Stabilized concrete sludge water and method for stabilizing concrete sludge water
Stabilized concrete sludge water, achieved through carbonation with controlled water-to-carbonate ratios and surface areas, addresses hardening issues and carbon dioxide fixation, enabling long-term storage and efficient use in concrete production.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TAIHEIYO CEMENT CORP
- Filing Date
- 2025-01-17
- Publication Date
- 2026-07-30
AI Technical Summary
Concrete sludge water hardens over time due to cement hydration, making it difficult to store and use without stabilizers, and existing methods do not effectively address carbon dioxide emissions.
Stabilized concrete sludge water is produced by carbonating sludge solids with carbon dioxide, maintaining a specific water-to-carbonate ratio and BET surface area, allowing long-term storage without stabilizers and fixing carbon dioxide into the mixture.
The stabilized sludge water remains non-hardened for extended periods, facilitating its use as mixing water and reducing carbon dioxide emissions by incorporating it into hydraulic compositions.
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Abstract
Description
[Technical Field]
[0001] The present invention relates to stabilized concrete sludge water and a method for stabilizing concrete sludge water. [Background technology]
[0002] Concrete is mixed and used at construction sites, but sometimes there is leftover concrete that is not used up. Assuming that the rate of leftover concrete (hereinafter also referred to as "returned concrete") relative to the domestic shipment volume of ready-mixed concrete is about 2%, the annual amount of returned concrete generated is about 1 million m³. 3 The above is the estimated figure. One method for processing returned concrete is to use the sludge water, which is obtained by removing coarse and fine aggregates from the wastewater generated during the washing of the returned concrete, as part of the mixing water for the concrete. JIS A 5308:2024 (Ready-Mixed Concrete) states that the above-mentioned sludge water can be used as mixing water for concrete up to 6% by mass in terms of solid content (the ratio of solid content in the sludge water to cement in the concrete). Furthermore, the dewatered cake from the sludge water is often used as part of the roadbed improvement material, or disposed of in landfills. Patent Document 1 describes a method for using ready-mix concrete sludge water as mixing water, to which a setting retarder containing setting retarder components is added, and the method comprises at least the following steps: measurement step: Here, the ready-mix concrete sludge water is periodically measured to determine at least the concentrations of sulfate ions and setting retarder components; and determination step: Here, the determination of whether the ready-mix concrete sludge water is suitable for use is based on the measurement results.
[0003] On the other hand, reducing carbon dioxide emissions has become a crucial issue in order to curb global warming. Patent Document 2 describes a highly efficient manufacturing method for fixing CO2 to cement hydrate in a short time, which includes a CO2 injection step in which cement hydrate and water are placed in a container, and CO2 is injected into the container while stirring the mixture of cement hydrate and water, and in the CO2 injection step, the CO2 injection rate is 3600 kg / t·h or more and the CO2 injection amount is 600 kg / t or more, and this method fixes CO2 to cement hydrate. [Prior art documents] [Patent Documents]
[0004] [Patent Document 1] Japanese Patent Publication No. 2021-171982 [Patent Document 2] Japanese Patent Publication No. 2022-156508 [Overview of the project] [Problems that the invention aims to solve]
[0005] Because concrete sludge water contains cement, it gradually hardens through a reaction between cement and water. Therefore, when using concrete sludge water as mixing water, it is necessary to add a stabilizer containing a retarding component. Furthermore, it is difficult to store concrete sludge water for extended periods without it hardening. The object of the present invention is to provide concrete sludge water that can be prevented from hardening without the use of stabilizers, and that can fix carbon dioxide into concrete, a hydraulic composition containing concrete sludge water, and a method for stabilizing concrete sludge water. [Means for solving the problem]
[0006] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the above objective can be achieved by using stabilized concrete sludge water containing carbon dioxide from sludge solids and water, wherein the mass ratio of water to carbon dioxide from sludge solids is 60 to 15,000%, and have completed the present invention. In other words, the present invention provides the following [1] to [6]. [1] Stabilized concrete sludge water, characterized in that it contains carbon oxides of sludge solids and water, and the mass ratio of the water to the carbon oxides of the sludge solids is 60 to 15,000%. [2] The BET specific surface area of the carbon oxide in the above sludge solids is 5 to 100 m² 2 The stabilized concrete sludge water described in [1] above, which is / g. [3] A hydraulic composition comprising the stabilized concrete sludge water, cement, and aggregate described in [1] or [2] above.
[0007] [4] A method for producing a hydraulic composition, comprising mixing the stabilized concrete sludge water described in [1] or [2] above with cement and aggregate. [5] A method for stabilizing concrete sludge water, comprising a stabilization step of bringing the concrete sludge water into contact with a carbon dioxide-containing gas to carbonize at least a portion of the sludge solids contained in the concrete sludge water, thereby obtaining stabilized concrete sludge water containing carbon oxides of the sludge solids and water. [6] The concrete sludge water stabilization treatment method according to [5], further comprising a storage step of storing the stabilized concrete sludge water for 10 days or more after the stabilization treatment step. [Effects of the Invention]
[0008] The stabilized concrete sludge water of the present invention does not harden even without the presence of a stabilizer, eliminating the need to consider the effect of stabilizers on concrete and other materials. Furthermore, because it does not harden, it can be stored for a long period of time, and the concrete sludge water after long-term storage can be used as a mixing water and as a material for concrete and other materials. Furthermore, since carbon dioxide can be fixed within concrete and other materials, carbon dioxide emissions can be reduced. [Brief explanation of the drawing]
[0009] [Figure 1] It is a schematic diagram of a stabilization treatment system for concrete sludge water.
Mode for Carrying Out the Invention
[0010] The stabilized concrete sludge water of the present invention contains carbohydrates and water of sludge solids, and the mass ratio of water to carbohydrates of sludge solids is 60 to 15,000%. In this specification, "concrete sludge water" refers to the water obtained by removing coarse and fine aggregates from the fresh mortar adhering to transport vehicles, plant mixers, hoppers, etc., the remaining fresh concrete, and the drainage generated by washing the returned concrete in a concrete manufacturing plant. Also, "sludge solids" are the solids contained in concrete sludge water. Sludge solids can be recovered from concrete sludge water by concentrating the concrete sludge water and further drying the sludge in a state where it has lost its fluidity (for example, drying at 105 to 110 °C).
[0011] Concrete sludge water contains at least a part of cement hydrate as sludge solids. Cement hydrate is formed by the reaction (hydration) of cement and water. Examples of cement hydrate include 3CaO·Al2O3·3CaSO4·32H2O, 3CaO·Al2O3·CaSO4·12H2O, 3CaO·Al2O3·6H2O, 4CaO·Al2O3·14H2O, 3CaO·2SiO2·3H2O, Ca(OH)2, etc. The carbohydrate of sludge solids is obtained by carbonating at least a part of the cement hydrate contained in the sludge solids. Calcium carbonate is generated by carbonation. Here, in this specification, "carbonation" means absorbing and immobilizing carbon dioxide. When the concrete sludge water contains carbonates of sludge solids, even if no stabilizer is used, the solids in the concrete sludge water do not harden, so it can be stored for a long time and has excellent workability.
[0012] The mass ratio of water to the carbonates of sludge solids (expressed as a percentage of water / (carbonates of sludge solids)) contained in the stabilized concrete sludge water is 60 to 15,000%, preferably 70 to 12,000%, more preferably 100 to 11,000%, still more preferably 400 to 5,000%, and particularly preferably 600 to 2,000%. When the above mass ratio is less than 60%, the fluidity and workability of the concrete sludge water before carbonation and the stabilized concrete sludge water decrease. Also, when the above mass ratio exceeds 15,000%, it takes labor to adjust the moisture content when using the stabilized concrete sludge water as a material for a hydraulic composition. Examples of water include tap water, industrial water, supernatant water of fresh concrete, recovered water specified in "JIS A 5308:2024 (Ready-mixed Concrete)", etc.
[0013] The BET specific surface area of the carbonates of sludge solids is preferably 5 to 100 m 2 / g, more preferably 20 to 95 m 2 / g, still more preferably 30 to 90 m 2 / g, still more preferably 40 to 80 m 2 / g, particularly preferably 60 to 75 m 2 / g. If the above BET specific surface area is 5 m 2 / g or more, the strength development property of the hydraulic composition containing the stabilized concrete sludge water is further improved. If the above BET specific surface area is 100 m 2 / g or less, the fluidity before hardening of the hydraulic composition containing the stabilized concrete sludge water is further improved.
[0014] The pH of the stabilized concrete sludge water is preferably 5.0 to 9.5, more preferably 5.2 to 8.5, even more preferably 5.5 to 7.5, and particularly preferably 6.0 to 7.0. If the pH is 5.0 or higher, the time required to supply carbon dioxide-containing gas in the stabilization process (described later) for obtaining stabilized concrete sludge water is shortened, and the manufacturing efficiency is further improved. If the pH is 9.5 or lower, sufficient carbonation of the sludge solids occurs, making the stabilized concrete sludge water less prone to hardening and more stable. In addition, it becomes possible to store it for a long period of time while maintaining its non-hardened state.
[0015] The stabilized concrete sludge water of the present invention can be prepared by a stabilization treatment method that includes a stabilization treatment step, for example, in which at least a portion of the sludge solids contained in the concrete sludge water are carbonated by contacting the concrete sludge water with a carbon dioxide-containing gas, thereby obtaining stabilized concrete sludge water containing carbon oxides of the sludge solids and water. The following explains in detail. There are no particular limitations on the method for bringing concrete sludge water into contact with carbon dioxide-containing gas. For example, one method involves placing the concrete sludge water and carbon dioxide-containing gas in a carbonation tank such that the gas phase of the carbon dioxide-containing gas is positioned above the liquid phase of the concrete sludge water, thereby bringing the concrete sludge water and carbon dioxide-containing gas into contact. Furthermore, from the viewpoint of efficient carbonation, it is preferable to bring the concrete sludge water into contact with the carbon dioxide-containing gas while it is flowing.
[0016] Figure 1 is a schematic diagram showing an example of a stabilization treatment system 1 for stabilizing concrete sludge water and preparing stabilized concrete sludge water. Concrete sludge water 9 is contained in a storage tank 3 and a carbonation tank 2. The carbonation tank 2 is preferably sealed from the viewpoint of efficient carbonation. Concrete sludge water 9 is supplied from the storage tank 3 to the carbonation tank 2 via a sludge water supply pipe 6 using a pump 5. Carbon dioxide-containing gas is continuously supplied from a carbon dioxide supply device 7 to the carbonation tank 2 through a carbon dioxide supply passage 8, and the concrete sludge water 9 and carbon dioxide-containing gas come into contact in the carbonation tank 2. The concrete sludge water 9 is circulated by moving to the storage tank 3 via a sludge water circulation passage 4, and then being supplied again to the carbonation tank 2 from the sludge water supply pipe 6. Alternatively, a carbon dioxide supply means (not shown) for supplying carbon dioxide-containing gas into the concrete sludge water may be installed, and carbon dioxide-containing gas may be supplied into the concrete sludge water.
[0017] In the stabilization process, the water-sludge solids ratio (the mass ratio of water to sludge solids expressed as a percentage) of the concrete sludge water varies depending on the target concentration of the concrete sludge water, but is preferably 60-800%, more preferably 100-500%, and particularly preferably 200-400%. If the water-sludge solids ratio is 60% or higher, workability is improved, and carbon dioxide can be stably absorbed and fixed into the concrete sludge water. If the water-sludge solids ratio is 800% or lower, the time required to sufficiently carbonate the sludge solids can be further shortened.
[0018] In the stabilization process, the carbon dioxide-containing gas supplied to the concrete sludge water may consist solely of carbon dioxide (carbonic acid gas), but from the viewpoint of ease of availability, it may also be a gas containing carbon dioxide and other gases (e.g., nitrogen). The proportion of carbon dioxide in the carbon dioxide-containing gas is preferably 5% by volume or more, more preferably 10% by volume or more, even more preferably 20% by volume or more, even more preferably 50% by volume or more, even more preferably 80% by volume or more, and particularly preferably 90% by volume or more. If this proportion is 5% by volume or more, the amount of carbon dioxide fixed in the concrete sludge water can be increased. In addition, the time required to sufficiently carbonate the sludge solids can be shortened. Examples of carbon dioxide-containing gases include liquefied carbon dioxide, exhaust gas generated in the cement manufacturing process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in the steelmaking process (carbon dioxide concentration: approximately 20% by volume), exhaust gas generated in the thermal power generation process (carbon dioxide concentration: approximately 10% by volume), or gas separated and recovered from these exhaust gases (carbon dioxide concentration: approximately 100% by volume).
[0019] In the stabilization process, carbonation is carried out until the pH of the stabilized concrete sludge water falls within the preferred range described above. Note that as carbonation of the sludge solids progresses, the pH of the stabilized concrete sludge water decreases. The time required to sufficiently carbonate the sludge solids varies depending on the mass ratio of water to sludge solids, the means of supplying carbon dioxide-containing gas, and the concentration of carbon dioxide in the carbon dioxide-containing gas supplied by said means. Therefore, it is preferable to determine the timing of the end of carbonation based on the measured pH value of the stabilized concrete sludge water.
[0020] A storage step may be provided after the stabilization treatment process, during which the stabilized concrete sludge water is stored for 10 days or more. The stabilized concrete sludge water obtained in the stabilization process does not harden even without a stabilizer, and can be used as a material (mixing water) for hydraulic compositions even after long-term storage (preferably 14 days or more, more preferably 20 days or more). Prior to the stabilization process, a first moisture adjustment step may be provided to adjust the amount of water contained in the concrete sludge water, from the viewpoint of making carbonation more efficient. Furthermore, after the stabilization process, a second moisture adjustment step may be provided to adjust the amount of stabilized concrete sludge water for the purpose of facilitating storage and adjusting the moisture content for use as a material (mixing water) for the hydraulic composition.
[0021] The hydraulic composition of the present invention comprises the stabilized concrete sludge water, cement, and aggregate described above. The cement used is not particularly limited and includes various types of Portland cement such as ordinary Portland cement, rapid-hardening Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as well as blended cements such as blast furnace cement, fly ash cement, and silica cement, and alumina cement and eco-cement. These may be used individually or in combination of two or more types.
[0022] The aggregate can consist of fine aggregate alone, or a combination of fine aggregate and coarse aggregate. Natural aggregate, artificial aggregate, or recycled aggregate can also be used. The fine aggregate is not particularly limited and includes, for example, river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, limestone aggregate, slag fine aggregate, lightweight fine aggregate, clinker fine aggregate, and CCU fine aggregate (fine aggregate with carbon dioxide fixed from one or more types selected from recycled aggregate, waste concrete, blast furnace slag, and steelmaking slag). These may be used individually or in combination of two or more types.
[0023] The coarse aggregate is not particularly limited and includes, for example, river gravel, mountain gravel, land gravel, sea gravel, crushed stone, limestone aggregate, slag coarse aggregate, lightweight coarse aggregate, clinker coarse aggregate, and CCU coarse aggregate (coarse aggregate with carbon dioxide fixed from one or more types selected from recycled aggregate, waste concrete, blast furnace slag, and steelmaking slag). These may be used individually or in combination of two or more types.
[0024] Hydraulic composition 1m 3The mass of the powder material (total of carbon oxides, cement, and various admixtures optionally added to the stabilized concrete sludge) per unit is preferably 230 to 1,400 kg, more preferably 240 to 1,000 kg, even more preferably 250 to 800 kg, even more preferably 260 to 500 kg, and particularly preferably 270 to 400 kg. If the above mass is 230 kg or more, the strength development of the hydraulic composition is further improved. If the above mass is 1,400 kg or less, the heat of hydration of the hydraulic composition can be further reduced. Furthermore, the proportion of sludge solids' carbon dioxide in the total 100% by mass of cement and sludge solids' carbon dioxide is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and particularly preferably 3 to 15% by mass. If the above proportion is 1% by mass or more, the effective utilization of concrete sludge water can be further promoted. In addition, more carbon dioxide can be fixed into the hydraulic composition (mortar or concrete). If the above proportion is 40% by mass or less, the strength development of the hydraulic composition can be further improved.
[0025] Hydraulic composition 1m 3 The mass of aggregate per unit (including fine aggregate and coarse aggregate, if present) is preferably 700 to 2,400 kg, more preferably 1,000 to 2,200 kg, even more preferably 1,200 to 2,000 kg, and particularly preferably 1,400 to 1,800 kg. If the above mass falls within the above numerical range, the strength development of the hydraulic composition is further improved, and the shrinkage rate of the hardened body is reduced. The fine aggregate ratio of the hydraulic composition is preferably 40-55%, more preferably 42-53%, and particularly preferably 44-51%, from the viewpoint of workability, moldability, etc. The fine aggregate ratio refers to the volume ratio of fine aggregate to the total amount of fine aggregate and coarse aggregate.
[0026] Furthermore, the hydraulic composition may optionally contain various admixtures such as fly ash, silica fume, and blast furnace slag powder, as well as various admixtures such as AE agents, cement dispersants (water-reducing agents, AE water-reducing agents, high-performance water-reducing agents, or high-performance AE water-reducing agents), defoaming agents, and shrinkage-reducing agents, within limits that do not hinder the objectives of the present invention. The content of various admixtures in the hydraulic composition is preferably 30% by mass or less, more preferably 10% by mass or less.
[0027] An example of a method for producing the hydraulic composition of the present invention is a method of producing the hydraulic composition by mixing stabilized concrete sludge water, cement, and aggregate. The mixing method is not particularly limited; the cement and aggregate may be mixed first, and then the resulting mixture may be mixed with stabilized concrete sludge water, or each material may be mixed simultaneously. Furthermore, in order to adjust the amount of water contained in the hydraulic composition, water may be added and mixed separately from the water contained in the stabilized concrete sludge water. [Examples]
[0028] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement A; manufactured by Taiheiyo Cement Corporation, ordinary Portland cement, density: 3.16 g / cm³ 3 (2) Cement B; manufactured by Taiheiyo Cement Corporation, blast furnace cement type B, density: 3.04 g / cm³ 3 (3) Concrete sludge water A; obtained by carbonizing concrete sludge water, the BET specific surface area of the dried carbon oxide powder of the sludge solids (obtained by drying concrete sludge water at 105°C until a constant weight is reached) is 62.3 m². 2 It is / g and has a density of 2.58 g / cm³. 3 that which is (4) Concrete sludge water B; obtained by carbonizing concrete sludge water, the BET specific surface area of the dried powder of carbon oxides from the sludge solids (obtained by drying concrete sludge water at 105°C until a constant weight is reached) is 48.0 m² 2 It is / g and has a density of 2.59 g / cm³. 3 that which is (5) Concrete sludge water C (different from the concrete sludge water used in concrete sludge water A and concrete sludge water B); the BET specific surface area of the dried sludge solid powder (obtained by drying concrete sludge water at 105°C until a constant weight is reached) is 23.7 m². 2 It is / g and has a density of 3.05 g / cm³. 3 that which is (6) Fine aggregate; mountain sand, surface dry density: 2.56g / cm 3 (7) Coarse aggregate; hard sandstone, crushed stone 2005, surface dry density 2.62 g / cm³ 3 , Actual rate: 60.8% (8) High-performance AE water-reducing agent A (standard type); manufactured by Pozzolith Solutions, product name "Master Glenium SP8SV" (9) High-performance AE water-reducing agent B (delayed type); manufactured by Pozzolith Solutions, product name "MasterEase 8050" (10) AE agent; manufactured by Pozzolith Solutions, product name "MasterAir 202A" (11) Stabilizer; manufactured by Pozzolith Solutions, product name "Masterset 110CLN" The preparation methods for concrete sludge water A and B will be described later.
[0029] [Preparation of concrete sludge water A] Further water was added to the concrete sludge water to adjust the mass ratio of sludge solids to water to 1:3, and then the mixture was kneaded for 120 seconds using a hand mixer to prepare the concrete sludge water. Using the stabilization treatment system 1 shown in Figure 1, concrete sludge water 9 was placed in a carbonation tank 2, which was supplied with carbon dioxide-containing gas (carbon dioxide concentration: 99.5 vol%) from a carbon dioxide supply device 7 through a carbon dioxide supply path 8. A pump 5 was used to circulate the concrete sludge water 9 between the carbonation tank 2 and the storage tank 3, while carbonizing the sludge solids in the concrete sludge water 9. The pH of the concrete sludge water (stabilized concrete sludge water) at the end of the stabilization (carbonation) treatment was 6.5.
[0030] [Preparation of concrete sludge water B] Concrete sludge water was prepared in the same manner as in the preparation of concrete sludge water A, except that a different type of concrete sludge water was used. The pH of the concrete sludge water (stabilized concrete sludge water) at the end of the stabilization (carbonation) treatment was 6.5.
[0031] [Examples 1-4] Water was added to the types of concrete sludge water (stabilized) shown in Table 1 to adjust the mass ratio of water to sludge solids (carbon oxides) contained in the concrete sludge water (indicated as "liquid-solid ratio" in Table 2) to the values shown in Table 1. After this, the water was stored by standing in a storage tank. The condition of the concrete sludge water was visually inspected after the storage period shown in Table 1, and the presence or absence of hardening was evaluated. [Comparative Examples 1-5] The types and quantities of concrete sludge water (untreated) and stabilizers shown in Table 1 were mixed with water to adjust the mass ratio of water to sludge solids in the concrete sludge water to the values shown in Table 1. After adjustment, the mixture was stored by standing in a storage tank. The condition of the concrete sludge water was visually inspected after the storage period shown in Table 1, and the presence or absence of hardening was evaluated. The results are shown in Table 1.
[0032] [Table 1]
[0033] Table 1 shows that in Examples 1-4, no hardening of the concrete sludge water was observed even after 21 days of storage. On the other hand, hardening of the concrete sludge water was observed in Comparative Examples 1-5.
[0034] [Examples 5-8] Concrete was manufactured using the types and quantities of materials shown in Tables 2 and 3. Specifically, cement, fine aggregate, and coarse aggregate were placed in a mixer and dry-mixed for 15 seconds. Then, a mixture of concrete sludge water, a high-performance AE water-reducing agent, and an AE agent, which had been pre-mixed, was placed in the mixer and mixed for 2 minutes in Examples 5 and 6, and for 6 minutes in Examples 7 and 8. Next, the mixed material adhering to the inner wall of the mixer was scraped off, and then the mixture was further mixed for 1 minute in Examples 5 and 6, and for 2 minutes in Examples 7 and 8, to produce a hydraulic composition (concrete). Furthermore, the concrete sludge water (referred to as "sludge water" in Table 2) used was prepared by adjusting the liquid-to-solid ratio (the mass ratio of water to carbon oxide or sludge solids in the sludge) of the types of concrete sludge water shown in Table 2 to 100%, allowing it to stand for 24 hours, and then adding water until the liquid-to-solid ratio reached the values shown in Table 2. In Table 2, the unit amount of water includes the solids in the concrete sludge water.
[0035] The physical properties of the obtained hydraulic composition were measured or evaluated according to the following methods. (1) Measurement of slump The slump of the hydraulic composition was measured in accordance with "JIS A 1101:2020 (Slump Test Method for Concrete)". The target value was set at 18 ± 2.5 cm. (2) Measurement of air volume The air content of the hydraulic composition was measured in accordance with "JIS A 1128:2019 (Test method for air content of flash concrete by pressure - Air chamber pressure method)". The target value was set at 4.5 ± 1.5%. (3) Measurement of setting time The setting time of the concrete was measured in accordance with "JIS A 1147:2019 (Test method for concrete setting time)". (4) Measurement of compressive strength The compressive strength of concrete at 1 or 3 days of age was measured in accordance with "JIS A 1108:2018 (Compression Test Method for Concrete)". Curing was performed by underwater curing at 20°C.
[0036] [Comparative Examples 6-9] Concrete was manufactured using the types and quantities of materials shown in Tables 2 and 3. Specifically, cement, fine aggregate, and coarse aggregate were placed in a mixer and dry-mixed for 15 seconds. Then, a mixture of concrete sludge water, a high-performance AE water-reducing agent, and an AE agent, which had been pre-mixed, was placed in the mixer and mixed for 2 minutes in Comparative Examples 6 and 7, and for 6 minutes in Comparative Examples 8 and 9. Next, the mixed material adhering to the inner wall of the mixer was scraped off, and then the mixture was further mixed for 1 minute in Comparative Examples 6 and 7, and for 2 minutes in Comparative Examples 8 and 9, to produce a hydraulic composition (concrete). Furthermore, the concrete sludge water (referred to as "sludge water" in Table 2) was prepared by adding the amount of stabilizer shown in Table 2 to the concrete sludge water of the type shown in Table 2, mixing it, adjusting the liquid-to-solid ratio to 100%, allowing it to stand for 24 hours, and then adding water until the liquid-to-solid ratio reached the values shown in Table 2. The physical properties of the hydraulic composition were measured in the same manner as in Example 5. The results for each are shown in Table 3.
[0037] [Table 2]
[0038] [Table 3]
[0039] Table 2 shows that the slump, setting time, and compressive strength of Examples 5-8 are comparable to those of Comparative Examples 6-8, respectively. [Explanation of symbols]
[0040] 1. Stabilization Processing System 2 Carbonation tanks 3. Storage tanks 4. Sludge water circulation path 5 pumps 6. Sludge water supply pipe 7. Carbon dioxide supply device 8. Carbon dioxide supply channels 9. Concrete sludge water
Claims
1. The sludge contains carbon dioxide and water as solid components. A stabilized concrete sludge water characterized in that the mass ratio of the above water to the above sludge solid carbon dioxide is 60 to 15,000%.
2. The BET specific surface area of the carbon oxide in the above sludge solids is 5 to 100 m². ２ The stabilized concrete sludge water according to claim 1, wherein the amount is / g.
3. A hydraulic composition comprising stabilized concrete sludge water, cement, and aggregate according to claim 1 or 2.
4. A method for producing a hydraulic composition, comprising mixing the stabilized concrete sludge water described in claim 1 or 2 with cement and aggregate to produce a hydraulic composition.
5. A method for stabilizing concrete sludge water, A stabilization process to obtain stabilized concrete sludge water containing carbon dioxide and water by bringing the above-mentioned concrete sludge water into contact with a carbon dioxide-containing gas, thereby carbonizing at least a portion of the sludge solids contained in the above-mentioned concrete sludge water. A method for stabilizing concrete sludge water, characterized by including the following:
6. The concrete sludge water stabilization treatment method according to claim 5, further comprising a storage step of storing the stabilized concrete sludge water for 10 days or more after the stabilization treatment step described above.