JP7143077B2 - Geopolymer molded body formed from curable composition - Google Patents

Description

The present invention relates to geopolymer compacts formed from curable compositions. The present invention also relates to a method for producing geopolymer moldings.

Conventional cementitious materials are used in a wide range of fields, especially in the field of civil engineering and construction, due to their versatility in manufacturing. However, the production of cement requires a very large amount of energy, and the accompanying large amount of carbon dioxide emissions poses a serious problem. Therefore, recently, a technique called geopolymer has been studied. Geopolymers are inorganic polymers produced by reacting aluminosilicates and alkali metal silicates. Compared to cementitious materials, geopolymers are superior in durability and acid resistance. Carbon dioxide emissions are remarkably low, so it is attracting attention as an environmentally friendly material.

For example, Patent Document 1 discloses that a geopolymer precursor obtained by mixing an aluminosilicate source and an alkali source is heated to a predetermined temperature or higher in advance in order to significantly delay the time to start setting and ensure a sufficient pot life. It describes a method for producing a hardened geopolymer that is heated to and held for a predetermined period of time, and describes that volcanic ash may be used as an aluminosilicate source.
Further, for example, in Patent Document 2, aluminum silicate, alkali metal silicate, reinforcing fibers and water are contained in order to improve the toughness of the cured molded product without impairing the fluidity of the curable composition. Curable compositions are described that contain predetermined amounts of specific slag particles in the curable composition.

JP 2012-240852 A JP 2011-184221 A

Various materials have been investigated as aluminosilicates to be used in the production of geopolymers, and representative materials include metakaolin and fly ash, but metakaolin is expensive, and fly ash is inexpensive, but reactive There was a problem of sexual instability. Moreover, the composition of industrial waste such as fly ash largely depends on the raw materials, and there is a problem that the quality is not stable when various raw materials are used.

Furthermore, the use of volcanic ash as described in Cited Document 1 is preferable from the viewpoint of effective utilization of volcanic ash, which is a natural pozzolanic substance, but there are various types of volcanic ash, such as metakaolin or fly ash. In comparison, the present inventors consider that it is difficult to obtain sufficient performance (e.g., reactivity in the curable composition and quality stability, strength, toughness, etc. in the molded article) in the curable composition and the molded article. was found by On the other hand, since geopolymers are very brittle, there is a known improvement plan to reinforce them with fibers as described in D2. Due to the difficulty of proper mixing, it has been difficult to sufficiently bring out the reinforcing effect of the fibers.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a geopolymer molded body formed from a curable composition having good reactivity, having stable quality, high strength and high toughness, and being environmentally friendly. .

In order to solve the above problems, the present inventors have made detailed studies on a geopolymer molded article formed from a curable composition, and have completed the present invention.

That is, the present invention includes the following preferred embodiments.
[1] A geopolymer compact formed from a curable composition containing (A) at least one aluminosilicate source, (B) at least one alkali metal silicate, and (C) alkali-resistant fibers, , the aluminosilicate source (A) has a _SiO2 content of 50% by mass or more based on the total mass of the aluminosilicate source (A), an amorphous proportion of 50% by mass or more, and an average particle size of is 50 μm or less, and contains an aluminosilicate source having an average particle size of 10 μm or less at 30% by mass or more based on the total mass of the aluminosilicate source (A).
[2] The compact according to [1] above, wherein the content of Al ₂ O ₃ in the aluminosilicate source (A) is 35% by mass or less based on the total mass of the aluminosilicate source (A).
[3] The formed article according to [1] or [2] above, which contains at least a volcanic ash-derived material as the aluminosilicate source (A).
[4] The molded article according to any one of [1] to [3] above, wherein the alkali-resistant fibers (C) have an average fiber diameter of 100 μm or less and an aspect ratio of 50 to 2,000.
[5] The molded article according to any one of [1] to [4], wherein the content of the alkali-resistant fiber (C) is 0.1 to 5 parts by mass with respect to 100 parts by weight of the molded article.
[6] The coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces weighing 20 g cut from the whole or a part of the molded body is 30% or less. [1] The molded article according to any one of [5].
[7] Any one of the above [1] to [6], wherein the alkali-resistant fiber (C) is at least one selected from the group consisting of polyvinyl alcohol fibers, polyethylene fibers, polypropylene fibers, acrylic fibers and aramid fibers. The molded article described in .
[8] mixing a component containing at least one aluminosilicate source (A) and at least one alkali metal silicate (B) with water;
A step of preparing a curable composition by adding alkali-resistant fibers (C) to the obtained mixture and further mixing, and obtaining a geopolymer molding by curing after molding the obtained curable composition. A method for producing a geopolymer molded body, comprising steps.

The geopolymer molded article of the present invention is formed from a curable composition having good reactivity, has stable quality, high strength and high toughness, and is environmentally friendly.

The molded bodies of the present invention are geopolymer moldings formed from a curable composition containing (A) at least one aluminosilicate source, (B) at least one alkali metal silicate, and (C) alkali-resistant fibers. a body, wherein the aluminosilicate source (A) has a _SiO2 content of 50% by mass or more based on the total mass of the aluminosilicate source (A) and an amorphous proportion of 50% by mass or more; , an aluminosilicate source having an average particle size of 50 μm or less and having an average particle size of 10 μm or less, in an amount of 30% by mass or more based on the total mass of the aluminosilicate source (A).

<(A) Aluminosilicate source>
The aluminosilicate source contains aluminosilicate (xM ₂ O.yAl ₂ O ₃ .zSiO ₂ .nH ₂ O, where M is an alkali metal) as a main component. Here, the main component means 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 alkali metal silicate (B)], cations such as aluminum and silicon are eluted, and these cations polycondense to form a strong SiO ₄ · A polymer network of AlO ₄ (geopolymer) is formed.

The aluminosilicate source (A) used in the present invention has a SiO ₂ (silicon dioxide) content of 50% by weight or more based on the total weight of the aluminosilicate source (A). Said SiO ₂ content is preferably at least 55% by weight, more preferably at least 60% by weight, particularly preferably at least 65% by weight, based on the total weight of the aluminosilicate source (A). When the SiO ₂ content is equal to or higher than the lower limit, higher strength and higher toughness are likely to be obtained in the produced geopolymer molding. The upper limit of the _SiO2 content is not particularly limited, and is usually 80% by mass.
The SiO ₂ content is measured, for example, by X-ray fluorescence analysis. The SiO ₂ content in the aluminosilicate source (A) is determined by selecting and using one or more of the substances described below as suitable examples of the aluminosilicate source (A), and/or using such substances By pulverizing and classifying and using a specific fraction, it is possible to adjust the lower limit or more.

The aluminosilicate source (A) used in the present invention also has an amorphous proportion of 50% by mass or more. If the amorphous ratio is less than 50% by mass, the reactivity of the aluminosilicate source (A) with the alkali metal silicate (B) is low. Desired quality stability, strength and toughness cannot be obtained. The amorphous ratio is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more. When the amorphous ratio is equal to or higher than the lower limit, cations such as aluminum and silicon are eluted from the aluminosilicate source by the alkali component of the alkali metal silicate (B), dissolved and easily reacted. Higher strength and higher toughness are likely to be obtained in the geopolymer compacts produced. The upper limit of the amorphous ratio is not particularly limited, and is usually 100% by mass.
The amorphous fraction is measured, for example, by X-ray diffraction analysis. For the amorphous ratio in the aluminosilicate source (A), one or more of the substances described later as suitable examples of the aluminosilicate source (A) are selected and used, and/or such substances are By pulverizing and classifying and using a specific fraction, it is possible to adjust the lower limit or more.

The aluminosilicate source (A) used in the present invention also has an average particle size of 50 μm or less, and 30% by mass or more, based on the total mass of the aluminosilicate source (A), has an average particle size of 10 μm or less. Contains certain aluminosilicate sources. The average particle size of the aluminosilicate source (A) is greater than 50 μm, or the aluminosilicate source (A) is less than 30% by weight based on the total mass of the aluminosilicate source (A). When the aluminosilicate source having a particle size of 10 μm or less is included, the produced geopolymer molding does not exhibit the desired properties due to the low reactivity of the aluminosilicate source (A) with the alkali metal silicate (B). Quality stability, strength and toughness cannot be obtained. The average particle size is preferably 30 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less. In addition, the content of the aluminosilicate source having an average particle size of 10 μm or less is preferably 50% by mass or more, more preferably 65% by mass or more, based on the total mass of the aluminosilicate source (A), especially Preferably, it is 80% by mass or more. When the average particle size is equal to or less than the upper limit and the content of the aluminosilicate source having an average particle size of 10 μm or less is equal to or more than the lower limit, the produced geopolymer molded body has higher strength and more High toughness is easily obtained. The lower limit of the average particle size is not particularly limited, and is usually 1 μm. The upper limit of the content of the aluminosilicate source having an average particle size of 10 μm or less is not particularly limited, and may be 100% by mass based on the total mass of the aluminosilicate source (A).
The average particle size is measured, for example, by a laser diffraction/scattering method. The average particle size of the aluminosilicate source (A) and the content of the aluminosilicate source having an average particle size of 10 μm or less are one or two of the substances described later as suitable examples of the aluminosilicate source (A). The above can be adjusted to desired values by using selected and/or grinding and classifying such materials and using specific fractions.

Suitable examples of the aluminosilicate source (A) include industrial wastes such as fly ash, red mud, silica fume and sewage sludge incineration ash; natural aluminosilicate minerals and calcined products thereof (e.g., metakaolin); and volcanic ash. mentioned. These substances are commercially available, and in the present invention, they may be used alone or in combination of two or more.

As described above, by pulverizing and classifying the above substances, it is possible to obtain the desired properties in the present invention, i.e., with a _SiO2 content of 50% by weight or more, based on the total weight of the aluminosilicate source (A). with an amorphous ratio of 50% by mass or more, an average particle size of 50 μm or less, and an average particle size of 10 μm or less, 30% by mass or more based on the total mass of the aluminosilicate source (A) An aluminosilicate source (A) can be prepared comprising an aluminosilicate source. Alternatively, from the above substances, a substance having the above-described predetermined properties in the present invention can be selected as the aluminosilicate source (A). Since the aluminosilicate source (A) having such properties exhibits good reactivity with the alkali metal silicate (B), a geopolymer compact produced using the aluminosilicate source (A) can combine stable quality with high strength and toughness.

As a method of pulverizing and classifying the above substances, for example, an air table is used as described in Journal of the Society of Materials Science, Japan, Vol.66, No.8, pp.574-581 (2017). Vibration is applied while an air current is passed from below, and in addition to the floating speed difference, the specific gravity separation action in the vibrating fluidized bed is used.

In one aspect of the present invention, the content of Al ₂ O ₃ in the aluminosilicate source (A) is preferably 35% by mass or less, more preferably 30% by mass, based on the total mass of the aluminosilicate source (A). % or less, particularly preferably 25 mass % or less. Since materials such as metakaolin, which generally have a relatively high Al ₂ O ₃ content (usually higher than 35% by weight), are expensive, the use of such materials as the aluminosilicate source (A) reduces production costs. Disadvantages are likely to occur. In this aspect of the invention, it is possible to use less expensive materials with relatively low Al ₂ O ₃ content (such as fly ash and volcanic ash) as the aluminosilicate source (A), while the aluminosilicate source ( As long as A) has the predetermined properties in the present invention, a geopolymer molded body having the same high strength and toughness as when metakaolin or the like is used as the aluminosilicate source (A) can be produced. Geopolymer compacts produced in this manner have advantages in terms of production costs due to the use of cheaper materials as the aluminosilicate source (A).

The aluminosilicate source (A) may contain volcanic ash from the viewpoints of easily obtaining the aluminosilicate source (A) having predetermined properties in the present invention, from the viewpoint of lower production costs, and from the viewpoint of quality stability. preferable. Therefore, in one aspect of the present invention, the shaped body preferably contains at least a material derived from volcanic ash as the aluminosilicate source (A). More preferably, the aluminosilicate source (A) consists of volcanic ash.

<(B) Alkali metal silicate>
The alkali metal silicate used in the present invention exhibits high alkalinity in water, and upon contact with the aluminosilicate source (A), activates it and has the effect of eluting cations such as Al and Si. . The alkali metal silicate also serves as a supply source of the silicic acid monomer [Si(OH) ₄ ] that forms the geopolymer.
Suitable examples of alkali metal silicates include sodium silicate, potassium silicate, lithium silicate, etc. 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. In addition, part of sodium silicate may be replaced with potassium silicate as long as the advantage of manufacturing cost is not impaired. 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.

Alkali metal silicates are usually used in the form of aqueous solutions. The molar ratio of alkali metal/water in the aqueous alkali metal silicate solution is preferably 0.04 or more. The higher the molar ratio, the higher the strength of the resulting geopolymer molded body, so the higher the molar ratio, the better. The fluidity of the curable composition containing the fibers (C) is lowered, making molding difficult. Therefore, the molar ratio is preferably 0.06 to 0.25, more preferably 0.08 to 0.22, particularly preferably 0.12 to 0.2.

The content of the alkali metal silicate is preferably 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, particularly preferably 15 to 60 parts by mass, as a solid content with respect to 100 parts by mass of the aluminosilicate source (A). part by mass. When the content of the alkali metal silicate is within the above range, higher strength and higher toughness are likely to be obtained in the produced geopolymer compact.

<(C) Alkali-resistant fiber>
The alkali-resistant fibers used in the present invention have the effect of increasing the strength and toughness of geopolymer moldings.

The alkali-resistant fiber is not particularly limited, whether it is an organic fiber or an inorganic fiber, as long as it has chemical durability against alkali. Examples of alkali-resistant inorganic fibers include alkali-resistant glass fibers, steel fibers, stainless fibers, and carbon fibers. Examples of alkali-resistant organic fibers include polyvinyl alcohol (hereinafter sometimes referred to as PVA) fibers, polyolefin fibers (for example, polyethylene fibers and polypropylene fibers), ultra-high molecular weight polyethylene fibers, polyamide fibers (polyamide 6 , polyamide 6,6, and polyamide 6,10, etc.), aramid fiber (especially para-aramid fiber), polyparaphenylenebenzobisoxazole fiber [e.g. polyparaphenylenebenzobisoxazole (PBO) fiber], acrylic fiber, rayon fiber ( Examples include polynosic fibers and solvent-spun cellulose fibers), polyphenylene sulfide fibers (PPS fibers), and various alkali-resistant fibers such as polyetheretherketone fibers (PEEK fibers). These alkali-resistant fibers may be used alone or in combination of two or more.

Among these, polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, and aramid fibers are preferably used from the viewpoint of easily imparting excellent reinforcing properties to geopolymer moldings and being able to be produced at low cost. Therefore, in one aspect of the present invention, the alkali-resistant fiber is preferably at least one selected from the group consisting of polyvinyl alcohol fibers, polyethylene fibers, polypropylene fibers, acrylic fibers and aramid fibers.

The average fiber diameter of the alkali-resistant fibers is preferably 100 µm or less, more preferably 80 µm or less, and particularly preferably 60 µm or less. The average fiber diameter of the alkali-resistant fibers is usually 3 µm or more, more preferably 5 µm or more, and particularly preferably 7 µm or more. When the average fiber diameter of the alkali-resistant fibers is equal to or less than the above upper limit, such alkali-resistant fibers have sufficient fiber strength and are easy to stably produce industrially. When the average fiber diameter of the alkali-resistant fibers is at least the lower limit, the fibers are more uniformly dispersed in the geopolymer matrix. Here, in the present invention, the term "geopolymer matrix" (hereinafter sometimes referred to as "matrix") means a geopolymer portion that binds alkali-resistant fibers in a geopolymer molding.

The aspect ratio of the alkali-resistant fiber is preferably 50 to 2000 from the viewpoint of easily achieving both good dispersibility of the fiber in the curable composition and good reinforcing property after curing of the curable composition. It is preferably 50 to 450, more preferably. Here, in the present invention, the aspect ratio means the ratio (L/D) of fiber length (L) to fiber diameter (D).

The average fiber diameter and aspect ratio of the alkali-resistant fibers are determined according to JIS L 1015 "Chemical fiber staple test method (8.5.1)".

The average fiber strength of the alkali-resistant fiber of the present invention is preferably 3 cN/dtex or more, more preferably 4 cN/dtex or more, and particularly preferably 5 cN/dtex or more. When the average fiber strength of the alkali-resistant fibers is equal to or higher than the above lower limit, it is easier to enhance the reinforcing performance of the geopolymer molded article. The upper limit of the average fiber strength of the alkali-resistant organic fiber of the present invention is appropriately set according to the type of fiber, and is, for example, 30 cN/dtex or less. Incidentally, the average fiber strength is determined according to JIS L 1015 "Chemical fiber staple test method (8.5.1)".

When PVA-based fibers such as vinylon fibers are used as alkali-resistant fibers, PVA-based fibers having the following properties may be used. The degree of polymerization of the PVA-based polymer that constitutes the PVA-based fiber can be appropriately selected depending on the purpose, and is not particularly limited. Considering the mechanical properties of the resulting fiber, the average degree of polymerization of the PVA-based polymer obtained from the viscosity of the aqueous solution at 30°C is preferably about 500 to 20000, more preferably about 800 to 15000, and particularly preferably 1000 to 1000. It is about 10000. Among them, the average degree of polymerization of the PVA-based polymer is preferably 1000 or more, more preferably 1200 or more, more preferably 1500 or more, and particularly preferably 1750 or more, from the viewpoint of the strength of the obtained fiber. The PVA-based polymer may be a medium polymerization product with an average polymerization degree of 1000 or more and less than 3000, or a high polymerization degree product with an average polymerization degree of 3000 or more.

The degree of saponification of the PVA-based polymer can also be appropriately selected depending on the purpose and is not particularly limited. The degree of saponification of the PVA-based polymer may be, for example, 95 mol % or more, preferably 98 mol % or more, from the viewpoint of the mechanical properties of the obtained fiber. The degree of saponification of the PVA-based polymer may be 99 mol% or more, or 99.8 mol% or more. When the degree of saponification of the PVA-based polymer is at least the above lower limit, the obtained fiber tends to have good mechanical properties, processability, manufacturing cost, and the like.

The PVA-based fiber used in the present invention is produced by dissolving such a PVA-based polymer in a solvent, spinning it by any one of wet, dry-wet, or dry methods, followed by hot drawing. Wet spinning is a method in which a spinning dope is discharged directly from a spinning nozzle into a solidifying bath. Dry-wet spinning is a method in which a spinning stock solution is once discharged from a spinning nozzle into air or an inert gas at an arbitrary distance, and then introduced into a solidification bath. Dry spinning is a method of extruding a spinning dope into air or an inert gas. After spinning, the PVA-based fiber may be subjected to a drawing treatment, if necessary. In addition, acetalization treatment or the like, which is generally performed for PVA-based fibers, may be performed.

The solvent used in the spinning dope for the PVA-based fiber is not particularly limited as long as it is capable of dissolving PVA. For example, water, dimethylsulfoxide (DMSO), dimethylformamide, dimethylacetamide, and polyhydric alcohols (eg, glycerin, ethylene glycol, triethylene glycol, etc.) may be used singly or in combination of two or more. In the present invention, when wet spinning is performed, it is preferable to use water or an organic solvent as the solvent. Among these, water and DMSO are particularly preferred from the viewpoint of ease of supply and impact on the environment. The concentration of the polymer in the spinning dope varies depending on the composition and degree of polymerization of the PVA-based polymer and the type of solvent, but is generally 6-60% by mass.

Dry spinning may also use the above solvents. In that case, either water or an organic solvent may be used.

In addition to the PVA-based polymer, the spinning dope may contain additives and the like depending on the purpose, as long as they do not impair the effects of the present invention. Additives include, for example, boric acid, surfactants, antioxidants, decomposition inhibitors, antifreeze agents, pH adjusters, masking agents, coloring agents and oils.

The solvent used in the solidification bath may be appropriately selected according to the type of solvent used in the spinning dope. When the spinning dope is an aqueous solution, the solidifying bath may be an aqueous solution of an inorganic salt (for example, sodium sulfate, ammonium sulfate, sodium carbonate, sodium hydroxide, etc.) capable of solidifying the PVA-based polymer, or an alkaline aqueous solution. When the spinning stock solution is an organic solvent solution, the solidifying bath includes, for example, alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, which have the ability to solidify the PVA-based polymer. may be used.

In the present invention, PVA-based fibers obtained by dry spinning, or PVA-based fibers obtained by wet spinning from a spinning stock solution using water or an organic solvent as a solvent are preferable from the viewpoint of fiber strength.

In order to extract and remove the solvent of the spinning stock solution from the solidified raw yarn, the raw yarn may be passed through an extraction bath, and the raw yarn may be wet-drawn simultaneously with the extraction. After wet drawing, the fiber may be dried and, if necessary, further subjected to dry heat drawing. When stretching is carried out, the total stretching ratio (product of wet stretching and stretching ratio after drying) may be, for example, 5 to 25 times, preferably about 8 to 20 times.

As alkali-resistant fibers, commercially available fibers may be used, examples of which include organic fibers such as Kuraray Co., Ltd.'s vinylon fiber trade name "Kuraron" and Toray Industries, Inc. nylon fiber trade name "Tough Binder", and Inorganic fibers such as "ARG Fiber 25 mm" (trade name) manufactured by Nippon Electric Glass Co., Ltd. and "Anti-Crack HD" (trade name) manufactured by Taiheiyo Materials Co., Ltd. can be used.

The content of the alkali-resistant fiber is preferably 0.3 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and particularly preferably 0.7 to 10 parts by mass, based on 100 parts by mass of the aluminosilicate source (A). part by mass. When the content of the alkali-resistant fiber is within the above range, higher strength and higher toughness are likely to be obtained in the produced geopolymer molded article.

In one aspect of the present invention, the content of the alkali-resistant fiber (C) is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, and particularly It is preferably 0.3 to 3 parts by mass. When the content of the alkali-resistant fiber is within the above range, higher strength and higher toughness are likely to be obtained in the produced geopolymer molded article. The content of the alkali-resistant fiber (C) in the geopolymer molded body is determined by the method described in Examples below.

In one aspect of the present invention, the coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces of 20 g cut from the whole or part of the geopolymer molded body is preferably is 30% or less, more preferably 25% or less, and particularly preferably 20% or less. The smaller the variation coefficient of the average content of the alkali-resistant fibers (C), the more uniformly the alkali-resistant fibers (C) contained in the geopolymer molded body are dispersed. The body tends to have more stable quality, higher strength and higher toughness. The coefficient of variation is obtained by the method described in Examples below.

<Optional component>
In addition to the aluminosilicate source (A), the alkali metal silicate (B) and the alkali-resistant fiber (C), the curable composition in the present invention contains an aggregate, an alkali metal silicate ( It may further contain one or more components selected from the group consisting of an alkali metal source different from B) and an admixture. The addition of aggregates and admixtures can increase the strength and toughness of geopolymer compacts.

Aggregates generally used for concrete and mortar may be used as aggregates. The aggregate is different from the aluminosilicate source (A) previously described. Aggregates are classified into fine aggregates and coarse aggregates according to particle size, natural aggregates and artificial aggregates according to their origin, and light aggregates, ordinary aggregates and heavy aggregates according to densities. These aggregates may be used alone or in combination of two or more.

The fine aggregate may be an aggregate having a particle size of 5 mm or less, for example, sand having a particle size of 5 mm or less; inorganic materials such as silica stone, slag, slag particles, blast furnace slag, volcanic ash, various types of sludge, and rock minerals. powdered or granulated fine aggregate. Examples of sand 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.

Coarse aggregate is aggregate containing 85% by mass or more of particles having a particle size of 5 mm or more based on the total amount of coarse aggregate. The coarse aggregate may consist of particles with a particle size greater than 5 mm. Examples of coarse aggregate include various types of gravel, artificial aggregate (such as blast furnace slag), and recycled aggregate (such as recycled aggregate from construction waste). You may use these coarse aggregates individually or in combination of 2 or more types, respectively.

Blast furnace slag includes crystalline slow-cooled slag and amorphous granulated slag. Since water granulated slag has latent hydraulic properties and brings about strength improvement or curing acceleration of the geopolymer compact, it is preferably used in addition to the essential components (A) to (C). A preferred form of the granulated blast furnace slag is one having an amorphous ratio of 90% by mass or more and an average particle size similar to that of the aluminosilicate source (A). Since blast furnace slag contains silicon dioxide (SiO ₂ ) and alumina, it can also be a source of silicic _acid monomers and aluminum ions involved in the polycondensation reaction. Since it is less than 50% by mass, it does not correspond to the aluminosilicate source (A) in the present invention.

Lightweight aggregates include, for example, natural lightweight aggregates such as volcanic gravel, expanded slag and coal shells, and artificial lightweight aggregates such as expanded perlite, expanded perlite, expanded obsidian, vermiculite, shirasu balloons and fly ash microballoons. material. These lightweight aggregates may be used alone or in combination of two or more.

Moreover, the curable composition in the present invention may further contain functional aggregates in addition to the above aggregates. Here, the functional aggregates include colored aggregates, hard aggregates, elastic aggregates, and aggregates having a specific shape. Specifically, layered silicates (for example, , mica, talc and kaolin), alumina and silica, and the like. The ratio of the functional aggregate to the aggregate can be appropriately set according to each type. For example, the mass ratio of the aggregate and the functional aggregate (aggregate/functional aggregate) is It may be from 99/1 to 70/30, preferably from 98/2 to 75/25, more preferably from 97/3 to 80/20. These functional aggregates may be used alone or in combination of two or more.

When the curable composition in the present invention contains an aggregate, the content thereof is preferably 30 to 500 parts by mass, more preferably 50 to 400 parts by mass, based on 100 parts by mass of the aluminosilicate source (A). Particularly preferably, it is 80 to 300 parts by mass. When the content of the aggregate is within the above range, the manufactured geopolymer molded body tends to have higher strength and higher toughness.

Alkali metal sources different from the alkali metal silicate (B) include, for example, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate. These may be used alone or in combination of two or more. Since this alkali metal source exhibits high alkalinity in water, similar to the alkali metal silicate (B), when it comes into contact with the aluminosilicate source (A), it activates it and cations such as Al and Si has the effect of eluting. Therefore, when this alkali metal source is added to the curable composition, it has the effect of supplementing the activation of the aluminosilicate source (A) by the alkali metal silicate (B).

When the curable composition in the present invention contains an alkali metal source different from the alkali metal silicate (B), the content thereof is preferably 3 parts per 100 parts by mass of the aluminosilicate source (A). to 30 parts by mass, more preferably 5 to 25 parts by mass, particularly preferably 7 to 20 parts by mass. When the content of the alkali metal source is within the above range, the activation of the aluminosilicate source (A) is facilitated, so that the produced geopolymer molded body has higher strength and higher toughness. easy to get

<Method for producing a geopolymer molded body>
The geopolymer molding of the present invention is, for example,
mixing ingredients comprising at least one aluminosilicate source (A) and at least one alkali metal silicate (B) with water;
A step of preparing a curable composition by adding alkali-resistant fibers (C) to the obtained mixture and further mixing, and obtaining a geopolymer molding by curing after molding the obtained curable composition. It is manufactured by a method including steps.

As the aluminosilicate source (A), alkali metal silicate (B) and alkali-resistant fiber (C) used in this production method, <(A) aluminosilicate source> and <(B) alkali Metal silicate> and <(C) Alkali-resistant fiber> can be used, respectively. In addition, in this manufacturing method, the ingredients described in the previous <Optional Ingredients> paragraph can be used.

The mixing method in the first mixing step is not particularly limited. mixers, pan mixers, planetary mixers, Eirich mixers, etc.). If any of the previously described optional ingredients (eg, aggregates and alkali metal sources different from alkali metal silicate (B), etc.) are added, they can be added during this mixing step. There are no particular restrictions on the order in which each component is added to the mixer or the like. The amount of water is also not particularly limited, but from the viewpoint that the curable composition does not contain excessive water and a homogeneous mixture is easily obtained, it is usually 30 to 300 parts by mass. Water may be added independently or in the form of water as its solvent when water glass is used as the alkali metal silicate (B). water-soluble substances [e.g. alkali metal silicate (B) and, if added, water-soluble optional ingredients [e.g. alkali metal sources different from alkali metal silicate (B), e.g. sodium hydroxide] ] is dissolved in water in advance to form an aqueous solution, and the resulting aqueous solution and water-insoluble components [e.g., aluminosilicate source (A), water-insoluble optional components when added (e.g., blast furnace slag, sand, etc. aggregate)] may be mixed. At that time, the aqueous solution may be mixed with a mixture obtained by separately mixing the water-insoluble components. Moreover, the mixing time is not particularly limited, and the mixing may be performed until a homogeneous mixture is obtained.

Next, the alkali-resistant fiber (C) is added to the resulting mixture and further mixed. A predetermined amount of the alkali-resistant fiber (C) may be added at once, or may be added in two or more portions. As a method of adding the alkali-resistant fibers (C), it is preferable to add the fibers in a state of being aligned and converged in one direction from the viewpoint of easily obtaining a homogeneous curable composition. The mixing time after adding the fibers is not particularly limited, and the mixing may be continued until a homogeneous curable composition is obtained.

Subsequently, after molding the obtained curable composition, the curable composition is cured so that it can withstand manufacturing steps such as demolding or transfer. In the production method of the present invention, the curable composition obtained is obtained by a so-called casting method in which the curable composition is poured into an open mold, or a dehydration molding method in which the curable composition is pressed or sucked and dewatered. Alternatively, known techniques such as an injection molding method in which a slurry is injected into a closed mold and an extrusion molding method in which a product having a given shape can be molded through a die can be used. At this time, if necessary, pressure or vibration may be applied. Alternatively, the curable composition may be pressed by a press using a top molding die, rolls, or the like. Curing may generally be carried out at normal pressure or under pressure at a temperature of 20-95° C., eg room temperature (25° C.) or 90° C., at a relative humidity of 20-99%. Curing time is appropriately set according to the pressure, temperature and/or humidity at which curing is performed. Higher pressure, temperature and humidity can shorten the curing time, and lower pressure, temperature and humidity can increase the curing time. For example, when normal pressure steam curing (wet curing) is performed at a temperature of 80° C. and a humidity of 90% or more, curing may be performed for about 4 to 24 hours. Curing cures the curable composition. Additional curing may then be performed, in which case the curing conditions for the additional curing may be the same as for the initial curing or may be different.

Because the resulting geopolymer compact is formed from a curable composition that has good reactivity due to the inclusion of a specific aluminosilicate source, alkali metal silicate and alkali-resistant fibers, and Since the components of the curable composition (especially the alkali-resistant fiber) are more uniformly mixed by the production by the above method, it is possible to have both stable quality, high strength and high toughness.

EXAMPLES 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.

<Measurement method and evaluation method>
Various measurement methods and evaluation methods in Examples and Comparative Examples are as follows.

[ _SiO2 content and amorphous fraction in the aluminosilicate source]
The SiO ₂ content was obtained by quantifying the Si content with a fluorescent X-ray measuring device (RIX3100 manufactured by Rigaku Corporation) and converting it to oxide.
Moreover, the amorphous ratio was calculated by the following method.
(i) Using an X-ray diffractometer (SmartLab manufactured by Rigaku Corporation), the abundance ratio of all crystals contained in the aluminosilicate source was quantified by Rietveld analysis.
(ii) The aluminosilicate source was put into a muffle furnace (FO310 manufactured by Yamato Kagaku Co., Ltd.) set at 1000° C., and the ignition loss was determined from the change in mass before and after the introduction.
(iii) Amorphous ratio was calculated by the following formula.

[Average Particle Size of Aluminosilicate Source and Ratio of Aluminosilicate Source with Average Particle Size of 10 μm or Less]
The average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 μm or less are obtained from the particle size distribution obtained using a dynamic light scattering photometer DLS-7000 manufactured by Otsuka Electronics Co., Ltd. rice field.

[Content of Al ₂ O ₃ in aluminosilicate source]
The Al ₂ O ₃ content was obtained by quantifying the Al content using a fluorescent X-ray measuring device (RIX3100 manufactured by Rigaku Corporation) and converting it to oxide.

[Average fiber diameter and aspect ratio of alkali-resistant fiber (C)]
Regarding the average fiber diameter, 20 fibers were randomly selected, the fiber diameter at the central portion in the length direction of each fiber was measured with an optical microscope, and the average value was taken as the average fiber diameter. The average fiber length was calculated according to JIS L 1015 "Chemical fiber staple test method (8.5.1)", and the aspect ratio of the fiber was obtained from the ratio to the average fiber diameter.

次いで、残り１０個の切出片〔Ｗ_１～Ｗ_１０（ｇ）の重量を有する切出片〕を６００℃のマッフル炉に３０分間投入して、切出片に含まれる耐アルカリ性繊維（Ｃ）を燃焼させた後、冷却して各々の重量〔Ｗ_１－１～Ｗ_１０－１（ｇ）〕を測定した。
Ｗ_１（ｇ）の重量を有する切出片における耐アルカリ性繊維（Ｃ）の含有率を、下記式により算出した。

Ｗ_２～Ｗ_１０（ｇ）の重量を有する切出片の各々についても同様に、耐アルカリ性繊維（Ｃ）の含有率を算出した。
更に、Ｗ_１～Ｗ_１０（ｇ）の重量を有する切出片の耐アルカリ性繊維（Ｃ）の含有率の標準偏差と平均値とを算出し、下記式により、耐アルカリ性繊維（Ｃ）の平均含有率の変動係数を算出した。

また、上記方法により求めた、Ｗ_１～Ｗ_１０（ｇ）の重量を有する切出片の各々における耐アルカリ性繊維（Ｃ）の含有率から、各切出片１００質量部に対する耐アルカリ性繊維（Ｃ）の部数を算出し、その平均値を求めて、成形体１００質量部に対する耐アルカリ性繊維（Ｃ）の部数とした。 [Content of alkali-resistant fiber (C) and coefficient of variation of average content]
Pieces of 20 g were cut out from the compact, 11 of the cut pieces were arbitrarily selected, dried at 105° C. for 3 hours, and the weight of each cut piece [W ₁ to W ₁₁ (g )] was measured.
One of the 11 cut pieces was ground in a mortar. Here, it is assumed that a piece having a weight of W ₁₁ (g) is pulverized. After pulverization, water was added to the pulverized material and the mixture was filtered through a 10-mesh wire mesh to separate the alkali-resistant fiber (C) from the matrix. Next, the filtrate was filtered with filter paper to recover the matrix, dried at 105° C. for 3 hours, and then weighed accurately for the weight W _11-1 (g) of the matrix. After that, it was placed in a muffle furnace at 600° C. for 30 minutes, cooled, and the weight W _11-2 (g) of the matrix was measured, and the weight reduction rate X (%) of the matrix was calculated by the following formula.

Next, the remaining 10 cut pieces [cut pieces having a weight of W ₁ to W ₁₀ (g)] were placed in a muffle furnace at 600 ° C. for 30 minutes, and the alkali-resistant fibers (C ) were burned, cooled, and their weights [W _1-1 to W _10-1 (g)] were measured.
The content of the alkali-resistant fiber (C) in the piece having a weight of W ₁ (g) was calculated by the following formula.

The content of the alkali-resistant fiber (C) was similarly calculated for each piece having a weight of W ₂ to W ₁₀ (g).
Furthermore, the standard deviation and the average value of the content of the alkali-resistant fiber (C) of the cut piece having a weight of W ₁ to W ₁₀ (g) are calculated, and the average of the alkali-resistant fiber (C) is calculated by the following formula. The coefficient of variation of the content was calculated.

Also, from the content of the alkali-resistant fiber (C) in each piece having a weight of W ₁ to W ₁₀ (g) obtained by the above method, the alkali-resistant fiber (C ) was calculated, and the average value was obtained as the number of parts of the alkali-resistant fiber (C) per 100 parts by mass of the molded article.

[Bending strength, bending toughness, and coefficient of variation of bending strength of compact]
A bending test was carried out in accordance with JIS A 1106:2006 using a trisecting point loading method with n=6 to determine the bending strength and bending toughness of the compact. Also, the coefficient of variation of bending strength was calculated by the following formula.

Example 1
A curable composition was prepared in the amount shown in Table 2 using the materials shown in Tables 1 and 2, which will be described later, and a geopolymer molding was produced from the resulting curable composition.
Specifically, first, in the amounts shown in Table 2, No. 1 water glass (concentration: about 55% by mass) and sodium hydroxide were dissolved in water to prepare geopolymer water. Next, the aluminosilicate source, granulated blast furnace slag, and sand in the amounts shown in Table 2 were added to the mortar mixer and mixed for 1 minute, and then the geopolymer water was added to the mortar mixer and mixed for 3 minutes. . Subsequently, the unidirectionally aligned and converged fibers in the amount shown in Table 2 were put into a mortar mixer and further mixed for 1 minute to prepare a curable composition. The obtained curable composition is poured into a mold having a width of 6 cm, a length of 24 cm, and a thickness of 1 cm, and the mixture is cured for 8 hours under normal pressure at 80°C and RH 90%, and then removed from the mold. A geopolymer molding was produced by
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 2
A geopolymer compact was produced in the same manner as in Example 1, except that the average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 µm or less were changed as shown in Table 2. .
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 3
A geopolymer molded body was produced in the same manner as in Example 2, except that the fiber ratio was changed as shown in Table 2.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 4
A geopolymer molded body was produced in the same manner as in Example 1, except that the amorphous ratio of the aluminosilicate source was changed as shown in Table 2.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 5
A geopolymer compact was produced in the same manner as in Example 1, except that the average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 µm or less were changed as shown in Table 2. .
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 6
A geopolymer molded body was produced in the same manner as in Example 2, except that the type of fiber was changed as shown in Table 2.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 7
A geopolymer molded body was produced in the same manner as in Example 1, except that the type of fiber was changed as shown in Table 2.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Example 8
A geopolymer compact was produced in the same manner as in Example 1, except that the average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 µm or less were changed as shown in Table 2. .
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Comparative example 5
A geopolymer molding was produced in the same manner as in Example 1, except that fly ash type II was used instead of Kagoshima volcanic ash.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Comparative example 1
A geopolymer molded body was produced in the same manner as in Example 1, except that the alkali-resistant fiber was not added and the amount of geopolymer water was changed as shown in Table 2.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Comparative example 2
A geopolymer compact was produced in the same manner as in Example 1, except that the average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 µm or less were changed as shown in Table 2. .
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Comparative example 3
A geopolymer was prepared in the same manner as in Example 1 except that the amorphous ratio of the aluminosilicate source, the average particle size, and the ratio of the aluminosilicate source having an average particle size of 10 μm or less were changed as shown in Table 2. A molded body was produced.
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

Comparative example 4
A geopolymer compact was produced in the same manner as in Example 1, except that the average particle size of the aluminosilicate source and the ratio of the aluminosilicate source having an average particle size of 10 µm or less were changed as shown in Table 2. .
The resulting geopolymer moldings were evaluated as previously described. Table 2 shows the results.

As shown in Table 2, geopolymer compacts of the present invention formed from curable compositions containing specific aluminosilicate sources, alkali metal silicates, and alkali-resistant fibers exhibit high flexural strength and bending strength. It had toughness, ie high strength and high toughness. The geopolymer compacts of the present invention also had smaller coefficients of variation for average fiber content and coefficients of variation for flexural strength. This means that the variation in the average content of fibers and the variation in bending strength are small, indicating that a geopolymer molded article of stable quality was obtained.

On the other hand, a geopolymer compact formed from a curable composition that does not contain alkali-resistant fibers (Comparative Example 1) has a lower flexural strength and significantly lower flexural toughness, indicating that the specific aluminosilicate source of the present invention is Geopolymer compacts formed from the free curable composition (Comparative Examples 2-4) had lower bending strength and lower bending toughness. That is, these geopolymer compacts did not have sufficient strength and toughness. In addition, the geopolymer moldings of Comparative Examples 2 to 4 had a large variation coefficient of the average fiber content and a large variation coefficient of the bending strength, that is, the variation of the average fiber content and the variation of the bending strength. The quality stability of such geopolymer moldings is insufficient.

The geopolymer compact of the present invention is stable because it is formed from a curable composition that has good reactivity due to the inclusion of a specific aluminosilicate source, alkali metal silicate and alkali-resistant fibers. It can have both high strength and high toughness, and is environmentally friendly. Therefore, the geopolymer molded article of the present invention is not particularly limited, but is useful as various civil engineering and construction materials such as blocks, flooring materials, wall materials, ceiling materials, partitions, roofing materials, and tiles. can be used for

Claims (7)

A geopolymer compact formed from a curable composition comprising (A) at least one aluminosilicate source, (B) at least one alkali metal silicate and (C) alkali-resistant fibers, wherein the aluminosilicate The salt source (A) has a SiO ₂ content of 65 to 80 % by mass based on the total mass of the aluminosilicate source (A), an amorphous proportion of 50% by mass or more, and an average particle size of 50 μm. 20 g from the whole or a part of the molded body containing an aluminosilicate source having an average particle size of 10 μm or less in an amount of 30% by mass or more based on the total mass of the aluminosilicate source (A) The molded body, wherein the coefficient of variation of the average content of the alkali-resistant fiber (C) contained in 10 pieces cut out in the above manner is 25% or less. The compact according to claim ₁ , wherein the content of _Al2O3 in the aluminosilicate source (A) is 35% by mass or less based on the total mass of the aluminosilicate source (A). 3. The molded article according to claim 1, which contains at least a volcanic ash-derived material as the aluminosilicate source (A). The molded article according to any one of claims 1 to 3, wherein the alkali-resistant fibers (C) have an average fiber diameter of 100 µm or less and an aspect ratio of 50 to 2,000. The molded article according to any one of claims 1 to 4, wherein the content of the alkali-resistant fiber (C) is 0.1 to 5 parts by mass with respect to 100 parts by weight of the molded article. The molded article according to any one of claims 1 to 5, wherein the alkali-resistant fiber (C) is at least one selected from the group consisting of polyvinyl alcohol fiber, polyethylene fiber, polypropylene fiber, acrylic fiber and aramid fiber. mixing ingredients comprising at least one aluminosilicate source (A) and at least one alkali metal silicate (B) with water;
A step of preparing a curable composition by adding alkali-resistant fibers (C) aligned and converged in one direction to the obtained mixture and further mixing to prepare a curable composition, and molding the obtained curable composition. A method for producing a geopolymer molded body, comprising the step of obtaining a geopolymer molded body by subsequent curing,
The method, wherein the SiO ₂ content of the aluminosilicate source (A) is 65-80% by weight based on the total weight of the aluminosilicate source (A) .