JP5066766B2 - Geopolymer high-strength cured product containing calcined kaolin as active filler and method for producing the same - Google Patents

Description

  The present invention provides a high-strength, multi-functional cured body by a geopolymer method, and more specifically, a technique for producing a high-strength cured body by blending a novel active filler.

  In recent living environments, internal condensation has occurred due to improved heat insulation and heating facilities, and the strength of the wall material has been degraded and corroded. In addition, allergic problems have occurred due to the occurrence of mites and molds. is doing.

  For this reason, the development of humidity-control building materials that can provide moisture control functions to the building materials themselves, control the humidity in the room without requiring air-conditioning equipment or electric power, and obtain dew-proof and mold-proof properties. Has been done. Moreover, the development of building materials that absorb and remove such harmful substances due to the problem of sick house syndrome due to the occurrence of VOCs generated from building materials is also expected.

  Such building materials have already been developed, but building materials obtained by hydrothermal treatment and high-temperature firing treatment are mainstream and have problems such as high cost. In addition, there are many materials (humidity control ability is low) such as calcium silicate materials in which pores on the order of nanometers are not formed and the humidity is saturated and the capacity is lowered. Moreover, there are many materials whose manufacturing process is very complicated because of pore control on the nanometer order.

There is a powder curing technique called the geopolymer method.
The geopolymer method is a technique for producing artificial rock by connecting powders by using a condensation polymer of silicic acid as a binder such as glue. A silicate monomer, that is, a sodium silicate aqueous solution (water glass) is mainly used as a polymer source.
When the filler powder comes into contact with water, the metal elutes from the filler itself, particularly in an alkaline solution. In the case of cement, it is similar to the case where calcium is mainly eluted from the clinker mineral, but in the case of geopolymer, aluminum is mainly eluted. Dehydrated kaolin obtained by calcining a clay mineral called kaolin, that is, metakaolin, is a mineral that exhibits remarkable elution. Such a filler with relatively high elution is called an active filler.
Known active fillers include kaolin fillers that elute aluminum, pulverized coal combustion boiler ash (OF ash) and pressurized fluidized bed ash (PF ash) that elute calcium.
When the metal eluted from the active filler comes into contact with water containing a water glass component, the silicate complex is crosslinked and polymerized. This reaction is also observed in many natural phenomena. For example, it is the same reason that the pure sand soil in the landfill is hardened or the dust adhering to the window glass is difficult to remove. The formation mechanism of sedimentary rocks in the crust is exactly a geopolymer reaction, and the origin of the geopolymer comes from this. In the case of cement, water is absorbed, and in the case of geopolymer, water is evaporated.
On the other hand, quartz and hematite have almost no elution and are called inert fillers. In this case, they are not reactive and do not harden forever.

In the case of a calcium-based active filler (which elutes calcium ions), it has a feature that it works and cures at room temperature, but it has a drawback that it takes time for the reaction.
A typical calcium-based active filler is fly ash (OF ash). CaO, which is a basic component, is hydrated to become slaked lime, and calcium ions are eluted and hardened. However, OF ash has a low CaO content and cannot be sufficiently cured.
There is also pressurized fluidized bed ash (PF ash) discharged from power plants that use pressurized fluidized bed boilers. The pressurized fluidized bed boiler has a structure in which massive coal and limestone are mixed at the same time, and circulates and burns gently at a low temperature of around 850 ° C., and SOx reacts with the mixed limestone and does not go out. During circulating combustion, the ash is in a fine powder state and is also recovered as fly ash. This fly ash has an angular appearance without melting because it is burned below the melting point, and does not contain a vitreous substance. For example, hard gypsum (CaSO ₄ ), hydroxy elestatite (Ca ₁₀ (SiO ₄ ) ₃ (SO ₄ ) ₃ (OH) ₂ ), portlandite (Ca (OH) ₂ ), and more calcium ions are eluted than fly ash, resulting in high strength. It is done.
When these calcium-based fillers are used, they have a feature that they can be cured at room temperature, but on the other hand, it takes a very long time to cure.
Therefore, there is the greatest drawback that the shrinkage rate is increased, and this is the greatest disadvantage in producing a functional material such as a humidity control material.
In addition, the calcium-based filler has a smaller amount of Na ions taken into the crystal than the aluminum-based filler (which elutes aluminum ions), so that the Na ions cannot be held excessively, re-eluted, and the strength is deteriorated. It also causes the white flower phenomenon.

The aluminum-based active filler includes metakaolin. Metakaolin is a substance obtained by calcining kaolin and an active filler that elutes aluminum.
Although it is recognized that the amount of elution of this filler increases when heated in a weak alkaline solution, the amount of elution is small.
Therefore, a method of adding strong alkali has been taken.
However, when such a strong alkali is used in relation to ISO (International Organization for Standardization, JIS international version), the use conditions are limited.
Further, when an alkali is used, it is difficult to control the elution rate by adding an alkali, and there is a drawback that it hardens at the time of molding, and there is a problem that a functional material or the like is blended and sufficient strength cannot be expressed. In addition, a large amount of metakaolin must be used, and there is a disadvantage that only a dense cured body can be obtained.
The following technologies are disclosed in the prior patent documents.
In Patent Document 1, PF ash (pressurized fluidized bed boiler ash), OF ash (pulverized coal boiler ash), zeolite powder and No. 1 sodium silicate double water dilution are mixed and molded and cured at room temperature. And curing (see Example 1), metakaolin is treated with an alkali to become an artificial zeolite (paragraphs [0014] and [0018]).

In Patent Document 2, a composition containing a powder obtained by applying mechanical energy to metakaolin, an alkali metal silicate, and water is cured, and then water is added to the powder and gypsum obtained by pulverization. A humidity control building material cured by mixing is described, and metakaolin is obtained by dehydration heating of kaolin mineral at 500 to 900 ° C. (see claims 1-4), and detailed description (paragraph [0014] -[0016]) has the following description, but the heat dehydration temperature is preferably 600 to 800 ° C.
(1) Heat dehydration step In the present invention, if necessary, a heat dehydration step can be performed prior to the step of obtaining the inorganic powder. The heating and dehydrating step is a step of obtaining metakaolin by heating and dehydrating kaolin mineral at 500 to 900 ° C.
The kaolin mineral used in the above step is not particularly limited, and a 1: 1 layered silicate mineral represented by the chemical formula: Al ₂ SiO ₅ (OH) ₄ is used. Specific examples include kaolinite, decanite, nacrite, halloysite, and the like.
The heating temperature used at the said process is 500-900 degreeC, and 600-800 degreeC is preferable. That is, when the heating temperature is less than 500 ° C., the hydroxyl group of the kaolin mineral is not eliminated, so that the transformation into metakaolin does not occur. On the other hand, when the heating temperature exceeds 900 ° C., crystallization occurs and the reactivity with alkali is remarkably lowered, so that the production rate of the zeolite structure by heat curing is lowered.
JP 2005-60175 A JP-A-2005-343751

In order to have a humidity control function and an antifungal function, it is necessary to provide a “breathing building material”. For that purpose, it is necessary to have pores in the order of nanometers, and if the strength is not maintained Don't be. In order to have an adsorption function, it is necessary to prevent deterioration of strength and quality even if functional powder is blended. For that purpose, pore diameter control technology and special curing technology are required. Waste powder can also be used. Moreover, cost reduction is required by a low-temperature curing technique that does not depend on firing.
In view of the above-mentioned problems of the prior art, the object of the invention is to provide a building material having a high moisture absorption / release capacity and excellent humidity control performance used for interior materials and the like by the pore diameter control technology and an efficient manufacturing method thereof. Rather, it is to develop a multifunctional building material such as an adsorption function that accompanies the breathing of materials. Moreover, it is providing the technique which can be applied to various members at low cost.

Therefore, the inventors baked kaolin at various temperatures and thoroughly investigated its elution characteristics.
In the present invention, a silicate monomer is used as a polymer source, a sodium silicate aqueous solution is used, and a novel active filler is blended to produce a high strength cured product. Kaolin is made into a powder that easily elutes aluminum ions at a predetermined temperature, and this is used as a curing material for an alkali silicate solution. Successfully produced.

Kaolin was calcined at each temperature and the elution characteristics were thoroughly investigated. As a result, the optimum calcining range of kaolin was found.
When kaolin is calcined, it becomes an amorphous phase called metakaolin at around 550 ° C. (see FIG. 1). Crystallographically, an amorphous state called metakaolin is maintained from 550 ° C. to 900 ° C. In the sample calcined at 1000 ° C., formation of Al—Si spinel was detected, and in the sample calcined at 1200 ° C., it was confirmed that the spinel changed to mullite and cristobalite.
FIG. 2 shows a result of thermal analysis of kaolin. From the results, it can be seen from the endothermic peak around 530 ° C. whether kaolin changes to an amorphous substance called metakaolin. Also, an exothermic peak was observed at 994 ° C., indicating that metakaolin crystallizes into an Al—Si spinel phase.
It is inferred that the schematic structure of metakaolin is as shown in FIG. In the production of geopolymers, metakaolin baked at 750 ° C. is usually used.

FIG. 4 shows the change in the elution amount per gram (g) depending on the calcining temperature of kaolin.
2 g of kaolin ore and heat-treated calcined kaolin were collected in a 100 ml plastic container, and 50 ml of ultrapure water was added. After stirring using a stirrer, the liquid was separated from the dispersion with a centrifuge to obtain an eluate. The elution ion concentration was measured using an ICP plasma emission spectrometer.
In the elution test at 80 ° C., the elution amount was higher at all calcination temperatures than at 25 ° C., and high elution was observed particularly in the calcination temperature region where metakaolin from 550 ° C. to 800 ° C. was produced.
In the calcined sample at 900 ° C., the elution amount of Al ³⁺ ions increased specifically, rapidly increased, and a peak was observed. And when calcined at 950 ° C. or higher, the amount of elution decreased rapidly.
This rapid increase in the elution amount of Al ³⁺ ions is thought to be due to the instability of the metakaolin structure immediately before the crystal transition from metakaolin to Al—Si spinel.
FIG. 5 shows the results of NMR measurement of aluminum ions. The aluminum atom of metakaolin shows a structure including tetracoordinate, pentacoordinate, and hexacoordinate, but the pentacoordinate is about to disappear after baking at 900 ° C. This indicates that the structure of metakaolin has changed. This structural change is considered to affect the elution characteristics.
In addition, the elution of silica may be considered at 900 ° C. or higher, and there is a possibility that it reacts with aluminum. As a result, aluminum is selectively eluted at 900 ° C. (850 ° C. to 950 ° C.). (950 ° C. is the temperature immediately before spinel formation, and when no alkali is added, the elution of silica decreases and the elution amount of aluminum also increases.)

The following can be inferred from the results of this experiment.
That is, it was inferred that kaolin calcined in a very small temperature range centered on 900 ° C. (850 ° C. to 950 ° C.) (hereinafter referred to as “calcined kaolin”) is very effective as an active filler for geopolymers. . The reason is the following three points.
(1) In the calcined kaolin, the elution amount of aluminum ions remarkably changes with changes in room temperature and high temperature.
Since calcined kaolin strongly depends on the elution amount of aluminum ions depending on the temperature, the elution amount can be controlled by temperature control.
By blending the calcined kaolin, it is possible to produce a molded article with high strength by molding at room temperature and then curing at high temperature.
(2) The amount of aluminum ions eluted from the calcined kaolin is much larger than that of metakaolin.
The calcined kaolin may be incorporated in a small amount as compared with the metakaolin calcined at a low temperature, and it is not necessary to add an alkali. The reaction is complete,
(3) The calcined kaolin becomes porous with a part of the crystal structure of kaolin retained after elution of aluminum ions, and highly active amorphous silica remains.
Various functions can be provided by amorphous silica.

It has been confirmed that when the calcined kaolin of the present invention is used in the geopolymer technology, the performance of the cured product can be dramatically improved without using an alkali as a molding advantage. In addition, unprecedented characteristics could be obtained.
Their characteristics are as follows.
(1) The pore diameter can be controlled.
Silica is difficult to elute, and amorphous silica can remain in the fine pore structure by remaining amorphous silica. This makes it possible to control various pore sizes.
This is because amorphous silica becomes the nucleus of the reaction if reactive ions are present around it, and it becomes possible to generate a fine structure.
That is, the pores of several μm to several hundred μm can be shifted from several nm to several tens of nm from the molding conditions and the blending conditions. Depending on the pressing pressure, the pores can be eliminated.
If the pores are distributed in the range of several nm to several tens of nm, a humidity control material can be obtained.
On the contrary, voids can be increased by excessively producing ettringite.
Thus, the pore distribution can be freely controlled by mixing the raw materials and the calcined kaolin.
(2) A high-strength, non-shrinkable cured body can be obtained.
Next, it was found that the reaction is active, and a non-shrinkable cured product can be obtained by examining the reaction product. By forming a needle-like substance in the fine tissue region. A cured product having high strength and no shrinkage can be obtained.
(3) A large amount of functional material can be blended.
When curing functional powders with conventional geopolymer technology, the biggest drawback is shrinkage. When theolite, diatomaceous earth, sepiolite, and adsorptive functional material are combined, shrinkage and deformation are involved, and sufficient strength is obtained. There wasn't.
(4) By combining with the functions of (1) to (3), the inventors succeeded in maintaining the strength without losing the functions of zeolite, diatomaceous earth, sepiolite, adsorbing functional material and the like.
Outlines of (1) to (3) are shown in FIGS.
The active filler has not only a curing function by polycondensation but also a mechanism for controlling pores and increasing strength.

  That is, since the binder component itself serving as a binder has pores in the nm to several tens of nm region, the cured product containing a large amount of the humidity control material also has pores in the nm to several tens of nm region continuously, It becomes possible to obtain a highly functional humidity conditioning material.

Based on the above examination, the embodiments of the present invention are as follows.
(1) It is obtained by curing a filler obtained by mixing calcined kaolin and gypsum heat-treated at 850 ° C. to 950 ° C. as an active filler, a geopolymer, and water, and curing at a high temperature. Geopolymer high-strength cured product.
(2) The geopolymer high-strength cured product according to (1), wherein PF ash is used as a component of gypsum.
(3) A method for producing a geopolymer high-strength cured product, characterized in that a filler containing calcined kaolin and gypsum as an active filler, a geopolymer and water are mixed, molded, and cured by curing at a high temperature. .
(4) The method for producing a geopolymer high-strength cured product as described in (3) above, wherein PF ash is used as a component of gypsum.
Furthermore, the following deodorizing / humidifying hardened material can be exemplified as another embodiment.
(5) A deodorizing / humidifying cured body characterized by further comprising sepiolite as a filler in the cured body according to (1) or (2).
(6) A deodorized / humidified cured body characterized in that in the cured body according to (1) or (2), sepiolite further treated with calcium chloride is added as a filler.
(7) The cured body according to (1) or (2) above, further comprising diatomaceous earth as a filler.
(8) A moisture-curing cured body according to (1) or (2), wherein silica sol or silica gel is further blended as a filler.
(9) A light-weight moisture-curing cured product according to (1) or (2) , further comprising a wood filler as a filler.
(10) A lightweight heat-insulating and moisture-adjusting cured product according to (9) , wherein a shirasu balloon is further blended as a filler.

(1) A high-strength molded body can be produced by molding at room temperature and then curing at high temperature.
(2) The calcined kaolin may be mixed in a small amount as compared with metakaolin, and it is not necessary to add an alkali. The reaction is complete.
(3) The calcined kaolin becomes porous with a part of the crystal structure of kaolin retained after elution of aluminum ions, and highly active amorphous silica remains.
Various functions can be provided by amorphous silica.
Their characteristics are as follows.
(4) The pore diameter can be controlled.
(5) A high-strength and non-shrinkable cured product is obtained.
(6) A large amount of functional material can be blended.
(7) (4) to (6) can be achieved simultaneously.

In actual production, it is desirable to calcine kaolin at 850 ° C. to 950 ° C. centering on 900 ° C. to selectively elute aluminum ions in an alkaline solution.
Kaolin or a mineral containing kaolin is heated using an oxidizing atmosphere furnace at a heating rate of 1 ° C./min to 100 ° C./min and held at a temperature range of 850 ° C. to 950 ° C. for 30 minutes to 24 hours. desirable. It can also be fired using a kerosene furnace such as a gas furnace or a reduction furnace.
As for the compounding quantity of baking kaolin, it is desirable to mix | blend 1-30 weight part with respect to 100 weight part of all fillers.
Moreover, OF ash and PF ash can be suitably used as other active fillers.

The alkali silicate is preferably blended after preparing an aqueous solution in advance. Sodium silicate, potassium silicate, lithium silicate and the like can be used.
The concentration of the alkali metal silicate in the aqueous solution is not particularly limited, but is preferably 5% or more, and more preferably 10 to 80%. When the concentration is less than 5%, the reactivity with the inorganic powder is lowered. On the other hand, when it exceeds 80%, the viscosity becomes high and molding becomes difficult.
In preparation of the aqueous alkali silicate solution, the alkali metal silicate may be dissolved in water. A 50% solution is usually used. The geopolymer liquid usually has a pH of about 12, but may contain potassium hydroxide or sodium hydroxide solution to increase the solubility of the filler.
The blending amount of the alkali silicate solution is desirably 1 to 100 parts by weight with respect to 100 parts by weight of the total filler (OF ash + PF ash + calcined kaolin + functional filler).

OF ash is a spherical particle, and PF ash is a rugged particle. By blending these two particles, a gap of several μm to several tens of μm necessary for controlling the pore diameter is formed.
Examples of particles such as OF ash include glass balloons, shirasu balloons, fly ash balloons, silica balloons, perlite, and foamed silica. In addition, selection of these fillers is suitably performed according to the usage form of a hardening body.
The particles such as PF ash are not particularly limited. For example, silica sand, silica stone powder, crystalline alumina, alumina, talc, mica, diatomaceous earth, mica, rock powder (shirasu, anti-fluorite, etc.), basalt, feldspar Fillers such as wollastonite, clay, bauxite, etc. can also be used.
As the particle size of these fillers, a combination of about the center particle size (5 μm to 200 μm) is good when obtaining a humidity control material. When used as a simple structure, it is not particularly limited.

The curing reaction proceeds mainly by the reaction between the aluminum ions of the calcined kaolin and the silicic acid monomer of the alkali silicate solution, but the OF ash and PF ash are calcium-based active fillers, and the reaction with calcium ions also proceeds gradually.
In the reaction system of the present invention, in the combination of OF ash and PF ash, the higher the ratio of OF ash, the higher the strength and the greater the number of nanometer pores. On the contrary, when the ratio of PF ash is increased, the strength is decreased but the porosity is increased and the amount of voids is increased. It is considered that gypsum in PF ash promotes the formation of ettringite in the reaction system.

There are sepiolite, diatomaceous earth, zeolite, and silica gel as humidity control materials. In the present invention, the basic composition itself has nanometer-order pores, and even if these humidity control materials are blended, the pores of the entire cured body can be continuously controlled. Can demonstrate enough. Sepiolite, zeolite, and silica gel have an adsorption function and a deodorization function, and have a VOC and odor adsorption function.
Sepiolite and diatomaceous earth are lightweight and can produce building materials with heat insulation performance.
The compounding amount of these functional fillers can be 1 to 80 parts by weight with respect to 100 parts by weight of all fillers (OF ash + PF ash + calcined kaolin + functional filler).
Silica sol can be used by blending with an alkali silicate solution. In this case, the solid content ratio is 1 to 20 parts by weight with respect to 100 parts by weight of the total filler (OF ash + PF ash + calcined kaolin + other fillers). It is desirable that

  When a powder obtained by treating sepiolite with a calcium chloride solution is used as a humidity control function material, the humidity control function of the cured product can be further enhanced. When sepiolite is treated with a calcium chloride solution, not only the response speed is increased, but also the absorption / release characteristics are improved. Sepiolite is immersed in a calcium chloride solution (0.1% to 20%), absorbed, and dried to obtain a calcium chloride solution-treated sepiolite. This powder can produce a cured body in the same manner as untreated sepiolite.

A wood filler containing cellulose can be blended for the purpose of humidity control and weight reduction.
Cellulose and other woody pulverized products themselves have a humidity control function, have a function of connecting inorganic powders, and can further enhance the humidity control function. Further, it is possible to promote weight reduction of the cured body. As the wood filler, cellulose, sawdust, bamboo pulverized products, pulverized products of various used papers, and the like can be used.
The blending ratio of the wood filler is desirably 1 to 50 parts by weight with respect to 100 parts by weight of all fillers (OF ash + PF ash + calcined kaolin + other fillers).

  As the molding method, a casting method, a pressing method, an extrusion molding method, or the like can be used. The press method is the method that can most suppress the shrinkage.

A composition with a small amount of PF ash has a small amount of gypsum component and does not produce ettringite. Therefore, the formation of ettringite is promoted by adding gypsum.
In the case of a small amount of gypsum, there is reinforcement and works to increase the strength. Moreover, when it mix | blends abundantly, the amount of voids can be increased. As the gypsum, any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used.

  The humidity control building material of the present invention may contain colorants such as pigments and dyes. The blending amount of the coloring material is arbitrary as long as it does not impair the strength of the building material.

Next, the present invention will be specifically described based on examples. The present invention is not limited to the examples.
[Baking kaolin]
The calcined kaolin that is the active filler used was calcined by the following method.
The calcined kaolin was heated at 10 ° C./min using an oxidation calcining furnace, held at 900 ° C. for 5 hours, and then cooled in the furnace.
[Example 1]
The mixed powder of OF ash: PF ash = 9: 1 was mixed with 5% by weight of calcined kaolin baked at 900 ° C. with respect to the mixed powder. Thereafter, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was blended in 30% by weight with respect to the powder, adjusted for moisture, press-molded at 50 kgf / cm ² , and steamed at 60 ° C. for 24 hours. After curing, it was dried at 105 ° C. for 24 hours.
[Example 2]
The mixed powder of OF ash: PF ash = 7: 3 was mixed with 5% by weight of calcined kaolin baked at 900 ° C. with respect to the mixed powder. Thereafter, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was blended at 30% by weight with respect to the powder, adjusted for moisture, press-molded at 50 kgf / cm ² , and steamed at 60 ° C. for 24 hours. Cured.

Example 3
The mixed powder of OF ash: PF ash = 5: 5 was mixed with 5% by weight of calcined kaolin fired at 900 ° C. with respect to the mixed powder. Thereafter, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was blended in 30% by weight with respect to the powder, adjusted for moisture, press-molded at 50 kgf / cm ² , and steamed at 60 ° C. for 24 hours. Cured.
Example 4
With respect to the mixed powder of (OF ash: PF ash = 9: 1) and sepiolite (sepiolite content 30% by weight), 5% by weight of calcined kaolin baked at 900 ° C. was blended with respect to the mixed powder. After that, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was added to the powder in an amount of 30% by weight, adjusted for moisture, press-molded at 50 kgf / cm ² , and steam cured at 60 ° C. for 24 hours. And then dried at 105 ° C. for 24 hours.
Example 5
With respect to the mixed powder of (OF ash: PF ash = 7: 3) and sepiolite (sepiolite content 30% by weight), 5% by weight of calcined kaolin baked at 900 ° C. was blended with respect to the mixed powder. After that, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was added to the powder in an amount of 30% by weight, adjusted for moisture, press-molded at 50 kgf / cm ² , and steam cured at 60 ° C. for 24 hours. And then dried at 105 ° C. for 24 hours.
Example 6
With respect to the mixed powder of (OF ash: PF ash = 7: 3) and sepiolite (sepiolite content 50% by weight), 5% by weight of calcined kaolin baked at 900 ° C. was blended with respect to the mixed powder.
After that, a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) was added to the powder in an amount of 30% by weight, adjusted for moisture, press-molded at 50 kgf / cm ² , and steam cured at 60 ° C. for 24 hours. And then dried at 105 ° C. for 24 hours.

[Comparative Example]
<Comparative example 1>
30% by weight of a sodium silicate solution (No. 1 sodium silicate: water = 1: 1) is mixed in a mixed powder of OF ash: PF ash = 9: 1 with respect to the powder, and after adjusting the moisture, 50 kgf / cm ² After press molding at 60 ° C. for 24 hours and steam curing, it was dried at 105 ° C. for 24 hours.
<Comparative example 2>
A mixed silicate powder of OF ash: PF ash = 7: 3 is mixed with 30% by weight of sodium silicate solution (No. 1 sodium silicate: water = 1: 1) with respect to the powder, and after adjusting the moisture, 50 kgf / cm ² After press molding at 60 ° C. for 24 hours and steam curing, it was dried at 105 ° C. for 24 hours.
<Comparative Example 3>
A mixed powder of OF ash: PF ash = 5: 5 was mixed with 30% by weight of sodium silicate solution (No. 1 sodium silicate: water = 1: 1) with respect to the powder, and after adjusting the water content, 50 kgf / cm ² After press molding at 60 ° C. for 24 hours and steam curing, it was dried at 105 ° C. for 24 hours.
<Comparative example 4>
A sodium silicate solution (No. 1 sodium silicate: water = 1: 1) is powdered with respect to the mixed powder of OF ash: PF ash = 9: 1 and sepiolite (sepiolite content 30% by weight). After blending 30% by weight and adjusting the moisture, it was press-molded at 50 kgf / cm ² , steam-cured at 60 ° C. for 24 hours, and then dried at 105 ° C. for 24 hours.
<Comparative Example 5>
Sodium silicate solution (No. 1 sodium silicate: water = 1: 1) is powdered to the mixed powder of OF ash: PF ash = 7: 3 and sepiolite (sepiolite content 30 wt%) After blending 30% by weight and adjusting the moisture, it was press-molded at 50 kgf / cm ² , steam-cured at 60 ° C. for 24 hours, and then dried at 105 ° C. for 24 hours.

〔Evaluation methods〕
The pore size distribution of the cured product was measured with a porosimeter. Moreover, the shrinkage rate and the bending strength test were done. The absorption / release test was molded to a size of 100 mm x 100 mm, sealed except the surface to be measured, dried at 105 ° C for 24 hours, and then the humidity was 90% RH (relative humidity) and 40% RH for 24 hours each. Absorbed mass after standing was determined. (Moisture absorption = weight after 24 hours-absolute dry weight)
In order to observe the microstructure of the cured body, the fracture surface was observed with an electron microscope.

〔result〕
The pore distribution measurement result by the porosimeter of the cured geopolymer obtained in Example 1 and Comparative Example 1 is shown in FIG. FIG. 7b shows a pore size distribution diagram and frequency (percentage) in the particle size range.
It is confirmed that the pores are changed from about nm to several tens of nm and from μm to several tens of μm due to the blending of the calcined kaolin. This indicates that pores having a size of around nm to several tens of nm can be easily prepared with a small amount of calcined kaolin, and has properties that are not found in conventional geopolymers.
FIG. 8 a shows the pore distribution measurement results of the cured geopolymer obtained in Example 3 and Comparative Example 3 using a porosimeter.
FIG. 8b shows a pore size distribution diagram and frequency (percentage) in the particle size range.
This is an example in which the pore volume is increased by mixing calcined kaolin with an increase in both the pores of around nm to several tens of nm and μm to several tens of μm, and shows that a porous body can be produced. And have properties not found in conventional geopolymers.
Thus, the pore distribution can be freely controlled by mixing the raw materials and the calcined kaolin.
FIG. 9 shows the results of pore distribution measurement by a porosimeter of the geopolymer cured product obtained in Example 4 and Example 5. By adding sepiolite, an increase in the cumulative pore volume and an increase from around nm to several tens of nm were confirmed. It is considered that pores are also present continuously.

  Table 1 shows the shrinkage, bulk density and bending strength of the cured product.

In PF ash 10 weight% and 30 weight%, there was little shrinkage | contraction rate and the shrinkage | contraction was hardly recognized by the hardening body which mix | blended sepiolite. This is due to the presence of gypsum in the PF ash and the formation of ultrafine quasi-crystals or crystals such as ettringite and zeolite minerals (hydroxysodalite, cancrinite). It is considered that the contraction rate of the body is close to 0, resulting in no contraction.
It is considered that an unprecedented reaction occurs in elution of aluminum from calcined kaolin and generation of amorphous silica after elution. These eliminate the shrinkage rate of the cured body and do not shrink, thus affecting the pore distribution of the cured body. The resulting ultrafine quasicrystals or crystals such as ettringite and zeolite minerals (hydroxysodalite, cancrinite) are themselves nano-sized and have a moisture conditioning function and adsorption function in the interstices between the particles. The material has a pore structure and a continuous pore distribution.
It has been found that a geopolymer material is a material that shrinks originally, but a cured product having almost no shrinkage can be obtained by steam curing after press molding according to the present invention.

  The bulk density of the cured product shows a value of 1.3 to 1.4 in the absence of sepiolite when calcined with kaolin. It can be seen that the weight is reduced to 1.08 by the combination of sepiolite. In the case of kaolin blending, the value is slightly higher than that in the case of calcined kaolin blending. With the cured product obtained by the present invention, a lightweight cured product can be produced, and high strength can be maintained.

The bending strength of the cured product showed a large value of 57 Mpa at 10% by weight of PF ash in the system without sepiolite. In the present invention, it was confirmed that sufficient strength was obtained even when a large amount of sepiolite was blended, and that a high-strength humidity control material could be produced as compared with conventional curing techniques.
Since the conventional geopolymer method requires a long time for the curing reaction, in addition to shrinkage, when a humidity control material is blended, the cured body is particularly warped or deformed during curing, particularly when the surface is severely dried.
In the present invention, the elution of the aluminum in the calcined kaolin is very responsive to the temperature, and since the amount of elution is large relative to the blending amount, the reaction can be carried out in a short time, so a large amount of aluminum ions Is eluted, reacts with the alkali silicate solution, and the reaction can be completed in a short time. By allowing the reaction to be performed in a short time under the curing conditions, a homogeneous material can be obtained. It is considered that fine crystals such as ettringite have a great influence on increasing the strength. Moreover, in this invention, a homogeneous molded object can be obtained by curing a molded object at high temperature.

  Table 2 shows the humidity control performance of the cured body.

  As shown in FIGS. 6a and 6b, it can be seen that the cured body in which the pores are shifted to the nanometer size is very excellent in humidity control performance. Moreover, the humidity control performance was further improved by blending sepiolite. Even if sepiolite is blended, it is considered that the humidity control performance of the cured product of the present invention increases dramatically due to an increase in cumulative pore volume and an increase in the vicinity of nm to several tens of nm as shown in FIG.

  FIG. 10 shows an electron microscope observation of the cured product produced in Example 4. A fine structure of nanometer order is observed, and at the same time, fine crystals such as ettringite in the interstices between particles are confirmed. From this fact, it is considered that the strength can be maintained even if a large amount of piolite is contained.

It is an X-ray-diffraction result of the calcined product of kaolin. It is a differential thermal analysis of kaolin. It is a schematic diagram of the crystal | crystallization of a calcined kaolin. It is an elution characteristic of the calcined product of kaolin. A MAS-NMR ⁽²⁷ Al) spectrum of kaolin calcine. It is an image figure of pore diameter control by baking kaolin additive-free. It is an image figure of pore diameter control by baking kaolin addition. 2 is a pore size distribution curve of a cured geopolymer. It is pore diameter distribution of a geopolymer hardened | cured material. 2 is a pore size distribution curve of a cured geopolymer. It is pore diameter distribution of a geopolymer hardened | cured material. It is a pore diameter distribution curve of the geopolymer hardened | cured material which mix | blended sepiolite. It is a SEM photograph of the fracture surface of a geopolymer hardening body.

Claims (4)

Geo which is obtained by curing, by mixing, molding and curing at high temperature, a filler blended with calcined kaolin and gypsum heat-treated at 850 ° C. to 950 ° C. as an active filler. Polymer high-strength cured body. The geopolymer high-strength cured body according to claim 1, wherein PF ash is used as a component of gypsum. A method for producing a geopolymer high-strength cured product, characterized by mixing a filler in which calcined kaolin and gypsum are blended as an active filler, a geopolymer and water, molding and curing at a high temperature. The method for producing a geopolymer high-strength cured product according to claim 3, wherein PF ash is used as a component of gypsum.