Fiber-reinforced cured body

Abstract

To provide a cured body reinforced by fibers and having a high bending strength and a high dimensional stability.SOLUTION: A cured body of a curable composition comprises: (A) an aluminosilicate source; (B) an alkali activator; and (C) alkali-resistant fibers, wherein the aluminosilicate source (A) includes blast furnace slag, a content of the blast furnace slag is 40 mass% or more with respect to the total solid content of the aluminosilicate source (A), a content of the alkali activator (B) is 10 mass% or less with respect to the total solid content of the curable composition, and a water content of the cured body is 10.0 mass% or less with respect to the total mass of the cured body.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced cured body. [Background technology]

[0002] Conventional cement-based materials are widely used in a wide range of fields, particularly civil engineering and construction, due to their versatile manufacturing capabilities. However, cement production requires a significant amount of energy, and the resulting large amount of carbon dioxide emissions is a problem. Therefore, a technology called geopolymer has been investigated in recent years. Geopolymers are inorganic polymers produced by reacting aluminosilicates with alkali metal silicates. Compared to cement-based materials, they have superior durability and acid resistance, and emit significantly less carbon dioxide from the production of raw materials to the final product. Therefore, they have attracted attention as an environmentally friendly material.

[0003] For example, Patent Document 1 describes a hardenable composition in which specific slag particles are added to a hardenable composition containing aluminum silicate, alkali metal silicate, reinforcing fibers, and water in order to improve the toughness of the hardened body without impairing the fluidity of the hardenable composition. Patent Document 2 describes a high-strength composite material obtained by kneading and molding a composition consisting of granulated blast furnace slag, an alkali stimulant, a water-soluble polymer, an ultrafine powder substance, organic short fibers, and water, and then wet curing the composition, and describes that this composite material has excellent resistance to flames. Patent Document 3 describes a geopolymer composition comprising an active filler containing at least one of fly ash, blast furnace slag, sewage incineration sludge, and kaolin, silica or a silica compound, and an alkaline solution, wherein the molar ratio of the amount of silica to the amount of alkali contained in the solution is 0.50 or less. It also describes that this geopolymer composition has improved durability.

[0004] While geopolymers have the aforementioned environmentally friendly advantage, they also have extremely high brittleness. Therefore, as described in Patent Documents 1 and 2, fiber reinforcement has been proposed as an improvement. However, geopolymer curable compositions have very high viscosity and a short pot life, making it difficult to uniformly mix the fibers, thereby making it difficult to fully utilize the reinforcing effect of the fibers. Furthermore, if the fibers are not uniformly mixed, fiber clumps may form, resulting in poor dimensional stability. Furthermore, typical geopolymers use large amounts of alkaline activators to react with aluminosilicates, resulting in poor dimensional stability of the resulting cured bodies. Even with the amount of alkaline activator described in Patent Document 3, immersion of the resulting cured body in water can lead to the dissolution of alkaline components, resulting in poor dimensional stability. These factors have made it difficult to obtain a cured body that combines high bending strength and high dimensional stability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-184221 [Patent Document 2] Japanese Patent Application Publication No. 5-097495 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-157731 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, an object of the present invention is to provide a fiber-reinforced cured product having high bending strength and high dimensional stability. [Means for solving the problem]

[0007] The present inventors have conducted extensive research into cured products in order to solve the above problems, and as a result have completed the present invention. That is, the present invention includes the following preferred embodiments. [1] A cured product of a curable composition comprising (A) an aluminosilicate source, (B) an alkali activator, and (C) an alkali-resistant fiber, the aluminosilicate source (A) contains blast furnace slag, and the content of the blast furnace slag is 40 mass% or more based on the total solid content of the aluminosilicate source (A); the content of the alkali activator (B) is 10 mass% or less based on the total solid content of the curable composition; A hardened body having a moisture content of 10.0 mass% or less based on the total mass of the hardened body. [2] The cured product according to the above [1], wherein the content of the aluminosilicate source (A) is 20 mass % or more and 75 mass % or less based on the total solid content of the curable composition. [3] The cured product according to [1] or [2], wherein the alkali-resistant fiber (C) is at least one selected from the group consisting of polyvinyl alcohol-based fiber, polyethylene fiber, polypropylene fiber, acrylic fiber, aramid fiber, and nylon fiber. [4] The cured product according to any one of [1] to [3] above, wherein the content of the alkali-resistant fiber (C) is 0.05 mass % or more and 5 mass % or less based on the total solid content of the cured product. [5] The cured product according to any one of the above [1] to [4], wherein the alkali-resistant fiber (C) has a fiber aggregation degree of 10% or less. [6] The hardened body according to any one of [1] to [5], wherein the coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces each weighing 10 g, cut out from the whole or part of the hardened body, is 30% or less. [7] The hardened body according to any one of [1] to [6], further comprising an aggregate (E), the content of which is 15% by mass or more and 75% by mass or less based on the total solid content of the hardened body. [8] The hardened body according to any one of the above [1] to [7], wherein the aluminosilicate source (A) further contains at least one selected from the group consisting of fly ash, metakaolin, and red mud. [9] The hardened body according to any one of [1] to [8], further comprising a slag stimulant (D), the content of which is 0.01 mass% or more and 3 mass% or less based on the total solid content of the hardened body.

[10] The hardened body according to any one of [1] to [9], further comprising a calcium sulfate derivative, the content of which is 0.01 mass % or more and 20 mass % or less based on the total solid content of the hardened body. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a fiber-reinforced cured product having high bending strength and high dimensional stability. DETAILED DESCRIPTION OF THE INVENTION

[0009] The cured product of the present invention is a cured product of a curable composition comprising (A) an aluminosilicate source, (B) an alkali activator, and (C) an alkali-resistant fiber. The aluminosilicate source (A) contains blast furnace slag, and the blast furnace slag content is 40 mass% or more based on the total solid content of the aluminosilicate source (A). The alkali activator (B) content is 10 mass% or less based on the total solid content of the curable composition. The moisture content of the cured product is 10.0 mass% or less based on the total mass of the cured product.

[0010] If the moisture content of the hardened body is higher than 10.0 mass % relative to the total mass of the hardened body, it is difficult for the hardened body to have high bending strength and high bending toughness. The present inventors have discovered that a cured product of a curable composition containing a specific aluminosilicate source (A), a specific proportion of an alkali activator (B), and an alkali-resistant fiber (C) can have both high bending strength and high dimensional stability by having a moisture content of 10.0 mass% or less, based on the total mass of the cured product. The moisture content of the cured product can be adjusted to 10.0 mass% or less, for example, by drying the undried cured product obtained after curing using the method described below. Drying an undried cured product typically results in cracks on the surface and inside of the undried cured product, particularly at relatively high temperatures (e.g., temperatures above 100°C), resulting in a decrease in the mechanical strength of the cured product. In particular, undried cured products not reinforced with fibers suffer from numerous cracks, resulting in a significant decrease in the mechanical strength of the cured product. However, in the present invention, the cured product is based on a curable composition having a specific composition, which not only avoids this decrease in mechanical strength but also appears to have improved mechanical strength. That is, it is believed that drying (preferably at a relatively high temperature) allows the curing reaction to proceed substantially completely and further densifies the fibers and the polymer matrix, thereby enhancing the fiber reinforcing effect and resulting in high bending strength and bending toughness of the cured product. However, the above is merely a guess, and the present invention is not limited to these mechanisms of action.

[0011] The moisture content of the hardened body is preferably 9.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less, based on the total mass of the hardened body. When the moisture content of the hardened body is equal to or less than the above upper limit, it is easy to obtain a hardened body with higher bending strength and higher bending toughness. The moisture content of the hardened body can be adjusted to a value equal to or less than the above upper limit, for example, by drying the undried hardened body obtained after curing using the method described below. The lower limit of the moisture content of the hardened body is not particularly limited. The moisture content of the hardened body may be 0% by mass. The moisture content of the hardened body can be measured by the method described in the Examples described below.

[0012] <(A) Aluminosilicate Source> The aluminosilicate source (A) contains aluminosilicate (xM2O·yAl2O3·zSiO2·nH2O, where M is an alkali metal) as its main component. Here, the term "main component" refers to the component with the largest mass in the aluminosilicate source. When the aluminosilicate source comes into contact with a highly alkaline solution (aqueous solution of alkaline activator (B)), cations such as aluminum and silicon are eluted, and these undergo polycondensation to form a strong SiO4·AlO4 polymer network (geopolymer).

[0013] The aluminosilicate source (A) contains blast furnace slag, and the blast furnace slag content is 40% by mass or more based on the total solid content of the aluminosilicate source (A). If the blast furnace slag content is less than 40% by mass, it is difficult for the hardened body to have high bending strength, high bending toughness, and high dimensional stability. The blast furnace slag content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, particularly preferably 70% by mass or more, and may even be 100% by mass, based on the total solid content of the aluminosilicate source (A). If the blast furnace slag content is equal to or greater than the lower limit, the resulting hardened body tends to have a denser structure, making it easier to obtain a hardened body with higher bending strength, higher bending toughness, and higher dimensional stability. Furthermore, because blast furnace slag is a cheaper raw material than metakaolin and the like, the use of blast furnace slag has an advantage in terms of production costs.

[0014] Blast furnace slag includes crystalline slowly cooled slag and amorphous granulated slag, both of which can be used in the present invention. Granulated slag is preferred because it is more likely to further improve the strength of the hardened body or promote curing.

[0015] Suitable examples of the aluminosilicate source (A) other than blast furnace slag include industrial wastes such as fly ash, red mud, and sewage sludge incineration ash; natural aluminosilicate minerals and their calcined products (e.g., metakaolin); and volcanic ash. These substances are commercially available, and in the present invention, they may be used alone or in combination of two or more.

[0016] In one embodiment of the present invention, the aluminosilicate source (A) further includes, in addition to blast furnace slag, at least one selected from the group consisting of fly ash, metakaolin, and red mud. This embodiment facilitates the production of a hardened body with higher densification than when blast furnace slag is used alone as the aluminosilicate source (A), thereby making it easier to obtain a hardened body with higher bending strength, higher bending toughness, and higher dimensional stability. In this embodiment, the content of at least one selected from the group consisting of fly ash, metakaolin, and red mud is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, based on the total solid content of the aluminosilicate source (A). The content of the blast furnace slag is preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on the total solid content of the aluminosilicate source (A).

[0017] The specific surface area of ​​the blast furnace slag is preferably 1000 to 9000 cm 2 / g, more preferably 2000 to 8000 cm 2 / g or more, more preferably 3000 to 7000 cm 2 / g. When the specific surface area of ​​blast furnace slag is equal to or greater than the lower limit and equal to or less than the upper limit, the blast furnace slag is likely to have sufficient reaction sites and a suitable average particle size, and as a result, the hardened body produced is likely to have higher bending strength, higher bending toughness, and higher dimensional stability. The specific surface area of ​​blast furnace slag can be adjusted to be equal to or greater than the lower limit and equal to or less than the upper limit, for example, by crushing and classifying the blast furnace slag and using a specific fraction. The specific surface area of ​​blast furnace slag can be measured, for example, by laser diffraction / scattering.

[0018] The content of the aluminosilicate source (A), based on the total solid content of the curable composition, is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, particularly preferably 40% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and particularly preferably 60% by mass or less. The cured body of the present invention is usually produced by a method including a step of molding the curable composition. When the cured body is produced by, for example, a casting method or an extrusion molding method, the content of the aluminosilicate source (A), based on the total solid content of the curable composition, is preferably 25% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. When the content of the aluminosilicate source (A) is at least the above-mentioned lower limit and at most the above-mentioned upper limit, a cured body having higher flexural strength, higher flexural toughness, and higher dimensional stability is likely to be obtained.

[0019] <(B) Alkaline activator> The alkaline activator (B) used in the present invention exhibits high alkalinity in water, and upon contact with the aluminosilicate source (A), activates it and dissolves cations such as Al and Si. The content of the alkali activator (B) is 10% by mass or less based on the total solid content of the curable composition. If the content of the alkali activator (B) is more than 10% by mass, it is difficult to obtain high dimensional stability of the cured product.

[0020] Examples of the alkaline activator (B) include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, and alkali metal carbonates such as sodium carbonate, potassium carbonate, and lithium carbonate, which may be used alone or in combination of two or more. When the curable composition of the present invention contains these exemplified alkali activators (B), the content thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and 10% by mass or less, preferably 9% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less, based on the total solid content of the curable composition. When this content is at least the above-mentioned lower limit and at most the above-mentioned upper limit, activation of the aluminosilicate source (A) is facilitated, and the produced cured body is likely to have higher flexural strength, higher flexural toughness, and higher dimensional stability.

[0021] Another example of the alkaline activator (B) is an alkali metal silicate, which not only activates the aluminosilicate source (A) when it comes into contact with it, but also serves as a source of the silicic acid monomer [Si(OH)4] that forms the geopolymer.

[0022] Suitable examples of alkali metal silicates include sodium silicate, potassium silicate, and lithium silicate, and in the present invention, these may be used alone or in combination of two or more. From the viewpoint of low cost, it is preferable to use sodium silicate. Furthermore, a portion of the sodium silicate may be replaced with potassium silicate within a range that does not impair the advantage of production cost. Sodium silicate may be used in the form of water glass (a concentrated aqueous solution of sodium silicate) obtained by dissolving sodium silicate in water and heating the mixture.

[0023] Alkali metal silicates are usually used in the form of an aqueous solution. The alkali metal / water molar ratio in the alkali metal silicate aqueous solution is preferably 0.02 or more. A higher molar ratio is preferable because the strength of the resulting cured body increases with increasing molar ratio. However, the less water there is, the lower the fluidity of the curable composition containing the aluminosilicate source (A), alkali activator (B), and alkali-resistant fiber (C), making molding more difficult. Therefore, the molar ratio is preferably 0.03 to 0.20, more preferably 0.04 to 0.15, and particularly preferably 0.06 to 0.12.

[0024] When the curable composition of the present invention contains an alkali metal silicate as the alkali activator (B), its content is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and 10% by mass or less, preferably 8% by mass or less, more preferably 7% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5% by mass or less, based on the total solid content of the curable composition. When this content is at least the lower limit and at most the upper limit, the produced cured product is likely to have higher bending strength, higher bending toughness, and higher dimensional stability.

[0025] The curable composition of the present invention may contain, as the alkali activator (B), a combination of the above-mentioned alkali metal hydroxide and / or alkali metal carbonate with the above-mentioned alkali metal silicate, preferably a combination of the above-mentioned alkali metal hydroxide with the above-mentioned alkali metal silicate. When the curable composition of the present invention contains such a combination as the alkali activator (B), a cured product having higher flexural strength, higher flexural toughness, and high dimensional stability is likely to be obtained.

[0026] When the curable composition of the present invention contains the above-mentioned combination as the alkali activator (B), its content is preferably 0.6 mass% or more, more preferably 1.5 mass% or more, even more preferably 3 mass% or more, and 10 mass% or less, preferably 9 mass% or less, more preferably 8 mass% or less, even more preferably 7 mass% or less, and particularly preferably 6 mass% or less, based on the total solid content of the curable composition. When this content is at least the above lower limit and at most the above upper limit, the produced cured product is likely to have higher bending strength, higher bending toughness, and higher dimensional stability.

[0027] <(C) Alkali-resistant fiber> The alkali-resistant fiber (C) used in the present invention has the effect of increasing the bending strength and bending toughness of the cured product. Furthermore, by suppressing cracks that may occur during the curing and drying process of the curable composition, it is possible to prevent a decrease in the bending strength and dimensional stability of the cured product.

[0028] The alkali-resistant fiber (C) may be either inorganic or organic, as long as it has chemical resistance to alkali. Examples of alkali-resistant inorganic fibers include alkali-resistant glass fibers, steel fibers, stainless steel fibers, and carbon fibers. Examples of alkali-resistant organic fibers include polyvinyl alcohol (hereinafter sometimes referred to as PVA) fibers, polyolefin fibers (e.g., polyethylene fibers and polypropylene fibers), ultra-high molecular weight polyethylene fibers, polyamide fibers (e.g., polyamide 6, polyamide 6,6, and polyamide 6,10), aramid fibers (e.g., para-aramid fibers), polyparaphenylene benzobisoxazole fibers (e.g., polyparaphenylene benzoxazole (PBO) fibers), nylon fibers, acrylic fibers, rayon fibers (e.g., polynosic fibers and solvent-spun cellulose fibers), polyphenylene sulfide fibers (PPS fibers), and polyether ether ketone fibers (PEEK fibers). These alkali-resistant fibers may be used alone or in combination of two or more.

[0029] Among these, polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers, and nylon fibers are preferably used because they can easily impart excellent reinforcement to the cured body and can be produced at low cost. Therefore, in one embodiment of the present invention, the alkali-resistant fiber (C) is preferably at least one selected from the group consisting of polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers, and nylon fibers.

[0030] The average fiber diameter of the alkali-resistant fiber (C) is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 250 μm or less, even more preferably 150 μm or less, and particularly preferably 75 μm or less. The average fiber diameter of the alkali-resistant fiber (C) is usually 3 μm or more, preferably 5 μm or more, and more preferably 7 μm or more. When the average fiber diameter of the alkali-resistant fiber (C) is not more than the above-mentioned upper limit, such alkali-resistant fiber (C) has sufficient fiber strength and is easily produced industrially in a stable manner. When the average fiber diameter of the alkali-resistant fiber (C) is not less than the above-mentioned lower limit, the fibers are easily dispersed more uniformly in the polymer matrix. Herein, in the present invention, the polymer matrix (hereinafter sometimes referred to as "matrix") refers to the polymer portion that binds the alkali-resistant fiber (C) in the cured product.

[0031] From the viewpoint of easily achieving both good dispersibility of the fibers in the curable composition and good reinforcing properties after curing of the curable composition, the alkali-resistant fiber (C) has an aspect ratio of preferably 15 or more, more preferably 30 or more, even more preferably 40 or more, particularly preferably 50 or more, and preferably 2500 or less, more preferably 2000 or less, even more preferably 1000 or less, particularly preferably 500 or less. Here, in the present invention, the aspect ratio means the ratio (L / D) of the fiber length L to the fiber diameter D.

[0032] The average fiber diameter and aspect ratio of the alkali-resistant fiber (C) can be determined in accordance with JIS L 1015 "Test method for chemical fiber staple (8.5.1)".

[0033] The average fiber length of the alkali-resistant fibers (C) is preferably 0.5 to 40 mm, more preferably 1 to 15 mm, from the viewpoint of easily achieving both good dispersibility of the fibers in the curable composition and good reinforcing properties of the curable composition after curing.

[0034] The tensile strength of the alkali-resistant fiber (C) in the present invention is preferably 3 cN / dtex or more, more preferably 5 cN / dtex or more, and particularly preferably 7 cN / dtex or more. When the tensile strength of the alkali-resistant fiber (C) is equal to or greater than the above-mentioned lower limit, the reinforcing performance of the cured body is more easily improved. The upper limit of the tensile strength of the alkali-resistant fiber (C) in the present invention is appropriately set depending on the type of fiber, but is, for example, 30 cN / dtex or less. The tensile strength can be determined in accordance with JIS L 1015 "Testing Method for Chemical Fiber Staples (8.5.1)".

[0035] When a PVA-based fiber, such as a vinylon fiber, is used as the alkali-resistant fiber (C), the PVA-based fiber may have the following properties. The degree of polymerization of the PVA-based polymer constituting the PVA-based fiber can be appropriately selected depending on the purpose and is not particularly limited. In consideration of the mechanical properties of the resulting fiber, the average degree of polymerization of the PVA-based polymer determined from the viscosity of an aqueous solution at 30°C is preferably about 500 to 20,000, more preferably about 800 to 15,000, and particularly preferably about 1,000 to 10,000. Among these, from the viewpoint of the strength of the resulting fiber, the average degree of polymerization of the PVA-based polymer is preferably 1,000 or more, more preferably 1,200 or more, more preferably 1,500 or more, and particularly preferably 1,750 or more. The PVA-based polymer may be a medium-degree of polymerization product with an average degree of polymerization of 1,000 to less than 3,000, or a high-degree of polymerization product with an average degree of polymerization of 3,000 or more.

[0036] The degree of saponification of the PVA-based polymer can also be appropriately selected depending on the purpose and is not particularly limited. From the viewpoint of the mechanical properties of the obtained fiber, the degree of saponification of the PVA-based polymer may be, for example, 95 mol% or more, preferably 98 mol% or more. The degree of saponification of the PVA-based polymer may be 99 mol% or more, or may be 99.8 mol% or more. When the degree of saponification of the PVA-based polymer is equal to or greater than the above-mentioned lower limit, the obtained fiber is likely to have good mechanical properties, processability, production costs, etc.

[0037] The PVA-based fibers used in the present invention are produced by dissolving such a PVA-based polymer in a solvent, spinning it by either a wet, dry-wet, or dry method, and then hot-drawing it. Wet spinning is a method in which the spinning dope is directly discharged from a spinning nozzle into a solidification bath. Dry-wet spinning is a method in which the spinning dope is once discharged from a spinning nozzle into air or an inert gas at a given distance and then introduced into a solidification bath. Dry spinning is a method in which the spinning dope is discharged into air or an inert gas. After spinning, the PVA-based fibers may be stretched as necessary. Furthermore, they may be subjected to acetalization or other treatments commonly performed on PVA-based fibers.

[0038] The solvent used in the spinning solution for PVA-based fibers is not particularly limited as long as it is capable of dissolving PVA. For example, water, dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, and polyhydric alcohols (e.g., glycerin, ethylene glycol, triethylene glycol, etc.) may be used alone or in combination. In the present invention, when wet spinning is performed, water or an organic solvent is preferably used as the solvent. Among these, water and DMSO are particularly preferred from the viewpoints of ease of supply and environmental impact. The polymer concentration in the spinning solution varies depending on the composition and degree of polymerization of the PVA-based polymer and the type of solvent, but is generally 6 to 60% by mass.

[0039] The above solvents may also be used in dry spinning, and in that case, either water or an organic solvent may be used.

[0040] The spinning dope may contain additives other than the PVA polymer depending on the purpose, as long as the effects of the present invention are not impaired. Examples of the additives include boric acid, surfactants, antioxidants, decomposition inhibitors, antifreeze agents, pH adjusters, masking agents, colorants, and oils.

[0041] The solvent used in the solidification bath may be selected appropriately depending on the type of solvent used in the spinning dope. When the spinning dope is an aqueous solution, the solidification bath may be an aqueous solution of an inorganic salt (e.g., sodium sulfate, ammonium sulfate, sodium carbonate, sodium hydroxide, etc.) capable of solidifying a PVA-based polymer, or an alkaline aqueous solution. When the spinning dope is an organic solvent solution, the solidification bath may be an organic solvent capable of solidifying a PVA-based polymer, such as an alcohol (e.g., methanol, ethanol, propanol, butanol, etc.), or a ketone (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.).

[0042] In the present invention, PVA fibers obtained by dry spinning or PVA fibers obtained by wet spinning from a spinning solution containing water or an organic solvent as the solvent are preferred from the viewpoint of fiber tensile strength.

[0043] In order to extract and remove the solvent of the spinning dope from the solidified raw yarn, the raw yarn may be passed through an extraction bath, and the raw yarn may be wet-stretched simultaneously during extraction. After wet stretching, the fiber may be dried and, if necessary, further subjected to hot stretching. When stretching is performed, the total stretch ratio (the product of the wet stretching ratio and the stretch ratio after drying) may be, for example, 5 to 25 times, preferably about 8 to 20 times.

[0044] Commercially available fibers may be used as the alkali-resistant fiber (C), and examples thereof include organic fibers such as polyvinyl alcohol fibers manufactured by Kuraray Co., Ltd., polypropylene fibers manufactured by Valchip Corporation, and nylon fibers manufactured by Toray Industries, Inc., and inorganic fibers such as glass fibers manufactured by Nippon Electric Glass Co., Ltd. and Pacific Materials Corporation.

[0045] In one embodiment of the present invention, the content of the alkali-resistant fiber (C) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, based on the total solids content of the cured product, and is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the content of the alkali-resistant fiber is at least the above-mentioned lower limit and at most the above-mentioned upper limit, the produced cured product is likely to have higher bending strength and higher bending toughness. The content of the alkali-resistant fiber (C) in the cured product can be measured by the method described in the Examples below.

[0046] <(D) Slag stimulant> The hardened product of the present invention may further contain a slag stimulant (D). Adding the slag stimulant (D) to the hardenable composition of the present invention makes it easier to obtain a hardened product with higher flexural strength and / or higher flexural toughness. Furthermore, the curing time can be shortened, and even with a shortened curing time, it is easier to obtain a hardened product with higher flexural strength and / or higher flexural toughness.

[0047] Examples of the slag stimulant (D) include aluminum sulfate, calcium hydroxide, sodium sulfate, and sodium aluminate, which may be used alone or in combination of two or more. Among these, from the viewpoint of easily obtaining high bending toughness or high dimensional stability, it is preferable that the hardened body contains one or more selected from the group consisting of aluminum sulfate, calcium hydroxide, and sodium aluminate.

[0048] When the hardened body of the present invention contains a slag stimulant (D), its content is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and is preferably 3% by mass or less, more preferably 2.5% by mass or less, even more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, based on the total solid content of the hardened body. When the content is at least the lower limit and at most the upper limit, the effects of adding the slag stimulant (D) described above can be easily obtained.

[0049] <(E) Aggregate> The hardened body of the present invention may further contain an aggregate (E). When the hardened body of the present invention contains aggregate (E), the content thereof is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, particularly preferably 40% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, particularly preferably 60% by mass or less, based on the total solid content of the hardened body. Therefore, in a preferred embodiment of the present invention, the hardened body further contains aggregate (E), and the content of aggregate (E) is 15% by mass or more and 75% by mass or less based on the total solid content of the hardened body. When the content is equal to or greater than the lower limit and equal to or less than the upper limit, the above-mentioned effect of adding the aggregate (E) can be easily obtained.

[0050] The aggregate (E) may be any aggregate commonly used in concrete or mortar. The aggregate (E) is different from the aluminosilicate source (A) described above. Aggregates are classified into fine aggregate and coarse aggregate depending on particle size, natural aggregate and artificial aggregate depending on origin, and lightweight aggregate, normal aggregate and heavy aggregate depending on density. These aggregates may be used alone or in combination of two or more types.

[0051] The fine aggregate may be one having a particle size of 5 mm or less, and examples thereof include sands having a particle size of 5 mm or less; fine aggregates obtained by powdering or granulating inorganic materials such as silica stone, slag, slag particles, various sludges, and rock minerals. Examples of sands include river sand, mountain sand, sea sand, crushed sand, silica sand, slag, glass sand, iron sand, ash sand, calcium carbonate, and artificial sand. These fine aggregates may be used alone or in combination of two or more.

[0052] Coarse aggregate is aggregate containing particles with a particle size of 5 mm or more at 85% by mass or more based on the total amount of coarse aggregate. Coarse aggregate may also be composed of particles with a particle size greater than 5 mm. Examples of coarse aggregate include various types of gravel, artificial aggregate, and recycled aggregate (such as recycled aggregate from construction waste). These coarse aggregates may be used alone or in combination of two or more types.

[0053] Examples of lightweight aggregates include natural lightweight aggregates such as volcanic gravel, expanded slag, and charcoal husk, as well as artificial lightweight aggregates such as expanded perlite, expanded black rock, vermiculite, shirasu balloons, and fly ash microballoons. These lightweight aggregates may be used alone or in combination of two or more.

[0054] Furthermore, the hardened body of the present invention may further contain a functional aggregate in addition to the aggregate (E). Examples of functional aggregates include colored aggregates, hard aggregates, elastic aggregates, and aggregates having a specific shape, and specific examples include layered silicates (e.g., mica, talc, and kaolin), alumina, and silica. The ratio of functional aggregate to aggregate can be appropriately set depending on the type of aggregate. For example, the mass ratio of aggregate to functional aggregate (aggregate / functional aggregate) may be 99 / 1 to 70 / 30, preferably 98 / 2 to 75 / 25, and more preferably 97 / 3 to 80 / 20. These functional aggregates may be used alone or in combination of two or more types.

[0055] <(F) Other powders> The hardened body of the present invention may further contain, as other powders (F), powders other than the aluminosilicate source (A) and aggregate (E). Examples of other powders (F) include fine powders (e.g., silica fume, slaked lime, quicklime, alumina, bentonite, etc.), calcium sulfate derivatives (e.g., gypsum dihydrate, α-type or β-type hemihydrate, and anhydrous gypsum), foaming agents (e.g., aluminum powder, etc.), foaming aids (e.g., metal soaps such as metal stearates and metal palmitates), and fluidizers (e.g., sodium gluconate, sodium L-tartrate, etc.). These may be used alone or in combination. Among these, from the viewpoint of easily achieving high bending strength and high dimensional stability, it is preferable for the hardened body to contain one or more selected from the group consisting of silica fume, calcium sulfate derivatives, and fluidizers. In particular, it is preferable for the hardened body to contain calcium sulfate derivatives, as this helps to suppress cracking in the hardened body. Furthermore, if the curable composition contains a fluidizing agent, the usable time of the cured composition can be extended, which is preferable because it makes it easier to mix the fibers uniformly. Also, by using a foaming agent or foaming assistant, or by increasing the amount of other powder (F), the cured product can be made lighter.

[0056] When the cured product of the present invention contains other powders (F), the content thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, based on the total solid content of the cured product, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, particularly preferably 20% by mass or less, and especially preferably 15% by mass or less. In another embodiment, the content is also preferably 10% by mass or less, 7% by mass or less, 5% by mass or less, or 3% by mass or less. When the content is at least the lower limit and at most the upper limit, the effects of adding the other powders (F) described above are easily obtained.

[0057] In a preferred embodiment of the present invention, the hardened body further contains a calcium sulfate derivative, and the content of the calcium sulfate derivative is 0.01% by mass or more, more preferably 0.1% by mass or more, and 20% by mass or less, more preferably 15% by mass or less, based on the total solid content of the hardened body. In another embodiment, the content is preferably 3% by mass or less, or 2% by mass or less.

[0058] <(G) Molding Aids> The cured product of the present invention is usually produced by a method including a step of molding the curable composition. Therefore, if necessary, a molding aid (G) may be added to the curable composition. Addition of the molding aid (G) can reduce molding unevenness of the curable composition.

[0059] Examples of the molding aid (G) include pulp, thickeners (e.g., water-soluble polymeric substances such as cellulose ethers (e.g., methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose), polyvinyl alcohol, polyacrylic acid, and lignin sulfonates), and various admixtures (e.g., air-entraining agents, superplasticizers, water-reducing agents, high-performance water-reducing agents, air-entraining agents, high-performance air-entraining agents, water-retention agents, water-repellents, expanding agents, and hardening accelerators). These may be used alone or in combination of two or more. When the molding aid (G) is added to the curable composition, the addition rate is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5% by mass or less, based on the total solids content of the curable composition. When the addition rate is at least the lower limit and at most the upper limit, the effects of adding the molding aid described above are easily achieved.

[0060] If fibers aggregate in the cured body, the physical properties will be reduced at those locations, so reducing the fiber aggregation degree is important for obtaining high bending strength and high dimensional stability of the cured body. The fiber aggregation degree of the cured body is preferably 10% or less, more preferably 8% or less, and even more preferably 6% or less. The lower limit of the fiber aggregation degree may be 0% or more. The fiber aggregation degree in this specification is determined by the method described in the Examples below. If the fiber aggregation degree is not more than the above upper limit, the mechanical strength of the final molded body is likely to be improved.

[0061] The coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces cut out from the whole or part of the cured body so as to weigh 10 g is preferably 30% or less, more preferably 25% or less, and particularly preferably 20% or less. The smaller the coefficient of variation of the average content of the alkali-resistant fiber (C), the more uniformly the alkali-resistant fiber (C) dispersed in the cured body, and therefore the more stable the quality and the greater the strength of the cured body. The coefficient of variation is determined by the method described in the Examples below.

[0062] The bending proportional limit strength of the hardened body measured in accordance with JIS A 1408 is preferably 3N / mm 2 More than 5N / mm 2 More preferably, 5.5N / mm 2 More preferably, 6N / mm 2 More than 7N / mm 2 The upper limit of the bending proportional limit strength is not particularly limited. The bending proportional limit strength is usually 30 N / mm 2 The following is the result.

[0063] The maximum bending strength of the cured product measured in accordance with JIS A 1408 is preferably 3N / mm 2 More than 5N / mm 2 More preferably, 7N / mm 2 The upper limit of the maximum bending strength is not particularly limited. The maximum bending strength is usually 50 N / mm 2The following is the result.

[0064] The bending toughness of the cured product measured in accordance with JIS A 1408 is preferably 50 N / mm or more, more preferably 100 N / mm or more, and even more preferably 200 N / mm or more. There is no particular upper limit to the bending toughness. The bending toughness is usually 1500 N / mm or less.

[0065] The dimensional change rate of the cured product measured in accordance with JIS A 5430 is preferably 0.12% or less, more preferably 0.10% or less, and even more preferably 0.08% or less.

[0066] <Method of manufacturing the hardened body> The cured product of the present invention may be, for example, mixing components including an aluminosilicate source (A) and an alkaline activator (B) together with water; A step of adding alkali-resistant fiber (C) to the obtained mixture and further mixing to prepare a curable composition; A step of forming, curing, and drying the obtained curable composition to obtain a cured product. It can be produced by a method comprising:

[0067] When the optional slag stimulator (D), aggregate (E), other powders (F), and molding aid (G) are used, these optional components can be added in the initial mixing step in which the components including the aluminosilicate source (A) and alkali activator (B) are mixed with water. The aluminosilicate source (A), alkali activator (B), and alkali-resistant fiber (C), as well as the optionally used slag stimulator (D), aggregate (E), other powders (F), and molding aid (G) used in this production method may be those described above in the sections <(A) Aluminosilicate Source>, <(B) Alkali Activator>, <(C) Alkali-Resistant Fiber>, <(D) Slag Stimulator>, <(E) Aggregate>, <(F) Other Powders>, and <(G) Molding Aid>, respectively.

[0068] The mixing method in the initial mixing step is not particularly limited, and mixing can usually be carried out at room temperature (e.g., 25°C) using a known or conventional mixer or the like (e.g., a mortar mixer, a tilting mixer, a truck mixer, a twin-screw mixer, an omni mixer, a pan mixer, a planetary mixer, an Eirich mixer, etc.). The order in which the components are added to the mixer or the like is also not particularly limited. The amount of water is also not particularly limited, but from the viewpoint of easily obtaining a uniform curable composition without containing excessive water, it is usually 30 to 300 parts by mass per 100 parts by mass of the aluminosilicate source (A). Water may be added independently, or, when water glass is used as the alkali activator (B), it may be added in the form of water as its solvent. A water-soluble substance (e.g., the alkali activator (B), and, if added, a water-soluble optional component (e.g., aluminum sulfate as the slag activator (D)) may be dissolved in water to prepare an aqueous solution, and the resulting aqueous solution may then be mixed with a water-insoluble component (e.g., the aluminosilicate source (A), and, if added, a water-insoluble optional component (e.g., aggregate (E)). In this case, the aqueous solution may be mixed with a mixture obtained by separately mixing the water-insoluble component. Furthermore, the mixing time is not particularly limited, and mixing may be continued until a uniform mixture is obtained.

[0069] Next, the alkali-resistant fiber (C) is added to the obtained mixture and further mixed. The alkali-resistant fiber (C) may be added in a predetermined amount all at once or in two or more portions. To easily obtain a uniform curable composition, the alkali-resistant fiber (C) is preferably added in a unidirectionally aligned and converged state. The mixing time after adding the fiber is not particularly limited, and mixing may be continued until a uniform curable composition is obtained. Furthermore, the temperature of the mixture during mixing is also important for uniformly mixing the alkali-resistant fiber (C). The temperature of the mixture is preferably 10 to 50°C, more preferably 15 to 40°C, and even more preferably 20 to 35°C. When the temperature of the mixture is equal to or higher than the lower limit and equal to or lower than the upper limit, the fibers are easily mixed uniformly.

[0070] Subsequently, after molding the obtained curable composition, the curable composition is cured so that it can withstand manufacturing steps such as demolding and transportation. In the manufacturing method of the present invention, the obtained curable composition can be molded using known techniques, such as a casting method in which the curable composition is poured into an open mold; a dehydration molding method in which the curable composition is dehydrated by pressing or suction; an injection molding method in which the curable composition is injected into a closed mold; or an extrusion molding method in which a product of a specific shape can be molded through a die. In the extrusion molding method, a vacuum extruder may be used. Furthermore, during molding, pressure and / or vibration may be applied as necessary, or the curable composition may be pressed using a top mold or roll. Curing may typically be performed under normal pressure or pressure, at a temperature of 20 to 95°C, for example, 25°C or 90°C, and a relative humidity of 20 to 99%. The curing time is appropriately set depending on the pressure, temperature, and / or humidity at which curing is performed. The higher the pressure, temperature, and humidity, the shorter the curing time can be, and the lower the pressure, temperature, and humidity, the longer the curing time can be. For example, when performing atmospheric steam curing (wet curing) at a temperature of 80°C and a humidity of 90% or more, curing can be performed for approximately 4 to 24 hours. The curable composition hardens during curing. Additional curing may be performed thereafter, and in this case, the curing conditions for the additional curing may be the same as or different from those for the initial curing.

[0071] The undried hardened body obtained after curing is dried until a predetermined moisture content is achieved. The hardened body having a specific moisture content can have both high bending strength and high dimensional stability.

[0072] The drying temperature is preferably 60°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably a temperature higher than 100°C (for example, 105°C or higher), from the viewpoint of easily obtaining higher bending strength and higher bending toughness. The drying temperature is preferably 250°C or lower, more preferably 200°C or lower, and particularly preferably 160°C or lower, from the viewpoint of easily avoiding the problem of cracking caused by an excessively high temperature. The drying time may be appropriately selected depending on the size or shape of the undried cured body, the drying temperature, etc.

[0073] The method for drying the undried cured product is not particularly limited. For example, it can be dried using a hot air drying method. To dry efficiently, it is preferable to raise the temperature inside the dryer over a certain period of time (e.g., 30°C / h) to uniformly raise the temperature of the cured product to be dried, and then dry it at a predetermined drying temperature for a predetermined time.

[0074] The obtained cured product has a specific water content based on a curable composition having excellent uniformity due to its specific composition, and it is believed that production by the above method allows the curing reaction to proceed substantially completely, resulting in further densification of the fibers and polymer matrix, and therefore the cured product can have both high bending strength and high dimensional stability. [Example]

[0075] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The physical properties in the examples and comparative examples were measured or evaluated by the following methods.

[0076] [Moisture content of hardened body] To maintain a constant initial moisture content when measuring the moisture content of the hardened body, the hardened body was dried for 72 hours in a dryer set at 40°C, and the mass of the hardened body was measured. This mass was designated as the reference mass W1 (g) of the hardened body. Next, the cured body was dried for 24 hours in a dryer set at 100°C, and the mass W2 (g) of the cured body was measured. The moisture content X (mass%) of the cured body was calculated using the following formula.

number

[0077] [Flexural strength and flexural toughness of hardened product] To maintain a constant moisture content when measuring the flexural strength and flexural toughness of the cured specimens, the specimens were dried for 72 hours in a dryer set at 40°C. The flexural strength and flexural toughness of the cured specimens were then measured in accordance with JIS A 1408. Flexural strength was measured using a Shimadzu Autograph "AG-50kNX" with a central loading method, a bending span of 14.6 cm, and a test speed (loading head speed) of 2 mm / min. In Table 5, LOP and MOR refer to the proportional limit strength and maximum flexural strength, respectively.

[0078] [Measurement method for dimensional change rate] The dimensional change rate of the cured product was measured in accordance with JIS A 5430. First, the cured specimen to be measured was placed in a dryer and maintained at 60°C ± 3°C for 24 hours, after which it was removed. The removed cured specimen was placed in a desiccator conditioned with silica gel and allowed to cool to 20°C ± 1.5°C. Next, milky-colored glass was attached to the cured specimen, and gauge lines were inscribed so that the distance between the gauge lines was approximately 140 mm. The length between the gauge lines was measured using a comparator with an accuracy of 1 / 500 mm, and this length was designated L1 (mm). The cured specimen was then placed on a stand so that its length was horizontal, and immersed in water at 20°C ± 1.5°C with its top end positioned approximately 30 mm below the water surface. After 24 hours, the cured specimen was removed from the water, the water adhering to the surface was wiped off, and the length between the gauge lines was measured again, designated L2 (mm). The dimensional change Y (%) due to water absorption was calculated using the following formula:

number

[0079] [Alkali-resistant fiber (C) content and coefficient of variation of average content] Pieces of 10 g each were cut out from the hardened body, and 11 pieces were randomly selected from the cut pieces. After drying at 105°C for 3 hours, the weights of each cut piece (W1 to W 11 (g)) was measured. One of the 11 pieces was crushed in a mortar.11 The following description is given assuming that a cut piece having a weight of (g) was crushed. After crushing, water was added to the crushed material and filtered through a 10-mesh wire net to separate the alkali-resistant fiber (C) from the matrix. The filtrate was then further filtered through filter paper to recover the matrix, which was then dried at 105°C for 3 hours. The weight of the matrix, W 11-1 Then, the matrix was placed in a muffle furnace at 600°C for 30 minutes, and cooled to the weight of the matrix W 11-2 The weight loss (g) of the matrix was measured and the weight loss rate X (%) was calculated using the following formula.

number

number

number

[0080] [Fiber cohesion in hardened body] A 100g piece was cut out from the cured body and crushed in a mortar. After crushing, water was added to the crushed material and filtered through a 10-mesh wire mesh to separate the alkali-resistant fiber (C) from the matrix. From the fibers remaining on the wire mesh, fiber balls (aggregates of 20 or more fibers in bundles or clumps) formed by the aggregation of fibers were removed with tweezers, and the fibers remaining on the wire mesh were also removed. Each fiber was dried for 24 hours in a dryer set at 100°C, and the mass W of the dispersed fibers was determined. a (g), the mass of the fiber ball formed by the aggregation of fibers W b The fiber cohesion (the ratio of the mass of the fiber balls to the total mass of the alkali-resistant fiber (C) contained in the cured body) was calculated using the following formula.

number

[0081] [Example 1] Curable compositions were prepared using the materials shown in Tables 1 and 2 below in the proportions shown in Table 2, and cured products of the obtained curable compositions were manufactured. Specifically, sodium hydroxide was first dissolved in water in an amount equivalent to 35% by mass relative to the total mass of the aluminosilicate source (A) and other powders (F) to prepare a solution of the alkali activator (B). Next, granulated blast furnace slag (Fine Cerament 20A: specific surface area 6000 cm), which was the aluminosilicate source (A), was added. 236.8% by mass of sintered silica (1000 kJ / g), 9.7% by mass of fly ash (Shiden Business Co., Ltd.: Shiden Fly Ash Type II), 2.0% by mass of silica fume (Tomoe Engineering Co., Ltd.: EFACO Silica Fume) as other powder (F), and 48.0% by mass of sand (Tohoku Silica Sand Co., Ltd.: No. 5 silica sand and Tohoku Silica Sand Co., Ltd.: No. 7 silica sand in a 2:1 mass ratio) as aggregate (E) were added to a mortar mixer and mixed for 1 minute. The alkali activator solution was then added to the mortar mixer and mixed for 1 minute. Next, 0.1% by mass of sodium gluconate as other powder (F) was added to the mortar mixer and mixed for an additional 3 minutes. Next, 0.7% by mass of PVA fiber (Kuraray Co., Ltd.: polyvinyl alcohol fiber, hereafter referred to as "PVA1"), which was aligned and converged in one direction, was added to the mortar mixer as alkali-resistant fiber (C), and mixed for an additional 1 minute to obtain a curable composition. The resulting curable composition was poured into a mold measuring 4 cm wide x 18 cm long x 1 cm thick, and cured for 24 hours under normal pressure at 90°C and 95% RH. The mold was then demolded and dried for 4 hours in a constant temperature air-blowing dryer set at 110°C to produce a cured product. The cured product was evaluated as described above, and the results are shown in Table 5.

[0082] [Examples 2 to 3] A cured product was produced and evaluated in the same manner as in Example 1, except that the drying conditions were changed to those shown in Table 2.

[0083] [Example 4] As shown in Table 2, the proportion of alkali-resistant fiber was changed from 0.7% by mass to 1.4% by mass, and the proportion of blast furnace slag and the proportion of sand as aggregate (E) were accordingly changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 2.

[0084] [Example 5] As shown in Table 2, the type and proportion of alkali-resistant fiber were changed, and accordingly, the proportion of blast furnace slag, the proportion of fly ash, the proportion of silica fume, and the proportion of sand as aggregate (E) were changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 2.

[0085] [Example 6] As shown in Table 2, the type and proportion of alkali-resistant fiber were changed, and the proportion of blast furnace slag and the proportion of fly ash were accordingly changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 2.

[0086] [Example 7] As shown in Table 2, the type and proportion of alkali-resistant fiber were changed, and the proportion of blast furnace slag was accordingly changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 2.

[0087] [Example 8] As shown in Table 2, the proportion of blast furnace slag and the proportion of fly ash were changed, and the proportion of sand, which is aggregate (E), was accordingly changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 2.

[0088] [Example 9] A hardened body was produced and evaluated in the same manner as in Example 2, except that instead of preparing a solution of alkali activator (B) by dissolving sodium hydroxide in water in an amount equivalent to 35 mass% relative to the total mass of the aluminosilicate source (A) and other powders (F), a solution of alkali activator (B) was prepared by dissolving sodium hydroxide and water glass No. 3 in water in an amount equivalent to 30 mass% relative to the total mass of the aluminosilicate source (A) and other powders (F), and the proportions of each material other than the alkali-resistant fiber (C) and sodium gluconate were changed.

[0089] [Example 10] A cured product was produced and evaluated in the same manner as in Example 9, except that the drying conditions were changed to those shown in Table 2.

[0090] [Example 11] As shown in Table 2, hardened bodies were produced and evaluated in the same manner as in Example 9, except that blast furnace slag, fly ash, and metakaolin were used instead of the blast furnace slag and fly ash used as the aluminosilicate source (A), and the proportions of each material other than the alkali-resistant fiber (C) and aggregate (E) were changed.

[0091] [Example 12] A cured product was produced and evaluated in the same manner as in Example 11, except that the drying conditions were changed to those shown in Table 2.

[0092] [Example 13] A hardened body was produced and evaluated in the same manner as in Example 2, except that instead of adding the aluminosilicate source (A), granulated blast furnace slag and fly ash, the other powder (F), silica fume, and aggregate (E), to the mortar mixer, aluminum sulfate, the slag stimulant (D), was added to the mortar mixer in addition to the above materials, and the ratio of the granulated blast furnace slag and aggregate (E) was changed.

[0093] [Example 14] A hardened body was produced and evaluated in the same manner as in Example 13, except that the curing time was changed from 12 hours to 24 hours.

[0094] [Example 15] As shown in Table 2, the proportion of aluminum sulfate, which is the slag stimulant (D), was changed, and the proportion of blast furnace slag and the proportion of sand, which is the aggregate (E), were accordingly changed. In the same manner as in Example 14, the hardened bodies were produced and evaluated.

[0095] [Example 16] As shown in Table 2, the proportion of aluminum sulfate, which is the slag stimulant (D), was changed, and the proportions of blast furnace slag, fly ash, silica fume, and sand, which is the aggregate (E), were accordingly changed. In the same manner as in Example 14, hardened bodies were produced and evaluated.

[0096] [Example 17] A hardened body was produced and evaluated in the same manner as in Example 2, except that instead of preparing a solution of alkali activator (B) by dissolving sodium hydroxide in water in an amount equivalent to 35 mass% of the total mass of the aluminosilicate source (A) and other powders (F), a solution of alkali activator (B) was prepared by dissolving sodium hydroxide and water glass No. 3 in water in an amount equivalent to 30 mass% of the total mass of the aluminosilicate source (A), slag activator (D), and other powders (F), and the proportions of each material other than the alkali-resistant fiber (C) and sodium gluconate were changed.

[0097] [Example 18] A cured product was produced and evaluated in the same manner as in Example 17, except that the drying conditions were changed to those shown in Table 2.

[0098] [Example 19] A hardened body was produced and evaluated in the same manner as in Example 2, except that instead of charging granulated blast furnace slag and fly ash as the aluminosilicate source (A), silica fume as the other powder (F), and aggregate (E) into the mortar mixer, gypsum dihydrate as the other powder (F) was charged into the mortar mixer in addition to the above materials, and the proportion of aggregate (E) was changed.

[0099] [Example 20] As shown in Table 2, the proportion of gypsum dihydrate was changed, and accordingly the proportion of blast furnace slag and the proportion of sand as aggregate (E) were changed. In the same manner as in Example 19, except that, hardened bodies were produced and evaluated.

[0100] [Example 21] As shown in Table 2, the proportion of gypsum dihydrate was changed, and accordingly, the proportion of blast furnace slag, the proportion of fly ash, and the proportion of sand as aggregate (E) were changed. Except for this, hardened bodies were produced and evaluated in the same manner as in Example 19.

[0101] [Example 22] A hardened body was produced and evaluated in the same manner as in Example 2, except that instead of adding the aluminosilicate source (A), granulated blast furnace slag and fly ash, the other powder (F), silica fume, and aggregate (E), to the mortar mixer, aluminum sulfate, the slag stimulant (D), and gypsum dihydrate, the other powder (F), were added to the mortar mixer in addition to the above materials, and the ratios of the granulated blast furnace slag, fly ash, and aggregate (E) were changed.

[0102] [Example 23] An alkaline activator solution was prepared by dissolving sodium hydroxide in water in an amount equivalent to 54% by mass relative to the total mass of the aluminosilicate source (A), other powders (F), and molding aids (G). Next, granulated blast furnace slag (Fine Cerament 20A: specific surface area 6000 cm), which is the aluminosilicate source (A), was added. 2 The following materials were added to an Eirich mixer and mixed for 1 minute: 36.8% by weight of cellulose acetate (C10 / g), 9.9% by weight of fly ash (Shiden Business Co., Ltd.: Shiden Fly Ash Type II), 2.0% by weight of silica fume (Tomoe Engineering Co., Ltd.: EFACO Silica Fume) as other powder (F), 2.0% by weight of pulp (LBKP) and 0.7% by weight of thickener (carboxymethyl cellulose) as molding aids (G), and 42.9% by weight of sand (Tohoku Silica Sand Co., Ltd.: No. 5 silica sand and Tohoku Silica Sand Co., Ltd.: No. 7 silica sand in a 2:1 ratio). The resulting coarsely kneaded material and 0.1% by weight of sodium gluconate as other powder (F) were added to a two-roll kneader and mixed for 4 minutes. Next, 0.8% by mass of PVA fiber (polyvinyl alcohol fiber, "PVA2" manufactured by Kuraray Co., Ltd.) was added to the two-roll kneader and mixed for an additional 2 minutes. The clay-like mixture was extruded into a 30 cm wide, 1 cm thick plate using a vacuum extruder under a reduced pressure of 740 mmHg. The resulting plate was covered with a vinyl sheet and aged for 24 hours under normal pressure at 90°C and 95% RH. This was then dried for 8 hours in a constant temperature air-blowing dryer set at 110°C, after which it was cut into a 4 cm wide x 18 cm long piece to produce a cured product. The cured product was evaluated as described above, and the results are shown in Table 5.

[0103] [Example 24] A hardened body was produced and evaluated in the same manner as in Example 23, except that the curing time was changed from 12 hours to 24 hours.

[0104] [Example 25] As shown in Table 3, hardened bodies were produced and evaluated in the same manner as in Example 2, except that the proportions of blast furnace slag, fly ash, sodium hydroxide (alkali activator (B)), and sand (aggregate (E)) were changed.

[0105] [Examples 26 to 27] As shown in Table 3, hardened bodies were produced and evaluated in the same manner as in Example 2, except that the proportion of blast furnace slag and the proportion of fly ash were changed.

[0106] [Example 28] A hardened body was produced and evaluated in the same manner as in Example 2, except that the curing temperature was changed from 90°C to 60°C.

[0107] [Example 29] As shown in Table 3, the proportions of blast furnace slag, fly ash, sodium hydroxide (alkali activator (B)), alkali-resistant fiber (C), and sand (aggregate (E)) were changed; aluminum powder and hydrated lime were used instead of silica fume and sodium gluconate (other powder (F)); and after adding and mixing the alkali-resistant fiber (C) in the same manner as in Example 2, aluminum powder was further added and mixed. A hardened body was produced and evaluated in the same manner as in Example 2, except for these.

[0108] [Example 30] As shown in Table 3, the proportions of blast furnace slag, fly ash, sodium hydroxide as the alkali activator (B), alkali-resistant fiber (C), sand as the aggregate (E), and gypsum dihydrate were changed; aluminum powder and hydrated lime were used instead of silica fume and sodium gluconate; and aluminum powder was further added and mixed after the alkali-resistant fiber (C) was added and mixed in the same manner as in Example 19. A hardened body was produced and evaluated in the same manner as in Example 19.

[0109] [Example 31] As shown in Table 3, the proportions of blast furnace slag, fly ash, sodium hydroxide as the alkali activator (B), alkali-resistant fiber (C), sand as the aggregate (E), and gypsum dihydrate were changed; red mud was further used as the aluminosilicate source (A); aluminum powder and hydrated lime were used instead of silica fume and sodium gluconate; and after the alkali-resistant fiber (C) was added and mixed in the same way as in Example 19, aluminum powder was further added and mixed. A hardened body was produced and evaluated in the same manner as in Example 19.

[0110] [Example 32] As shown in Table 3, hardened bodies were produced and evaluated in the same manner as in Example 19, except that the proportion of blast furnace slag, the proportion of fly ash, the proportion of sodium hydroxide as the alkali activator (B), the proportion of alkali-resistant fiber (C), the proportion of sand as the aggregate (E), and the proportion of gypsum dihydrate were changed, red mud was further used as the aluminosilicate source (A), and slaked lime was used instead of silica fume and sodium gluconate.

[0111] [Comparative Example 1] As shown in Table 4, the content of sodium hydroxide, which is the alkali activator (B), was changed to a proportion greater than 10 mass% relative to the total solid content of the hardenable composition, and the proportions of blast furnace slag, fly ash, silica fume, and sand, which is the aggregate (E), were accordingly changed. Except for this, a hardened body was produced and evaluated in the same manner as in Example 2.

[0112] Comparative Example 2 As shown in Table 4, the content of blast furnace slag relative to the total solid content of the aluminosilicate source (A) was changed to less than 40 mass%, and accordingly, the proportion of fly ash and the proportion of sand as aggregate (E) were changed. Except for this, a hardened body was produced and evaluated in the same manner as in Example 2.

[0113] Comparative Example 3 The hardened body was produced and evaluated in the same manner as in Example 2, except that the alkali-resistant fiber (C) was not used, and the proportions of blast furnace slag, fly ash, and sand as aggregate (E) were changed as shown in Table 4, and drying was not performed.

[0114] Comparative Example 4 A hardened body was produced and evaluated in the same manner as in Example 1, except that the alkali-resistant fiber (C) was not used and the proportions of blast furnace slag, fly ash, and sand as aggregate (E) were changed as shown in Table 4.

[0115] Comparative Example 5 A hardened body was produced and evaluated in the same manner as in Example 2, except that the alkali-resistant fiber (C) was not used and the proportions of blast furnace slag, fly ash, and sand as aggregate (E) were changed as shown in Table 4.

[0116] Comparative Example 6 A cured product was produced and evaluated in the same manner as in Example 1, except that drying was not carried out.

[0117] Comparative Example 7 A cured product was produced and evaluated in the same manner as in Example 6, except that drying was not carried out.

[0118] [Comparative Example 8] A cured product was produced and evaluated in the same manner as in Example 7, except that drying was not carried out.

[0119] Comparative Example 9 A cured product was produced and evaluated in the same manner as in Example 8, except that drying was not carried out.

[0120] [Comparative Examples 10 to 11] Cured products were produced and evaluated in the same manner as in Example 1, except that the drying conditions were changed as shown in Table 4.

[0121] The properties of the fibers used in the Examples and Comparative Examples are shown in Table 1 below. The compositions in the Examples and Comparative Examples are shown in Tables 2 to 4. Table 5 shows the evaluation results of the cured products of the Examples and Comparative Examples. [Table 1]

[0122] [Table 2]

[0123] [Table 3]

[0124] [Table 4]

[0125] [Table 5]

[0126] The cured bodies produced in Examples 1 to 32 all had high flexural strength, high flexural toughness, and high dimensional stability. Furthermore, these cured bodies had smaller coefficients of variation for the average fiber content. This means that the average fiber content in the cured body varies less, and the smaller this variation, the more dimensional stability the cured body can have. As shown in the results of Example 4, the degree of fiber aggregation increased slightly as the fiber content in the cured body increased. However, because the cured body had the configuration of the present invention, a sufficiently small degree of fiber aggregation was obtained, allowing the cured body to achieve high flexural strength (MOR). As shown in the results of Examples 9 and 10, when water glass was used, superior bending strength and bending toughness were exhibited. When aluminum sulfate, which is a slag stimulant (D), was further added, even with a short curing time, further improved bending toughness was achieved, as shown in the results of Example 13. Furthermore, the compositions of Examples 14 to 16 were able to achieve not only further improved bending toughness but also further improved LOP. When water glass and aluminum sulfate were used, further improved LOP and bending toughness were obtained, as shown in the results of Examples 17-18. When gypsum dihydrate was used as the other powder (F), higher dimensional stability was obtained, as shown in the results of Examples 19 to 21. In addition, formability was improved, and it was found that cracking was better suppressed. Examples 29 to 32 are blends that also aim to reduce the weight of the cured product.

[0127] On the other hand, the cured body of Comparative Example 1, in which the content of sodium hydroxide as the alkaline activator (B) was more than 10 mass % relative to the total solid content of the curable composition, exhibited a high coefficient of variation of the average fiber content and a high rate of dimensional change. The hardened body of Comparative Example 2, in which the content of blast furnace slag relative to the total solid content of the aluminosilicate source (A) was less than 40 mass%, had a high coefficient of variation of the average fiber content and a high degree of fiber aggregation, and exhibited a low LOP, low bending toughness, and a high dimensional change rate compared to the corresponding Example 2. The cured body of Comparative Example 3, which did not contain reinforcing fibers and had a moisture content of more than 10.0 mass % relative to the total mass of the cured body, exhibited low bending strength (MOR) and significantly low bending toughness. The cured bodies of Comparative Examples 4 and 5, which did not contain reinforcing fibers, exhibited significantly low bending toughness. The hardened bodies of Comparative Examples 6 to 9, which had a moisture content of more than 10.0 mass % relative to the total mass of the hardened body, had significantly lower bending strength and bending toughness than the hardened bodies of the corresponding Examples (Examples 1, 6, 7 and 8). The hardened bodies of Comparative Examples 10 and 11, in which the moisture content of the hardened bodies was higher than 10.0 mass % relative to the total mass of the hardened bodies, had lower bending strength and bending toughness and a higher dimensional change rate than the hardened body of the corresponding Example (Example 1). [Industrial Applicability]

[0128] The cured product of the present invention has high bending strength and high dimensional stability, and therefore can be usefully used as a variety of civil engineering and construction materials, including, but not limited to, blocks, flooring, wall materials, ceiling materials, partitions, roofing materials, and roofing tiles.

Claims

1. A cured product of a curable composition comprising (A) an aluminosilicate source, (B) an alkali activator, and (C) an alkali-resistant fiber, the aluminosilicate source (A) contains blast furnace slag, and the content of the blast furnace slag is 40 mass% or more based on the total solid content of the aluminosilicate source (A); the content of the alkali activator (B) is 10 mass% or less based on the total solid content of the curable composition, A hardened body having a moisture content of 10.0 mass% or less based on the total mass of the hardened body.

2. The cured product according to claim 1 , wherein the content of the aluminosilicate source (A) is 20% by mass or more and 75% by mass or less based on the total solid content of the curable composition.

3. 3. The cured product according to claim 1, wherein the alkali-resistant fiber (C) is at least one selected from the group consisting of polyvinyl alcohol-based fiber, polyethylene fiber, polypropylene fiber, acrylic fiber, aramid fiber, and nylon fiber.

4. 4. The cured product according to claim 1, wherein the content of the alkali-resistant fiber (C) is 0.05 mass % or more and 5 mass % or less based on the total solid content of the cured product.

5. The cured product according to any one of claims 1 to 4, wherein the alkali-resistant fiber (C) has a fiber aggregation degree of 10% or less.

6. The hardened body according to any one of claims 1 to 5, wherein the coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces each weighing 10 g is cut out from the whole or a part of the hardened body is 30% or less.

7. The hardened body further contains an aggregate (E), and the content of the aggregate (E) is 15% by mass or more and 75% by mass or less based on the total solid content of the hardened body. The hardened body according to any one of claims 1 to 6.

8. The hardened body according to any one of claims 1 to 7, wherein the aluminosilicate source (A) further comprises at least one selected from the group consisting of fly ash, metakaolin, and red mud.

9. The hardened body further contains a slag stimulant (D), and the content of the slag stimulant (D) is 0.01 mass% or more and 3 mass% or less based on the total solid content of the hardened body. The hardened body according to any one of claims 1 to 8.

10. 10. The hardened body according to claim 1, further comprising a calcium sulfate derivative, the content of which is 0.01 mass % or more and 20 mass % or less based on the total solid content of the hardened body.

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