JP2023128513A - Method for fixing carbon dioxide - Google Patents

Abstract

To provide a method for fixing carbon dioxide using a block-like concrete that does not contain a steel rod.SOLUTION: A method for fixing carbon dioxide includes: preparing a ready-mixed concrete; compacting the ready-mixed concrete; and curing the compacted ready-mixed concrete in a gas containing carbon dioxide at a concentration of 400 ppm or higher and 100% or lower. The compacted ready-mixed concrete may be cured in a flexible bag or a container having fixed capacity. The fixing method may further include: covering the compacted ready-mixed concrete with a flexible sheet; and introducing a gas containing carbon dioxide into the space covered with the sheet.SELECTED DRAWING: Figure 1

Description

One embodiment of the present invention relates to a method of fixing carbon dioxide using concrete.

A known method for fixing large amounts of carbon dioxide is to bring concrete into contact with a gas containing carbon dioxide. In this method, concrete obtained by curing ready-mix concrete is placed in a curing tank, and a gas containing carbon dioxide at a higher concentration than the atmosphere is introduced into the curing tank (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2009-149456

An object of one embodiment of the present invention is to provide a method for fixing carbon dioxide using block-shaped concrete (hereinafter referred to as concrete block) that does not contain reinforcing steel. Alternatively, an object of one of the embodiments of the present invention is to provide a method for manufacturing a concrete block.

One embodiment of the present invention is a method for fixing carbon dioxide. The fixing method includes preparing ready-mixed concrete, molding the ready-mixed concrete, and curing the molded ready-mixed concrete in a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less.

One embodiment of the present invention is a method for fixing carbon dioxide. This fixing method includes placing a hardened concrete block in a flexible bag, and supplying a gas containing carbon dioxide to the bag at a concentration of 400 ppm or more and 100% or less.

One embodiment of the present invention is a method for fixing carbon dioxide. This fixing method includes covering a hardened concrete block with a flexible sheet, and supplying a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less into a space covered with the sheet.

One embodiment of the present invention is a method for manufacturing concrete blocks. The manufacturing method includes preparing ready-mixed concrete, molding the ready-mixed concrete, and curing the molded ready-mixed concrete in a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less.

1 is a flowchart showing a method for fixing carbon dioxide, which is one embodiment of the present invention. 1 is a schematic perspective view of a container applicable to a carbon dioxide fixation method that is one of the embodiments of the present invention. FIG. 1 is a schematic top view of a bag applicable to the method of fixing carbon dioxide, which is one of the embodiments of the present invention. FIG. 1 is a schematic end view of a bag applicable to the carbon dioxide fixation method that is one of the embodiments of the present invention. FIG. 2 is a schematic end view of a part of a bag applicable to the method of fixing carbon dioxide, which is one of the embodiments of the present invention. FIG. 2 is a schematic end view of a part of a bag applicable to the method of fixing carbon dioxide, which is one of the embodiments of the present invention. 1 is a schematic perspective view showing a method for fixing carbon dioxide, which is one embodiment of the present invention. 1 is a schematic perspective view showing a method for fixing carbon dioxide, which is one embodiment of the present invention. FIG. 1 is a schematic top view showing a method for fixing carbon dioxide, which is one of the embodiments of the present invention. FIG. 1 is a schematic end view showing a method for fixing carbon dioxide, which is one of the embodiments of the present invention. 1 is a schematic perspective view showing a method for fixing carbon dioxide, which is one embodiment of the present invention. 1 is a schematic perspective view showing a method for fixing carbon dioxide, which is one embodiment of the present invention. FIG. 1 is a schematic end view showing a method for fixing carbon dioxide, which is one of the embodiments of the present invention. FIG. 1 is a schematic top view showing a method for fixing carbon dioxide, which is one of the embodiments of the present invention. FIG. 1 is a schematic end view showing a method for fixing carbon dioxide, which is one of the embodiments of the present invention.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in various forms without departing from the scope thereof, and should not be construed as being limited to the contents described in the embodiments exemplified below.

In order to make the explanation more clear, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but these are merely examples and do not limit the interpretation of the present invention. It's not something you do. In this specification and each figure, the same reference numerals may be given to elements having the same functions as those explained in relation to the previous figures, and redundant explanation may be omitted.

In this specification, concrete refers to a hardened product that does not exhibit fluidity and is obtained by hardening cement hydrate, which is produced by reacting cement, one of the raw materials, with water. Therefore, mortar that does not contain aggregate is also included in the category of concrete. Concrete may include fine aggregate with a diameter of 5 mm or less and coarse aggregate with a diameter of more than 5 mm (for example, greater than 5 mm and less than 20 mm, or greater than 5 mm and less than 20 mm). On the other hand, concrete before hardening, that is, a mixture containing cement and water and having fluidity without being completely hardened, is called ready-mixed concrete (also called ready-mixed concrete). In addition to cement, water, and aggregate, ready-mixed concrete may also contain additives such as an AE agent (air dispersant), a fluidizer, and a thickener.

As used herein, "curing" refers to a process for curing ready-mixed concrete, and by curing ready-mixed concrete, hardened ready-mixed concrete, ie, concrete is formed.

<First embodiment>
Hereinafter, a method for fixing carbon dioxide according to one embodiment of the present invention will be described. As can be understood from the following explanation, in this carbon dioxide fixation method, carbon dioxide is used during curing of the molded ready-mix concrete, which not only fixes carbon dioxide but also increases the strength of the resulting concrete. can. Therefore, this method of fixing carbon dioxide can also be referred to as a method of manufacturing concrete blocks, and therefore, embodiments of the present invention also include methods of manufacturing concrete blocks.

FIG. 1 shows a flowchart of a method for fixing carbon dioxide according to one embodiment of the present invention. As shown in FIG. 1, in this fixing method, ready-mixed concrete is first prepared and molded. Thereafter, the ready-mixed concrete is cured (primary curing) and then cured in a gas containing carbon dioxide (secondary curing) to obtain a concrete block in which carbon dioxide is fixed.

1. Preparation of ready-mixed concrete Ready-mixed concrete is prepared by mixing cement, aggregate, water, and additives. There are no restrictions on the type of cement; ordinary Portland cement, white Portland cement containing iron oxide, alumina cement containing alumina, blast furnace cement containing blast furnace slag, a by-product of the steel manufacturing process, and a by-product of lime ash combustion. Fly ash cement to which fly ash cement is added, ecocement containing waste such as incineration ash and sludge, etc. can be used. As the aggregate, sand, gravel, pumice, blast furnace slag, etc. may be used, or recycled crushed stone obtained by crushing discarded concrete may be used. The weight ratio of cement and aggregate may also be appropriately set in consideration of the properties required of the resulting concrete block; for example, the weight of aggregate may be 3 times or more and 10 times or less the weight of cement. There are no restrictions on the water/cement ratio, but it may be selected from a range of 10% to 100%. As the additive, the various additives mentioned above may be used as appropriate depending on the use of the concrete block.

Furthermore, fly ash, slag, ash such as biomass ash or incineration ash, silica fume, etc. may be added as an admixture together with or in place of the aggregate. The amount of the admixture may be determined as appropriate, but it may be adjusted so that the water binder ratio (W/B) is 10% or more and 100% or less. Here, the binder refers to cement and admixture, and the water binder ratio is the mass of water to the total mass of cement and admixture.

Through the above steps, ready-mixed concrete having fluidity is obtained. However, the ready-mixed concrete obtained here does not need to have high fluidity and may be in a dry state. In other words, the ready-mixed concrete obtained through the steps up to this point has a large amount of voids between each component such as cement, aggregate, and admixtures, and is in a solid state that easily deforms when external forces are applied. It is sufficient if it has the following.

2. Forming Forming is performed by filling ready-mixed concrete into a mold and applying pressure. The pressure during pressurization may be selected, for example, from a range of 1 MPa or more and 10 MPa or less. At this time, vibration may be applied to remove air mixed in the mold so that the entire inside of the mold is filled with ready-mixed concrete at a high density. Note that no reinforcing bars are placed inside the mold.

3. Primary curing After this, primary curing is performed. Primary curing is a process in which the molded ready-mix concrete maintains its fluidity and hardens to a state where it can stand on its own. Here, the self-supporting state refers to a state in which the three-dimensional shape created by molding can be maintained without being easily deformed even if force is applied from the outside. Therefore, during the primary curing, the ready-mixed concrete does not completely harden, giving a concrete block before hardening.

The primary curing may be performed with ready-mixed concrete filled in a mold, but although ready-mixed concrete immediately after forming may deform when external force is applied, if there is no external force other than gravity, the shape will change. If the condition can be maintained, it may be carried out after demolding. The primary curing may be performed indoors or outdoors. Alternatively, curing may be performed in a dedicated curing room. The temperature of the primary curing may be room temperature, but it may also be carried out at a high temperature higher than room temperature. Moreover, in the primary curing, high-temperature steam may be sprayed onto the ready-mix concrete. When primary curing is performed in a mold, ready-mix concrete is removed from the mold during or after primary curing.

4. Secondary curing The ready-mixed concrete removed from the mold is then subjected to secondary curing. In the secondary curing, the ready-mixed concrete made by the primary curing is cured in a gas containing carbon dioxide until it is completely cured. The secondary curing can be performed, for example, in a pressure-resistant container 100 having a fixed capacity as shown in FIG. The capacity of the container 100 may be determined based on the size and shape of the concrete block 160. Moreover, the container 100 may be configured to accommodate a plurality of concrete blocks 160. The container 100 has a main body 102 and a lid 104, and the container 100 is configured such that the inside can be sealed by the lid 104 and the main body 102. The main body 102 and the lid 104 may include, for example, metal such as iron, aluminum, or stainless steel, or resin. Although the container 100 shown in FIG. 2 has a main body 102 and a lid 104 separated from each other, the container 100 may be configured such that the main body 102 and the lid 104 are connected to each other and can be opened and closed using a hinge or the like.

The main body 102 or the lid 104 is provided with an exhaust pipe 114 connected to an exhaust device and an inlet 108 for filling gas containing carbon dioxide. Inlet 108 may be configured to be opened and closed by valve 106. Optionally, container 100 may include a pressure gauge 110 for measuring internal pressure. Pressure gauge 110 may be connected to lid 104 and, although not shown, may be connected to body 102 or inlet 108. Furthermore, the lid 104, the body 102, or the inlet 108 may be provided with a water injection pipe 112 for injecting water or steam. Although not shown, the container 100 may further include a hygrometer for measuring internal humidity, a densitometer for measuring carbon dioxide concentration, and the like.

Alternatively, as shown in the schematic end view (FIG. 3B) along the dashed line AA' in FIGS. It may also be carried out within the bag 120. Bag 120 may include a material that is transparent to visible light or may include a material that is opaque to visible light. For example, the bag 120 may include a polymer material with high gas barrier properties, such as polyethylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, or polyethylene-vinyl alcohol copolymer. Alternatively, mechanically strong polymers (e.g., engineering plastics) such as polyesters such as polyacetal, polyamide, polyimide, and polyethylene terephthalate, aromatic polycarbonates, polyphenylene ethers, polysulfones, polyethersulfones, polyphenylene sulfides, and polyether ketones. Bag 120 may be constructed using fibers. This fiber may be combined with glass fiber or carbon fiber. If the material constituting the bag 120 has high gas permeability, the inside and/or outside of the bag 120 may be coated with a metal film such as aluminum.

Bag 120 is open at least at one end so that one or more concrete blocks 160 can be inserted and removed. A zipper 122 may be provided at this open end to seal the inside of the bag 120. Furthermore, a cap structure 124 may be provided to replace the air inside the bag 120 with gas containing carbon dioxide and to seal the inside of the bag 120. The structure of the cap structure 124 may be arbitrarily determined, and any structure can be applied as long as it can open and seal the internal space of the bag 120. For example, as shown in a schematic end view (FIG. 4A) taken along the chain line BB' in FIG. 3A, the cap structure 124 may include a ring 126 attached to the bag 120 and a cap 130 that closes the ring 126. . The ring 126 may have a female threaded structure on its inner wall, and the cap 130 may also be a screw cap with a male threaded structure that engages the ring 126. This allows the opening 128 of the ring 126 to be closed by inserting or screwing a portion of the cap 130 into the ring 126.

Alternatively, as shown in FIGS. 5A and 5B, a plurality of concrete blocks 160 are placed on a pallet 140, covered with a flexible sheet 142, and subjected to secondary curing in the space covered by the sheet 142. You may do so. The pallet 140 may be made of concrete, metal such as iron or stainless steel, wood, or the like. On the other hand, the sheet 142 can include a material that can be used in the bag 120, and one or both sides of the sheet 142 can be coated with a metal film. The seat 142 may be provided with a cap structure 144 similar to the cap structure 124 described above.

The pallet 140 may be provided with a fixing mechanism for fixing the sheet 142 and the pallet 140 so that gas containing carbon dioxide does not leak from between the sheet 142 and the pallet 140. There are no restrictions on the fixing mechanism, and as shown in a schematic top view of a part of the end of the pallet 140 (FIG. 6A) and a schematic diagram of the end face along the chain line CC' (FIG. 6B), the pallet 140 is A provided groove and one or more rims 146 configured to engage the groove and surround the placed concrete block 160 may be employed as the fixing mechanism. The space covered by the sheet 142 is sealed by covering the concrete block 160 with the sheet 142 so that the groove of the pallet 140 and the sheet 142 overlap, and by sandwiching the ends of the sheet 142 between the groove and the rim 146.

Alternatively, as shown in FIGS. 7A and 7B, instead of the pallet 140, a frame 148 surrounding a plurality of concrete blocks 160 is arranged, and the concrete blocks 160 are covered with a sheet 142 so as to cover the concrete blocks 160 and the frame 148. Secondary curing may be performed in the space covered by 142. In this case, the concrete blocks 160 and the frame 148 may be placed directly on the ground, or the concrete blocks 160 and the frame 148 may be placed on the pallet 140. Like the pallet 140, the frame 148 may also be made of concrete, metal such as iron or stainless steel, wood, or resin. As shown in the schematic end view of frame 148 (FIG. 8), frame 148 may also be provided with grooves that engage rim 146. With this configuration, the sheet 142 can be sandwiched and fixed between the frame 148 and the rim 146, so that leakage of gas containing carbon dioxide can be suppressed.

The temperature of the secondary curing can also be set arbitrarily. For example, the temperature of the environment where the container 100 or the bag 120 is placed, or the temperature of the environment where the concrete block 160 covered with the sheet 142 is placed may be used. In this case, temperature control is not required in the secondary curing, and thereby the secondary curing can be performed at low cost. Alternatively, the concrete block 160 housed in the container 100 or the bag 120 may be placed indoors, and secondary curing may be performed at a temperature of 40° C. or higher and 60° C. or lower.

The concentration of carbon dioxide in the carbon dioxide-containing gas during secondary curing is higher than that of the atmosphere. More specifically, the carbon dioxide concentration is appropriately selected from 400 ppm or more and 100% or less. Gas containing carbon dioxide may be supplied from cylinders filled with carbon dioxide, or may be supplied from facilities that emit large amounts of carbon dioxide (chemical plants, garbage incineration facilities, thermal power plants) near the site where secondary curing is performed. , various other factories, etc.), the gas emitted by these facilities or purified carbon dioxide obtained by performing dedusting, desulfurization, denitrification, etc. on the exhaust gas is converted into carbon dioxide. It may also be used as a containing gas. In this case, these facilities act as a source of carbon dioxide-containing gas, reducing the cost of transporting carbon dioxide and preventing further emissions of carbon dioxide from transport.

Although not shown, a humidifier may be connected to the gas containing carbon dioxide, and water vapor may be added to adjust the humidity of the gas containing carbon dioxide as appropriate.

When using the container 100 having a fixed capacity, the gas containing carbon dioxide may be introduced using the inlet 108. For example, after opening the valve 106, an exhaust device such as a rotary pump (not shown) is connected to the inlet 108. After that, the container 100 is evacuated (degassed) so that the pressure inside the container 100 becomes, for example, 10 Pa or more and 1000 Pa. The evacuation time is also arbitrary, and may be appropriately set within the range of 1 minute or more and 1 day or less. Thereafter, gas containing carbon dioxide is introduced and valve 106 is closed. The pressure of the gas containing carbon dioxide in the container 100 is preferably 1 atm (0.10 MPa) or more, more preferably 0.20 MPa or more and 2 MPa or less, or more preferably 0.5 MPa or more and 1 MPa or less. When a pressure gauge 110 is provided, the pressure inside the container 100 obtained from the pressure gauge may be monitored, and gas containing carbon dioxide may be intermittently supplied to maintain a constant pressure.

If a bag 120 is used, one or more concrete blocks 160 are placed in the bag 120 and the zipper 122 is closed. Thereafter, the cap 130 of the cap structure 124 is removed, and an exhaust device is connected to the opening 128 to exhaust the inside. Thereafter, a supply pipe 132 for supplying gas containing carbon dioxide is connected to the opening 128 (see FIG. 4B), the gas containing carbon dioxide is introduced into the bag 120, and the cap 130 is closed. The pressure of the gas containing carbon dioxide is appropriately selected from the range mentioned above.

In addition, when using the bag 120 without the chuck 122 or the cap structure 124, the open end is narrowed and an exhaust device is connected to the narrowed open end to exhaust the inside. Thereafter, gas containing carbon dioxide may be introduced from the open ends, and the open ends may be tied to seal the inside. In this case, the open end of the supply pipe 132 for supplying gas containing carbon dioxide may be maintained in a fixed state, and the gas containing carbon dioxide may be supplied intermittently or constantly.

When using the sheet 142, the pallet 140 or frame 148 is first placed. Thereafter, a plurality of concrete blocks 160 are placed on the pallet 140, or a plurality of concrete blocks 160 are placed so as to be surrounded by the frame 148. Sheet 142 is then covered over concrete block 160 and rim 146 is used to secure sheet 142 to pallet 140 or frame 148. Thereafter, the space covered by the sheet 142 is evacuated using the cap structure 144, and gas containing carbon dioxide is supplied to this space. The gas containing carbon dioxide may be supplied constantly or intermittently.

Note that when a fixing mechanism for fixing the sheet 142 is not used, the sheet 142 is fixed using a heavy object such as a sandbag or a metal rod, and the sheet 142 is fixed between the sheet 142 and the pallet 140 or between the sheet 142 and the frame 148. A supply pipe 132 may be inserted between them to supply gas containing carbon dioxide constantly or intermittently.

The time for secondary curing may be determined as appropriate depending on the temperature, the humidity and carbon dioxide concentration of the gas containing carbon dioxide, the size of the concrete block, the water/cement ratio, etc. For example, 1 day or more and 1 month or less, What is necessary is just to select from the range of 10 days or more. After the secondary curing is completed, the supplied gas containing carbon dioxide may be sucked in with a pump, collected into a container such as a tank, and used again for the secondary curing.

Through the above steps, it is possible to fix carbon dioxide to the concrete block 160, and to provide a concrete block 160 that does not contain reinforcing bars and in which carbon dioxide is fixed. Since this method does not require a dedicated curing tank for curing the concrete blocks 160, it is possible to significantly reduce the cost required for constructing equipment for performing secondary curing. Therefore, a large amount of carbon dioxide can be fixed at lower cost. In fact, as described in the examples, this fixation method allows about 40 to 50 times more carbon dioxide to be fixed than when carbon dioxide is fixed in the atmosphere. Furthermore, especially when using the sheet 142 or bag 120, since the sheet 142 or bag 120 is flexible, this fixing method can be applied even if the size and shape of the concrete block 160 varies. can. Therefore, concrete blocks 160 having various sizes and shapes can be manufactured, and carbon dioxide can be fixed without being restricted by the size or shape of the concrete blocks 160.

Furthermore, since the concrete block 160 manufactured by this method fixes a large amount of carbon dioxide, it is possible to provide a concrete block with high strength. As described in the examples, by applying this method, it is possible to manufacture a concrete block 160 whose compressive strength is increased by several percent to more than ten percent compared to the case of secondary curing in the atmosphere. .

<Second embodiment>
In this embodiment, a method of fixing carbon dioxide to a concrete block obtained by curing ready-mixed concrete after molding will be described. Descriptions of configurations that are the same or similar to those in the first embodiment may be omitted.

1. Preparation of Concrete Block In this embodiment, ready-mixed concrete is first filled into a mold and pressurized, and then temporarily cured and taken out from the mold. The temporarily cured ready-mix concrete is subjected to secondary curing and hardening in the atmosphere at room temperature or at a temperature of 40° C. or more and 60° C. or less to obtain a concrete block. The steps up to this point can be performed by appropriately applying known methods, so detailed explanations will be omitted.

2. Carbon dioxide fixation The concrete blocks used for carbon dioxide fixation may be concrete blocks that have not yet been laid, or may be concrete blocks that have already been laid on roads, slopes, cliffs, etc. Carbon dioxide fixation may be performed in the same manner as the secondary curing described in the first embodiment. Specifically, one or more concrete blocks are housed in the fixed capacity container 100 or flexible bag 120 described in the first embodiment (see FIGS. 2, 3A, and 3B). When using concrete blocks that have been laid, the concrete blocks that have been laid may be peeled off and placed in the container 100 or the bag 120. Thereafter, as described in the first embodiment, the inside of the container 100 or bag 120 is evacuated, and gas containing carbon dioxide is further injected into the container 100 or bag 120. The gas containing carbon dioxide may be injected once, intermittently multiple times, or constantly.

Alternatively, a plurality of concrete blocks are placed on a pallet 140 or surrounded by a frame 148 (see FIGS. 5A, 5B, 7A, and 7B). Thereafter, a plurality of concrete blocks are covered using the sheet 142, the space covered by the concrete blocks is evacuated, and gas containing carbon dioxide is supplied to this space. The gas containing carbon dioxide may be supplied once, intermittently multiple times, or constantly.

Through the process described above, the concrete blocks are brought into contact with a gas containing carbon dioxide at a high concentration. Conditions at this time, such as temperature, humidity, contact time, etc., may be selected from the same conditions as those described in the first embodiment.

In this fixing method, a gas containing carbon dioxide may be brought into direct contact with the laid concrete blocks. In this case, for example, as shown in FIG. 9A, a frame 148 in which a groove is formed is arranged to surround a plurality of laid concrete blocks 162. After that, as shown in the schematic diagram of the end surface along the chain line DD' in FIG. 9A (FIG. 9B), the sheet 142 is placed over the concrete block 162 in the laid state, and the sheet 142 is attached to the frame 148. It is fixed using the rim 146. Furthermore, the space covered by the sheet 142 may be evacuated using the cap structure 144, and then gas containing carbon dioxide may be introduced into this space. Note that when the concrete blocks are laid parallel to a substantially horizontal surface, the sheet 142 may be fixed with a heavy object such as a sandbag without using a fixing mechanism.

With this method, it is not necessary to collect and re-lay the concrete blocks that have been laid, so carbon dioxide can be fixed in a shorter time. In addition, when a concrete block expands due to the formation of calcium carbonate due to the reaction between calcium hydroxide and carbon dioxide contained in the concrete block, it becomes difficult to reproduce the initial state before recovery of the concrete block. Since the initial state can be easily maintained and the frictional force between the concrete blocks can be increased, the concrete blocks can be more firmly joined together.

In this example, an example will be described in which carbon dioxide is fixed in a hardened concrete block using the container 100.

1. Preparation of concrete blocks 350 kg of ordinary Portland cement, ¹⁵⁰ kg of water, 100 kg of ground blast furnace slag powder, 100 kg of fine aggregate (particle size of 5 mm or less), 333 kg of coarse aggregate (particle size of 5 mm to 10 mm), and Ready-mixed concrete was prepared by mixing 20 kg of admixture. At this time, the water-cement ratio was 43%, and the water-binder ratio was 33%. The obtained ready-mixed concrete was filled into a 100 mm x 200 mm x 60 mm iron mold, and was pressurized and compressed from above the mold using a 100 mm x 200 mm metal jig at a pressure of 8 MPa. Thereafter, the ready-mixed concrete was taken out of the mold and cured for 7 days in a high-temperature, constant-humidity room at a temperature of 20° C. and a humidity of 50% to produce a concrete block. A concrete block at this stage is used as a comparative example.

The concrete block was placed in a cylindrical pressure-resistant container with a diameter of 400 mm and a height of 600 mm. After the inside was degassed for 3 hours using a vacuum pump, 100% carbon dioxide was introduced for 24 hours so as to maintain the pressure inside the container at 0.5 MPa, thereby producing the concrete block of the example. The n number of each of the comparative example and the example was 5.

2. Results When the masses of the concrete blocks of the comparative example and the example were compared, it was confirmed that the latter was 3% to 4% higher than the former. Calcium carbonate in the concrete blocks of Comparative Examples and Examples was quantified using a thermogravimetric thermal analyzer (TG-DTA manufactured by Rigaku Corporation), and the amount of carbon dioxide fixed was calculated from the amount of calcium carbonate obtained. , in the comparative example, it was 2 kg/m ³ to 5 kg/m ³ , whereas in the example, it was 80 kg/m ³ to 100 kg/m ³ . Furthermore, when the concrete block of the example was cut and a 1% ethanol solution of phenolphthalein was sprayed on the cross section of the concrete block as an indicator, coloration of the indicator was confirmed on the entire cross section. From this, it was found that in the example, carbon dioxide was fixed throughout almost the entire concrete block.

As a result of measuring the compressive strength according to the regulations of JISA1108, the compressive strengths of the concrete blocks of the comparative example and the example were 24 N/mm ² and 28 N/mm ² , respectively. From this, it was confirmed that a concrete block with high compressive strength can be manufactured by the method for manufacturing a concrete block, which is one of the embodiments of the present invention.

The embodiments described above as embodiments of the present invention can be implemented in appropriate combinations as long as they do not contradict each other. Additions, deletions, or design changes to components based on each embodiment by those skilled in the art are also included in the scope of the present invention, as long as they have the gist of the present invention.

Even if there are other effects that are different from those brought about by each of the embodiments described above, those that are obvious from the description of this specification or that can be easily predicted by a person skilled in the art are naturally included in the present invention. It is understood that this is brought about by

100: Container, 102: Main body, 104: Lid, 106: Valve, 108: Inlet, 110: Pressure gauge, 112: Water injection pipe, 114: Exhaust pipe, 120: Bag, 122: Chuck, 124: Cap structure, 126: Ring, 128: Opening, 130: Cap, 132: Supply pipe, 140: Pallet, 142: Sheet, 144: Cap structure, 146: Rim, 148: Frame, 160: Concrete block, 162: Concrete block

Claims (9)

preparing ready-mixed concrete;
A method for fixing carbon dioxide, comprising: forming the ready-mixed concrete; and curing the formed ready-mixed concrete in a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less. 2. The fixing method according to claim 1, wherein the curing is performed in a flexible bag or a fixed capacity container. The fixing method according to claim 1, further comprising: covering the molded ready-mix concrete with a flexible sheet; and introducing the gas into a space covered by the sheet. 4. The fixing of claim 3, further comprising: placing the molded ready-mixed concrete on a pallet before covering with the sheet; and securing the sheet to the pallet to seal the space. Method. further comprising: arranging a fixed frame surrounding the molded ready-mix concrete; and fixing the sheet to the fixed frame to seal the space;
4. The fixation method according to claim 3, wherein the fixation frame has a first frame with a groove and a second frame that engages with the groove. A method for fixing carbon dioxide, comprising: placing a hardened concrete block in a flexible bag; and supplying a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less to the bag. A method for fixing carbon dioxide, comprising: covering a hardened concrete block with a flexible sheet; and supplying a gas containing carbon dioxide at a concentration of 400 ppm or more and 100% or less into a space covered with the sheet. further comprising: arranging a fixed frame surrounding the concrete block before covering with the sheet; and securing the sheet to the fixed frame;
8. The fixation method according to claim 7, wherein the fixation frame has a first frame having a groove and a second frame that engages the groove. The fixing method according to claim 7 or 8, wherein the concrete block is a concrete block laid outdoors.

Images