Concrete curing method and concrete curing member

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 various buildings as an important structural material due to its excellent mechanical properties, weather resistance, ease of handling, and cost-effectiveness. Concrete is usually prepared by mixing the main component, cement, with water, aggregate, additives, etc., and the concrete in a fluid state 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 evaporation of water. This prevents a shortage of water necessary for hydration of the cement, and can prevent defects such as cracks caused by drying (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-107563 A 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 member 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 member 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, comprising: covering a surface of concrete constituting a structure with a curing material at a site where the structure is to be constructed; sealing a space between the surface and the curing material; 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.

[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 description of the drawings]

[0007] [Figure 1] 1 is a flowchart showing a concrete curing method according to an embodiment of the present invention. [Diagram 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. [Diagram 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. [Diagram 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. 2 is a top view of a covering member according to one embodiment of the present invention. [Figure 8] FIG. 2 is a top view showing a method for curing concrete according to one embodiment of the present invention. [Figure 9] FIG. 2 is a cross-sectional view of a curing member according to one embodiment of the present invention. [Figure 10]FIG. 2 is a top view showing a method for curing concrete according to one 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 PREFERRED EMBODIMENTS

[0008] Hereinafter, each embodiment 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 gist of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In the drawings, the width, thickness, shape, etc. of each part may be shown diagrammatically compared to the actual embodiment in order to make the explanation clearer, but it is merely an example and does not limit the interpretation of the present invention. In this specification and each figure, elements having the same function as those explained in the previous figures may be given the same reference numerals and duplicate explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and a hyphen and a natural number are added after the reference numeral to represent each of them individually.

[0010] Hereinafter, the expression "a certain structure is exposed from another structure" means a state in which a part of a certain structure is not covered by another structure, and also includes a state in which the part not covered by the other 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 method FIG. 1 shows a flow chart illustrating a curing method according to one embodiment of the present invention. In this curing method, first, a basic skeleton of a structure using concrete is formed. The basic skeleton may be made using steel frames or reinforcing bars, or fiber-reinforced plastics in which resins such as epoxy resins or phenolic resins are combined with fibers such as glass fibers or carbon fibers may be used instead of or together with the steel frames or reinforcing bars. The shape, configuration, and arrangement of the basic skeleton are appropriately determined based on the shape of the structure and the required strength. Note that this step is not required when the basic skeleton is not formed in the concrete. Below, the 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 reinforcing bar units. Specifically, cement and water are mixed and kneaded. At this time, aggregates and additives may be added as appropriate. Then, at the site where the building is to be constructed, a wooden, metal, or resin formwork is attached to surround the reinforcing bar units, and concrete in a fluid state is poured into the formwork. At this time, in order to remove air bubbles and excess water mixed into the concrete, compaction work or tapping work may be performed, and further, vibration may be applied to the concrete using a vibrator. If necessary, before the concrete hardens, pressure may be applied to the concrete surface using a trowel or the like to perform surface treatment. By performing surface treatment, the concrete surface is flattened, and the aesthetic appearance is further improved.

[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, which will be described later, with the formwork remaining, or with all or part of the formwork removed. Furthermore, the peripheral portion of the flexible sheet is fixed, and a space 156 (described later) 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 in 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 the curing is completed, flexible sheet 150 is removed.

[0017] There are no restrictions on the objects to which the curing method can be applied, and the method 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 method can be applied to concrete having a relatively large area or volume, such as muskreat for the base, footing, pile cap, etc., of large buildings. Below, the method and curing members that can be used in the method will be described in more detail, taking a multi-story reinforced concrete building as an example.

[0018] 2.Curing floor slab concrete First, a mode of applying this curing method to the floor slab concrete of the building structure 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 structure 100, and this curing method can be applied to buildings that at least include concrete on the floor.

[0019] 2-1. Manufacturing rebar units First, 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 appropriately designed 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] The column reinforcing bar unit 110 is composed of a plurality of column main bars 112 connected to piles (not shown), a plurality of hoops 114 arranged to surround the plurality of column main bars 112, and the like. Adjacent column reinforcing bar units 110 are connected to each other by a beam reinforcing bar unit 120. The beam reinforcing bar unit 120 is composed of a steel frame 122, a plurality of beam main bars 124 extending parallel to the steel frame 122 and fixed to the column reinforcing bar unit 110, a plurality of transverse reinforcing bars 126 arranged to surround the steel frame 122 and the plurality of beam main bars 124, a plurality of plugs (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 described later, but it may 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 composed of, for example, a metal plate material (hereinafter, deck plate) 132 provided on the steel frame 122, and a reinforcing bar truss placed on the deck plate 132. There are no restrictions on the structure of the reinforcing bar truss, and the reinforcing bar truss may be formed using hanging members 134, upper main bars 136, lower main bars (not shown), and a chisel material that connects the upper main bars 136 and the lower main bars. Note that instead of using the deck plate 132 or reinforcing bar truss, a reinforcing bar unit in which multiple reinforcing bars are combined in a lattice pattern on a wooden or resin plate material may be used as the floor reinforcing bar unit 130.

[0022] 2-2. Installation of formwork Next, as shown in FIG. 3(A) and FIG. 3(B), formwork 140, 142 is attached to surround the portion where concrete is poured. The formwork 140 is provided to determine the shape of the column concrete and the beam concrete, and is provided to surround, for example, the column main reinforcement 112, the hoop reinforcement 114, the horizontal reinforcement 126, and a part of the steel frame 122 surrounded by the horizontal reinforcement 126. On the other hand, the formwork 142 is provided to surround the concrete 144 poured on the deck plate 132, and determines the shape of the concrete 144 that constitutes the floor. Note that, although an example is shown here in which the concrete 144 that constitutes the columns, beams, and floor is poured at the same time, these may be poured at different stages. Also, columns made of reinforced concrete may be fabricated in advance, and transported to the site where the building structure 100 is constructed and placed there. In this case, after the columns are placed, the beam reinforcing bar unit 120 and the floor reinforcing bar unit 130 are fabricated, and the 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 column reinforcing bar unit 110 constituting the column, the horizontal reinforcing bar 126, a part of the steel frame 122 surrounded by the horizontal reinforcing bar 126, the reinforcing bar truss, etc. are covered with the concrete 144 (FIGS. 4(A) and 4(B)). The concrete 144 starts to harden, but since the concrete 144 poured on the deck plate 132 is exposed from the formwork 142, a surface treatment may be performed before the hardening is completed by applying pressure to the surface using 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 from immediately after pouring the concrete 144 to about 12 hours later. Here, the penetration resistance value in each step indicates the penetration resistance value of the concrete measured in accordance with JIA A 1147 (Concrete Setting Time Test Method) in 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) through (2), or (1) through (3), rather than performing all steps (1) through (4). (1) First stage: wood trowel finishing process The concrete 144 is finished with a wooden trowel so that the surface of the concrete 144 is roughly flat. At this time, the penetration resistance of the concrete 144 is 0.5 N / mm 2 That's about it. (2) The second step is the wood trowel finishing process. In order 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 In order to make the surface of the concrete 144 even smoother than in the second step of the wood trowel finishing process, a metal trowel is used to finish the surface. The penetration resistance of the concrete 144 is 3.5 N / mm 2 That's about it. (4) Second step: trowel finish In order to make the surface of the concrete 144 even smoother and more mirror-like than the first stage of trowel finishing, a metal trowel is used to finish the concrete 144. 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 cast on the deck plate 132 is cured. The curing may be performed after the concrete 144 has completely hardened, or may be performed while the concrete 144 is not completely hardened and has fluidity. The curing may be performed while the entire formwork 142 remains, or may be performed after all or a part of the formwork 142 is removed. Generally, if carbon dioxide is supplied to the concrete 144 as soon as possible after the concrete 144 is cast and before the concrete 144 is completely hardened, the fixation of carbon dioxide (carbonation) in the concrete progresses quickly. Also, it takes about 5 to 7 days from casting the concrete 144 until the concrete 144 hardens to the extent that the formwork 142 can be removed. For this reason, the surface of the concrete 144 before it is completely hardened is covered with the flexible sheet 150 while the entire formwork 142 remains and the concrete 144 is present within the formwork 142, and carbon dioxide is supplied to the concrete 144, as described below, so that carbon dioxide can be efficiently fixed in the concrete 144 with less energy, time, and cost.

[0025] Specifically, a flexible sheet 150, which is a part of a curing member according to one embodiment of the present invention, is arranged 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 an area of ​​the surface of 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, and polyolefin, and the thickness may be selected, for example, from the range of 0.10 mm to 0.50 mm.

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

[0027] Alternatively, as shown in Fig. 5(A) to Fig. 7(C), the flexible sheet 150 may be fixed using a sealing member 160, which is a part of a curing member according to one embodiment of the present invention. The sealing member 160 may be provided so as to cover an area of ​​the surface of the floor slab concrete that is surrounded by a formwork 140 that surrounds a plurality of columns in a plan view, or a polygonal area with a plurality of columns as vertices. There are no restrictions on the configuration of the sealing member 160, but 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 a cross-sectional view (Fig. 6(A)) taken along the chain line AA' in Fig. 5(A) and an enlarged view (Fig. 7(A)) of a part of the cross-sectional view. The first rim 160-1 and the second rim 160-2 are plate-shaped members and may contain metals such as iron and 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 Fig. 5(A) is shown in Fig. 6(B). As shown in Fig. 6(B), the first rim 160-1 and the second rim 160-2 each have a curing window 162 as an opening that overlaps with 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, and this portion to be cured is exposed from the sealing member 160.

[0029] The first rim 160-1 and the second rim 160-2 are configured to engage with each other while sandwiching the peripheral portion of the flexible sheet 150 when the flexible sheet 150 is arranged to overlap the entire protective window 162. There are no restrictions on the mechanism for engaging 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 along the direction in which the sealing member 160 extends, and the other may have a protrusion that engages with the groove (FIG. 7(B)). The flexible sheet 150 can be fixed to the sealing member 160 by sandwiching the peripheral portion of the flexible sheet 150 between the first rim 160-1 and the second rim 160-2 and engaging the groove with the protrusion. A plurality of grooves or protrusions may be provided on the first rim 160-1 or the second rim 160-2, and a through hole or a bottomed hole may be used instead of the groove. 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 a plurality of detachable parts, which are joined together to form the protective window 162. For example, as shown in FIG. 7(B) or FIG. 7(C), the first rim 160-1 may include a plurality of parts configured to mesh with each other. Each of the plurality of parts may be provided with a hook 160a and a notch 160b into which the hook 160a can be inserted so that the plurality of parts can be fixed together. The plurality of parts may be joined together to form a straight shape (FIG. 7(B)), or may be bent (FIG. 7(C)). The same applies to the second rim 160-2. By forming the first rim 160-1 or the second rim 160-2 from a plurality of parts, even a sealing member 160 having a large protective window 162 can be packed compactly and easily transported.

[0031] As shown in FIG. 8, by arranging a plurality of curing members each having a flexible sheet 150 and a sealing member 160 on the concrete 144, it is possible to perform curing on a floor slab concrete having a large area. The size of each sealing member 160 may be set arbitrarily, for example, the first rim 160-1 and the second rim 160-2 may be configured to be 5m×5m or 10m×10m. The size of the flexible sheet 150 may also be appropriately adjusted according to the size of the curing window 162. In addition, by configuring the first rim 160-1 and the second rim 160-2 each with a plurality of parts, the size of the sealing member 160 can be changed. In addition, by appropriately combining parts that form a linear shape by being connected to each other and parts that form a curved shape, the shape of the sealing member 160 can also be arbitrarily changed. For this reason, it is also possible to cure floor slab concrete having 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 source 170 via carbon dioxide line 172 (see FIG. 5(A)). Carbon dioxide line 172 may include a metal such as copper, aluminum, or iron, or an alloy such as brass or stainless steel, or may be a flexible pipe including a polymer such as polyethylene, polyvinyl 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 the inner wall, and cap 158 may be a screw cap having a male thread structure that meshes with ring 157. This allows opening 152 to be closed by inserting or screwing a part of cap 158 into ring 157. Also, as shown in FIG. 9(B), by configuring the tip of carbon dioxide line 172 to mesh with ring 157, carbon dioxide line 172 can be stably fixed to opening 152, and carbon dioxide leakage can be prevented.

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

[0035] The carbon dioxide supply source 170 has a function of supplying a gas containing carbon dioxide to the space 156. The gas containing carbon dioxide may be pure carbon dioxide (e.g., purity of 99% or more) 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 is higher than the concentration of carbon dioxide contained in the atmosphere (approximately 420 ppm). For example, the carbon dioxide concentration may be set arbitrarily from 1% by volume to 100% by volume.

[0036] The carbon dioxide supply source 170 may be, for example, a cylinder or tank of a gas containing carbon dioxide. The carbon dioxide supply source 170 is connected to a regulator (not shown) to adjust 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 dust removal, 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 emission of carbon dioxide associated with the transportation.

[0037] When curing is started, a gas containing carbon dioxide is supplied from a carbon dioxide supply source 170 to the space 156 through the opening 152. As a result, the surface of the concrete 144 comes into contact with the carbon dioxide in the sealed space 156, and the carbon dioxide is fixed as calcium carbonate in the concrete 144. The amount of gas supplied may be appropriately determined in consideration of various parameters such as the area of ​​the concrete 144 to be cured, the volume of the space 156, the cover thickness of the concrete 144 (the distance between the floor reinforcing bar unit and the surface of the concrete 144), the concentration of carbon dioxide in the gas, the temperature during curing, and the characteristics of the concrete to be placed. For example, the concentration of carbon dioxide in the space 156 may be appropriately set within a range of 1 volume % or more and 100 volume % or less. The pressure in the 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 in the space 156 is 1 atmosphere or more and 1.3 atmospheres or less. 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 engages with the ring. A concentration meter 164 or a hygrometer 166 for monitoring the carbon dioxide concentration and humidity in space 156, respectively, may be attached to opening 154 (FIGS. 5(A) and 6(A)). Although not shown, a thermometer for monitoring the temperature of space 156 may also be disposed. These detectors such as concentration meter 164, hygrometer 166, and thermometer may have a communication function. 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 to a control device or a communication terminal described later by wireless or wired communication.

[0039] (3) Water supply During curing, a water supply source 174 may be provided to supply water into the space 156 through 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 water to be supplied. Alternatively, a gas containing carbon dioxide 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. As with the amount of carbon dioxide to be supplied, the amount of water to be supplied is determined taking into consideration the above-mentioned parameters. By supplying water to the space 156, the humidity of the space 156 can be controlled. 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 required for hydration of the cement due to evaporation can be prevented.

[0040] During curing, the curing environment may be monitored using the various detectors described above. For example, a concentration meter 164 and a humidity meter 166 are used to periodically measure the carbon dioxide concentration and humidity in the space 156. The measurement results may be transmitted to a control device connected to the concentration meter 164 and the humidity meter 166 by wire or wirelessly, or to a mobile communication terminal such as a smartphone or tablet. 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. Also, the carbon dioxide supply source 170 may be equipped with a communication function and may 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 at, for example, 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 device or a cooling device mounted on the water supply source 174. These operations may also be performed manually or automatically. In addition, the water supply source 174 may be equipped with a communication function and the water supply source 174 may 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 exhausted outside structure 100.

[0044] In the above-mentioned 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 in the sealed space 156. Therefore, the carbon dioxide supplied to the space 156 comes into contact with the concrete 144 efficiently, and the leakage of carbon dioxide is prevented, ensuring high safety during the curing work.

[0045] Cement, which is a raw material of 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 suppressing global warming.

[0046] Known methods for fixing 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 pouring concrete at the site where the structure is to be constructed.

[0047] In contrast, in a curing method according to one of the present embodiments, not only can carbon dioxide be fixed in concrete poured at the construction site of the structure 100, but concrete of any size and area can be cured 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 at approximately 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 the concrete increases by about 8% to 10%. In addition, 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 large amount of carbon dioxide, approximately 60 tons, can be fixed for a 100m x 100m concrete floor slab produced as a concrete floor. Furthermore, the inventors' calculations show that depending on the materials used in the concrete, a maximum of approximately 120 kg of carbon dioxide can be fixed 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 112 and the hoops 114 hardens, part or all of the formwork 140 is removed. Then, the surface of the concrete 144 constituting 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), a sealing member 160 may be provided to surround the upper and lower parts of the column, and the flexible sheet 150 may be fixed using the sealing member 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 or ceiling (the back surface of floor slab concrete or deck plate 132), concrete 144 constituting part of the beam, or concrete column, or may be fixed to the remaining formwork 140. Fixing may be performed using adhesive tape, adhesive, nails, or the like.

[0049] Thereafter, 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, and the column concrete can effectively absorb the carbon dioxide as calcium carbonate. As in the curing of floor slab concrete, water may be supplied to the space using another opening 154. In addition, 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 supply amount of gas containing carbon dioxide and water, and the temperature of the water may be appropriately controlled. Since the other configurations are the same as those of the curing of floor slab concrete, detailed explanations will be omitted.

[0050] 4.Curing the ceiling concrete The ceiling concrete can be cured in the same manner. That is, a formwork is provided on the ceiling of the building structure 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, a part or all of the formwork is removed. Then, the ceiling concrete is covered with a flexible sheet 150 to seal the surface of the ceiling concrete. The surface of the ceiling concrete may be sealed by fixing the flexible sheet 150 to the ceiling concrete, columns, beams, or walls using an adhesive tape, or by fixing the flexible sheet 150 to the remaining formwork. Alternatively, as shown in FIG. 13, the ceiling concrete may be sealed by fixing a sealing member 160 to the beams, columns, walls, or ceiling concrete, and using this sealing member 160 to fix the flexible sheet 150.

[0051] Thereafter, 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 in the curing of the floor slab concrete, water may be supplied to the space using another opening 154. Also, during the curing, 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, and the supply amount of gas containing carbon dioxide and water, and the temperature of the water may be appropriately controlled. Since the other configurations are the same as those of the floor slab concrete, detailed explanations will be omitted.

[0052] 5.Curing wall concrete The curing of the wall concrete can be performed in the same manner. That is, a formwork is provided to sandwich the reinforcing bar units that constitute the wall of the building 100, and concrete 144 is poured into the formwork to form the wall concrete. After the concrete 144 hardens, a part or all of the formwork is removed. Then, the wall concrete is covered with a flexible sheet 150 to seal the surface of the wall concrete. The surface of the wall concrete may be sealed by fixing the flexible sheet 150 to the wall concrete, beams, ceiling, or floor slab concrete using an adhesive tape, or by fixing the flexible sheet 150 to the remaining formwork. Alternatively, as shown in FIG. 14, the wall concrete may be sealed by fixing a sealing member 160 to the beam, column, ceiling, or wall concrete, and using the 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 in the curing of floor slab concrete, water may be supplied to the space using another opening 154. Also, during curing, 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, and the supply amount of gas containing carbon dioxide and water, and the temperature of the water may be appropriately controlled. Other configurations are the same as those in the curing of floor slab concrete, so a detailed description will be omitted.

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

[0055] 6. Footing curing This curing method is also applicable to the curing of mass concrete such as footings. When applying to footings, first, as shown in Fig. 15(A), a plurality of reinforcing bars are combined to prepare a reinforcing bar unit 182 that will be the basic framework of a footing 180. There are no restrictions on the number and arrangement of the plurality of reinforcing bars, nor on the shape of the reinforcing bar unit 182, and they can be set arbitrarily according to the size, shape, and required strength of the footing 180. The reinforcing bar unit 182 may be installed directly on the ground, or on a slab concrete (waste concrete) 184.

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

[0057] Thereafter, for example, a flexible sheet 150 is placed on the surface of the formwork 140 or the concrete 144 (FIG. 16(A)). Alternatively, as shown in FIG. 16(B), a part or all of the formwork 140 is removed, and the flexible sheet 150 is placed so as to cover the top and sides of the concrete 144. The flexible sheet 150 is then fixed 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 slab concrete 184, or the remaining formwork 140. Alternatively, as shown in FIG. 16(B), a sealing member 160 may be fixed to the ground, the slab concrete 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, 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 performed. 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 in the curing of floor slab concrete, water may be supplied to the above space through another opening 154. In addition, 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 supply amounts of gas containing carbon dioxide and water, and the temperature of the water may be appropriately controlled.

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

[0060] The above-described embodiments of the present invention may be combined as appropriate as long as they are not mutually inconsistent. Any embodiment in which a person skilled in the art appropriately adds or deletes components or modifies the design based on each embodiment is also included in 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 respective embodiments described above, those which are clear from the description in this specification or which 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 bar, 120: Beam reinforcing bar unit, 122: Steel frame, 124: Beam main bar, 126: Horizontal reinforcement bar, 130: Floor reinforcing bar unit, 132: Deck plate, 134: Hanging material, 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: protective window, 164: concentration meter, 166: humidity meter, 170: carbon dioxide supply source, 172: carbon dioxide line, 174: water supply source, 176: water line, 180: footing, 182: reinforcing bar unit, 184: slab concrete

Claims

1. At the site where the structure is being constructed, Covering the surface of the concrete constituting the structure with a curing material; sealing the space between the surface and the covering member; and supplying a gas comprising carbon dioxide to the space; The carbon dioxide concentration of the gas is greater 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 periphery; 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 method for curing concrete 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 of curing concrete according to claim 2, wherein a plurality of said openings are provided in said flexible sheet, and said gas is supplied to said plurality of openings via a branched carbon dioxide line.

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 said first rim and said second rim has a groove and the other has a protrusion that mates with said 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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