Sheets for curing concrete after pouring

Abstract

This design ensures reliable drainage of excess water during concrete placement and supply of curing water during concrete curing, while also improving workability by reducing the sheet thickness and weight. [Solution] The concrete curing sheet 1 consists of a liquid-permeable sheet 3 placed on the concrete 2 side, a hollow fiber membrane 4 placed on the non-concrete side of the liquid-permeable sheet 3, and a pump 5 connected to the hollow fiber membrane 4, which is capable of supplying water to the hollow fiber membrane 4 and draining water from within the hollow fiber membrane 4. The pump 5 ensures reliable drainage of excess water during concrete placement and supply of curing water during concrete curing. Since drainage during concrete placement and water supply during concrete curing are forcibly performed by the pump 5, a sheet layer for water passage or liquid retention is unnecessary, allowing for a thinner overall sheet thickness and improved workability due to weight reduction.

Description

Technical Field

[0001] The present invention relates to a sheet that can be used for both concrete placement and curing.

Background Art

[0002] Conventionally, when placing concrete, in order to discharge excess water and air bubbles, a drainage sheet is attached to the surface of the formwork, thereby suppressing the occurrence of surface defects of the concrete structure and improving the quality of the concrete structure.

[0003] For example, Patent Document 1 below discloses a sheet for a concrete placement formwork interposed between a concrete placement formwork and placed concrete, which comprises a water-permeable base material, an impermeable film laminated on the surface of the base material on the formwork side, and a water-permeable film provided with a large number of fine through-holes for water permeation laminated on the surface of the base material on the concrete placement side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1, mentioned above, describes a method that combines the functions of a conventional drainage sheet and a curing sheet by ensuring that excess water in the poured concrete is reliably drained immediately after pouring, and by remaining on the concrete surface when demolding, it also functions as a curing sheet for the hardened concrete. However, in the case of use as a drainage sheet, the excess water absorbed by the water-permeable base material is drained using surface tension and gravity, so there is a risk that the drainage will not keep up with the amount of excess water generated. In the case of use as a curing sheet, only the amount of water held in the water-permeable base material can be used as curing water, so there is a risk of insufficient curing water. Furthermore, in order to ensure a sufficient amount of curing water, the sheet thickness must be increased in order to ensure the water retention capacity of the water-permeable base material, which has the disadvantage of increasing the weight and thus having the disadvantage of poor workability.

[0006] Therefore, the main objective of the present invention is to provide a concrete curing sheet that can reliably drain excess water during concrete placement and supply curing water during concrete curing, while also allowing for a thinner sheet thickness and improved workability through weight reduction. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present invention according to claim 1 provides a concrete pouring and curing sheet that allows for the drainage of excess water during concrete pouring and the supply of curing water during concrete curing, A concrete curing sheet is provided, characterized by comprising a liquid-permeable sheet placed on the concrete side, a hollow fiber membrane placed on the non-concrete side of the liquid-permeable sheet, and a pump connected to the hollow fiber membrane that is capable of supplying water to the hollow fiber membrane and draining water from within the hollow fiber membrane.

[0008] In the invention described in claim 1 above, a liquid-permeable sheet is placed on the concrete side of the concrete curing sheet, a hollow fiber membrane is placed on the non-concrete side of the liquid-permeable sheet, and water is supplied to and drained from the hollow fiber membrane by a pump connected to the hollow fiber membrane. Therefore, when concrete is poured, the concrete curing sheet is attached to the surface of the formwork and sucked by the pump, causing excess water to be absorbed by the liquid-permeable sheet, then taken into the hollow fiber membrane through numerous micropores provided on the circumferential surface of the hollow fiber membrane, and drained. After that, when the formwork is removed, the concrete curing sheet is left on the concrete surface to allow the concrete to be moist-cured. During concrete curing, water is supplied by the pump, causing curing water to seep out through numerous micropores provided on the circumferential surface of the hollow fiber membrane, and the concrete surface is kept moist through the liquid-permeable sheet.

[0009] Thus, the concrete curing sheet according to the present invention can reliably drain excess water during concrete placement and supply curing water during concrete curing by supplying and draining water from a pump connected to the hollow fiber membrane.

[0010] Furthermore, since the drainage of excess water during concrete placement and the supply of curing water during concrete curing are forcibly carried out by the supply and drainage of a pump connected to a hollow fiber membrane, a sheet layer for water passage and a sheet layer for liquid retention are unnecessary. This allows for a thinner overall sheet thickness and improves workability through weight reduction.

[0011] As part of the present invention according to claim 2, a concrete curing sheet according to claim 1 is provided, wherein the liquid permeable sheet is formed of a cushioning material.

[0012] In the invention described in claim 2 above, a cushioning material is used as the liquid permeable sheet in order to prevent the marks of the hollow fiber membrane, which is arranged on the non-concrete side of the liquid permeable sheet, from being left on the concrete surface due to the pressure of the concrete when the concrete is poured.

[0013] As part of the present invention according to claim 3, a concrete curing sheet according to claim 1 is provided, wherein the liquid permeable sheet is made of either a woven fabric or a nonwoven fabric or a combination thereof.

[0014] In the invention described in claim 3 above, the liquid-permeable sheet is made of woven fabric or nonwoven fabric, or a combination of woven fabric and nonwoven fabric.

[0015] As part of the present invention according to claim 4, a concrete curing sheet for concrete placement is provided, wherein a laminated sheet is arranged on the non-concrete side of the liquid permeable sheet, and the hollow fiber membrane is arranged between the liquid permeable sheet and the laminated sheet, as described in claim 1.

[0016] In the invention described in claim 4 above, the concrete curing sheet has a structure in which the hollow fiber membrane is arranged between a liquid-permeable sheet and a laminated sheet. Therefore, when concrete is placed, excess water absorbed by the liquid-permeable sheet is easily drained by the hollow fiber membrane, and when the concrete is cured, the curing water supplied from the hollow fiber membrane makes it easier to keep the concrete surface moist.

[0017] As part of the present invention according to claim 5, a concrete curing sheet according to claim 4 is provided, wherein the laminated sheet is a liquid-impermeable sheet.

[0018] In the invention described in claim 5 above, since a liquid-impermeable sheet is used as the laminated sheet laminated on the non-concrete side of the liquid-permeable sheet, the drying of the curing water supplied from the hollow fiber membrane during concrete curing is suppressed, and the concrete surface can be more reliably kept moist.

[0019] As the invention according to claim 6, there is provided a concrete placing and curing sheet according to claim 1, which incorporates a sensor capable of measuring the wet state of the concrete surface, and the water supply by the pump is managed according to the measured value of the sensor during curing.

[0020] In the invention according to claim 6 above, a sensor capable of measuring the wet state of the concrete surface is incorporated in the concrete placing and curing sheet, and during concrete curing, the water supply by the pump is managed according to the measured value of this sensor. Therefore, wet curing can be performed while reliably maintaining the wet state of the concrete surface.

Effect of the Invention

[0021] As described in detail above, according to the present invention, drainage of surplus water during concrete placing and water supply of curing water during concrete curing can be surely performed, and the sheet thickness can be made thinner, so that the workability can be improved by weight reduction.

Brief Description of the Drawings

[0022] [Figure 1] (A) shows the placement state of the concrete placing and curing sheet 1 during concrete placing, and (B) shows the placement state of the concrete placing and curing sheet 1 during concrete curing, which is a cross-sectional view. [Figure 2] It is a cross-sectional view of the concrete placing and curing sheet 1 when using the liquid-permeable sheet 3 provided with the cushion material 3a. [Figure 3] It is a plan view of the concrete placing and curing sheet 1 showing the arrangement pattern (the first one) of the hollow fiber membrane 4. [Figure 4] It is a plan view of the concrete placing and curing sheet 1 showing the arrangement pattern (the second one) of the hollow fiber membrane 4. [Figure 5] (A) shows the water supply and drainage state of the hollow fiber membrane 4 during concrete placing, and (B) shows the water supply and drainage state of the hollow fiber membrane 4 during concrete curing, which is a schematic diagram.

Mode for Carrying Out the Invention

[0023] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0024] The concrete curing sheet 1 according to the present invention is intended to improve the quality and durability of concrete by enabling the drainage of excess water during concrete placement and the supply of curing water during concrete curing.

[0025] The concrete curing sheet 1 according to the present invention, as shown in Figure 1, consists of a liquid-permeable sheet 3 placed on the concrete 2 side, a hollow fiber membrane 4 placed on the non-concrete side of the liquid-permeable sheet 3, and a pump 5 connected to the hollow fiber membrane 4, which is capable of supplying water to the hollow fiber membrane 4 and draining water from within the hollow fiber membrane 4.

[0026] The liquid-permeable sheet 3 is a sheet that allows liquid to pass through, composed of either a hydrophilic woven fabric or a nonwoven fabric, or a combination thereof. Examples of combinations of woven and nonwoven fabrics include laminated sheets of woven and nonwoven fabrics. The liquid-permeable sheet 3 may be composed of a single layer or a composite laminate formed by laminating two or more layers of different types of sheet materials.

[0027] The material fibers constituting the woven or nonwoven fabric can include, for example, synthetic fibers such as polyethylene or polypropylene (olefin-based), polyester, or polyamide, as well as regenerated fibers such as rayon or cupro, and natural fibers such as cotton or linen.

[0028] The liquid permeable sheet 3 is preferably made of a cushioning material. It is particularly desirable that the liquid permeable sheet 3 has a structure in which a nonwoven fabric sheet 3b is laminated onto the concrete-side surface of a cushioning material 3a, as shown in Figure 2. The cushioning properties of the liquid permeable sheet 3 prevent the placement marks of the hollow fiber membrane 4 from remaining on the concrete surface when pressure is applied from the concrete side during concrete placement. To provide cushioning to the liquid permeable sheet 3, foams of resin materials such as polyethylene or polyurethane are suitably used. This foam is a porous material with numerous interconnected air bubbles and has elasticity in the thickness direction, allowing it to conform to the irregularities of the hollow fiber membrane 4 and suppress the placement marks of the hollow fiber membrane 4 on the concrete-facing surface.

[0029] Such a cushioning liquid-permeable sheet 3 is formed with a thickness greater than the outer diameter of the hollow fiber membrane 4, in order to prevent the placement marks of the hollow fiber membrane 4, and has an appropriate elastic force that can withstand the pressure it receives when concrete 2 is poured.

[0030] As shown in Figure 3, the hollow fiber membrane 4 is arranged on the non-concrete side of the liquid-permeable sheet 3 in two-dimensional geometric shapes, such as patterns drawn in a single stroke, like a wavy pattern, a zigzag pattern, or a meander pattern, or as shown in Figure 4, patterns extending linearly from a predetermined chamber section 4a. Water is drawn in or supplied to the membrane by a pump 5 connected to it.

[0031] The hollow fiber membrane 4 is a hollow tube with numerous micropores formed on its circumferential surface, and is used with an outer diameter of approximately 0.2 to 5.0 mm, preferably 0.5 to 1.0 mm. The hollow fiber membrane 4 is arranged with one end connected to the pump 5 and the other end closed or open. The pump 5 provides water supply and drainage, and as shown in Figure 5(A), it has the function of creating negative pressure inside the hollow interior of the hollow fiber membrane 4, drawing in surrounding water through the micropores on the circumferential surface or the open other end, collecting and draining water through the hollow interior which acts as a water channel. As shown in Figure 5(B), it also has the function of supplying water from the pump 5 to the hollow interior of the hollow fiber membrane 4, causing water to seep out to the outside through the micropores on the circumferential surface or the open other end.

[0032] As for the pump 5, any known pump can be used without limitation, as long as it is connected to one end of the hollow fiber membrane 4 and has a mechanism capable of supplying water to the hollow fiber membrane 4 and draining water from within the hollow fiber membrane 4. The pump 5 may consist of a single pump capable of switching between water supply and drainage by reversing the direction of rotation, or two pumps, one for water supply and one for drainage, may be used, with the drainage pump connected during concrete placement and the water supply pump connected during concrete curing.

[0033] As shown in Figure 1, the laminated sheet 6 may be placed on the non-concrete side of the liquid-permeable sheet 3, and the hollow fiber membrane 4 may be placed between the liquid-permeable sheet 3 and the laminated sheet 6.

[0034] As the laminated sheet 6, a permeable or impermeable sheet can be used, but it is preferable to use an impermeable sheet. Examples of permeable sheets include those made of the same material fibers as the permeable sheet 3, and examples of impermeable sheets include those made of olefin resin sheets such as polyethylene or polypropylene, which have at least water-impermeable properties. Other examples include laminated nonwoven fabrics made by laminating a nonwoven fabric onto a polyethylene sheet, and nonwoven fabric sheets that have substantially liquid impermeability through the interposition of a waterproof film. When an impermeable sheet is used as the laminated sheet 6, the drying of moisture from the surface of the concrete 2 during concrete curing is suppressed, making it possible to more reliably maintain the surface of the concrete 2 in a moist state.

[0035] When the concrete curing sheet 1 is placed on a vertically standing wall or an inclined slope, the arrangement pattern of the hollow fiber membrane 4 should be such that the direction in which the hollow fiber membrane 4 mainly extends (vertical direction in the arrangement pattern of Figure 2, horizontal direction in the arrangement pattern of Figure 3) coincides with the vertical direction of the wall or is in a substantially horizontal direction perpendicular to the vertical direction of the wall. When the direction in which the hollow fiber membrane 4 mainly extends coincides with the vertical direction of the wall, during concrete placement, excess water absorbed by the liquid permeable sheet 3 flows downward due to gravity, and is gradually absorbed into the hollow fiber membrane 4 as it is drawn in the direction of the parallel hollow fiber membrane 4. This allows for drainage that combines drainage by the hollow fiber membrane 4 and drainage by gravity through the liquid permeable sheet 3. On the other hand, when the hollow fiber membrane 4 is positioned in a substantially horizontal direction perpendicular to the vertical direction of the wall surface, during concrete placement, excess water absorbed by the liquid-permeable sheet 3 is absorbed by the hollow fiber membrane 4 as it flows downward due to gravity, effectively blocking the flow. This ensures reliable drainage. Furthermore, during concrete curing, curing water seeping out from the micropores on the periphery of the hollow fiber membrane 4 is diffused almost uniformly across the entire surface of the liquid-permeable sheet 3, enabling reliable wet curing.

[0036] Next, the method of using the concrete curing sheet 1 will be described. When concrete is poured, the concrete curing sheet 1 is attached to the surface of the formwork 7 (the surface facing the concrete 2) as shown in Figure 1(A). To facilitate the attachment of the concrete curing sheet 1, an adhesive layer may be provided on the surface of the concrete curing sheet 1 facing the formwork 7.

[0037] During concrete placement, excess water generated by suction with the pump 5 permeates the liquid-permeable sheet 3, penetrates into the hollow fiber membrane 4 through micropores on its circumferential surface, and is then drained away.

[0038] Subsequently, once it is confirmed that the compressive strength of the concrete has reached the design standard strength and that there are no problems with demolding, the formwork 7 is removed. When demolding, the concrete curing sheet 1 is peeled off from the formwork 7, and only the formwork 7 is removed, leaving the concrete curing sheet 1 on the surface of the concrete 2, and wet curing is continued. This ensures that the strength is increased thereafter, and the concrete structure becomes denser, increasing its resistance to carbonation.

[0039] During concrete curing, water is supplied by pump 5, causing curing water to seep out through the micropores on the periphery of the hollow fiber membrane 4, permeate the liquid-permeable sheet 3, and keep the surface of the concrete 2 moist. This moist curing is continued for a predetermined number of days or until the concrete reaches a predetermined strength.

[0040] During the curing period, water can be supplied by pump 5 at a constant rate throughout the curing period, or water can be supplied and stopped at regular intervals.

[0041] Alternatively, the concrete curing sheet 1 may be equipped with a sensor capable of measuring the surface moisture level of the concrete 2, and the water supply by the pump 5 may be managed according to the measurement value of the sensor during curing. This eliminates the wasteful supply of curing water and prevents drying shrinkage caused by insufficient moisture during wet curing.

[0042] Once the prescribed curing period has elapsed, the water supply to pump 5 is stopped and the concrete curing sheet 1 is removed.

[0043] The removed concrete curing sheet 1 can be washed with water and reused.

[0044] As described above, the concrete curing sheet 1 according to the present invention can reliably drain excess water during concrete placement and supply curing water during concrete curing by switching the water supply and drainage of the pump 5 connected to the hollow fiber membrane 4.

[0045] Furthermore, since the drainage of excess water during concrete placement and the supply of curing water during concrete curing are forcibly carried out by the pump 5 connected to the hollow fiber membrane 4, a sheet layer for water passage and a sheet layer for liquid retention are unnecessary, allowing for a thinner overall sheet thickness and improved workability due to weight reduction. In addition, uniform water supply and drainage can be achieved even on horizontal surfaces such as floor slabs where there is little movement of excess water or curing water due to gravity.

[0046] [Other examples of forms] In the above example, a cushioning material was used on the liquid-permeable sheet 3 placed on the concrete side of the hollow fiber membrane 4. However, a cushioning material may also be placed on the laminated sheet 6 placed on the non-concrete side of the hollow fiber membrane 4. By sinking into the cushioning material on the non-concrete side, it becomes less likely for the hollow fiber membrane 4 to leave a mark on the concrete side. Furthermore, in order to allow drainage through the micropores on the circumferential surface of the hollow fiber membrane 4 even when the hollow fiber membrane 4 sinks into the cushioning material on the non-concrete side, it is preferable to use a liquid-permeable cushioning material and laminate a liquid-impermeable sheet on its non-concrete side to form the laminated sheet 6. [Explanation of Symbols]

[0047] 1... Sheet for curing concrete pouring, 2... Concrete, 3... Liquid permeable sheet, 4... Hollow fiber membrane, 5... Pump, 6... Laminated sheet, 7... Formwork

Claims

1. A concrete pouring and curing sheet that allows for the drainage of excess water during concrete pouring and the supply of curing water during concrete curing, A concrete curing sheet characterized by comprising a liquid-permeable sheet placed on the concrete side, a hollow fiber membrane placed on the non-concrete side of the liquid-permeable sheet, and a pump connected to the hollow fiber membrane that is capable of supplying water to the hollow fiber membrane and draining water from within the hollow fiber membrane.

2. The concrete curing sheet according to claim 1, wherein the liquid-permeable sheet is formed of a cushioning material.

3. The sheet for curing concrete pouring according to claim 1, wherein the liquid-permeable sheet is made of either a woven fabric or a nonwoven fabric or a combination thereof.

4. The concrete curing sheet according to claim 1, wherein a laminated sheet is arranged on the non-concrete side of the liquid-permeable sheet, and the hollow fiber membrane is arranged between the liquid-permeable sheet and the laminated sheet.

5. The concrete curing sheet according to claim 4, wherein the laminated sheet is a liquid-impermeable sheet.

6. The concrete curing sheet according to claim 1, which has a built-in sensor capable of measuring the moisture level of the concrete surface, and during curing, controls the water supply by the pump according to the measurement value of the sensor.

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