Carbon dioxide fixation material, method for manufacturing carbon dioxide fixation material, method for manufacturing hydraulic composition, carbon dioxide fixation material manufacturing device, and hydraulic composition manufacturing device

Abstract

To provide a carbon dioxide immobilization material which can manufacture uniform cement mortar and concrete, has suppressed influence on a reinforcement material such as a steel bar, and can be manufactured by using a general facility, a manufacturing method of a carbon dioxide immobilization material, and a manufacturing method of a hydraulic composition.SOLUTION: Disclosed are a carbon dioxide immobilization material comprising an aggregate S1 and a paste coating the aggregate S1, a manufacturing method of this carbon dioxide immobilization material, and a manufacturing method of a hydraulic composition containing the carbon dioxide immobilization material. The paste is a mixture of a binder C1 for a hydraulic composition and water W1, and carbon dioxide in a supplied gas is immobilized while kneading the aggregate S1 with water W1 and the binder C1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide fixing material, a method for producing the carbon dioxide fixing material, and a method for producing a hydraulic composition. [Background technology]

[0002] Various efforts have been made to reduce carbon dioxide emissions, which are said to be the cause of global warming. For example, Patent Document 1 discloses a technology in which carbon dioxide emitted from industry is liquefied and this liquefied carbon dioxide is mixed with mixing water when ready-mixed concrete is produced. This technology is based on the elimination of calcium ions (Ca 2+ The carbon dioxide is immobilized in the concrete by reacting calcium carbonate (CaCO3) with carbon dioxide (CO2). Patent Document 2 also discloses a method for producing a hardened cement body with a densified surface layer by exposing the hardened cement body during curing to carbon dioxide gas to carbonate the surface layer. However, the technology described in Patent Document 1 involves feeding materials into a large mixer and mixing them all at once, which can lead to variations in the quality of the concrete, such as strength development and the amount of carbon dioxide fixed. Furthermore, production is limited to plants equipped with large mixers. The technology in Patent Document 2 involves carbonating the surface of concrete members, which can lead to corrosion of the reinforcing steel bars inside. This requires a large covering thickness, which can hinder the reduction of the cross-section of the members. Furthermore, the technology requires sealing during curing, which limits its application to secondary products. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-510274 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-149456 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a carbon dioxide fixing material, a method for manufacturing a carbon dioxide fixing material, and a method for manufacturing a hydraulic composition that can produce homogeneous mortar or concrete, minimize the effect on reinforcing materials such as steel bars, and enable production using general equipment. Note that the hydraulic composition in this specification includes not only mortar or concrete mainly made of a cement-based material, but also mortar or concrete mainly made of a hydraulic material other than cement. [Means for solving the problem]

[0005] The first carbon dioxide fixation material of the present invention for solving the above problems comprises aggregate and a paste covering the aggregate. The paste is a mixture of a binder for a hydraulic composition and water, and fixes carbon dioxide in gas supplied during kneading of the aggregate, water, and binder. This carbon dioxide fixation material can be produced by mixing aggregate, water, and a binder for a hydraulic composition in the mixer while supplying a gas containing carbon dioxide, thereby fixing the carbon dioxide in a paste that is a mixture of the binder and the water, and coating the aggregate with the paste. That is, the first method for producing a hydraulic composition includes a primary kneading step of mixing aggregate, primary water, and a primary binder in a mixer and coating the aggregate with a primary paste that is a mixture of the primary water and the primary binder to produce a carbon dioxide fixing material, and a secondary kneading step of kneading the carbon dioxide fixing material, secondary water, and secondary binder to produce a hydraulic composition. In the primary kneading step, a gas containing carbon dioxide is supplied into the mixer, and the carbon dioxide contained in the gas is fixed in the primary paste.

[0006] The aggregate may be either fine aggregate or coarse aggregate, or may be both fine aggregate and coarse aggregate. In addition, the amount of the aggregate is 1 m 3 In the second mixing step, the remaining amount of aggregate may be mixed. In other words, the aggregate may be added in two separate steps.

[0007] A second carbon dioxide fixation material of the present invention comprises coarse aggregate and mortar covering the coarse aggregate. The mortar is a mixture of a binder for a hydraulic composition, water, and fine aggregate, and fixes carbon dioxide in gas supplied during mixing of the coarse aggregate, the water, the binder, and the fine aggregate. This carbon dioxide fixation material can be produced by mixing coarse aggregate, fine aggregate, water, and a binder for a hydraulic composition in a mixer while supplying a gas containing carbon dioxide, thereby fixing the carbon dioxide in mortar, which is a mixture of the binder, the water, and the fine aggregate, and coating the coarse aggregate with the mortar. That is, the second method for producing a hydraulic composition includes a primary kneading step of producing a carbon dioxide fixing material by mixing coarse aggregate, fine aggregate, primary water, and a primary binder in a mixer and coating the coarse aggregate with primary mortar, which is a mixture of the fine aggregate, the primary water, and the primary binder, and a secondary kneading step of kneading the carbon dioxide fixing material, secondary water, and the secondary binder to produce a hydraulic composition. In the primary kneading step, a gas containing carbon dioxide is supplied into the mixer, and the carbon dioxide contained in the gas is fixed in the primary mortar.

[0008] The amount of the coarse aggregate is 1 m 3 The amount of the fine aggregate is a part of the amount of the coarse aggregate per m3 at the time of mix design of the hydraulic composition, and the remaining amount of the coarse aggregate may be mixed in the secondary mixing step. 3 In the second mixing step, the remaining amount of fine aggregate may be mixed. In other words, the coarse aggregate and the fine aggregate may be added in two separate steps.

[0009] The carbon dioxide fixation material of the present invention contains calcium carbonate (CaCO3) precipitated by the reaction of carbon dioxide (CO2) with calcium (Ca) in a binder. Specifically, the carbon dioxide fixation material and method for producing the carbon dioxide fixation material of the present invention fix carbon dioxide in paste or mortar, thereby contributing to carbon dioxide reduction. The carbon dioxide fixation material of the present invention can be used as a new aggregate in concrete production. The method for producing a hydraulic composition of the present invention effectively confines carbon dioxide within the hydraulic composition. Furthermore, the carbon dioxide fixation material in the hydraulic composition is covered with a secondary paste (a mixture of secondary water and a secondary binder) or secondary mortar, making the hydraulic composition alkaline and suppressing corrosion of reinforcing bars. Furthermore, the hydraulic composition or carbon dioxide fixation material can be produced using general concrete production equipment without requiring large-scale facilities, allowing for easy and low-cost production. Here, the binder (primary binder and secondary binder) includes at least one of blast furnace slag, expanding agent, hydrated lime, quicklime, fly ash, and Portland cement. The gas is not limited to gas containing carbon dioxide, and includes, for example, air, carbon dioxide gas with a higher carbon dioxide content than air, liquefied carbon dioxide gas, exhaust gas, etc.

[0010] The total amount of the primary water and the secondary water is set to 1 m 3 The amount of secondary water may be determined as the amount of water blended per 1 m3 of the hydraulic composition when the hydraulic composition is blended. 3 The amount of water to be mixed per 1 m3 of the mix design can also be used. 3 The additive may be added as an internal proportion or an external proportion to the hydraulic composition. In addition, the amount of the secondary binder is set to 1 m 3 The total amount of the primary binder and the secondary binder may be used as the blending amount per 1 m3 at the time of mix design. 3The amount of binder may be determined by adding it to the hydraulic composition per unit area. 3 The primary binder may be added as an external proportion to the hydraulic composition per unit weight, and carbon dioxide may be fixed by the primary binder added as an external proportion. 3 It may be added in proportion to the hydraulic composition. [Effects of the Invention]

[0011] According to the carbon dioxide fixation material, the method for producing the carbon dioxide fixation material, and the method for producing the hydraulic composition of the present invention, it is possible to produce homogeneous mortar or concrete, have little effect on reinforcing materials such as steel bars, and produce the hydraulic composition using general equipment. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart showing the steps of a method for producing a hydraulic composition according to the present embodiment. [Figure 2] FIG. 2 is a block diagram schematically showing the timing of adding materials in a method for producing a hydraulic composition. [Figure 3] 2 is a graph showing the compressive strength of the mortar according to Example 1. [Figure 4] FIG. 1(a) is a block diagram showing the timing of adding materials in the method for producing hydraulic compositions according to Examples 2 and 4, and FIG. 1(b) is a block diagram showing the timing of adding materials in the method for producing hydraulic compositions according to Examples 3 and 5. [Figure 5] 10 is a graph showing the compressive strength of concrete according to Example 3. [Figure 6] 1 is a graph showing the compressive strength of concrete according to Example 2 and Example 4 at 7 days old. [Figure 7] 1 is a graph showing the compressive strength of concretes according to Examples 2 and 4 at 14 days old. [Figure 8] 1 is a graph showing the compressive strength of concretes according to Examples 2 and 4 at an age of 28 days. DETAILED DESCRIPTION OF THE INVENTION

[0013] In this embodiment, a case where an environmentally friendly mortar (hydraulic composition) is produced will be described. The mortar of this embodiment contains cement (binder), water, aggregate, and admixture, and aims to reduce carbon dioxide emissions by immobilizing calcium carbonate produced by reacting alkali in the cement (binder) with carbon dioxide. The blending of the binder, water, aggregate, and admixture allows the mortar to exhibit the required strength. The material used for the aggregate is not limited, and may be collected from mountains, seas, rivers, etc., or may be recycled aggregate or aggregate recovered from washing wastewater at concrete plants (so-called recovered aggregate). Water may be tap water, river water, drainage water from construction work (including spring water), sludge water or supernatant water collected at concrete plants, etc. The method for producing mortar according to this embodiment will be described below. Fig. 1 shows the steps of the method for producing mortar. As shown in Fig. 1, the method for producing mortar according to this embodiment includes a primary mixing step S10 and a secondary mixing step S20. The primary mixing step S10 is a step for producing a carbon dioxide fixing material, and includes a water-aggregate mixing step S11 and an aggregate coating step S12. Fig. 2 schematically shows the timing of adding materials in the method for producing mortar.

[0014] In the water-aggregate mixing step S11, as shown in Fig. 2, the primary aggregate S1 and the primary water W1 are mixed in a mixer for a predetermined time. The primary aggregate S1 is a fine aggregate, and the amount of the primary aggregate S1 is set to 1 / m3 in the mortar mix design. 3 The amount of primary water is a part of the amount of aggregate per 1 m3 at the time of mortar mix design. 3 This is part of the amount of water used per batch.

[0015] In the aggregate coating step S12, a primary binder C1 is added to the mixer and kneaded for a predetermined time to produce a carbon dioxide fixation material consisting of primary aggregate S1 coated with a primary paste, which is a mixture of primary binder C1 and primary water W1. The carbon dioxide fixation material in this embodiment is granular. Note that the carbon dioxide fixation material may be in a slurry state rather than granular, depending on the amount of water, etc. After kneading, the mixer is covered and allowed to stand for a predetermined time. The primary binder C1 in this embodiment is made of cement. The amount of primary binder C1 mixed is 1 / 3 of the amount of primary binder C1 in the mortar mix design. 3 The amount is set separately from the amount of binder (cement) per unit. In other words, the primary binder C1 is added by the so-called outside ratio, and is used in the mortar mix design for 1 m 3 The amount of binder added is less than the amount of binder mixed per unit time. In the aggregate covering step S12, gas containing carbon dioxide (CO2) is supplied into the mixer while mixing is being performed. This causes the carbon dioxide (CO2) contained in the gas to react with the alkali in the cement, and the generated calcium carbonate is fixed in the paste. The timing of supplying the gas into the mixer is not limited, but for example, it can be started a predetermined time after the primary binder C1 is added to the mixer.

[0016] The secondary mixing step S20 is a step of producing mortar (hydraulic composition) by adding and kneading (secondary mixing) a carbon dioxide fixing material, secondary aggregate S2, secondary water W2, secondary binder C2, and admixture AD. The amount of secondary aggregate S2 is 1m 3 The amount of primary aggregate S1 is the amount of aggregate per 1 m3 minus the amount of secondary aggregate S2. 3 The amount of aggregate per unit. The amount of secondary water W2 is 1 m 3 The amount of water to be mixed is the amount obtained by subtracting the amount of primary water W1 from the amount of water to be mixed per 1 m3 of mortar. 3 This is the amount of water used per unit. The amount of secondary binder C2 is 1m 3 The amount of binder per unit.

[0017] According to the mortar manufacturing method of this embodiment, it is possible to fix calcium carbonate (CaCO3) precipitated by the reaction of carbon dioxide (CO2) with alkali in cement in the paste that coats the fine aggregate. Therefore, by using the carbon dioxide fixation material of this embodiment, carbon dioxide generated in industrial activities can be fixed on the surface of the aggregate and trapped within the mortar or concrete, thereby contributing to the reduction of carbon dioxide emissions. Carbon dioxide can be easily supplied because liquefied carbon dioxide (carbon dioxide gas) is injected and mixed directly into the mixer without dissolving it in water. Furthermore, because the carbon dioxide fixation material in the mortar is covered with the secondary paste (a mixture of secondary water and secondary binder), the mortar (hydraulic composition) becomes alkaline. Therefore, even when reinforcing materials such as steel bars are embedded inside, corrosion of the reinforcing materials can be suppressed. Therefore, when placing reinforcing bars, there is no need to increase the covering thickness more than necessary. Furthermore, since the hydraulic composition can be produced using general concrete or mortar production equipment without requiring large-scale facilities, mortar can be produced easily and at low cost. Furthermore, since the hydraulic composition is produced in predetermined amounts using general production equipment, a more uniform hydraulic composition (mortar) can be produced compared to when large-scale production equipment is used.

[0018] The results of checking the alkalinity of the carbon dioxide fixing material and mortar produced by the mortar production method of this embodiment are shown below. The composition of the mortar (Example 1) produced in this test is shown in Table 1. As shown in Table 1, the primary binder is a large proportion. In this test, a portion of the aggregate (primary aggregate S1) is added in the primary mixing step S10, and the remaining aggregate (secondary aggregate S2) is added in the secondary mixing step S20. In addition, as a comparative example, a mortar with the same composition as Example 1 was also produced in which no carbon dioxide-containing gas was supplied in the aggregate covering step. The admixture may be in an amount of 0.8% of the primary binder (cement) C1.

[0019] [Table 1]

[0020] Even when phenolphthalein solution was sprayed onto the carbon dioxide fixing material after the primary mixing (primary mixing step S10), the color of the aggregate did not change. On the other hand, as a comparative example, when phenolphthalein solution was sprayed onto aggregate in the primary mixing step S10 in which gas was not injected, the color changed to reddish purple. Therefore, it was confirmed that the alkali in the paste (cement) covering the aggregate reacted with carbon dioxide to produce calcium carbonate and neutralize the carbon dioxide fixing material. Next, the compressive strength of the test specimens manufactured using the mortar after the secondary mixing (secondary mixing step S20) was measured. The measurement results are shown in Figure 3. As shown in Figure 3, the compressive strength of the comparative example: about 20.0 N / mm 2 In contrast, in Example 1, the compressive strength was approximately 26.0 N / mm 2 There was no decrease in strength. Furthermore, when the specimen of Example 1 was broken and a phenolphthalein solution was sprayed on the broken surface, the color changed to reddish purple. When the phenolphthalein solution was sprayed on the specimen of Comparative Example in the same manner, the color also changed to reddish purple. Therefore, it was confirmed that the mortar of this embodiment was not neutralized.

[0021] Next, 1 m of mortar of this embodiment 3The amount of carbon dioxide fixed relative to the initial mixing amount will be explained. Table 2 shows the results of thermogravimetric analysis performed on mortar 30 minutes after the primary mixing. Sample A is the result of mixing for 10 minutes within the 30 minutes after the primary mixing. Sample B is the result of mixing for 15 minutes within the 30 minutes after the primary mixing. As shown in Table 2, the carbon dioxide (CO2) percentage (Sample A: 7.80%, Sample B: 7.27%) was calculated. The obtained values ​​were converted to molecular weight to calculate the calcium carbonate (CaCO3) content (Sample A: 17.74, Sample B: 16.52).

[0022] [Table 2]

[0023] Next, the amount of calcium carbonate (CaCO3) is calculated. The calculation results of the amount of calcium carbonate (CaCO3) are shown in Table 3. The amount of calcium carbonate (CaCO3) is calculated by multiplying the total mass of cement and fine aggregate at the time of primary mixing by the content of calcium carbonate (CaCO3). As shown in Table 3, 1 m of sample A 3 The amount of calcium carbonate (CaCO3) per 1 m of sample B is 45.41 kg. 3 The amount of calcium carbonate (CaCO3) per 1 m3 was 42.30 kg. The amount of calcium carbonate (CaCO3) was converted into molecular weight to calculate the amount of fixed carbon dioxide. As shown in Table 3, the amount of fixed carbon dioxide per 1 m3 of sample A was 42.30 kg. 3 The amount of carbon dioxide fixed per 1 m of sample B was 19.98 kg. 3 The amount of carbon dioxide fixed per unit was 18.61 kg.

[0024] [Table 3]

[0025] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and each of the above-described components can be modified as appropriate within the scope of the invention. For example, the use of the carbon dioxide fixing material is not limited to mortar aggregate. In the above embodiment, the hydraulic composition is mortar, but the hydraulic composition may be concrete. When the hydraulic composition is concrete, fine aggregate and coarse aggregate are used as aggregates.

[0026] Furthermore, when producing mortar or concrete, different mixers may be used in the primary mixing step S10 and the secondary mixing step S20. Furthermore, in the above embodiment, the case of producing mortar has been described, but the carbon dioxide fixing material may be produced (only the primary mixing step S10 is performed), stored as is, and then used as aggregate. The aggregate added in the stage of producing the carbon dioxide fixing material may be either fine aggregate or coarse aggregate, or may contain both fine aggregate and coarse aggregate. The form of the carbon dioxide fixing material is not limited to granular.

[0027] In the above embodiment, cement is used as the binder (primary binder and secondary binder). However, the binder may include at least one of blast furnace slag, expansive additive, slaked lime, quicklime, fly ash, and Portland cement. In other words, cement need not be used as the binder. For example, the formulation shown in Table 4 can be used as a blending mix when cement is not used as the binder. Because the slaked lime contained in the binder in the environmentally friendly blending mix shown in Table 2 contains a high calcium content, calcium carbonate (CaCO3) is more likely to be produced than when cement is used as the binder. (General cement contains 60% quicklime (CaO), while slaked lime contains only calcium hydroxide (Ca(OH)2) and contains 99% or more quicklime (CaO).) Although calcium (Ca) in cement forms compounds with aluminum (Al) and silicon (Si), carbon dioxide (CO2) could be adsorbed and fixed when a carbon dioxide fixation material was produced using cement. Therefore, it is believed that CO2 can be adsorbed and fixed even when a carbon dioxide fixation material is produced using slaked lime as the binder.

[0028] [Table 4]

[0029] In the above embodiment, in the aggregate coating step S12, a binder is added to a mixture of water and fine aggregate, and the mixture is kneaded while gas is injected and mixed into the mixer. However, the gas may be injected and mixed into the mixer after a paste is produced by kneading. In addition, in the above embodiment, the primary aggregate S1 and primary water W1 are mixed for a predetermined time in the water-aggregate mixing step S11, and then the primary binder C1 is added to the mixer in the aggregate coating step S12, and mixing is carried out for a predetermined time. However, the timing of adding the primary binder C1 is not limited, and for example, the primary aggregate S1, primary water W1, and primary binder C1 may be added to the mixer at the same time.

[0030] Furthermore, the gas is not limited to any gas containing carbon dioxide, and includes, for example, not only the atmosphere, but also carbon dioxide gas with a higher carbon dioxide content than the atmosphere, liquefied carbon dioxide gas, exhaust gas, etc. In the above embodiment, an admixture is mixed in, but the admixture may be used as needed. The admixture may be any admixture that satisfies JIS A 6204. In the above embodiment, the cement of the primary binder is mixed as an outer portion, but it may be mixed as an inner portion. In the above embodiment, the primary water is added as an internal proportion, but the primary water may be added as an external proportion. The aggregate may be recovered from washing wastewater generated when washing mixer trucks or the like in a concrete plant or the like. Furthermore, the water used may be recovered water, supernatant water, sludge water, etc. recovered from washing wastewater generated when washing mixer trucks or the like in concrete plants or the like. The binder may be made from calcium-containing construction or non-construction by-products or calcium-containing construction or non-construction waste materials.

[0031] The results of confirming the amount of fixed CO2 in concrete produced by the method for producing a hydraulic composition of the present invention are shown below. In the above embodiment (Example 1), the primary binder was mixed in an amount that was an exclusive proportion. However, in the following (Examples 2 to 4), the total amount of the primary binder and the secondary binder was 1 m 3 of the mortar mix design. 3 The amount of binder to be mixed per unit (partial mix).

[0032] Example 2 In Example 2, ordinary Portland cement was used as the binder. The mix proportion of the concrete in Example 2 is shown in Table 5. The materials used are shown in Table 6. As shown in Table 5, in this test, the cement content in the primary mixing was 10%. In this test, as shown in Figure 4(a), primary fine aggregate S1 and primary coarse aggregate G1 were added in the primary mixing step S10, and secondary fine aggregate S2 and secondary coarse aggregate G2 were added in the secondary mixing step S20. In Example 2, cement was used as the binder, and the water-cement ratio was 36% (sample C1), 45% (sample C2), and 55% (sample C3). 3 The amount of carbon dioxide fixed in the

[0033] [Table 5]

[0034] [Table 6]

[0035] The binder is not limited to ordinary Portland cement, and may be one or more selected from, for example, high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, blast-furnace cement (types A to C), fly ash cement (types A to C), silica cement (types A to C), ecocement, etc. The fine aggregate is not particularly limited, and one or more types selected from mountain sand, river sand, sea sand, crushed sand, silica sand, lime sand, and the like can be used. The coarse aggregate is not particularly limited, and one or more types selected from mountain gravel, river gravel, sea gravel, and the like can be used. As the admixture, known materials may be used, such as separation reducing agents, water reducing agents, antifoaming agents, setting retarders, setting accelerators, air-entraining agents, air-entraining water reducing agents, etc. The water is not limited to tap water, and for example, sludge water or the like can be used.

[0036] First, 1 m of mortar for each sample 3 The amount of carbon dioxide fixed relative to the amount of carbon dioxide fixed will be explained. Table 7 shows the results of thermogravimetric analysis performed on mortar 12 minutes after the primary mixing. In Example 2, the mortar was stirred for 12 minutes during the 12 minutes after the primary mixing. As shown in Table 7, the carbon dioxide (CO2) percentages (Sample C1: 3.07%, Sample C2: 2.55%, Sample C3: 2.09%) were calculated. The obtained values ​​were converted into molecular weights to calculate the calcium carbonate (CaCO3) content (Sample C1: 7.37%, Sample C2: 6.07%, Sample C3: 5.05%).

[0037] [Table 7]

[0038] Next, the amount of calcium carbonate (CaCO3) is calculated. 3 The amount of calcium carbonate (CaCO3) per 1 m of samples C1, C2, and C3 is calculated by multiplying the total mass of cement and fine aggregate at the time of primary mixing by the calcium carbonate (CaCO3) content. 3 The amount of fixed CO2 per unit is 7.2 kg / m 3 , 5.9 kg / m 3 , 4.9 kg / m 3 It was.

[0039] [Table 8]

[0040] Example 3 In Example 3, ordinary Portland cement was used as the binder, as in Example 2. The mix proportions of the concrete in Example 3 are shown in Table 9. The materials used were the same as those in Example 2 (see Table 6). In Example 3, as shown in Table 9, the primary mixing cement ratio was 12.5%, and the water-cement ratio was 36% (sample D1), 45% (sample D2), or 55% (sample D3). In addition, sludge water was used to achieve a primary mixing cement ratio of 12.5% ​​and a water-cement ratio of 55% (sample D4). In addition, the primary mixing cement ratio was 10% and a water-cement ratio of 55% (sample D5). 3 The amount of carbon dioxide fixed in the slurry was confirmed. In Example 3, as shown in Fig. 4(b), only fine aggregate S1 was added in the primary mixing step S10, and coarse aggregate G was added in the secondary mixing step S20. Note that the addition of fine aggregate may be performed only in the primary mixing step S10.

[0041] [Table 9]

[0042] First, 1 m of mortar for each sample 3 The amount of carbon dioxide immobilized relative to the sample will be explained. Table 10 shows the results of thermogravimetric analysis performed on mortar 12 minutes after the primary mixing. In Example 3, the mortar was stirred for 12 minutes during the 12 minutes after the primary mixing. As shown in Table 10, the carbon dioxide (CO2) percentages (Sample D1: 4.63%, Sample D2: 4.24%, Sample D3: 3.83%, Sample D4: 3.55%, Sample D5: 3.98%) were calculated. The obtained values ​​were converted to molecular weight to calculate the calcium carbonate (CaCO3) content (Sample D1: 10.94%, Sample D2: 10.05%, Sample D3: 9.12%, Sample D4: 8.37%, Sample D5: 9.42%).

[0043] [Table 10]

[0044] Next, calculate the amount of calcium carbonate (CaCO3).3 The results of calculations of the amount of calcium carbonate (CaCO3) per 1 m are shown below. The mass (kg) of calcium carbonate (CaCO3) is calculated by multiplying the total mass of cement and fine aggregate at the time of primary mixing by the content of calcium carbonate (CaCO3). As shown in Table 11, the mass of calcium carbonate (CaCO3) per 1 m of samples D1, D2, D3, D4, and D5 is 3 The amount of fixed CO2 per unit was 10.2 kg, 9.3 kg, 8.3 kg, 7.6 kg, and 6.8 kg, respectively.

[0045] [Table 11]

[0046] Next, the compressive strength of the test specimens manufactured from the concrete after the secondary mixing (secondary mixing step S20) was measured. The measurement results are shown in Figure 5. Compressive strength measurements were performed on samples D3 and D4 at ages of 7 days and 28 days. In addition, as comparative example D, the compressive strength of concrete was measured in a case where the concrete had the same mix as sample D3 but no carbon dioxide-containing gas was supplied in the aggregate coating step S12. As shown in Figure 5, neither sample D3 nor D4 showed a decrease in strength compared to comparative example D.

[0047] Example 4 In Example 4, tests were conducted on environmentally friendly concrete that did not use ordinary Portland cement as a binder. The mix proportions of the concrete in Example 4 are shown in Table 12. Table 13 shows the materials used. In Example 4, as shown in FIG. 4(a), primary fine aggregate S1 and primary coarse aggregate G1 were added in the primary mixing step S10, and secondary fine aggregate S2 and secondary coarse aggregate G2 were added in the secondary mixing step S20. As shown in Table 12, the results were analyzed for 1 m of each of the following samples: sample E1, in which the primary mixing binder proportion was 10% and the water-cement ratio was 36%, sample E2, in which sludge water was used in the primary mixing step and the water-cement ratio was 36%, and sample E3, in which the primary mixing binder proportion was 20% and the water-cement ratio was 36%. 3 The amount of carbon dioxide fixed in the

[0048] [Table 12]

[0049] [Table 13]

[0050] It is desirable to use ground granulated blast furnace slag used in JIS R5211 "Blast furnace cement" or ground granulated blast furnace slag conforming to JISA6206 "Blast furnace slag for concrete." It is desirable to use slaked lime that conforms to JIS R9001 "Industrial Lime". For example, the expansive material specified in JISA6202 "Expansive material for concrete" may be used. The fine limestone powder must meet JISA5008. The admixture must meet JISA6204.

[0051] First, 1 m of mortar for each sample 3 The amount of carbon dioxide immobilized relative to the sample will be explained. Table 14 shows the results of thermogravimetric analysis performed on the mortar 30 minutes after the primary mixing. In Example 4, the mortar was stirred for 12 minutes during the 12-minute period after the primary mixing. As shown in Table 14, the carbon dioxide (CO2) percentages (sample E1: 1.05%, sample E2: 2.61%, sample E3: 2.02%) were calculated. The obtained values ​​were converted into molecular weights to calculate the calcium carbonate (CaCO3) content (sample E1: 2.48%, sample E2: 6.08%, sample E3: 4.73%).

[0052] [Table 14]

[0053] Next, calculate the amount of calcium carbonate (CaCO3). 3The results of calculations of the amount of calcium carbonate (CaCO3) per 1 m are shown below. The mass (kg) of calcium carbonate (CaCO3) is calculated by multiplying the total mass of the binder and the mass of the fine aggregate at the time of primary mixing by the content of calcium carbonate (CaCO3). As shown in Table 15, the mass of calcium carbonate (CaCO3) per 1 m of samples E1, E2, and E3 is 3 The amounts of fixed CO2 per m3 of samples E1, E2, and E3 were 1.1 kg, 4.9 kg, and 2.7 kg, respectively. 3 The amount of fixed CO2 per unit was calculated by subtracting the amount of primary mixed limestone fine powder.

[0054] [Table 15]

[0055] Next, the compressive strength of the specimens manufactured using the concrete after the secondary mixing (secondary mixing step S20) was measured. The measurement results are shown in Figures 6 to 8. Compressive strength measurements were performed on Samples C1 and E1 at ages of 7 days (Figure 6), 14 days (Figure 7), and 28 days (Figure 8). The compressive strengths were also measured for concrete with the same mix as Sample C1 but without the supply of carbon dioxide-containing gas in the aggregate coating step S12 (Comparative Example C) and concrete with the same mix as Sample E1 but without the supply of carbon dioxide-containing gas in the aggregate coating step S12 (Comparative Example E). As shown in Figures 6 to 8, Sample C1 had comparable compressive strengths to Comparative Example C at ages of 7, 14, and 28 days. Furthermore, Sample E1 had compressive strengths equal to or greater than those of Comparative Example E at ages of 7 and 14 days, as shown in Figures 6 and 7, and comparable compressive strengths at age 28 days, as shown in Figure 8.

[0056] Example 5 In Example 5, tests were conducted on environmentally friendly concrete that did not use ordinary Portland cement as a binder. As in Example 4, the primary binder was mixed in an internal proportion. The concrete mix of Example 5 is shown in Table 16. The materials used were the same as those used in Example 4 (see Table 13). In Example 5, as shown in Table 16, for sample F1, in which the internal proportion of the primary binder was 10% and the water-cement ratio was 36%, and sample F2, in which the internal proportion of the primary binder was 10% and the water-cement ratio was 55%, 1 m of each sample was used. 3 The amount of fixed carbon dioxide per unit was confirmed. In this test, as shown in Figure 4(b), only fine aggregate S1 was added in the primary mixing step S10, and coarse aggregate G was added in the secondary mixing step S20.

[0057] [Table 16]

[0058] First, 1 m of mortar for each sample 3 The amount of carbon dioxide fixed relative to the amount of carbon dioxide fixed will be explained. Table 17 shows the results of thermogravimetric analysis performed on the mortar 30 minutes after the primary mixing. In Example 3, the mortar was stirred for 12 minutes within 12 minutes after the primary mixing. As shown in Table 17, the carbon dioxide (CO2) ratio (sample F1: 1.53%, sample F2: 1.45%) was calculated. The obtained values ​​were converted into molecular weight to calculate the calcium carbonate (CaCO3) content (sample F1: 3.63, sample F2: 3.44).

[0059] [Table 17]

[0060] Next, the amount of calcium carbonate (CaCO3) is calculated. 3The results of calculations of the amount of calcium carbonate (CaCO3) per 1 m are shown below. The mass (kg) of calcium carbonate (CaCO3) is calculated by multiplying the total mass of the binder and the mass of the fine aggregate during the primary mixing by the calcium carbonate (CaCO3) content. As shown in Table 18, the mass of 1 m of samples F1 and F2 is 3 The amount of fixed CO2 per 1 m of samples F1 and F2 was 2.3 kg and 1.4 kg, respectively. 3 The amount of fixed CO2 per unit was calculated by subtracting the amount of primary mixed limestone fine powder.

[0061] [Table 18] [Explanation of symbols]

[0062] S Fine aggregate P Paste

Claims

1. Aggregate and A carbon dioxide fixing material comprising: a paste that coats the aggregate; The paste is a mixture of a binder for a hydraulic composition and water, and carbon dioxide in gas supplied when the aggregate, the water, and the binder are kneaded is fixed in the paste.

2. Coarse aggregate; and mortar covering the coarse aggregate, The mortar is a mixture of a binder for a hydraulic composition, water, and fine aggregate, and is characterized in that carbon dioxide in gas supplied when the coarse aggregate, the water, the binder, and the fine aggregate are kneaded is fixed.

3. A method for producing a carbon dioxide fixation material by mixing aggregate, water, and a binder for a hydraulic composition in a mixer, Supplying a gas containing carbon dioxide into the mixer; A method for producing a carbon dioxide fixation material, comprising fixing the carbon dioxide in a paste that is a mixture of the binder and the water, and coating the aggregate with the paste.

4. A method for producing a carbon dioxide fixation material by mixing coarse aggregate, fine aggregate, water, and a binder for a hydraulic composition in a mixer, Supplying a gas containing carbon dioxide into the mixer; A method for producing a carbon dioxide fixation material, comprising fixing the carbon dioxide in mortar, which is a mixture of the binder, the water, and the fine aggregate, and coating the coarse aggregate with the mortar.

5. a primary kneading step of mixing aggregate, primary water, and a primary binder in a mixer and coating the aggregate with a primary paste that is a mixture of the primary water and the primary binder, thereby producing a carbon dioxide fixing material; a secondary kneading step of kneading the carbon dioxide fixing material, secondary water, and a secondary binder to produce a hydraulic composition, A method for producing a hydraulic composition, characterized in that in the primary mixing step, a gas containing carbon dioxide is supplied into the mixer, and the carbon dioxide contained in the gas is fixed in the primary paste.

6. The amount of the aggregate is 1 m ３ 6. The method for producing a hydraulic composition according to claim 5, wherein the amount of aggregate per unit area is a part of the amount of aggregate per unit area, and the remaining amount of aggregate is kneaded in the secondary kneading step.

7. a primary kneading step of mixing coarse aggregate, fine aggregate, primary water, and a primary binder in a mixer and coating the coarse aggregate with primary mortar, which is a mixture of the fine aggregate, the primary water, and the primary binder, to produce a carbon dioxide fixing material; a secondary kneading step of kneading the carbon dioxide fixing material, secondary water, and a secondary binder to produce a hydraulic composition, A method for producing a hydraulic composition, characterized in that in the primary mixing step, a gas containing carbon dioxide is supplied into the mixer, and the carbon dioxide contained in the gas is fixed in the primary mortar.

8. The amount of the coarse aggregate is 1 m ３ 8. The method for producing a hydraulic composition according to claim 7, wherein the amount of coarse aggregate per unit area is a part of the amount of coarse aggregate per unit area, and the remaining amount of coarse aggregate is kneaded in the secondary kneading step.

9. The amount of the fine aggregate is 1 m ３ 8. The method for producing a hydraulic composition according to claim 7, wherein the amount of fine aggregate per unit area is a part of the amount of fine aggregate per unit area, and the remaining amount of fine aggregate is kneaded in the secondary kneading step.

10. The total amount of the primary water and the secondary water is 1 m ３ The method for producing a hydraulic composition according to any one of claims 5 to 9, wherein the amount of water blended is per unit weight.

11. The amount of the secondary binder is 1 m ３ The method for producing a hydraulic composition according to any one of claims 5 to 9, wherein the blending amount of binder is per unit weight.

12. The total amount of the primary binder and the secondary binder is 1 m ３ The method for producing a hydraulic composition according to any one of claims 5 to 9, wherein the blending amount of binder is per unit weight.

13. The amount of the secondary water is 1 m ３ The method for producing a hydraulic composition according to any one of claims 5 to 9, wherein the amount of water blended is per unit weight.

14. An apparatus for producing a carbon dioxide fixation material used in the method for producing a carbon dioxide fixation material according to claim 3 or 4, comprising: a mixer for mixing aggregate, water, and a binder for a hydraulic composition; and a carbon dioxide supply means for supplying a gas containing carbon dioxide into the mixer.

15. A hydraulic composition manufacturing apparatus used in a method for manufacturing a hydraulic composition according to any one of claims 5 to 8, a mixer for mixing aggregate, water, and a binder for a hydraulic composition; and a carbon dioxide supply means for supplying a gas containing carbon dioxide into the mixer.

16. A hydraulic composition manufacturing apparatus as described in Claim 15, characterized in that the carbon dioxide supply means supplies carbon dioxide into the mixer while the aggregate, the water, and the binder are placed in the mixer.

17. A hydraulic composition manufacturing apparatus as described in Claim 15, characterized in that it is provided with a lid that closes the mixer.

18. A mixer for mixing aggregate, water, and a binder for a hydraulic composition; and a carbon dioxide supply means for supplying a gas containing carbon dioxide into the mixer.

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