JP7373390B2 - Concrete curing sheet and its usage - Google Patents

Description

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

After concrete is poured, it must be cured to remain moist for a certain period of time. If it dries, the hydration reaction of cement will not proceed and quality cannot be guaranteed. Therefore, it is known to provide a curing sheet containing a water retaining layer over concrete during curing (see Patent Document 1).

Japanese Patent Application Publication No. 2018-071283

The curing sheet of the above-mentioned patent document moistens and cures concrete by including a water retaining layer. However, if the amount of water retained in the water retaining layer is insufficient, it will not be possible to maintain a moist state and the curing effect will be reduced.
In view of the above circumstances, an object of the present invention is to provide a concrete curing sheet that can reliably cure poured concrete and provide a high curing effect, and a method for using the same.

In order to solve the above problems, the present invention provides a concrete curing sheet provided on the inner surface of a formwork for concrete placement that defines a concrete placement space,
a permeable layer that faces the concrete placement space and allows water to pass through in the thickness direction;
an impermeable water-blocking layer facing the inner surface;
a drainage layer provided between the water-permeable layer and the water-blocking layer and capable of passing water in an in-plane direction;
It is characterized by having the following.

When the concrete curing sheet is stretched on the inner surface of the concrete pouring form and concrete is poured into the concrete pouring space, excess water from the concrete during and immediately after pouring flows through the permeable layer in the thickness direction. It permeates and flows into the drainage layer, and can be discharged by flowing in the in-plane direction through the drainage layer. This not only promotes the hardening of the concrete, but also densifies the concrete.
Furthermore, during curing of concrete after it hardens, by passing water in the in-plane direction of the drainage layer, it is possible to perform curing similar to water-filled curing.

The water-permeable layer is composed of a woven fabric or a porous sheet of thermoplastic resin,
Preferably, the drainage layer is made of nonwoven fabric.
Thereby, the water-permeable layer can reliably allow water passage in the thickness direction, and can prevent or restrict water passage in the in-plane direction. Furthermore, water can be reliably passed in the in-plane direction of the drainage layer.
Furthermore, it is possible to prevent fibers from remaining on the concrete surface after the curing sheet is removed.
The water permeable layer and thus the concrete curing sheet can maintain a close contact with the concrete poured in the concrete placement space during and after demolding the formwork, and can be peeled from the concrete after demolding. It is preferable that there be.
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 is on the surface of the concrete. Therefore, even after demolding, the concrete can be continuously cured using the concrete curing sheet. Looking at it from a different perspective, the construction period can be shortened by removing the mold early. Thereafter, the concrete curing sheet can be peeled off from the concrete and removed at any time, preferably after the required curing period using only the concrete curing sheet has ended.

It is preferable that an end of the concrete curing sheet protrudes from the formwork and constitutes a water receiving part that receives water.
During curing of concrete after hardening, by sprinkling water on the water receiving portion, water can flow in the in-plane direction of the drainage layer, and curing can be performed on a par with flooding curing.

The water permeable layer and thus the concrete curing sheet can maintain a close contact with the concrete poured in the concrete placement space during and after demolding the formwork, and can be peeled from the concrete after demolding. It is preferable that there be.
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 is on the surface of the concrete. Therefore, even after demolding, the concrete can be continuously cured using the concrete curing sheet. Looking at it from a different perspective, the construction period can be shortened by removing the mold early. Thereafter, the concrete curing sheet can be peeled off from the concrete and removed at any time, preferably after the required curing period using only the concrete curing sheet has ended.

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 .
It is preferable that the thickness of the water-blocking layer is 1.0 mm or less.
It is preferable that the total thickness of the concrete curing sheet is 10 mm or less.

The method of the present invention is a method of using the concrete curing sheet, comprising:
Stretching the concrete curing sheet on the inner surface of a concrete casting form that defines a concrete casting space,
pouring concrete in the concrete pouring space;
In the curing period after the concrete curing sheet, water is supplied to a water receiving portion formed at an end of the concrete curing sheet to flow into the drainage layer.
As a result, during the curing of the concrete after hardening, it is possible to perform curing comparable to submergence curing, thereby improving the quality of the concrete.

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

FIG. 1 is a sectional view of a concrete casting site where concrete is being cured after being poured into a formwork provided with a concrete curing sheet according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of the concrete curing sheet. FIG. 3 is an enlarged sectional view of circular portion III in FIG. FIG. 4(a) is an enlarged plan view showing one aspect of the permeable layer of the concrete curing sheet. FIG. 4(b) is an enlarged plan view showing another aspect of the water-permeable layer of the concrete curing sheet. FIG. 5 is a sectional view of a concrete placement site showing a curing process after demolding.

An embodiment of the present invention will be described below with reference to the drawings.
Figure 1 schematically shows a concrete placement site. Concrete pouring sites are not particularly limited, and include construction sites for bridge abutments, piers, retaining walls, tunnels, dams, buildings, and other various concrete structures. A concrete pouring form 1 is installed at a concrete pouring site. A concrete placement space 1c is defined by the inner surface 1a of the formwork 1. Concrete 2 is placed in a placing 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 a water-blocking layer 13. A permeable layer 11, a drainage layer 12, and a water-blocking layer 13 are laminated in this order from the concrete placement space 1c side. The thickness direction of each layer 11, 12, 13 is along the lamination direction of layers 11, 12, 13. The water-permeable layer 11 and the drainage layer 12, and the drainage layer 12 and the water-blocking layer 13 are each joined by adhesion using an adhesive, fusion, or the like.

As shown in FIG. 3, the permeable layer 11 faces the concrete placement space 1c and is in contact with the concrete 2.
The permeable layer 11 allows water to pass through the thickness (water permeation), and prevents solids such as cement and aggregate from permeating. More preferably, the water-permeable layer 11 prevents or restricts water passage in an in-plane direction perpendicular to the thickness direction (layering direction). That is, water can hardly flow inside the permeable layer 11 in the in-plane direction.

Specifically, as shown in FIG. 4(a), 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 forms through holes 23 that allow water to pass through in the thickness direction. The size of the mesh, that is, the through holes 23, is preferably large enough to allow water to pass through and to prevent concrete particles from passing through.
Examples of the thermoplastic resin include polypropylene (PP) and polyethylene terephthalate (PET).

As shown in FIG. 4(b), the water-permeable layer 11 may be constituted by a porous sheet 30. The porous sheet 30 is made of a thermoplastic resin such as PP or PET, and is formed so that through holes 33 consisting of a large number of small holes penetrate in the thickness direction. The through holes 33 serve as water passages in the thickness direction. The size of the through hole 33 is preferably a size that allows water to pass through and prevents concrete particles from passing through.
By pouring the concrete 2 in the pouring space 1c, the permeable layer 11 is closely joined to the concrete 2. The permeable layer 11 and the curing sheet 10 can maintain a close contact with the concrete 2 during and after demolding the formwork 1 (FIG. 5), and can be forcibly separated from the concrete 2 after demolding. It is.

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

As shown in FIG. 3, the water-blocking layer 13 is in contact with the inner surface 1a of the formwork 1.
An adhesive layer for sticking to the formwork 1 may be provided on the surface of the water-blocking layer 13 on the formwork 1 side. It is preferable that the adhesive layer is removable from the formwork 1.

As shown in FIG. 2, a drainage layer 12 is interposed between the permeable layer 11 and the impermeable layer 13. The drainage layer 12 is made of, for example, a nonwoven fabric or a sponge-like open-pore porous resin. Water can pass through the drainage layer 12 in an in-plane direction (a direction perpendicular to the stacking direction of the layers 11, 12, and 13). That is, the drainage layer 12 allows water to flow inside the drainage layer 12 in an in-plane direction. At least the drainage layer 12 has higher water permeability in the in-plane direction than the water permeable layer 11. The thickness of the drainage layer 12 is greater than that of the water-permeable layer 11 and the water-blocking 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 passage space (thickness) is narrow and the drainage capacity is insufficient. If the thickness of the drainage layer 12 exceeds 2.0 m, it will be costly and uneconomical.
If the basis weight of the drainage layer 12 is less than 25 g/m ² , it will collapse under the pressure of concrete placement, making it impossible to reproduce uniform drainage capacity. 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 will be crushed by the concrete placement pressure, making it impossible to reproduce uniform drainage capacity. If the density of the drainage layer 12 exceeds 1.0 g/cm ³ , roll forming cannot be performed and productivity is poor.

Preferably, the total thickness of the concrete curing sheet 10 is 10 mm or less. If the total thickness exceeds 10 mm, the shape and dimensions of the concrete structure will be greatly affected.

As shown in FIGS. 1 and 3, for example, the upper end portion of the curing sheet 10 installed in the formwork 1 protrudes from the formwork 1 and forms a water sprinkling receiving portion 10d. Preferably, the water receiving portion 10d is bent and placed over the upper end surface of the formwork 1, and is fastened to the formwork 1 with fasteners (not shown) such as staples or nails. The water-permeable layer 11 in the water-spray receiving portion 10d constitutes the outer surface (upper surface) of the water-spray receiving portion 10d. The water-blocking layer 13 in the water receiving portion 10d faces the upper end surface of the formwork 1.
Furthermore, as shown in FIG. 1, the lower end of the curing sheet 10 is bent along the bottom surface of the formwork 1 to form a discharge path 10e. The end face of the discharge passage 10e faces the outside of the formwork 1.

The concrete curing sheet 10 is used as follows.
A curing sheet 10 is attached to the inner surface 1a of the formwork 1, and the formwork 1 is assembled.
The upper end of the curing sheet 10 serves as a water sprinkling receiving portion 10d. The lower end of the curing sheet 10 serves as a discharge path 10e.

Next, concrete 2 is placed in the space 1c within the formwork 1. The amount of water in concrete 2 during pouring should be greater than the amount required for hardening. Thereby, the fluidity of the concrete 2 can be increased and the pouring workability can be improved.
A permeable layer 11 is in contact with the concrete 2 in the space 1c. Surplus water exceeding the required amount percolates from the concrete 2 into the water-permeable layer 11, permeates through the water-permeable layer 11 in the thickness direction, and flows into the drainage layer 12. The water then flows in the in-plane direction within the drainage layer 12 and is discharged to the outside through the discharge path 10e. As a result, the hardening of the concrete 2 can be promoted, and the concrete is densified and its quality is improved by lowering the water-cement ratio W/C.
The permeable layer 11 allows water to pass in the thickness direction, while blocking or restricting the water passing in the in-plane direction, thereby uniformly discharging excess water from the entire surface of the concrete 2 (the surface in contact with the curing sheet). Can be discharged.
Solid components such as cement and aggregate in the concrete 2 cannot pass through the permeable layer 11 and can be prevented from flowing out.

After concrete 2 hardens, it is further cured for a certain period of time to ensure quality.
As shown in FIG. 1, water is sprinkled on the water receiving portion 10d continuously or as needed during the curing. For example, the water nozzle 3 is installed above the concrete casting form 1. Water w is supplied from the water sprinkling nozzle 3 to the water sprinkling receiving portion 10d.
Watering may be performed continuously, or may be performed intermittently, regularly or irregularly.
As shown by the bold line with an arrow in FIG. 11 to the concrete 2. Thereby, the concrete 2 can be reliably kept in a moist state, and furthermore, it is possible to perform curing comparable to flooding. As a result, a high curing effect can be obtained, and the concrete 2 can be reliably made of high quality.
Of the water w, the water that has not been absorbed into the concrete 2 is drained from the discharge channel 10e (FIG. 1).

After the concrete 2 hardens, the formwork 1 may be demolded during the curing period. At this time, the fasteners (not shown) between the water receiving part 10d and the formwork 1 are removed, the curing sheet 10 and the formwork 1 are peeled off, and the formwork 1 is removed. Then, the curing sheet 10 is left as it is on the surface of the concrete 2. Thereby, the concrete 2 can be continuously cured even after demolding. If you look at it differently, you can remove the mold earlier. Furthermore, in combination with the aforementioned acceleration of curing by draining excess water, the construction period can be shortened.
Even after demolding, the concrete 2 may be cured in a state similar to water-filled curing by sprinkling water on the water receiving portion 10d as appropriate.
As a result, the quality of concrete 2 can be sufficiently improved.

Thereafter, the curing sheet 10 is peeled off from the concrete 2 at an arbitrary timing, preferably after the required curing period using only the curing sheet 10 has ended. Since the contact surface of the curing sheet 10 with the concrete 2 is constituted by the water-permeable layer 11 made of a thermoplastic resin fiber woven fabric or a porous resin sheet, it can be removed cleanly. For example, fibers derived from the curing sheet can be prevented from remaining on the surface of the concrete 2. Therefore, the surface of the concrete 2 can be finished neatly.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit thereof.
For example, the water receiving portion 10d or the discharge path 10e may be omitted.
A water retaining layer may be provided between the drainage layer 12 and the impermeable layer 13 of the concrete curing sheet 10. The water-retaining layer is preferably self-absorbing, such as a water-absorbing polymer or a natural fiber nonwoven 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 construction in concrete structures such as bridge piers, retaining walls, tunnels, and buildings, for example.

1 Concrete pouring formwork (formwork)
1a Inner surface 1c Concrete casting space 2 Concrete 3 Water nozzle 10 Concrete curing sheet 10d Water receiving part 10e Drain channel 11 Permeable layer 12 Drainage layer 13 Water-blocking layer 20 Woven fabric 23 Through-hole 30 Porous sheet 33 Through-hole w Water

Claims (6)

A concrete curing sheet provided on the inner surface of a formwork for concrete placement that defines a concrete placement space,
a permeable layer that faces the concrete placement space and allows water to pass through in the thickness direction;
an impermeable water-blocking layer facing the inner surface;
a drainage layer provided between the water-permeable layer and the water-blocking layer and capable of passing water in an in-plane direction;
and the upper end of the concrete curing sheet is protruded from the upper end surface of the formwork, bent so that the permeable layer faces upward and the impermeable layer faces downward, and is placed over the upper end surface, A concrete curing sheet characterized by comprising a water sprinkling receiving portion that receives water sprinkling . The water-permeable layer is composed of a woven fabric or a porous sheet of thermoplastic resin,
The concrete curing sheet according to claim 1, wherein the drainage layer is made of a nonwoven fabric. The lower end of the concrete curing sheet is bent along the bottom surface of the formwork to form a water discharge path, and the end surface of the discharge path faces the outside of the formwork. The concrete curing sheet according to claim 1 or 2. The water-permeable layer is characterized in that it can maintain a state of close contact with the concrete poured in the concrete placement space during and after demolding the formwork, and can be peeled from the concrete after demolding. The concrete curing sheet according to any one of claims 1 to 3. 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 , and the thickness of the water blocking layer is 5. The concrete curing sheet according to claim 1, wherein the concrete curing sheet has a total thickness of 1.0 mm or less and a total thickness of 10 mm or less. Stretching the concrete curing sheet according to any one of claims 1 to 5 on the inner surface of a formwork for concrete placement that defines a concrete placement space,
pouring concrete in the concrete pouring space;
A method for using a concrete curing sheet, characterized in that during the curing period after the concrete is placed, water is supplied to the water receiving portion and passed through the drainage layer.

Images