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

Abstract

To provide a geopolymer composition capable of maintaining good flowability by a simple method even when using coal ash containing a large amount of unburned carbon as a raw material.SOLUTION: There is provided a geopolymer composition comprising an active filler, an aggregate, an activator, a polycondensate-based dispersant containing a polyalkylene glycol monophenyl ether as a partial structure and moisture, wherein the active filler comprises untreated coal ash and a blast furnace slag fine powder, the loss on ignition of the coal ash is 3.0% or more, the blending amount of the blast furnace slag fine powder is two times or more that of the coal ash, w / b (representing the percentage of (the blending amount of the moisture (mass%)) / (the blending amount of the total of the active filler (mass%))) of the geopolymer composition is 30 or more and 37 or less and the blending amount of silica fume based on the total mass of the active filler is less than 20 mass%.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Hardened materials such as concrete, mortar, artificial stone, and hardened building materials generally contain cement. However, cement emits a large amount of CO2 when fired. Therefore, cement-free methods for producing hardened materials such as concrete and mortar, which are environmentally friendly, have been attracting attention. In particular, methods for producing hardened materials using the geopolymer method have been 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 active fillers that can be used include natural products such as coal ash, kaolin, and clay, as well as silica fume and blast furnace slag. Of these active fillers, coal ash is often used in the production of hardened geopolymers because it allows for efficient reuse of industrial waste.

[0004] On the other hand, from the viewpoint of the ease of handling of geopolymer compositions at the manufacturing or construction site of hardened products, it is preferable that the geopolymer composition have good fluidity before hardening (see, for example, Patent Document 1). However, it is known that unburned carbon contained in coal ash adversely affects the fluidity of geopolymer compositions. Specifically, it is known that the higher the unburned carbon content in coal ash, the lower the fluidity of the geopolymer composition. For example, Patent Document 2 discloses a method for producing a geopolymer composition that includes a step of reducing the unburned carbon content of coal ash (specifically, fly ash). Specifically, Patent Document 2 describes a method for producing a geopolymer composition with high fluidity before hardening, which includes a fly ash production step in which a raw material containing unburned carbon is dispersed in water and the resulting slurry is subjected to flotation to produce fly ash with an unburned carbon content of 2% or less; a kneading step in which raw materials containing fly ash, ground granulated blast furnace slag, and an alkali silica solution are kneaded to produce a geopolymer mixture; and a curing step in which the geopolymer mixture is hardened. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-26357 [Patent Document 2] Japanese Patent Publication No. 2020-186143 Summary of the Invention [Problem to be solved by the invention]

[0006] However, according to the method described in Reference 2, when preparing a geopolymer composition using coal ash with a high unburned carbon content as a raw material, an additional step is required to reduce the unburned carbon content. This is therefore undesirable from the perspective of the cost and complexity of manufacturing hardened products using the geopolymer composition. Therefore, it would be advantageous to obtain a geopolymer composition with good fluidity before hardening without requiring an additional step, even if the coal ash used as a raw material has a high unburned carbon content.

[0007] For example, one possible solution to the problem of poor fluidity of geopolymer compositions due to unburned carbon in coal ash is to increase the amount of water contained in the geopolymer composition to improve fluidity. However, if the amount of water is too high, the strength of the hardened geopolymer composition after hardening may be insufficient, or bleeding (material separation) may occur. Therefore, it is difficult to solve the problem of poor fluidity of geopolymer compositions due to unburned carbon in coal ash simply by adjusting the amount of water.

[0008] Therefore, an object of the present invention is to provide a geopolymer composition that can maintain good fluidity using a simple method, even when coal ash containing a large amount of unburned carbon is used as a raw material. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. That is, the present invention includes the following preferred embodiments.

[0010] The geopolymer composition according to the first aspect of the present invention is a geopolymer composition comprising an active filler, an aggregate, an activator, a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure, and water, The active filler includes coal ash and ground granulated blast furnace slag that have not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015, The coal ash has an ignition loss of 3.0% or more, The amount of the ground granulated blast furnace slag mixed is at least twice the amount of the coal ash mixed, The w / b of the geopolymer composition (w / b represents the percentage of (the amount of water (mass%)) / (the total amount of active filler (mass%))) is 30 or more and 37 or less, The amount of silica fume mixed is less than 20% by mass based on the total mass of the active filler.

[0011] Alternatively, the geopolymer composition according to the second aspect of the present invention is a geopolymer composition comprising an active filler, an aggregate, an activator, a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure, and water, The active filler includes coal ash and ground granulated blast furnace slag, The coal ash has an ignition loss of 3.0% or more, The amount of the ground granulated blast furnace slag mixed is at least twice the amount of the coal ash mixed, The w / b of the geopolymer composition (w / b represents the percentage of (the amount of water (mass%)) / (the total amount of active filler (mass%))) is 30 or more and 37 or less, The amount of silica fume mixed is less than 20% by mass based on the total mass of the active filler.

[0012] A geopolymer composition according to a third aspect of the present invention is the geopolymer composition according to the first or second aspect, wherein the coal ash has an ignition loss of 8% or more.

[0013] A geopolymer composition according to a fourth aspect of the present invention is a geopolymer composition according to any one of the first to third aspects, wherein the amount of silica fume relative to the total mass of the active filler is 15 mass% or less.

[0014] A hardened geopolymer according to a fifth aspect of the present invention is obtained by hardening the geopolymer composition according to any one of the first to fourth aspects.

[0015] A method for producing a hardened geopolymer according to a sixth aspect of the present invention includes kneading a geopolymer composition according to any one of the first to fourth aspects, followed by curing.

[0016] A seventh aspect of the present invention relates to a method for producing a hardened geopolymer body, which is the method for producing a hardened geopolymer body according to the sixth aspect, wherein the curing is one or more of air curing and sealed curing.

[0017] A method for producing a hardened geopolymer material according to an eighth aspect of the present invention is the method for producing a hardened geopolymer material according to the sixth or seventh aspect, wherein the hardened geopolymer material is mortar or concrete. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a geopolymer composition that can maintain good fluidity using a simple method, even when coal ash containing a large amount of unburned carbon is used as a raw material. DETAILED DESCRIPTION OF THE INVENTION

[0019] The inventors conducted extensive research into geopolymer compositions that maintain good fluidity even when using coal ash containing a large amount of unburned carbon as a raw material. They focused on the ratio of ground granulated blast furnace slag to the amount of coal ash that has not been treated to comply with the JIS A 6201:2015 standard for fly ash for concrete (hereinafter referred to as "untreated coal ash"); the ratio of the total amount of water to the total amount of active filler (hereinafter referred to as "w / b percentage of the ratio of the total amount of water to the total amount of active filler" (i.e., w / b represents the percentage of (water amount (% by mass)) / (total amount of active filler (% by mass))); and the amount of silica fume.

[0020] As used herein, "water" refers to all water contained in the geopolymer composition, excluding solids. That is, the amount of "water" includes the amount of water contained in the aqueous solution of the activator, the amount of water contained in the aqueous solution of the dispersant, and any externally added water.

[0021] In this specification, unless otherwise specified, the terms "(total) active filler content (mass%)," "aggregate content (mass%)," "fine aggregate content (mass%)," "coarse aggregate content (mass%)," "activator content (mass%)," "dispersant content (mass%)," and "water content (mass%)" refer to the content (mass%) relative to the total mass of the geopolymer composition.

[0022] In this specification, "the amount (% by mass) of activator" means the amount (% by mass) of activator as a solid content, and "the amount (% by mass) of dispersant" means the amount (% by mass) of dispersant as a solid content. The amount (% by mass) of solids contained in the aqueous solution of activator or dispersant can be determined using a moisture analyzer, as described in the Examples below.

[0023] In this specification, the "loss on ignition (%) of coal ash (specifically, untreated coal ash)" can be calculated by conducting an ignition loss test in accordance with JIS A 6201:2015. The loss on ignition of coal ash is the amount that serves as a standard for the unburned carbon content in coal ash. For example, JIS A 6201:2015 specifies upper limits for the loss on ignition of fly ash types I to IV as quality standards according to the intended use of fly ash for concrete.

[0024] In this specification, the average Blaine value (cm) of coal ash (specifically, untreated coal ash) 2 / g)" means the average specific surface area of ​​coal ash. In detail, as will be described in the Examples below, "the average Blaine value (cm) of coal ash (specifically, untreated coal ash)" means the average specific surface area of ​​coal ash. 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.

[0025] 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.

[0026] 1. Geopolymer composition The geopolymer composition in this embodiment includes an active filler, an aggregate, an activator, a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure, and water. The active filler includes untreated coal ash and ground granulated blast furnace slag.

[0027] Furthermore, the geopolymer composition of this embodiment satisfies the following three conditions: (i) the amount of ground blast furnace slag is at least twice the amount of untreated coal ash, (ii) the percentage w / b of the ratio of the total amount of water to the total amount of active filler is 30 to 37, and (iii) the amount of silica fume is less than 20% by mass relative to the total mass of active filler. By having the geopolymer composition satisfy all three of these conditions, it is possible to obtain a geopolymer composition that can maintain good fluidity using a simple method, even when coal ash containing a large amount of unburned carbon is used as a raw material.

[0028] Below, the functions, amounts, etc. of each component contained in the geopolymer composition will be explained in detail.

[0029] 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 concrete composition (containing both fine and coarse aggregates as aggregates). However, the blending amount of each component described below can be adjusted as needed and used even when the geopolymer composition is used as a geopolymer mortar composition (containing only fine aggregates as aggregates).

[0030] <Active filler> The activated filler is a powder containing aluminosilicate as its main component. Aluminosilicate is active in 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.

[0031] In the geopolymer composition of this embodiment, the active filler is not particularly limited as long as it includes untreated coal ash and ground granulated blast furnace slag. For example, the active filler may include one or more of any active fillers known to those skilled in the art that have the above-mentioned functions, in addition to untreated coal ash and ground granulated blast furnace slag. The geopolymer composition of this embodiment may also include silica fume as an active filler, provided that the above-mentioned condition (iii) is satisfied: the amount of silica fume mixed relative to the total mass of the active filler is less than 20 mass%. These active fillers are described in detail below.

[0032] (coal ash) Coal ash contains silicon dioxide (SiO2), alumina (Al2O3), and the like as its main components. In this embodiment, the coal ash mainly includes untreated coal ash, i.e., coal ash that has not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015. In short, untreated coal ash refers to coal ash that has not been treated other than normal crushing for transportation from the production site, or raw powder coal ash. Using untreated coal ash as an activated filler allows for efficient and effective use of industrial by-product coal ash as a resource without processing. 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, and the like.

[0033] In this specification, "untreated coal ash" (or "coal ash that has not been treated to comply with the standard for fly ash for concrete specified in JIS A 6201:2015") is, in other words, coal ash that has not been subjected to crushing treatment and / or particle size adjustment (preferably particle size adjustment). Alternatively, for example, "untreated coal ash" is, in other words, coal ash that has not been subjected to crushing treatment and / or particle size adjustment (preferably particle size adjustment). 2 / g~6000cm 2The term "untreated coal ash" refers to coal ash that has a Blaine specific surface area of ​​about 1 / g and has not been subjected to pulverization and / or particle size adjustment (preferably particle size adjustment). Alternatively, for example, "untreated coal ash" refers to coal ash (untreated coal ash) that is preferably produced as an industrial by-product from at least one of a thermal power plant and a boiler. In one embodiment, the "untreated coal ash" may be untreated coal ash consisting solely of coal ash that does not comply with 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 complies with the standard.

[0034] Specifically, the untreated 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 untreated coal ash may be used in combination.

[0035] In the geopolymer composition of this embodiment, the loss on ignition of the untreated coal ash is 3.0% or more. Specifically, according to this embodiment, even when untreated coal ash having a loss on ignition of 3.0% or more and containing more unburned carbon than usual is used as a raw material, a geopolymer composition that can maintain good fluidity can be obtained by satisfying the three conditions (i) to (iii) described above.

[0036] The ignition loss of untreated coal ash is preferably 4.0% or more, more preferably 5.0% or more, even more preferably 6.0% or more, and particularly preferably a value selected from the group consisting of 7.0%, 8.0%, 9.0%, 10.0%, 11.0%, and 11.5% or more. The upper limit of the ignition loss of untreated coal ash is not particularly limited, but is, for example, about 30%.

[0037] The amount of untreated coal ash relative to the total mass of the active filler is adjusted appropriately to satisfy the above-mentioned condition (i) that the amount of ground granulated blast furnace slag is at least twice the amount of untreated coal ash. When the geopolymer composition satisfies the above-mentioned conditions (ii) and (iii), if the amount of ground granulated blast furnace slag is at least twice the amount of untreated coal ash, the effect of improving fluidity due to the ground granulated blast furnace slag described below can be obtained.

[0038] Specifically, the amount of untreated coal ash relative to the total mass of the activated filler is preferably 3% to 40% by mass. When the amount of untreated coal ash relative to the total mass of the activated filler is 3% by mass or more, untreated coal ash, an industrial by-product, can be effectively utilized as a resource, resulting in a geopolymer composition that is environmentally and cost-effective. Furthermore, when the amount of untreated coal ash relative to the total mass of the activated filler is 40% by mass or less, the amount of ground granulated blast furnace slag, which contributes to improving fluidity, is sufficient, ensuring a geopolymer composition that maintains good fluidity.

[0039] The amount of untreated coal ash relative to the total mass of coal ash in the activated filler is not particularly limited, but is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 100 mass%. That is, coal ash that has been treated to comply with the standard for fly ash for concrete specified in JIS A 6201:2015 may optionally be contained in the activated filler in an amount of, for example, 10 mass% or less, preferably 5 mass% or less, relative to the total mass of coal ash in the activated filler.

[0040] (ground granulated blast furnace slag) Ground granulated blast furnace slag contains calcium oxide (CaO), silicon dioxide (SiO2), alumina (Al2O3), etc. as its main components.

[0041] Any ground granulated blast furnace slag known to those skilled in the art can be used as the ground granulated blast furnace slag. 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. For example, commercially available ground granulated blast furnace slag that meets the JIS A 6206:2013 Ground Granulated Blast Furnace Slag 4000 standard can be used. Such commercially available ground granulated blast furnace slag includes, for example, "K-MENT" sold by Kobe Steel Slag Products Co., Ltd. and "ESMENT" manufactured by Nippon Steel Blast Furnace Cement Co., Ltd.

[0042] The amount of ground granulated blast furnace slag relative to the total mass of the active filler is adjusted appropriately to satisfy the aforementioned condition (i) that the amount of ground granulated blast furnace slag is at least twice the amount of untreated coal ash. When the geopolymer composition satisfies conditions (ii) and (iii), if the amount of ground granulated blast furnace slag is at least twice the amount of untreated coal ash, the large amount of ground granulated blast furnace slag can improve the fluidity of the geopolymer composition. This is presumably because the particle size of the ground granulated blast furnace slag commonly used in this technical field is finer than that of untreated coal ash. Specifically, when a large amount of ground granulated blast furnace slag is added, the particle size distribution of the entire active filler becomes broader, which is thought to improve the fluidity of the composition.

[0043] Specifically, the amount of ground granulated blast furnace slag relative to the total mass of the active filler is preferably 30% to 90% by mass. When the amount of ground granulated blast furnace slag is 30% by mass or more, the amount of ground granulated blast furnace slag that contributes to improving fluidity is sufficient, ensuring the production of a geopolymer composition that maintains good fluidity. Additionally, the greater the amount of ground granulated blast furnace slag, the easier it is to obtain a hardened body with the desired high strength in a shorter period of time. When the amount of ground granulated blast furnace slag is 90% by mass or less, the amount of untreated coal ash can be ensured, preventing a decrease in fluidity due to the incorporation of excessive ground granulated blast furnace slag.

[0044] The amount of ground granulated blast furnace slag relative to the total mass of the active filler is more preferably 40% by mass or more, and even more preferably 45% by mass or more, and more preferably 85% by mass or less, and even more preferably 80% by mass or less.

[0045] (Silica fume) Silica fume contains silicon dioxide (SiO2) as its main component. Specifically, silica fume is amorphous spherical fine particles of high-purity silicon dioxide (SiO2).

[0046] 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.

[0047] Silica fume is generally known to have the function of increasing the fluidity of geopolymer compositions. However, if the geopolymer composition satisfies the above-mentioned conditions (i) and (ii), the amount of silica fume must be kept below a certain value.

[0048] Specifically, as described above, the geopolymer composition of this embodiment satisfies the condition (iii) that the amount of silica fume blended is less than 20% by mass relative to the total mass of the active filler. When the geopolymer composition satisfies the conditions (i) and (ii) above, a decrease in the fluidity of the geopolymer composition due to excessive silica fume can be avoided by blending less than 20% by mass relative to the total mass of the active filler. Specifically, the particle size of silica fume is significantly finer than that of untreated coal ash and ground granulated blast furnace slag. Therefore, by reducing the amount of silica fume blended, it is expected that water absorption by the fine powder of excess silica fume can be prevented, thereby suppressing the decrease in fluidity of the geopolymer composition. Furthermore, because silica fume is expensive, reducing the amount of silica fume blended can also reduce the production cost of the geopolymer composition.

[0049] The amount of silica fume blended relative to the total mass of the active filler is preferably 18% by mass or less, more preferably 15% by mass or less, even more preferably 12% by mass or less, and particularly preferably 10% by mass or less. The lower limit of the amount of silica fume blended is not particularly limited. For example, the amount of silica fume blended relative to the total mass of the active filler may be 0% by mass.

[0050] (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.

[0051] The total amount (mass%) of active filler relative to the total mass of the geopolymer composition is adjusted appropriately so as to satisfy the condition (ii) above, that the ratio of the total amount of water to the total amount of active filler (w / b) is 30 or more and 37 or less.

[0052] When the geopolymer composition satisfies the above conditions (i) and (iii), if the ratio of the total amount of water to the total amount of active filler (w / b) is 37 or less, bleeding due to excessive water content and insufficient strength of the hardened geopolymer composition product can be avoided. From the viewpoint of more reliably avoiding bleeding and insufficient strength of the hardened product, the ratio of the total amount of water to the total amount of active filler (w / b) is preferably 36 or less, and more preferably 35 or less.

[0053] When the geopolymer composition satisfies the above conditions (i) and (iii), if the ratio of the total amount of water to the total amount of active filler (w / b) is 30 or more, a significant decrease in fluidity due to an extremely small amount of water can be prevented. From the viewpoint of more reliably avoiding a significant decrease in fluidity, the ratio of the total amount of water to the total amount of active filler (w / b) is preferably 30 or more, more preferably 31 or more, and even more preferably 32 or more.

[0054] The total mass (wt%) of active filler relative to the total mass of the geopolymer composition can be determined not only by the condition (ii) described above, but also by the ratio of the amount of activator solution in the geopolymer composition. Generally, the activator is used as a solid solution 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 solution, the ratio of the amount of activator solution to the total amount of active filler (i.e., activator solution (wt%) / active filler (total mass)) is preferably 4% to 30%. In this case, a ratio of activator solution (wt%) / active filler (total mass) of 4% or more can sufficiently promote the dehydration condensation reaction of the active filler, ultimately resulting in a hardened geopolymer with sufficient strength. Furthermore, a ratio of activator solution (wt%) / active filler (total mass) of 30% or less can prevent false setting due to an excessive amount of activator.

[0055] Likewise, in this case, the ratio of the activator aqueous solution (by weight) to the active filler (total weight) is preferably 10% or more, and more preferably 15% or more, and more preferably 25% or less, and even more preferably 20% or less.

[0056] The preferred ratio may vary depending on the type and concentration of the activator solution, but the ratio of activator solution (mass) to active filler (total mass) may be adjusted as needed to ensure that the active filler reacts sufficiently and does not cause false coagulation.

[0057] Furthermore, the total amount (mass %) of active filler relative to the total mass of the geopolymer composition varies depending on the type of hardened geopolymer, which is the final product. Therefore, the total amount of active filler can be adjusted appropriately depending on the type of hardened geopolymer desired. For example, the total amount of active filler relative to the total mass of the geopolymer composition is approximately 20% to 60% by mass. Examples of hardened geopolymers include concrete, mortar, etc., as mentioned above.

[0058] <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 concrete compositions containing fine aggregate and coarse aggregate, and geopolymer mortar compositions containing fine aggregate but not coarse aggregate.

[0059] 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 can be selected appropriately depending on the intended use of the final product, the hardened geopolymer. For example, two or more types of aggregate, such as a combination of fine and coarse aggregate, may be used.

[0060] Examples of fine aggregates include blast furnace slag fine aggregate and common natural aggregates such as silica sand. Of these, it is preferable to use blast furnace slag fine aggregate. Blast furnace slag fine aggregate has latent hydraulic properties. Latent hydraulic properties are the property of increasing the strength of the hardened product due to the formation of hydrates caused by silicon dioxide (SiO2), alumina (Al2O3), etc. contained in blast furnace slag fine aggregate. 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 body.

[0061] Blast furnace slag fine aggregate is specified in JIS A 5011-1:2018. Commercially available blast furnace slag fine aggregate may also 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.

[0062] It is also preferable to use blast furnace slag coarse aggregate, which is made from blast furnace slag. Using blast furnace slag coarse aggregate and / or the aforementioned blast furnace slag fine aggregate as aggregate allows for the effective use of industrial by-products as resources, resulting in a geopolymer composition that is highly environmentally friendly. Furthermore, manufacturing costs can be reduced.

[0063] The amount of aggregate to be mixed is not particularly limited and may 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 to be mixed is 30% by mass or more, separation between the aggregate and the geopolymer composition paste can be prevented, making it easier to form a uniform hardened body. When the amount of aggregate to be mixed is 70% by mass or less, bleeding can be easily suppressed.

[0064] The amount of aggregate mixed is preferably 40% by mass or more, and even more preferably 50% by mass or more, and more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, based on the total mass of the geopolymer composition.

[0065] <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 solution is an alkaline solution that comes into contact with the aluminosilicate in the activated filler and dissolves silicon and aluminum. Therefore, the activator as a solid reduces the fluidity of the geopolymer composition over time after mixing, from the perspective of causing a dehydration condensation reaction. On the other hand, when used in the form of an aqueous solution, the activator solution also contributes to improving the fluidity of the geopolymer composition immediately after mixing.

[0066] The activator aqueous solution is not particularly limited as long as it is a commonly used one, and for example, aqueous solutions 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.

[0067] The concentration of the alkaline aqueous solution, which is the aqueous solution of the activator, needs to 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 solution of the activator is 4 mol / L or more, the dehydration condensation reaction in the activated filler can be sufficiently induced. When the concentration of the aqueous solution of the activator is 12 mol / L or less, the generation of excessive heat of fusion due to high concentration can be avoided.

[0068] 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.

[0069] As mentioned above, when the activator as a solid content is made into an aqueous solution, the amount of water contained in the aqueous solution of the activator may be adjusted within an appropriate range so as to satisfy the above-mentioned condition (ii) that the ratio of the total amount of water to the total amount of active filler (w / b) is 30 or more and 37 or less.

[0070] At the same time, as mentioned above, the amount of the activator aqueous solution can also be determined from the ratio of the total amount of active filler to the total mass of the geopolymer composition.

[0071] <Moisture> As mentioned above, the term "water" encompasses all water contained in the geopolymer composition. In other words, in this specification, "water" refers to the water contained in the aqueous solution of the activator when the solid activator is dissolved in water; the water contained in the aqueous solution of the dispersant when the solid dispersant is dissolved in water; water added separately for purposes such as adjusting the fluidity of the geopolymer composition (hereinafter referred to as "externally added water"); and water contained in other optional materials. The type of water in this water is not particularly limited; examples include tap water and ion-exchanged water. The pH and temperature of the water are also optional and can be adjusted to general values ​​as appropriate depending on the type and amount of each component contained in the geopolymer composition.

[0072] 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 can lead to bleeding and insufficient strength of the hardened geopolymer composition product. However, the geopolymer composition of this embodiment contains a polycondensate-based dispersant having a polyalkylene glycol monophenyl ether as a partial structure, as described below, as a dispersant. Therefore, compared to general geopolymer compositions, the amount of water required to ensure good fluidity can be reduced.

[0073] The amount of water (mass%) relative to the total mass of the geopolymer composition is not particularly limited as long as the above-mentioned condition (ii) (w / b) (the percentage of the ratio of the total amount of water to the total amount of active filler) is 30 or more and 37 or less is met. For example, the amount of water may be adjusted within an appropriate range based on the amount of the total amount of active filler used as a raw material so as to satisfy the condition that w / b is 30 or more and 37 or less.

[0074] More specifically, the water content is preferably 6.0% to 10.0% by mass. The water content is more preferably 9.5% by mass or less, even more preferably 9.0% by mass or less, and particularly preferably 8.5% by mass or less. The water content is more preferably 6.5% by mass or more, even more preferably 7.0% by mass or more, and particularly preferably 7.5% by mass or more.

[0075] <Dispersant> The geopolymer composition in this embodiment contains a polycondensate-based dispersant having a polyalkylene glycol monophenyl ether as a partial structure. Specifically, this solid dispersant is often used as a polycondensate-based dispersant having a polyalkylene glycol monophenyl ether as a partial structure in the form of an aqueous solution.

[0076] 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.

[0077] In this specification, the term "polycondensate dispersant having a 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.

[0078] Structural unit A: At least one polyethylene glycol monophenyl ether represented by the following formula (1). [ka] [wherein, m is an integer of 3 to 280]

[0079] 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.

[0080] 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.

[0081] 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.

[0082] The solid content of the dispersant is preferably 0.05% to 0.25% by mass. When the solid content of the dispersant is 0.05% 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 0.25% by mass or less, separation and bleeding of the geopolymer composition due to the addition of excessive dispersant can be suppressed.

[0083] The solid content of the dispersant is more preferably 0.06% by mass or more, even more preferably 0.07% by mass or more, and particularly preferably 0.08% by mass or more, and more preferably 0.23% by mass or less, even more preferably 0.21% by mass or less, and particularly preferably 0.20% by mass or less.

[0084] <Other ingredients> The geopolymer composition of this embodiment may contain any material that can be commonly added as a raw material for mortar, concrete, etc., as long as it does not impair the effect of maintaining good fluidity. 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.

[0085] 2. Preparation method of 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, active filler (e.g., activated filler containing untreated coal ash, blast furnace slag powder, and silica fume) and aggregate (e.g., fine aggregate and coarse aggregate), are mixed in a predetermined blending ratio. In the subsequent kneading step, water and an activator and dispersant in aqueous solution are further added to the powder mixture in a predetermined blending ratio, 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.

[0086] In addition, in the method for preparing a geopolymer composition, a powder mixture can be prepared in advance by mixing the main powder raw materials, active filler (e.g., activated filler including untreated coal ash, blast furnace slag powder, and silica fume), aggregate (e.g., fine aggregate and coarse aggregate), activator, and dispersant in predetermined amounts, and the prepared powder mixture can 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 geopolymer composition. Alternatively, when the activator and / or dispersant are prepared in the form of an aqueous solution and used, a powder mixture can be prepared in advance by adding and mixing the active filler and aggregate, which are materials other than the activator aqueous solution and / or the dispersant aqueous solution, in predetermined amounts, and the prepared powder mixture can 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 are 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.

[0087] The geopolymer composition of this embodiment can maintain good fluidity using a simple method, even when coal ash containing a large amount of unburned carbon is used as a raw material. Maintaining good fluidity allows the geopolymer composition to be easily handled at the manufacturing site of the hardened product. Additionally, the geopolymer composition of this embodiment does not require an additional process to reduce the unburned carbon in untreated coal ash. A geopolymer composition that maintains good fluidity can be obtained simply by adjusting the blending amounts of each component in the geopolymer composition. Therefore, this is industrially very advantageous in terms of reducing the manufacturing costs of hardened geopolymer compositions.

[0088] 3. Hardened geopolymer and manufacturing method for hardened geopolymer The hardened geopolymer body in this embodiment is obtained by hardening the geopolymer composition in the above-described embodiment. The hardened geopolymer body has any shape that can be formed by any molding method, construction method, etc.

[0089] The hardened geopolymer material is preferably concrete or mortar, but is not particularly limited thereto. 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.

[0090] The method for producing a hardened geopolymer in this embodiment includes mixing and curing the geopolymer composition in the above-described embodiment. Specifically, the mixed 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. The molded or applied geopolymer composition is then cured using any curing method known to those skilled in the art. As a result, a hardened geopolymer can finally be obtained.

[0091] As a specific curing method, it is preferable that the curing be one or more of air curing and sealed curing. As described above, the geopolymer composition of this embodiment contains a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure as a dispersant, so the amount of water can be reduced compared to general geopolymer compositions. Therefore, without performing complex processes such as steam curing, which are expensive and have a large environmental impact, it is possible to produce a geopolymer hardened body with sufficient strength in a shorter time than usual by using, for example, air curing and sealed curing.

[0092] In order to obtain a high-strength hardened geopolymer body in a shorter period of time, curing may be performed by combining one or more of air curing and sealed curing with steam curing (preferably short-term steam curing).

[0093] 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.

[0094] 4. Geopolymer composition, hardened geopolymer body, and method for producing hardened geopolymer body according to another embodiment In the above embodiment, the active filler is described as containing untreated coal ash, but the active filler does not necessarily contain untreated coal ash. Specifically, the geopolymer composition according to another embodiment contains an active filler, an aggregate, an activator, a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure, and water, and the active filler may contain coal ash and blast furnace slag ground powder.

[0095] Furthermore, in another embodiment, the geopolymer composition satisfies the following three conditions: (i) the amount of blast furnace slag powder is at least twice the amount of coal ash, (ii) the ratio of the total amount of water to the total amount of active filler (w / b) is 30 or more and 37 or less, and (iii) the amount of silica fume is less than 20 mass% of the total mass of active filler.

[0096] In addition, in the geopolymer composition of this other embodiment, the coal ash has an ignition loss of 3.0% or more. Specifically, according to this other embodiment, even when coal ash having an ignition loss of 3.0% or more and containing more unburned carbon than usual is used as a raw material, by satisfying the three conditions (i) to (iii) described above, a geopolymer composition that can maintain good fluidity can be obtained, as in the previous embodiment.

[0097] The details of the geopolymer composition, the hardened geopolymer, and the method for manufacturing the hardened geopolymer in this other embodiment are the same as those of the above-mentioned embodiment, except that it is not essential that the active filler contain untreated coal ash. [Example]

[0098] 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.

[0099] In this example, we investigated the detailed relationship between the fluidity of a geopolymer composition containing unburned carbon in the raw coal ash and the amount of blast furnace slag powder mixed relative to the amount of coal ash, the ratio of the total amount of water to the total amount of active filler (w / b), and the amount of silica fume mixed. Specifically, we first prepared various geopolymer compositions by varying the amount of unburned carbon, coal ash, and water contained in the raw coal ash. We then conducted fluidity and bleeding tests on the geopolymer compositions to evaluate them.

[0100] In this example, the "ignition loss (%) of coal ash," which serves as a criterion for the unburned carbon content in coal ash, was calculated by conducting an ignition loss test in accordance with JIS A 6201:2015.

[0101] 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").

[0102] First, the raw materials of the geopolymer compositions used in each experimental example and each comparative example and their preparation methods will be described in detail below.

[0103] [Raw materials for geopolymer compositions] The raw materials of the geopolymer compositions used in each experimental example and each comparative example are as follows. Coal ash 1 (untreated coal ash (coal ash collected from thermal power plants as an industrial by-product, specifically fly ash captured by an electrostatic precipitator)): Loss on ignition 11.7%, average Blaine value 4670 cm 2 / g Coal ash 2 (untreated coal ash (coal ash collected from thermal power plants as an industrial by-product, specifically fly ash captured by an electrostatic precipitator)): Loss on ignition 4.0%, average Blaine value 4310 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: Pozzolith Solutions, "Mastercrete SF 5000", bulk density: 2.2 g / cm 3 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 nominal sieve size is 0.6 mm) Coarse aggregate (cooled blast furnace slag) (Example 2 only): Coarse blast furnace slag adjusted to a particle size of 5 mm to 20 mm Coarse aggregate (Examples other than Example 2 and each Comparative Example): Hard crushed sandstone from Omi (maximum size 20 mm, surface dry density 2.65 g / cm 3 ) ·Externally added water: tap water Activator solution: Pozzolith Solutions' Mastercrete AC 5025 Aqueous solution of dispersant: an 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 19.9 parts by weight of paraformaldehyde are added to a heatable reactor equipped with a stirrer and a metering pump. 1 part by weight is 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.

[0104] [Method for preparing geopolymer composition] The above raw materials were mixed in the respective amounts shown in Tables 1 and 2 below (Table 1 shows the blending amount (mass%) relative to the total mass of the composition, and Table 2 shows the blending amount (mass%) relative to the total mass of the active filler), to prepare the geopolymer compositions of Examples 1 to 7 and Comparative Examples 1 to 8. Specifically, first, coal ash 1 or coal ash 2, ground granulated blast furnace slag, and silica fume were mixed as the active filler in the respective blending amounts shown in Table 2 below. Next, fine aggregate or both fine and coarse aggregates were added as aggregate in the respective blending amounts shown in Table 1 to this mixed powder and mixed. Finally, an aqueous solution of the activator, an aqueous solution of the dispersant, and externally added water were added to the mixture and kneaded using a forced twin-shaft mixer. The blending amounts of the activator and dispersant are shown in Table 1 below as solids blend amounts (mass%). The blending amount of water is the total blending amount (mass%) of 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. Specifically, the amount of externally added water was adjusted and added so that the amount of water would be the amount shown in Table 1, based on the total amount (mass%) of water contained in the activator aqueous solution and the dispersant aqueous solution.

[0105] Table 1 below also shows the percentage (w / b) of the ratio of the total amount of water to the total amount of active filler. The amount of water (mass%) required to determine this w / b was calculated by adding the amount of externally added water (mass%), the amount of water (mass%) contained in the activator aqueous solution, and the amount of water (mass%) contained in the dispersant aqueous solution. The amount of water (mass%) contained in the activator aqueous solution or dispersant aqueous solution was determined by subtracting the solid content (mass%) of each solution from the amount (mass%) of the activator aqueous solution or dispersant aqueous solution. The solid content (mass%) was determined by evaporating each solution to dryness at 110°C for approximately 15 minutes using an A&D moisture analyzer (MX-50). Table 2 also shows the ratio of ground granulated blast furnace slag to the amount of coal ash.

[0106] [Table 1]

[0107] [Table 2]

[0108] Next, 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.

[0109] [Fluidity test of geopolymer composition] The fluidity of geopolymer compositions (geopolymer concrete compositions) 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 the 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. If the slump flow was 65 cm or greater and T50 was within 10 seconds, maintaining high fluidity, the fluidity of the geopolymer composition was rated "A" (good). If these measurement conditions were not met, the fluidity of the geopolymer composition was rated "B" (poor).

[0110] [Bleeding test of geopolymer composition] The bleeding test for the geopolymer composition was conducted as follows. After mixing the raw materials for the geopolymer composition to a total volume of 1.5 L, the mixed composition was left for one hour. After one hour had passed, the water floating on the surface of the left-standing composition was removed with a dropper. The volume of the removed water was then measured using a measuring cylinder, and the degree of bleeding was evaluated.

[0111] The results of the fluidity test and the bleeding test for the geopolymer compositions (geopolymer concrete compositions) of each experimental example and each comparative example are summarized in Table 3 below. The geopolymer compositions of Comparative Examples 1 and 2 were found to have bleeding in the first place, so their fluidity could not be measured.

[0112] [Table 3]

[0113] [Consideration] As shown in Table 3 above, the geopolymer compositions of Examples 1 to 7 maintained good fluidity regardless of whether the raw material used was coal ash with an ignition loss of 11.7% or 4.0%. This is thought to be because, as shown in Tables 1 and 2 above, the geopolymer compositions of Examples 1 to 7 satisfy all three of the above-mentioned conditions (i) to (iii).

[0114] On the other hand, as shown in Table 3 above, bleeding occurred in the geopolymer compositions of Comparative Examples 1 and 2. This is thought to be largely due to the fact that although the geopolymer compositions of Comparative Examples 1 and 2 satisfy the conditions (i) and (iii) described above, the amount of water blended is large, and the ratio of the total amount of water to the total amount of active filler (w / b) exceeds 37.

[0115] As shown in Table 3 above, the geopolymer compositions of Comparative Examples 3, 4, and 6 did not exhibit good fluidity. This is because, although the geopolymer compositions of Comparative Examples 3, 4, and 6 met the conditions (ii) and (iii) described above, the amount of ground blast furnace slag mixed relative to the amount of coal ash mixed was small, which is presumed to have had a negative effect on the fluidity of the composition.

[0116] As shown in Table 3 above, the fluidity of the geopolymer compositions of Comparative Examples 5 and 7 was significantly reduced. This is because, although the geopolymer compositions of Comparative Examples 5 and 7 met the above-mentioned conditions (i) and (ii), the amount of silica fume blended was significantly high, which is presumed to have had a significant adverse effect on the fluidity of the composition.

[0117] As shown in Table 3 above, the geopolymer composition of Comparative Example 8 did not exhibit good fluidity. This is because, although the geopolymer composition of Comparative Example 8 met the conditions (i) and (iii) described above, the amount of water blended was low, and the ratio of the total amount of water to the total amount of active filler (w / b) was less than 30, which is presumably a significant adverse effect on the fluidity of the composition.

[0118] From the above results, it can be seen that regardless of the quality of the coal ash in terms of loss on ignition (content of unburned carbon), good fluidity of the geopolymer composition can be maintained by adjusting the ratio of the amount of ground blast furnace slag to the amount of untreated coal ash, the percentage ratio of the total amount of water to the total amount of active filler (w / b), and the silica fume to the total mass of active filler to appropriate values.

Claims

1. A geopolymer composition comprising an active filler, an aggregate, an activator, a polycondensate dispersant having a polyalkylene glycol monophenyl ether as a partial structure, and water, The active filler includes coal ash and ground granulated blast furnace slag that have not been treated to conform to the standard for fly ash for concrete specified in JIS A 6201:2015, The coal ash has an ignition loss of 3.0% or more, The amount of the ground granulated blast furnace slag mixed is at least twice the amount of the coal ash mixed, The w / b of the geopolymer composition (w / b represents the percentage of (the amount of water (mass%)) / (the total amount of active filler (mass%))) is 30 to 37, and The geopolymer composition, wherein the amount of silica fume is less than 20% by weight based on the total weight of the active filler.

2. 2. The geopolymer composition of claim 1, wherein the coal ash has a loss on ignition of 8% or more.

3. The geopolymer composition of claim 1, wherein the amount of silica fume relative to the total mass of the active filler is 15% by mass or less.

4. A hardened geopolymer obtained by hardening the geopolymer composition according to any one of claims 1 to 3.

5. A method for producing a hardened geopolymer, comprising kneading the geopolymer composition according to any one of claims 1 to 3 and then curing it.

6. 6. The method for producing a hardened geopolymer body according to claim 5, wherein the curing is one or more of air curing and sealed curing.

7. The method for producing a hardened geopolymer according to claim 5, wherein the hardened geopolymer is mortar or concrete.

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