Additive for carbonation-promoting hydraulic composition, hydraulic composition cured body containing same, and method for producing same

Abstract

The present invention is related to an additive to be used in a carbonation-promoting hydraulic composition, the additive being composed of organic fibers with a water-repellent treatment agent adhered to the surface of the organic fibers. The adhesion amount of the water-repellent treatment agent to the organic fibers is preferably 0.01-3 mass% in terms of solid content (active ingredient). As a result, the present invention provides: an additive for a carbonation-promoting hydraulic composition capable of improving the carbon dioxide fixation property of a hydraulic composition cured body that can fix carbon dioxide; a hydraulic composition cement cured body containing the additive; and a method for producing the same.

Description

Additive for a carbonated hydraulic composition, a hardened hydraulic composition containing the same, and a method for producing the same.

[0001] The present invention relates to an additive for a carbonation-promoting hydraulic composition used in a hardened hydraulic composition capable of fixing carbon dioxide, a hardened carbonate-promoting hydraulic composition containing the same, and a method for producing the same.

[0002] Carbon dioxide (CO2) ２ CO2 is one of the greenhouse gases that raises the average temperature of the Earth. In recent years, the massive consumption of fossil fuels has led to CO2 emissions. ２ While the amount of CO2 is increasing, deforestation is causing CO2 emissions from plants. ２ Due to a decrease in absorption, etc., CO2 in the atmosphere ２ CO2 is increasing in concentration, and its impact on global warming is becoming a major problem. ２ By recovering, absorbing, storing, and fixing CO2 from the atmosphere, ２ Technologies have been developed to remove CO2, and one of them involves fixing carbon dioxide into cement-hardened materials such as concrete. ２ Technologies for fixing carbon dioxide are being investigated. For example, Patent Document 1 proposes a carbon dioxide-fixing concrete structure in which a concrete composition for forming a carbon dioxide-fixing molded body is kneaded with water, cement, admixtures, and aggregate, and contains at least one of alkali-degradable resin fine particles, organic fibers made of alkali-degradable resin, ultraviolet-degradable resin fine particles, and organic fibers made of ultraviolet-degradable resin, and after molding and hardening, the resin fine particles or organic fibers made of resin contained in the concrete composition are decomposed by alkali or ultraviolet light, forming a surface layer having voids useful for carbon dioxide fixation.

[0003] Japanese Patent Publication No. 2008-75391

[0004] However, the carbon dioxide-fixing concrete structure described in Patent Document 1 is required to have further improvements in its carbon dioxide-fixing properties.

[0005] To solve the above-mentioned conventional problems, the present invention provides an additive for a carbonation-promoting hydraulic composition that can enhance the carbon dioxide fixation ability of a hardened hydraulic composition capable of fixing carbon dioxide, a hardened hydraulic composition cement containing the same, and a method for producing the same.

[0006] The present invention relates to an additive for use in a carbonation-promoting hydraulic composition, wherein the additive is an organic fiber, and a water-repellent treatment agent is attached to the surface of the organic fiber.

[0007] The present invention also relates to an additive for use in a carbonation-promoting hydraulic composition, wherein the additive comprises a short fiber bundle of organic fibers, a water-repellent treatment agent, and a liquid containing water, the short fiber bundle is wetted with the liquid containing the water-repellent treatment agent and water, and the moisture content is 5% by mass or more and 60% by mass or less.

[0008] The present invention also relates to an additive for use in a carbonation-promoting hydraulic composition, wherein the additive comprises organic fibers and a water-repellent treatment agent attached to the surface of the organic fibers, wherein a portion of the organic fibers are bound together by the water-repellent treatment agent and the moisture content is less than 5% by mass.

[0009] The present invention also relates to a hardened hydraulic composition comprising the additive for the carbonation-promoting hydraulic composition, which has been cured by carbonation.

[0010] The present invention also relates to a method for producing fibers for a carbonation-promoting hydraulic composition, comprising step A of treating organic fibers with a water-repellent treatment agent.

[0011] The present invention provides an additive for a carbonation-promoting hydraulic composition that can enhance the carbon dioxide fixation properties of a hardened hydraulic composition, and a hardened carbonation-promoting hydraulic composition containing the same. According to the manufacturing method of the present invention, an additive for a carbonation-promoting hydraulic composition that can enhance the carbon dioxide fixation properties of a hardened hydraulic composition can be obtained.

[0012] The present inventors have intensively studied to solve the above-described problems. Fibers used in hardened bodies of hydraulic compositions such as cement hardened bodies are usually provided with a hydrophilic treatment agent due to their affinity with hydraulic materials such as cement materials. However, the present inventors have surprisingly found that by attaching a water-repellent treatment agent to the surface of organic fibers, CO ２ can be taken in from the outside of the cement molded product into the air and immobilized in the cement composition, and the carbon dioxide fixation ability of the carbonation-promoting hydraulic composition hardened body can be improved. This is presumably because the fiber surface of the organic fiber is water-repellent, so that the organic fiber easily entrains air bubbles, ensuring a flow path for air containing CO ２ and increasing the amount of CO ２ reacted (fixed). The additive for the hydraulic material may be an organic fiber having a water-repellent treatment agent attached to its surface, or an organic fiber in which a part of the organic fiber is aggregated by the water-repellent treatment agent, or a short fiber bundle of organic fibers moistened with a liquid containing the water-repellent treatment agent and water and having a predetermined moisture content. On the other hand, the carbon dioxide-immobilized concrete structure described in Patent Document 1 uses a structure in which resin fine particles or organic fibers made of resin contained in the concrete composition are decomposed by alkali or ultraviolet rays to form a surface layer portion having voids useful for carbon dioxide immobilization. In this case, however, it is difficult to control the degree of decomposition of the resin fine particles or organic fibers decomposed by alkali or ultraviolet rays, and the amount of carbon dioxide fixed in the concrete tends to be unstable. In addition, the strength of the fiber itself may be reduced due to decomposition by alkali or ultraviolet rays, which may cause a reduction in the physical properties of the concrete.

[0013] (Additive for carbonation-promoting hydraulic composition) The additive for the carbonation-promoting hydraulic composition is used in a carbonation-promoting hydraulic composition such as a cement composition that can immobilize carbon dioxide after curing. In the present specification, the "carbonation-promoting hydraulic composition" means a carbonation-promoting hydraulic composition that can react with carbon dioxide by calcium hydroxide, calcium silicate hydrate, etc. during curing and / or after curing and immobilize carbon dioxide in the hardened body. Specifically, cement compositions such as mortar and concrete can be mentioned.

[0014] In the first embodiment of the present invention, the additive for the carbonation-promoting hydraulic composition includes organic fibers and a water-repellent treatment agent attached to the surface of the organic fibers. In the second embodiment of the present invention, the additive for the carbonation-promoting hydraulic composition includes a short fiber bundle of organic fibers and a liquid containing a water-repellent treatment agent and water, wherein the short fiber bundle is wet with the liquid containing the water-repellent treatment agent and water, and has a moisture content of 5% by mass or more and 60% by mass or less. In the third embodiment of the present invention, the additive for the carbonation-promoting hydraulic composition includes organic fibers and a water-repellent treatment agent attached to the surface of the organic fibers, wherein a portion of the organic fibers is bundled by the water-repellent treatment agent, and has a moisture content of less than 5% by mass. In the following, unless otherwise specified, the descriptions of the organic fibers and the water-repellent treatment agent apply to the additive for the carbonation-promoting hydraulic composition of any of the first, second, and third embodiments. In this specification, if the moisture content of a short fiber bundle of organic fibers is 5% by mass or more, it means that the short fiber bundle of organic fibers is wet with a liquid containing a water-repellent treatment agent and water. In this specification, a short fiber bundle of organic fibers means that the fiber length of a single fiber is 50 mm or less.

[0015] The organic fibers preferably have a contact angle with water of 90° or more, more preferably 100° or more, even more preferably 110° or more, even more preferably 115° or more, and particularly preferably 120° or more. This results in high water repellency on the surface of the organic fibers, which repels moisture inherent at the interface with the interior of a hydraulic composition hardened body such as a cement hardened body, thus reducing CO ２ It is easy to secure an airflow path containing CO ２ The amount of reaction (immobilization) tends to increase. In this specification, the contact angle of organic fibers with water can be measured as described in the examples.

[0016] From the viewpoint of excellent water repellency, the aforementioned organic fibers preferably have a settling velocity of 4 minutes or more in water 50 mm deep, more preferably 5 minutes or more, and most preferably 10 minutes or more. Furthermore, the settling velocity of the aforementioned organic fibers after washing in water 50 mm deep is preferably 4 minutes or more, more preferably 5 minutes or more, and most preferably 10 minutes or more. In this specification, the settling velocity can be measured as described in the examples.

[0017] Examples of the organic fibers include synthetic fibers, semi-synthetic fibers, regenerated fibers, and natural fibers. Examples of synthetic fibers include polyolefin resins such as polypropylene, polyethylene (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymers (including propylene-ethylene copolymers and propylene-butene-1-ethylene copolymers), ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers; polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), and polyethylene naphthalate (PEN). Examples include polyester resins such as polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), and copolymers thereof; polyamide resins such as nylon 6, nylon 12, and nylon 66; acrylic resins containing acrylonitrile as a component; polyvinyl alcohol resins; polyurethane resins; and at least one selected from the group consisting of engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefins, as well as their elastomers. These may be used individually or in combination of two or more.

[0018] Examples of semi-synthetic fibers include acetate fibers. Examples of regenerated fibers include viscose rayon, cupro, solvent-spun cellulose, and polynosic. Examples of natural fibers include cotton, linen, silk, wool, and pulp.

[0019] Among the aforementioned organic fibers, when used in a carbonation-promoting hydraulic composition, it is preferable to use hydrophobic resin fibers containing a hydrophobic resin as the main component, having an official moisture content of 4.0 or less according to JIS L0105:2020 4.1, and to use fibers that have alkali resistance and ultraviolet resistance, from the viewpoint of improving the carbon dioxide fixation properties of the hardened hydraulic composition. Examples of hydrophobic resin fibers of the present invention include polyolefin resins such as polypropylene, polyethylene (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymers mainly composed of propylene (including propylene-ethylene copolymers and propylene-butene-1-ethylene copolymers), ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers; polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), and copolymers thereof; acrylic resins containing acrylonitrile as a component; polyurethane resins; engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefins, and elastomers thereof. Furthermore, the official moisture content of the hydrophobic resin fiber is more preferably less than 3.0, even more preferably less than 2.0, and most preferably less than 1.0. Examples of fibers having alkali resistance and ultraviolet resistance include polyolefin fibers, nylon fibers, vinylon fibers, and aramid fibers. Among the hydrophobic resin fibers, polyolefin resin fibers having moisture and heat resistance, alkali resistance, and ultraviolet resistance are preferred. The polyolefin resin fiber preferably contains 80% by mass or more of polyolefin resin, more preferably 90% by mass or more, and particularly preferably all (100% by mass) of the resin component is polyolefin resin.

[0020] Examples of the polyolefin resins include polypropylene resins, polyethylene resins, and polymethylpentene resins.

[0021] The polypropylene resin may be a propylene homopolymer or a propylene copolymer. Examples of propylene copolymers include copolymers of propylene and other α-olefins. The other α-olefin may be at least one selected from the group consisting of ethylene with 2 carbon atoms and α-olefins with 4 or more carbon atoms. Examples of α-olefins with 4 or more carbon atoms are not particularly limited, but include 1-butene, 1-pentene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1-decene, 1-dodecene, 1-tetradecene, and 1-octadecene. In the propylene copolymer, the propylene content is preferably 85 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more.

[0022] Examples of the polyethylene resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene.

[0023] The polymethylpentene resin may be a homopolymer of 4-methylpentene-1 or a copolymer of 4-methylpentene-1. Examples of copolymers of 4-methylpentene-1 include copolymers of 4-methylpentene-1 and other α-olefins. Examples of other α-olefins include copolymers of one or two α-olefins having 2 to 20 carbon atoms, preferably 8 to 18 carbon atoms, as described above. The copolymer of 4-methylpentene-1 may contain 85 mol% or more, 90 mol% or more, 95 mol% or more, or 95 mol% or more of 4-methylpentene-1.

[0024] The polyolefin resin may be used alone or in combination of two or more. The polyolefin resin fiber preferably contains at least one selected from the group consisting of the polypropylene resin and the polymethylpentene resin from the viewpoints of wet heat resistance, alkali resistance, and curing, and more preferably contains at least one selected from the group consisting of the polypropylene resin and the polymethylpentene resin as a main component.

[0025] The organic fiber may be a single fiber or a composite fiber. The composite fiber may be any of a core-sheath type composite fiber, a side-by-side type composite fiber, a split type composite fiber, and a sea-island type composite fiber. When the organic fiber is a core-sheath type composite fiber, the core-sheath type composite fiber may be a concentric core-sheath type composite fiber or an eccentric core-sheath type composite fiber. When the organic fiber is a core-sheath type composite fiber, the compounding ratio of the core component and the sheath component is not particularly limited, but the core component / sheath component may be 90 / 10 or more and 10 / 90 or less in terms of mass ratio, more preferably 80 / 20 or more and 20 / 80 or less, and most preferably 70 / 30 or more and 30 / 70 or less. When the organic fiber is a core-sheath type composite fiber, it is preferable that the hydrophobicity of the hydrophobic resin constituting the sheath component is higher than the hydrophobicity of the hydrophobic resin constituting the core component.

[0026] As the organic fiber, a single fiber of a polypropylene fiber, a core-sheath type composite fiber in which the core component is made of a polypropylene resin and the sheath component is made of a polymethylpentene resin having higher hydrophobicity than the polypropylene resin, etc., can be preferably used. By using a resin having high hydrophobicity as the sheath component, even when the water repellent surface treatment agent peels off or the water repellency decreases, it is easy to hold air bubbles, and it is presumed that this is due to ensuring a flow path of air containing CO ２ and an increase in the reaction (fixation) amount of CO ２

[0027] The cross-sectional shape of the organic fiber is not particularly limited, and may be a circular cross-section or a non-circular cross-section (non-circular cross-section) other than the circular cross-section. A non-circular cross-section is preferable, a circular hollow cross-section or a non-circular hollow cross-section is more preferable, and a triangular hollow cross-section or a pentagonal hollow cross-section is further preferable.

[0028] The organic fiber is not particularly limited. For example, from the perspective of workability, the fiber diameter of the single fiber is preferably 8 μm or more and 700 μm or less, more preferably 8 μm or more and 100 μm or less, and even more preferably 9 μm or more and 80 μm or less. In this specification, when the fiber cross-section is circular, the fiber diameter means the diameter of the fiber cross-section. When the fiber cross-section is non-circular, the fiber diameter means the diameter of the circumscribed circle of the fiber cross-section (the maximum length across). When there is no circumscribed circle of the fiber cross-section, the fiber diameter means the maximum length across of the minimum enclosing circle.

[0029] The organic fiber is not particularly limited. For example, from the perspective of workability, the fiber length of the single fiber is preferably 0.5 mm or more and 50 mm or less, more preferably 2 mm or more and 30 mm or less, and even more preferably 3 mm or more and 15 mm or less.

[0030] The water repellent treatment agent may be any treatment agent that can impart water repellency to the fiber surface and is not particularly limited. For example, from the perspective of enhancing the degree of water repellency and improving the performance of the organic fiber to hold air bubbles, it preferably contains an emulsion of a fluororesin (also referred to as an emulsion) or an emulsion of a silicone resin, and more preferably contains an emulsion of a fluororesin.

[0031] The emulsion of the fluororesin is not particularly limited, and known ones can be appropriately used. For example, emulsions of polymers of fluoroolefins such as ethylene tetrafluoride and propylene hexafluoride, emulsions of modified fluororesins copolymerized with fluoroolefins and acrylic monomers, and emulsions of acrylate compounds having a perfluoro group in the side chain can be mentioned. Examples of commercially available emulsions of fluorine-based water repellent treatment agents include the M Guard series manufactured by Matsumoto Yushi Seiyaku Co., Ltd., the Asahi Guard E series manufactured by Asahi Glass Co., Ltd., the NK Guard series manufactured by Nihon Kayaku Co., Ltd., and the TG series manufactured by Daikin Industries, Ltd.

[0032] The emulsion of the silicone resin is not particularly limited, and known emulsions of organopolysiloxanes can be used as appropriate. Organopolysiloxanes are resins having a structure in which silicon (Si) and oxygen (O) atoms, to which organic groups are bonded, are alternately linked by chemical bonds, and generally include silicone resins, silsesquioxanes, and silicone oils. Examples of the organopolysiloxanes include dimethylpolysiloxane, diethylpolysiloxane, dipropylpolysiloxane, dibutylpolysiloxane, diisopropylpolysiloxane, dihexylpolysiloxane, dioctylpolysiloxane, ethylmethylpolysiloxane, methylpropylpolysiloxane, butylmethylpolysiloxane, isopropylmethylpolysiloxane, hexylmethylpolysiloxane, methyloctylpolysiloxane, ethylpropylpolysiloxane, butyloctylpolysiloxane, and methylphenylsiloxane. Furthermore, the organopolysiloxane may be a modified polysiloxane having reactive organic groups such as amino groups, carboxyl groups, epoxy groups, and acrylic groups.

[0033] In the first embodiment, the amount of water-repellent treatment agent (preferably a fluororesin emulsion or a silicone resin emulsion) adhering to the fiber surface of the organic fiber is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.03% by mass or more and 2% by mass or less, and even more preferably 0.08% by mass or more and 1.4% by mass or less, in terms of solid content (active ingredient). Even if the amount of water-repellent treatment agent adhering exceeds 3% by mass, the water repellency does not change dramatically, so it is not necessarily required to exceed 3% by mass. If the amount of water-repellent treatment agent adhering is 0.01% by mass or less, the degree of water repellency is low, and CO2 is present near the fiber. ２ This makes it less likely for voids that serve as air passages containing the substance to form. In this specification, the amount of water-repellent treatment agent applied can be measured as described in the examples.

[0034] In the second embodiment, the short fiber bundles of the organic fibers are moistened with a liquid containing the water-repellent treatment agent and water, and the moisture content is 5% by mass or more and 60% by mass or less. When the moisture content of the short fiber bundles of the organic fibers is 5% by mass or more, they mix easily when mixed with cement. Also, when the moisture content of the short fiber bundles of the organic fibers is 60% by mass or more, adjusting the moisture content in the cement slurry becomes complicated. The moisture content of the short fiber bundles of the organic fibers is preferably 5% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

[0035] In the second embodiment, the amount of water-repellent treatment agent (preferably a fluororesin emulsion or a silicone resin emulsion) adhering to the fiber surface of the organic fiber is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.03% by mass or more and 2% by mass or less, and even more preferably 0.08% by mass or more and 1.4% by mass or less, in terms of solid content (active ingredient). Even if the amount of water-repellent treatment agent adhering exceeds 3% by mass, the water repellency does not change dramatically, so it is not necessarily required to exceed 3% by mass. If the amount of water-repellent treatment agent adhering is 0.01% by mass or less, the degree of water repellency is low, and CO2 is present near the fiber. ２ This makes it less likely for voids that serve as air passages containing the substance to form. In this specification, the amount of water-repellent treatment agent applied can be measured as described in the examples.

[0036] In the third embodiment, a portion of the organic fibers is bound together with a water-repellent treatment agent, and the moisture content is preferably less than 5% by mass, more preferably 4% by mass or less, and even more preferably 3% by mass or less. This increases the degree of curing and fixation of the water-repellent treatment agent, particularly the emulsion of a fluororesin, in the organic fibers. In this specification, the moisture content of the organic fibers can be measured as described in the examples.

[0037] In the third embodiment, the amount of water-repellent treatment agent (preferably a fluororesin emulsion or a silicone resin emulsion) adhering to the fiber surface of the organic fiber is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.03% by mass or more and 2% by mass or less, and even more preferably 0.08% by mass or more and 1.4% by mass or less, in terms of solid content (active ingredient). Even if the amount of water-repellent treatment agent adhering is 3% by mass or more, the water repellency does not change dramatically, so it is not necessarily required to be 3% by mass or more. If the amount of water-repellent treatment agent adhering is 0.01% by mass or less, the degree of water repellency is low, and CO2 is released near the fiber. ２ This makes it less likely for voids that serve as air passages containing the substance to form. In this specification, the amount of water-repellent treatment agent applied can be measured as described in the examples.

[0038] (Method for manufacturing additives for carbonation-promoting hydraulic compositions) As described above, additives for carbonation-promoting hydraulic compositions are used in carbonation-promoting hydraulic compositions such as cement compositions that can fix carbon dioxide, and contain organic fibers or short fiber bundles of organic fibers. The method for manufacturing additives for carbonation-promoting hydraulic compositions, more specifically the first, second, and third embodiments described above, is not particularly limited, but it is preferable to include, for example, step A of treating organic fibers with a water-repellent treatment agent. The organic fibers and water-repellent treatment agents described above can be used, respectively.

[0039] When using a fluororesin emulsion or a silicone resin emulsion as the water-repellent treatment agent, it is preferable in step A to treat the organic fibers using a treatment solution containing the water-repellent treatment agent and water, by at least one means selected from the group consisting of immersion, coating, and spraying. In step A, it is preferable to use the organic fibers in the form of a continuous long fiber bundle (tow) in which multiple single fibers are bundled together. Specifically, a hydrophobic resin can be melt-spun, the resulting spun filament (undrawn filament) can be drawn, and the drawn filament (organic fiber in the form of a continuous long fiber bundle in which multiple single fibers are bundled together) can be used in step A. After step A, in step B, the long fiber bundle treated with the treatment solution can be cut to a predetermined fiber length to obtain a short fiber bundle. The cut length is preferably, for example, 0.5 mm or more and 50 mm or less, more preferably 2 mm or more and 30 mm or less, and even more preferably 3 mm or more and 15 mm or less. After step A and before step B, in step C, the moisture content of the long fiber bundle treated with the treatment liquid is adjusted to 5% by mass or more and 60% by mass or less, thereby obtaining the additive for the carbonation-promoting hydraulic composition (short fiber bundle of organic fibers) of the second embodiment after step B. Before step B, as step D, the long fiber bundle of organic fibers may be dried, preferably after step C and before step B. By drying, the additive for the carbonation-promoting hydraulic composition (short fibers of organic fibers) of the first or third embodiment can be obtained.

[0040] When the organic fiber is a polyolefin resin fiber, the additive for the carbonation-promoting hydraulic composition can be manufactured, for example, as follows.

[0041] First, using one or more of the polyolefin resins, melt spinning is performed at the temperature at which the polyolefin resin melts, using a single-type or composite-type nozzle that produces a predetermined shape, and the material is taken up at a draw speed of 100 m / min to 2000 m / min, thereby obtaining spun filaments with a single fiber fineness of 4 decitex to 80 decitex. Hereinafter, "decitex" will be abbreviated as "dtex". The spinning temperature may be, for example, 250°C to 310°C or 270°C to 300°C if the polyolefin resin is a polypropylene resin, and for example, 260°C to 320°C or 280°C to 300°C if the polyolefin resin is a polymethylpentene resin.

[0042] Next, the spun filament is drawn to obtain a drawn filament. This improves the single-fiber strength of the organic fiber. The drawn filament preferably has a single-fiber fineness of 0.5 dtex or more and 30 dtex or less, more preferably 0.8 dtex or more and 20 dtex or less, and even more preferably 1.0 dtex or more and 6 dtex or less. The drawing temperature and drawing ratio are not particularly limited, but for example, it is preferable to draw the filament at a drawing temperature of 80°C or more and 140°C or less and a drawing ratio of 1.1 times or more and 8 times or less. A more preferable drawing temperature is 100°C or more and 150°C or less. A more preferable drawing ratio is 2 times or more and 6 times or less. The stretching method is not particularly limited, and the stretching process can be carried out using known methods such as wet stretching, which involves stretching while heating with a high-temperature liquid such as hot water; dry stretching, which involves stretching while heating in a high-temperature gas or with a high-temperature metal roll; and steam stretching, which involves stretching while heating the fibers with steam at 100°C or higher at atmospheric pressure or under pressure. These stretching methods can also be combined, such as performing wet stretching followed by dry stretching, or performing dry stretching multiple times. Stretching may be carried out in one stage or in a so-called multi-stage stretching process divided into multiple stages. If only wet stretching is performed, the fibers may be dried before use in step A.

[0043] Next, in step A, it is preferable to treat the stretched filament (organic fiber) using a treatment solution containing a water-repellent agent and water by at least one means selected from the group consisting of immersion, coating, and spraying. The treatment solution preferably contains 0.1% to 20% by mass of a fluororesin emulsion or a silicone resin emulsion on a solid content (component) basis, more preferably 0.5% to 10% by mass, and even more preferably 1% to 5% by mass. The temperature of the treatment solution is not particularly limited, but may be, for example, 10°C to 60°C, 20°C to 50°C, 30°C to 50°C, or 35°C to 45°C.

[0044] After step A, in step B, the long fiber bundle treated with the treatment liquid is cut to a predetermined fiber length to obtain a wet short fiber bundle. Before step B, crimp may be applied as needed. Before step B, as step D, the wet short fiber bundle is dried (cured) using a heat transfer medium such as hot air, infrared (IR), and steam to obtain the additive for the carbonation-promoting hydraulic composition (short organic fibers) of the first or third embodiment. The drying (curing) temperature is not particularly limited, but for example, it may be 80°C to 140°C, preferably 90°C to 130°C, and more preferably 100°C to 120°C. The drying (curing) time may be 1 minute to 60 minutes, preferably 2 minutes to 30 minutes, and more preferably 3 minutes to 20 minutes.

[0045] After step A and before step B, in step C, the moisture content of the long fiber bundle treated with the treatment liquid is adjusted to 5% by mass or more and 60% by mass or less, preferably 15% by mass or more and 55% by mass or less, more preferably 30% by mass or more and 50% by mass or less, thereby obtaining the additive for the carbonation-promoting hydraulic composition of the second embodiment (short fiber bundle of organic fibers) after step B. The moisture content can be adjusted by squeezing the long fiber bundle treated with the water-repellent treatment agent using a mangle roll or the like. Before step B, the short fiber bundle of organic fibers may be dried (cured), preferably after step C and before step B. By drying (curing), the additive for the carbonation-promoting hydraulic composition of the first or third embodiment (short organic fibers) can be obtained. The drying (curing) temperature is not particularly limited, but for example, it may be 80°C or more and 140°C or less, preferably 90°C or more and 130°C or less, and more preferably 100°C or more and 120°C or less. The drying (curing) time may be between 1 minute and 60 minutes, preferably between 2 minutes and 30 minutes, and more preferably between 3 minutes and 20 minutes.

[0046] (Hydraulic composition hardened body) A hydraulic composition hardened body such as a cement hardened body contains the above-mentioned additive for the carbonation-promoting hydraulic composition (hereinafter also referred to simply as the additive).

[0047] In the hardened hydraulic composition, the content of the additive is not particularly limited, but is preferably 0.01 Vol% to 5 Vol%, more preferably 0.02 Vol% to 2 Vol%, and even more preferably 0.05 Vol% to 0.3 Vol%. When the content of the additive in the hardened hydraulic composition is 0.01 Vol% or more, the carbon dioxide fixing ability of the hardened hydraulic composition is improved. When the content of the additive in the hardened hydraulic composition is 5 Vol% or less, it is easier to suppress the generation of fiber balls when preparing hydraulic compositions such as cement compositions (slurries), and it is possible to suppress the decrease in mechanical strength such as compressive strength of the hardened hydraulic composition.

[0048] The hardened hydraulic composition can be obtained by hardening a hydraulic composition, such as a cement composition containing the additive, cement, water, and aggregate, and then curing it by carbonation.

[0049] The cement is not particularly limited, and various types of cement can be used, such as ordinary Portland cement, rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, moderate-heat Portland cement, low-heat Portland cement, fly ash cement, and blast furnace cement.

[0050] The aggregate is not particularly limited and examples include silica sand, river sand, sea sand, beach sand, and crushed stone. The particle size of the aggregate can be selected from among the aggregates according to the intended use of the concrete composition and used as appropriate as fine aggregate or coarse aggregate. Fine aggregate or coarse aggregate may be used alone or in combination of two or more types.

[0051] The hydraulic composition, such as the cement composition, may further contain admixtures. There are no particular restrictions on the admixtures, and various cement admixtures can be used as appropriate. For example, blast furnace slag powder, fly ash, and silica fume can be commonly used. The admixtures may be used individually or in combination of two or more.

[0052] As the admixture, from the viewpoint of improving the carbon fixation properties of the hydraulic composition hardened body, CO ２ Fine powder or adsorbent capable of adsorbing carbon dioxide, such as calcium oxide (CaO) fine powder, may be used. As a fine powder or adsorbent capable of adsorbing carbon dioxide, slag containing γ-2CaO・SiO2 (also referred to as γ-C2S) is preferred. In the hydraulic composition such as the cement composition, the amount of γ-C2S is preferably 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of cement. Excellent carbon dioxide adsorption capacity is exhibited within this range, and the mechanical properties are also excellent.

[0053] The hydraulic composition, such as the cement composition, may further contain admixtures. Various admixtures, such as AE agents, AE water-reducing agents, high-performance AE water-reducing agents, fluidizers, hardening accelerators, rust inhibitors, setting retarders, quick-setting agents, and shrinkage-reducing agents, can be appropriately selected and used depending on the purpose and application. Examples of high-performance AE water-reducing agents (also called defoaming agents) include naphthalene sulfonate-based, polycarboxylic acid-based, melamine sulfonic acid-based, and aminosulfonic acid-based agents, with polycarboxylic acid-based water-reducing agents being preferred. The admixtures may be used individually or in combination of two or more.

[0054] A hardened hydraulic composition, such as a cement composition, can be cured by hardening the hydraulic composition and then undergoing carbonation curing. Specifically, a hydraulic composition, such as a cement composition, can be filled into a mold of a predetermined shape, and after casting the hydraulic composition, sufficient moisture can be supplied to prevent the surface of the hydraulic composition from drying out. After wet curing, the mold can be removed and then subjected to carbonation curing. In wet curing, known methods for supplying moisture include flooding, watering, dampening, wet sand curing, and spray curing, allowing for wet curing while supplying water to the surface of the hydraulic composition.

[0055] The carbonation curing process involves curing the hardened hydraulic composition obtained during the curing process in an environment with a carbon dioxide volume concentration of 5% or more, thereby absorbing and fixing carbon dioxide into the hardened hydraulic composition. While there are no particular restrictions on the carbon dioxide volume concentration, it can be between 5% and 100%.

[0056] The aforementioned cement hardened body or other hydraulic composition hardened body has a compressive strength of 15 N / mm² at a young age of 7 days, for example. 2 It is preferable that the N / mm² is greater than or equal to 20 N / mm². 2 The above is preferable, and more preferably 30 N / mm 2 That's all.

[0057] The present invention will be described in detail below with reference to examples. The present invention is not limited to the following examples.

[0058] The measurement methods used in the examples and comparative examples will be explained.

[0059] (Fiber diameter) The cross-sections of 20 arbitrarily selected fibers were observed using a scanning electron microscope (Hitachi High-Technologies Corporation, model number "SU3500"), and the diameter of each fiber cross-section was measured using 2D image measurement software (SCALA Corporation, MicroMeasure). The arithmetic mean of these measurements was defined as the fiber diameter.

[0060] (Contact angle with water) Fiber samples were laid flat, and deionized water was sprayed using a spray bottle with a droplet size suitable for the fiber sample. A Keyence microscope (VHX-6000) was used to photograph the water droplets attached to the fiber sample, and the contact angle of the water droplets of 20 arbitrarily selected fibers was measured. The average value of these measurements was then calculated and defined as the contact angle with water.

[0061] (Sedimentation velocity in water) (1) 0.3 g of fiber was weighed and used as the sample before washing. (2) 0.3 g of fiber was weighed and the weighed fiber and 1 L of tap water were placed in a mixer (Aikousha: Tabletop mixer Kenmix Aiko Premier KMM770) and stirred at approximately 180 rpm for 1 minute. After stirring, the fiber was squeezed and dried at 80°C until a constant weight was reached, and used as the sample after washing. The samples before and after washing were gently dropped into water at a water temperature of approximately 25°C from a height of 12 mm above the surface to a depth of 50 mm. The time from when the rolled sample was dropped until the entire sample sank below the water surface was measured, and these were recorded as the sedimentation velocity of the fiber before washing and the sedimentation velocity after washing, respectively.

[0062] (Amount of fiber treatment agent attached) Fibers to be measured for the amount of fiber treatment agent attached were dried for 180 minutes using a constant temperature dryer set to 60°C. 4 g was weighed from the dried fibers and used as a sample. The sample was placed in a stainless steel column for oil extraction, and 10 mL of organic solvent was added. After 2 minutes, the extract was squeezed out of the extraction vessel by pistoning an air cylinder for 10 minutes, and the extract flowing out of the outlet was collected in a stainless steel dish. The mass of the stainless steel dish before receiving the extract was W0. Subsequently, the stainless steel dish containing the extract was heated with a heater at 150°C to evaporate the methanol component, and then cooled at room temperature (23°C) for 2 minutes. After that, the mass of the stainless steel dish after evaporation of the methanol component (W1) was measured, and the increased mass (W1 - W0) was divided by the fiber mass to calculate the value, and the average of the two measurements was taken as the amount of fiber treatment agent attached to the fiber mass (mass %). For oil extraction, a stainless steel column was used. The column had a total length of 133.3 mm, an outer diameter of 21.5 mm, an inner diameter of 15.9 mm, a conical tip (outlet) length of 13.0 mm, and an outlet hole diameter of 1.6 mm. Methanol and hexane were used as organic solvents, and the one with the higher deposition rate was adopted.

[0063] (Moisture content) The moisture content was measured in accordance with JIS L 1015 8.1.2. Specifically, approximately 5 g of short fiber bundles were taken as samples. The mass of the sample and the mass under standard conditions were measured, and the moisture content (%) was calculated using the following formula. The average of the two measurements was rounded to one decimal place according to JIS-Z-8401. f =(m-m') / m'×100 R f : Moisture content (%) m: Mass of the sample at the time of sampling (g) m': Mass of the sample under standard conditions (g)

[0064] (Compressive strength of hardened cement) The compressive strength was measured in accordance with JIS A 1108.

[0065] (Carbon fixation amount in cement hardened material) The prepared mortar test specimens were sliced ​​every 20 mm from the exposed surface and finely ground to obtain samples. Next, the samples were burned in an oxygen atmosphere using a carbon-sulfur analyzer (TC) to determine the amount of carbon in the samples. After eliminating the amount of carbon originating from the material by subtracting the measured amount of carbon in the sample of the mortar test specimen that was cured in air from the measured amount of carbon in the sample of the mortar test specimen that was cured in carbon dioxide, the amount of carbon fixation amount in the cement hardened material was determined.

[0066] (Example 1) A polypropylene resin (polypropylene homopolymer, manufactured by Nippon Polypropylene Co., Ltd., product name "SA01A", melting point 160°C) was melt-extruded using a spinning nozzle with a circular nozzle hole shape at a spinning temperature of 290°C, and taken up at a take-up speed of 222 m / min to produce a 15 dtex spun filament (undrawn yarn). The obtained spun filament was dry-drawn 2.5 times at 130°C (single-stage drawing). The obtained drawn yarn was immersed in a treatment solution containing water-repellent treatment agent 1 (active ingredient: 90% by mass of fluororesin and 10% by mass of emulsifier, with an active ingredient concentration of 20% by mass) and water (active ingredient concentration of water-repellent treatment agent 1 is 5% by mass), then squeezed with a mangle roll to adjust the moisture content to 40%, dried at 120°C for 10 minutes, and then cut to a fiber length of 6 mm to obtain short polypropylene fibers (circular cross-section) with a single fiber fineness of 5.4 dtex. Some of the obtained short fibers were clustered together.

[0067] (Example 2) Polypropylene fibers (short fibers) were obtained in the same manner as in Example 1, except that a treatment solution containing water-repellent treatment agent 2 (active ingredients: 60% by mass of alkyl phosphate potassium salt, 10% by mass of polydimethylsiloxane) and water was used as the fiber treatment agent (the concentration of the active ingredients of water-repellent treatment agent 2 was 5% by mass). Some of the short fibers obtained were clustered together.

[0068] (Example 3) A polypropylene resin (polypropylene homopolymer, manufactured by Nippon Polypropylene Co., Ltd., product name "SA01A", melting point 160°C) was used as the core component, and a polymethylpentene resin (4-methylpentene-1 homopolymer, manufactured by Mitsui Chemicals, Inc., product name "DX820", melting point 233°C) was used as the sheath component. Using a concentric core-sheath composite nozzle, the core component was spun at a spinning temperature of 290°C and the sheath component at a spinning temperature of 270°C, so that the composite ratio of the core component and the sheath component was 60:40 by mass ratio. The fibers were taken up at a take-up speed of 222 m / min to produce a 15 dtex spun filament (undrawn yarn). The obtained spun filament was dry-drawn 2.5 times at 130°C (single-stage drawing). The obtained drawn yarn was immersed in a treatment solution containing water-repellent treatment agent 1 (active ingredient: 90% by mass of fluororesin and 10% by mass of emulsifier, with an active ingredient concentration of 20% by mass) and water at room temperature (active ingredient concentration of water-repellent treatment agent 1: 5% by mass). After that, it was squeezed with a mangle roll to adjust the moisture content to 40%, and dried at 120°C for 10 minutes. The obtained spun filaments were cut to a fiber length of 6 mm to obtain short polypropylene fibers (core-sheath composite fibers, circular cross-section) with a single fiber fineness of 5.4 dtex. Some of the obtained short fibers were clustered together.

[0069] (Example 4) Short polypropylene fibers (core-sheath composite fibers, circular cross-section) were obtained in the same manner as in Example 3, except that a treatment solution containing water (active ingredients: 60% by mass of alkyl phosphate potassium salt, 10% by mass of polydimethylsiloxane, with an active ingredient concentration of 30% by mass) and water was used as the fiber treatment agent. Some of the obtained short fibers were clustered together.

[0070] (Comparative Example 1) A hydrophilic treatment agent (active ingredient: 100% by mass of alkyl phosphate potassium salt, concentration of the active ingredient: 60% by mass) and a treatment solution containing water (concentration of the active ingredient of the hydrophilic treatment agent: 5% by mass) were used as the fiber treatment agent, and polypropylene fibers (short fibers) were obtained in the same manner as in Example 1, except that the drying step at 120°C was omitted.

[0071] (Comparative Example 2) A hydrophilic treatment agent (active ingredient: 100% by mass of alkyl phosphate potassium salt, concentration of the active ingredient: 60% by mass) and a treatment solution containing water (concentration of the active ingredient of the hydrophilic treatment agent: 5% by mass) were used as the fiber treatment agent, and short polypropylene fibers (core-sheath composite fibers, circular cross-section) were obtained in the same manner as in Example 3, except that the drying step at 120°C was omitted.

[0072] The moisture content of the polypropylene fibers (short fibers) obtained in Examples 1-4 and Comparative Examples 1-2 was measured as described above, and the results are shown in Table 1 below. The fiber diameter and water contact angle of the short fibers obtained in Examples 1-4 and Comparative Examples 1-2 were also measured as described above, and the results are shown in Table 1 below. Furthermore, the sedimentation velocity in water and the amount of fiber treatment agent adhering to the short fibers obtained in Examples 1-4 and Comparative Examples 1-2 were measured before and after washing, and the results are shown in Table 1 below. In Examples 1-4, some of the polypropylene fibers (short fibers) were bundled by the fiber treatment agent.

[0073]

[0074] (Example 5) The materials shown in Table 2 below, and the short fibers of the polypropylene fiber from Example 3 (density: 0.866 g / cm³) 3 (Hereafter also simply referred to as water-repellent PT1.) was stirred and mixed according to the proportions shown in Table 3 below to obtain a cement composition (mortar composition). In Table 3 below, W represents water. The obtained cement composition was poured into a rectangular formwork (4 × 4 × 16 cm) and a cylindrical formwork (5 cm in diameter, 10 cm in height), respectively, and cured in the formwork at room temperature for one day. After that, it was left to stand for two days in an atmosphere of 20°C and 60% RH, and then CO ２ The specimens were cured in a 20% concentration, 20°C, and 60% RH atmosphere for 5 days to obtain prismatic and cylindrical specimens. CO2 levels during the curing of the prismatic specimens were measured. ２ The exposed surface was the end face, and the other sides were sealed with aluminum tape to promote carbonation from both ends. The cylindrical test specimens were subjected to carbonation curing with the entire surface open.

[0075] (Reference Example 1) After curing the formwork for one day, the specimens were cured in air for seven days at 20°C and 60% RH without carbonation curing, except that they were prepared in the same manner as in Example 5, to obtain prismatic and cylindrical specimens.

[0076] (Example 6) Instead of the short polypropylene fibers of Example 3, the short polypropylene fibers of Example 4 (density: 0.866 g / cm³) are used. 3 Prismal and cylindrical test specimens were obtained in the same manner as in Example 5, except that a water-repellent PT2 (hereinafter also simply referred to as PT2) was used.

[0077] (Reference Example 2) After curing the formwork for one day, the specimens were cured in air for seven days at 20°C and 60% RH without carbonation curing, except that they were prepared in the same manner as in Example 6, to obtain prismatic and cylindrical specimens.

[0078] (Comparative Example 3) Instead of the short polypropylene fibers of Example 3, the short core-sheath composite fibers of Comparative Example 2 (density: 0.866 g / cm³) are used. 3 Prismal and cylindrical specimens were obtained in the same manner as in Example 5, except that hydrophilic PT was used.

[0079] (Reference Example 3) After curing the formwork for one day, the specimens were cured in air for seven days at 20°C and 60% RH without carbonation curing, except that they were prepared in the same manner as in Comparative Example 3, to obtain prismatic and cylindrical specimens.

[0080] (Comparative Example 4) Prismatic and cylindrical specimens were obtained in the same manner as in Example 5, except that no fibers were used.

[0081] (Reference Example 4) After curing the formwork for one day, the specimens were cured in air for seven days at 20°C and 60% RH without carbonation curing, except that they were prepared in the same manner as in Comparative Example 4, to obtain prismatic and cylindrical specimens.

[0082]

[0083]

[0084] The compressive strength of the cylindrical specimens obtained in Examples 5-6 and Comparative Examples 3-4 was measured as described above. Furthermore, the amount of carbon fixed in the mortar specimens obtained by carbonation curing in Examples 5-6 and Comparative Examples 3-4 was measured as described above. In measuring the amount of carbon fixed, the mortar specimens obtained in Reference Examples 1-4 were used as air-cured mortar specimens corresponding to the mortar specimens obtained by carbonation curing in Examples 5-6 and Comparative Examples 3-4. The results are shown in Table 4 below.

[0085]

[0086] From Table 4 above, it was found that the compressive strength of the mortar test specimens of Examples 5 and 6, obtained by carbonation curing of a mortar composition using short fiber bundles of polyolefin resin fibers treated with a water-repellent agent, was almost equivalent to the compressive strength of the mortar test specimen of Comparative Example 4, obtained by carbonation curing of a mortar composition with the same composition except that no fibers were used.

[0087] Furthermore, as can be seen from Table 4 above, the amount of carbon fixed in the surface layer of the mortar test specimens of Examples 5-6, obtained by carbonation curing of mortar compositions using short polyolefin resin fibers treated with a water-repellent treatment agent, and the mortar test specimen of Comparative Example 3, obtained by carbonation curing of a mortar composition using short fiber bundles of polyolefin resin fibers surface-treated with a hydrophilic treatment agent, was greater than the amount of carbon fixed in the surface layer of the mortar test specimen of Comparative Example 4, obtained by carbonation curing of a mortar composition with the same composition except that no fibers were used. In addition, the amount of carbon fixed in the deeper parts of the test specimens of Examples 5-6, obtained by carbonation curing of mortar compositions using short fiber bundles of polyolefin resin fibers surface-treated with a water-repellent treatment agent, was also increased compared to Comparative Examples 3 and 4. This is because the water-repellent surface of the organic fibers (polyolefin resin fibers) surface-treated with a water-repellent treatment agent suppresses the adhesion of water to the fiber interface of the organic fibers, resulting in fine voids and CO ２ This is presumed to be due to the movement route and its function.

[0088] (Example 7) A mixture containing 10% by mass of an amine compound composed of tertiary amino groups in polypropylene resin (manufactured by Nippon Polypropylene Co., Ltd., product name "SA03") was used. Using a spinning nozzle with a pentagonal hollow nozzle hole shape, melt extrusion was performed at a spinning temperature of 220°C, and the material was taken up at a take-up speed of 200 m / min to produce a spun filament (undrawn yarn) with a fineness of 20 dtex. The obtained spun filament was dry-drawn three times at 130°C (single-stage drawing). The obtained stretched filament was immersed in a treatment solution containing a water-repellent treatment agent 1 (active ingredient: 90% by mass of fluororesin and 10% by mass of emulsifier, with an active ingredient concentration of 20% by mass) and water (active ingredient concentration of the water-repellent treatment agent 1 was 5% by mass), then squeezed with a mangle roll to adjust the moisture content to about 40%, dried at 105°C for 15 minutes, and then cut to a fiber length of 10 mm to obtain short polypropylene fibers (pentagonal hollow cross-section) with a single fiber fineness of 7 dtex (fiber diameter 50.8 μm). Some of the obtained short fibers were clustered together.

[0089] (Comparative Example 5) A mixture containing 10% by mass of an amine compound composed of tertiary amino groups in polypropylene resin (manufactured by Nippon Polypropylene Co., Ltd., trade name "SA03") was used. Using a spinning nozzle with a pentagonal hollow nozzle hole shape, melt extrusion was performed at a spinning temperature of 220°C, and the material was taken up at a take-up speed of 200 m / min to produce a spun filament (undrawn yarn) with a fineness of 20 dtex. The obtained spun filament was dry-drawn three times at 130°C (single-stage drawing). The total discharge rate for the obtained drawn filament was 0.3 kW / m ２ The fibers were treated with corona discharge under conditions of / min to make them hydrophilic, and then immersed in a treatment solution containing a hydrophilic treatment agent (active ingredient: 100% by mass of alkyl phosphate potassium salt, with an active ingredient concentration of 60% by mass) and water (with an active ingredient concentration of 5% by mass). After that, they were squeezed with a mangle roll to adjust the moisture content to about 40%, dried at 105°C for 15 minutes, cut to a fiber length of 10 mm, and short fiber bundles and short fibers 8 of pentagonal hollow fibers with a fineness of 7 dtex (fiber diameter 50.8 μm) were obtained.

[0090] <Preparation of Hardened Cement> The materials shown in Table 5 below, along with the fibers 7 and 8 obtained above, were stirred and mixed according to the proportions shown in Table 6 below to obtain a cement composition (mortar composition). In Table 6 below, W represents water. The obtained cement composition was poured into a rectangular prism-shaped mold (4 × 4 × 16 cm) and a cylindrical mold (5 cm in diameter, 10 cm in height), respectively, and cured in the molds at room temperature for one day. After that, it was cured under the following conditions to obtain rectangular prism and cylindrical test specimens. Curing in air followed by carbonation: Left to stand for two days in an atmosphere of 20°C and 60% RH (curing in air), and then CO ２ The specimens were left to stand for 7 days in an atmosphere of 80% concentration, 20°C, and 60% RH (carbonation curing). CO2 during carbonation curing of the prismatic specimens. ２ Only one end face of the specimen was exposed, and the other face was sealed with aluminum tape before curing. The cylindrical specimens were cured with the entire surface open. A cement hardened body without added fibers was prepared as Comparative Example 6. (Carbonation Depth) To measure the carbonation depth after each curing period, a 4 × 4 × 16 cm rectangular prism specimen was used. At each 10-day test age, the specimen was cut to a thickness of approximately 5 cm, sprayed with phenolphthalein solution, and the depth from the surface to the colored area was measured with calipers. (Carbonation Area Ratio) Based on the measured carbonation depth, the carbonation area ratio of each specimen was calculated using the following formula: ・Carbonation Area Ratio = {40 2 -(40-a) 2} / 40 2 ×100 a = carbonation depth (mm)

[0091] As shown in Table 7, the TC value increased at all levels of fiber addition compared to Comparative Example 6, which did not contain added fibers. Furthermore, the TC value increased more in Example 7, which contained short fibers 7 surface-treated with a hydrophilic oil, compared to Comparative Example 5, which contained short fibers 8 surface-treated with a hydrophilic oil. This suggests that when the purpose is carbon fixation in cement, adding short fibers with a water-repellent surface repels moisture present at the interface between the fiber surface and the matrix, creating voids and thus CO ２ It is presumed that an infiltration pathway has been secured.

[0092] The present invention is not particularly limited, but includes, for example, the following embodiments: [1] An additive for use in a carbonation-promoting hydraulic composition, characterized in that the additive comprises organic fibers and a water-repellent treatment agent attached to the surface of the organic fibers. [2] An additive for use in a carbonation-promoting hydraulic composition, characterized in that the additive comprises a short fiber bundle of organic fibers, and a liquid containing a water-repellent treatment agent and water, wherein the short fiber bundle is wet with the liquid containing the water-repellent treatment agent and water, and the moisture content is 5% by mass or more and 60% by mass or less. [3] An additive for use in a carbonation-promoting hydraulic composition, characterized in that the additive comprises organic fibers and a water-repellent treatment agent attached to the surface of the organic fibers, wherein a portion of the organic fibers is bound together by the water-repellent treatment agent, and the moisture content is less than 5% by mass. [4] The water-repellent treatment agent comprises an emulsion of a fluororesin or an emulsion of a silicone resin, as an additive for a carbonation-promoting hydraulic composition according to any one of [1] to [3]. [5] The organic fiber has a contact angle with water of 90° or more, as an additive for a carbonation-promoting hydraulic composition according to any one of [1] to [4]. [6] The organic fiber is a hydrophobic resin fiber, as an additive for a carbonation-promoting hydraulic composition according to any one of [1] to [5]. [7] The hydrophobic resin fiber is a polyolefin resin fiber, as an additive for a carbonation-promoting hydraulic composition according to [6]. [8] The polyolefin resin fiber comprises at least one resin selected from the group consisting of polypropylene resins and polymethylpentene resins, as an additive for a carbonation-promoting hydraulic composition according to [7]. [9] The organic fiber has a single fiber diameter of 8 μm or more and 700 μm or less, as an additive for a carbonation-promoting hydraulic composition according to any one of [1] to [8].

[10] The additive for a carbonation-promoting hydraulic composition according to any one of [1] to [9], wherein the organic fiber has a single fiber length of 0.5 mm or more and 50 mm or less.

[11] The additive for a carbonation-promoting hydraulic composition according to any one of [1] to

[10] , wherein the amount of water-repellent treatment agent attached to the organic fiber is 0.01% by mass or more and 3% by mass or less in terms of solid content (active ingredient).

[12] A water-hardening composition cured by carbonation, comprising the additive for carbonation-promoting water-hardening composition described in any one of [1] to

[11] .

[13] The water-hardening composition cured by carbonation, comprising the additive for carbonation-promoting water-hardening composition described in

[12] in an amount of 0.01 Vol% to 5 Vol% with respect to 100 Vol% of the water-hardening composition cured.

[14] A method for producing the additive for carbonation-promoting water-hardening composition described in any one of [1] to

[11] , comprising step A of treating organic fibers with a water-repellent treatment agent.

[15] The method for producing the additive for carbonation-promoting water-hardening composition described in

[14] , wherein the water-repellent treatment agent comprises a fluororesin emulsion or a silicone resin emulsion, and in step A, the organic fibers are treated using a treatment liquid containing the water-repellent treatment agent and water by at least one means selected from the group consisting of immersion, coating, and spraying.

[16] A method for producing an additive for a carbonation-promoting hydraulic composition according to

[14] or

[15] , wherein in step A, the organic fibers are used in the form of a continuous long fiber bundle (tow) in which multiple single fibers are bundled together.

[17] A method for producing an additive for a carbonation-promoting hydraulic composition according to

[16] , further comprising step B, after step A, of cutting the long fiber bundle treated with the treatment liquid to a predetermined fiber length.

[18] A method for producing an additive for a carbonation-promoting hydraulic composition according to

[17] , further comprising step C, after step A and before step B, of adjusting the moisture content of the long fiber bundle treated with the treatment liquid to 5% by mass or more and 60% by mass or less.

[19] A method for producing an additive for a carbonation-promoting hydraulic composition according to any one of

[16] to

[18] , further comprising step D, after step A and before step B, of drying the long fiber bundle treated with the treatment liquid.

[0093] The additive for the carbonation-promoting hydraulic composition of the present invention can be suitably used in hydraulic composition hardened bodies such as cement hardened bodies that can fix various types of carbon dioxide.

Claims

1. An additive for use in a carbonated hydraulic composition, characterized in that the additive is an organic fiber and a water-repellent treatment agent is attached to the surface of the organic fiber.

2. The additive for a carbonation-promoting hydraulic composition according to claim 1, wherein the short fiber bundle is a bundle of organic fibers, further comprising a liquid containing water, the short fiber bundle is wetted with the liquid containing the water-repellent treatment agent and water, and the moisture content is 5% by mass or more and 60% by mass or less.

3. The additive for a carbonation-promoting hydraulic composition according to claim 1, wherein a portion of the organic fibers are bundled by the water-repellent treatment agent and the moisture content is less than 5% by mass.

4. The additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 3, wherein the water-repellent treatment agent comprises a fluororesin emulsion or a silicone resin emulsion.

5. The additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 4, wherein the organic fiber has a contact angle with water of 90° or more.

6. The additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 5, wherein the organic fiber is a hydrophobic resin fiber.

7. The additive for a carbonated hydraulic composition according to claim 6, wherein the hydrophobic resin fiber is a polyolefin resin fiber.

8. The additive for a carbonation-promoting hydraulic composition according to claim 7, wherein the polyolefin resin fiber comprises at least one resin selected from the group consisting of polypropylene resins and polymethylpentene resins.

9. The additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 8, wherein the organic fiber has a single fiber diameter of 9 μm or more and 700 μm or less.

10. The additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 9, wherein the organic fiber has a single fiber length of 0.5 mm or more and 50 mm or less.

11. The additive for a carbonated hydraulic composition according to any one of claims 1 to 10, wherein the amount of the water-repellent treatment agent adhering to the organic fiber is 0.01% by mass or more and 3% by mass or less in terms of solid content (active ingredient).

12. A hardened hydraulic composition comprising the additive for a carbonated hydraulic composition according to any one of claims 1 to 11, and which has been carbonated and cured.

13. The hydraulic composition cured body according to claim 12, wherein the additive for the carbonation-promoting hydraulic composition comprises 0.01 Vol% to 5 Vol% of the hydraulic composition cured body with respect to 100 Vol%.

14. A method for producing an additive for a carbonation-promoting hydraulic composition according to any one of claims 1 to 11, comprising step A of treating organic fibers with a water-repellent treatment agent.

15. The method for producing an additive for a carbonation-promoting hydraulic composition according to claim 14, wherein the water-repellent treatment agent comprises a fluororesin emulsion or a silicone resin emulsion, and in step A, the organic fibers are treated using a treatment solution containing the water-repellent treatment agent and water by at least one means selected from the group consisting of immersion, coating, and spraying.

16. A method for producing an additive for a carbonation-promoting hydraulic composition according to claim 14 or 15, wherein in step A, the organic fibers are used in the form of a continuous long fiber bundle (tow) in which multiple single fibers are bundled together.

17. A method for producing an additive for a carbonation-promoting hydraulic composition according to claim 16, comprising step B, after step A, of cutting the long fiber bundle treated with the treatment liquid to a predetermined fiber length.

18. A method for producing an additive for a carbonation-promoting hydraulic composition according to claim 17, comprising step C, after step A and before step B, of adjusting the moisture content of the long fiber bundle treated with the treatment liquid to 5% by mass or more and 60% by mass or less.

19. A method for producing an additive for a carbonation-promoting hydraulic composition according to claim 17, comprising step D of drying the long fiber bundle treated with the treatment liquid after step A and before step B.

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