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

Abstract

Provided is a geopolymer composition which is capable of suppressing the amount of silica fume blended, and which is capable of achieving both good fluidity over a long period of time and high strength of a cured body in a short period of time by a simple method. The geopolymer composition contains: an active filler; aggregate; an activator; a dispersant; the present invention relates to a geopolymer composition containing silica fume and added water, the geopolymer composition containing no silica fume or containing less than 1% by mass of silica fume with respect to the total mass of the geopolymer composition, the total water content of the geopolymer composition being 10-13% by mass, and the content of silica fume being less than 1% by mass with respect to the total mass of the geopolymer composition. The active filler includes: a blast furnace slag fine powder in an amount of 35% by mass or more relative to the total mass of the active filler; and coal ash, and the dispersant is a polycondensate dispersant containing a polyalkylene glycol monophenyl ether as a partial structure.

Description

Technical Field

[0001] The present invention relates to a geopolymer composition, a cured product thereof, namely a geopolymer cured body, and a method for producing the geopolymer cured body. Background Art

[0002] Solidified materials such as concrete, mortar, artificial stone, and solidified building materials typically contain cement. However, cement emits large amounts of CO2 during firing. Consequently, methods for producing solidified materials such as concrete without cement and from an environmental perspective are attracting attention. In particular, methods for producing solidified materials using the geopolymer method are being widely researched.

[0003] In the geopolymer method, powders primarily composed of silicon or aluminum are used as a binder to bond the powders together to create artificial rock. The geopolymer solidified body formed using the geopolymer method is produced by using an active filler (aluminosilicate source) and an alkaline aqueous solution (activator) to induce a geopolymerization reaction. Active fillers include natural materials such as kaolin and clay, fly ash, silica fume, blast furnace slag, and rice husk ash. Alkaline aqueous solutions include aqueous solutions of sodium hydroxide and water glass (sodium silicate).

[0004] The primary function of active fillers is to form a geopolymer solid body and increase its strength. Among active fillers, silica fume not only significantly contributes to the short-term strength improvement of the polymer solid body but also imparts long-term fluidity to the geopolymer composition immediately after kneading. Therefore, silica fume is widely used in the production of geopolymer solid bodies due to its high workability. For example, Patent Document 1 describes a geopolymer composition comprising: blast furnace slag powder and fly ash as powder raw materials; fine aggregate; silica fume; potassium hydroxide or sodium hydroxide as an alkali source; and water. The volume ratio of the blast furnace slag powder to the powder raw materials, BFS / P, is 35-80%, the molar ratio of silicon contained in the silica fume to the alkali source, Si / A, is 0.05-0.35, and the molar ratio of the alkali source to water, A / W, is 0.1-0.3.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-066613 Summary of the Invention

[0008] The present invention aims to provide a geopolymer composition that can reduce the amount of silica fume mixed and can achieve both good fluidity for a long time and high strength of the cured product in a short time using a simple method.

[0009] The present inventors have conducted intensive research to solve the above-mentioned problems and have completed the present invention. Specifically, the present invention includes the following preferred technical solutions.

[0010] The first aspect of the present invention relates to a geopolymer composition comprising: an active filler; an aggregate; an activator; a dispersant; and added water, wherein:

[0011] The geopolymer composition does not contain silica fume, or contains less than 1% by mass of silica fume relative to the total mass of the geopolymer composition.

[0012] The total moisture content of the geopolymer composition is 10% to 13% by mass.

[0013] The active filler comprises: 35% by mass or more of blast furnace slag fine powder relative to the total mass of the active filler; and coal ash, and

[0014] The dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure.

[0015] The second aspect of the present invention relates to a geopolymer solidified body, which is a solidified product of the geopolymer composition according to the first aspect.

[0016] The third aspect of the present invention relates to a method for producing a geopolymer solidified body, comprising the steps of mixing and kneading the geopolymer composition according to the first aspect, and then solidifying the geopolymer composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a graph showing the results of fluidity tests on geopolymer compositions of Examples.

[0018] Figure 2 This is a graph showing the results of uniaxial compressive strength tests on cured products of geopolymer compositions according to Examples. DETAILED DESCRIPTION

[0019] Silica fume is included as an active filler in most geopolymer compositions currently manufactured and developed. The geopolymer composition described in Patent Document 1 also contains silica fume as an essential active filler component. However, compared to other active fillers, silica fume has a higher material cost. Therefore, silica fume contributes to the high cost of producing a solidified geopolymer composition.

[0020] When the geopolymer composition does not contain any silica fume or contains only a small amount of silica fume, the fluidity of the geopolymer composition immediately after kneading is low, and it is also difficult to obtain a solidified body having a desired strength in a short period of time.

[0021] If the fluidity of the geopolymer composition immediately after kneading is low, the workability of the geopolymer composition at the manufacturing site of the solidified product will deteriorate. To compensate for the low fluidity of such geopolymer compositions, one approach is to increase the amount of water contained in the activator; or, alternatively, to increase the amount of water added when adding water. However, if the total water content in the geopolymer composition increases, problems such as the need for long-term curing to achieve the strength of the solidified product, bleeding of the composition or solidified product, or insufficient strength of the solidified product produced may occur. Alternatively, to achieve the desired strength in a short period of time, one approach is to replace conventional curing, such as in water, in a humid environment, or in air, with steam curing. However, because steam curing is expensive, manufacturing costs can significantly increase.

[0022] As described above, if the amount of silica fume incorporated into a geopolymer composition is reduced in order to reduce production costs, various problems may arise from the viewpoints of both the fluidity of the composition immediately after kneading and the strength of the cured product.

[0023] The present inventors have conducted extensive research on geopolymer compositions that maintain high fluidity over a long period of time while reducing the amount of silica fume incorporated, and that produce a high-strength solidified body in a short period of time using a simple method. Furthermore, the present invention was achieved by focusing on the type and amount of active fillers contained in the geopolymer composition, the type of dispersant, and the total moisture content of the geopolymer composition.

[0024] According to the present invention, a geopolymer composition can be provided which can reduce the amount of silica fume blended and achieve both good fluidity for a long time and high strength of a cured product in a short time by a simple method.

[0025] Specifically, the geopolymer composition of this embodiment contains an active filler, aggregate, an activator, a dispersant, and added water. The geopolymer composition does not contain silica fume, or contains less than 1% by mass of silica fume relative to the total mass of the geopolymer composition. The dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure. By including this specific type of dispersant in the geopolymer composition, the total amount of water in the geopolymer composition required to ensure high fluidity over a long period of time can be reduced, even when the silica fume content is 0% by mass or less than 1% by mass.

[0026] Furthermore, the geopolymer composition of this embodiment contains blast furnace slag fine powder as an active filler, accounting for 35% or more by mass relative to the total mass of the active filler. As will be described in detail below, blast furnace slag fine powder contributes significantly to the strength of the solidified product compared to other active fillers other than silica fume. Therefore, by including a large amount of blast furnace slag fine powder, a high-strength solidified product can be obtained in a short period of time through standard curing, even without complex treatments such as steam curing. In other words, the geopolymer composition of this embodiment incorporates a specific type of dispersant, and the amount of blast furnace slag fine powder as an active filler and the total moisture content of the composition are appropriately adjusted. As a result, even while reducing the amount of silica fume, which contributes to high costs, the fluidity of the kneaded composition and the strength of the solidified product can be maintained. Furthermore, fly ash is included as an active filler. The fly ash can be those that have undergone a special pretreatment to achieve uniform quality (specifically, treatment that complies with the fly ash standards for concrete specified in JIS A 6201:2015). However, even when coal ash that has not been subjected to this special pretreatment is used as coal ash, the effects of the geopolymer composition according to this embodiment can be obtained.

[0027] In this specification, "water" refers to all water contained in the geopolymer composition of this embodiment, including water contained in the activator, water contained in the dispersant, any added water, and any water contained in other materials. Furthermore, in this specification, "total moisture content" (mass %) refers to the total amount (mass %) of these "water" in the geopolymer composition of this embodiment. As described in the Examples below, this "total moisture content" (mass %) can be calculated by using a moisture analyzer to determine the total solid content (mass %) of components containing water and subtracting this value from the total solution content (mass %).

[0028] In this specification, "added water" refers to water added arbitrarily, excluding water contained in the activator, water contained in the dispersant, and water contained in any other materials. Specifically, the added water is added to the geopolymer composition of this embodiment for purposes such as adjusting the fluidity of the geopolymer composition and promoting the migration of various ions involved in the geopolymer reaction. Examples of the added water include, but are not limited to, tap water and ion-exchanged water.

[0029] Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention.

[0030] 1. Geopolymer composition

[0031] The geopolymer composition of this embodiment contains active filler, aggregate, activator, dispersant and added water. The dispersant is a polycondensate dispersant containing polyalkylene glycol monophenyl ether as a partial structure.

[0032] In this embodiment, the aggregate contained in the geopolymer composition includes fine aggregate and / or coarse aggregate. That is, the geopolymer composition of this embodiment can be applied to both geopolymer mortar compositions containing fine aggregate but no coarse aggregate and geopolymer concrete compositions containing both fine aggregate and coarse aggregate.

[0033] Below, the function of each component and its mixing amount, the total moisture content of geopolymer composition and the preparation method of geopolymer composition are described in detail. It should be noted that the mixing amount and the mix ratio of each component of the geopolymer composition recorded below, as long as there is no special record, mainly refer to: the mixing amount and the mix ratio when the geopolymer composition is applied to the geopolymer mortar composition. However, even when the geopolymer composition is applied to the geopolymer concrete composition, the mixing amount and the mix ratio of these components can also be appropriately adjusted and adopted as required.

[0034] Active fillers

[0035] Active fillers are powders primarily composed of aluminosilicates. Aluminosilicates are alkali-active. Adding an activator (described below) or water to the active filler partially dissolves or ionizes the silicon and / or aluminum in the active filler. The dissolved silica, present in a near-monomer state in the alkali silica solution, absorbs metal ions. This results in a dehydration-condensation reaction, forming a solidified polymer compound (polymer). This solidified polymer compound becomes the solidified product of the geopolymer composition.

[0036] In the geopolymer composition of this embodiment, the active filler is not particularly limited, as long as it contains blast furnace slag fine powder and fly ash in an amount of 35% by mass or more relative to the total mass of the active filler. The type of fly ash is not particularly limited; either untreated or treated to meet the standards for fly ash for concrete specified in JIS A 6201:2015 can be used. For example, the active filler may include, in addition to blast furnace slag fine powder and fly ash, one or more other active fillers known to those skilled in the art that have the aforementioned functions. The geopolymer composition of this embodiment may also contain silica fume as an active filler, but its amount relative to the total mass of the geopolymer composition is less than 1% by mass. These active fillers are described in detail below.

[0037] (coal ash)

[0038] Fly ash contains silicon dioxide (SiO2), aluminum oxide (Al2O3), and the like as main components. As described above, in this embodiment, the type of fly ash is not particularly limited. Specifically, the fly ash may include fly ash produced as an industrial by-product that has not been treated to comply with the fly ash standards for concrete specified in JIS A 6201:2015 (hereinafter sometimes referred to as "untreated fly ash"), may also include fly ash that has been treated in accordance with such treatment, or may be a mixture of such fly ash. Preferably, the fly ash includes untreated fly ash. Untreated fly ash refers to fly ash that has not been treated other than "conventional pulverization for the purpose of transporting from the source," or raw fly ash. If untreated fly ash is used as an active filler, the industrial by-product fly ash can be efficiently utilized as a resource in its untreated state. Furthermore, manufacturing costs can be reduced. This untreated fly ash can be obtained, for example, from thermal power plants, boilers, and the like as an industrial by-product generated during coal combustion.

[0039] In this specification, "fly ash that has not been treated to meet the standards for fly ash for concrete specified in JIS A 6201: 2015" means fly ash that has not been subjected to pulverization and / or particle size adjustment (preferably particle size adjustment). Alternatively, for example, "fly ash that has not been treated to meet the standards for fly ash for concrete specified in JIS A 6201: 2015" means fly ash with a particle size of 2900 cm 2 / g~6000cm 2 / g of Blaine specific surface area and has not been subjected to pulverization and / or particle size adjustment (preferably particle size adjustment). Alternatively, for example, "fly ash that has not been treated to meet the standards for fly ash for concrete specified in JIS A 6201:2015"—in other words, preferably, fly ash produced as an industrial by-product from at least one of thermal power plants and boilers (untreated fly ash). It should be noted that, in one embodiment, "fly ash that has not been treated to meet the standards for fly ash for concrete specified in JIS A 6201:2015" may be fly ash that does not meet the standards for fly ash for concrete specified in JIS A 6201:2015, or may include fly ash that does not meet these standards.

[0040] Specifically, coal ash, preferably untreated coal ash, includes fly ash captured from exhaust gas by a dust collector, bottom ash obtained by crushing ash cakes at the bottom of a boiler, etc. Coal ash, preferably untreated coal ash, may be used in combination of two or more types.

[0041] The geopolymer composition according to this embodiment can achieve the effects of exhibiting excellent and high fluidity over a long period of time, while also exhibiting high strength in the cured product within a short period of time. In particular, the same effects can be achieved even when untreated fly ash is included as an active filler. In other words, the aforementioned effects can be achieved even when the fly ash used is uneven in size, composition, etc., and its quality varies to a certain extent.

[0042] The amount of fly ash relative to the total mass of the active filler is not particularly limited as long as it meets the conditions for the amount of blast furnace slag fine powder described below. For example, the amount of fly ash relative to the total mass of the active filler is preferably 3% to 65% by mass. In the case where the fly ash includes untreated fly ash, the amount of untreated fly ash relative to the total mass of the active filler is also preferably 3% to 65% by mass. If the amount of untreated fly ash is 3% or more by mass, the untreated fly ash generated as an industrial by-product can be effectively utilized as a resource, and a geopolymer composition suitable from both an environmental and cost perspective can be obtained. In addition, if the amount of untreated fly ash is 65% or less by mass, the amount of blast furnace slag fine powder will not be insufficient, so the desired high-strength solidified body can be obtained in a short period of time.

[0043] The blending amount of fly ash relative to the total mass of the active filler is more preferably 23% by mass or greater, and even more preferably 50% by mass or greater. Furthermore, if the fly ash includes untreated fly ash, the blending amount of untreated fly ash relative to the total mass of the active filler is also more preferably 23% by mass or greater, and even more preferably 50% by mass or greater. It should be noted that if the fly ash used as the active filler includes both untreated fly ash and fly ash that has been treated in accordance with the standards for fly ash for concrete as defined in JIS A 6201:2015, the content of the treated fly ash relative to the total mass of the active filler is preferably, for example, approximately 5% by mass.

[0044] (Blast furnace slag fine powder)

[0045] Blast furnace slag fine powder contains calcium oxide (CaO), silicon dioxide (SiO2), aluminum oxide (Al2O3) and the like as main components.

[0046] Any blast furnace slag fine powder known to those skilled in the art can be used as the blast furnace slag fine powder. For example, the blast furnace slag fine powder can be obtained by finely grinding granulated blast furnace slag. Granulated blast furnace slag is obtained as a by-product when iron is refined in a blast furnace. In addition, commercially available blast furnace slag fine powder can be used. As a commercially available blast furnace slag fine powder, for example, blast furnace slag fine powder that meets the blast furnace slag fine powder 4000 standard of JIS A 6206 can be used. Such commercially available blast furnace slag fine powders include, for example, "Keiment" sold by Kobe Steel Slag Products Co., Ltd. and "Esment" manufactured by Nippon Steel Blast Furnace Cement Co., Ltd.

[0047] In the geopolymer composition of this embodiment, the blast furnace slag fine powder is incorporated in an amount of 35% by mass or greater relative to the total mass of the active filler. By increasing the blast furnace slag fine powder to 35% by mass or greater, the effect on the strength of the solidified body caused by suppressing the amount of silica fume incorporated can be compensated. As a result, even with a simple method, high strength of the solidified body can be achieved in a short period of time. Furthermore, industrial byproducts can be effectively utilized, resulting in a geopolymer composition suitable from both an environmental and cost perspective.

[0048] The blending amount of the blast furnace slag fine powder relative to the total mass of the active filler is preferably 36% by mass or more, more preferably 37% by mass or more.

[0049] The present inventors have confirmed that increasing the ratio of blast furnace slag fine powder to the total active filler content further improves the strength of the solidified body compared to increasing the ratio of other active fillers, such as coal ash (preferably untreated coal ash). Their experiments indicate that this is not due to differences in the structure of the resulting solidified body. More specifically, the present inventors used geopolymer compositions with varying ratios of coal ash (preferably untreated coal ash) and blast furnace slag fine powder and compared the Si atom perimeter structures of solidified bodies containing higher amounts of blast furnace slag fine powder and higher amounts of coal ash (preferably untreated coal ash) using NMR analysis. The results showed no difference in spectral peak position or peak width. On the other hand, the peak intensity of the spectrum was higher in the solidified body containing higher amounts of blast furnace slag fine powder. Therefore, it was determined that varying the ratio of coal ash to blast furnace slag fine powder produces solidified bodies with similar structures, but with different amounts of the resulting products.

[0050] Based on these results, it is predicted that blast furnace slag fine powder has a greater impact on the strength of the solidified body because it is more reactive than other active fillers such as coal ash (preferably untreated coal ash). This prediction can be inferred, for example, based on the vitrification rate, which can be used as a reactivity indicator. Specifically, the vitrification rate of commonly used blast furnace slag fine powder is 99%, while the vitrification rate of coal ash (preferably untreated coal ash) is approximately 70% to 80%. Therefore, the vitrification rate of the blast furnace slag fine powder contained in the geopolymer composition of this embodiment is preferably 99% or higher, and the vitrification rate of the coal ash (preferably untreated coal ash) is preferably 70% to 80%.

[0051] There is no particular upper limit on the amount of blast furnace slag fine powder added relative to the total mass of the active filler. For example, the amount of blast furnace slag fine powder added can be 100%. The amount of blast furnace slag fine powder added relative to the total mass of the active filler is preferably 77% by mass or less, more preferably 50% by mass or less. By setting the amount of blast furnace slag fine powder added to 77% by mass or less, excessive early strengthening of the geopolymer composition can be prevented.

[0052] (Silica fume)

[0053] Silica fume contains silicon dioxide (SiO2) as a main component. Specifically, silica fume is amorphous spherical fine particles of high-purity silicon dioxide (SiO2).

[0054] Any silica fume known to those skilled in the art can be used as the silica fume. For example, silica fume can be obtained as a byproduct from collecting dust from exhaust gases generated during the production of ferrosilicon, metallic silicon, electrolytic zirconia, etc. Alternatively, commercially available silica fume can be used.

[0055] Silica fume not only functions as a conventional active filler, i.e., serves as the starting point for dehydration and polycondensation reactions, thereby increasing the strength of the solidified product, but also improves the fluidity of the prepared geopolymer composition. This is due to its spherical shape.

[0056] The geopolymer composition of this embodiment does not contain silica fume, or only contains less than 1% by mass of silica fume relative to the total mass of the geopolymer composition. By setting the amount of silica fume to less than 1% by mass, the manufacturing cost of the geopolymer composition can be suppressed. In addition, according to the geopolymer composition of this embodiment, on the one hand, the amount of silica fume can be reduced, and on the other hand, more industrial by-products such as blast furnace slag powder (and untreated coal ash) can be effectively utilized as substitutes. Therefore, a geopolymer composition suitable for both environmental protection and cost can be obtained.

[0057] The amount of silica fume blended relative to the total mass of the geopolymer composition is preferably 0.5% by mass or less, more preferably 0.1% by mass or less. In particular, the geopolymer composition of this embodiment preferably does not contain silica fume.

[0058] (Other active fillers)

[0059] Examples of other active fillers that may be contained in the geopolymer composition of the present embodiment include red mud, feldspars, micas, zeolites, perlite, clay minerals, kaolin, metakaolin, and sewage sludge.

[0060] The total amount (mass %) of active fillers in the geopolymer composition can be determined based on the ratio to the amount of activator in the geopolymer composition. Specifically, when using an alkaline aqueous solution of approximately 8 to 10 mol / L as the activator, the ratio of activator to active filler (i.e., activator (mass) / active filler (total mass)) is preferably 5% to 30%. In this case, if the ratio of activator (mass) / active filler (total mass) is 5% or more, the dehydration condensation reaction of the active filler can be fully initiated, ultimately producing a geopolymer solidified body with sufficient strength. Furthermore, if the ratio of activator (mass) / active filler (total mass) is 30% or less, false setting caused by excessive activator can be prevented.

[0061] Likewise, in this case, the ratio of activator (mass) to active filler (total mass) is more preferably 10% or more, and even more preferably 15% or more. Furthermore, in this case, the ratio of activator (mass) to active filler (total mass) is more preferably 25% or less, and even more preferably 20% or less.

[0062] The above-mentioned preferred ratio may vary slightly depending on the type and concentration of the activator, but the activator (mass) / active filler (total mass) can be appropriately adjusted within the range where the active filler reacts sufficiently and false coagulation does not occur.

[0063] Furthermore, the total amount (mass %) of active fillers relative to the total mass of the geopolymer composition will vary depending on the type of geopolymer solidified product to be manufactured. Therefore, the total amount of active fillers can be appropriately adjusted based on the desired type of geopolymer solidified product. For example, the total amount of active fillers relative to the total mass of the geopolymer composition is approximately 20% to 60% by mass. Examples of geopolymer solidified products include mortars and concretes, as described above.

[0064] Aggregates

[0065] Any aggregate known to those skilled in the art can be used as the aggregate. For example, generally known aggregates used in the production of concrete, mortar, artificial stone, etc. can be used.

[0066] Aggregates may be either coarse aggregate or fine aggregate. Coarse aggregate is defined as aggregates in which at least 85% of the coarse aggregate is 5 mm or larger in diameter. Fine aggregate is defined as aggregates in which at least 85% of the fine aggregate is 5 mm or smaller in diameter. The type of aggregate may be appropriately selected based on the intended use of the geopolymer solidified product. For example, a combination of coarse aggregate and fine aggregate may be used.

[0067] Examples of fine aggregate include blast furnace slag fine aggregate and conventional natural aggregates such as silica sand. Among these, blast furnace slag fine aggregate is preferred. Blast furnace slag fine aggregate has latent hydraulic properties. Latent hydraulic properties refer to the property of forming hydrates based on silica (SiO2), alumina (Al2O3), and other substances contained in blast furnace slag fine aggregate, thereby increasing the strength of the solidified product. Therefore, using blast furnace slag fine aggregate as an aggregate can further improve the long-term strength of the geopolymer solidified body, the final product.

[0068] Blast furnace slag fine aggregate is defined in JIS A 5011-1:2018. Commercially available blast furnace slag fine aggregate can be used. Examples of commercially available blast furnace slag fine aggregate include "Shinkosand" sold by Kobelco Slag Products Co., Ltd. and blast furnace slag fine aggregate manufactured by JIFILM Co., Ltd.

[0069] As the coarse aggregate, blast furnace slag coarse aggregate made from blast furnace slag is also preferably used. Using blast furnace slag coarse aggregate and / or the aforementioned blast furnace slag fine aggregate as aggregate allows for efficient resource utilization of industrial byproducts, resulting in a geopolymer composition with high environmental adaptability. Furthermore, manufacturing costs can be reduced.

[0070] The amount of aggregate (preferably fine aggregate) added to the total mass of the geopolymer composition is not particularly limited and can be adjusted according to the desired use of the geopolymer solidified body as the final product. For example, the amount of aggregate (preferably fine aggregate) added to the total mass of the geopolymer composition is preferably 30% to 70% by mass. If the amount of aggregate (preferably fine aggregate) added is 30% by mass or more, separation of the aggregate and the geopolymer composition slurry can be prevented, and a uniform solidified body can be easily formed. If the amount of aggregate (preferably fine aggregate) added is 70% by mass or less, the good fluidity of the geopolymer composition can be easily maintained for a long time.

[0071] The amount of aggregate (preferably fine aggregate) blended relative to the total mass of the geopolymer composition is more preferably 40% by mass or more, and even more preferably 50% by mass or more. Furthermore, the amount of aggregate (preferably fine aggregate) blended relative to the total mass of the geopolymer composition is more preferably 65% by mass or less, and even more preferably 60% by mass or less.

[0072] <Add water>

[0073] The type of water to be added is not particularly limited, and examples thereof include tap water, ion-exchanged water, etc. Furthermore, the pH and temperature of the water to be added are also arbitrary and can be appropriately adjusted to conventional values according to the types and amounts of the components contained in the geopolymer composition.

[0074] Adding water helps improve the fluidity of the geopolymer composition. The geopolymer composition of this embodiment contains a specific type of dispersant that significantly improves the fluidity of the composition, which will be described later. Therefore, the amount of water added can also be extremely small.

[0075] On the other hand, in the geopolymer composition of this embodiment, the amount of silica fume incorporated is suppressed, so as described in detail below, the total moisture content needs to be adjusted to 10% to 13% by mass. Therefore, the amount of added water relative to the total mass of the geopolymer composition needs to be appropriately adjusted based on the amount (mass %) of water contained in the activator and the amount (mass %) of water contained in the dispersant, so that the total moisture content falls within the range of 10% to 13% by mass. Specifically, the amount of added water relative to the total mass of the geopolymer composition is preferably 4.5% or more, more preferably 5% or more, and even more preferably 6% or more. Furthermore, the amount of added water is preferably 7.8% or less, more preferably 7.6% or less, and even more preferably 7.3% or less.

[0076] Activator

[0077] The activator is a component that serves as the starting point for polymerization through the dehydration condensation reaction of the active filler. Specifically, the activator is an alkaline aqueous solution that contacts the aluminosilicate in the active filler and dissolves the silicon and aluminum. The activator is not particularly limited as long as it is a commonly used activator. For example, aqueous solutions of sodium hydroxide, water glass (sodium silicate), potassium silicate, etc. can be used. In addition, commercially available activators containing an alkali source can be used as the activator. Examples of such commercially available activators include the MasterCrete AC series manufactured by Pozzolith Solutions.

[0078] The concentration of the aqueous alkaline solution serving as the activator should be adjusted appropriately depending on its type and amount, and is preferably between 6 mol / L and 12 mol / L, for example. An activator concentration of 6 mol / L or greater allows for sufficient dehydration and condensation of the active filler. An activator concentration of 12 mol / L or less avoids excessive heat of fusion due to high concentrations.

[0079] The concentration of the aqueous alkaline solution as an activator needs to be appropriately adjusted depending on its type and the amount thereof, but is more preferably 7 mol / L or higher, and even more preferably 8 mol / L or higher. Furthermore, the concentration of the aqueous alkaline solution as an activator needs to be appropriately adjusted depending on its type and the amount thereof, but is more preferably 11 mol / L or lower, and even more preferably 10 mol / L or lower.

[0080] The amount (mass %) of the activator to be added relative to the total mass of the geopolymer composition can be determined in the same manner as described above, based on the ratio to the total amount (mass %) of the active filler in the geopolymer composition.

[0081] In this case, the amount (mass %) of water contained in the activator can also be appropriately adjusted according to the amount (mass %) of added water and the amount (mass %) of water contained in the dispersant so that the total water content is within the range of 10% to 13% by mass.

[0082] Dispersants

[0083] The geopolymer composition of this embodiment contains a polycondensation-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure. Specifically, the dispersant is a polycondensation-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure in an aqueous solution (in this specification, even in the aqueous solution state, it is simply referred to as "dispersant").

[0084] By including this dispersant in a geopolymer composition, the particles in the geopolymer composition can be dispersed, thereby delaying the curing reaction of the composition. Furthermore, the delayed curing reaction effect of the dispersant disappears within a few hours. Therefore, if a geopolymer composition includes this dispersant, it is possible to achieve both maintaining high fluidity for a long time and exhibiting high strength in a short period of time.

[0085] In this specification, the term "polycondensate-based dispersant comprising polyalkylene glycol monophenyl ether as a partial structure (specifically, a polycondensate-based dispersant comprising polyalkylene glycol monophenyl ether as a partial structure in an aqueous solution)" is not particularly limited as long as it is an aqueous solution of a polymer having the aforementioned function and a specified structure. Examples of such dispersants include aqueous solutions of polymers comprising a polycondensate having the following structural units A, B, C, and D.

[0086] Structural unit A: at least one polyethylene glycol monophenyl ether represented by the following formula (1).

[0087]

[0088] [wherein m in formula (1) is an integer from 3 to 280]

[0089] Structural unit B: a cyclic compound having at least one hydroxyl group and its derivative. 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.

[0090] Structural unit C: phenol, polyethylene glycol monophenyl ether having 1 or 2 repeating numbers of ethylene oxide, or a phenoxyethyl derivative containing a phosphate or phosphonate. For example, 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-phosphonooxyethoxy)phenoxy]ethyl phosphate, 2-[4-(2-phosphonooxyethoxy)phenoxy]ethyl phosphonate, methoxyphenol, and mixtures thereof.

[0091] Structural unit D: Aldehydes, for example, at least one aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, glyoxylic acid, benzaldehyde, benzaldehydesulfonic acid, benzaldehydedisulfonic acid, vanillin, isovanillin, and mixtures thereof.

[0092] The amount (mass %) of the dispersant (aqueous solution) blended relative to the total mass of the geopolymer composition can be adjusted appropriately depending on its type, concentration, etc., but is preferably 0.5% to 3.5% by mass. When the amount (mass %) of the dispersant (aqueous solution) blended is 0.5% by mass or greater, the aforementioned dispersant function can be effectively exerted, and both long-term high fluidity and short-term high strength can be more reliably achieved. When the amount (mass %) of the dispersant (aqueous solution) blended is 3.5% by mass or less, separation and bleeding of the geopolymer composition caused by excessive addition of the dispersant can be suppressed.

[0093] The amount (mass %) of the dispersant (aqueous solution) blended relative to the total mass of the geopolymer composition is more preferably 0.8 mass % or more, and even more preferably 0.85 mass % or more. Furthermore, the amount (mass %) of the dispersant (aqueous solution) blended is more preferably 2.5 mass % or less, and even more preferably 2.0 mass % or less.

[0094] The concentration (concentration of aqueous solution) and the amount (mass %) of the dispersant may be appropriately adjusted so that the total moisture content of the geopolymer composition of this embodiment is within the range of 10% to 13% by mass. In other words, the amount (mass %) of water contained in the dispersant may be appropriately adjusted based on the amount (mass %) of added water and the amount (mass %) of water contained in the activator so that the total moisture content is within the range of 10% to 13% by mass.

[0095] <Other materials>

[0096] The geopolymer composition of this embodiment may also contain any material commonly added as a raw material for mortar, concrete, etc., as long as the effect of improving fluidity and strength is not impaired. For example, it may contain an inert filler, a powder that is inactive against alkali, or various additives. Examples of inert fillers include cement and calcium carbonate. Examples of various additives are not particularly limited and include conventionally known components such as fluidizers, shrinkage reducers, rust inhibitors, waterproofing agents, defoamers, dust suppressants, and pigments.

[0097] <Total moisture content of geopolymer composition>

[0098] The total moisture content of the geopolymer composition of this embodiment is 10% to 13% by mass. By setting the total moisture content to 10% or more, the effect of reducing the amount of silica fume added on the fluidity of the composition can be compensated. As a result, the geopolymer composition can maintain good fluidity for a long period of time. By setting the total moisture content to 13% or less, the occurrence of bleeding can be reduced, and the desired high-strength cured product can be obtained in a short period of time.

[0099] The total moisture content is preferably 10.5% by mass or more, more preferably 11% by mass or more, further preferably 11.5% by mass or more, and particularly preferably 11.8% by mass or more. Furthermore, the total moisture content is preferably 12.8% by mass or less, more preferably 12.5% by mass or less, and further preferably 12.3% by mass or less.

[0100] As described above, the total moisture content of the geopolymer composition can be set within the range of 10% to 13% by mass by adjusting the amount (mass %) of added water, the amount (mass %) of water contained in the activator, and the amount (mass %) of water contained in the dispersant to appropriate values. In particular, by appropriately varying the amount (mass %) of added water, the total moisture content can be easily adjusted within this range.

[0101] <Method for preparing geopolymer composition>

[0102] The geopolymer composition of this embodiment can be prepared using 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, an active filler (e.g., an active filler comprising fly ash (preferably untreated fly ash) and blast furnace slag fine powder) as the main powder raw material and aggregate are mixed in predetermined amounts. In the subsequent kneading step, water, an activator, and a dispersant are further added to the powder mixture in predetermined amounts, and the mixture is mixed and kneaded. The mixing and kneading methods are not particularly limited; any method known to those skilled in the art using a mixer, etc., can be employed.

[0103] In the aforementioned method for preparing a geopolymer composition, a powder mixture can be prepared in advance by mixing an active filler (e.g., an active filler comprising fly ash (preferably untreated fly ash) and blast furnace slag fine powder) as the main powder raw material and aggregate in predetermined proportions. This powder mixture can then be used as a premixed geopolymer composition. Specifically, prior to construction or operation, water, an activator, and a dispersant in predetermined proportions are added to the premixed geopolymer composition, followed by mixing and kneading. This allows for the easy preparation of any desired amount of geopolymer composition on-site.

[0104] According to the geopolymer composition of the present embodiment, it is possible to take into account both long-term good fluidity and utilize a simple method to show the high strength of a solidified body in a short period of time. If ensuring long-term good fluidity, the geopolymer composition can be well processed at the manufacturing site of the solidified body product. If it is possible to utilize a simple method to show the high strength of a solidified body in a short period of time, even if long-term curing or expensive steam curing are not carried out, a solidified body of equal strength can be obtained by conventional curing such as in air or under a sealed environment. Moreover, according to the geopolymer composition of the present embodiment, the amount of silica fume that causes high cost can be suppressed, and the blast furnace slag fine powder as an industrial by-product can be efficiently and effectively utilized. Therefore, it is advantageous from the viewpoint of reducing manufacturing costs and reducing environmental load.

[0105] 2. Geopolymer solidified body and its manufacturing method

[0106] The geopolymer solidified body of the present embodiment is a solidified material of the geopolymer composition of the aforementioned embodiment. The geopolymer solidified body has any shape that can be formed using any molding method, construction method, etc. In short, this geopolymer solidified body can be manufactured using a method comprising the following steps: as described above, the geopolymer composition of the aforementioned embodiment is mixed and kneaded, and then solidified. Specifically, the geopolymer solidified body can be manufactured using the following method. First, the geopolymer composition after mixing, kneading, and preparation is molded or constructed using any method known to those skilled in the art, such as smearing, spraying, or pasting using a trowel in a molding or plastering project using a template. Then, for the geopolymer composition after molding or construction, even without complex treatments such as steam curing, by carrying out conventional curing such as in air or under a sealed environment, a high-strength geopolymer solidified body can be manufactured in a short period of time.

[0107] Furthermore, when a geopolymer cured body is produced using a template from the geopolymer composition of the aforementioned embodiment, it is preferable to apply a stripping agent or the like to the template in advance. The stripping agent is not particularly limited as long as it is any stripping agent known to those skilled in the art that imparts stripping properties to the cured geopolymer composition (i.e., the geopolymer cured body).

[0108] The geopolymer solidified body of this embodiment is not particularly limited and includes, for example, blocks for roads or bank protection; blocks for storm drains or irrigation channels; precast products such as tiles, bricks, sewer pipes, pile foundations, columns, and sleepers; and cast-in-place products such as cast-in-place concrete, shotcrete, concrete repairs, and dam concrete.

[0109] While this specification discloses various embodiments of the technology as described above, the main technologies are summarized below.

[0110] The first aspect of the present invention relates to a geopolymer composition comprising: an active filler; an aggregate; an activator; a dispersant; and added water, wherein:

[0111] The geopolymer composition does not contain silica fume, or contains less than 1% by mass of silica fume relative to the total mass of the geopolymer composition.

[0112] The total moisture content of the geopolymer composition is 10% to 13% by mass.

[0113] The active filler comprises: 35% by mass or more of blast furnace slag fine powder relative to the total mass of the active filler; and coal ash, and

[0114] The dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure.

[0115] In the geopolymer composition, preferably, the geopolymer composition does not contain silica fume.

[0116] The second aspect of the present invention relates to a geopolymer solidified body, which is a solidified product of the geopolymer composition according to the first aspect.

[0117] The third aspect of the present invention relates to a method for producing a geopolymer solidified body, comprising the steps of mixing and kneading the geopolymer composition according to the first aspect, and then solidifying the geopolymer composition.

[0118] Example

[0119] Hereinafter, the present invention will be further described in detail with reference to Examples, but the present invention is not limited in any way by these Examples.

[0120] In this example, various geopolymer compositions with different raw material ratios were actually prepared, and the geopolymer compositions were evaluated (fluidity test of the geopolymer composition, water bleeding test of the geopolymer composition, and uniaxial compressive strength test of the cured geopolymer composition).

[0121] 1. Preparation of Geopolymer Compositions

[0122] Hereinafter, the raw materials and the preparation methods of the geopolymer compositions of the Examples and Comparative Examples will be described in detail.

[0123] [Raw materials for geopolymer compositions]

[0124] The raw materials of the geopolymer compositions used in the Examples and Comparative Examples are shown below.

[0125] Fly ash (untreated fly ash): Fly ash collected as an industrial byproduct from thermal power plants was used directly. Specifically, a mixture of fly ash captured by an electrostatic precipitator and bottom ash crushed by a pulverizer from ash clumps that adhered and grew within the boiler was used. In other words, untreated fly ash was used directly, without undergoing rigorous pretreatment to achieve uniform quality (in other words, treatment that complies with the standards for fly ash for concrete specified in JIS A 6201:2015).

[0126] Blast furnace slag powder: "Keiment" manufactured by Kobelco Slag Products Co., Ltd. (specific surface area 4700cm 2 / g (approximately)

[0127] Silica fume: MasterCrete SF 5000, manufactured by Pozzolith Solutions, bulk density: 2.2 g / cm 3

[0128] Aggregate (blast furnace slag fine aggregate): "Shinkosand" manufactured by Kobelco Slag Products Co., Ltd. (maximum particle size 2.5 mm, sieve mass fraction 55% when the nominal mesh size is 0.6 mm)

[0129] Add water: tap water

[0130] Activator (aqueous solution): MasterCrete AC 5025, manufactured by Pozzolith Solutions

[0131] Dispersant (aqueous solution): an aqueous solution of the compound described in Example 5 of Japanese Patent Publication No. 6290176 (the aqueous solution of the compound can be produced by the following method. First, 300 parts by mass of poly(ethylene oxide) monophenyl ether (average molecular weight 2000 g / mol), 46.2 parts by mass of 3,4-dihydroxybenzoic acid, 33 parts by mass of 2-phenoxyethyl phosphate and 1 part by mass of paraformaldehyde were charged into a reactor equipped with a stirrer and a metering pump and capable of heating at 90°C under nitrogen. 9.9 parts by mass. The reaction mixture was then heated to 110°C while stirring, and then 41 parts by mass of methanesulfonic acid (70%) was added over 25 minutes so that the reaction temperature did not exceed 115°C. After metered addition, the reaction mixture was further stirred at 110°C for 2.5 hours. The reaction mixture was then cooled, mixed with 350 parts by mass of water, and heated at 100°C for 30 minutes. Finally, the mixture was neutralized with a 50% caustic soda solution to a pH of approximately 7.0.

[0132] [Method for preparing geopolymer composition]

[0133] The raw materials listed in Table 1 below were blended in various mass % (relative to the total mass of the composition) to prepare geopolymer compositions for Examples 1 and 2 and Comparative Examples 1 to 4. Specifically, fly ash (untreated fly ash) as an active filler and blast furnace slag fine powder were first mixed in the respective blending amounts shown in Table 1 below. In Comparative Example 1, silica fume was also added as an active filler and mixed. Next, blast furnace slag fine aggregate was added to this mixed powder as an aggregate and mixed. Finally, tap water as additional water, an activator (aqueous solution), and a dispersant (aqueous solution) were added to the mixture in the respective blending amounts and mixed using a Hobart mixer.

[0134] The total moisture content in the geopolymer composition was calculated by adding the amount of tap water (mass %) used as added water, the amount of water contained in the activator (mass %), and the amount of water contained in the dispersant (mass %). The amount of water contained in the activator (mass %) and the amount of water contained in the dispersant (mass %) were determined by subtracting the solid content (mass %) of each activator or dispersant from the amount of their respective aqueous solutions (mass %). The solid content (mass %) was determined by evaporating the sample to dryness at 110°C for approximately 15 minutes using an A&D moisture analyzer ("MX-50").

[0135]

[0136] 2. Evaluation of Geopolymer Composition

[0137] Using each geopolymer composition prepared as described above, a fluidity test, a water bleeding test, and a uniaxial compressive strength test of the geopolymer composition were conducted. The test methods and test results are described in detail below.

[0138] [Flowability test of geopolymer composition]

[0139] The fluidity of the geopolymer composition was measured according to the flow test specified in JIS R 5201:2015 (Physical testing methods for cement). However, the flow test was performed without tamping.

[0140] [Bleeding test of geopolymer composition]

[0141] A water bleeding test on a geopolymer composition was conducted using the following method. A total of 1.5 L of raw geopolymer composition materials were kneaded and the kneaded composition was allowed to stand for 1 hour. After 1 hour, the water that rose to the surface of the composition was removed using a pipette. The volume of water removed was then measured using a graduated cylinder, and the degree of water bleeding was evaluated.

[0142] The results of the fluidity (mm) measurement of the geopolymer composition at each elapsed time (minutes) and the results of the water bleeding test are summarized and shown in Table 2 below. Figure 1 The results of the fluidity tests of the geopolymer compositions shown in Table 2 below are shown in the graph of FIG. Figure 1 Here, the target fluidity represents the fluidity benchmark typically desired for geopolymer compositions, i.e., 200 mm.

[0143]

[0144] [Uniaxial compressive strength test of cured geopolymer composition]

[0145] The uniaxial compressive strength of cured geopolymer compositions was measured using the following method. Each prepared geopolymer composition was placed in a cylindrical mold with a diameter of 5 cm and a height of 10 cm. The molded product was sealed and cured for the respective ages shown in Table 2. The molded product was then demolded. After demolding, the uniaxial compressive strength of the molded product was measured in accordance with JIS A 1108:2018.

[0146] The results of the uniaxial compressive strength test at each material age (strength measurement day) are shown in Table 3 below. Figure 2 The graph shows the uniaxial compressive strength test results of the cured products of the geopolymer compositions shown in Table 3 below. Figure 2 The target strength in the figure represents a high strength standard generally expected for a cured product of a geopolymer composition, namely, 18 MPa.

[0147] Table 3

[0148]

[0149] [Investigation]

[0150] As shown in Table 1 above, the geopolymer composition of Comparative Example 1 contains a large amount of silica fume. Figure 1 and Figure 2As shown in FIG. 1 , the geopolymer composition of Comparative Example 1 exceeded the target fluidity of 200 mm except for the 5-minute point, and no bleeding occurred. Furthermore, the strength of the cured product exceeded the target strength on the 28th day. However, since the geopolymer composition of Comparative Example 1 contains a large amount of expensive silica fume, the production cost of using this geopolymer composition to manufacture various cured products is high. Furthermore, with respect to the fluidity of the geopolymer composition, a better fluidity would be more suitable.

[0151] Compared to the geopolymer composition of Comparative Example 1, the geopolymer composition of Comparative Example 2 has no significant differences in the proportions of the other components, except for the absence of silica fume. Specifically, the proportion of blast furnace slag fine powder in the active filler and the total moisture content of the geopolymer composition of Comparative Example 2 are roughly similar to those of the geopolymer composition of Comparative Example 1. However, the geopolymer composition of Comparative Example 2 fails to achieve the target flowability of 200 mm, and the strength of the cured product also fails to reach the target strength.

[0152] On the other hand, like the geopolymer composition of Comparative Example 2, the geopolymer compositions of Examples 1 and 2 do not contain silica fume. However, as shown in Tables 2 and 3 above, Figure 1 and Figure 2 As shown, the geopolymer compositions of Examples 1 and 2 significantly exceeded the target fluidity of 200 mm for an extended period, exhibited no bleeding, and achieved cured product strength exceeding the target strength on day 28. In particular, the fluidity of the geopolymer compositions of Examples 1 and 2 even exceeded 300 mm for an extended period, significantly exceeding expectations even when compared to the conventional geopolymer composition of Comparative Example 1, which contained a large amount of silica fume. This is presumably due to the fact that the geopolymer compositions of Examples 1 and 2 contained a specific type of dispersant, a high proportion of blast furnace slag fine powder in the active filler, and an appropriately adjusted total moisture content.

[0153] That is, Comparative Example 2 does not contain as much silica fume as Comparative Example 1, and the mixing ratio of the blast furnace slag fine powder in the active filler is small and the total moisture content is also small, so it is estimated that the effects of fluidity and strength cannot be obtained.

[0154] The geopolymer compositions of Comparative Examples 3 and 4 also did not contain silica fume. In the geopolymer composition of Comparative Example 3, similar to Example 1, the blast furnace slag fine powder ratio in the active filler was high, but the total moisture content was excessive. Therefore, although the target fluidity of 200 mm was exceeded, bleeding occurred, and the strength of the cured product did not reach the target strength. In the geopolymer composition of Comparative Example 4, similar to Example 1, the blast furnace slag fine powder ratio in the active filler was high, but the total moisture content was high. Therefore, although the target fluidity of 200 mm was exceeded and bleeding did not occur, the strength of the cured product did not reach the target strength.

[0155] This application is based on Japanese patent application No. 2023-000433 filed on January 5, 2023, and the contents are incorporated into this application.

[0156] The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is indicated not by the above description but by the claims, and is intended to encompass all modifications within the meaning and scope of the claims.

[0157] Industrial applicability

[0158] According to embodiments of the present invention, a geopolymer composition can be obtained that reduces the amount of silica fume incorporated, while maintaining excellent long-term fluidity and achieving high strength in a cured product in a short period of time using a simple method. Consequently, the production cost of the geopolymer composition can be reduced. In particular, even when fly ash, which has not been treated to meet the standards for fly ash for concrete specified in JIS A6201:2015 and is an industrial byproduct, is included as an active filler, the same effects can be achieved, making it suitable from an environmental perspective.

Claims

1. A geopolymer composition, characterized in that Contains: active filler; aggregate; activator; dispersant; and added water, wherein, The geopolymer composition does not contain silica fume, or contains less than 1% by mass of silica fume relative to the total mass of the geopolymer composition. The total moisture content of the geopolymer composition is 10% to 13% by mass. The active filler comprises: 35% by mass or more of blast furnace slag fine powder relative to the total mass of the active filler; and coal ash, and The dispersant is a polycondensate-based dispersant containing polyalkylene glycol monophenyl ether as a partial structure.

2. The geopolymer composition according to claim 1, characterized in that The geopolymer composition does not contain silica fume.

3. A geopolymer solidified body, characterized in that A cured product of the geopolymer composition according to claim 1 or 2.

4. A method for producing a geopolymer solidified body, characterized in that include: The geopolymer composition according to claim 1 or 2 is mixed and kneaded, and then cured.

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