WO2026018732A1 - Geopolymer starting material composition, method for producing same, and method for producing geopolymer composition - Google Patents

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

The present invention relates to a geopolymer raw material composition used in the construction and repair of structures in civil engineering, architecture, etc., a method for producing the same, and a method for producing a geopolymer composition.

Traditionally, structures in civil engineering, architecture, etc. have generally been made from concrete or mortar, but in recent years, geopolymer compositions have been attracting attention as an alternative material to concrete and mortar, and their application to various structures as geopolymer concrete is being considered (see, for example, Patent Document 1).

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, and silica fume with an alkaline solution and then subjecting it to a dehydration condensation polymerization reaction. By further adding fine aggregate, coarse aggregate, etc., a composition is achieved that exhibits strength equivalent to that of cement concrete.

One method of manufacturing 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 desired location (such as a formwork). Another method involves adding an alkaline aqueous solution or water to a mixture of activated filler and alkaline powder (a premix), kneading the mixture, and then pouring the mixture into the desired location (such as a formwork).

On the other hand, there is a method that does not involve the mixing and kneading of raw materials, but rather involves spraying powder and liquid raw materials onto the target area (such as a wall surface) and allowing them to harden in place, such as dry spraying.

Patent No. 5091519

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 poorly transportable in powder form. For this reason, for example, when supplying powder raw materials to the construction site by air pressure, it is difficult to maintain a constant supply of powder.

Furthermore, in manufacturing methods that involve mixing and kneading raw materials, the high viscosity of the geopolymer after kneading poses an issue. For example, in the manufacturing process of geopolymer compositions, it is common to use a mixer or other device to knead the raw materials, but the high viscosity of the geopolymer slurry means that the materials may not be mixed uniformly. In order to consistently achieve the specified performance of a geopolymer composition, it is necessary to always mix the raw materials uniformly. Furthermore, if the reduced transportability caused by the high viscosity of the geopolymer slurry after kneading can be improved, workability can also be expected to improve.

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. One way to reduce the water content is to add a water reducer or dispersant, as with conventional cement, but this requires the development of a water reducer or dispersant specifically for geopolymers, and the addition of the water reducer or dispersant increases costs.

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

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a geopolymer raw material composition, a method for producing the same, and a method for producing a geopolymer composition that can improve the metering and transportability of raw materials, reduce the viscosity of the slurry, and suppress the generation of dust.

In order to achieve the above-mentioned objective, 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.

Furthermore, in order to achieve the above-mentioned objective, the method for producing a geopolymer raw material composition of the present invention is a method for producing a geopolymer raw material composition by granulating some or all of the powdered raw materials of the geopolymer composition, and 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 produce granules.

Furthermore, the method for producing a geopolymer composition of the present invention uses the geopolymer raw material composition, and produces a geopolymer composition by adding water or an alkaline solution to the geopolymer raw material composition and hardening it.

As a result, a geopolymer raw material composition is used in which some or all of the powder raw materials have been granulated, which increases the particle size, improving the raw material's measurability and transportability, while also suppressing dust generation. Furthermore, by increasing the particle size through granulation, the specific surface area relative to the powder decreases, which reduces the amount of water required during mixing and kneading, and reduces the viscosity of the slurry.

According to the present invention, the ability to measure raw materials can be improved, thereby suppressing changes in the raw material blend ratio and improving the stability of the geopolymer composition's performance. In this case, since there is no need to measure multiple types of raw materials individually, the measuring process can be made more efficient and the risk of performance degradation due to measuring errors can be reduced. Furthermore, the transportability of raw materials can be improved, enabling mass transportation of raw materials, for example, in dry spraying construction, 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 raw materials can be homogenized in the premix material. Furthermore, dust generation can be significantly reduced, thereby improving visibility during construction, for example, dry spraying, and reducing the impact of dust on the surrounding environment. Additionally, changes in the blending ratio of the remaining raw materials due to scattering of the raw materials can be suppressed, allowing dry sprayed products to be produced with the correct blending ratio at all times.

FIG. 1 is a diagram showing a manufacturing process of a geopolymer raw material composition according to a first embodiment of the present invention. FIG. 10 is a diagram showing the manufacturing process of a geopolymer raw material composition in a second embodiment of the present invention. Enlarged photograph of granulated product (Example 1) Enlarged photograph of granulated product (Example 2) Enlarged photograph of granulated product (Example 3) Diagram showing the results of the compressive strength test

Figure 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.

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

The geopolymer raw material composition of this embodiment is composed of an active filler, a weakly active or inactive powder, an inorganic alkaline powder raw material that activates the active filler, and the like, such as amorphous powders containing aluminum oxide and silicon oxide, such as fly ash (coal ash), metakaolin, blast furnace slag, volcanic ash, volcanic mud, and sewage sludge incineration ash, silica fume, alkaline powder, calcium carbonate fine powder, silica sand, and blasting material waste, and one or more of these raw materials are used.

Activated fillers are powders that harden through a dehydration condensation polymerization reaction in the presence of alkaline raw materials, such as fly ash (coal ash), metakaolin, blast furnace slag, and silica fume.

The alkaline powder may be, for example, one or more of the following powders: sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, and sodium phosphate.

In addition, in this embodiment, the geopolymer raw material composition is granulated using the so-called spray-drying granulation method, in which a slurry obtained by mixing the powder raw material with at least one of water, an alkaline solution, and a binder is sprayed into hot air and instantly dried to form granules. The binder is a substance used to impart appropriate cohesiveness to the powder raw material during the granulation process, and as a binding medium between solid particles, taking into consideration factors such as strength (disintegrability), solubility, and reactivity depending on the application and purpose.

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

Next, this slurry is placed in a spray dryer (S3) and sprayed into hot air at a predetermined temperature (180°C to 550°C) (S4). This causes the sprayed slurry to instantly dry and be granulated into cornerless spheres (S5), yielding a granular geopolymer raw material composition.

In addition, in this embodiment, the binder used in the granulation process is an inorganic alkaline material (sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, sodium phosphate, etc.) that can be used as a raw material for the geopolymer raw material composition. In other words, because inorganic alkaline materials themselves have the ability (viscosity) to aggregate the powder raw materials, granulation is possible without using an organic binder consisting of other components.

When the geopolymer raw material composition is used to produce a geopolymer composition such as geopolymer concrete, for example, the geopolymer raw material composition is mixed with water or an alkaline solution and kneaded, and then pressure-fed and poured into the desired location (formwork, etc.) at a construction site or factory facility, the geopolymer raw material composition is granulated into spherical shapes. This means that the fluidity after mixing is higher than when powdered raw materials are used in their conventional powder form, and the composition flows smoothly without clogging in pressure-fed pipelines.

Furthermore, when multiple types of powders are mixed, differences in density, size, and shape generally result in imbalances. For example, this can lead to uneven component content in the premix, which can result in variations in the quality of the geopolymer composition after mixing. In the geopolymer raw material composition of this embodiment, multiple types of powder raw materials are mixed and granulated, resulting in particles containing a specified amount of each component. This allows multiple types of raw materials to be mixed uniformly, making it possible to produce a stable geopolymer composition.

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. In addition, when the powdered raw materials are turned into granular masses, the inner raw materials are coated by the binder and the raw materials placed on the surface, which significantly reduces contact between the highly water-absorbent powdered raw materials and the outside, improving their effectiveness in preventing deterioration due to moisture absorption and their fluidity.

Furthermore, even when the geopolymer raw material composition is sprayed directly onto the target area using air pressure, as in dry spraying, the granular geopolymer raw material composition has low cohesiveness, resulting in high fluidity when air pressure fed. Furthermore, the increased particle size caused by granulation prevents the composition from scattering into powder, significantly reducing the amount of dust generated during spraying operations. Furthermore, because the granules are spherical, they exert less impact on the transport rubber hose and spray nozzle, reducing wear and extending their lifespan.

As such, 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.

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

Furthermore, by granulating the material into granules with a particle size larger than that of the powder, the specific surface area can be reduced compared to the powder, and the amount of water required during 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.

Furthermore, by increasing the particle size through granulation and thereby reducing the specific surface area, the effects of humidity on the premix material can be reduced, and by combining multiple powders of different densities into granules, the raw materials in the premix material can be made more uniform. Furthermore, the improved kneadability achieved through granulation can also improve the quality of on-site construction using the premix material.

Furthermore, since dust generation can be suppressed during dry spraying work, the reduced visibility caused by dust can be improved. This is not limited to manned work, but also makes it possible to carry out work remotely while visually checking with a camera, for example. It also reduces the impact of dust on the surrounding environment. Furthermore, since it is possible to suppress changes in the blend ratio of remaining raw materials due to scattering of raw materials, it is possible to always produce dry sprayed products with the correct blend, and dry spraying work makes it possible to transport large quantities of raw materials, improving productivity.

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 it is preferable that the average particle size of the geopolymer raw material composition be 10 μm or more.

Furthermore, the powdered raw material is mixed with at least one of water, an alkaline solution, and a binder to produce a slurry, which is then sprayed into hot air and instantly dried to produce granules. This allows for consistent quality due to a uniform particle size distribution, and the high-speed drying enables granulation in a short period of time, preventing deterioration of the geopolymer raw material composition and improving productivity.

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

In this case, if the hot air temperature is too low, drying will be insufficient, resulting in a decrease in quality and a longer drying time, while if the hot air temperature is too high, the heat will cause deterioration of the geopolymer raw material composition and energy will be wasted, so the hot air temperature should preferably be between 180°C and 550°C.

Furthermore, because the binder used is an inorganic alkaline material that can be used as a raw material for geopolymer compositions, granulation is possible without using organic binders made from other components. This eliminates the need to add new types of binder material, and does not increase material costs or formulation for granulation, making it possible to produce geopolymer raw material compositions at low cost and with high productivity.

In this case, if the ratio of binder to powder raw material is too high, 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 should preferably be between 0.2% and 20%.

Furthermore, if the ratio of water to powder raw material is too high, the drying time will be longer and the particle size distribution will become uneven, while if the water ratio is too low, poor atomization, poor particle shape, and clogging of the spray nozzle will occur, so the ratio of water to powder raw material should preferably be between 40% and 200%.

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, an organic binder may be used, for example, if you want to reduce the amount of alkaline components contained in the granulated material or increase the particle bonding strength.

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

Figure 2 shows a second embodiment of the present invention, in which the granulation process of the previous embodiment is supplemented with a process of crushing or pulverizing the powdered raw material to make it finer.

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, but the activity of these powdered raw materials can be increased by reducing their size by crushing or grinding.

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

In this way, according to this embodiment, at least a portion of the powdered raw materials is pulverized or crushed to a fine powder and then granulated, which makes it possible to increase the activity of weakly active raw materials and expand 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.

In addition, the water used in the crushing or pulverization process can be used for granulation while still containing the raw materials, allowing for efficient production even when using weakly active or inactive raw materials.

In the second embodiment, a raw material with low activity is pulverized to make it finer, but the active filler may also be pulverized or crushed to further increase its activity.

In addition, the first and second embodiments described above use the so-called spray-drying granulation method, 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 multiple openings and cut into granules to form granules; a tumbling granulation method in which powdered raw materials are tumbling in a rotating drum or tumbling pan while being sprayed with a binder or water to form granules; an agitation granulation method in which powdered raw materials are agitated with a rotating blade while being granulated by adding a binder or water; and a fluidized bed granulation method in which the powder is fluidized and a binder or water is sprayed on to bond the particles.

Examples 1 to 3 of the present invention are shown below. Note that the present invention is not limited to these examples.

[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.

[Ratio of ingredients]
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 %.

In Example 2, the total amount of powdered raw materials was 400 kg, the binder was 2 kg, and the water was 316 kg. This resulted in a binder ratio of 0.5% by weight to the powdered raw materials, and a water ratio of 79% by weight to the powdered raw materials.

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. This resulted in a binder ratio of 2% by weight to the powdered raw materials, and a water ratio of 74% by weight to the powdered raw materials.

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

[Granulation]
In Examples 1 to 3, a granulation operation was carried out by spray drying, in which the powder raw material was sprayed into hot air and dried, resulting in the production of granular granules shown in Figures 3 to 5 (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.

As a result of granulation, the granulated products of Examples 1 to 3 all had an average particle size of 10 μm or more. Furthermore, Examples 2 and 3 were carried out using powder raw materials with a total weight of 400 kg, and all were granulated well, confirming that mass production is possible.

[Compression strength test]
6 shows the results of a compressive strength test. A compressive strength test was conducted on Example 1 under room temperature curing conditions (material age: 14 days), resulting in a compressive strength of 47.4 MPa. Comparative Example 1, in which an alkaline aqueous solution was added to a powder raw material with the same composition as Example 1 and mixed, had low fluidity, making it impossible to prepare a uniform specimen, and the compressive strength was only 22.3 MPa.

Claims (10)

A geopolymer raw material composition characterized by being obtained by granulating some or all of the powder raw materials of a geopolymer composition. The geopolymer raw material composition according to claim 1, characterized in that the average particle size is 10 μm or more. A method for producing a geopolymer raw material composition obtained by granulating some or all of the powder raw materials of the geopolymer composition,
A method for producing a geopolymer raw material composition, characterized in that a slurry obtained by mixing at least one of water, an alkaline solution, and a binder with the powder raw material is sprayed into hot air and instantly dried to granulate. The method for producing a geopolymer raw material composition according to claim 3, characterized in that the temperature of the hot air is 180 ° C or more and 550 ° C or less. The 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. 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. 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. 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. 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. Using the geopolymer raw material composition according to claim 1 or 2,
A method for producing a geopolymer composition, comprising adding water or an alkaline solution to a geopolymer raw material composition to harden the composition, thereby producing a geopolymer composition.