JPH03262871A - Highly permeable formwork for casting concrete - Google Patents

Abstract

PURPOSE:To form a fine concrete surface by fitting a textile sheet, impregnated with highly permeable resin, peelably at the concrete cast-in side face of a synthetic resin plate with numerous dehydrating pore parts formed at the whole surface thereof. CONSTITUTION:A textile sheet 3, impregnated with highly permeable resin, having numerous minute pores 4, is peelably stuck to the concrete cast-in side face 1a of a synthetic resin plate 1 provided with numerous dehydrating pore parts 2 on the whole surface thereof to form a formwork. When concrete is cast in this formwork, the moisture in the concrete is drained outside the formwork through the minute pores 4 of the textile sheet 3 and the hole parts 2 of the synthetic resin plate 1.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention can remove most of the moisture generated from concrete during concrete placement in a short time, and simultaneously improve the surface condition and curing condition after hardening. This relates to formwork for concrete pouring.

<Prior Art> As is well known, excessive water is added to concrete poured when constructing a concrete structure in order to ensure workability. This excess water is removed by compacting the concrete after it is placed.

However, the water separated during compaction collects on the formwork surface with air bubbles, which causes so-called avatars on the hardened concrete surface.

This not only impairs the aesthetic appearance of the concrete surface, but also causes cracks due to cross-sectional defects.

In addition, excess water that collects at the interface between the poured concrete and the formwork increases the water-to-cement ratio of the concrete in this area, reducing the durability of concrete after hardening and accelerating deterioration due to salt damage. .

The above-mentioned defects in poured concrete are due to the conventional use of formwork made of wooden plywood (plywood) or steel frames when pouring concrete.

With the aim of eliminating such defects and actively draining the moisture present on the concrete pouring surface to the outside,
In recent years, molds with a water permeable layer on the surface of the formwork (Japanese Patent Laid-Open No. 1983-
No. 11766), a formwork consisting of a weir plate with small holes for dewatering, thick timbers to maintain the shape of this weir plate, and shoring to increase the rigidity of this thick timber (Japanese Patent Laid-Open No. 62 -1
No. 60366), a formwork with a water-permeable and breathable release material attached to one side of a rigid urethane foam plate (Japanese Patent Laid-open No. 60366),
3-55264), and a formwork in which a water-conducting buffer sheet and a water-permeable filter sheet are laminated on the concrete casting side of the formwork (Japanese Patent Laid-Open No. 1-310061) have been proposed.

<Problems to be Solved by the Invention> However, although it is possible to remove and eliminate excess moisture generated from concrete during concrete pouring using any of these formworks, it is possible to remove and eliminate excess moisture generated from concrete during concrete pouring, but after the concrete is poured and hardened and the formwork is removed. There were problems such as the curing of concrete requiring a great deal of labor and the appearance of blisters remaining on the concrete surface.

Means for Solving the Problems> This invention was made as a result of studies to solve the above problems, and it can be easily peeled off even when the concrete is completely hardened to maintain its aesthetic appearance, and it can also be used to cure the concrete. The present invention provides a formwork in which a highly water-permeable special sheet is attached to a synthetic resin plate with a large number of holes formed therein so that curing can be carried out in a wet state while securing the necessary moisture.

That is, the formwork of the present invention is a synthetic resin plate with a large number of dewatering holes formed on its entire surface, and a fabric sheet impregnated with a highly water-permeable resin is removably attached to the concrete-casting side surface of the synthetic resin plate.

Effect> In this invention, a fabric sheet containing a highly water-permeable resin is removably attached to the concrete pouring side of a synthetic resin plate with a large number of small holes for dewatering formed on the entire surface.
Among the poured concrete, the water in the concrete near the fabric sheet impregnated with highly permeable resin flows out from the fabric sheet, and the synthetic resin board to which this fabric sheet is attached is also covered in large numbers. Since the dewatering holes are formed, the moisture flowing out to the outside of the fabric sheet is discharged from the synthetic resin plate to the outside through the dehydrating holes.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a formwork according to the present invention, and FIG. 2 shows a state in which concrete is poured using the formwork according to the present invention.

In the figure, l is a synthetic resin plate, and a large number of holes 2 for dehydration are formed on the entire surface. 5 is the ridgepole.

Further, numeral 3 is a fabric sheet impregnated with a highly water-permeable resin, and has a large number of micropores 4 on its entire surface, making it breathable.

The formwork of the present invention has one side of the above synthetic resin plate l, that is,
A fabric sheet 3 impregnated with a highly water-permeable resin is removably attached to the concrete pouring side 1a, and when concrete is poured using this formwork as shown in Figure 2, moisture in the concrete is removed. Dehydration is done using a breathable fabric sheet 3
Since the pouring is carried out at an appropriate speed through the numerous holes 2 of the synthetic resin plate 1, breathing water and air bubbles in the concrete are quickly discharged outside the formwork. Water and water avatar are reduced to almost nothing, making it possible to form a dense concrete structure. Moreover, since the strength of the surface concrete is developed faster, the initial curing effect is greater, and strong, dense, yet beautiful concrete structures can be realized in a shorter construction period than before.

In addition to increasing surface strength, it is also highly effective in slowing down the carbonation rate, reducing and suppressing salt permeability, and can also strengthen salt damage resistance.

The breathable fabric sheet with a large number of micropores used in this invention is made by impregnating a fabric made of highly functional hydrophobic bundles into a multilayer structure with a highly water-permeable resin.
A thick sheet with a high density less than φ and a smooth surface is used.

The permeability of less than 1 cc/cm''/see is effective in blocking the outflow of activated cement particles and ventilating and draining air holes and excess water.

At the final stage of dehydration, the final water permeation effect is greatly enhanced by the capillarity and diffusion phenomena of the fibers.

In order to absorb and fix calcium ions (Ca”°) in breathing water and suppress the production of calcium carbonate (CaCOs), which is the main component of laitance, this is done by fixing C1° ions by the C00-groups of the water-permeable resin. It is based on

The synthetic resin used in this invention with holes for dehydration formed on its entire surface may have holes in any shape, such as the rhombus shown in Fig. 3, the square shown in Fig. 4, the triangle shown in Fig. 5, or the hexagonal shape shown in Fig. 6. There is no problem even if the holes are formed on both sides at different levels, as shown in FIG. 7 (A) as a plan view and as shown in FIG. 7 (B) as a side view. It may be of.

Incidentally, among the synthetic resin plate 1 and the fabric sheet 2 constituting the formwork of the present invention, the synthetic resin plate l requires crosspieces 5 at required intervals on the outside as shown in FIG. 1 or 2. However, it is preferable that the crosspieces 5 are integrally molded when manufacturing the synthetic resin plate 1 that has many holes formed on the entire surface, but after the synthetic resin plate 1 is molded, synthetic resin crosspieces 5 are formed in required parts.
You may also install it.

Looking at the avatar rate and amount of water removed when concrete is poured using the formwork of this invention and conventional plywood formwork such as plywood, it is found that the large amount of water removed means that the surface strength of concrete is proportionally reduced. It means to increase the number of people.

Such an increase in initial strength has advantages such as early demolding, improved lateral pressure resistance, savings in temporary materials, and increased economic efficiency, as well as improved freezing resistance.

Furthermore, the surface strength of concrete cast using the formwork of the present invention was found to be 1.3 to 1.8 times higher than that of plywood 3 and 28 days after casting.

<Effects of the Invention> As explained above, if the formwork of the present invention is used, activated cement particles will not pass through, and bubble permeability will be perfected to allow dewatering and water permeation to occur at an appropriate speed, resulting in concrete pouring. It is possible to reliably prevent the formation of air bubbles, blisters, and fine irregularities on the concrete surface, resulting in a beautiful concrete surface.

Therefore, in the summer, it has an insulating effect and suppresses moisture evaporation, increasing the curing effect and preventing the occurrence of cracks on the surface of poured concrete in areas with large temperature differences between day and night, and rain and shine, such as in mountainous areas. .

In addition, excess water and air bubbles in poured concrete are removed through the sheet, so the hardening speed of the concrete in contact with the sheet increases, initial strength increases, and early demolding of the formwork becomes possible. This also has the effect of increasing the number of times the frame is used.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the configuration of the formwork of the present invention, Fig. 2 is a perspective view showing concrete placement using the formwork of the invention, and Figs. 3 to 6 are the formwork of the invention. FIG. 7(A) is a front view showing the shape of the hole in a synthetic resin plate having holes on its entire surface, and FIG. 7(B) is a front view showing another example of the shape of the hole in the synthetic resin plate. ) is its side view. 1...Synthetic resin board

Claims (1)

[Claims] A formwork with excellent water permeability for pouring concrete, which is made by removably attaching a fabric sheet impregnated with a highly water-permeable resin to the concrete pouring side of a synthetic resin board with many holes for dewatering formed on the entire surface. .