JP2021098996A - Concrete curing sheet and usage method thereof - Google Patents

Abstract

To provide a concrete curing sheet capable of securely curing concrete placed and achieving high curing effect.SOLUTION: A concrete curing sheet 10 is disposed on an inner face 1a of a formwork for concrete placement 1. The curing sheet 10 comprises a permeable layer 13 facing a concrete placement space 1c, a water shielding layer 13 facing the inner face 1a, and a drainage layer 12 letting water through in-plane direction, disposed between the permeable layer 11 and the water shielding layer 13. During curing period, water is supplied to a sprayed water receiving part 10d formed at an end of the curing sheet 10 such that water passes through the drainage layer 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to a curing sheet used for curing cast concrete and a method of using the same.

Concrete needs to be cured so that it remains moist for a period of time after casting. When dried, the hydration reaction of cement does not proceed and quality cannot be ensured. Therefore, it is known that a curing sheet containing a water-retaining layer is stretched on the concrete being cured (see Patent Document 1).

JP-A-2018-071283

The curing sheet of the above-mentioned patent document wet-cures concrete by including a water-retaining layer. However, if the amount of water retained in the water-retaining layer is insufficient, the moist state cannot be maintained and the curing effect is reduced.
In view of such circumstances, an object of the present invention is to provide a concrete curing sheet capable of reliably curing the cast concrete and a high curing effect, and a method of using the same.

In order to solve the above problems, the present invention is a concrete curing sheet provided on an inner surface that defines a concrete casting space in a concrete casting formwork.
A permeable layer that faces the concrete placement space and allows water to pass in the thickness direction,
The impermeable impermeable layer facing the inner surface and
A drainage layer provided between the permeable layer and the impermeable layer and capable of passing water in the in-plane direction,
It is characterized by being equipped with.

When the concrete curing sheet is stretched on the inner surface of the concrete casting formwork and concrete is placed in the concrete placing space, the excess water of the concrete from the time of placing to immediately after placing puts the water permeable layer in the thickness direction. It can be discharged by permeating and flowing into the drainage layer and flowing in the drainage layer in the in-plane direction. As a result, the hardening of the concrete can be promoted and the concrete is densified.
Further, during the curing after the concrete is hardened, water can be passed in the in-plane direction of the drainage layer, so that the curing can be performed at the same level as the flooded curing.

The water permeable layer is composed of a woven fabric of a thermoplastic resin or a porous sheet.
It is preferable that the drainage layer is made of a non-woven fabric.
This allows the permeable layer to reliably allow water flow in the thickness direction and block or limit water flow in the in-plane direction. In addition, water can be reliably passed in the in-plane direction of the drainage layer.
Furthermore, it is possible to prevent fibers and the like from remaining on the concrete surface after the curing sheet is peeled off.
The water permeable layer and thus the concrete curing sheet can maintain a state of close contact with the concrete placed in the concrete placing space at the time of demolding and after demolding of the formwork, and can be peeled off from the concrete after demolding. It is preferable to have.
This allows the formwork to be removed during the concrete curing process. At the time of demolding, the concrete curing sheet and the formwork are peeled off, while the concrete curing sheet can be left as it is on the concrete surface. Therefore, the concrete can be continuously cured by the concrete curing sheet even after the mold is removed. From a different point of view, the construction period can be shortened by removing the mold early. Then, at any time, preferably after the required curing period using only the concrete curing sheet is completed, the concrete curing sheet can be peeled off from the concrete and removed.

It is preferable that the end portion of the concrete curing sheet protrudes from the formwork to form a sprinkling receiving portion for receiving water sprinkling.
During the curing after the concrete is hardened, by sprinkling water on the watering receiving portion, water can flow in the in-plane direction of the drainage layer, and the curing can be performed at the same level as the flooded curing.

The water permeable layer and thus the concrete curing sheet can maintain a state of close contact with the concrete placed in the concrete placing space at the time of demolding and after demolding of the formwork, and can be peeled off from the concrete after demolding. It is preferable to have.
This allows the formwork to be removed during the concrete curing process. At the time of demolding, the concrete curing sheet and the formwork are peeled off, while the concrete curing sheet can be left as it is on the concrete surface. Therefore, the concrete can be continuously cured by the concrete curing sheet even after the mold is removed. From a different point of view, the construction period can be shortened by removing the mold early. Then, at any time, preferably after the required curing period using only the concrete curing sheet is completed, the concrete curing sheet can be peeled off from the concrete and removed.

It is preferable that the drainage layer has a thickness of 0.05 mm to 2.0 mm, a basis weight of 25 g / m ^{2 to 250 g / m 2} , and a density of 0.05 ^{g / cm 3 to} 1.0 g / cm ³ .
The thickness of the impermeable layer is preferably 1.0 mm or less.
The total thickness of the concrete curing sheet is preferably 10 mm or less.

The method of the present invention is a method of using the concrete curing sheet.
The concrete curing sheet is stretched on the inner surface that defines the concrete casting space in the concrete casting formwork.
Concrete is placed in the concrete placement space,
During the curing period after the casting, water is supplied to the sprinkler receiving portion formed at the end of the concrete curing sheet to allow water to pass through the drainage layer.
As a result, during the curing after the concrete is hardened, the curing can be performed at the same level as the flooded curing, and the quality of the concrete can be improved.

According to the present invention, the cast concrete can be reliably cured and a high curing effect can be obtained.

FIG. 1 is a cross-sectional view of a concrete placing site during curing in which concrete is placed in a formwork provided with a concrete curing sheet according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the concrete curing sheet. FIG. 3 is an enlarged cross-sectional view of the circle portion III of FIG. FIG. 4A is an enlarged plan view showing one aspect of the water permeable layer of the concrete curing sheet. FIG. 4B is an enlarged plan view showing another aspect of the water permeable layer of the concrete curing sheet. FIG. 5 is a cross-sectional view of a concrete placing site showing a curing process after demolding.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a concrete placing site. The concrete casting site is not particularly limited, and examples thereof include abutments, piers, retaining walls, tunnels, dams, buildings, and construction sites of various concrete structures. A concrete casting formwork 1 is installed at the concrete casting site. The concrete casting space 1c is defined by the inner surface 1a of the formwork 1. Concrete 2 is cast in the casting space 1c.

As shown in FIG. 1, a concrete curing sheet 10 is provided on the inner surface 1a of the formwork 1.
As shown in FIG. 2, the concrete curing sheet 10 includes a water permeable layer 11, a drainage layer 12, and an impermeable layer 13. The water permeable layer 11, the drainage layer 12, and the impermeable layer 13 are laminated in this order from the side of the concrete placing space 1c. The thickness direction of each layer 11, 12, 13 is along the stacking direction of the layers 11, 12, 13. The water permeable layer 11 and the drainage layer 12, and the drainage layer 12 and the impermeable layer 13 are joined by adhesion or fusion with an adhesive, respectively.

As shown in FIG. 3, the permeable layer 11 faces the concrete placing space 1c and is in contact with the concrete 2.
The water permeable layer 11 allows water to pass through in the thickness direction (permeation of water) and blocks the permeation of solids such as cement and aggregate. More preferably, the water permeable layer 11 blocks or limits water flow in the in-plane direction orthogonal to the thickness direction (stacking direction). That is, water can hardly flow in the in-plane direction inside the permeable layer 11.

Specifically, as shown in FIG. 4A, the water permeable layer 11 is composed of a woven fabric 20 made of thermoplastic resin fibers 21. The mesh of the woven fabric 20 is a through hole 23 that allows water to pass in the thickness direction. The size of the mesh, that is, the through hole 23 is preferably a size that allows the permeation of water and prevents the permeation of concrete particles.
Examples of the thermoplastic resin include polypropylene (PP) and polyethylene terephthalate (PET).

As shown in FIG. 4B, the water permeable layer 11 may be composed of the porous sheet 30. The perforated sheet 30 is made of a thermoplastic resin such as PP or PET, and is formed so that a through hole 33 composed of a large number of small holes penetrates in the thickness direction. The through hole 33 serves as a water passage in the thickness direction. The size of the through hole 33 is preferably a size that allows the permeation of water and prevents the permeation of concrete particles.
When the concrete 2 is cast in the casting space 1c, the water permeable layer 11 is closely joined to the concrete 2. The water permeable layer 11 and thus the curing sheet 10 can maintain a state of close contact with the concrete 2 during and after the mold 1 is demolded (FIG. 5), and can be forcibly peeled from the concrete 2 after the demolding. Is.

The impermeable layer 13 shown in FIG. 2 is made of an impermeable resin or rubber. For example, the impermeable layer 13 is made of a sheet of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or the like.
Preferably, the thickness of the impermeable layer 13 is 1.0 mm or less. If the thickness of the impermeable layer 13 exceeds 1.0 mm, it becomes costly and uneconomical.

As shown in FIG. 3, the impermeable layer 13 is in contact with the inner surface 1a of the mold 1.
An adhesive layer for being attached to the mold 1 may be provided on the surface of the impermeable layer 13 on the mold 1 side. The adhesive layer is preferably peelable from the mold 1.

As shown in FIG. 2, a drainage layer 12 is interposed between the water permeable layer 11 and the impermeable layer 13. The drainage layer 12 is made of, for example, a non-woven fabric or a sponge-like porous resin having continuous pores. The drainage layer 12 can pass water in the in-plane direction (direction orthogonal to the stacking direction of the layers 11, 12, 13). That is, the drainage layer 12 allows water to flow in the in-plane direction inside the drainage layer 12. At least the drainage layer 12 has higher in-plane water permeability than the water-permeable layer 11. The thickness of the drainage layer 12 is larger than that of the water permeable layer 11 and the impermeable layer 13.

Preferably, the drainage layer has a thickness of 0.05 mm to 2.0 mm, a basis weight of 25 g / m ^{2 to} 250 g / m ² , and a density of 0.05 g / cm ^{3 to} 1.0 g / cm ³ .
When the thickness of the drainage layer 12 is less than 0.05 mm, the water flow space (thickness) is narrow and the drainage capacity is insufficient. If the thickness of the drainage layer 12 exceeds 2.0 m, it becomes costly and uneconomical.
If the basis weight of the drainage layer 12 ^{is less than 25 g / m 2} , it will be crushed by the concrete placing pressure, and a uniform drainage capacity cannot be reproduced. If the basis weight of the drainage layer 12 ^{exceeds 250 g / m 2} , it becomes costly and uneconomical.
If the density of the drainage layer 12 ^{is less than 0.05 g / cm 3} , the drainage layer 12 is crushed by the concrete placing pressure, and a uniform drainage capacity cannot be reproduced. If the density of the drainage layer 12 ^{exceeds 1.0 g / cm 3} , roll molding cannot be performed and the productivity is inferior.

Preferably, the total thickness of the concrete curing sheet 10 is 10 mm or less. If the total thickness exceeds 10 mm, it has a great influence on the shape and dimensions of the concrete structure.

As shown in FIGS. 1 and 3, for example, the upper end portion of the curing sheet 10 installed in the mold 1 protrudes from the mold 1 and constitutes the sprinkler receiving portion 10d. Preferably, the sprinkler receiving portion 10d is bent and covered with the upper end surface of the mold 1, and is fixed to the mold 1 with fasteners (not shown) such as staples and nails. The water permeable layer 11 in the sprinkler receiving portion 10d constitutes the outer surface (upper surface) of the sprinkling receiving portion 10d. The impermeable layer 13 in the sprinkler receiving portion 10d faces the upper end surface of the mold 1.
Further, as shown in FIG. 1, the lower end portion of the curing sheet 10 is bent along the bottom surface of the mold 1 to form the discharge path 10e. The end face of the discharge path 10e faces the outside of the mold 1.

The concrete curing sheet 10 is used as follows.
The curing sheet 10 is attached to the inner surface 1a of the mold 1 to assemble the mold 1.
The upper end of the curing sheet 10 is a watering receiving portion 10d. The lower end of the curing sheet 10 is a discharge path 10e.

Next, the concrete 2 is placed in the space 1c in the formwork 1. The amount of water in the concrete 2 at the time of casting should be larger than the amount required for hardening. As a result, the fluidity of the concrete 2 can be increased and the casting workability can be improved.
The water permeable layer 11 comes into contact with the concrete 2 in the space 1c. Excess water exceeding the required amount seeps out from the concrete 2 into the water permeable layer 11, permeates the water permeable layer 11 in the thickness direction, and flows into the drainage layer 12. Then, it flows in the drainage layer 12 along the in-plane direction and is discharged to the outside from the discharge path 10e. As a result, the hardening of the concrete 2 can be promoted, and the concrete is densified and the quality is improved by lowering the water-cement ratio W / C.
While the water permeable layer 11 allows water to flow in the thickness direction, the water flow in the in-plane direction is blocked or restricted so that excess water can be uniformly discharged from the entire surface (contact surface of the curing sheet) of the concrete 2. Can be discharged.
Solid components such as cement and aggregate in the concrete 2 cannot penetrate the water permeable layer 11 and can prevent the outflow.

After the concrete 2 is hardened, it is cured for a certain period of time to ensure quality.
As shown in FIG. 1, water is continuously or appropriately sprinkled on the sprinkler receiving portion 10d during the curing. For example, the watering nozzle 3 is installed above the concrete casting formwork 1. Water w is supplied from the watering nozzle 3 to the watering receiving portion 10d.
Watering may be continued, intermittently or irregularly.
As shown by the thick line with an arrow in FIG. 3, the water w from the watering nozzle 3 propagates in the drainage layer 12 from the watering receiving portion 10d in the in-plane direction, so that the water permeable layer spreads over a wide area of the curing sheet 10. It is supplied to the concrete 2 via 11. As a result, the concrete 2 can be surely kept in a wet state, and further, the curing can be performed at the same level as the flooded curing. As a result, a high curing effect can be obtained, and the concrete 2 can be surely made of high quality.
Of the water w, the water that has not been absorbed by the concrete 2 is drained from the discharge channel 10e (FIG. 1).

After the concrete 2 is hardened, the mold 1 may be removed during the curing period. At this time, the fastener (not shown) between the sprinkler receiving portion 10d and the mold 1 is removed, the curing sheet 10 and the mold 1 are peeled off, and the mold 1 is removed, while as shown in FIG. In addition, the curing sheet 10 is left as it is on the surface of the concrete 2. As a result, the concrete 2 can be continuously cured even after the mold is removed. From a different point of view, demolding can be done early. As a result, the construction period can be shortened in combination with the above-mentioned promotion of curing by discharging excess water.
Even after the mold is removed, the concrete 2 may be cured in a state close to flooding by watering the watering receiving portion 10d as appropriate.
As a result, the quality of the concrete 2 can be sufficiently improved.

Then, at an arbitrary timing, preferably after the required curing period using only the curing sheet 10 is completed, the curing sheet 10 is peeled off from the concrete 2. Since the contact surface of the curing sheet 10 with the concrete 2 is composed of a water-permeable layer 11 made of a woven fabric made of a thermoplastic resin fiber or a porous resin sheet, it can be peeled off cleanly. For example, it is possible to prevent fibers derived from the curing sheet from remaining on the surface of the concrete 2. Therefore, the surface of the concrete 2 can be finished cleanly.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the sprinkler receiving portion 10d or the discharge path 10e may be omitted.
A water retention layer may be provided between the drainage layer 12 and the impermeable layer 13 of the concrete curing sheet 10. The water-retaining layer preferably has a self-absorbing property such as a water-absorbing polymer or a natural fiber non-woven fabric.
The present invention is applicable not only to cast-in-place concrete but also to the production of precast concrete.

The present invention can be applied to concrete curing work in concrete structures such as piers, retaining walls, tunnels, and buildings.

1 Concrete casting formwork (formwork)
1a Inner surface 1c Concrete casting space 2 Concrete 3 Watering nozzle 10 Concrete curing sheet 10d Watering receiving part 10e Discharge channel 11 Water permeable layer 12 Drainage layer 13 Water blocking layer 20 Woven cloth 23 Through hole 30 Perforated sheet 33 Through hole w Water

Claims (6)

A concrete curing sheet provided on the inner surface that defines the concrete casting space in the concrete casting formwork.
A permeable layer that faces the concrete placement space and allows water to pass in the thickness direction,
The impermeable impermeable layer facing the inner surface and
A drainage layer provided between the permeable layer and the impermeable layer and capable of passing water in the in-plane direction,
A concrete curing sheet characterized by being equipped with. The water permeable layer is composed of a woven fabric of a thermoplastic resin or a porous sheet.
The concrete curing sheet according to claim 1, wherein the drainage layer is made of a non-woven fabric. The concrete curing sheet according to claim 1 or 2, wherein the end portion protrudes from the formwork to form a sprinkling receiving portion for receiving water sprinkling. The water-permeable layer is characterized in that the state of close contact with the concrete placed in the concrete placing space can be maintained at the time of demolding and after the demolding of the formwork and can be peeled off from the concrete after the demolding. The concrete curing sheet according to any one of claims 1 to 3. The drainage layer thickness 0.05Mm～2.0Mm, basis weight ^{25g / m 2 ~250g / m 2} , a density of ^{0.05g / cm 3 ~1.0g / cm 3} , the thickness of the impermeable layer The concrete curing sheet according to any one of claims 1 to 4, wherein the concrete curing sheet has a total thickness of 1.0 mm or less and the total thickness of the concrete curing sheet is 10 mm or less. The concrete curing sheet according to any one of claims 1 to 5 is stretched on the inner surface defining the concrete casting space in the concrete casting formwork.
Concrete is placed in the concrete placement space,
A method of using a concrete curing sheet, which comprises supplying water to a sprinkler receiving portion formed at an end portion of the concrete curing sheet and passing water through the drainage layer during the curing period after the casting.

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