JP6667805B2 - Concrete formwork - Google Patents

Description

  The present invention relates to a concrete formwork.

It is known that underwater curing is suitable for increasing the strength, denseness, crack resistance and durability of concrete.
Therefore, when curing concrete, a curing method aimed at preventing drying and creating an environment similar to underwater curing is employed.
As such a curing method, for example, there is a method of spraying water on the surface of concrete after demolding. However, sprinkling curing can create an environment similar to underwater curing on horizontal surfaces such as the top surface of concrete, but it takes time to maintain water uniformly and evenly on vertical surfaces and slopes such as side surfaces. .

Therefore, the present applicant has developed a concrete form having water retention as shown in Patent Document 1, for example, and has come to practical use.
The concrete formwork described in Patent Literature 1 has a weir plate provided with a plurality of core members and face members respectively laminated on both surfaces of the core member. A plurality of through holes are formed in the surface material on the concrete casting surface side. And by storing the curing water in the gap between the core materials, the curing water is directly supplied to the surface of the concrete from the through hole. According to the concrete formwork of Patent Document 1, an environment close to underwater curing can be created.

JP 2013-238044 A

When the concrete form described in Patent Literature 1 is applied to a concrete structure having a large difference in the height of the curing range, the water pressure at the lower portion of the dam is higher than that at the upper portion, so that the supply amount of the curing water is not uniform, There was a possibility that unevenness would occur in the wet state.
Further, when water cannot be supplied from the upper end of the concrete form due to the situation at the site, the shape of the concrete structure, or the like, there is a possibility that the curing water may be insufficient at the upper part of the concrete form.

  From such a viewpoint, an object of the present invention is to propose a concrete formwork capable of uniformly supplying curing water to the surface of concrete.

A concrete formwork of the present invention for solving the above problems includes a water supply layer covering a surface of concrete, a weir formed along a back surface of the water supply layer, and a water supply pipe for supplying curing water. And the water supply layer is made of a sheet material having water permeability, and the weir plate is divided into an upper part and other parts, and at least the inside of the upper part is hollow and the other parts are separated from each other. The space is partitioned, and the surface of the upper part on the side of the water supply layer is provided with a means for leaching curing water, and the water injection pipe is connected to a side surface of the upper part, and the water injection pipe is curing water supplied to the upper portion through is penetrated into the water supply layer through the leaching means, and an overall spread Rukoto wherein in the feed water layer.
As the leaching means, for example, a plurality of through holes may be formed in the weir.

According to such a concrete formwork, the curing water is stored inside the upper portion of the weir board, and the curing water leached from the upper portion penetrates into the water supply layer, so that it can be uniformly supplied to the entire surface of the concrete. it can.
Further, since the storage of the curing water is restricted to the upper part, even if there is a large difference in height in the curing range, there is no large difference in water pressure between the upper part and the lower part of the curing range.

A core material obtained by thermally fusing the two thermoplastic resin sheets on each of which the plurality of hollow convex portions are formed with the hollow convex portions facing each other; and If it is provided with the laminated face materials, it is possible to secure the strength as a weir board while securing the water storage.
The height of the upper portion is preferably 100 cm or less, more preferably in the range of 20 cm to 40 cm.

  ADVANTAGE OF THE INVENTION According to the concrete formwork of this invention, since curing water can be supplied uniformly to the surface of concrete, it becomes possible to manufacture a high quality concrete member or concrete structure.

It is sectional drawing which shows the installation situation of the concrete formwork which concerns on embodiment of this invention. It is sectional drawing which shows the dam of the concrete formwork shown in FIG. (A) And (b) is sectional drawing which shows the use situation of a concrete formwork.

The concrete formwork 1 of the present embodiment is a formwork used at the time of placing concrete, and as shown in FIG. 1, a water supply layer 2 and a weir board 3 are laminated.
The water supply layer 2 is in contact with the surface of the concrete, absorbs excess water (including breathing water) generated after the concrete is poured, and supplies water (curing water) to the surface of the concrete during curing of the concrete. .

  The water supply layer 2 of the present embodiment is a nonwoven fabric disposed so as to cover the surface of concrete. The material constituting the water supply layer 2 is not limited as long as it is a sheet material having water permeability, and may be, for example, a woven fabric.

The weir plate 3 is formed on the back surface of the water supply layer 2 (the surface opposite to the concrete).
The weir 3 is divided into an upper part 4 and a lower part 5. Note that the number of divisions of the weir plate 3 is not limited.
The upper part 4 of the present embodiment is formed to have a height of 30 cm. Although the height of the upper portion 4 is not limited, it is desirably 100 cm or less, preferably in the range of 20 cm to 40 cm. If the height of the upper part 4 is too large, the head difference between the upper part and the lower part of the upper part 4 will increase, and the supply amount of the curing water will be different. If the height of the upper portion 4 exceeds 100 cm, the dam plate 3 (the upper portion 4) may be damaged by water pressure. On the other hand, if the height of the upper portion 4 is too small, the curing water supplied to the surface of the concrete member cannot be sufficiently stored.

The upper part 4 and the lower part 5 are hollow inside, and are partitioned between the upper part 4 and the lower part 5. That is, fluid is not allowed to flow from the upper portion 4 to the lower portion 5.
Note that the weir plate 3 only needs to be hollow at least inside the upper part 4, and the lower part 5 does not necessarily have to be hollow.

  As shown in FIG. 2, the weir plate 3 of the present embodiment includes a core member 30 and face members 33, 33 laminated on both surfaces of the core member 30, respectively. The core material 30 is formed by heat-sealing two thermoplastic resin sheets 31, 31 each having a plurality of hollow convex portions 32, 32,... Formed with the hollow convex portions 32 facing each other. .

  The dam member 3 of the present embodiment is constituted by a core member 30 having strength and rigidity that does not deform under the pressure (side pressure) of the poured concrete. A core material 30 having a bending elastic gradient of 1500 N / cm or more when a three-point bending test is performed using a test piece having a width of 50 mm x a length of 150 mm, a distance between supporting points of 100 mm, and a bending speed of 20 mm / min. It is preferred to use If the bending elasticity gradient is 1500 N / cm or less, the mold may be bent at the time of installation.

The hollow convex portions 32, 32,... Of the thermoplastic resin sheets 31, 31 are frustoconical and have the same dimensions. Are regularly and staggeredly arranged on one surface of the thermoplastic resin sheet 31, and a continuous internal space 34 is provided inside the core member 30. Are formed.
The shape of the hollow convex portion 32 is not limited to a truncated cone, and may be, for example, a truncated pyramid or a column. Further, the size and arrangement of the hollow projections 32 are not limited.

  Further, the material constituting the thermoplastic resin sheet 31 is not limited, but a polypropylene-based resin such as homopolypropylene, random polypropylene, block-shaped polypropylene, and the like, may be used in terms of productivity, cost, physical properties, low-temperature resistance, and heat resistance. It is preferable from the viewpoint of the balance with the characteristics such as.

  The face materials 33, 33 laminated on both sides of the core material 30 are made of a plate material or a sheet (thermoplastic resin sheet) made of a thermoplastic resin. The material of the face material 33 is not limited, but it is compatible with the core material 30 and can be heat-fused. For example, a polypropylene-based resin such as homopolypropylene, random polypropylene, and block-shaped polypropylene is preferable from the viewpoint of excellent heat resistance.

  The side end surface, the upper end surface, and the lower end surface of the weir plate 3 are sealed (sealed) with a sealant. In the present embodiment, the sealing is performed by heat-sealing the sealing material (sealing material). However, the sealing method is not limited, and the sealing may be performed using a sealing material, for example. In addition, although the material which comprises a sealing material is not limited, In this embodiment, it consists of the same material as the face material 33.

A plurality of through holes (leaching means) 35, 35,... Are formed on the surface (surface) on the water supply layer side of the weir plate 3 so that water (curing water, breathing water, etc.) can flow in and out. Have been. The through holes 35 are formed in the face material 33 and the core material 30, and some of the through holes 35 reach the internal space 34.
Therefore, when water flows through the internal space 34 of the upper part 4, the water flows out from the through hole 35 and soaks into the water supply layer 2. The water that has permeated the water supply layer 2 is supplied to the concrete surface.

The size of the through hole 35 is not limited, but is preferably 1 mm or more in diameter so as not to be clogged with mortar or fine aggregate.
Further, the arrangement of the through holes 35 is not limited, but in the present embodiment, the distance between the through holes 35 (the distance between the adjacent through holes 35) is 10 mm or more.
Further, the method of forming the through holes 35 is not limited, but in the present embodiment, a plate material on which a large number of needle-like members are planted is pressed from one surface side of the weir plate 3 to pierce the needle-like members. It is formed by inserting.

Next, a method of constructing a concrete member using the concrete formwork 1 will be described.
The method for constructing a concrete member includes a formwork assembling step, a concrete placing step, a curing step, and a demolding step.

The formwork assembling step is a step of assembling the concrete formwork 1 at a predetermined position.
In the present embodiment, as shown in FIG. 1, a pair of concrete forms 1 and 1 are arranged at positions where the construction of the concrete member is planned so as to face each other with a gap corresponding to the thickness of the concrete member ( FIG. 1 shows only one concrete form 1).
The concrete forms 1 and 1 are arranged such that the respective water supply layers 2 face each other.
Along with the arrangement of the concrete form 1, necessary reinforcing bars (not shown) are arranged while appropriately arranging reinforcing bar spacers. The reinforcing bars may be arranged as needed.

The concrete placing step is a step of placing concrete in a gap between the concrete forms 1.
The surplus water Ws including the breathing water generated after the concrete is poured flows out from the through holes 35, 35,... To the internal space 34 of the concrete form 1 as shown in FIG. Excess water Ws that has flowed into the internal space 34 may be drained as appropriate. As a means for draining surplus water, for example, the surplus water may be drained from a drain port (not shown) formed on the surface of the weir plate 3 opposite to the water supply layer.

The curing step is a step of curing until the cast concrete C exhibits a predetermined strength.
The curing step, as shown in FIG. 3 (b), supplies the curing water W ₀ in the inner space of the upper portion 4 (water holding section), perform the curing of pouring concrete in an environment similar to water curing. Supply of curing water W ₀ in the internal space of the upper portion 4 supplies the water injection tube 6 connected to the side surface of the upper portion 4 of the sheathing board 3.
In the present embodiment, a water injection pipe 6 is connected to a water tank 7 disposed at a position higher than the upper part 4, and the curing water is supplied to the upper part 4 by flowing down naturally.
The supply method of curing water W ₀ is not limited, for example, it may be pumped by a pump or the like.

Curing water W ₀ supplied to the upper portion 4, the through-holes 35, 35, after having penetrated into water layer 2 by inserting the ..., spread entirely within the water layer 2 by a capillary phenomenon or gravity flow, hitting It is supplied evenly to the entire surface of the concrete. As the curing water W ₀ to be supplied to the upper part 4, it may be used water, but in addition to water, use of calcium hydroxide (saturated) solution, surface impregnating agent, the permeability rust agent This may improve the durability by forming the hardened body of the cast concrete more densely. The use of these liquids results in the supply of additional active ingredients from the outside, which promotes the hydration reaction and increases the amount of hydration products, thus providing continuous voids that can easily serve as a path for the movement of substances. Can be more effectively blocked, and further, in addition to the curing effect, additional functions such as a water-repellent effect and a rust-preventive effect can be imparted.

In addition, when applied to mass concrete, it may be used hot water as curing water W _0. If the curing water W ₀ in the hot water, it is possible to reduce the temperature difference between the concrete inside and outside due to heat generation of the cement. Further, if of stripping concrete formwork 1 even after discharging the curing water W ₀ from dams 3, since the heat insulating layer due to air is formed, it is possible to kept the concrete. Thereby, cracks caused by temperature stress can be prevented.

  The demolding step is a step of demolding the concrete form 1 and is performed after a predetermined strength is developed in the cast concrete.

As described above, according to the concrete form 1 of the present embodiment, it possible to realize in situ cured in water, thereby preventing the escape of curing water W ₀ in concrete curing, actively curing water W ₀ By supplying the concrete, the quality of the concrete can be improved. The through-holes 35, 35, by eliminating the excess water W _S and bubbles in the surface layer portion of the concrete from ..., as well as improving the appearance of the surface of the concrete element, thereby improving the strength and durability of the surface of the concrete member .

Since curing water W ₀ that is stored in the upper portion 4 of the sheathing board 3 is supplied to the water supply layer 2, it is possible to form the environment close to the water curing. Therefore, hydration of the concrete surface is promoted, and it becomes possible to form a denser concrete hardened body.

Since the supplies curing water W ₀ only in the upper part 4 is curing water W ₀ on the entire surface of the concrete through the water supply layer 2 is supplied, it is possible to totally uniform curing.
Further, since the water storage of the curing water W ₀ are limited only to the upper part 4, is not a large difference in water pressure occurs between the upper part and the lower part of even curing range as a large height difference curing range were present .

Supply of curing water W ₀ in the upward portion 4 in order to perform the water injection tube 6 which is attached to the side of the upper part, for example, that there is a ceiling or the like, supplying the curing water W ₀ from the upper end of the concrete formwork 1 even if it is not possible, it is possible to supply the curing water W ₀ onto portions 4.
In order to supply the curing water W ₀ by gravity flow using a water head difference, without the need for power and the like, it is economical.

Excessive water W _S containing breathing water produced concrete after casting, with incorporated into the sheathing board 3 through the water supply layer 2, for sucking bubbles water layer 2 are generated on the surface of the pouring concrete, pouring concrete Can be finished flat.
Further, since the water supply layer 2 made of a nonwoven fabric is disposed on the surface of the weir board 3, the concrete form 1 can be removed cleanly when the mold is removed. Further, the outflow of the cast concrete can be suppressed by the water supply layer 2.

  Since the internal space 34 is formed by joining the frustum-shaped hollow protrusions 32 to each other, the cross-sectional area of the internal space of the weir plate 3 is wider than that in the case where the columnar members are provided. Excellent in water permeability.

Next, the result of confirming the performance of the concrete member formed using the concrete form 1 of the present embodiment will be described.
First, the degree of rebound of a concrete member (JIS A 1155 "Method of measuring the degree of rebound of concrete") was measured (Example). As a comparative example, the degree of resilience of a concrete member formed by using a weir board in which the weir board 3 is not divided into an upper part and a lower part and the internal space is continuous from the upper part to the lower part was measured. .
Table 1 shows the measurement results.

As shown in Table 1, by using the concrete formwork 1 of this embodiment, the average value R of the resilience of the upper part 4 is 53.7, the test hammer strength F is 50.2 N / mm ² , and the lower The average value R of the resilience of the portion 5 was 54.8, and the test hammer strength F was 51.6 N / mm ² .
On the other hand, in the comparative example, the average value R of the resilience of the upper portion 4 was 51.2, the test hammer strength F was 47.0 N / mm ² , and the average value R of the resilience of the lower portion 5 was 55.5. Hammer strength F was 52.4 N / mm ² .
Therefore, in the comparative example, a difference occurs in the degree of rebound between the upper part and the lower part of the concrete member. On the other hand, when the concrete form 1 of the present embodiment is used, the upper part of the concrete member is There was no difference in the degree of restitution between the lower portion and the lower portion, indicating that uniform curing was possible.

Next, an air permeability test of the concrete was performed, and an air permeability coefficient (KT value) was measured. Table 2 shows the test results.
Three measurement positions were set for the upper part and the lower part of the concrete member.

The concrete member using the concrete form 1 of the present embodiment had a KT value of 0.0018 to 0.0110 × 10 ⁻¹⁶ × mm ² , whereas the comparative example had a KT value of 0.0028 to 0.047 ×. 10 ⁻¹⁶ × mm ² .
Therefore, the use of the concrete form 1 of the present embodiment resulted in a decrease in air permeability. Further, the concrete form 1 of the present embodiment has a result in which the difference between the maximum value and the minimum value of the KT value is smaller than that of the comparative example.
Therefore, according to the concrete form 1 of the present embodiment, it is possible to form a dense and uniform quality concrete structure.

The embodiment according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described respective components can be appropriately changed without departing from the spirit of the present invention.
For example, concrete members manufactured by the concrete form 1 are not limited, and include, for example, all concrete members such as box girders, wall members, retaining walls, culvert wall surfaces, floor slab concrete, and tunnel lining concrete. Applicable.

In the above embodiment, the concrete form 1 is used for cast-in-place concrete. However, the concrete form 1 may be used when forming a precast member in a factory or the like.
In the above-described embodiment, the case where the upper end surface of the weir plate 3 is sealed is described. However, the upper end surface of the weir plate need not necessarily be sealed. The supply of the curing water to the upper part 4 may be performed from the upper end of the upper part 4 and is not limited.
The surplus water Ws drained from the internal space 34 may be used for curing water.

DESCRIPTION OF SYMBOLS 1 Concrete formwork 2 Water supply layer 3 Weir board 30 Core material 31 Thermoplastic resin sheet 32 Hollow convex part 33 Face material 34 Internal space 4 Upper part 5 Lower part (other parts)

Claims (2)

A water supply layer covering the concrete surface,
A weir plate formed along the back surface of the water supply layer,
A water supply pipe for supplying curing water, and a concrete formwork comprising:
The water supply layer is made of a sheet material having water permeability,
The weir is divided into an upper part and other parts,
At least the inside of the upper part is hollow and partitioned from the other parts, and the surface of the upper part on the water supply layer side is provided with a leaching means for curing water ,
The water injection pipe is connected to a side surface of the upper portion,
The water injection pipe curing water supplied to the upper portion via the said permeates the water layer through the leaching means, the overall spread Rukoto wherein in the feed water layer, the concrete formwork . A core material obtained by thermally fusing the two thermoplastic resin sheets on each of which the plurality of hollow convex portions are formed with the hollow convex portions facing each other;
The concrete formwork according to claim 1, comprising: a face material laminated on both sides of the core material.

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