Geopolymer composition, geopolymer cured body, and method for producing geopolymer cured body

Abstract

This geopolymer composition comprises an active filler, an aggregate, an activator, water, and a dispersant. The active filler contains coal ash. The dispersant is a polycondensate-based dispersant containing a polyalkylene glycol monophenyl ether as a partial structure. The amount of solid content blended is 0.1%-1.5% by mass with respect to the total mass of the composition. In the geopolymer composition, Z calculated by formula α: Z = X × Y / (w / b) (in formula α, X represents the average Blaine's value (cm2 / g) of coal ash, Y represents the amount (mass%) of coal ash blended, w / b represents the percentage of (amount (mass%) of water blended) / (total amount (mass%) of active filler blended), and w / b is 55.0 or less) is 3300 or less.

Description

Geopolymer composition, hardened geopolymer body, and method for producing hardened geopolymer body

[0001] The present invention relates to a geopolymer composition, a hardened geopolymer, and a method for producing the hardened geopolymer.

[0002] Hardened materials such as concrete, mortar, artificial stone, and hardened building materials generally contain cement. However, cement releases a large amount of CO when fired. ２ Therefore, methods for producing hardened materials such as concrete and mortar that do not use cement and are environmentally friendly are attracting attention. In particular, methods for producing hardened materials using the geopolymer method are being actively researched.

[0003] In the geopolymer method, powders containing silicon and aluminum as primary components are used as binders to bond the powders together to produce artificial rocks. The hardened geopolymer formed by the geopolymer method is produced by inducing a geopolymer reaction using an activated filler as an aluminosilicate source and an alkaline aqueous solution as an activator. Examples of activated fillers that can be used include natural products such as coal ash, kaolin, and clay, as well as silica fume, blast furnace slag, and rice husk ash. Examples of alkaline aqueous solutions that can be used include aqueous solutions of sodium hydroxide, water glass (sodium silicate), and the like.

[0004] On the other hand, when hardened geopolymer compositions that have been studied and reported to date are used in practical applications as replacements for cement-based concrete, mortar, and other hardened products, there is a problem that their hardening speed is too fast. Specifically, their fluidity drops significantly and they begin to set about one hour after mixing. If the hardening speed is too fast, the geopolymer composition becomes difficult to handle at the manufacturing site of hardened products such as mortar and concrete.

[0005] Patent Document 1 describes a method for producing a hardened geopolymer to address the problem of the hardening speed of such geopolymer compositions. Specifically, Patent Document 1 describes a method for producing a hardened geopolymer, which involves preparing a geopolymer composition containing (A) component: fly ash, (B) component: ground granulated blast furnace slag, (C) component: an alkaline solution containing water glass, (D) component: aggregate, (E) component: orthophosphate, and water, and hardening the geopolymer composition. The method for producing a hardened geopolymer described in Patent Document 1 also describes that the fluidity retention time can be sufficiently extended by adding (E) component: orthophosphate to the composition.

[0006] [Patent Document 1] JP 2020-26357 A

[0007] The present invention aims to provide a geopolymer composition that can maintain good fluidity for a long period of time using a low-cost and simple method, even when coal ash of various qualities is used as a raw material.

[0008] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.

[0009] That is, the geopolymer composition according to the first aspect of the present invention is a geopolymer composition comprising an active filler, an aggregate, an activator, water, and a dispersant, wherein the active filler comprises coal ash, and the dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure, and the amount of solid content is 0.1 mass% or more and 1.5 mass% or less with respect to the total mass of the geopolymer composition, and in the geopolymer composition, the formula α: Z = X × Y / (w / b) (in formula α, X is the average Blaine value (cm ２ / g), Y represents the blending amount (mass%) of the coal ash, w / b represents the percentage of (the blending amount (mass%) of the water) / (the blending amount (mass%) of the total active filler), and w / b is 55.0 or less), and Z calculated from this is 3,300 or less.

[0010] A hardened geopolymer according to a second aspect of the present invention is obtained by hardening the geopolymer composition according to the first aspect.

[0011] A method for producing a hardened geopolymer according to a third aspect of the present invention includes a step of kneading the geopolymer composition according to the first aspect and then hardening it.

[0012] FIG. 1 is a graph showing the relationship between the Z value and fluidity (mm) of the geopolymer compositions of Experimental Examples 1-2 and 5-7 in the examples.

[0013] To obtain good fluidity in geopolymer compositions, many methods have been reported to date, such as the method described in Patent Document 1, in which additives that contribute to hardening retardation are added to the composition. However, such additives are often expensive. Therefore, it would be industrially very desirable to obtain a geopolymer composition that can maintain good fluidity using as low-cost and simple a method as possible without adding additional additives.

[0014] On the other hand, geopolymer compositions generally use coal ash of various qualities as the raw active filler. To date, the quality of the raw coal ash, specifically the average Blaine value (cm ２ There have been few specific reports on the effect of SiO2 / g on the hardening rate of geopolymer compositions.

[0015] As a result of the study by the inventors, it was found that the fluidity of the geopolymer composition deteriorates as the average Blaine value of the coal ash used as a raw material increases. Therefore, if a more detailed relationship between the fluidity of the geopolymer composition and the average Blaine value of the coal ash used as a raw material is known, it is preferable because it is expected that the production cost will decrease. In this specification, "quality of coal ash" means "the average Blaine value (cm ２ / g) (in other words, "particle size of coal ash"). Therefore, the inventors conducted various studies on geopolymer compositions that can maintain good fluidity for a long period of time, regardless of the average Blaine value of the coal ash used as a raw material, and without adding any additional additives. Then, the average Blaine value (cm ２The present invention was completed by focusing on three values ​​and their relationships: the amount of coal ash (mass%) contained in the geopolymer composition, and the percentage of (mass%) water / (mass%) total active filler. Specifically, the percentage of (mass%) water / (mass%) total active filler is calculated using the formula (mass%) water / (mass%) x 100.

[0016] The average Blaine value (cm) of coal ash contained in the geopolymer composition ２ / g) is hereinafter also referred to as "X" or "average Blaine value X of coal ash." The amount of coal ash (mass%) contained in the geopolymer composition is hereinafter also referred to as "Y" or "coal ash amount Y." The percentage of (water amount (mass%)) / (total amount of active filler (mass%)) is hereinafter also referred to as "w / b" or "percentage of the ratio of water amount to total amount of active filler w / b." Specifically, it has been found that if these three values ​​in the geopolymer composition are introduced into a specific formula and the conditions specified by the formula are met, a geopolymer composition that can maintain good fluidity for a long period of time can be obtained.

[0017] Thus, according to the present invention, even when coal ash having various qualities is used as a raw material, a geopolymer composition that can maintain good fluidity for a long period of time using a low-cost and simple method can be provided.

[0018] In this specification, "water" means all water contained in (or blended with) the geopolymer composition, excluding solids. That is, as will be described in detail later, for example, when an activator, dispersant, etc. is used in the form of an aqueous solution and additional water is optionally added for the purpose of adjusting fluidity, "water" also includes water contained in the aqueous solution of the activator, water contained in the aqueous solution of the dispersant, and optionally added water.

[0019] In this specification, unless otherwise specified, "amount of coal ash (mass%)," "amount of water (mass%)," "amount of activator (mass%)," "total amount of active filler (mass%)," "amount of blast furnace slag powder (mass%)," "amount of silica fume (mass%)," "amount of fine aggregate (mass%)," "amount of coarse aggregate (mass%)," and "amount of dispersant (mass%)" refer to the amount (mass%) relative to the total mass of the geopolymer composition. In particular, "amount of dispersant (mass%)" refers to the amount (mass%) of dispersant as a solid content, and "amount of activator (mass%)" refers to the amount (mass%) of activator as a solid content before being converted into an aqueous solution.

[0020] In this specification, the "average Blaine value (cm) of coal ash" ２ / g) means the average specific surface area of ​​coal ash. Specifically, as will be described in the Examples below, the "average Blaine value (cm ２ / g) is a value measured by a specific surface area test using a Blaine air permeation device in accordance with JIS R 5201:2015.

[0021] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0022] 1. Geopolymer Composition 1-1. Conditions Satisfied by the Geopolymer Composition First, the conditions satisfied by the geopolymer composition in this embodiment will be described in detail below.

[0023] The geopolymer composition of this embodiment includes an active filler, aggregate, an activator, water, and a dispersant. The active filler includes coal ash. The dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure, and the solid content is 0.1% by mass or more and 1.5% by mass or less.

[0024] Furthermore, in the geopolymer composition of this embodiment, the formula α: Z = X × Y / (w / b) (in formula α, X is the average Blaine value of coal ash (cm ２ / g), Y represents the amount of coal ash blended (mass %), w / b represents the percentage of (the amount of water blended (mass %)) / (the total amount of the active filler blended (mass %)), and w / b is 55.0 or less), and Z calculated from this is 3,300 or less.

[0025] The conditions for the geopolymer composition defined in the above formula α are derived from the experimental results of the inventors. The details will be described in the following examples.

[0026] In the geopolymer composition of this embodiment, the three values ​​of the average Blaine value X of the coal ash, the blending amount Y of the coal ash, and the percentage w / b of the ratio of the blending amount of water to the total amount of active filler are adjusted within appropriate ranges so as to satisfy the conditions defined in the above formula α. As a result, a geopolymer composition that can maintain good fluidity for a long period of time can be obtained at low cost and with a simple method without adding additional expensive additives.

[0027] For example, based on the average Blaine value X of the coal ash used as a raw material, the percentage w / b of the ratio of the blending amount of water to the total amount of activated filler and the blending amount Y of the coal ash may each be adjusted within an appropriate range so as to satisfy the condition defined by the above formula α. In particular, from the viewpoint of lower cost and easier means, it is preferable to adjust the percentage w / b of the ratio of the blending amount of water to the total amount of activated filler within an appropriate range so as to satisfy the condition defined by the above formula α based on the average Blaine value X of the coal ash used as a raw material and the blending amount Y of the coal ash. Furthermore, from the viewpoint of the lowest cost and easiest means, it is more preferable to adjust only the blending amount of water within an appropriate range so as to satisfy the condition defined by the above formula α based on the average Blaine value X of the coal ash used as a raw material, the blending amount Y of the coal ash, and the total blending amount of the activated filler.

[0028] As described above, Z calculated from the above formula α is 3300 or less. Furthermore, Z is preferably 3250 or less. When Z is 3250 or less, a geopolymer composition that can maintain good fluidity for a long period of time can be more reliably obtained. Z calculated from the above formula α is more preferably 3200 or less. The lower limit of Z calculated from formula α is not particularly limited as long as it does not have an adverse effect on the product quality of the hardened geopolymer composition, such as insufficient strength, but is, for example, 1000 or more.

[0029] In the above formula α, if the percentage w / b of the ratio of the amount of water to the total amount of active filler exceeds 55.0, bleeding (material separation) may occur due to the excessive amount of water, and the hardened product of the geopolymer composition may have insufficient strength.

[0030] The ratio of the amount of water to the total amount of active filler (w / b) is preferably 54.0 or less. When w / b is 54.0 or less, bleeding and insufficient strength of the hardened product of the geopolymer composition can be reliably prevented. Furthermore, w / b is more preferably 53.0 or less, and even more preferably 52.0 or less.

[0031] The ratio of the amount of water to the total amount of active fillers, w / b, is preferably 20.0 or more. When w / b is 20.0 or more, a significant decrease in fluidity due to an extremely small amount of water can be prevented. w / b is more preferably 22.0 or more, and even more preferably 23.5 or more.

[0032] 1-2. Each component contained in the geopolymer composition Next, the function of each component contained in the geopolymer composition in this embodiment and its approximate blending amount (mass%) will be described in detail below.

[0033] Unless otherwise specified, the blending amount (mass%) of each component described below primarily refers to the blending amount when the geopolymer composition is used as a geopolymer mortar composition (containing only fine aggregate as aggregate). However, the blending amount of each component described below can be adjusted as needed even when the geopolymer composition is used as a geopolymer concrete composition (containing both fine and coarse aggregate as aggregate).

[0034] <Activated Filler> Activated filler is a powder containing aluminosilicate as its main component. Aluminosilicate is active against alkali. When an activator (described later) or water is added to the activated filler, the silicon and aluminum in the activated filler are partially dissolved or ionized. After dissolution, the silica component, which exists in a state close to a monomer in the alkaline silica solution, captures metal ions. As a result, a dehydration condensation reaction occurs, producing a hardened polymer compound (polymer), resulting in a hardened geopolymer composition.

[0035] In the geopolymer composition of this embodiment, the active filler includes coal ash. The coal ash may be specially pretreated to ensure uniform quality (specifically, treatment to conform to the standard for fly ash for concrete specified in JIS A 6201:2015), or may include coal ash that has not been specially pretreated. Coal ash that has not been specially pretreated is not uniform in size, composition, etc., and has variations in quality. Therefore, compositions containing coal ash that has not been specially pretreated are less likely to have stable fluidity, etc. Therefore, if coal ash that has not been specially pretreated is included, the effects of this embodiment can be more effectively achieved.

[0036] Also for example, the active filler may include, in addition to coal ash, one or more of any active fillers known to those skilled in the art that have the above functions.

[0037] Specifically, the active filler preferably contains one or more of coal ash, ground granulated blast furnace slag, and silica fume, and more preferably contains coal ash, ground granulated blast furnace slag, and silica fume. These active fillers will be described in detail below.

[0038] (Coal ash) Coal ash is mainly composed of silicon dioxide (SiO ２ ), alumina (Al ２ O ３ ) and the like. In this embodiment, the type of coal ash is not particularly limited. Specifically, as described above, the coal ash may include coal ash produced as an industrial by-product that has not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015 (hereinafter also referred to as "untreated coal ash"), or may include coal ash that has been subjected to such treatment, or may be a mixture of these coal ashes. Of these, the coal ash preferably includes untreated coal ash.

[0039] Untreated coal ash refers to coal ash that has not been subjected to any processing other than normal pulverization for transportation from the production site, or raw powder coal ash. Using untreated coal ash as an activated filler allows for efficient and effective utilization of untreated industrial by-product coal ash as a resource. Furthermore, production costs can be reduced. Such untreated coal ash can be obtained, for example, as an industrial by-product generated during coal combustion from thermal power plants, boilers, etc.

[0040] In this specification, "untreated coal ash" (or "coal ash that has not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015") refers to coal ash that has not been subjected to pulverization and / or particle size adjustment (preferably particle size adjustment). Alternatively, for example, "untreated coal ash" (or "coal ash that has not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015") refers to coal ash that is preferably produced as an industrial by-product from at least one of a thermal power plant and a boiler. Note that in one embodiment, "untreated coal ash" may be untreated coal ash consisting solely of coal ash that does not conform to the standard for fly ash for concrete specified in JIS A 6201:2015, or may be untreated coal ash that partially contains coal ash that conforms to the standard.

[0041] Specifically, coal ash includes, for example, fly ash captured from exhaust gas by a dust collector, bottom ash obtained by crushing lumps of ash at the bottom of a boiler, etc. Two or more types of coal ash, preferably untreated coal ash, may be used in combination.

[0042] When the coal ash contains untreated coal ash, the amount of untreated coal ash relative to the total mass of the coal ash is not particularly limited, but is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 100 mass%.

[0043] According to the geopolymer composition of this embodiment, even if coal ash (for example, untreated coal ash) having variations in size and quality is included, the effect of the fluidity of the geopolymer composition can be obtained. In other words, by satisfying the conditions specified in the above formula α, even if the size, composition, etc. of the coal ash used is not uniform and its quality varies to some extent, the effect of maintaining good fluidity for a long period of time can be obtained.

[0044] The average Blaine value X of coal ash is 3000 cm ２ / g or more, and２ / g or more. ２ / g or more, it is expected that this will lead to a decrease in the fluidity of the geopolymer composition. However, according to this embodiment, ２ Based on the average Blaine value X of coal ash of 1 / g or more, the percentage w / b of the ratio of the amount of water to the total amount of active filler and the amount Y of coal ash can be adjusted within appropriate ranges to satisfy the conditions defined in the above formula α. As a result, even a geopolymer composition using coal ash with a relatively large average Blaine value X can unexpectedly maintain good fluidity for a long period of time.

[0045] As described above, the coal ash blending amount Y is not particularly limited as long as it satisfies the condition defined by the above formula α. For example, the coal ash blending amount Y is preferably 10 mass % to 50 mass %, more preferably 15 mass % to 30 mass %, and even more preferably 18 mass % to 25 mass %.

[0046] The amount of coal ash relative to the total mass of the activated filler is not particularly limited as long as it satisfies the conditions defined by the above formula α. For example, the amount of coal ash relative to the total mass of the activated filler is preferably 3% by mass to 77% by mass. When the amount of coal ash relative to the total mass of the activated filler is 3% by mass or more, coal ash, an industrial by-product, can be effectively utilized as a resource, and a geopolymer composition that is suitable from an environmental and cost perspective can be obtained. Furthermore, when the amount of coal ash relative to the total mass of the activated filler is 77% by mass or less, the amount of active filler, which is related to the strength of the hardened body, such as ground granulated blast furnace slag, is not insufficient, and a hardened body with sufficient strength can be obtained.

[0047] The amount of coal ash to be blended relative to the total mass of the active filler is more preferably 40 mass % or more, and even more preferably 50 mass % or more.

[0048] (Ground granulated blast furnace slag) Ground granulated blast furnace slag contains calcium oxide (CaO), silicon dioxide (SiO ２ ), alumina (Al ２ O ３) etc.

[0049] When ground granulated blast furnace slag is included as an active filler, any ground granulated blast furnace slag known to those skilled in the art can be used. For example, ground granulated blast furnace slag can be obtained by pulverizing granulated blast furnace slag. Granulated blast furnace slag is obtained as a by-product when refining iron in a blast furnace. Commercially available ground granulated blast furnace slag may also be used. Examples of commercially available ground granulated blast furnace slag include ground granulated blast furnace slag that meets the JIS A 6206 standard for ground granulated blast furnace slag 4000. Examples of such commercially available ground granulated blast furnace slag include "K-MENT" sold by Kobe Steel Slag Products Co., Ltd. and "ESMENT" manufactured by Nippon Steel Blast Furnace Cement Co., Ltd.

[0050] When ground granulated blast furnace slag is used as the active filler, the amount of ground granulated blast furnace slag relative to the total mass of the active filler is not particularly limited as long as it satisfies the conditions defined by the above formula α. For example, the amount of ground granulated blast furnace slag relative to the total mass of the active filler is preferably 3% by mass to 77% by mass. When the amount of ground granulated blast furnace slag is 3% by mass or more, a hardened body with the desired high strength can be easily obtained in a short period of time. When the amount of ground granulated blast furnace slag is 77% by mass or less, it becomes easier to maintain good fluidity of the geopolymer composition for a long period of time.

[0051] The amount of ground granulated blast furnace slag relative to the total mass of the active filler is preferably 10% by mass or more, and even more preferably 25% by mass or more, and more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0052] (Silica fume) Silica fume is a material that contains silicon dioxide (SiO ２ Specifically, silica fume is a highly pure silicon dioxide (SiO ２ ) amorphous spherical fine particles.

[0053] When silica fume is included as an active filler, any silica fume known to those skilled in the art can be used. For example, silica fume can be obtained as a by-product of collecting dust in exhaust gas generated during the production of ferrosilicon, metallic silicon, electrolytic zirconia, etc. Commercially available silica fume can also be used.

[0054] Silica fume not only functions as a normal active filler, i.e., it initiates the dehydration condensation polymerization reaction, which leads to improved strength of the hardened body, but also enhances the fluidity of the geopolymer composition. This is because silica fume's spherical and fine shape allows other coarse particles to flow.

[0055] When silica fume is included as an active filler, the amount of silica fume relative to the total mass of the active filler is not particularly limited as long as the condition defined by the above formula α is satisfied. For example, the amount of silica fume relative to the total mass of the active filler is preferably 1 mass% to 20 mass%. When the amount of silica fume is 1 mass% or more, the above-mentioned effect of silica fume can be effectively exerted. Furthermore, since silica fume is expensive, when the amount of silica fume is 20 mass% or less, the production cost of the geopolymer composition can be further reduced.

[0056] The amount of silica fume relative to the total mass of the active filler is preferably 3% by mass or more, and even more preferably 5% by mass or more, and more preferably 15% by mass or less, and even more preferably 13% by mass or less, relative to the total mass of the active filler.

[0057] (Other active fillers) Other active fillers that can be included in the geopolymer composition of this embodiment include, for example, red mud, feldspars, micas, zeolites, perlite, clay minerals, kaolin, metakaolin, sewage sludge, and the like.

[0058] The total amount (mass %) of active filler relative to the total mass of the geopolymer composition can be determined not only by the conditions specified in the above formula α, but also by the ratio of the amount of activator in the geopolymer composition. Generally, the activator as a solid is used in the form of an aqueous solution. Specifically, for example, when an alkaline aqueous solution of approximately 6 mol / L to 10 mol / L is used as the activator aqueous solution, the ratio of the amount of activator as an aqueous solution to the total amount of active filler (i.e., activator (mass) as an aqueous solution / active filler (total mass)) is preferably 4% to 30%. In this case, if the activator (mass) / active filler (total mass) as an aqueous solution is 4% or more, the dehydration condensation reaction of the active filler can be sufficiently generated, ultimately resulting in a hardened geopolymer with sufficient strength. Furthermore, in this case, if the activator (mass) / active filler (total mass) as an aqueous solution is 30% or less, false coagulation caused by an excessive amount of activator can be prevented.

[0059] Similarly, in this case, the activator (mass) / active filler (total mass) as an aqueous solution is preferably 10% or more, and even more preferably 15% or more, and in this case, the activator (mass) / active filler (total mass) as an aqueous solution is preferably 25% or less, and even more preferably 20% or less.

[0060] The above-mentioned preferable ratio varies somewhat depending on the type and concentration of the activator, but the activator (mass) / active filler (total mass) as an aqueous solution may be appropriately adjusted within a range in which the active filler reacts sufficiently and no false coagulation occurs.

[0061] In addition, the total amount (mass%) of active filler relative to the total mass of the geopolymer composition varies depending on the type of geopolymer hardened body, which is the final product. Therefore, the total amount of active filler can be adjusted appropriately to suit the type of geopolymer hardened body desired. For example, the total amount of active filler is approximately 20% to 60% by mass relative to the total mass of the geopolymer composition. Examples of types of geopolymer hardened bodies include mortar and concrete, as mentioned above.

[0062] <Aggregate> Any aggregate known to those skilled in the art can be used as the aggregate. For example, commonly known aggregates used in the production of concrete, mortar, artificial stone, etc. can be used. That is, the geopolymer composition of this embodiment can be applied to both geopolymer mortar compositions containing fine aggregate but not coarse aggregate, and geopolymer concrete compositions containing fine aggregate and coarse aggregate.

[0063] At least 85% of the fine aggregate is 5 mm or less in diameter. At least 85% of the coarse aggregate is 5 mm or more in diameter. The type of aggregate may be selected appropriately depending on the intended use of the final product, the hardened geopolymer. For example, two or more types of aggregate may be used, such as a combination of fine and coarse aggregates.

[0064] Examples of fine aggregate include blast furnace slag fine aggregate and fine aggregate such as general silica sand, which is a natural aggregate. Of these, it is preferable to use blast furnace slag fine aggregate. Blast furnace slag fine aggregate has latent hydraulic properties. The latent hydraulic properties are due to the silicon dioxide (SiO ２ ), alumina (Al ２ O ３ ) and other factors, which produces hydrates, which increases the strength of the hardened product. Therefore, by using blast furnace slag fine aggregate as an aggregate, it is possible to increase the long-term strength of the final product, the hardened geopolymer.

[0065] Blast furnace slag fine aggregate is specified in JIS A 5011-1:2018. Alternatively, commercially available blast furnace slag fine aggregate may be used. Examples of commercially available blast furnace slag fine aggregate include "Shinko Sand" sold by Kobelco Slag Products Co., Ltd. and blast furnace slag fine aggregate manufactured by JFE Mineral Co., Ltd.

[0066] As the coarse aggregate, it is preferable to use blast furnace slag coarse aggregate made from blast furnace slag. When blast furnace slag coarse aggregate and / or the above-mentioned blast furnace slag fine aggregate are used as the aggregate, industrial by-products can be effectively utilized as resources, and a highly environmentally friendly geopolymer composition can be obtained. Furthermore, production costs can be reduced.

[0067] The amount of aggregate to be mixed is not particularly limited and can be adjusted according to the intended use of the hardened geopolymer body, which is the final product. For example, the amount of aggregate to be mixed is preferably 30% to 70% by mass. When the amount of aggregate is 30% by mass or more, separation of the aggregate and the geopolymer composition paste can be prevented, making it easier to form a uniform hardened body. When the amount of aggregate is 70% by mass or less, it becomes easier to maintain good fluidity of the geopolymer composition over a long period of time.

[0068] The amount of aggregate is preferably 40% by weight or more, more preferably 50% by weight or more, and more preferably 65% ​​by weight or less, more preferably 60% by weight or less, based on the total weight of the geopolymer composition.

[0069] <Activator> The activator is a component that initiates polymerization through a dehydration condensation reaction of the activated filler. Typically, the activator as a solid is used in the form of an aqueous solution. Specifically, the activator's aqueous solution is an alkaline solution that comes into contact with the aluminosilicate in the activated filler and dissolves silicon and aluminum. Therefore, from the perspective of causing a dehydration condensation reaction, the activator as a solid reduces the fluidity of the geopolymer composition over time after kneading. On the other hand, from the perspective of being used in the form of an aqueous solution, the activator in the form of an aqueous solution also contributes to improving the fluidity of the geopolymer composition immediately after kneading.

[0070] The aqueous solution of the activator is not particularly limited as long as it is a commonly used one, and for example, an aqueous solution of sodium hydroxide, water glass (sodium silicate), potassium silicate, etc. may be used. Alternatively, a commercially available activator containing an alkali source may be used as the activator (in solid or aqueous solution form). Examples of such commercially available activators include the Mastercrete AC series manufactured by Pozzolith Solutions.

[0071] The concentration of the aqueous alkaline solution of the activator must be adjusted appropriately depending on the type and amount of the activator, but is preferably 4 mol / L to 12 mol / L, for example. When the concentration of the aqueous activator solution is 4 mol / L or more, the dehydration condensation reaction in the activated filler can be sufficiently induced. When the concentration of the aqueous activator solution is 12 mol / L or less, the generation of excessive heat of fusion due to high concentrations can be avoided.

[0072] The concentration of the alkaline aqueous solution, which is the aqueous solution of the activator, must be adjusted appropriately depending on the type and amount of the activator, but is preferably 5 mol / L or more, and more preferably 6 mol / L or more.The concentration of the alkaline aqueous solution, which is the aqueous solution of the activator, must be adjusted appropriately depending on the type and amount of the activator, but is more preferably 11 mol / L or less, and more preferably 10 mol / L or less.

[0073] As described above, when the activator is in the form of an aqueous solution, the amount of water contained in the aqueous solution of the activator is adjusted to an appropriate range so that the amount of water (the total amount of water contained in the geopolymer composition) satisfies the conditions defined in the above formula α.

[0074] At the same time, as described above, the amount of activator to be incorporated in the aqueous solution form can also be determined from the ratio of the total amount of active filler to the total mass of the geopolymer composition.

[0075] <Water> As mentioned above, water refers to all water contained in the geopolymer composition. In other words, in this specification, the "water content (mass%)" refers to the amount of water contained in the aqueous solution of the activator when the activator is in the form of a solid aqueous solution, the amount of water contained in the aqueous solution of the dispersant when the dispersant is in the form of a solid aqueous solution, the amount of water optionally added separately for purposes such as adjusting the fluidity of the geopolymer composition (hereinafter referred to as "externally added water"), and the amount of water optionally contained in other materials. The type of water is not particularly limited, and examples include tap water, ion-exchanged water, etc. The pH and temperature of the water are also arbitrary and can be adjusted to general values ​​as appropriate depending on the type and amount of each component contained in the geopolymer composition.

[0076] Water contributes to the fluidity of the geopolymer composition. As mentioned above, ensuring the fluidity of the geopolymer composition by adjusting only the amount of water is the lowest-cost and easiest way to maintain fluidity. However, excessively increasing the amount of water may cause bleeding or insufficient strength in the hardened geopolymer composition product. However, the geopolymer composition of this embodiment contains a polycondensate-based dispersant containing a polyalkylene glycol monophenyl ether (described below) as a dispersant. Therefore, compared to general geopolymer compositions, the amount of water required to ensure good fluidity can be reduced.

[0077] Specifically, the amount of water to be blended is not particularly limited as long as it satisfies the condition defined by the above formula α. For example, as described above, the amount of water to be blended may be adjusted within an appropriate range based on the average Blaine value X of the coal ash used as a raw material, the blending amount Y of the coal ash, and the total blending amount of the active filler, so as to satisfy the condition defined by the above formula α.

[0078] More specifically, the amount of water is preferably 7.0% by mass to 13.5% by mass, more preferably 7.5% by mass to 13.0% by mass, even more preferably 8.0% by mass to 12.5% ​​by mass, and particularly preferably 8.5% by mass to 12.0% by mass.

[0079] <Dispersant> The geopolymer composition in this embodiment contains a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure. Specifically, this solid dispersant is often used as a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure in the form of an aqueous solution.

[0080] The inclusion of this dispersant in the geopolymer composition inhibits contact between particles in the geopolymer composition. As a result, the hardening reaction of the geopolymer composition can be slowed down. In addition, the hardening reaction retardation effect of this dispersant disappears within a few hours. Therefore, when a geopolymer composition contains this dispersant, it can achieve both good fluidity maintenance over a long period of time and subsequent strength development.

[0081] In this specification, the term "polycondensate dispersant containing polyalkylene glycol monophenyl ether as a partial structure" is not particularly limited as long as it is a polymer having the above-mentioned effect and a specified structure. Examples of such dispersants include polymers containing polycondensates containing the following structural units A, B, C, and D.

[0082] Structural unit A: At least one polyethylene glycol monophenyl ether represented by the following formula (1): [Chemical Formula 1] [wherein, m is an integer of 3 to 280]

[0083] Structural unit B: a cyclic compound having at least one hydroxyl group and a derivative thereof, for example, at least one aromatic compound selected from the group consisting of benzene-1,2-diol, benzene-1,2,3-triol, 2-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, 3-hydroxyphthalic acid, 2,3-dihydroxybenzenesulfonic acid, 3,4-dihydroxybenzenesulfonic acid, 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,2-dihydroxynaphthalene-5-sulfonic acid, 1,2-dihydroxynaphthalene-6-sulfonic acid, 2,3-dihydroxynaphthalene-5-sulfonic acid, 2,3-dihydroxynaphthalene-6-sulfonic acid, and mixtures thereof.

[0084] Structural unit C: phenol, polyethylene glycol monophenyl ether having 1 or 2 ethylene oxide repeating units, or a phenoxyethyl derivative containing a phosphate or phosphonate, such as at least one other aromatic compound selected from the group consisting of phenol, 2-phenoxyethanol, 2-phenoxyethyl phosphate, 2-phenoxyethyl phosphonate, 2-phenoxyacetic acid, 2-(2-phenoxyethoxy)ethanol, 2-(2-phenoxyethoxy)ethyl phosphate, 2-(2-phenoxyethoxy)ethyl phosphonate, 2-[4-(2-hydroxyethoxy)phenoxy]ethyl phosphate, 2-[4-(2-hydroxyethoxy)phenoxy]ethyl phosphonate, 2-[4-(2-phosphonatooxyethoxy)phenoxy]ethyl phosphate, 2-[4-(2-phosphonatooxyethoxy)phenoxy]ethyl phosphonate, methoxyphenol, and mixtures thereof.

[0085] Structural unit D: aldehydes, for example, at least one aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, glyoxylic acid, benzaldehyde, benzaldehyde sulfonic acid, benzaldehyde disulfonic acid, vanillin, isovanillin, and mixtures thereof.

[0086] The solid content of the dispersant is 0.1% to 1.5% by mass. When the solid content of the dispersant is 0.1% by mass or more, the dispersant's action can be effectively exerted, achieving both high fluidity over a long period of time and high strength in a short period of time. When the solid content of the dispersant is 1.5% by mass or less, separation and bleeding of the geopolymer composition due to the addition of excessive dispersant can be suppressed.

[0087] The solid content of the dispersant is preferably 0.15% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.25% by mass or more, and is preferably 1.2% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.80% by mass or less.

[0088] <Other Materials> The geopolymer composition of this embodiment may contain any material that can be generally added as a raw material for mortar, concrete, etc., as long as it does not impair the effect of maintaining good fluidity over a long period of time. For example, it may contain an inert filler, which is a powder that is not active against alkali, various additives, etc. Examples of inert fillers include cement and calcium carbonate. The various additives are not particularly limited, but include conventionally known components such as fluidizers, shrinkage reducing agents, rust inhibitors, waterproofing agents, antifoaming agents, dust reducing agents, and pigments.

[0089] 2. Method for Preparing Geopolymer Composition The geopolymer composition of this embodiment can be prepared by any method known to those skilled in the art. For example, the method for preparing the geopolymer composition includes a powder mixing step and a subsequent kneading step. In the powder mixing step, the main powder raw materials, an activated filler (e.g., an activated filler including coal ash, ground granulated blast furnace slag, and silica fume) and an aggregate (e.g., at least one of fine aggregate and coarse aggregate), are mixed in a predetermined blending amount. In the subsequent kneading step, externally added water and an activator and dispersant in aqueous solution are further added to the powder mixture in a predetermined blending amount, and the mixture is mixed and kneaded. The mixing and kneading methods are not particularly limited, and any method known to those skilled in the art using a mixer or the like may be used.

[0090] In addition, in the method for preparing a geopolymer composition, a powder mixture may be prepared in advance by adding and mixing a predetermined amount of the main powder raw materials, such as an activated filler (e.g., an activated filler including coal ash, blast furnace slag powder, and silica fume), an aggregate (e.g., at least one of fine aggregate and coarse aggregate), an activator, and a dispersant, and the powder mixture may be used as a premixed geopolymer composition. Specifically, before construction, work, etc., water is added to the premixed geopolymer composition in a predetermined amount, and the mixture is mixed and kneaded. This allows for easy on-site preparation of any desired amount of geopolymer composition. Alternatively, when the activator and / or dispersant are prepared in the form of an aqueous solution and used, a powder mixture may be prepared in advance by adding and mixing a predetermined amount of the activated filler and aggregate, which are materials other than the activator aqueous solution and / or the dispersant aqueous solution, and the prepared powder mixture may be used as a premixed geopolymer composition. In this case, the activator aqueous solution and / or dispersant aqueous solution, and optionally externally added water, are added to the premix geopolymer composition in predetermined amounts and mixed and kneaded prior to construction, work, etc. Alternatively, if the activator and / or dispersant is prepared in advance in the form of an aqueous solution, the active filler and aggregate, and a portion of one or more of the aforementioned aqueous solutions may be added and mixed in predetermined amounts to form a premix geopolymer composition or its precursor. In this case, the remaining activator aqueous solution and / or dispersant aqueous solution, and optionally externally added water, are added to the premix geopolymer composition or its precursor in predetermined amounts and mixed and kneaded prior to construction, work, etc.

[0091] The geopolymer composition of this embodiment can maintain good fluidity for a long period of time using a low-cost and simple method, even when coal ash of various qualities is used as a raw material. Maintaining good fluidity for a long period of time allows the geopolymer composition to be easily handled at the manufacturing site of the hardened product. In addition, the geopolymer composition of this embodiment can be obtained by simply adjusting the amount of water blended, which is considered to be the cheapest and easiest method. Therefore, this is extremely advantageous industrially from the perspective of reducing the manufacturing cost of hardened geopolymer compositions.

[0092] 3. Geopolymer hardened body and method for manufacturing the geopolymer hardened body The geopolymer hardened body in this embodiment is obtained by hardening the geopolymer composition in the above-mentioned embodiment. The geopolymer hardened body has any shape that can be formed by any molding method, construction method, etc.

[0093] The hardened geopolymer material is preferably, but not limited to, mortar or concrete. More specifically, the hardened geopolymer material includes, for example, road or bank blocks, blocks for storm drains or irrigation channels, tiles, bricks, sewer pipes, precast products such as piles, poles, and sleepers, cast-in-place products such as cast-in-place concrete, shotcrete, concrete repair, and dam concrete.

[0094] The method for producing a hardened geopolymer in this embodiment includes a step of kneading the geopolymer composition in the above-described embodiment and then hardening it. Specifically, the kneaded geopolymer composition is first molded or applied using any method known to those skilled in the art, such as molding using a formwork, troweling in plastering work, spraying, or pasting. Then, the molded or applied geopolymer composition can be hardened by curing.

[0095] This curing step preferably includes air curing. As mentioned above, the geopolymer composition contains a polycondensate dispersant containing polyalkylene glycol monophenyl ether as a partial structure as a dispersant. Therefore, the amount of water can be reduced compared to general geopolymer compositions. As a result, by performing conventional curing, such as air curing and sealing, a geopolymer with sufficient strength can be produced in a shorter time than usual, without performing complex processes such as steam curing, which are expensive and have a significant environmental impact.

[0096] In addition, in order to obtain a high-strength geopolymer hardened body in a shorter period of time, air curing and steam curing (preferably short-term steam curing) may be combined in the hardening process.

[0097] In addition, when producing a hardened geopolymer body using a formwork, it is preferable to include applying a release agent or the like to the formwork in advance. The release agent is not particularly limited as long as it is any release agent known to those skilled in the art that imparts release properties to the hardened geopolymer body.

[0098] As described above, this specification discloses various aspects of the technology, the main aspects of which are summarized below.

[0099] The geopolymer composition according to the first aspect of the present invention is a geopolymer composition comprising an active filler, an aggregate, an activator, water, and a dispersant, wherein the active filler comprises coal ash, and the dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure, and the amount of solid content is 0.1 mass% or more and 1.5 mass% or less with respect to the total mass of the geopolymer composition, and in the geopolymer composition, the formula α: Z = X × Y / (w / b) (in formula α, X is the average Blaine value (cm ２ / g), Y represents the blending amount (mass%) of the coal ash, w / b represents the percentage of (the blending amount (mass%) of the water) / (the blending amount (mass%) of the total active filler), and w / b is 55.0 or less), and Z calculated from this is 3,300 or less.

[0100] A geopolymer composition according to a second aspect of the present invention is the geopolymer composition according to the first aspect, wherein the coal ash is not treated to comply with the standard for fly ash for concrete specified in JIS A 6201:2015.

[0101] A geopolymer composition according to a third aspect of the present invention is a geopolymer composition according to the first or second aspect, wherein the average Blaine value (cm ２ / g) is 5000 cm ２ / g or more.

[0102] The geopolymer hardened body according to the fourth aspect of the present invention is formed by hardening the geopolymer composition according to any one of the first to third aspects.

[0103] A method for producing a geopolymer hardened body according to a fifth aspect of the present invention includes a step of kneading a geopolymer composition according to any one of the first to third aspects and then hardening it.

[0104] A method for producing a hardened geopolymer according to a sixth aspect of the present invention is the method for producing a hardened geopolymer according to the fifth aspect, wherein the hardening step includes air curing.

[0105] A method for producing a hardened geopolymer according to a seventh aspect of the present invention is a method for producing a hardened geopolymer according to the fifth or sixth aspect, wherein the hardened geopolymer is mortar or concrete.

[0106] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0107] In this example, in order to investigate the detailed relationship between the fluidity of the geopolymer composition and the average Blaine value of the coal ash, first, various geopolymer compositions were prepared by varying the average Blaine value of the coal ash used as a raw material, the amount of coal ash blended, etc. Then, fluidity tests and bleeding tests were performed on the geopolymer compositions to evaluate the various geopolymer compositions.

[0108] In this example, the average Blaine value (cm ２ / g) was measured by a specific surface area test in accordance with JIS R 5201:2015 using a Blaine air permeability device (manufactured by Daiken Rikagaku Kikai Co., Ltd., "Blaine air permeability particle size meter").

[0109] 1. Preparation of Geopolymer Composition First, the raw materials of the geopolymer compositions used in each experimental example and their preparation methods will be described in detail below.

[0110] [Raw materials for geopolymer composition] The raw materials for the geopolymer composition used in each experimental example are as follows: Coal ash 1 (untreated coal ash): average Blaine value 5020 cm ２ / g Coal ash 2 (untreated coal ash): average Blaine value 3000 cm ２ / g Finely ground blast furnace slag: "K-MENT" (specific surface area 4700 cm) manufactured by Kobe Steel Slag Products Co., Ltd. ２ / g) Silica fume: "Mastercrete SF 5000" manufactured by Pozzolith Solutions, bulk density: 2.2 g / cm3 Fine aggregate (blast furnace slag fine aggregate): "Shinko Sand" manufactured by Kobe Steel Slag Products Co., Ltd. (maximum particle size 2.5 mm, sieve passing mass fraction 55% when the nominal size of the sieve is 0.6 mm) Coarse aggregate: Crushed hard sandstone from Omi (maximum size 20 mm, surface dry density 2.65 g / cm3) ３) Externally added water: tap water Aqueous solution of activator: "Mastercrete AC 5025" manufactured by Pozzolith Solutions Aqueous solution of dispersant: Aqueous solution of the compound described in Example 5 of Japanese Patent No. 6290176 (This aqueous solution of the compound can be prepared by the following method. First, 300 parts by weight of poly(ethylene oxide) monophenyl ether (average molecular weight 2000 g / mol), 46.2 parts by weight of 3,4-dihydroxybenzoic acid, 33 parts by weight of 2-phenoxyethyl phosphate, and 19.5 parts by weight of paraformaldehyde are added to a heatable reactor equipped with a stirrer and a metering pump. 9 parts by weight are charged under nitrogen at 90°C. The reaction mixture is then heated to 110°C with stirring, and 41 parts by weight of methanesulfonic acid (70%) are then added within 25 minutes, so that the reaction temperature does not exceed 115°C. After metering, the reaction mixture is stirred for a further 2.5 hours at 110°C. The reaction mixture is then cooled and mixed with 350 parts by weight of water, and the mixture is heated for 30 minutes at 100°C. Finally, it is neutralized with 50% caustic soda solution to a pH value of about 7.0.

[0111] [Method for Preparing Geopolymer Compositions] The above raw materials were mixed in the respective amounts (% by mass) shown in Table 1 below (relative to the total mass of the composition) to prepare the geopolymer compositions in Experimental Examples 1 to 8. Specifically, first, coal ash 1 or coal ash 2, ground granulated blast furnace slag, and silica fume were mixed as active fillers in the respective amounts shown in Table 1 below. Next, fine aggregate or both fine and coarse aggregates were added to this mixed powder and mixed. Finally, externally added water, an aqueous solution of an activator, and an aqueous solution of a dispersant were added to the mixture in the respective amounts and mixed using a Hobart mixer. The geopolymer compositions (geopolymer concrete compositions) in Experimental Examples 3 and 4 were prepared using a forced twin-shaft mixer. Note that the amounts of activator and dispersant shown in Table 1 below are the amounts (% by mass) of solids. The amount of water listed in Table 1 is the total amount of water (mass%) including the externally added water, the water contained in the aqueous solution of the activator, and the water contained in the aqueous solution of the dispersant.

[0112] [Table 1]

[0113] In Table 1 above and Tables 2 to 5 shown later, Experimental Examples 1 to 8 are classified as Examples 1 to 6 or Comparative Examples 1 to 2, respectively. This classification is derived from the fluidity evaluation results of "2. Evaluation of Geopolymer Composition" and "3. Consideration of Geopolymer Composition in the Present Embodiment" described below.

[0114] 2. Evaluation of Geopolymer Composition Using each geopolymer composition prepared as described above, a fluidity test and a bleeding test were performed to evaluate the geopolymer composition. The test method and test results are described in detail below.

[0115] [Geopolymer Composition Fluidity Test 1] The fluidity of the geopolymer compositions (geopolymer mortar compositions) of Experimental Examples 1, 2, 5, 6, and 7 was measured in accordance with the flow test specified in JIS R 5201:2015 (Physical Testing Methods for Cement). However, the flow test was performed without tamping. If the measurement results showed that a high fluidity of 200 mm or more was maintained for 60 minutes, the fluidity of the geopolymer composition was evaluated as "good." If this measurement condition was not met, the fluidity of the geopolymer composition was evaluated as "not good."

[0116] [Geopolymer Composition Bleeding Test] The geopolymer composition bleeding test was performed as follows. After kneading the raw materials of the geopolymer composition with a total volume of 1.5 L, the kneaded composition was left for 1 hour. After 1 hour, the water floating on the surface of the left-standing composition was extracted with a dropper. Then, the volume of the extracted water was measured using a measuring cylinder, and the degree of bleeding was evaluated.

[0117] The results of fluidity test 1 and the bleeding test for the geopolymer compositions (geopolymer mortar compositions) of Experimental Examples 1, 2, 5, 6, and 7 are summarized in Table 2 below. The geopolymer composition of Experimental Example 8 had bleeding in the first place, so its fluidity was not measurable.

[0118] [Table 2]

[0119] [Geopolymer Composition Fluidity Test 2] The fluidity of the geopolymer compositions (geopolymer concrete compositions) of Experimental Examples 3 and 4 containing coarse aggregate was measured in accordance with the concrete slump flow test specified in JIS A 1150:2020. Specifically, the diameter of the concrete expanded from the start of slump cone lifting until the stop was confirmed, i.e., slump flow (cm), and the time to reach 50 cm of flow (T50 (seconds)) were measured at 0, 45, 90, and 135 minutes. If the slump flow was 60 cm or more and T50 was within 10 seconds, the fluidity of the geopolymer composition was evaluated as "good." If these measurement conditions were not met, the fluidity of the geopolymer composition was evaluated as "poor."

[0120] The bleeding test of the geopolymer compositions (geopolymer concrete compositions) of Experimental Examples 3 and 4 was conducted in accordance with JIS A 1132: 2020. The results of fluidity test 2 and the bleeding test of the geopolymer compositions (geopolymer concrete compositions) of Experimental Examples 3 and 4 are summarized in Table 3 below.

[0121] [Table 3]

[0122] 3. Consideration of the Geopolymer Composition in the Present Embodiment Based on the results of the above experimental examples, the inventors investigated the detailed relationship between the fluidity of the geopolymer composition and the average Blaine value of the coal ash. They focused on the average Blaine value X of the coal ash and the amount of coal ash Y, which are the main factors that reduce the fluidity of the composition, and the percentage w / b, which is the ratio of the amount of water to the total amount of active filler, which is the main factor that improves the fluidity of the composition. Furthermore, they further investigated the formula α: Z = (X × Y) / (w / b) created using these values ​​and the value calculated by formula α.

[0123] Table 4 below shows the average Blaine value X of the coal ash, the blending amount Y of the coal ash, the percentage w / b of the blending amount of water to the total amount of active filler, the value calculated by the formula α: Z = (X × Y) / (w / b), and the fluidity evaluation results for each experimental example.

[0124] [Table 4]

[0125] The graph in Figure 1 shows the relationship between the Z value and fluidity (mm) of the geopolymer compositions of Experimental Examples 1-2 and 5-7 in the examples. The straight line shown in Figure 1 is a regression line obtained from the Z value calculated from the formula α: Z = (X × Y) / (w / b) in Experimental Examples 1-2 and 5-7 and the fluidity measurement results at 60 minutes shown in Table 2 above. The dashed line shown in Figure 1 indicates that, based on the regression line, the Z value at 200 mm, which is the standard for good fluidity, is approximately 3300.

[0126] As shown in Table 4 and FIG. 1, the average Blaine value X of the coal ash is 3000 (cm ２ The geopolymer compositions of Experimental Example 5 and Experimental Example 6 (Example 5 and Example 6) with a water content of 10 ... ２ This is presumably because the value is large (1 / g).

[0127] On the other hand, the average Blaine value X of the coal ash was 5020 (cm ２The geopolymer compositions of Experimental Examples 1 to 4 (Examples 1 to 4), which have a ρ / g ratio, maintained good fluidity for a long period of time. This is because the geopolymer compositions of Experimental Examples 1 to 4 (Examples 1 to 4) have a larger amount of water blended compared to the geopolymer composition of Experimental Example 7 (Comparative Example 1), and as a result, the percentage w / b ratio of the amount of water blended to the total amount of active filler has increased to within an appropriate range for ensuring good fluidity of approximately 31.8 to 51.4. In addition, the average Blaine value X of the coal ash is 5020 (cm ２ In the geopolymer composition of Experimental Example 8 (Comparative Example 2), the ratio of the amount of water to the total amount of active filler (w / b) was 60.2, which was too large. It can be assumed that bleeding occurred.

[0128] Thus, even when coal ash with various average Blaine values ​​X is used as a raw material, the geopolymer composition can maintain good fluidity over a long period of time by adjusting the percentage (w / b) of the ratio of the amount of water to the total amount of active filler within an appropriate range. In particular, the percentage (w / b) of the ratio of the amount of water to the total amount of active filler can be inexpensively and easily controlled by adjusting only the amount of water. This ultimately leads to reduced manufacturing costs for hardened geopolymer composition products, making it highly advantageous from an industrial perspective.

[0129] More specifically, from the results of Table 4 and Figure 1 above, in order for the geopolymer composition to maintain good fluidity over a long period of time, the average Blaine value X of the coal ash, the amount of coal ash Y, and the percentage w / b of the ratio of the amount of water to the total amount of active filler are adjusted to be within an appropriate range, and Z calculated by the formula α: Z = (X × Y) / (w / b) is controlled to 3300 or less. At the same time, based on the results of Experimental Example 3 (Example 3), in order to prevent bleeding due to excessive water increase, it can also be seen that it is necessary to control the percentage w / b of the ratio of the amount of water to the total amount of active filler so that it does not exceed approximately 55.0.

[0130] As shown in Table 4 above, in the geopolymer composition of Experimental Example 7 (Comparative Example 1), Z calculated by the formula α: Z = (X × Y) / (w / b) exceeds 3300, resulting in poor fluidity. In addition, in the geopolymer composition of Experimental Example 8 (Comparative Example 2), the percentage w / b of the ratio of the amount of water to the total amount of active filler exceeds 55.0, resulting in bleeding. Note that while the graph relating to formula α in Figure 1 is based on the results of an experimental example of a geopolymer mortar composition, those skilled in the art can expect that the fluidity conditions of the composition can be similarly defined for geopolymer compositions applied to other hardened products (e.g., geopolymer concrete compositions).

[0131] 4. Evaluation of the strength of the hardened geopolymer composition Furthermore, to confirm the strength of the hardened geopolymer composition, which is important as a product quality, we also conducted an uniaxial compressive strength test of the hardened geopolymer composition.

[0132] [Uniaxial compressive strength test of hardened geopolymer composition] The uniaxial compressive strength of the hardened geopolymer composition was measured by the following method. Each prepared geopolymer composition was placed in a cylindrical mold having a diameter of 5 cm and a height of 10 cm (Experimental Examples 1, 2, 5, and 6) or a cylindrical mold having a diameter of 10 cm and a height of 20 cm (Experimental Examples 3 and 4), and the molded product was sealed and cured until the age shown in Table 2 below. After demolding, the uniaxial compressive strength of the molded product was measured in accordance with JIS A 1108:2018.

[0133] The results of the unconfined compressive strength test at each age (strength measurement date) are shown in Table 5 below. The geopolymer composition of Experimental Example 7 (Comparative Example 1) had low fluidity and could not be enclosed in a cylindrical mold for compressive strength measurement, so the strength could not be measured. The geopolymer composition of Experimental Example 8 (Comparative Example 2) had bleeding in the first place, so the quality of the hardened geopolymer composition product cannot be guaranteed.

[0134] [Table 5]

[0135] From the results of Table 5 above, the geopolymer compositions of Experimental Examples 1 to 6 (Examples 1 to 6) reached a strength of 20 MPa or more at 7 days old, even when cured at room temperature instead of steam curing, which is costly and environmentally burdensome. In particular, the geopolymer compositions of Experimental Examples 1 and 2 (Examples 1 and 2) reached a significantly higher strength of 36 MPa or more at 7 days old, compared to the geopolymer composition of Experimental Example 7 (Comparative Example 1), which has the same average Blaine value X of coal ash. This is thought to be because the water content was increased within an appropriate range where bleeding does not occur, and the geopolymer composition contains a specific dispersant.

[0136] Thus, the geopolymer composition of this embodiment can maintain good fluidity for a long period of time at low cost, even when coal ash of various qualities is used as a raw material. It has been found that high strength, which is important as the quality of the hardened product, can also be obtained.

[0137] This application is based on Japanese Patent Application No. 2024-055269 filed on March 29, 2024, the contents of which are incorporated herein by reference.

[0138] The embodiments and examples disclosed herein should be understood to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0139] According to an embodiment of the present invention, a geopolymer composition that can maintain good fluidity for a long period of time using coal ash of various qualities as a raw material can be provided at low cost and simply. Therefore, it is industrially very preferable from the viewpoint of reducing production costs, etc.

Claims

A geopolymer composition comprising an active filler, an aggregate, an activator, water, and a dispersant, wherein the active filler comprises coal ash, and the dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure, and the amount of solid content thereof is 0.1 mass% or more and 1.5 mass% or less with respect to the total mass of the geopolymer composition, and in the geopolymer composition, the formula α: Z = X × Y / (w / b) (in formula α, X is the average Blaine value (cm ２ / g), Y represents the amount of coal ash blended (mass%), and w / b represents the percentage of (the amount of water blended (mass%)) / (the total amount of active filler blended (mass%)), and w / b is 55.0 or less. Z calculated from this is 3300 or less. Geopolymer composition. 　 The average Blaine value (cm ２ / g) is 5000 cm ２ / g or more. 　 A hardened geopolymer obtained by hardening the geopolymer composition according to claim 1 or 2. 　 A method for producing a hardened geopolymer, comprising the step of kneading the geopolymer composition according to claim 1 or 2 and then hardening it. 　 The method for producing a hardened geopolymer body according to claim 4, wherein the hardening step includes air curing. 　 The method for producing a hardened geopolymer according to claim 5, wherein the hardened geopolymer is mortar or concrete.

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