thermoplastic resin as the face plate material used in the present invention includes:
It is sufficient that the resin alone is a thermoplastic resin having high transparency, and is not particularly limited. For example, styrene copolymers such as polystyrene and acrylonitrile styrene, acrylonitrile butadiene styrene, methyl methacrylate and its copolymers, amorphous olefins, transparent grades of polypropylene, polycarbonates, hard chlorides Vinyl etc. can be mentioned.

In order for the face plate to have sufficient strength and rigidity to withstand use as a mold, the length of the glass fiber must be at least one.
A length of 0 mm or more, more preferably 25 mm or more is required. When the length is less than 10 mm, the flexural modulus of the face plate is low, and the face plate is bent by the pressure of the concrete, and as a result, the surface of the concrete structure is wavy. Further, in order to prevent waving, the thickness of the face plate becomes unnecessarily thick, and the weight reduction effect is lost. The glass fiber content is preferably 10% by volume or more and 60% by volume or less, more preferably 20% by volume or more and 50% by volume or less. If it is less than 10% by volume, the physical properties of the face plate will be low, and the same disadvantages as in the case where the fiber length is short will occur. If the content exceeds 60% by volume, not only the transparency required for the face plate is impaired, but also the glass fibers are raised on the surface of the face plate, causing a problem that the fiber pattern is transferred to the concrete surface.

[0012] The filling state and the gap of the concrete during casting,
Furthermore, if transparency can be given to the face plate to enable observation of seams and the like, it will be possible to check the hammering and compacting work of concrete, which had traditionally relied on the intuition and experience of the worker, with the naked eye, The added value of the formwork is very high. Here, in order to have such a transparency that the condition of the concrete can be confirmed, the total light transmittance of the face plate must be 5%.
It is preferable that the haze value is 0% or more and the haze value is 80% or less.

In the present invention, the resin component of the fiber-reinforced thermoplastic resin constituting the ribs can be selected from a wider range because it is not necessary to impart transparency as in the case of the face plate. The above-mentioned styrene copolymers such as polystyrene and acrylonitrile / styrene, acrylonitrile / butadiene / styrene, methyl methacrylate and its copolymer, amorphous olefin, transparent grade of polypropylene, polycarbonate, hard In addition to transparent resins such as vinyl chloride, there may be mentioned, for example, ordinary grades of polypropylene, polyethylene terephthalate, polybutylene terephthalate, nylon 6, nylon 66, polyphenylene sulfide, and the like. It is not something to be done. On the other hand, examples of the reinforcing fiber include, but are not limited to, glass fiber, carbon fiber, wholly aromatic polyamide fiber, and the like, which are generally used as a reinforcing material. Also,
These fibers can be used in combination. However, considering the permissible price as a mold, glass fibers are most preferable among them, and when combined, it is preferable to partially use other reinforcing fibers based on glass fibers. The flexural modulus of the material used for the ribs affects the bending stiffness of the form, and affects the form deflection that occurs when the concrete is cast. In order to significantly reduce the weight compared to a conventional metal mold, the bending elastic modulus of the material used for the rib is preferably at least 10 GPa, more preferably 20 GPa or more. The method of arranging the reinforcing fibers is not particularly limited, and the type of the resin and the type and the content of the reinforcing fiber are set so that the bending elastic modulus is 10 GPa or more by the combination of the reinforcing fiber and the resin described above. The orientation angle or the like may be determined. In order to extract the properties of the reinforcing fiber most efficiently, a unidirectional reinforcing material in which reinforcing fibers are aligned in one direction can be mentioned as a preferable example.

In the present invention, it is preferable to use a means for attaching the rib to the face plate so as not to affect the concrete casting surface. Simply, the face plate and the rib can be attached with an adhesive. Further, it is possible to use a simple fastening material such as a pin joint so that it can be easily detached. As another method for easily attaching and detaching the face plate and the rib, a method of bonding the face plate to the rib with a hot-melt adhesive can be used. When a hot-melt adhesive is used, the face plate can be easily separated from the ribs by reheating the mold due to its thermal properties, and only the damaged face plate can be replaced. However, in order to increase the structural strength of the mold, it is effective to use the same type of resin for the face plate and the rib and to integrally mold the face plate and the rib.

[0015]

When poor filling of concrete or avatars due to voids occur, it is necessary to repair the mold manually after removing the mold, resulting in an increase in the total construction cost. In the present invention, from such a viewpoint, the total light transmittance of the face plate portion is set to 50% or more and the haze value is set to 80% or less. A face plate that satisfies this condition makes it possible to observe the filling state of the concrete during casting, so that defective filling and voids can be found before the concrete hardens. It is possible to take measures such as applying a vibrator near the defective portion.

[0016]

By using the concrete casting formwork of the present invention, the problems of the conventionally used plywood formwork, metal formwork and stampable sheet formwork can be at a glance. Can be solved. That is, by using the fiber-reinforced thermoplastic resin for the face plate and the rib, the weight can be significantly reduced as compared with the conventional metal mold. Also,
The handleability is greatly improved, and the safety of workers is also improved. In addition, since it has higher durability than conventional plywood forms and can be used repeatedly, it can contribute to protection of forest resources. Further, the releasability at the contact surface between the face plate and the concrete casting surface is extremely improved as compared with a plywood mold or a metal mold, and a release agent is not required. Further, a ripple effect that cleaning after removing the mold is very easy can be obtained. Thus, simplification of the process and cost reduction due to the elimination of a stripping agent can be achieved.

Further, since the face plate is so transparent that the condition of the concrete can be checked, the work of driving and compacting the concrete, which has conventionally relied on the intuition and experience of the worker, can be performed with the naked eye. Can be confirmed from the outside, and defects in the concrete structure can be prevented in advance. This leads to a reduction in rework and ultimately to a reduction in the cost of the concrete structure.

[0018]

FIG. 1 is a top view showing a mold according to an embodiment of the present invention. 2 and 3 are a front view and a side view, respectively, of the embodiment of FIG. FIG. 4 is a sectional view taken along line AA shown in FIG. FIG. 5 shows an example of a conventional plywood formwork or stampable sheet formwork. FIG. 6 shows an example of a conventional metal mold.

Referring to FIGS. 1 to 4, outer longitudinal ribs 1 are provided in parallel at both longitudinal outer edges of the face plate 3, and two inner longitudinal ribs 2 are arranged inside the outer ribs. Is provided. In the direction orthogonal to the longitudinal direction of the face plate 3,
Are provided. Forming holes 7 are formed in the outer vertical ribs 1 and the horizontal ribs 6 located at both ends, which are used when the form is combined with a fastening material such as a bolt, a nut or a clip. . As shown in FIG.
And a lower flange 5 are provided. Providing such an upper flange 4 and a lower flange 5 is an effective means for increasing the bending rigidity in the longitudinal direction of the formwork.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto. A metal mold having a size of 300 mm in width, 1500 mm in length, and 55 mm in height is commonly used.

Example 1 Acrylonitrile / styrene copolymer resin (AS) was used as a thermoplastic resin having high transparency, and pulverization was performed to improve the impregnation property of glass fibers as reinforcing fibers.
As a reinforcing fiber, a chopped strand mat made of glass fiber having a cut length of 50 mm was used, and the number of laminated layers was determined so that the volume content of the glass fiber became 30%. The crushed resin and the chopped strand mat are alternately set in a flat mold heated to a molding temperature in advance, heated and pressed, then cooled and solidified to have a thickness of 3.8.
mm for press molding reinforced with glass fiber mat
Wood was obtained.

This sheet material is heated in an infrared heating furnace to a temperature 20 ° C. higher than the melting temperature of the resin, and is immediately charged into a mold and stamped to obtain a sheet having a width of 300 mm.
A face plate having a length of 1500 mm and a thickness of 3 mm was obtained. A test piece was cut out from the face plate, and the total light transmittance and the haze value were measured using a haze meter (Model TC-H, manufactured by Tokyo Denshoku Co., Ltd.).
IIIDP type). As a result, values such as a total light transmittance of 70% and a haze value of 68% were obtained.

Example 2 A mixed fiber was produced using 5175 denier continuous glass fiber as the reinforcing fiber and 2740 denier polyester continuous fiber as the thermoplastic resin fiber. The above-described mixed yarn is wound around a metal frame and subjected to compression molding by press using a mold having both ends opened under a predetermined tension, and has a width of 500 mm, a length of 1500 mm, and a thickness of 6 mm.
And two types of unidirectionally strengthened flat plates having a thickness of 3 mm. Outer and inner vertical ribs from a 6mm thick flat plate,
The upper and lower flanges of the inner vertical rib were each cut. Further, a horizontal rib was cut from a flat plate having a thickness of 3 mm.
At the time of cutting, the reinforcing direction of the reinforcing fibers was set to the longitudinal direction of each member. These members were assembled by bonding with an epoxy adhesive to produce a rib structure.

The produced rib structure and the face plate produced in Example 1 were assembled by bonding with an epoxy adhesive.
A mold having a width of 300 mm, a length of 1500 mm, and a height of 55 mm as shown in FIG. 1 was produced.

Comparative Example 1 An ordinary polypropylene resin (PP) was used as a thermoplastic resin having no transparency. In the same manner as in Example 1,
First, a sheet material for press molding having a thickness of 3.8 mm was obtained from a chopped strand mat made of glass fiber having a cut length of 50 mm so that the volume content was 30%. Next, 300 mm wide and 150 mm long by stamping.
A face plate having a thickness of 0 mm and a thickness of 3 mm was obtained. A test piece was cut out from the face plate, and the total light transmittance and the haze value were measured. As a result, the total light transmittance was 38% and the haze value was 91%.

Further, the above-mentioned face plate was attached to a rib structure produced in the same manner as in Example 2 by bonding with an epoxy adhesive, and the width was 300 mm and the length was 1500 as shown in FIG.
mm, a mold frame having a height of 55 mm was produced.

COMPARATIVE EXAMPLE 2 Conventionally, a width of 300 mm, a length of 1500 mm,
A commercially available metal (iron) form having a height of 55 mm and a plywood form obtained by driving a pier to a control panel having a width of 900 mm, a length of 1800 mm and a thickness of 12 mm were prepared.

Example 3 A concrete casting test was performed using the molds prepared in Example 2 and Comparative Example 1 and the conventional mold prepared in Comparative Example 2. The formwork was kept at an interval of 30 cm by a separator, and thick ends were installed at predetermined positions on the side opposite to the casting surface. The concrete is usually Portland cement,
A 4-week strength 240 kgf / cm ² , aggregate size 40 mm, slump 8 cm specification was used.

When the concrete was cast, the mold of Example 2 according to the present invention could be observed as if the concrete had been cast by hand through the face plate. Further, it was possible to see the state of the voids that caused avatars after the concrete was cured, and it was possible to take measures with a vibrator. On the other hand, the mold of Comparative Example 1 could confirm the presence or absence of concrete, but could not confirm the state of the voids and the state of the concrete surface such as the seam at all. . In the conventional mold prepared in Comparative Example 2,
Needless to say, the presence or absence of concrete could not be confirmed.

When the mold was removed from the mold on the third day after casting the concrete, the molds of Example 2 and Comparative Example 1 used a release agent because the face plate was made of glass fiber reinforced thermoplastic resin. Although it was not applied, the mold could be removed very easily without using a hammer or the like. In addition, there was almost no adhesion of concrete on the face plate, and cleaning by wiping with a wet cloth was sufficient, and there was no necessity for ordinary cleaning work. On the other hand, although the conventional mold of Comparative Example 2 was coated with a release agent, it could not be removed without using a hammer or a bar when removing the mold.

Observation of the finished concrete structure showed that the mold of Example 2 according to the present invention had no surface undulation and had less avatars compared to the conventional concrete structure. A very good concrete structure was obtained. On the other hand, in the molds of Comparative Example 1 and Comparative Example 2 in which it was impossible to confirm the state of the concrete, a large number of avatars were observed on the surface of the completed concrete structure. In the case of the plywood formwork of Comparative Example 2, grain transfer was also confirmed on the surface of the concrete structure. Further, when a repeated casting test was carried out, rust was generated on the face plate of the metal (iron) formwork of Comparative Example 2, and the rust phenomenon was observed on the surface of the concrete structure.

[0032]

[Table 1] Table 1 shows the results of comparison of typical evaluation items of the formwork, including the results of the concrete casting test of Example 3. As is clear from the comparison in Table 1, it can be seen that the mold of Example 2 according to the present invention is superior in many respects to other molds.

[Brief description of the drawings]

FIG. 1 is a top view showing a mold according to an embodiment of the present invention.

FIG. 2 is a front view showing a mold according to an embodiment of the present invention.

FIG. 3 is a side view showing a mold of one embodiment according to the present invention.

FIG. 4 is a sectional view taken along line AA shown in FIG.

FIG. 5 is an example of a conventional plywood formwork or stampable sheet formwork.

FIG. 6 is an example of a conventional metal mold.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Outer longitudinal rib 2 Inner longitudinal rib 3 Face plate 4 Upper flange 5 Lower flange 6 Horizontal rib 7 Formwork coupling hole 8 Conventional plywood formwork or stampable sheet formwork 9 Girder 10 Nail

Claims (1)

(57) [Claims] 1. A concrete casting formwork comprising a face plate and reinforcing ribs provided at least along the longitudinal direction of the face plate, wherein the reinforcing ribs are made of fiber-reinforced thermoplastic. The face plate is made of resin ,
Contains 10% or more glass fiber of 10mm or more
Is formed from a glass fiber reinforced thermoplastic resin, the total light transmittance of said surface plate is more than 50% and haze is 80%
A concrete casting formwork characterized by the following.