Method for manufacturing carbon dioxide-fixed concrete
By supplying γ-C2S and dry ice to fresh concrete at the casting site and allowing post-placement fixation, the method addresses temporal and spatial constraints, increasing carbon dioxide fixation capacity and reducing construction risks and costs.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KAJIMA CORP
- Filing Date
- 2021-11-30
- Publication Date
- 2026-06-17
Smart Images
Figure 0007874954000003 
Figure 0007874954000004 
Figure 0007874954000005
Abstract
Description
[Technical Field]
[0001] This invention relates to a method for producing carbon dioxide-fixed concrete. [Background technology]
[0002] The cement used in concrete emits large amounts of carbon dioxide (CO2) during manufacturing due to the decarbonization of the raw materials and the fuel used in firing. In light of the growing concern over climate change in recent years, there is a demand for a significant reduction in carbon dioxide emissions during concrete production.
[0003] One method for reducing carbon dioxide emissions is the widespread use of mixed cement, which is made by mixing granulated blast furnace slag (hereinafter simply referred to as blast furnace slag powder) with cement. However, increasing the amount of blast furnace slag powder slows down hardening, lengthening the period until demolding, and requiring long periods of wet curing to obtain sufficient strength. Therefore, challenges remain in terms of construction period and cost.
[0004] Furthermore, Patent Document 1 describes a method for carbonizing a concrete mixture containing cement by supplying carbon dioxide to the mixture, wherein the carbon dioxide is supplied within 3 minutes of the start of mixing the concrete mixture, and the carbon dioxide supply time is 10 seconds to 4 minutes. In the method of Patent Document 1, the timing of carbon dioxide supply is immediately after the start of mixing the concrete mixture. Also, the carbonation time of the concrete mixture is short. Therefore, in the method of Patent Document 1, there are time constraints on the carbonation of the concrete mixture, and the amount of carbon dioxide that can be carbonized is small. Moreover, due to the time constraints on carbonation, it is necessary to perform the carbonation of the concrete mixture at the place where the mixing of the concrete mixture is started, so there are also location constraints on the carbonation of the concrete mixture. [Prior art documents] [Patent Documents]
[0005] [Patent Document 1] International Publication No. 2016 / 082030 [Overview of the project] [Problems that the invention aims to solve]
[0006] The object of the present invention is to provide a method for manufacturing carbon dioxide-fixed concrete that suppresses the temporal and spatial constraints of carbon dioxide fixation and increases the amount of carbon dioxide that can be fixed, compared to conventional methods. [Means for solving the problem]
[0007] [1] A method for manufacturing carbon dioxide-immobilized concrete in which a predetermined amount of carbon dioxide is immobilized in concrete, comprising: a fresh concrete manufacturing step for manufacturing fresh concrete; a pre-casting carbon dioxide-immobilization step for supplying γ-C2S and dry ice together to the fresh concrete manufactured in the fresh concrete manufacturing step at a casting site and stirring to obtain carbon dioxide-immobilized fresh concrete in which carbon dioxide is immobilized in the fresh concrete; and a post-casting concrete hardening step for casting and hardening the carbon dioxide-immobilized fresh concrete obtained in the pre-casting carbon dioxide-immobilization step to obtain carbon dioxide-immobilized concrete. [2] The method for producing carbon dioxide-fixed concrete according to [1], wherein in the pre-casting carbon dioxide fixation step, a carbon dioxide fixation agent composed of water-soluble materials containing γ-C2S and dry ice is supplied to the fresh concrete. [3] The method for manufacturing carbon dioxide-fixed concrete according to [1] or [2] above, wherein in the carbon dioxide-fixing step before concrete placement, the supply ratio of γ-C2S to dry ice supplied to the fresh concrete is 5 to 70 parts by mass of dry ice per 100 parts by mass of γ-C2S. [4] In the carbon dioxide fixation process before concrete placement, the amount of γ-C2S supplied to the fresh concrete is: 3A method for manufacturing carbon dioxide-fixed concrete as described in any one of the above [1] to [3], wherein the amount per unit is between 1 kg and 100 kg. [5] The carbon dioxide-fixed concrete is the carbon dioxide-fixed concrete 1 m 3 A method for producing carbon dioxide-fixed concrete as described in any one of the above [1] to [4], wherein each portion contains 0.1 kg to 50 kg of carbon dioxide derived from calcium carbonate. [6] The method for producing carbon dioxide-fixed concrete according to any one of [1] to [4] above, wherein the pre-placement carbon dioxide fixation step is to supply γ-C2S and dry ice to the fresh concrete stored in the agitator vehicle. [7] The method for manufacturing carbon dioxide-fixed concrete according to [6] above, wherein the pre-casting carbon dioxide fixation step is to supply γ-C2S and dry ice from outside the agitator vehicle. [8] The carbon dioxide immobilization step before concrete placement is a method for producing carbon dioxide immobilized concrete according to [6] or [7] above, wherein one end of a carbon dioxide immobilization agent supply member is inserted into the rotating drum of the agitator vehicle from the input port of the agitator vehicle, and the other end is positioned outside the agitator vehicle and higher than the one end; the carbon dioxide immobilization agent is transferred from a carbon dioxide immobilization agent storage member containing a plurality of carbon dioxide immobilization agents containing powdered γ-C2S and dry ice with a particle size of 50 mm or less to the other end of the carbon dioxide immobilization agent supply member; the carbon dioxide immobilization agent is moved toward the one end of the carbon dioxide immobilization agent supply member to supply the carbon dioxide immobilization agent to the fresh concrete stored in the rotating drum of the agitator vehicle. [9] The carbon dioxide-fixed concrete is the carbon dioxide-fixed concrete 1 m 3 A method for producing carbon dioxide-fixed concrete as described in any one of [6] to [8] above, wherein each portion contains 2 kg to 10 kg of carbon dioxide derived from calcium carbonate. [Effects of the Invention]
[0008] According to the present invention, it is possible to provide a method for manufacturing carbon dioxide-fixed concrete that suppresses the temporal and spatial constraints of carbon dioxide fixation compared to conventional methods, and increases the amount of carbon dioxide that can be fixed. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 is a flowchart showing an example of a method for manufacturing carbon dioxide-fixed concrete according to an embodiment. [Figure 2] Figure 2 is a graph showing the relationship between the amount of carbon dioxide fixed in the carbon dioxide-fixed fresh concrete and the carbon dioxide supply time during the carbon dioxide fixation process before concrete placement. [Figure 3] Figure 3 is a schematic diagram showing an example of a method for supplying carbon dioxide fixation agent in the carbon dioxide fixation process before concrete placement. [Figure 4] Figure 4 is a schematic diagram showing another example of a method for supplying carbon dioxide fixation agent in the pre-casting carbon dioxide fixation process. [Figure 5] Figure 5 is a schematic diagram showing an example of the main components of an agitator vehicle used in the carbon dioxide-fixed concrete manufacturing method of the embodiment. [Figure 6] Figure 6 is a schematic diagram showing an example of a carbon dioxide immobilization process before concrete placement using an agitator vehicle. [Modes for carrying out the invention]
[0010] The following will provide a detailed explanation based on the embodiments.
[0011] The method for producing carbon dioxide-fixed concrete according to the present invention is a method for producing carbon dioxide-fixed concrete in which a predetermined amount of carbon dioxide is fixed in the concrete, and includes a fresh concrete production process for producing fresh concrete, and at the placing site, γ-C2S and dry ice are collectively supplied to and stirred in the fresh concrete produced in the fresh concrete production process to obtain carbon dioxide-fixed fresh concrete in which carbon dioxide is fixed in the fresh concrete. And a post-placement concrete curing process in which the carbon dioxide-fixed fresh concrete obtained in the pre-placement carbon dioxide fixation process is placed and cured to obtain carbon dioxide-fixed concrete.
[0012] FIG. 1 is a flowchart showing an example of a method for producing carbon dioxide-fixed concrete according to an embodiment. As shown in FIG. 1, the method for producing carbon dioxide-fixed concrete according to the embodiment includes a fresh concrete production process S10, a pre-placement carbon dioxide fixation process S20, and a post-placement concrete curing process S30. And by the method for producing carbon dioxide-fixed concrete, carbon dioxide-fixed concrete in which a predetermined amount of carbon dioxide is fixed in the concrete can be produced.
[0013] In the fresh concrete production process S10 that constitutes the method for producing carbon dioxide-fixed concrete, fresh concrete is produced. Fresh concrete is a fluidized material. Fresh concrete is a hydraulic composition and contains at least water (W), cement (C), and aggregates (fine aggregates (S) and coarse aggregates (G)).
[0014] The cement (C) contained in the fresh concrete is preferably Portland cement. Portland cement includes ordinary Portland cement (OPC), as well as types such as early strength, ultra-early strength, medium heat, and low heat sulfate-resistant, which are defined in JIS R 5210:2019. In fresh concrete, one or more of these various Portland cements can be used.
[0015] Alternatively, blast furnace cement (mixed cement) containing blast furnace slag powder (BFS) and cement material (C) may be used as cement (C). The blast furnace cement can be the one specified in JIS R 5211:2009.
[0016] The fine aggregate (S) contained in fresh concrete refers to the aggregate as defined in JIS A 5308, JIS A 5005, JIS A 5002, and JIS A 5011. Examples of fine aggregate (S) include crushed sand, sand, river sand, sea sand, crushed lime sand, recycled aggregate, lightweight aggregate, and heavy aggregate.
[0017] Coarse aggregate (G) in fresh concrete refers to aggregate as defined in JIS A 5308, JIS A 5005, JIS A 5002, and JIS A 5011. It is distinguished from fine aggregate (S) by particle size, specifically whether or not it passes through a 5mm sieve. In practice, aggregate that passes entirely through a 10mm sieve and more than 85% by weight through a 5mm sieve is classified as fine aggregate (S), while aggregate that remains in the 5mm sieve for more than 85% by weight is classified as coarse aggregate (G).
[0018] Fresh concrete may contain expansive agents and retarders in addition to the above components. Furthermore, it may contain other admixtures, etc., within the range that achieves the effects of the present invention. Examples of other admixtures include coal ash, fly ash, limestone powder, carbonate compounds such as light calcium carbonate with fixed atmospheric carbon dioxide, water-reducing agents, and fluidizing agents.
[0019] In fresh concrete, the water (W) / cement (C) ratio is preferably set appropriately within the range of 30% to 65%.
[0020] As shown in Figure 1, in the pre-placement carbon dioxide immobilization process S20, which is carried out after the fresh concrete manufacturing process S10, γ-C2S (γ-2CaO·SiO2; also called γ-belite) and dry ice are supplied together to the fresh concrete manufactured in the fresh concrete manufacturing process S10 and mixed to obtain carbon dioxide immobilized fresh concrete. The pre-placement carbon dioxide immobilization process S20 is carried out at the concrete placement site. The concrete placement site is the site where the carbon dioxide immobilized fresh concrete is placed.
[0021] Carbon dioxide-immobilized fresh concrete is fresh concrete in which carbon dioxide has been immobilized; it is essentially fresh concrete that has been carbonated. Carbon dioxide-immobilized fresh concrete is a fluidized material.
[0022] In the pre-placement carbon dioxide immobilization process S20, when γ-C2S and dry ice are supplied together to the fresh concrete, the moisture in the fresh concrete acts as a starting point, and the carbon dioxide generated by the sublimation of the dry ice reacts with the γ-C2S, thus immobilizing the carbon dioxide in the fresh concrete. This carbon dioxide immobilization reaction proceeds preferentially over the cement hydration reaction because γ-C2S does not hydrate and reacts only with carbon dioxide.
[0023] In the pre-placement carbon dioxide immobilization process S20, it is preferable to stir the fresh concrete when supplying γ-C2S and dry ice, from the viewpoint of rapidly increasing the amount of carbon dioxide immobilized in the fresh concrete. Stirring the fresh concrete when supplying γ-C2S and dry ice significantly increases the opportunity for contact between γ-C2S and carbon dioxide, starting with the moisture in the fresh concrete, allowing for an efficient reaction.
[0024] Furthermore, even after the supply of γ-C2S and dry ice has ended, carbon dioxide generated by the sublimation of dry ice remains around the carbon dioxide-immobilized fresh concrete. Therefore, even after the supply of γ-C2S and dry ice has ended, stirring the carbon dioxide-immobilized fresh concrete allows the γ-C2S present in the concrete to react efficiently with the carbon dioxide, further immobilizing carbon dioxide in the fresh concrete.
[0025] Furthermore, since dry ice is supplied to the fresh concrete and the pre-placement carbon dioxide immobilization process S20 is performed at the placement site, the temperature of the carbon dioxide immobilized fresh concrete obtained in the pre-placement carbon dioxide immobilization process S20, and the temperature of the carbon dioxide immobilized concrete obtained in the post-placement concrete hardening process S30, are lower than in conventional methods. Therefore, when constructing mass concrete structures using carbon dioxide immobilized concrete, the occurrence of cracks due to temperature rise during construction can be suppressed.
[0026] In the carbon dioxide immobilization process S20 before concrete placement, the supply ratio of γ-C2S to dry ice supplied to the fresh concrete is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, of dry ice per 100 parts by mass of γ-C2S. By supplying 5 parts by mass or more of dry ice per 100 parts by mass of γ-C2S, the temporal and spatial constraints on carbon dioxide immobilization can be further suppressed compared to conventional methods, and the amount of carbon dioxide that can be immobilized can be further increased. Furthermore, when constructing mass concrete structures, the occurrence of cracks due to temperature rise during construction can be further suppressed.
[0027] In the pre-placement carbon dioxide immobilization process S20, the supply ratio of γ-C2S to dry ice supplied to the fresh concrete is preferably 70 parts by mass or less of dry ice per 100 parts by mass of γ-C2S. Even if the amount of dry ice supplied significantly exceeds the theoretical absorbable value of 55.6 parts by mass per 100 parts by mass of γ-C2S, the results obtained will not change. By supplying 70 parts by mass or less of dry ice, it is possible to suppress the increase in material costs associated with the use of excessive dry ice and reduce the danger of handling dry ice.
[0028] In the carbon dioxide immobilization process S20 before concrete placement, the amount of γ-C2S supplied to the fresh concrete is 1 m³ of fresh concrete. 3 Preferably, it contains 1 kg or more per unit, more preferably 10 kg or more, and even more preferably 30 kg or more. The supply amount of γ-C2S to fresh concrete is 1 kg / m³. 3 As a result, compared to conventional methods, the temporal and spatial constraints on carbon dioxide fixation can be further reduced, and the amount of carbon dioxide that can be fixed can be further increased.
[0029] In the carbon dioxide immobilization process S20 before concrete placement, the amount of γ-C2S supplied to the fresh concrete is 1 m³ of fresh concrete. 3 Preferably, it contains 100 kg or less per unit, more preferably 50 kg or less, and even more preferably 40 kg or less. The supply amount of γ-C2S to fresh concrete is 100 kg / m³. 3 The following conditions can suppress the increase in material costs associated with the excessive use of γ-C2S.
[0030] Regarding the carbon dioxide-immobilized fresh concrete obtained in the carbon dioxide immobilization step S20 before placing, the substitution rate of γ-C2S is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. The substitution rate of the above γ-C2S can be calculated from the ratio of the unit amount of γ-C2S to the unit amount of cement, and γ-C2S is a proportion of the cement amount. When the substitution rate of γ-C2S in the carbon dioxide-immobilized fresh concrete is 5% or more, compared with the conventional fresh concrete not containing γ-C2S, the time and location constraints for carbon dioxide immobilization can be further suppressed, and the amount of carbon dioxide that can be immobilized can be further increased.
[0031] Regarding the supply timing of γ-C2S and the supply timing of dry ice to fresh concrete, the supply timing of γ-C2S and the supply timing of dry ice may overlap, or within the range where carbon dioxide can be immobilized in fresh concrete, the supply timing of γ-C2S and the supply timing of dry ice do not have to overlap.
[0032] In the carbon dioxide immobilization step S20 before placing, regarding the temperature of the fresh concrete at the time of supplying γ-C2S and dry ice, the lower limit value is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher, and the upper limit value is preferably 35°C or lower. As the temperature of the fresh concrete increases within the above temperature range, carbon dioxide can be efficiently immobilized in the fresh concrete, so the amount of carbon dioxide immobilized in the fresh concrete can be increased in a short time.
[0033] In the carbon dioxide immobilization step S20 before placing, for the fresh concrete in which the substitution rate of γ-C2S and the amounts of water (W), cement (C), and γ-C2S per 1 m 3 of fresh concrete are the values shown in Table 1, when the total supply amount of carbon dioxide for 5 minutes is set to 3.3 kg and the amount of carbon dioxide is supplied at a constant rate to obtain carbon dioxide-immobilized fresh concrete, the amount of carbon dioxide (kg / m 3The values for each minute after supplying carbon dioxide can be estimated as shown in Table 2. Here, the total amount of carbon dioxide supplied over 5 minutes, 3.3 kg, is obtained by multiplying the amount of binder by 1% (0.01). The binder is the sum of cement and γ-C2S.
[0034] Furthermore, Table 2 shows the amount of carbon dioxide immobilized in fresh concrete (kg / m³). 3 The relationship between ) and carbon dioxide supply time (min) is graphed in Figure 2.
[0035] [Table 1]
[0036] [Table 2]
[0037] As shown in Tables 1-2 and Figure 2, the γ-C2S replacement rate is 0%, and the amount of γ-C2S contained in the fresh concrete is 0 kg / m³. 3 Compared to ordinary concrete C (concrete that does not contain γ-C2S), in the carbon dioxide-immobilized concrete of this embodiment, the amount of carbon dioxide immobilized in the fresh carbon dioxide-immobilized concrete increases as the γ-C2S replacement rate and the amount of γ-C2S increase.
[0038] Furthermore, as shown in Figure 1, in the post-cast concrete hardening process S30, which is carried out after the pre-cast carbon dioxide immobilization process S20, the carbon dioxide-immobilized fresh concrete obtained in the pre-cast carbon dioxide immobilization process S20 is cast and hardened to obtain carbon dioxide-immobilized concrete. Carbon dioxide-immobilized concrete is concrete in which carbon dioxide has been immobilized, and is essentially concrete that has been carbonated.
[0039] In the post-placement concrete hardening process S30, the carbon dioxide-immobilized fresh concrete, which is a fluidized material, is cured in uncontrolled air after placement to harden, thereby obtaining carbon dioxide-immobilized concrete, which is a hardened material. Since carbon dioxide-immobilized concrete has carbon dioxide fixed in it, it contains calcium carbonate.
[0040] Hardened carbon dioxide-immobilized concrete contains a large amount of γ-C2S, similar to carbon dioxide-immobilized fresh concrete. Therefore, over a long period, the γ-C2S in the carbon dioxide-immobilized concrete reacts with carbon dioxide in the air (unforced ambient air), allowing the concrete to further immobilize carbon dioxide. The amount of carbon dioxide that can be further immobilized in carbon dioxide-immobilized concrete is significantly greater than the amount that can be immobilized in fresh concrete or carbon dioxide-immobilized fresh concrete, which are fluidized materials.
[0041] Therefore, the method for manufacturing carbon dioxide-immobilized concrete of the embodiment does not require a step (forced carbon dioxide immobilization step) in which a carbon dioxide source such as dry ice is further supplied to the carbon dioxide-immobilized fresh concrete and carbon dioxide-immobilized concrete after placement and before hardening to forcibly immobilize the carbon dioxide.
[0042] As described above, carbon dioxide-fixed concrete contains a large amount of γ-C2S. Furthermore, carbon dioxide-fixed concrete can fix a larger amount of carbon dioxide compared to fresh concrete or carbon dioxide-fixed fresh concrete. Therefore, even without the forced supply of a carbon dioxide source such as dry ice, as in the pre-placement carbon dioxide-fixation process S20, the fresh carbon dioxide-fixed concrete after placement, and the hardened carbon dioxide-fixed concrete that is the result of the fresh carbon dioxide-fixed concrete, can sufficiently fix carbon dioxide from the air.
[0043] Thus, the method for manufacturing carbon dioxide-fixed concrete according to the above embodiment can suppress the temporal and spatial constraints on carbon dioxide fixation compared to conventional methods. Furthermore, carbon dioxide-fixed concrete can sufficiently fix carbon dioxide. Therefore, carbon dioxide-fixed concrete has excellent environmental purification properties.
[0044] Furthermore, even without a forced carbon dioxide fixation process, carbon dioxide-fixed concrete can fixate more carbon dioxide than conventional concrete. Therefore, if the forced carbon dioxide fixation process is not performed, the ancillary equipment for that process becomes unnecessary, thus reducing manufacturing costs.
[0045] Furthermore, in the pre-concrete carbon dioxide immobilization process S20, it is preferable to contain γ-C2S and dry ice inside and supply the carbon dioxide immobilizer, which is composed of water-soluble materials, to the fresh concrete. The water-soluble materials that make up the carbon dioxide immobilizer can dissolve in the moisture contained in the fresh concrete and dissolve easily in about a few minutes. For example, the carbon dioxide immobilizer is stored in a refrigerated container until it is supplied to the fresh concrete.
[0046] Regarding the state of the γ-C2S and dry ice contained within the carbon dioxide immobilization agent, the γ-C2S and dry ice may be completely separated, or they may be mixed together. Furthermore, even if a worker touches the carbon dioxide immobilization agent containing the γ-C2S and dry ice, the worker will not come into contact with the γ-C2S or dry ice.
[0047] When a carbon dioxide immobilizer, which integrates γ-C2S and dry ice, is supplied to fresh concrete, the water-soluble materials constituting the carbon dioxide immobilizer are dissolved by the moisture contained in the fresh concrete, causing the γ-C2S and dry ice to escape from within the carbon dioxide immobilizer. As a result, the moisture in the fresh concrete acts as a starting point, and the carbon dioxide generated by the sublimation of the dry ice reacts with the γ-C2S, allowing the carbon dioxide to be immobilized within the fresh concrete.
[0048] As described above, even if a worker handles the carbon dioxide immobilizer, they will not come into contact with the γ-C2S and dry ice within the immobilizer. Therefore, in this method of supplying the carbon dioxide immobilizer to fresh concrete, the worker can supply both γ-C2S and dry ice to the fresh concrete at once without directly touching them by adding the carbon dioxide immobilizer to the fresh concrete. This improves worker safety and allows for easy supply of γ-C2S and dry ice together. Furthermore, using a carbon dioxide immobilizer eliminates the need for dust control measures during work using powdered γ-C2S.
[0049] Furthermore, by adding a carbon dioxide immobilizing agent to fresh concrete, γ-C2S and dry ice can be easily supplied to the fresh concrete in the desired ratio. Therefore, the work of weighing γ-C2S and dry ice at the concrete placement site is eliminated, and the amount of γ-C2S and dry ice added at the concrete placement site becomes easier to manage.
[0050] The shape of the carbon dioxide immobilizer can be appropriately selected depending on the method of supplying the carbon dioxide immobilizer to the fresh concrete. For example, the shape of the carbon dioxide immobilizer may be a fixed shape such as a sphere or polygon, or it may be an irregular shape such as a bag.
[0051] The ratio of γ-C2S to dry ice in the carbon dioxide immobilizer can be appropriately set according to the composition of the fresh concrete. The number of carbon dioxide immobilizer units supplied to the fresh concrete can also be appropriately set according to the amount of fresh concrete, the amount of γ-C2S and dry ice in the carbon dioxide immobilizer, and other factors. From the viewpoint of work efficiency, it is preferable that the total amount of γ-C2S and dry ice contained in the carbon dioxide immobilizer be approximately 2 kg.
[0052] From the viewpoint of easily dissolving the water-soluble materials constituting the carbon dioxide fixative with the moisture in the fresh concrete, the water-soluble materials are preferably water-soluble films or water-soluble paper. Water-soluble films are manufactured, for example, using polyvinyl alcohol as a raw material. Water-soluble paper is manufactured using wood pulp, polysaccharides, polyvinyl alcohol, cellulose, polyvinyl alcohol, carboxymethylcellulose, starch, etc., as raw materials.
[0053] From the viewpoint of maintaining the ratio of γ-C2S to dry ice in the carbon dioxide immobilization agent, it is preferable that the water-soluble material constituting the carbon dioxide immobilization agent has barrier properties against carbon dioxide.
[0054] From the viewpoint of sublimating dry ice in a short time, the size of the dry ice contained in the carbon dioxide fixing agent is preferably 50 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. Such small dry ice can be easily produced by a freeze-pulverizing device.
[0055] From the viewpoint of ease of handling of the carbon dioxide immobilization agent and ease of operation of the pre-casting carbon dioxide immobilization process S20 using an agitator truck, which will be described later, the size of the carbon dioxide immobilization agent is preferably 10 cm to 40 cm, and in particular, the upper limit is preferably smaller than the input opening of the agitator truck.
[0056] In the above description, we explained an example in which the carbon dioxide fixative contains both γ-C2S and dry ice. However, carbon dioxide fixatives containing only γ-C2S or only dry ice may also be supplied to fresh concrete.
[0057] Figure 3 is a schematic diagram showing an example of a method for supplying the carbon dioxide immobilization agent in the carbon dioxide immobilization process before concrete placement. In Figure 3 and Figure 4 described later, an example is shown in which the carbon dioxide immobilization agent 1 is spherical, and the γ-C2S containment portion 1a (hereinafter also referred to as the γ-C2S containment portion 1a) contained within the carbon dioxide immobilization agent 1 occupies one half of the carbon dioxide immobilization agent 1, while the dry ice containment portion 1b (hereinafter also referred to as the dry ice containment portion 1b) occupies the other half of the carbon dioxide immobilization agent 1. Furthermore, the carbon dioxide immobilization agent 1 moves from left to right in the diagram.
[0058] As shown in Figure 3, the carbon dioxide immobilizer supply member 10, which extends in a straight line, is positioned so that one end on the fresh concrete side is lowered. The position of the carbon dioxide immobilizer supply member 10 is maintained by a worker (not shown) or fixing device (not shown). Here, the right side of the drawing is considered the fresh concrete side. The weight of the carbon dioxide immobilizer supply member 10 is such that it can be supported by one worker. The length of the carbon dioxide immobilizer supply member 10 is, for example, several meters.
[0059] Then, when the carbon dioxide immobilizer 1 is placed on the left side of the carbon dioxide immobilizer supply member 10, the carbon dioxide immobilizer 1 rolls along the carbon dioxide immobilizer supply member 10 toward the right side of the diagram and is poured into the fresh concrete from the right end of the carbon dioxide immobilizer supply member 10.
[0060] Thus, the carbon dioxide immobilizer supply member 10 can be handled by one worker, and the carbon dioxide immobilizer 1 can be reliably supplied to the fresh concrete by having the same worker or another worker place the carbon dioxide immobilizer 1 onto the carbon dioxide immobilizer supply member 10. Therefore, the carbon dioxide immobilizer 1 can be safely and easily added with a small number of workers using simple tools.
[0061] In Figure 3, an example is shown where the carbon dioxide immobilizer 1 is spherical. However, if the carbon dioxide immobilizer 1 has a shape other than spherical, the carbon dioxide immobilizer 1 will move by sliding on the carbon dioxide immobilizer supply member 10. Furthermore, the carbon dioxide immobilizer supply member 10 is preferably of the conveyor type or chute type.
[0062] From the viewpoint of allowing the carbon dioxide immobilizer 1 to move easily on the carbon dioxide immobilizer supply member 10, it is preferable that the surface of the carbon dioxide immobilizer supply member 10 that comes into contact with the carbon dioxide immobilizer 1 (the upper surface of the carbon dioxide immobilizer supply member 10) is made of a material with a low coefficient of friction. Also, from the same viewpoint, it is preferable that rotating rollers are locally provided on the surface of the carbon dioxide immobilizer supply member 10 that comes into contact with the carbon dioxide immobilizer 1.
[0063] Figure 4 is a schematic diagram showing another example of a method for supplying carbon dioxide immobilization agent in the pre-casting carbon dioxide immobilization process. Multiple carbon dioxide immobilization agents 1 are contained within the carbon dioxide immobilization agent containment member 20 shown in Figure 4. An open / close mechanism 21, which can be opened and closed, is provided on the lower side of the carbon dioxide immobilization agent containment member 20. A carbon dioxide immobilization agent supply member 10 is positioned below the open / close mechanism 21 of the carbon dioxide immobilization agent containment member 20. The weight of the carbon dioxide immobilization agent containment member 20 is such that it can be carried on the back of one worker. The carbon dioxide immobilization agent containment member 20 is preferably in the form of a backpack or attaché case.
[0064] Then, when the opening / closing section 21 of the carbon dioxide immobilization agent containment member 20 opens, the carbon dioxide immobilization agent 1 that was contained inside the carbon dioxide immobilization agent containment member 20 exits the carbon dioxide immobilization agent containment member 20 through the opening / closing section 21. The carbon dioxide immobilization agent 1 that has moved from the carbon dioxide immobilization agent containment member 20 to the carbon dioxide immobilization agent supply member 10 moves along the carbon dioxide immobilization agent supply member 10 toward the right side of the drawing, and is poured into the fresh concrete from the right end of the carbon dioxide immobilization agent supply member 10 in the drawing.
[0065] Thus, the carbon dioxide immobilizer container 20 can be carried on the back of a single worker, and the same worker can reliably supply the carbon dioxide immobilizer 1 to the fresh concrete by operating the opening and closing mechanism of the carbon dioxide immobilizer container 20. Therefore, the carbon dioxide immobilizer 1 can be safely and easily added by a single worker using simple tools.
[0066] Furthermore, even if it rains during the work, the carbon dioxide immobilizer 1 contained inside the carbon dioxide immobilizer container 20 can be prevented from dissolving in the rain. Therefore, the carbon dioxide immobilizer 1 can be supplied to fresh concrete regardless of the weather.
[0067] Furthermore, even if carbon dioxide leaks from the carbon dioxide immobilizer 1 contained in the carbon dioxide immobilizer containment member 20, the carbon dioxide will be released to the outside of the carbon dioxide immobilizer containment member 20 through the opening / closing section 21 located on the underside of the carbon dioxide immobilizer containment member 20. Therefore, the risk of health damage caused by workers directly inhaling carbon dioxide released to the outside of the carbon dioxide immobilizer containment member 20 can be suppressed.
[0068] Furthermore, from the viewpoint of maintaining a low temperature inside the carbon dioxide immobilization agent containment member 20 and storing the carbon dioxide immobilization agent 1 at a low temperature, it is preferable that a cooling sheet (not shown) is provided inside the carbon dioxide immobilization agent containment member 20. Also, from the viewpoint of easily removing the carbon dioxide immobilization agent 1 from the opening / closing part 21 of the carbon dioxide immobilization agent containment member 20, it is preferable that an inclined part (not shown) that slopes toward the opening / closing part 21 is provided on the bottom surface of the carbon dioxide immobilization agent containment member 20.
[0069] Figure 5 is a schematic diagram showing an example of the main components of an agitator vehicle used in the carbon dioxide-fixed concrete manufacturing method of the embodiment. As shown in Figure 5, the agitator vehicle 31 is equipped with a rotating drum 32 at the rear and a driver's seat 33 at the front. The rotating drum 32 is installed with an incline so that the rear is higher and the front is lower. A rotary drive device 34 for rotating the rotating drum 32 is connected to the rotating drum 32.
[0070] In the pre-placement carbon dioxide immobilization step S20, it is preferable to supply γ-C2S and dry ice together to the fresh concrete 50 stored in the agitator truck 31, and more preferably to supply the carbon dioxide immobilization agent 1. The fresh concrete produced in the fresh concrete manufacturing step S10 is poured in from the hopper, which is the input port 35, and stored inside the rotating drum 32. By supplying γ-C2S and dry ice, or the carbon dioxide immobilization agent 1, to the fresh concrete 50 stored in the rotating drum 32 of the agitator truck 31 and stirring, the pre-placement carbon dioxide immobilization step S20 can be carried out inside the rotating drum 32. As a result, carbon dioxide immobilized fresh concrete, in which carbon dioxide is immobilized in the fresh concrete 50, can be obtained inside the rotating drum 32.
[0071] In the carbon dioxide immobilization process S20 before concrete pouring in such a rotating drum 32, γ-C2S and dry ice, or carbon dioxide immobilization agent 1 may be supplied into the rotating drum 32 from a supply unit (not shown) connected to the rotating drum 32. However, since the existing agitator vehicle 31 can be used as is without modification, it is preferable to supply γ-C2S and dry ice, or carbon dioxide immobilization agent 1 from outside the agitator vehicle 31. Among these, in terms of ease of supply into the rotating drum 32 and safety, it is preferable to supply γ-C2S and dry ice, or carbon dioxide immobilization agent 1 into the rotating drum 32 from outside the rotating drum 32 via the input port 35.
[0072] This pre-placement carbon dioxide immobilization process S20 using the agitator truck 31 is performed inside the agitator truck 31 at the placement site of the carbon dioxide immobilized fresh concrete. When discharging the carbon dioxide immobilized fresh concrete, the rotating drum 32 is rotated, and the carbon dioxide immobilized fresh concrete is pushed out from the discharge port 37 of the rotating drum 32 by a screw plate 36 provided inside the rotating drum 32. The carbon dioxide immobilized fresh concrete pushed out from the rotating drum 32 is guided from the scoop 38 to the chute 39 and discharged to the outside. The carbon dioxide immobilized fresh concrete thus discharged is then used for the post-placement concrete hardening process S30.
[0073] Figure 6 is a schematic diagram showing an example of a pre-concrete carbon dioxide immobilization process using an agitator truck. As shown in Figure 6, in the pre-concrete carbon dioxide immobilization process S20, it is preferable to supply the carbon dioxide immobilizer 1 to the fresh concrete 50 stored in the rotating drum 32 of the agitator truck 31 using the carbon dioxide immobilizer supply member 10 and the carbon dioxide immobilizer containment member 20.
[0074] Specifically, as shown in Figure 6, in the carbon dioxide immobilization process S20 before concrete placement, the carbon dioxide immobilization agent supply member 10 is installed such that one end is inserted into the rotating drum 32 of the agitator vehicle 31 through the inlet 35 of the agitator vehicle 31, and the other end is outside the agitator vehicle 31 and at a higher position than the one end.
[0075] Furthermore, the carbon dioxide immobilization agent containment member 20, which contains multiple carbon dioxide immobilization agents 1. Each carbon dioxide immobilization agent 1 contains powdered γ-C2S and dry ice with a particle size of 50 mm or less.
[0076] Then, the carbon dioxide immobilizer 1 is transferred from the opening / closing section 21 of the carbon dioxide immobilizer containment member 20 to the other end of the carbon dioxide immobilizer supply member 10 by falling or other means. The carbon dioxide immobilizer 1 that has moved to the other end of the carbon dioxide immobilizer supply member 10 moves toward the one end of the carbon dioxide immobilizer supply member 10 and supplies the carbon dioxide immobilizer 1 to the fresh concrete 50 stored in the rotating drum 32 of the agitator vehicle 31. In this way, the carbon dioxide immobilizer 1 can be reliably supplied to the fresh concrete 50 in the rotating drum 32 without having to throw the carbon dioxide immobilizer 1 towards the input port 35.
[0077] For example, a worker possessing a carbon dioxide immobilizer container 20 supplies the carbon dioxide immobilizer 1 to the fresh concrete 50 in the rotating drum 32 via a carbon dioxide immobilizer supply member 10 from a lifting stage constructed from a ladder (not shown) attached to the agitator truck 31 or from a scaffolding (not shown) set up near the agitator truck 31. Multiple carbon dioxide immobilizer containers 20 may be loaded onto the lifting stage. Alternatively, the carbon dioxide immobilizer container 20 may be handed to the worker using a small crane or the like.
[0078] Furthermore, if the supply amount of carbon dioxide immobilization agent 1 is small, the carbon dioxide immobilization agent 1 may be supplied using the carbon dioxide immobilization agent containment member 20 instead of the carbon dioxide immobilization agent supply member 10. In this case, the worker holding the carbon dioxide immobilization agent containment member 20 will pour the carbon dioxide immobilization agent 1 from the ladder or lifting stage of the agitator truck 31 towards the input port 35 to supply the carbon dioxide immobilization agent 1 to the fresh concrete 50 in the rotating drum 32.
[0079] When the carbon dioxide immobilizer 1 is supplied to the fresh concrete 50, the water-soluble materials constituting the carbon dioxide immobilizer 1 dissolve in the moisture in the fresh concrete 50, causing the γ-C2S and dry ice contained within the carbon dioxide immobilizer 1 to be mixed into the fresh concrete 50. As a result of supplying γ-C2S and dry ice to the fresh concrete 50, carbon dioxide can be immobilized in the fresh concrete 50.
[0080] Subsequently, the fixed fresh concrete produced in the rotating drum 32 of the agitator truck 31 is discharged outside the rotating drum 32 and poured into the frame 60 installed at the pouring site. The fixed fresh concrete 70 poured into the frame 60 hardens by curing in the air, becoming carbon dioxide fixed concrete.
[0081] Furthermore, the carbon dioxide-fixed concrete obtained by the above manufacturing method is 1 m³ of carbon dioxide-fixed concrete. 3 Each unit contains 0.1 kg to 50 kg of carbon dioxide derived from calcium carbonate. Among these, carbon dioxide-immobilized concrete obtained using an agitator truck, that is, carbon dioxide-immobilized concrete obtained by performing the pre-placement carbon dioxide immobilization process S20 in which γ-C2S and dry ice are supplied to fresh concrete stored in the agitator truck, is carbon dioxide-immobilized concrete 1 m 3 Each portion contains between 2 kg and 10 kg of carbon dioxide derived from calcium carbonate. As described above, the method for manufacturing carbon dioxide-immobilized concrete of this embodiment can suppress the temporal and spatial constraints on carbon dioxide immobilization compared to conventional methods. Therefore, carbon dioxide-immobilized concrete obtained by the above manufacturing method can immobilize more carbon dioxide than conventional methods. The amount of immobilized carbon dioxide is the value measured by solid matter thermogravimetric analysis for carbon dioxide-immobilized concrete 28 days after hardening of fresh carbon dioxide-immobilized concrete.
[0082] Although embodiments have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concepts and claims of this disclosure, and can be modified in various ways within the scope of this disclosure. [Explanation of Symbols]
[0083] 1. Carbon dioxide fixative 1a γ-C2S housing 1b Dry ice storage section 10 Carbon dioxide immobilization agent supply member 20 Carbon dioxide immobilization agent containment member 31 Agitator vehicles 32 RPM drum 33 Driver's seat 34 Rotary drive device 35 Inlet 36 Screw Plate 37 Outlet 38 Scoops 39 shots 50 Fresh concrete 60 Frame 70 Stabilized Fresh Concrete
Claims
1. A method for manufacturing carbon dioxide-fixed concrete in which a predetermined amount of carbon dioxide is fixed in concrete, The fresh concrete manufacturing process, which produces fresh concrete, At the concrete placement site, γ-C is added to the fresh concrete produced in the fresh concrete manufacturing process. ２ A pre-placement carbon dioxide immobilization step is performed by supplying S and dry ice together and stirring to obtain carbon dioxide immobilized fresh concrete in which carbon dioxide is immobilized in the fresh concrete. The carbon dioxide-fixed fresh concrete obtained in the pre-casting carbon dioxide-fixing process is cast and hardened in the post-casting concrete hardening process to obtain carbon dioxide-fixed concrete. It has, In the carbon dioxide fixation process before concrete placement, γ-C ２ A method for producing carbon dioxide-fixed concrete, comprising containing S and dry ice inside, and supplying a carbon dioxide-fixing agent composed of a water-soluble material to the fresh concrete.
2. In the carbon dioxide fixation process before concrete placement, γ-C is supplied to the fresh concrete. ２ The supply ratio of S to dry ice is γ-C ２ A method for producing carbon dioxide-immobilized concrete according to claim 1, wherein the dry ice is present in an amount of 5 to 70 parts by mass per 100 parts by mass of S.
3. In the carbon dioxide fixation process before concrete placement, γ-C is supplied to the fresh concrete. ２ The amount of S supplied is 1 m of fresh concrete. ３ A method for producing carbon dioxide-fixed concrete according to claim 1 or 2, wherein the amount is 1 kg or more and 100 kg or less per unit.
4. The carbon dioxide-fixed concrete is the carbon dioxide-fixed concrete 1 m ３ A method for producing carbon dioxide-immobilized concrete according to any one of claims 1 to 3, wherein the product contains 0.1 kg to 50 kg of carbon dioxide derived from calcium carbonate per unit.
5. The aforementioned pre-casting carbon dioxide fixation process involves adding γ-C to the fresh concrete stored in the agitator vehicle. ２ A method for producing carbon dioxide-immobilized concrete according to any one of claims 1 to 3, comprising supplying S and dry ice.
6. The carbon dioxide immobilization step before placing supplies γ-C ２ S and dry ice from the outside of the agitator truck, and the method for producing carbon dioxide immobilized concrete according to claim 5.
7. The carbon dioxide immobilization step before concrete placement involves inserting one end of the carbon dioxide immobilization agent supply member into the rotating drum of the agitator vehicle through the inlet of the agitator vehicle, and positioning the other end of the carbon dioxide immobilization agent supply member so that it is outside the agitator vehicle and higher than the one end, and then distributing the powdered γ-C ２ A method for manufacturing carbon dioxide-immobilized concrete according to claim 1, comprising: transferring the carbon dioxide-immobilizing agent from a carbon dioxide-immobilizing agent containing a plurality of carbon dioxide-immobilizing agents containing S and dry ice with a particle size of 50 mm or less to the other end of the carbon dioxide-immobilizing agent supply member; moving the carbon dioxide-immobilizing agent toward one end of the carbon dioxide-immobilizing agent supply member; and supplying the carbon dioxide-immobilizing agent to the fresh concrete stored in the rotating drum of the agitator vehicle.
8. The carbon dioxide-fixed concrete is the carbon dioxide-fixed concrete 1 m ３ A method for producing carbon dioxide-immobilized concrete according to any one of claims 5 to 7, wherein each portion contains 2 kg to 10 kg of carbon dioxide derived from calcium carbonate.