Geopolymer starting material composition, method for producing same, and method for producing geopolymer composition

Abstract

The present invention provides: a geopolymer starting material composition which is capable of improving weighing properties and transportability of a starting material, is capable of having a reduced viscosity in the form of a slurry, and is capable of suppressing generation of dust; a method for producing the geopolymer starting material composition; and a method for producing a geopolymer composition.　Since a geopolymer starting material composition in which some or all of a powder starting material is granulated into a granular shape is used, the weighing properties and transportability of the starting material are improved by the increase of the particle diameter, and the generation of dust is suppressed. In addition, since the specific surface area is reduced with respect to the powder by increasing the particle diameter by means of granulation, the amount of water required at the time of mixing and kneading can be reduced, and the viscosity of the slurry is lowered.

Description

Geopolymer raw material composition and method for producing the same, and method for producing geopolymer composition

[0001] The present invention relates to a geopolymer raw material composition used for construction and repair of structures in civil engineering, architecture, etc., a manufacturing method thereof, and a manufacturing method of a geopolymer composition.

[0002] Conventionally, structures in civil engineering, architecture, etc. have generally been formed from concrete or mortar. However, in recent years, geopolymer compositions have been attracting attention as alternative materials to concrete and mortar, and their application to various structures as geopolymer concrete has been considered (see, for example, Patent Document 1).

[0003] Geopolymer composition is a hardened substance obtained by mixing alkali-active amorphous powder (active filler) such as fly ash (coal ash), metakaolin, blast furnace slag, silica fume, etc. with an alkaline solution and then subjecting it to a dehydration condensation polymerization reaction. By further adding fine aggregate, coarse aggregate, etc., a composition that exhibits strength equivalent to that of cement concrete is realized.

[0004] One method for producing geopolymers is to mix and knead an activated filler with an alkaline aqueous solution such as water glass or an alkaline powder such as sodium hydroxide and water, and then pour the mixture into the target area (formwork, etc.).Another method is to add an alkaline aqueous solution or water to a premix of activated filler and alkaline powder, knead it, and then pour the mixture into the target area (formwork, etc.).

[0005] On the other hand, there is a method in which the powder raw material and the liquid raw material are sprayed onto the target location (wall surface, etc.) and then hardened as is, for example, as in dry spraying, without the step of mixing and kneading the raw materials.

[0006] Patent No. 5091519

[0007] However, metakaolin, silica fume, and other powder materials used as geopolymer powder raw materials have extremely small particle sizes and high cohesion, making them difficult to measure accurately and making them difficult to transport. For this reason, when supplying powder raw materials to a construction site by pneumatic transport, it is difficult to maintain a constant supply of powder.

[0008] Furthermore, in manufacturing methods involving the mixing and kneading of raw materials, the high viscosity of the resulting geopolymer is an issue. For example, in the manufacturing process of geopolymer compositions, mixers are typically used to mix the raw materials, but the high viscosity of the geopolymer slurry can sometimes prevent uniform mixing. In order to consistently achieve the desired performance of a geopolymer composition, it is necessary to consistently mix the raw materials uniformly. Furthermore, if the reduced transportability caused by the high viscosity of the geopolymer slurry after mixing can be improved, workability can also be expected to improve.

[0009] Furthermore, when mixing powdered raw materials with water, if the viscosity of the slurry is high, it is expected that the water content will be increased from the perspective of transportability. However, increasing the water content will affect the mix ratio and make it impossible to achieve the required performance. Therefore, one method of reducing the water content is to add water reducers and dispersants, as with conventional cement. However, this requires the development of water reducers and dispersants specifically for geopolymers, and the addition of these agents increases costs.

[0010] Furthermore, in manufacturing methods that do not involve mixing or kneading, dust generation due to the fine powder of the active filler is an issue. For example, in dry spraying construction, issues include reduced visibility due to dust during spraying work, instability of the blending ratio due to scattering of powder raw materials, and impact on the surrounding environment.

[0011] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a geopolymer raw material composition and a manufacturing method thereof, which can improve the measurability and transportability of raw materials, reduce the viscosity of the slurry, and suppress the generation of dust. It is to provide a method for manufacturing a geopolymer composition.

[0012] In order to achieve the above object, the geopolymer raw material composition of the present invention is obtained by granulating some or all of the powder raw materials of the geopolymer composition.

[0013] In addition, in order to achieve the above-mentioned object, the manufacturing method of the geopolymer raw material composition of the present invention is a manufacturing method of a geopolymer raw material composition that is obtained by granulating some or all of the powder raw materials of the geopolymer composition, and the powder raw materials are mixed with at least one of water, an alkaline solution, and a binder. The slurry obtained is sprayed into hot air and instantly dried to granulate.

[0014] In addition, the method for producing a geopolymer composition of the present invention uses the geopolymer raw material composition, adds water or an alkaline solution to the geopolymer raw material composition, and hardens it to produce a geopolymer composition.

[0015] This allows the use of a geopolymer raw material composition in which some or all of the powder raw materials are granulated, which improves the metering and transportability of the raw materials and suppresses dust generation. In addition, by increasing the particle size through granulation, the specific surface area relative to the powder decreases, which reduces the amount of water required for mixing and kneading, and reduces the viscosity of the slurry.

[0016] According to the present invention, the metering of raw materials can be improved, thereby suppressing changes in the raw material blending ratio and improving the stability of the performance of geopolymer compositions. In this case, since there is no need to individually measure multiple types of raw materials, the metering process can be made more efficient and the risk of performance degradation due to metering errors can be reduced. Furthermore, the transportability of raw materials can be improved, enabling mass transportation of raw materials, for example, in dry spraying applications, thereby improving productivity. Furthermore, the viscosity of the slurry can be reduced, thereby increasing the strength and durability of the geopolymer composition (improving acid resistance and salt damage resistance) and reducing viscosity without the use of additives such as water reducers. Furthermore, by increasing the particle size through granulation, the specific surface area can be reduced, thereby reducing the impact of humidity on the premix material. Furthermore, by granulating multiple powders with different densities, the integration of the powders can be achieved, thereby achieving uniformity of the raw materials in the premix material. Furthermore, dust generation can be significantly reduced, thereby improving visibility during dry spraying applications, for example, and reducing the impact of dust on the surrounding environment. Furthermore, since it is possible to suppress changes in the blending ratio of the remaining raw materials due to scattering of the raw materials, it is possible to always produce dry sprayed products with the appropriate blending ratio.

[0017] A diagram showing the manufacturing process of a geopolymer raw material composition in the first embodiment of the present invention. A diagram showing the manufacturing process of a geopolymer raw material composition in the second embodiment of the present invention. A magnified photograph of the granulated material (Example 1). A magnified photograph of the granulated material (Example 2). A magnified photograph of the granulated material (Example 3). A diagram showing the results of a compressive strength test.

[0018] FIG. 1 shows a first embodiment of the present invention, which shows a geopolymer composition used in the construction of structures such as civil engineering and architectural structures.

[0019] The geopolymer composition of this embodiment is produced by adding water or an alkaline solution to a geopolymer raw material composition obtained by granulating some or all of the powder raw material into granules and hardening the composition. In addition to water or an alkaline solution, aggregates (fine aggregates such as sand or coarse aggregates such as gravel) and other materials may also be added.

[0020] The geopolymer raw material composition of this embodiment is composed of an active filler, a powder with weak activity or inactivity, an inorganic alkaline powder raw material that activates the active filler, and the like. For example, fly ash (coal ash), metakaolin, blast furnace slag, volcanic ash, volcanic mud, sewage sludge incineration ash, etc. It consists of amorphous powder containing aluminum oxide and silicon oxide, silica fume, alkali powder, calcium carbonate fine powder, silica sand, blast material waste, etc., and one or more of these raw materials are used.

[0021] The active filler is a powder that hardens by dehydration condensation polymerization reaction with an alkaline raw material, and examples thereof include fly ash (coal ash), metakaolin, blast furnace slag, and silica fume.

[0022] The alkaline powder may be, for example, one or more of sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, and sodium phosphate.

[0023] In this embodiment, the geopolymer raw material composition is granulated by spraying the resulting slurry into hot air and instantly drying it. This is called spray-drying. The binder is a substance used to provide the powder raw material with appropriate cohesiveness during the granulation process, and acts as a binding medium between solid particles, taking into account factors such as strength (disintegrability), solubility, and reactivity depending on the application and purpose.

[0024] In the granulation process of this embodiment shown in Fig. 1, water and a binder are added to a powder raw material consisting of one or more active fillers and kneaded (S1) to produce a slurry (S2). In this case, the ratio of the binder to the powder raw material is 0.2% to 20%, and the ratio of water to the powder raw material is 40% to 200%.

[0025] Next, the slurry is put into a spray dryer (S3) and sprayed into hot air at a predetermined temperature (180°C to 550°C) (S4). As a result, the sprayed slurry is instantly dried and granulated into spherical shapes without corners (S5), and a granular geopolymer raw material composition is obtained.

[0026] In this embodiment, inorganic alkaline materials (sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, sodium phosphate, etc.) that can be used as raw materials for geopolymer raw material compositions are used as binders in the granulation process. That is, inorganic alkaline materials have the ability to aggregate powder raw materials by themselves (viscosity), making it possible to granulate without using organic binders consisting of other components.

[0027] When producing a geopolymer composition such as geopolymer concrete using the geopolymer raw material composition, for example, by mixing the geopolymer raw material composition with water or an alkaline solution and kneading it, and then pumping it into the desired location (formwork, etc.) at a construction site or in a factory facility, the geopolymer raw material composition is granulated into spherical shapes. This means that the fluidity after mixing is higher than when the powder raw material is used in its original powder form as in the past, and the mixture flows smoothly without clogging in the pumping pipeline.

[0028] In addition, generally, the density, size, and shape of the mixed powders can cause imbalances. For example, the component contents in the premix can become uneven, which can lead to variations in the quality of the mixed geopolymer composition. In the geopolymer raw material composition of this embodiment, multiple types of powder raw materials are mixed and granulated to obtain particles containing a predetermined amount of each component. This allows multiple types of raw materials to be mixed uniformly, making it possible to produce a stable geopolymer composition.

[0029] Furthermore, granulating the raw materials reduces their specific surface area, making it possible to suppress deterioration of the raw material's performance due to moisture absorption, etc. This reduces the amount of water required during mixing or kneading, and also makes it possible to lower the viscosity of the mixture. Furthermore, by forming the powdered raw materials into granular masses, the inner raw materials are coated with the binder and the raw materials placed on the surface, significantly reducing contact of the highly water-absorbent powdered raw materials with the outside, thereby preventing deterioration due to moisture absorption and improving fluidity.

[0030] Furthermore, even when the geopolymer raw material composition is sprayed directly onto the target area by air pressure, as in dry spraying, the granular geopolymer raw material composition has low cohesiveness, resulting in high fluidity during air pressure feeding. Furthermore, the increased particle size due to granulation suppresses powder scattering, significantly reducing the amount of dust generated during spraying work. Furthermore, the spherical shape of the granules reduces impact on the rubber hoses and spray nozzles used for transportation, reducing wear and extending their lifespan.

[0031] Thus, according to the geopolymer raw material composition of this embodiment, some or all of the powder raw materials of the geopolymer composition are granulated into granules, which improves the measurability and transportability of the raw materials, reduces the viscosity of the slurry, and suppresses the generation of dust.

[0032] In other words, by improving the weighing and transportability of raw materials, changes in the blending ratio of raw materials can be suppressed, improving the stability of the performance of the geopolymer composition. In this case, since there is no need to weigh multiple types of raw materials individually, the weighing process can be made more efficient and the risk of performance degradation due to weighing errors can be reduced. Furthermore, since spherical particles can be formed by granulation, the bearing effect also improves fluidity.

[0033] Furthermore, by granulating the material into granules with a particle size larger than that of the powder, the specific surface area can be reduced relative to the powder, and the amount of water required for mixing and kneading can be reduced. This reduces the viscosity of the slurry, making it possible to increase the strength and durability of the geopolymer composition (improving acid resistance and salt damage resistance), and reducing viscosity without the use of additives such as water reducers.

[0034] Furthermore, the effect of humidity on the premix can be reduced by increasing the particle size through granulation, thereby reducing the specific surface area, and the integration of multiple powders with different densities into granules can make the raw materials in the premix uniform. Furthermore, the improved kneadability achieved through granulation can also improve the quality of on-site construction using the premix.

[0035] Furthermore, since the generation of dust can be suppressed during dry spraying, etc., the decrease in visibility due to dust can be improved. This is not limited to manned construction, but also makes it possible to perform remote construction while visually checking with a camera, for example. The impact of dust on the surrounding environment can also be reduced. Furthermore, since changes in the blending ratio of remaining raw materials due to scattering of raw materials can be suppressed, dry sprayed products with the appropriate blending can always be produced, and dry spraying construction makes it possible to transport large quantities of raw materials, improving productivity.

[0036] Furthermore, if the particle size of the geopolymer raw material composition is too small, the effect of increasing the particle size will be reduced, so the average particle size of the geopolymer raw material composition is preferably 10 μm or more.

[0037] Furthermore, the powder raw material is mixed with at least one of water, an alkaline solution, and a binder to obtain a slurry, which is then sprayed into hot air and instantly dried to form granules.This allows for stable quality due to the uniform particle size distribution, and high-speed drying makes it possible to granulate in a short period of time, thereby suppressing deterioration of the geopolymer raw material composition and improving productivity.

[0038] Furthermore, particle size can be controlled by adjusting conditions such as drying temperature, wind speed, and atomization method. This makes it possible to adjust the usable time according to the particle size and binder ratio, for example, or to achieve closest packing by mixing raw materials of different particle sizes, thereby improving strength and reducing shrinkage.

[0039] In this case, if the temperature of the hot air is too low, the drying will be insufficient, resulting in a decrease in quality and a longer drying time, and if the temperature of the hot air is too high, the geopolymer raw material composition will be altered by the heat and energy will be wasted. Therefore, the temperature of the hot air is preferably 180°C or higher and 550°C or lower.

[0040] Furthermore, because the binder is an inorganic alkaline material that can be used as a raw material for geopolymer compositions, granulation is possible without using organic binders composed of other components. This eliminates the need to add additional types of binder material, and does not increase the material costs or formulation for granulation, allowing for the production of geopolymer raw material compositions at low cost and with high productivity.

[0041] In this case, if the ratio of binder to powder raw material is too high, the solubility will decrease, and if the ratio is too low, the particle bonding strength will be insufficient and uniformity will decrease, so the ratio of binder to powder raw material is preferably 0.2% or more and 20% or less.

[0042] Furthermore, if the ratio of water to the powder raw material is too high, the drying time will be long and the particle size distribution will become non-uniform, while if the ratio of water is too low, poor atomization, poor particle shape, clogging of the spray nozzle, etc. will occur. Therefore, the ratio of water to the powder raw material is preferably 40% or more and 200% or less.

[0043] In the above embodiment, an inorganic alkaline material that can be used as a raw material for the geopolymer composition is used as the binder. However, for example, if you want to reduce the amount of alkaline components contained in the granulated material or if you want to increase the particle bonding strength, you may use an organic binder.

[0044] In the above embodiment, water is added to the powder raw material containing alkaline powder to form granules, but alkaline waste liquid may be used instead of some or all of the alkaline powder and water. Alkaline waste liquid is a high-pH (alkaline) waste liquid generated after use, for example, in metal cleaning or surface treatment, and can be generated in many industrial fields. Therefore, using such alkaline waste liquid instead of expensive alkali has the advantage of reducing the production cost of the geopolymer raw material composition and also recycling industrial waste.

[0045] FIG. 2 shows a second embodiment of the present invention, in which a step of crushing or pulverizing the powder raw material to make it finer is added to the granulation step of the previous embodiment.

[0046] Among powdered raw materials, for example, fly ash (coal ash), volcanic ash such as Shirasu, volcanic mud, and sewage sludge incineration ash have low activity and cannot be used alone as raw materials for geopolymer compositions. However, the activity of these powdered raw materials can be increased by pulverizing or grinding them into fine particles.

[0047] This embodiment includes a process for crushing or pulverizing the weakly activated powder raw material described above. Specifically, in the granulation process of this embodiment, as shown in Figure 2, the powder raw material and water are first mixed (S10), and then crushed using a known ball mill or the like (S11). Next, a binder is added to the crushed powder raw material and water, and the mixture is kneaded (S12) to produce a slurry (S13). One or more active fillers may be added as other powder raw materials, or the amount of water may be increased. Next, as in the first embodiment, the slurry is loaded into a spray dryer (S14) and sprayed into hot air at a predetermined temperature (180°C to 550°C) (S15). The sprayed slurry is instantly dried and granulated into cornerless spherical shapes (S16), resulting in a granular geopolymer raw material composition.

[0048] Thus, according to this embodiment, at least a portion of the powdered raw materials is pulverized or crushed to form fine particles, thereby increasing the activity of weakly active raw materials and broadening the range of raw materials that can be used as raw materials for geopolymer compositions. In particular, fly ash (coal ash), volcanic ash, volcanic mud, etc. are inexpensive materials, so by increasing the content of these raw materials, the overall manufacturing cost of the geopolymer composition can be reduced.

[0049] Furthermore, since the water used in the crushing or pulverizing treatment can be used for granulation while still containing the raw material, efficient production is possible even when using a weakly active or inactive raw material.

[0050] In the second embodiment, a raw material having a weak activity is pulverized to make it finer, but the activity of the active filler may be increased by pulverizing or crushing it.

[0051] Furthermore, in the first and second embodiments, the so-called spray-drying granulation method is used, in which a slurry of raw materials is sprayed into hot air and dried. However, other granulation methods may also be used, such as an extrusion granulation method in which the slurry is extruded through a plurality of openings and cut into granules to form granules; a tumbling granulation method in which a powdered raw material is tumbling in a rotating drum or tumbling pan while a binder or water is sprayed onto it to form granules; an agitation granulation method in which a powdered raw material is agitated with a rotating blade while a binder or water is added to form granules; and a fluidized bed granulation method in which the powder is fluidized and a binder or water is sprayed onto it to bond the particles.

[0052] Examples 1 to 3 of the present invention will be described below, but the present invention is not limited to these examples.

[0053] [Raw materials used] The geopolymer compositions of Examples 1 to 3 used fly ash, metakaolin, and silica fume as powder raw materials, and a sodium silicate aqueous solution as a binder.

[0054] [Ratio of Raw Materials] In Example 1, the total weight of the powder raw materials was 1 kg, the binder was 0.02 kg, and the water was 1 kg. As a result, the ratio of the binder to the powder raw materials was 2 wt %, and the ratio of the water to the powder raw materials was 100 wt %.

[0055] In Example 2, the total amount of powdered raw materials was 400 kg, the amount of binder was 2 kg, and the amount of water was 316 kg. As a result, the ratio of binder to powdered raw materials was 0.5 wt %, and the ratio of water to powdered raw materials was 79 wt %.

[0056] In Example 3, the total weight of the powdered raw materials was 400 kg, the binder was 8 kg, and the water was 295 kg. As a result, the ratio of the binder to the powdered raw materials was 2 wt %, and the ratio of the water to the powdered raw materials was 74 wt %.

[0057] In each of Examples 1 to 3, the mass of the solid component in the aqueous sodium silicate solution used as a binder was taken as the mass of the binder, and the mass of the water in the aqueous sodium silicate solution was included in the mass of water.

[0058]

[0059] [Granulation] In Examples 1 to 3, a granulation operation was carried out by spraying the powder raw material into hot air and drying it by a spray drying method, and as a result, granular granules shown in Figures 3 to 5 were produced (Figure 3 is Example 1, Figure 4 is Example 2, and Figure 5 is Example 3). In this case, the hot air temperature was 200°C in Example 1 and 500°C in Examples 2 and 3.

[0060] As a result of granulation, the average particle size of the granulated products in Examples 1 to 3 was 10 μm or more. In Examples 2 and 3, the total weight of the powder raw material was 400 kg, and all of the granulated products were well granulated, confirming that mass production is possible.

[0061] [Compressive Strength Test] Fig. 6 shows the results of the compressive strength test. When a compressive strength test was conducted on Example 1 under the condition of room temperature curing (material age 14 days), a compressive strength of 47.4 MPa was obtained. In Comparative Example 1, in which an alkaline aqueous solution was added to a powder raw material having the same composition as Example 1 and mixed, a uniform test specimen could not be prepared due to low fluidity, and the compressive strength was only 22.3 MPa.

Claims

1. A geopolymer raw material composition characterized by being obtained by granulating some or all of the powder raw materials of a geopolymer composition.

2. The geopolymer raw material composition according to claim 1, characterized in that the average particle size is 10 μm or more.

3. A method for producing a geopolymer raw material composition by granulating some or all of the powdered raw materials of a geopolymer composition, characterized in that the powdered raw materials are mixed with at least one of water, an alkaline solution, and a binder to obtain a slurry, which is then sprayed into hot air and instantly dried to granulate the material.

4. The method for producing a geopolymer raw material composition according to claim 3, wherein the temperature of the hot air is 180°C or higher and 550°C or lower.

5. A method for producing a geopolymer raw material composition according to claim 3, characterized in that the binder is an inorganic alkaline material that can be used as a raw material for a geopolymer composition.

6. The method for producing a geopolymer raw material composition according to claim 3, characterized in that the ratio of the binder to the powder raw material is 0.2% or more and 20% or less.

7. The method for producing a geopolymer raw material composition according to claim 3, characterized in that the ratio of water to the powder raw material is 40% or more and 200% or less.

8. The method for producing a geopolymer raw material composition according to claim 3, characterized in that at least a portion of the powder raw material is pulverized or crushed to form fine particles.

9. The method for producing a geopolymer raw material composition according to claim 3, characterized in that alkaline waste liquid is used for part or all of the binder and water.

10. A method for producing a geopolymer composition, comprising using the geopolymer raw material composition according to claim 1 or 2 and adding water or an alkaline solution to the geopolymer raw material composition to harden it, thereby producing a geopolymer composition.

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