Method for producing geopolymer cured product, geopolymer cured product, method for producing geopolymer composition, and geopolymer composition

Abstract

Provided is a method for producing a geopolymer cured product that can prevent a decrease in fluidity of a geopolymer composition even when a large amount of fine blast furnace slag aggregate is used as an aggregate, and that can obtain a geopolymer cured product with a small drying shrinkage. The method for producing a geopolymer cured product is characterized by comprising: a first step of producing a geopolymer composition by mixing an aggregate containing fine blast furnace slag aggregate, a powder containing microfine blast furnace slag, an alkali metal solution, gluconic acid, and water; and a second step of curing the geopolymer composition produced in the first step.

Description

Technical Field

[0001] This invention relates to a method for manufacturing geopolymer solidified products, geopolymer solidified products, a method for manufacturing geopolymer compositions, and geopolymer compositions. Background Technology

[0002] In recent years, as a solution to global warming, research has been conducted on materials used in concrete that minimize carbon dioxide (CO2) emissions during their manufacturing process. Previously, Portland cement was primarily used in concrete, but its manufacturing process generates significant amounts of CO2, posing a challenge. Therefore, geopolymers have gained attention as a technology for manufacturing concrete without using Portland cement.

[0003] Geopolymers are known to have a structure in which powders are bonded together using condensation polymers of silica as a binder. The complexes used in these geopolymers are primarily amorphous aluminum silicate powders and alkali metal solutions. The powders used can include kaolin, clay, fly ash, silica fume, blast furnace slag powder, etc., and the alkali metal solutions can include sodium hydroxide, potassium hydroxide, water glass, or potassium silicate, etc. Furthermore, by appropriately mixing admixtures into the aforementioned alkali metal solutions and then curing them, a cured product similar to that used in Portland cement can be obtained. Additionally, by adding coarse aggregate as aggregate, a cured product similar to that of concrete can be obtained.

[0004] In previous geopolymer studies, powders composed of a mixture of fly ash and blast furnace slag fines were commonly used as the aforementioned powder. Here, the fly ash and blast furnace slag fines are obtained in large quantities as byproducts of combustion furnaces and blast furnaces, and their use is ideal from the perspective of efficient resource utilization. However, in geopolymer research, regarding aggregates, natural materials such as sand, gravel, and crushed stone have been utilized, while studies using byproducts such as fine blast furnace slag aggregates are almost nonexistent. Therefore, there are few studies exploring the effects of geopolymer compositions using fine blast furnace slag aggregates on the setting time, strength, and freeze-thaw resistance of the geopolymer cured products made from such compositions.

[0005] Against this backdrop, methods for manufacturing geopolymer compositions and geopolymer admixtures, as shown below, have been proposed. For example, Patent Document 1 discloses a method for manufacturing a geopolymer composition by mixing a filler consisting of fly ash and blast furnace slag, an alkaline solution, and aggregate, and then curing it to solidify it. In the method described in Patent Document 1, a geopolymer composition is prepared by combining fly ash with at least 10% blast furnace slag micro-powder.

[0006] Furthermore, Patent Document 2 discloses an admixture for geopolymers that combines a shrinkage-reducing agent formed from an oxyalkylene alkyl ether compound and a shrinkage-reducing aid formed from an aliphatic hydroxycarboxylic acid compound. The admixture disclosed in Patent Document 2 is a geopolymer additive that uses fly ash and blast furnace slag micro-powders as powders and is used to adjust setting time, improve fluidity, and reduce drying shrinkage.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 6408454

[0010] Patent Document 2: Japanese Patent Application Publication No. 2017-202964 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, the aforementioned prior art has the following problems. In Patent Document 1, the amount of blast furnace slag powder relative to fly ash is small, resulting in a total of only 30% by volume of blast furnace slag powder relative to fly ash. Furthermore, the method for manufacturing the geopolymer composition described in Patent Document 1 was developed using only natural sand as fine aggregate. Thus, in the method for manufacturing the geopolymer composition described in Patent Document 1, if more than 30% by volume of blast furnace slag powder is added to the fly ash mixture, and further fine aggregates of blast furnace slag are used, there is a risk of increased reaction between the blast furnace slag powder and the alkaline solution, a significant decrease in the fluidity of the geopolymer composition, and difficulties in workability.

[0013] Patent Document 2 discloses several shrinkage-reducing agents and reveals that they can reduce the drying shrinkage of geopolymer mortar. Here, as an example, river sand is shown as the fine aggregate and limestone crushed stone is shown as the coarse aggregate.

[0014] In Patent Documents 1 and 2, natural sand was used as fine aggregate, but the use of natural materials poses a risk of environmental impact. From this perspective, substances to replace sand as fine aggregate were explored. One such alternative is blast furnace slag fine aggregate. However, since blast furnace slag fine aggregate has the same composition as blast furnace slag powder, it may react with alkali metal solutions, promoting solidification. Furthermore, using blast furnace slag fine aggregate reduces the fluidity of the geopolymer composition, and air trapping becomes easier, leading to bleeding.

[0015] The present invention was developed in view of the above-mentioned situation faced by the prior art, and its object is to provide a method for manufacturing geopolymer solids, a geopolymer solid, a geopolymer solid, and a geopolymer composition and the same method, which can prevent the reduction of the fluidity of the geopolymer composition even when a large amount of blast furnace slag fine aggregate is used as aggregate, and can also obtain geopolymer solids with low drying shrinkage.

[0016] Methods for solving problems

[0017] The inventors of this application conducted repeated and careful research to solve the aforementioned problems faced by the prior art. As a result, they discovered that by mixing aggregate containing fine blast furnace slag aggregate, powder containing blast furnace slag micro powder, alkali metal solution, gluconic acid, and water as raw materials, it is possible to manufacture a large quantity of geopolymer compositions with excellent fresh-mixed properties containing fine blast furnace slag aggregate. By further curing the above-mentioned geopolymer composition, it is possible to manufacture geopolymer cured products with the same properties as concrete and excellent drying shrinkage, thereby developing the present invention.

[0018] The present invention is based on the above insights, and its main points are as follows. That is, the present invention proposes (1) and (2) as shown below.

[0019] (1) A method for manufacturing geopolymer solidified material, characterized in that it includes: a first step of mixing aggregate containing fine blast furnace slag aggregate, powder containing micro powder of blast furnace slag, alkali metal solution, gluconic acid and water to manufacture a geopolymer composition, and a second step of curing the geopolymer composition manufactured in the aforementioned first step.

[0020] It should be noted that, regarding the method for manufacturing geopolymer cured products involved in this invention, the following are considered to be more preferred solutions:

[0021] (a) The aforementioned powder is a powder containing the fly ash in a volume ratio of 10:90 to 100:0, based on the aforementioned blast furnace slag micro powder to fly ash.

[0022] (b) As the fine aggregate in the aforementioned aggregate, the aforementioned fine aggregate contains more than 50% by volume of the aforementioned blast furnace slag fine aggregate.

[0023] (c) In addition, the geopolymer solidified product involved in the present invention is a geopolymer solidified product manufactured by the above-described geopolymer solidified product manufacturing method.

[0024] (2) The method for manufacturing geopolymer composition involved in this invention is a method for manufacturing geopolymer composition by mixing aggregate containing fine blast furnace slag aggregate, powder containing micro powder of blast furnace slag, alkali metal solution, gluconic acid and water.

[0025] (d) In addition, the geopolymer composition involved in the present invention is a geopolymer composition manufactured by the above-described method for manufacturing geopolymer compositions.

[0026] Invention Effects

[0027] According to the present invention, blast furnace slag fine aggregate can be used as aggregate in a proportion of 50% by volume or more in the geopolymer composition, and a formulation that reduces drying shrinkage, considered a weakness of geopolymers, can be achieved. Furthermore, the method for manufacturing geopolymer solidified products of the present invention can suppress the use of natural fine aggregates such as mountain sand, river sand, sea sand, and crushed sand manufactured in quarry plants, which are commonly used in geopolymers. Therefore, the geopolymer solidified product obtained by the method for manufacturing geopolymer solidified products of the present invention is a more environmentally friendly geopolymer solidified product. Attached Figure Description

[0028] [ Figure 1 [This is a flowchart illustrating a method for manufacturing geopolymer solidified products according to embodiments of the present invention.]

[0029] [ Figure 2 [This is a flowchart illustrating a method for manufacturing geopolymer solidified products according to embodiments of the present invention.] Detailed Implementation

[0030] [First Implementation]

[0031] Figure 1 and Figure 2 A flowchart illustrating the method for manufacturing geopolymer solidified products according to this embodiment is provided. Figure 1 A basic flow chart illustrating the manufacturing method of a geopolymer solidified product without coarse aggregate, where the geopolymer composition serves as a precursor for the solidified product. Figure 2 A basic flow chart illustrating the manufacturing method of a geopolymer solidified product when the geopolymer composition, which serves as a precursor to the solidified product, contains coarse aggregate. (See attached diagram.) Figure 1 and Figure 2 As shown, the method 100 for manufacturing geopolymer solidified material according to this embodiment includes: a first step 101 of mixing aggregate containing fine blast furnace slag aggregate, powder containing blast furnace slag micro powder, alkali metal solution, gluconic acid and water to manufacture a geopolymer composition; and a second step 102 of curing the geopolymer composition manufactured in the aforementioned first step. Each step will be described below.

[0032] <First step in manufacturing geopolymer compositions>

[0033] The method for manufacturing geopolymer solidified products in this embodiment includes a first step of mixing aggregate containing fine blast furnace slag aggregate, powder containing blast furnace slag micro powder, or powder further containing fly ash, alkali metal solution, gluconic acid, and water to produce a geopolymer composition. The geopolymer solidified product manufactured by the method of this embodiment is obtained by curing the geopolymer composition. That is, the geopolymer composition manufactured in the first step is a precursor to the geopolymer solidified product. Here, geopolymer refers to a general term for amorphous polymers obtained by reacting alumina-silica powder such as blast furnace slag micro powder and fly ash with an alkali-silica solution such as sodium silicate aqueous solution or sodium hydroxide aqueous solution.

[0034] The raw materials for the geopolymer composition manufactured in the first process are powders mainly containing blast furnace slag micro powder (GGBF) or powders further containing fly ash (FA), alkaline solution, gluconic acid, and aggregates containing blast furnace slag fine aggregate (BFS). The following describes each component contained in the geopolymer composition manufactured in the first process.

[0035] (Powder)

[0036] The powder may contain silicic acid, silicon dioxide, aluminum oxide, and calcium oxide dissolved in alkaline solutions. The main component of the powder is a vitreous (amorphous) material that undergoes a geopolymer formation reaction in the presence of alkali. The silicon (Si) and aluminum (Al) contained in the powder as the main components are dissolved from the powder by the alkali contained in the alkaline solution, and form a geopolymer as a silicon (Si)-silicon (Si) condensate through condensation reactions accompanied by dehydration.

[0037] The powder contains blast furnace slag fine powder (GGBF) as the main component. That is, the powder can be obtained by processing blast furnace water-quenched slag, a byproduct of molten iron production in a blast furnace. Alternatively, fly ash (FA) and silica fume (SF), byproducts of thermal power plants, can be further added to the powder. Specifically, the standard product specified in JIS A 6206:2013 can be used as the blast furnace slag fine powder. Furthermore, the standard product specified in JIS A 6201:2015 can be used as the fly ash (FA), for example.

[0038] Regarding the amount of powder contained in the in-situ polymer composition, in the absence of coarse aggregate, it is preferably adjusted to 500-900 kg / m³, based on the total amount of blast furnace slag powder (GGBF) and fly ash (FA). 3 If the powder's mixing amount (unit quantity) is 500 kg / m³ 3The above describes a geopolymer composition necessary for producing geopolymer cured products with low drying shrinkage, and is therefore preferred. If the powder dosage is 900 kg / m³... 3 Therefore, no unreacted powder will be produced, which is preferable. Furthermore, regarding the amount of the powder, when using coarse aggregate, it is preferable to adjust the total amount of blast furnace slag fine powder (GGBF) and fly ash (FA) to 200–600 kg / m³. 3 It should be noted that the mixing ratio of blast furnace slag micro powder (GGBF) and fly ash (FA) in the powder can be appropriately set to ensure the setting start time and setting end time of the geopolymer composition. In this invention, a suitable geopolymer solidified product is obtained by optimizing the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) and the volume ratio of blast furnace slag fine aggregate in the fine aggregate. The volume ratio of each material can be calculated by dividing the unit volume mass of the mixing table by the density of each material. The density referred to here is the density specified in JIS R 5201:2015 for blast furnace slag micro powder (GGBF) and fly ash (FA), and the density specified in JIS A1109:2020 for fine aggregate.

[0039] Furthermore, the powder used in the first process is mainly composed of powder containing blast furnace slag micron powder (GGBF) or powder further containing fly ash (FA). However, without departing from the purpose of this invention, it may contain other industrial byproducts such as metakaolin (a calcined clay mineral), rice husk ash, palm ash from burning oil palm residue, waste glass, municipal solid waste incineration ash, and sewage sludge incineration ash. Thus, the geopolymer composition produced in the first process is mainly composed of powder containing blast furnace slag micron powder or powder further containing fly ash (FA), and therefore has the characteristics of higher silicon (Si) and aluminum (Al) content and lower calcium (Ca) content compared to cement concrete.

[0040] (Alkaline solution)

[0041] For alkaline solutions, aqueous solutions containing compounds such as sodium hydroxide, potassium hydroxide, water glass, or potassium silicate are ideal. Since geopolymers are cured by an alkaline source, alkali metal compounds containing potassium or sodium are required. Regarding the amount of alkali metal compound, it is preferable to adjust the molar ratio (mass ratio) of silicon (Si) contained in the blast furnace slag powder, fly ash, and silica fume in the powder to the molar ratio (mass ratio) of alkali metals (e.g., Na, K) in the alkaline solution to be between 1.0 and 6.0. This is because if the molar ratio (mass ratio) of silicon (Si) to alkali metal is 1.0 or higher, the polymerization reaction of silicon (Si) proceeds sufficiently; if the molar ratio (mass ratio) of silicon (Si) to alkali metal is 6.0 or lower, the cured geopolymer obtained by curing the geopolymer composition can ensure sufficient strength even at an early age.

[0042] The concentration of the alkaline solution used in the first step of manufacturing the geopolymer composition can be appropriately set taking into account the water content and the amount of alkali (OH) in the geopolymer composition. For example, an aqueous solution of sodium hydroxide (density 1.5 g / cm³) can be used. 3 In the case of an alkaline solution, the concentration of the sodium hydroxide aqueous solution can be set to 48% by mass. The unit water volume can be determined by taking into account the water contained in the alkaline solution, the gluconic acid solution, and the water generated during the polycondensation reaction with silicon (Si).

[0043] The unit water consumption varies depending on the required strength, ranging from 100 to 300 kg / m³ without the use of coarse aggregate. 3 Adjusting the range is ideal. Additionally, when using coarse aggregate, the unit water content is 60–200 kg / m³. 3 It is ideal to adjust the range of water content. The unit water volume can be determined taking into account the water content in the alkaline solution and gluconic acid solution. If the unit water volume is above the lower limit of each range, the flowability of the polymer composition can be ensured, which is preferred. In addition, if the unit water volume is below the upper limit of each range, drying shrinkage can be suppressed.

[0044] (aggregate)

[0045] The aggregate contained in the geopolymer composition includes fine blast furnace slag aggregate. The aggregate may also include other fine aggregates besides fine blast furnace slag aggregate. The aggregate may further include coarse aggregate. Regarding the aggregate used as a raw material for the geopolymer composition manufactured in the first step, aggregate containing fine blast furnace slag aggregate is used. Its particle size is preferably adjusted in a manner conforming to JIS A 5011-1:2018. This is because by including fine blast furnace slag aggregate in the aggregate, it is expected to reduce the drying shrinkage of the cured geopolymer. Furthermore, it is preferable that the fine aggregate contains at least 50% by volume of fine blast furnace slag aggregate.

[0046] Regarding the amount of aggregate in the geopolymer composition, it is desirable to adjust the aggregate volumetric ratio (the volume of aggregate in the geopolymer composition) to be as high as possible. For example, when no coarse aggregate is included in the geopolymer composition, the aggregate volumetric ratio is expected to be 40% or more. Conversely, when coarse aggregate is included in the geopolymer composition, the aggregate volumetric ratio is expected to be 60% or more. Since the geopolymer cured product has a significant impact on drying shrinkage, increasing the aggregate volumetric ratio reduces the amount of geopolymer cured product, thereby reducing drying shrinkage. Increasing the coarse aggregate volumetric ratio is one common method for reducing the drying shrinkage of geopolymer cured product. Furthermore, coarse aggregate is generally readily available at low cost; increasing the coarse aggregate volumetric ratio (the volume of coarse aggregate in the geopolymer composition) also reduces the price of the compound obtained by mixing the geopolymer composition components, making it more economical and preferred.

[0047] The water absorption rate of the fine aggregate is preferably 3.5% or less. If the water absorption rate of the fine aggregate is 3.5% or less, the quality of the geopolymer composition manufactured in the first process can be maintained uniformly, and therefore this is preferred. For the same reason, the surface dry density of the fine aggregate is expected to be 2.5 g / cm³. 3 above.

[0048] As coarse aggregate, blast furnace slag coarse aggregate, natural coarse aggregate commonly used in concrete, or coarse aggregate whose particle size has been adjusted to meet JIS standards can be used. For example, natural aggregates specified in JIS 1110:2020 can be used as coarse aggregate. For the same reasons as using the aforementioned fine aggregate, the water absorption rate of this coarse aggregate is expected to be 3.0% or less. Furthermore, the surface-dry density of the coarse aggregate is expected to be 2.5 g / cm³. 3 above.

[0049] (gluconic acid)

[0050] Furthermore, in the first step of the method for manufacturing geopolymer cured products according to this embodiment, the geopolymer composition produced contains gluconic acid as an additive to ensure its fluidity and delay curing. That is, the method for manufacturing geopolymer cured products according to this embodiment is characterized by containing gluconic acid as a precursor of the geopolymer cured product, i.e., a raw material for the geopolymer composition. Glucosamine is an aliphatic hydroxycarboxylic acid and has a curing-delaying effect on the geopolymer composition.

[0051] The geopolymer composition produced in the first process contains powders containing blast furnace slag micronized powder (GGBF) or further containing fly ash (FA), and blast furnace slag fine aggregate as raw materials. Therefore, if only conventional admixtures are added, the reaction between silicon (Si) and aluminum (Al) contained in the powders and blast furnace slag fine aggregate and the alkali in the alkaline solution increases, resulting in a large amount of geopolymer formation and a significant reduction in the fluidity of the geopolymer composition. The reduced fluidity of the geopolymer composition significantly reduces its workability. Consequently, it becomes difficult to use the geopolymer composition with reduced fluidity to produce the desired geopolymer cured product.

[0052] Regarding this point, in the method for manufacturing geopolymer solidified products according to this embodiment, gluconic acid, an aliphatic hydroxycarboxylic acid, can be added as an additive to the geopolymer composition manufactured in the first step, thereby improving the flowability of the geopolymer composition. The gluconic acid contained in the geopolymer composition is believed to be supplied by calcium ions (Ca) from the blast furnace slag micropowder contained in the geopolymer composition manufactured in the first step. 2+ Chelation and ion blocking inhibit reactions with alkali in alkaline solutions. As a result, the flowability of the geopolymer composition can be ensured, and the curing of the geopolymer composition can be delayed.

[0053] Using a gluconic acid aqueous solution (density 1.8 g / cm³) 3 When gluconic acid (at a mass percentage concentration of 50%) is used as a component of the geopolymer composition, it is expected to achieve a concentration of 0.1–60 kg / m³. 3 The above-mentioned gluconic acid aqueous solution is used because the increased material cost and moisture content of the geopolymer composition lead to a delayed curing effect. It should be noted that the preferred amount of gluconic acid used is 1–40 kg / m³. 3 More preferably 2-40 kg / m 3 .

[0054] (Mix and match)

[0055] The mixing process is carried out by placing the various materials mentioned above into various mechanical mixers for stirring and mixing. There are no particular limitations on the mixer used for mixing, as long as it can fully mix the various materials to produce a polymer composition through the polycondensation reaction of silicon (Si) and aluminum (Al). For example, mortar mixers (compliant with JIS R5201) used for cement concrete, disc mixers, forced twin-shaft mixers, etc., can be used for mixing.

[0056] For example, as part of this mixing process, it is preferable to feed powder containing blast furnace slag micro powder (GGBF) as an active filler, or powder further containing fly ash (FA), and aggregate containing blast furnace slag fine aggregate into the aforementioned mixer, pre-mix these materials by dry mixing, and then add an alkaline solution. Alternatively, the mixing can be carried out at both low and high speed stages.

[0057] <Second step in curing the geopolymer composition>

[0058] The method for manufacturing a geopolymer cured product according to this embodiment includes a second step of curing the geopolymer composition manufactured in the first step. The reason for this is that by curing the geopolymer composition, the reaction between the silicon (Si) and aluminum (Al) contained in the geopolymer composition and the alkali contained in the alkaline solution proceeds sufficiently, resulting in the production of a geopolymer cured product. The second step of curing the geopolymer composition is preferably performed by room temperature curing or steam curing. Room temperature curing can be gas curing (e.g., temperature 20°C, humidity 60% RH) or water curing (e.g., temperature 20°C). On the other hand, steam curing is preferably performed using a device capable of maintaining a specified temperature and humidity. It should be noted that, for the purpose of increasing the initial strength of the geopolymer cured product, gas curing as pre-curing and steam curing by applying heat with steam at 60–80°C can also be combined.

[0059] The geopolymer composition produced in the first step is filled into a mold. To facilitate the removal of the geopolymer composition from the mold, a release agent such as wax can be applied inside the mold. The mold can be made of the same metal as conventional concrete molds, such as wood or steel. Examples of release agents include petroleum wax, animal and plant waxes, mineral wax, and synthetic wax.

[0060] Regarding the curing period of the geopolymer composition filled in the mold, it should be appropriately set in a manner that allows the reaction between the silicon (Si), aluminum (Al), and calcium (Ca) contained in the geopolymer composition and the alkali contained in the alkaline solution to fully proceed, thus forming a solidified geopolymer. For example, the curing period of the geopolymer composition can be set to 1 day, 3 days, 7 days, 28 days, 91 days, etc., depending on the properties of the geopolymer composition. However, in actual construction and product manufacturing, considering productivity and construction period, a wet curing period of 5 to 9 days, similar to that of conventional concrete, is desirable.

[0061] In the second step of the method for manufacturing geopolymer cured products according to this embodiment, the geopolymer composition is cured to become a geopolymer cured product.

[0062] The method for manufacturing geopolymer solidified products according to the first embodiment improves the flowability of the geopolymer composition (e.g., mortar flowability when the geopolymer composition does not contain coarse aggregate, slump or slump flowability when the geopolymer composition contains coarse aggregate), enhances its fresh mix properties, and enables the production of geopolymer solidified products with low drying shrinkage. Furthermore, the method for manufacturing geopolymer solidified products according to the first embodiment avoids the use of natural fine aggregates typically used in geopolymer solidified products, thus preventing environmental damage and resulting in more environmentally friendly geopolymer solidified products.

[0063] [Second Implementation]

[0064] Next, a method for manufacturing geopolymer solidified products according to the second embodiment of the present invention will be described. The method for manufacturing geopolymer solidified products according to this embodiment is characterized in that the powder used in the first step of the method for manufacturing geopolymer solidified products according to the first embodiment contains fly ash in a volume ratio of blast furnace slag micro powder to fly ash of 10:90 to 100:0.

[0065] In the method for manufacturing geopolymer solidified products according to this embodiment, if the mixing ratio of blast furnace slag micro powder to fly ash is 10:90 by volume, the polycondensation reaction of silicon (Si) and other components contained in the fly ash is promoted, which is preferred. Furthermore, if the mixing ratio of blast furnace slag micro powder to fly ash is 100:0 by volume, a large amount of blast furnace slag micro powder can be used, ensuring the strength of the geopolymer solidified product, which is also preferred. Thus, in the method for manufacturing geopolymer solidified products of this embodiment, since the geopolymer composition manufactured in the first step contains gluconic acid, even if a powder containing a large amount of blast furnace slag micro powder is used as a powder, its flowability can be ensured, and the rapid curing of the geopolymer composition can be delayed. Furthermore, the method for manufacturing geopolymer solidified products of this embodiment can obtain geopolymer solidified products with low drying shrinkage by curing the aforementioned geopolymer composition.

[0066] According to the above-described method for manufacturing geopolymer cured products in the second embodiment, by using a powder containing fly ash in a volume ratio of blast furnace slag micro powder to fly ash of 10:90 to 100:0, the setting start time and setting end time of the geopolymer composition can be adequately ensured, and a geopolymer composition with excellent workability can be obtained. Furthermore, a geopolymer cured product with low drying shrinkage that exhibits preferred quality as a secondary concrete product can be manufactured.

[0067] [Third Implementation Method]

[0068] Next, a method for manufacturing a geopolymer solidified product according to this embodiment will be described. The method for manufacturing a geopolymer solidified product according to this embodiment is characterized in that the fine aggregate contained in the geopolymer composition manufactured in the first step of the method for manufacturing a geopolymer solidified product according to the above embodiment contains 50% by volume or more of the aforementioned blast furnace slag fine aggregate.

[0069] Regarding the fine aggregate in the aggregate of the geopolymer composition produced in the first step of the method for manufacturing geopolymer solids in this embodiment, it is preferable that the aforementioned blast furnace slag fine aggregate contains at least 50% by volume of blast furnace slag fine aggregate, thus enabling the production of geopolymer solids with low drying shrinkage. As for the fine aggregate in the aforementioned geopolymer composition, it is sufficient that it contains at least 50% by volume of blast furnace slag fine aggregate; therefore, the aggregate can also be 100% by volume of blast furnace slag fine aggregate. Furthermore, as long as the fine aggregate in the aforementioned geopolymer composition contains at least 50% by volume of blast furnace slag fine aggregate, it is preferable that blast furnace slag, a byproduct of pig iron production in the blast furnace, can be utilized in large quantities and effectively, replacing natural sand such as mountain sand, sea sand, and crushed sand produced in a quarry.

[0070] According to the above-described method for manufacturing geopolymer solidified products in the third embodiment, by including blast furnace slag fine aggregates of 50% by volume or more in the fine aggregates used in the first step, it is possible to manufacture geopolymer solidified products that are more environmentally friendly and have less drying shrinkage.

[0071] [Fourth Implementation Method]

[0072] This embodiment describes a geopolymer solidified product manufactured using the method described in the above embodiment. Specifically, the geopolymer solidified product of this embodiment is a solidified product with low drying shrinkage obtained by curing a geopolymer composition with excellent fresh-mixed properties (mortar flowability, slump, or slump flowability, etc.) using powder containing blast furnace slag micron powder (GGBF) or powder further containing fly ash (FA) and aggregate containing fine blast furnace slag aggregate as raw materials. Therefore, it can be used as a substitute for secondary concrete products. Consequently, the geopolymer solidified product of this embodiment can be used for: protection of decayed ditch slopes, building blocks / bricks, aquatic structures such as fish (algae) reefs, stabilization treatment of heavy metal contaminated soil, renovation of decayed pond dams, renovation of embankments and seepage barriers within road embankments, solutions for weak foundations, applications in box foundation construction methods, and solidification treatment of soft clay.

[0073] Furthermore, the geopolymer cured product of this embodiment has excellent fire resistance and is not prone to alkali-silica reaction.

[0074] In addition, the geopolymer solidified in this embodiment has very little drying shrinkage, so it can be used as a building material for sleepers, external building blocks, U-shaped channels, driveway boundary blocks, airport apron paving, etc.

[0075] As explained above, according to the geopolymer solidified product of the fourth embodiment, in the aggregates that are raw materials for the geopolymer composition, fine aggregates including blast furnace slag fine aggregates are used, thereby enabling the production of geopolymer solidified products that can significantly reduce the drying shrinkage of the geopolymer composition.

[0076] [Fifth Implementation Method]

[0077] A method for manufacturing the geopolymer composition according to the fifth embodiment will be described. The method for manufacturing the geopolymer composition of this embodiment is characterized by being a method for manufacturing a geopolymer composition by mixing aggregate containing fine blast furnace slag aggregate, powder containing blast furnace slag micro powder (GGBF) or powder further containing fly ash (FA), alkali metal solution, gluconic acid and water.

[0078] The method for manufacturing the geopolymer composition according to this embodiment can produce a geopolymer composition as a precursor for a geopolymer cured product. That is, the method for manufacturing the geopolymer composition according to this embodiment corresponds to the first step of the method for manufacturing the geopolymer cured product described above. Because the geopolymer composition contains gluconic acid as an additive, even geopolymer compositions containing powders containing a large amount of blast furnace slag micro-powder and aggregates containing 50% by volume or more of blast furnace slag fine aggregates can produce geopolymer cured products with low drying shrinkage without reducing the fluidity of the geopolymer composition.

[0079] As explained above, in the method for manufacturing the geopolymer composition according to the fifth embodiment, the fine aggregate contained in the aggregate of the geopolymer composition is a fine aggregate containing 50% or more of blast furnace slag fine aggregate, thereby enabling the manufacture of a precursor of the geopolymer cured product, namely the geopolymer composition, which can significantly reduce the drying shrinkage of the geopolymer composition.

[0080] [Other Implementation Methods]

[0081] The present invention has been described above with reference to the embodiments described herein, but the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made regarding the structure and details of the present invention within the scope of the present invention.

[0082] Example

[0083] (Example 1)

[0084] The materials used as raw materials for the geopolymer composition in the method for manufacturing geopolymer cured products of the present invention are shown in Table 1. As shown in Table 1, powders, alkaline solutions, fine aggregates, coarse aggregates, and additives were used as materials for the geopolymer compositions used in the following examples. It should be noted that the symbols and physical properties of each material are shown in Table 1 along with their names. Regarding the physical properties of the powders, the density (g / cm³) is shown. 3 ) and specific surface area (cm²) 2 Regarding the physical properties of alkaline solutions, the density (g / cm³) is shown. 3 The surface dry density (g / cm³) is shown, along with the mass percentage concentration (%) and the physical properties of the fine aggregate. 3 The data includes the water absorption rate (%) and the density (g / cm³) of the admixture. 3 ) and mass percentage concentration (%).

[0085] [Table 1]

[0086]

[0087] The geopolymer composition of Example 1 comprises powder, alkaline solution, fine aggregate, additives, and water. For the powder, a mixture of blast furnace slag fine powder (GGBF) and silica fume (SF) was used. In this Example 1, the volume ratio of blast furnace slag fine powder (GGBF) to fly ash (FA) was set to 60:40. The fly ash (FA) used was Grade II ash possessing standard quality for fly ash. Additionally, gluconic acid was used as an additive.

[0088] The mixing of materials for the geopolymer composition was carried out in accordance with JIS R5201. Specifically, using a mortar mixer, specified amounts of water, sodium hydroxide, and gluconic acid were added, followed by silica fume (SF) and a powder containing blast furnace slag fine powder (GGBF) and fly ash (FA), and finally blast furnace slag fine aggregate (BFS) as fine aggregate. After mixing the materials for the geopolymer composition under specified conditions, the geopolymer composition was obtained. Furthermore, the mortar flow value of the obtained geopolymer composition was measured (15 castings) to evaluate the fluidity of the geopolymer composition. Table 2 shows the composition of the geopolymer composition, its proportions, and the results of the mortar flow value measurement. It should be noted that the mortar flow value measurement of the obtained geopolymer composition was carried out in accordance with JIS R5201.

[0089] (Compare Examples 1 and 2)

[0090] In Comparative Example 1, gluconic acid was not added as an admixture and the materials were mixed. In Comparative Example 2, sodium gluconate was used instead of gluconic acid, and the geopolymer composition was manufactured in the same manner as in Example 1. That is, in Examples 1, 1, and 2, in order to understand the effect of improving flowability due to the addition of admixtures, no admixture, gluconic acid, and sodium gluconate were used. Table 2 shows the results of the determination of the materials, proportions, and mortar flow values ​​of the geopolymer compositions.

[0091] [Table 2]

[0092]

[0093] As shown in Table 2, the mortar flow value (mm) of the geopolymer composition of Example 1 (composition (1): gluconic acid added) was 139 mm, the mortar flow value (mm) of the geopolymer composition of Comparative Example 1 (composition (2): no gluconic acid added) was 125 mm, and the mortar flow value (mm) of the geopolymer composition of Comparative Example 2 (composition (3): sodium gluconate added) was 119 mm. A comparison between Example 1 and Comparative Examples 1-2 shows that even with the addition of sodium gluconate as a material in the geopolymer composition, no improvement in the flowability of the geopolymer composition was observed.

[0094] On the other hand, as shown in Example 1, when gluconic acid is added as an admixture to the geopolymer composition, the mortar flowability (mm) of the geopolymer composition increases, and the fresh mix properties are improved. Therefore, in the subsequent formulation studies of the geopolymer compositions, a formulation using gluconic acid as an admixture will be used. It should be noted that if too much gluconic acid is added, the material cost of the geopolymer composition will increase, and adding gluconic acid in the form of an aqueous solution will increase the water content, which will also have a curing delay effect on the geopolymer composition. Therefore, when using the gluconic acid used in the examples shown in Table 1, it is desirable to use 2 to 40 (kg / m³) of gluconic acid. 3 )use.

[0095] (Examples 2-14)

[0096] In the method for manufacturing geopolymer solidified products of the present invention, in order to study the appropriate blending ratio of blast furnace slag micro powder (GGBF) and fly ash (FA) contained in the powder constituting the geopolymer composition, the volume ratio of blast furnace slag micro powder (GGBF) and fly ash (FA) is changed for mixing. Specifically, for formulations that do not use coarse aggregate, in Example 2, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 100:0; in Example 3, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 90:10; in Example 4, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 80:20; in Example 5, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 70:30; and in Example 6, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to... In Example 7, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 50:50. In Example 8, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 40:60. In Example 9, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 30:70. In Example 10, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 20:80. In Example 11, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 10:90. In Example 12, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 100:0. In Example 13, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 60:40. In Example 14, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 40:60.

[0097] (Comparative Example 3)

[0098] In Comparative Example 3, the volume ratio of blast furnace slag fine powder (GGBF) to fly ash (FA) in the powder was set to a volume ratio outside the range of Examples 2-14. Specifically, in Comparative Example 3, the volume ratio of blast furnace slag fine powder (GGBF) to fly ash (FA) in the powder was set to 0:100. Table 3 shows the results of the determination of the materials, proportions, and setting time of the geopolymer composition. The setting time was determined in accordance with JIS A1147. It should be noted that in Table 3, S represents fine aggregate, and in this formulation of the geopolymer compositions of Examples 2-14, blast furnace slag fine aggregate was used in 100% proportions.

[0099] [Table 3]

[0100]

[0101] (Examples 15-27)

[0102] For formulations using coarse aggregate, in Example 15, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 100:0; in Example 16, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 90:10; in Example 17, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to 80:20; and in Example 18, the volume ratio of blast furnace slag powder (GGBF) to fly ash (FA) in the powder is set to... In Example 19, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 60:40. In Example 20, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 50:50. In Example 21, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 40:60. In Example 22, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 30:70. In Example 23, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 20:80. In Example 24, the volume ratio of blast furnace slag micro powder (GGBF) to fly ash (FA) in the powder was set to 10:90. In Example 25, the volume ratio of blast furnace slag micropowder (GGBF) to fly ash (FA) in the powder was set to 100:0. In Example 26, the volume ratio of blast furnace slag micropowder (GGBF) to fly ash (FA) in the powder was set to 60:40. In Example 27, the volume ratio of blast furnace slag micropowder (GGBF) to fly ash (FA) in the powder was set to 40:60. The setting time of the geopolymer composition obtained after mixing was measured. The setting time was measured in accordance with JIS A1147. Table 4 shows the materials, proportions, and setting time results of the geopolymer compositions using coarse aggregate.

[0103] (Comparative Example 4)

[0104] In Comparative Example 4, the volume ratio of blast furnace slag micropowder (GGBF) to fly ash (FA) in the powder was set to a volume ratio outside the range of Examples 15-27 above. Specifically, in Comparative Example 4, the volume ratio of blast furnace slag micropowder (GGBF) to fly ash (FA) in the powder was set to 0:100. Table 4 shows the results of the determination of the materials, proportions, and setting time of the geopolymer composition.

[0105] [Table 4]

[0106]

[0107] According to Tables 3 and 4, the formulations in Comparative Examples 3 and 4 resulted in slow coagulation of the polymer compositions, with coagulation not completed within one day. Therefore, it can be concluded that the formulations in Examples 2-27, i.e., the use of powders containing blast furnace slag micron powder and fly ash in a particle size of less than 0.1 mm, are ideal.

[0108] (Examples 28-31, Comparative Examples 5-8)

[0109] In Examples 28-31 and Comparative Examples 5-8, geopolymer compositions were prepared by varying the proportion of blast furnace slag fine aggregate in the fine aggregate without using coarse aggregate. These geopolymer compositions were then cured to produce geopolymer cured products, and compounding tests were conducted to investigate the difference in drying shrinkage properties during the manufacture of the geopolymer cured products. In Examples 28-31, the volume proportion of blast furnace slag fine aggregate in the fine aggregate composed of blast furnace slag fine aggregate and crushed sand was set to 50-100%. In Comparative Examples 5-8, the volume proportion of blast furnace slag fine aggregate in the fine aggregate composed of blast furnace slag fine aggregate and crushed sand was set to 0-45%. The results of the geopolymer composition compounding and the drying shrinkage tests calculated based on the polymer composition and the cured geopolymer products are shown in Table 5. The drying shrinkage tests were conducted using a method based on the length change determination method for mortar and concrete specified in JIS A1129-3:2010.

[0110] [Table 5]

[0111]

[0112] (Examples 32-35, Comparative Examples 9-12)

[0113] In Examples 32-35, geopolymer compositions were prepared by varying the proportion of blast furnace slag fine aggregate in the fine aggregate when using coarse aggregate. These compositions were then cured to produce geopolymer cured products, and compounding tests were conducted to investigate the difference in drying shrinkage properties during the production of the cured products. In Examples 32-35, the volume proportion of blast furnace slag fine aggregate in the fine aggregate composed of blast furnace slag fine aggregate and crushed sand was set to 50-100%. In Comparative Examples 9-12, the volume proportion of blast furnace slag fine aggregate in the fine aggregate composed of blast furnace slag fine aggregate and crushed sand was set to 0-45%. The compounding of the geopolymer compositions and the results of the drying shrinkage tests calculated based on the geopolymer compositions and the cured geopolymer products are shown in Table 6.

[0114] [Table 6]

[0115]

[0116] As shown in Tables 5 and 6, when the proportion of blast furnace slag fine aggregate in the fine aggregate is 50% by volume or more, the drying shrinkage of the geopolymer composition can be significantly reduced. Thus, in the above embodiments, an example is shown of manufacturing a geopolymer cured product by curing a geopolymer composition containing a powder comprising blast furnace slag micropowder (GGBF) and fly ash (FA) in a volume ratio of 40:60 and a fine aggregate comprising 50% by volume or more of blast furnace slag fine aggregate.

[0117] Furthermore, from another perspective, the geopolymer solidified product manufactured by the method of the present invention uses a geopolymer composition containing fly ash, a byproduct of thermal power generation, and blast furnace slag powder, a byproduct of molten iron production. Therefore, since the method of manufacturing the geopolymer solidified product of the present invention does not use the fine aggregates commonly used in geopolymers, it does not harm nature and is useful as a method for obtaining more environmentally friendly geopolymer solidified products.

[0118] Industrial availability

[0119] The method for manufacturing geopolymer solidified products of the present invention can improve the flowability and fresh mixing properties of geopolymer compositions used as precursors for geopolymer solidified products, and can produce geopolymer solidified products with significantly reduced drying shrinkage. Therefore, the method for manufacturing geopolymer solidified products of the present invention is of industrial use and contributes to the development of industries such as civil engineering and construction, materials industry, and environmental industry.

Claims

1. A method for manufacturing geopolymer solidified products, characterized in that, include: The first step of manufacturing a geopolymer composition by mixing aggregates containing fine blast furnace slag aggregates, powders containing micro-powdered blast furnace slag, alkali metal solution, gluconic acid, and water; and A second step involves curing the geopolymer composition manufactured in the first step. As fine aggregate in the aggregate, the fine aggregate contains more than 50% by volume of the blast furnace slag fine aggregate.

2. The method for manufacturing geopolymer solidified material as described in claim 1, characterized in that, The powder contains the fly ash in a volume ratio of 10:90 to 100:0, based on the volume ratio of the blast furnace slag micro powder to fly ash.

3. A geopolymer solidified product manufactured by the method for manufacturing geopolymer solidified products according to claim 1 or 2.

4. A method for manufacturing a geopolymer composition, wherein, Geopolymer compositions are prepared by mixing aggregates containing fine blast furnace slag aggregates, powders containing micro-powdered blast furnace slag, alkali metal solutions, gluconic acid, and water. As fine aggregate in the aggregate, the fine aggregate contains more than 50% by volume of the blast furnace slag fine aggregate.

5. A geopolymer composition manufactured by the method of manufacturing the geopolymer composition according to claim 4.

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