JP7449701B2 - Geopolymer-like cured body - Google Patents

Description

The present invention relates to a new geopolymer-like cured body and a method for producing the same.

Geopolymers are obtained by reacting active fillers containing silicic acid (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ), such as coal ash and blast furnace slag, with an alkaline solution using sodium silicate, sodium hydroxide, etc. It is an amorphous condensate with characteristics such as quick strength development, ability to fix heavy metals, and high fire resistance and sulfate resistance. Because of these characteristics, geopolymers are increasingly expected to be used as cement-free concrete.

On the other hand, research is also being conducted to reduce the weight of geopolymers and use them as heat insulating materials, and a technology has been reported to produce porous geopolymers by adding a foaming agent during the production of geopolymers (Patent Document 1). .

JP 2016-135723 Publication Japanese Patent Application Publication No. 6-183813 Japanese Patent Application Publication No. 6-257041 Special table 2018-527220 publication

However, geopolymers often suffer from surface cracks due to drying shrinkage during curing. Research is underway to incorporate carbon fibers, polyvinyl alcohol fibers, etc. in order to suppress this cracking, but there are problems in that the combination of organic fibers reduces fire resistance and increases costs. .
Therefore, an object of the present invention is to provide a new geopolymer-like cured product that is lightweight and can be used for heat insulating materials, fire-resistant coatings, cold-resistant coatings, fire-resistant adhesives, gap filling materials, etc., and a method for producing the same. It is in.

Therefore, the present inventor focused on rock wool, which is an artificial mineral fiber and has established safety, and by employing rock wool and/or crushed rock wool as the main active filler and reacting it with an alkaline stimulant, The present invention was completed based on the discovery that a geopolymer-like cured product with no drying shrinkage, no cracking due to heating or cooling, low bulk density, and good compressive strength can be easily obtained.

That is, the present invention provides the following inventions [1] to [10].
[1] Geopolymer-like cured product containing rock wool and/or crushed rock wool as an active filler.
[2] The geopolymer-like cured product according to [1], wherein the main component is a reaction product of (A) rock wool and/or ground rock wool and (B) an alkali stimulant.
[3] The geopolymer-like cured product according to [1] or [2], wherein the alkali stimulant is a component selected from alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates.
[4] The geothermal according to [2] or [3], wherein the mass ratio (A/B) of (A) rock wool and/or crushed rock wool and (B) the alkaline stimulant is 1.0 to 20.0. Polymer-like hardened body.
[5] The geopolymer-like cured product according to any one of [1] to [4], further containing an admixture.
[6] The admixture is one or more selected from lightweight aggregates, inorganic fibers other than rock wool, thermal expansion materials, foaming agents, fluidizing agents, endothermic materials, and thickeners [5] The geopolymer-like cured product described above.
[7] The geopolymer-like cured product according to any one of [1] to [6], which has a bulk density of 0.70 to 1.70 g/cm ³ .
[8] The geopolymer-like cured product according to any one of [1] to [7], which has a compressive strength of 0.50 N/mm ² or more.
[9] A method for producing a geopolymer-like cured product, which comprises mixing rock wool and/or pulverized rock wool with an alkaline stimulant and then curing the mixture.
[10] A heat insulating material comprising the geopolymer-like cured product according to any one of [1] to [8].

The geopolymer-like cured product of the present invention has a low bulk density, good compressive strength, and does not cause cracking due to drying shrinkage, heating, or cooling, so it is useful as a heat insulating material, a fire-resistant coating material, and a cold-resistant coating material. . In addition, the bulk density and compressive strength can be adjusted by molding, spray molding, and other forming methods, making it useful as a wide variety of insulation materials, fire-resistant coatings, cold-resistant coatings, fire-resistant adhesives, gap fillers, etc. It is. Furthermore, since rock wool has established safety and is inexpensive, the geopolymer-like cured product of the present invention is also safe and can be produced at low cost.

3 is a photograph of a molded article of Example 3. 2 is a photograph of molded bodies of Example 1 and Example 2. 2 is a photograph of the surfaces of a molded body of Comparative Example 2 and a molded body of Example 2.

The geopolymer-like cured product of the present invention uses rock wool and/or crushed rock wool as an active filler.
The active filler is the main raw material component of the geopolymer, and usually raw materials containing silicic acid (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ), such as coal ash and blast furnace slag, are used. In the present invention, rock wool and/or pulverized rock wool is used as an active filler instead of these coal ash and blast furnace slag.

Rock wool is an artificial mineral fiber produced by mixing basalt, steel slag, etc. with lime, etc. and melting the mixture at high temperatures, and its main components are silicic acid (SiO ₂ ) and calcium oxide (CaO). Rock wool is fibrous and has excellent fire resistance, so it is used as insulation materials, fireproof coatings, culture media, sound absorbing materials, etc.

In addition, molded bodies using rock wool include hot press molded bodies by adding shot, wood chips, and alkaline stimulants generated during the production of rock wool products (Patent Document 2), and molded bodies made of inorganic fibers mixed with an acidic aqueous solution. After adhesion treatment, the molded product is compressed and dehydrated and dried, and the eluted components of the inorganic fibers are collected at the intersections of the inorganic fibers and cured (Patent Document 3), a molded product made of fibers such as rock wool, airgel, filler, and inorganic binder. Composite materials (Patent Document 4) have been reported, but since they use wood chips instead of geopolymers made of rock wool and an alkaline stimulant, they have inferior fire resistance. There were problems such as high bulk density and insufficient insulation performance.

Rock wool usually has a single fiber diameter of 3 μm to 10 μm and an average fiber length of 100 μm to 15,000 μm. The quality of rock wool is controlled by the Rock Wool Industry Association.
Pulverized rock wool is physically crushed rock wool, and has a single fiber diameter of 3 μm to 10 μm, similar to rock wool, and an average fiber length of 20 μm to 1000 μm.

The main component of the geopolymer-like cured product of the present invention is a reaction product of (A) rock wool and/or ground rock wool, which is an active filler, and (B) an alkaline stimulant. That is, it is thought that, like the geopolymer, rock wool and/or ground rock wool as an active filler reacts with the alkaline stimulant to form a geopolymer-like structure.
Examples of rock wool include those whose main raw materials are basalt, steel slag, etc., but those whose main raw materials are steel slag are more preferable.
Alkali stimulants include components selected from alkali metal hydroxides, alkali metal carbonates, and alkali metal silicates. Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide, and more preferably sodium hydroxide. Examples of the alkali metal carbonate include sodium carbonate, sodium hydrogencarbonate, potassium carbonate, and the like, with sodium carbonate being more preferred. Examples of the alkali metal silicate include sodium silicate, potassium silicate, lithium silicate, etc., but sodium silicate is more preferable, and it is even more preferable to use it as water glass.
Although these alkaline stimulants can be used alone, they can also be used in combination after considering the alkali concentration and ingredients.

The mass ratio (A/B) of (A) rock wool and/or crushed rock wool and (B) alkali stimulant in the geopolymer-like cured product of the present invention varies depending on the balance of bulk density and compressive strength of the cured product. Although it can be changed, it is preferably 1.0 to 20.0, more preferably 1.2 to 15.0, even more preferably 1.5 to 13.0, and even more preferably 1.6 to 7.0. Even more preferred.

In addition, the geopolymer-like cured product of the present invention may contain various admixtures in consideration of its applicability as a heat insulating material, fire-resistant coating material, cold-resistant coating material, fire-resistant adhesive, gap filling material, etc. can.
Examples of such admixtures include lightweight aggregates, inorganic fibers other than rock wool, thermal expansion materials based on expanded graphite or vermiculite, foaming agents, fluidizing agents, heat absorbing materials, thickeners, etc. .

Examples of the lightweight aggregate include perlite, slaglite, volcanic rubble, and styrene foam, but perlite is more preferred.
The content of lightweight aggregate in the geopolymer-like cured product of the present invention is determined by drying shrinkage, prevention of cracking by heating and cooling, maintenance of compressive strength, maintenance of fire resistance during high temperature heating, strength and shape retention during heating and cooling. From the viewpoint of maintaining properties, it is preferably 0 to 30 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 5 to 10 parts by mass based on 100 parts by mass of rock wool and/or crushed rock wool. .

Inorganic fibers other than rock wool are preferably inorganic fibers that do not show reactivity with alkaline stimulants, such as glass fibers, metal fibers, carbon fibers, ceramic fibers, and the like. The content of these inorganic fibers in the geopolymer-like cured product of the present invention is 0 parts by mass per 100 parts by mass of rock wool and/or pulverized rock wool from the viewpoint of strength retention and shape retention at high and low temperatures. The amount is preferably 200 parts by weight, more preferably 2 parts by weight to 100 parts by weight, and even more preferably 5 parts to 10 parts by weight.

The geopolymer-like cured product of the present invention can be produced, for example, by reacting rock wool and/or ground rock wool with an alkali stimulant and then curing the product.
Specifically, it can be produced by reacting rock wool and/or pulverized rock wool with an alkaline stimulant solution and then curing. Note that the alkaline stimulant solution can be used by being mixed with other raw materials in advance, but it can also be used by filling the other raw materials and then impregnating the alkaline stimulant solution. Further, the admixture can be used by being added to rock wool and/or crushed rock wool.
A more specific manufacturing method is to fill a mold with rock wool and/or pulverized rock wool and an alkali stimulant solution, and then cure it; A method in which rock wool and/or crushed rock wool and an alkaline irritant solution are mixed just before the application area, and the mixture is sprayed on the application area and then cured (spraying). It can be manufactured by methods such as In addition to the spraying method, it can also be produced by a method in which it is applied to the application area and then cured (spraying method), or a method in which it is filled into gaps and the like and then cured (filling method). Curing can be performed using the same curing methods as for general cement products, such as natural curing or heating curing.

The geopolymer-like cured product of the present invention obtained as described above does not suffer from cracking due to drying shrinkage, heating, or cooling, has a lower bulk density than ordinary geopolymers, and has an appropriate compressive strength. , has low thermal conductivity and is particularly useful as a heat insulating material, fireproof coating material, and cold-resistant coating material.
The bulk density of the geopolymer-like cured product of the present invention is preferably 0.70 to 1.70 g/cm ³ , more preferably 0.70 to 1.60 g/cm ³ from the viewpoint of heat insulation, light weight, and fire resistance. It is preferably from 0.70 to 1.50 g/cm ³ , more preferably from 0.70 to 1.30 g/cm ³ .
In addition, the compressive strength of the geopolymer-like cured product of the present invention is determined by the strength when used as a heat insulating material, fire-resistant coating material, cold-resistant coating material, filler, repair material, etc., and shape retention during heating and cooling. Therefore, 0.50 N/mm ² or more is preferable, and 0.70 N/mm ² or more is more preferable. Moreover, the upper limit of the compressive strength can be manufactured to 16 N/mm ² or less.

The geopolymer-like cured product of the present invention can be manufactured using a mold as described above, or can also be manufactured by a spraying method. Therefore, it is possible to manufacture the molded body in advance and install it at the application site, but it is also possible to form it at the application site by a spraying method, painting method, filling method, etc.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

A geopolymer-like cured body was manufactured using the materials listed in Tables 1 and 2 and according to the following molding method.

Example 1
A NaOH solution with a concentration of 10 mol/L was prepared by dissolving sodium hydroxide, a first grade reagent, in water. Similarly, No. 2 water glass specified in JIS K 1408 was diluted with water to prepare a water glass solution at a volume ratio of 1 part water glass to 2 parts water. This NaOH solution and water glass solution were stirred and mixed at a mass ratio of 1:3 to obtain an alkaline stimulant. Next, the raw materials were mixed at a ratio of 104 parts by mass of an alkaline stimulant to 100 parts by mass of commercially available pulverized rock wool, and the mixture was uniformly mixed in a pan mixer to form a paste, which was then filled into a mold and formed. The surface was smoothed with a trowel. The opening of the formwork was covered with a sheet to prevent drying, protect the surface, and maintain smoothness, and the mold was cured at room temperature for one week. After curing, the mold was demolded and dried for 24 hours in a drying oven with an atmosphere of 60°C to obtain a geopolymer-like cured product.

Example 2
Using the crushed rock wool and alkaline stimulant described in Example 1, after filling the mold with the crushed rock wool, the alkaline stimulant was dropped into the mold and the rock wool and the alkaline stimulant were blended with a rod-shaped tool. Impregnated uniformly. As the alkali stimulant, 88 parts by mass of the alkali stimulant was used based on 100 parts by mass of ground rock wool. The curing and drying conditions after molding were the same as in Example 1 to obtain a geopolymer-like cured product.

Example 3
A geopolymer-like cured product was obtained in the same manner as in Example 1 using 283 parts by mass of an alkali stimulant for 100 parts by mass of rock wool granular cotton.

Example 4
A geopolymer-like cured product was obtained in the same manner as in Example 2 using 295 parts by mass of an alkali stimulant for 100 parts by mass of rock wool granular cotton.

Example 5
Using a raw material containing 245 parts by mass of an alkali stimulant to a total of 100 parts by mass of 50 parts by mass of rock wool granular cotton and 50 parts by mass of commercially available crushed rock wool, a geopolymer was prepared in the same manner as in Example 1. A similar cured product was obtained.

Example 6
Geopolymer-like curing was performed in the same manner as in Example 2 using raw materials containing 245 parts by mass of an alkali stimulant to a total of 100 parts by mass of 50 parts by mass of rock wool granular cotton and 50 parts by mass of commercially available crushed rock wool. I got a body.

Example 7
Rock wool granular cotton was pulverized with a mill to produce pulverized rock wool having an average aspect ratio of 7. A geopolymer-like cured product was obtained in the same manner as in Example 1 using raw materials containing 69 parts by mass of an alkali stimulant based on 100 parts by mass of this pulverized rock wool.

Example 8
A geopolymer-like cured body was obtained using the same raw materials as in Example 7 and in the same manner as in Example 2.

Example 9
100 parts by mass of commercially available crushed rock wool and 10 parts by mass of perlite were mixed in a pan mixer, and then 102 parts by mass of an alkaline stimulant were added and mixed to form a paste. A geopolymer-like cured body was obtained using this paste in the same manner as in Example 1.

Example 10
As in Example 9, 100 parts by mass of commercially available crushed rock wool and 10 parts by mass of perlite were mixed, and as in Example 2, 102 parts by mass of an alkali stimulant was impregnated to obtain a geopolymer-like cured product.

Comparative example 1
80 parts by mass of coal ash and 20 parts by mass of pulverized blast furnace slag were mixed in a pan mixer, and 38 parts by mass of an alkali stimulant was added to a total of 100 parts by mass of coal ash and pulverized blast furnace slag as in Example 1. It was further mixed to form a paste. A molded article was obtained using this paste in the same manner as in Example 1.

Comparative example 2
A molded body was obtained in the same manner as in Example 1 using raw materials containing 54 parts by mass of an alkali stimulant based on 100 parts by mass of pulverized blast furnace slag powder.

Comparative example 3
A molded body was obtained in the same manner as in Example 1 using raw materials in which 38 parts by mass of the alkali stimulant was added to a total of 100 parts by mass of 70 parts by mass of coal ash and 30 parts by mass of pulverized blast furnace slag powder.

Comparative example 4
A molded body was obtained in the same manner as in Example 1 using raw materials in which 38 parts by mass of the alkali stimulant was added to a total of 100 parts by mass of 90 parts by mass of coal ash and 10 parts by mass of pulverized blast furnace slag powder.

A photograph of the molded article of Example 3 is shown in FIG. Photographs of the molded bodies of Example 1 and Example 2 are shown in FIG. Photographs of the surfaces of the molded product of Comparative Example 2 and the molded product of Example 2 are shown in FIG.

The physical properties of the obtained geopolymer-like cured product were measured, and the surface was observed and the heat resistance was evaluated.
The results are shown in Tables 1 and 2.

[Measurement of bulk density]
After drying at 60° C. for 24 hours, the external dimensions were measured with calipers to determine the volume, the mass was also measured, and the bulk density was determined using the following formula.
Bulk density (g/cm ³ ) = mass (g) / volume (cm ³ )

[Measurement of compressive strength]
The maximum load was measured using a strength testing machine, and the maximum load was divided by the cross-sectional area of the center of the specimen to determine the compressive strength (N/mm ² ). The test conditions were as follows: A test specimen measuring 40 mm in width x 40 mm in length x 80 mm in height was pressurized from above at a speed of 2 mm/min.

[Surface observation]
The surface was visually observed before and after curing to check for cracks caused by drying shrinkage. The observation criteria were as follows: No cracks at all were marked as ○, and cracks were marked as ×.

[Measurement of thermal conductivity]
Thermal conductivity was measured using a thermal conductivity meter based on the heat flow meter method described in JIS A 1412-2. The measurement temperature was set at a center temperature of 20°C and a temperature difference of 20°C.
The thermal conductivity of the geopolymer-like cured body of Example 2 was 0.216 W/mK.

[Check heat resistance]
After heating at 400° C. for 3 hours in an electric furnace, cracks on the surface were observed. The observation criteria were as follows: Comparing to before heating, a sample with no cracks was rated as ○, and a sample with cracks was graded as ×.

[Cold resistance confirmation]
After being immersed in liquid nitrogen for 1 minute, it was taken out and cracks on the surface were observed. The criteria for surface observation were as follows: Comparing with before immersion, a sample with no cracks was graded as ○, and a sample with cracks was graded as x.

As shown in Tables 1 and 2, the geopolymer-like cured product according to the present invention was a cured product with excellent heat resistance and cold resistance without drying shrinkage, heating, or cooling-induced cracking. Furthermore, the geopolymer-like cured product of the present invention has a bulk density of 0.70 to 1.70 g/cm ³ , is lightweight, has low thermal conductivity, and is excellent as a heat insulating material. Do you get it. It was also found that it had a compressive strength of 0.50 N/mm ² or more and had good workability.
On the other hand, conventional geopolymers tend to crack due to drying shrinkage and have low heat resistance.

Claims (6)

A geopolymer-like cured product containing rock wool and/or ground rock wool as an active filler, the main component being the mass ratio (A/ B) is a reactant with 1.6 to 7.0,
The bulk density is 0.70 to 1.70, the compressive strength is 0.50 to 16.0 N/mm ² ,
the alkali stimulant is an alkali metal hydroxide and an alkali metal silicate ;
A geopolymer-like cured product that does not contain wood-based reinforcing materials. The geopolymer-like cured product according to claim 1, further comprising an admixture. 3. The geothermal composition according to claim 2, wherein the admixture is one or more selected from lightweight aggregates, inorganic fibers other than rock wool, thermal expansion materials, fluidizing agents, endothermic materials, foaming agents, and thickeners. Polymer-like hardened body. The geopolymer-like cured product according to any one of claims 1 to 3, which has a bulk density of 0.70 to 1.30 g/cm ³ . The method for producing a geopolymer-like cured product according to any one of claims 1 to 4, characterized in that rock wool and/or crushed rock wool and the alkaline stimulant are mixed and then cured. A heat insulating material comprising the geopolymer-like cured product according to any one of claims 1 to 4.