Concrete curing method and concrete curing material

Abstract

To provide a new method for curing concrete used in various building structures.SOLUTION: A concrete curing method in a site where a building structure is constructed includes: covering a surface of concrete constituting the building structure with a curing member; sealing a space between the surface and the curing member; and supplying gas containing carbon dioxide into the space. Carbon dioxide concentration of the gas is higher than carbon dioxide concentration in the atmosphere. The method may include performing surface treatment of flattening the surface by applying a pressure to the surface, and then covering the surface with the curing member.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a method for curing concrete and a component that can be used in curing concrete. [Background technology]

[0002] Concrete is used in a variety of buildings as an important structural material due to its excellent mechanical properties, weather resistance, ease of handling, and economy. Concrete is usually prepared by mixing cement, the main component, with water, aggregate, additives, etc., and the fluid concrete is poured into a formwork, hardened, and then cured. During curing, the surface of the concrete is covered with a waterproof sheet or mat to prevent water evaporation. This prevents a shortage of water necessary for cement hydration and prevents defects such as cracks caused by drying (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-107563 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide a new method for curing concrete used in various structures and a component that can be used in this method. Alternatively, an object of one embodiment of the present invention is to provide a method for efficiently fixing carbon dioxide in concrete used in structures and a component that can be used in this method. [Means for solving the problem]

[0005] One embodiment of the present invention is a method for curing concrete. The method includes, at a construction site where a structure is to be constructed, covering a surface of concrete constituting a structure with a curing material, sealing a space between the surface and the curing material, and supplying a gas containing carbon dioxide into the space. The carbon dioxide concentration of the gas is higher than the carbon dioxide concentration in the atmosphere.

[0006] One embodiment of the present invention is a component for curing concrete. The component includes a flexible sheet having an opening, and first and second rims, each having a window that overlaps with each other in a plan view. The first and second rims are configured to interlock with each other while sandwiching the peripheral edge of the flexible sheet when the flexible sheet is positioned to overlap the entire window. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a flowchart showing a concrete curing method according to an embodiment of the present invention. [Figure 2] 1A and 1B are a top view and a side view showing a concrete curing method according to one embodiment of the present invention. [Figure 3] 1A and 1B are a top view and a side view showing a concrete curing method according to one embodiment of the present invention. [Figure 4] 1A and 1B are a top view and a side view showing a concrete curing method according to one embodiment of the present invention. [Figure 5] 1A and 1B are a top view and a side view showing a concrete curing method according to one embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing a concrete curing method according to an embodiment of the present invention. [Figure 7] FIG. 1 is a top view of a protective member according to an embodiment of the present invention. [Figure 8] 1 is a top view showing a concrete curing method according to an embodiment of the present invention; [Figure 9] 1 is a cross-sectional view of a curing member according to an embodiment of the present invention. [Figure 10]1 is a top view showing a concrete curing method according to an embodiment of the present invention; [Figure 11] 1A and 1B are a top view and a side view showing a concrete curing method according to one embodiment of the present invention. [Figure 12] 1 is a perspective view showing a concrete curing method according to an embodiment of the present invention; [Figure 13] 1 is a perspective view showing a concrete curing method according to an embodiment of the present invention; [Figure 14] 1 is a perspective view showing a concrete curing method according to an embodiment of the present invention; [Figure 15] 1 is a perspective view showing a concrete curing method according to an embodiment of the present invention; [Figure 16] 1 is a perspective view showing a concrete curing method according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described in the previous drawings may be given the same reference numerals, and duplicated explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and when these are individually represented, a hyphen and a natural number are added after the reference numeral.

[0010] Hereinafter, the expression "a structure is exposed from another structure" means a state in which a part of a structure is not covered by another structure, and also includes a state in which this part not covered by another structure is covered by yet another structure.

[0011] Hereinafter, a method for curing concrete and components (curing components) applicable to this curing method will be described.

[0012] 1. Overview of curing methods FIG. 1 shows a flowchart illustrating a curing method according to one embodiment of the present invention. In this curing method, first, a basic skeleton of a building using concrete is formed. The basic skeleton may be made using steel frames or reinforcing bars, or fiber-reinforced plastic, in which resin such as epoxy resin or phenolic resin is composited with fibers such as glass fiber or carbon fiber, may be used instead of or in addition to the steel frames or reinforcing bars. The shape, configuration, and arrangement of the basic skeleton are determined appropriately based on the shape of the building, the required strength, etc. Note that this step is not required if the basic skeleton is not formed in concrete. The following explanation will be continued using an example in which the basic skeleton (reinforcing bar units) are formed using at least reinforcing bars.

[0013] Next, concrete is poured to cover the rebar units. Specifically, cement and water are mixed and kneaded. Aggregates and additives may be added as needed. Then, at the construction site, wooden, metal, or resin forms are installed to surround the rebar units, and fluid concrete is poured into the forms. At this time, compaction and pounding may be performed to remove air bubbles and excess water from the concrete, and the concrete may also be vibrated using a vibrator. If necessary, surface treatment may be performed by applying pressure to the concrete surface using a trowel or the like before the concrete hardens. Surface treatment flattens the concrete surface, further improving its appearance.

[0014] Next, carbon dioxide is supplied to the surface of the concrete before it is completely hardened, or to the surface of the hardened concrete. Specifically, the concrete surface is covered with a flexible sheet 150 (described below), with the formwork remaining, or with all or part of the formwork removed. Furthermore, the peripheral edge of the flexible sheet is fixed, and a space 156 (described below) between the concrete surface and the flexible sheet 150 is sealed. By sealing the space 156, the concrete surface is sealed.

[0015] Subsequently, a gas containing carbon dioxide is introduced into the space 156, and the carbon dioxide is brought into contact with the surface of the concrete, thereby introducing the carbon dioxide into the concrete. The carbon dioxide reacts with calcium hydroxide produced by hydration of the cement, and is fixed in the concrete as calcium carbonate. As an optional step, water may be supplied to the space 156 to adjust the humidity within the space 156.

[0016] As an optional step, the carbon dioxide concentration in space 156 may be monitored and the flow rate of the gas containing carbon dioxide may be adjusted according to the carbon dioxide concentration. Also, the humidity in space 156 may be monitored and the amount of water supplied may be adjusted according to the humidity. When curing is complete, flexible sheet 150 is removed.

[0017] There are no restrictions on the objects to which the curing method can be applied, and it can be applied to floor slab concrete, column concrete, ceiling concrete, wall concrete, etc., which are used for at least a portion of the floors, columns, ceilings, and walls of buildings. Alternatively, the curing method may be applied to concrete with a relatively large area or volume, such as muskreet for the base, footing, pile cap, etc. of large buildings. Below, we will explain in more detail the curing method and the curing members that can be used with this curing method, taking a multi-story reinforced concrete building as an example.

[0018] 2. Curing of floor slab concrete First, an embodiment of applying this curing method to the floor slab concrete of the building 100 will be described with reference to Figures 2(A) to 9. There are no restrictions on the size, shape, or design of the building 100, and this curing method can be applied to buildings that at least include concrete on the floor.

[0019] 2-1. Fabrication of rebar units First, the reinforcing bar units for the building 100 are fabricated at the construction site of the building 100. The structure and arrangement of the reinforcing bar units may be designed appropriately to suit the building 100. The building 100 illustrated in Figures 2(A) and 2(B) is composed of column reinforcing bar units 110, beam reinforcing bar units 120, and floor reinforcing bar units 130 as main reinforcing bar units.

[0020] A column reinforcing bar unit 110 is composed of a plurality of column main reinforcements 112 connected to piles (not shown), a plurality of hoops 114 arranged to surround the plurality of column main reinforcements 112, and the like. Adjacent column reinforcing bar units 110 are connected to each other by beam reinforcing bar units 120. The beam reinforcing bar unit 120 is composed of a steel frame 122, a plurality of beam main reinforcements 124 extending parallel to the steel frame 122 and fixed to the column reinforcing bar unit 110, a plurality of transverse reinforcements 126 arranged to surround the steel frame 122 and the plurality of beam main reinforcements 124, a plurality of insert bars (not shown), and the like, and is fixed to the column reinforcing bar unit 110. The beam shown here is a beam (hybrid beam) in which both ends of the steel frame 122 are covered with reinforced concrete, as will be described later, but it may also be a reinforced concrete beam made by combining a plurality of reinforcing bars without using the steel frame 122.

[0021] The floor reinforcing bar units 130 that make up the floor can be made up of, for example, metal plates (hereinafter referred to as deck plates) 132 placed on the steel frame 122, and reinforcing bar trusses placed on the deck plates 132. There are no restrictions on the structure of the reinforcing bar trusses, and the reinforcing bar trusses may be formed using hangers 134, upper main bars 136, lower main bars (not shown), and chisels connecting the upper main bars 136 and the lower main bars. Note that instead of using deck plates 132 or reinforcing bar trusses, reinforcing bar units in which multiple reinforcing bars are combined in a lattice pattern on wooden or resin plates may also be used as the floor reinforcing bar units 130.

[0022] 2-2. Installing the formwork Next, as shown in Figures 3(A) and 3(B), formwork 140, 142 is installed to surround the area where concrete will be poured. The formwork 140 is installed to determine the shape of the column concrete and beam concrete, and is installed to surround, for example, the column main reinforcement 112, the hoops 114, the transverse reinforcement 126, and a portion of the steel frame 122 surrounded by the transverse reinforcement 126. Meanwhile, the formwork 142 is installed to surround the concrete 144 to be poured on the deck plate 132 and determines the shape of the concrete 144 that will form the floor. Note that while an example is shown in which the concrete 144 that forms the columns, beams, and floor is poured simultaneously, these may be poured at different stages. Alternatively, reinforced concrete columns may be fabricated in advance and transported to and placed at the construction site of the building 100. In this case, after the columns are placed, the beam reinforcing bar units 120 and the floor reinforcing bar units 130 are fabricated, and concrete 144 is poured into the beams and floor.

[0023] 2-3. Pouring concrete Next, concrete 144 is poured into the formwork 140, 142. As a result, the concrete 144 covers the column reinforcing bar units 110 that make up the columns, the horizontal reinforcing bars 126, parts of the steel frame 122 surrounded by the horizontal reinforcing bars 126, and the reinforcing bar trusses (FIGS. 4(A) and 4(B)). The concrete 144 begins to harden. However, because the concrete 144 poured onto the deck plate 132 is exposed from the formwork 142, a surface treatment may be performed before hardening is complete, such as applying pressure to the surface with a trowel or the like to flatten the surface. The surface treatment may include, for example, performing the following steps (1) to (4) in order between immediately after pouring the concrete 144 and approximately 12 hours later. Here, the penetration resistance value in each step refers to the penetration resistance value of the concrete measured in accordance with JIA A 1147 (Test Method for Setting Time of Concrete) of the Japanese Industrial Standards. Depending on the required roughness of the surface of the concrete 144, it is possible to perform the surface treatment by selecting steps (1) only, (1) to (2), or (1) to (3), rather than performing all steps (1) to (4). (1) First step: wood trowel finishing process The concrete 144 is finished with a wooden trowel so that the surface is roughly flat. At this time, the penetration resistance of the concrete 144 is 0.5 N / mm 2 That's about it. (2) Second stage wood trowel finishing process To make the surface of the concrete 144 even smoother than in the first stage of the wood trowel finishing process, finishing is performed using a wood trowel. At this time, the penetration resistance of the concrete 144 is 2.0 N / mm 2 That's about it. (3) First step: trowel finishing process To make the surface of the concrete 144 even smoother than in the second stage wood trowel finishing process, a metal trowel is used for finishing. At this time, the penetration resistance of the concrete 144 is 3.5 N / mm 2 That's about it. (4) Second step: finishing with a gold trowel The concrete 144 is finished with a metal trowel to make the surface smoother and more mirror-like than the first stage metal trowel finish. At this time, the penetration resistance of the concrete 144 is 5N / mm 2 ~6N / mm 2 That's about it.

[0024] 2-4.Curing (1) Sealing of concrete surfaces Next, the concrete 144 poured on the deck plate 132 is cured. Curing may be performed after the concrete 144 has completely hardened, or may be performed while the concrete 144 is still fluid and not completely hardened. Curing may be performed while the formwork 142 remains in place, or after all or part of the formwork 142 has been removed. Generally, supplying carbon dioxide to the concrete 144 as soon as possible after pouring the concrete 144 and before it completely hardens accelerates the fixation of carbon dioxide (carbonation) in the concrete. It takes approximately five to seven days for the concrete 144 to harden sufficiently to allow the formwork 142 to be removed after pouring the concrete 144. Therefore, by leaving the formwork 142 in place and covering the surface of the concrete 144 before it completely hardens with a flexible sheet 150 while the concrete 144 is still inside the formwork 142, and then supplying carbon dioxide (described later), carbon dioxide can be efficiently fixed in the concrete 144 with less energy, time, and cost.

[0025] Specifically, a flexible sheet 150, which is part of a curing member according to one embodiment of the present invention, is placed so as to cover the surface of concrete 144 poured on deck plate 132 (FIGS. 5(A) and 5(B)). Flexible sheet 150 is provided so as to cover at least the surface of concrete 144 to be cured. Flexible sheet 150 may be provided so as to cover the area of ​​the surface of the floor slab concrete that is surrounded by formwork 140 that surrounds multiple columns in a plan view, or a polygonal area with multiple columns as vertices. Flexible sheet 150 may contain polymer fibers such as polyester, polyimide, or polyolefin, and its thickness may be selected from the range of 0.10 mm to 0.50 mm, for example.

[0026] Thereafter, the peripheral edge of flexible sheet 150 is fixed, and space 156 (see FIG. 6(A)) between the surface of concrete 144 and flexible sheet 150 is sealed. As a result, the surface of concrete 144 is sealed within space 156. Flexible sheet 150 may be fixed by adhering the peripheral edge of flexible sheet 150 to the surface of concrete 144 with adhesive tape (not shown). Alternatively, flexible sheet 150 may be fixed by adhering it to the remaining formwork 140 and / or 142. Note that flexible sheet 150 only needs to be fixed to the extent that a pressure higher than atmospheric pressure is maintained in space 156 when a gas containing carbon dioxide is supplied to space 156, and space 156 does not need to be kept completely airtight.

[0027] Alternatively, as shown in FIGS. 5(A) to 7(C), the flexible sheet 150 may be fixed using a sealing member 160, which is part of a curing member according to one embodiment of the present invention. The sealing member 160 may be provided so as to cover the area of ​​the surface of the floor slab concrete that is surrounded by a formwork 140 that surrounds multiple columns in a plan view, or a polygonal area with multiple columns as vertices. While there are no limitations on the configuration of the sealing member 160, for example, the sealing member 160 may be composed of two overlapping rims (a first rim 160-1 and a second rim 160-2), as shown in the cross-sectional view (FIG. 6(A)) taken along the chain line AA' in FIG. 5(A) and its enlarged partial view (FIG. 7(A)). The first rim 160-1 and the second rim 160-2 are plate-shaped members and may contain metals such as iron or aluminum, alloys such as stainless steel, or resin. When resin is used, an elastically deformable resin may be used. Specifically, a material selected from various rubbers such as diene rubbers such as natural rubber, styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, and acrylonitrile-butadiene rubber, and non-diene rubbers such as isobutylene-isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, and fluororubber can be used as the resin.

[0028] The sealing member 160 shown in Figure 5(A) is shown in Figure 6(B). As shown in Figure 6(B), the first rim 160-1 and the second rim 160-2 both have curing windows 162 as openings that overlap the surface of the concrete 144 to be cured. In other words, the sealing member 160 is configured to surround at least the portion of the concrete 144 to be cured, with this portion to be cured being exposed from the sealing member 160.

[0029] The first rim 160-1 and the second rim 160-2 are configured to interlock with each other while sandwiching the peripheral edge of the flexible sheet 150 when the flexible sheet 150 is positioned so as to overlap the entire protective window 162. There are no restrictions on the mechanism for interlocking the first rim 160-1 and the second rim 160-2, but for example, one of the first rim 160-1 and the second rim 160-2 may have a groove extending in the extension direction of the sealing member 160, and the other may have a protrusion that interlocks with the groove ( FIG. 7(B) ). By sandwiching the peripheral edge of the flexible sheet 150 between the first rim 160-1 and the second rim 160-2 and interlocking the groove and protrusion, the flexible sheet 150 can be fixed to the sealing member 160. A plurality of grooves or protrusions may be provided on the first rim 160-1 or the second rim 160-2, and through holes or bottomed holes may be used instead of grooves. The sealing member 160 may simply be placed on the surface of the concrete 144, or may be fixed to the concrete 144 or the formwork 140, 142 with adhesive tape or the like.

[0030] The first rim 160-1 may be configured to be composed of multiple detachable parts that are joined together to form the protective window 162. For example, as shown in FIGS. 7(B) and 7(C), the first rim 160-1 may include multiple parts that are configured to interlock with each other. Each of the multiple parts may be provided with a hook 160a and a notch 160b into which the hook 160a can be inserted so that the multiple parts can be fastened together. The multiple parts may be joined together to form a straight shape (FIG. 7(B)) or a curved shape (FIG. 7(C)). The same applies to the second rim 160-2. By configuring the first rim 160-1 and the second rim 160-2 from multiple parts, even a sealing member 160 with a large protective window 162 can be packed compactly and easily transported.

[0031] As shown in FIG. 8 , multiple curing members, each having a flexible sheet 150 and a sealing member 160, can be placed on the concrete 144 to cure a large-area concrete floor slab. The size of each sealing member 160 can be set arbitrarily; for example, the first rim 160-1 and the second rim 160-2 can be configured to be 5 m x 5 m or 10 m x 10 m. The size of the flexible sheet 150 can also be adjusted appropriately depending on the size of the curing window 162. Furthermore, the size of the sealing member 160 can be changed by configuring the first rim 160-1 and the second rim 160-2 with multiple parts. Furthermore, the shape of the sealing member 160 can be changed arbitrarily by appropriately combining parts that form a linear shape when connected to each other and parts that form a curved shape. This makes it possible to cure concrete floor slabs with various planar shapes.

[0032] (2) Carbon dioxide supply Flexible sheet 150 has at least one opening 152, which is configured to be connected to carbon dioxide supply source 170 via carbon dioxide line 172 (see FIG. 5(A)). Carbon dioxide line 172 may contain a metal such as copper, aluminum, or iron, or an alloy such as brass or stainless steel, or may be a flexible pipe containing a polymer such as polyethylene, vinyl chloride, polyurethane, natural rubber, silicone resin, or fluorine-containing resin.

[0033] As shown in FIG. 9(A), flexible sheet 150 may be provided with ring 157 that holds flexible sheet 150 at the periphery of opening 152, and cap 158 that closes ring 157. Ring 157 may have a female thread structure on its inner wall, and cap 158 may be a screw cap that has a male thread structure that engages with ring 157. This allows opening 152 to be closed by inserting or screwing a portion of cap 158 into ring 157. Furthermore, as shown in FIG. 9(B), by configuring the tip of carbon dioxide line 172 to also engage with ring 157, carbon dioxide line 172 can be stably fixed to opening 152, preventing carbon dioxide leakage.

[0034] As shown in Fig. 10, a flexible sheet 150 may be provided with a plurality of openings 152. In this case, carbon dioxide lines 172 are connected to the plurality of openings 152, and a gas containing carbon dioxide is supplied through these openings 152. There are no restrictions on the shape of the carbon dioxide lines 172, and the carbon dioxide lines 172 may be branched so that one carbon dioxide line 172 is connected to a plurality of openings 152, as shown in Fig. 10, or may not be branched. Alternatively, a lattice-shaped carbon dioxide line 172 may be used to connect the plurality of openings 152 to the carbon dioxide supply source 170.

[0035] The carbon dioxide supply source 170 has the function of supplying a gas containing carbon dioxide to the space 156. The gas containing carbon dioxide may be pure carbon dioxide (for example, 99% or more pure) or a mixed gas of carbon dioxide and another gas. When a mixed gas is used, the other gases may include air, oxygen, nitrogen, etc. The concentration of carbon dioxide in the mixed gas can also be set arbitrarily, but in order to efficiently bring the concrete 144 into contact with the carbon dioxide, it is preferable that the concentration be higher than the concentration of carbon dioxide contained in the atmosphere (approximately 420 ppm). For example, the carbon dioxide concentration may be set at any concentration between 1% by volume and 100% by volume.

[0036] Examples of the carbon dioxide supply source 170 include a cylinder or tank of a gas containing carbon dioxide. The carbon dioxide supply source 170 is connected to a regulator (not shown), which adjusts the pressure of the gas containing carbon dioxide. Alternatively, if there are existing facilities (such as chemical plants, waste incineration facilities, thermal power plants, and various other factories) that emit large amounts of carbon dioxide near the building 100, the gas emitted by these facilities or purified carbon dioxide obtained by subjecting the exhaust gas to dedusting, desulfurization, denitrification, and the like may be used. In this case, these facilities function as the carbon dioxide supply source 170, reducing the cost of transporting carbon dioxide and preventing further emissions of carbon dioxide associated with transportation.

[0037] When curing begins, gas containing carbon dioxide is supplied from carbon dioxide supply source 170 to space 156 through opening 152. This brings the surface of concrete 144 into contact with carbon dioxide in sealed space 156, causing the carbon dioxide to be immobilized as calcium carbonate within concrete 144. The amount of gas supplied may be determined appropriately in consideration of various parameters, such as the area of ​​concrete 144 to be cured, the volume of space 156, the cover thickness of concrete 144 (the distance between the floor reinforcing bar units and the surface of concrete 144), the concentration of carbon dioxide in the gas, the temperature during curing, and the properties of the concrete being poured. For example, the concentration of carbon dioxide in space 156 may be set appropriately within a range of 1% by volume to 100% by volume. The pressure within space 156 may be the same as atmospheric pressure or may be a positive pressure higher than atmospheric pressure. For example, the gas containing carbon dioxide may be supplied so that the pressure within space 156 is between 1 atmosphere and 1.3 atmospheres. The gas containing carbon dioxide may be supplied continuously to the space 156, but if continuous supply is not performed or is not possible, the opening 152 may be closed using a cap 158 after the gas containing carbon dioxide is supplied to the space 156.

[0038] As an optional configuration, flexible sheet 150 may have one or more openings 154 in addition to opening 152 for introducing carbon dioxide (FIGS. 5(A) and 10). Although not shown, opening 154 may also be provided with a ring or a cap that fits onto the ring. A concentration meter 164 or a hygrometer 166 for monitoring the carbon dioxide concentration and humidity, respectively, in opening 154 may be attached (FIGS. 5(A) and 6(A)). Although not shown, a thermometer for monitoring the temperature of space 156 may also be provided. These detectors, such as concentration meter 164, hygrometer 166, and thermometer, may have communication capabilities. Specifically, each may be equipped with a battery, and may be configured to periodically measure the carbon dioxide concentration, humidity, and temperature and transmit the information wirelessly or via wire to a control device or communication terminal described below.

[0039] (3) Water supply During curing, a water supply source 174 may be provided to supply water into the space 156 via a water line 176 and the opening 154 ( FIG. 10 ). Although not shown, the water supply source 174 may be equipped with a heating device or a cooling device for controlling the temperature of the supplied water. Alternatively, a carbon dioxide gas may be supplied from the carbon dioxide supply source 170 to the water supply source 174, and water containing carbon dioxide may be supplied into the space 156. Like the amount of carbon dioxide supplied, the amount of water supplied is also determined taking into account the parameters described above. Supplying water to the space 156 can control the humidity in the space 156. As a result, evaporation of water from the concrete 144 is prevented, the cement is sufficiently hydrated, and cracks in the concrete 144 caused by a lack of water necessary for cement hydration due to evaporation can be prevented.

[0040] During curing, the curing environment may be monitored using the various sensors described above. For example, a concentration meter 164 or a hygrometer 166 may be used to periodically measure the carbon dioxide concentration and humidity in the space 156. The measurement results may be transmitted to a control device or a mobile communication terminal such as a smartphone or tablet connected to the concentration meter 164 or the hygrometer 166 by wire or wirelessly. The temperature in the space 156 may also be measured using a thermometer, and the results may be transmitted.

[0041] If the carbon dioxide concentration is outside a predetermined range, the carbon dioxide supply source 170 is operated to increase or decrease the amount of carbon dioxide supplied. This operation may be performed manually or automatically. Alternatively, the carbon dioxide supply source 170 may be equipped with a communication function so that the carbon dioxide supply source 170 can be operated remotely.

[0042] Similarly, if the humidity is outside a predetermined range, the water supply source 174 is operated to increase or decrease the amount of water supplied. The humidity in the space 156 may be maintained, for example, at 50% or more and 100% or less. If the temperature in the space 156 is outside a predetermined range, the amount of water supplied may be increased or decreased, or the water temperature may be controlled using a heating or cooling device mounted on the water supply source 174. These operations may also be performed manually or automatically. Furthermore, the water supply source 174 may be equipped with a communication function so that the water supply source 174 can be operated remotely.

[0043] In this way, by using various sensors to monitor the conditions within space 156 until curing is complete, space 156 can always be kept in an environment suitable for curing concrete 144. After curing is complete, flexible sheet 150 is removed and the carbon dioxide is vented outside structure 100.

[0044] In the above-described curing method, the floor slab concrete of the building 100 can come into contact with carbon dioxide at a concentration that is extremely high compared to the carbon dioxide concentration in the atmosphere within the sealed space 156. Therefore, the carbon dioxide supplied to the space 156 can efficiently come into contact with the concrete 144, and the leakage of carbon dioxide is prevented, ensuring high safety during the curing work.

[0045] Cement, which is a raw material for concrete 144, releases a large amount of carbon dioxide during its production. However, by applying this curing method, the concrete 144 can have a high concentration of calcium carbonate, which is produced by the reaction between carbon dioxide and calcium hydroxide produced by the hydration of cement, and the concrete 144 can fix a large amount of carbon dioxide. Therefore, the curing method according to the embodiment of the present invention can be used to fix a large amount of carbon dioxide, and can contribute to reducing carbon dioxide and curbing global warming.

[0046] Known methods for immobilizing carbon dioxide in concrete include placing hardened concrete in a curing tank filled with carbon dioxide and contacting the surface of hardened porous concrete with carbon dioxide. However, these methods are difficult to apply to large structures and cannot be used when concrete is poured at the construction site.

[0047] In contrast, the curing method according to one of the present embodiments not only makes it possible to fix carbon dioxide in concrete poured at the construction site of the building 100, but also makes it possible to cure concrete of any size and area by adjusting the shape and size of the flexible sheet 150 and the sealing member 160. This makes it possible to fix a large amount of carbon dioxide. In fact, the inventors have found through preliminary experiments that this curing method can fix carbon dioxide using about 20% (60 kg / m) of the cement used. 3 ) of carbon dioxide can be fixed, and as a result, it has been confirmed that the compressive strength of concrete increases by approximately 8% to 10%. Furthermore, assuming this amount of fixed carbon dioxide, if ordinary Portland cement is used and the water / cement ratio (W / C) is 40%, and the unit cement amount is 380 kg / m 3 It has been estimated that a 100m x 100m concrete floor slab created using this method can fix a large amount of carbon dioxide, approximately 60 tons. Furthermore, the inventors' calculations show that, depending on the materials used in the concrete, it is possible to fix up to approximately 120 kg of carbon dioxide per cubic meter of concrete.

[0048] 3. Curing of pillar concrete Curing of column concrete can be performed in a similar manner. Specifically, after the concrete 144 covering the column main reinforcement bars 112 and the hoops 114 has hardened, part or all of the formwork 140 is removed. Subsequently, the surface of the concrete 144 that constitutes the column is sealed with a flexible sheet 150. For example, the flexible sheet 150 may be fixed to the column, ceiling, or floor using adhesive tape, or may be fixed to the remaining formwork 140. Alternatively, as shown in Figures 11(A) and 11(B), sealing members 160 may be provided to surround the top and bottom of the column, and the flexible sheet 150 may be fixed using the sealing members 160. As can be seen from the perspective views (FIGS. 12(A) and 12(B)) before and after placement of flexible sheet 150, sealing member 160 may be fixed to the floor slab concrete, ceiling (the underside of floor slab concrete or deck plate 132), concrete 144 constituting part of the beam, or concrete pillar, or may be fixed to the remaining formwork 140. Fixing may be performed using adhesive tape, glue, nails, or the like.

[0049] Then, gas containing carbon dioxide is introduced from the carbon dioxide supply source 170 through the opening 152. This allows a high concentration of carbon dioxide to be trapped in the space between the surface of the column concrete and the flexible sheet 150, allowing the column concrete to effectively absorb the carbon dioxide as calcium carbonate. As with the curing of floor slab concrete, water may be supplied to the space using another opening 154. Furthermore, the curing environment, i.e., the carbon dioxide concentration, humidity, temperature, etc., of the space between the flexible sheet 150 and the column concrete may be monitored during curing, and the amount of carbon dioxide-containing gas and water supplied, as well as the temperature of the water, may be controlled as appropriate. As the other configurations are the same as those for curing of floor slab concrete, detailed explanations will be omitted.

[0050] 4.Curing the ceiling concrete The ceiling concrete can be cured in a similar manner. That is, a formwork is installed in the ceiling of the building 100 (for example, under the deck plate 132), and concrete 144 is poured into the formwork to form the ceiling concrete. After the concrete 144 hardens, part or all of the formwork is removed. The ceiling concrete is then covered with a flexible sheet 150 to seal the surface of the ceiling concrete. The surface of the ceiling concrete can be sealed by fixing the flexible sheet 150 to the ceiling concrete, columns, beams, or walls using adhesive tape, or by fixing it to the remaining formwork. Alternatively, as shown in FIG. 13 , the ceiling concrete can be sealed by fixing a sealing member 160 to the beams, columns, walls, or ceiling concrete, and then fixing the flexible sheet 150 using this sealing member 160.

[0051] Then, gas containing carbon dioxide is supplied from the carbon dioxide supply source 170 to the space between the flexible sheet 150 and the ceiling concrete. This allows a high concentration of carbon dioxide to be trapped in the space between the surface of the ceiling concrete and the flexible sheet 150, and the carbon dioxide can be effectively absorbed into the ceiling concrete as calcium carbonate. As with the curing of floor slab concrete, water may be supplied to the space using other openings 154. Furthermore, the curing environment, i.e., the carbon dioxide concentration, humidity, temperature, etc., of the space between the flexible sheet 150 and the ceiling concrete may be monitored during curing, and the amount of carbon dioxide-containing gas and water supplied, and the temperature of the water may be controlled as appropriate. As the other configurations are the same as those for curing of floor slab concrete, detailed explanations will be omitted.

[0052] 5.Curing wall concrete Wall concrete can also be cured in a similar manner. That is, formwork is provided to sandwich the reinforcing bar units that make up the wall of the building 100, and concrete 144 is poured into the formwork to form the wall concrete. After the concrete 144 hardens, part or all of the formwork is removed. The wall concrete is then covered with a flexible sheet 150 to seal the surface of the wall concrete. The surface of the wall concrete can be sealed by fixing the flexible sheet 150 to the wall concrete, beams, ceiling, or floor slab concrete using adhesive tape, or by fixing the flexible sheet 150 to the remaining formwork. Alternatively, as shown in FIG. 14 , the wall concrete can be sealed by fixing a sealing member 160 to the beams, columns, ceiling, or wall concrete, and then using this sealing member 160 to fix the flexible sheet 150.

[0053] Thereafter, gas containing carbon dioxide is supplied from the carbon dioxide supply source 170 to the space between the flexible sheet 150 and the wall concrete. This allows a high concentration of carbon dioxide to be trapped in the space between the wall concrete surface and the flexible sheet 150, and the carbon dioxide can be effectively absorbed into the wall concrete as calcium carbonate. As with the curing of floor slab concrete, water may be supplied to the space using other openings 154. Furthermore, the curing environment, i.e., the carbon dioxide concentration, humidity, temperature, etc., of the space between the flexible sheet 150 and the wall concrete may be monitored during curing, and the amount of carbon dioxide-containing gas and water supplied, and the temperature of the water may be controlled as appropriate. As the other configurations are the same as those for curing of floor slab concrete, detailed explanations will be omitted.

[0054] There is no limitation on the order in which the floor slab concrete, column concrete, ceiling concrete, and wall concrete are cured, and curing may be carried out simultaneously in two or more locations.

[0055] 6. Footing curing This curing method can also be applied to the curing of mass concrete such as footings. When applying it to footings, first, as shown in Figure 15(A), multiple reinforcing bars are combined to create reinforcing bar units 182 that form the basic framework of footing 180. There are no restrictions on the number and arrangement of multiple reinforcing bars or the shape of reinforcing bar units 182, and they can be set arbitrarily according to the size and shape of footing 180 and the required strength. Furthermore, reinforcing bar units 182 may be installed directly on the ground, or on slab concrete (bare concrete) 184.

[0056] Thereafter, formwork 140 is placed around reinforcing bar units 182, and concrete 144 is poured (FIG. 15(B)). If necessary, compaction or hammering may be performed, and a vibrator may be used to vibrate concrete 144 to remove air bubbles and excess water. Furthermore, before concrete 144 hardens, surface treatment may be performed by applying pressure to the top surface of concrete 144 using a trowel or the like.

[0057] Thereafter, a flexible sheet 150 is placed on the surface of the formwork 140 or the concrete 144, for example (FIG. 16(A)). Alternatively, as shown in FIG. 16(B), part or all of the formwork 140 is removed, and the flexible sheet 150 is placed to cover the top and sides of the concrete 144. The flexible sheet 150 is then fixed in place to seal the surface of the concrete 144. The flexible sheet 150 may be fixed to the surface or sides of the concrete 144, the concrete slab 184, or the remaining formwork 140. Alternatively, as shown in FIG. 16(B), a sealing member 160 may be fixed to the ground, the concrete slab 184, or the concrete 144 so as to surround the concrete 144, and the flexible sheet 150 may be fixed using the sealing member 160.

[0058] Subsequently, a gas containing carbon dioxide is supplied to the space between the flexible sheet 150 and the concrete 144 through the opening 152, and curing is carried out. This allows a high concentration of carbon dioxide to be trapped in the space between the concrete 144 and the flexible sheet 150, and the carbon dioxide can be effectively absorbed into the concrete 144 as calcium carbonate. As with the curing of floor slab concrete, water may be supplied to the space using other openings 154. Furthermore, the curing environment, i.e., the carbon dioxide concentration, humidity, temperature, etc. of the space between the flexible sheet 150 and the footing 180, may be monitored during curing, and the amount of carbon dioxide-containing gas and water supplied, and the temperature of the water may be controlled as appropriate.

[0059] As described above, by applying the embodiments of the present invention, it is possible to effectively fix carbon dioxide in concrete used in various buildings while ensuring safety during work. This makes it possible to construct buildings with high strength. In addition, it is also possible to reduce the amount of concrete used, which contributes to reducing the construction costs of buildings.

[0060] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. A product in which a person skilled in the art appropriately adds or deletes components or modifies the design based on each embodiment is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0061] Even if there are other effects and advantages different from those brought about by the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0062] 100: Building, 110: Column reinforcing bar unit, 112: Column main bar, 114: Tie-up bar, 120: Beam reinforcing bar unit, 122: Steel frame, 124: Beam main bar, 126: Lateral reinforcement bar, 130: Floor reinforcing bar unit, 132: Deck plate, 134: Hanger, 136: Upper main bar, 140: Formwork, 142: Formwork, 144: Concrete, 150: Flexible sheet, 152: Opening, 154: Opening, 156: Space, 1 57: Ring, 158: Cap, 160: Sealing member, 160-1: First rim, 160-2: Second rim, 160a: Hook, 160b: Notch, 162: Curing window, 164: Concentration meter, 166: Hygrometer, 170: Carbon dioxide supply source, 172: Carbon dioxide line, 174: Water supply source, 176: Water line, 180: Footing, 182: Reinforced bar unit, 184: Slab concrete

Claims

1. At the site where the building is constructed, Covering the surface of the concrete constituting the building with a curing material; sealing the space between the surface and the curing member; and supplying a gas containing carbon dioxide to the space; the carbon dioxide concentration of the gas is higher than the carbon dioxide concentration in the atmosphere; The protective member includes a flexible sheet, The sealing of the surface comprises: placing a first rim on the concrete; placing the flexible sheet over the first rim such that a peripheral edge of the flexible sheet overlaps the first rim; and by placing a second rim on the first rim to sandwich the peripheral edge; A method for curing concrete, wherein one of the first rim and the second rim has a groove, and the other has a protrusion that engages with the groove.

2. 2. The concrete curing method according to claim 1, wherein the flexible sheet has an opening at a position surrounded by the second rim in a plan view, and the gas is supplied through the opening.

3. 3. The method for curing concrete according to claim 2, wherein a plurality of openings are provided in the flexible sheet, and the gas is supplied to the plurality of openings via branched carbon dioxide lines.

4. a flexible sheet having an aperture; and a first rim and a second rim each having a window that overlaps with each other in a plan view; A member for curing concrete, wherein the first rim and the second rim are configured to interlock with each other while sandwiching the peripheral edge of the flexible sheet when the flexible sheet is positioned to overlap the entire window.

5. 5. The member of claim 4, wherein one of the first rim and the second rim has a groove and the other has a protrusion that mates with the groove.

6. The member according to claim 4 , wherein the opening is configured to be openable and closable by a cap.

7. The member according to claim 4 , wherein the flexible sheet has a plurality of the openings.

8. the first rim and the second rim are composed of a plurality of detachable parts, The member according to claim 4 , wherein the plurality of parts are configured to be joined together to form the window.

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