JP2001019571A - Production of autoclaved lightweight concrete and autoclaved lightweight concrete panel obtained by the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing by which an autoclaved lightweight concrete(ALC) scarcely causing cracking, etc., especially in an ALC panel and excellent in dimensional stability and bending strength, etc., is obtained while using the largest possible amount of a readily available and inexpensive siliceous raw material in a method for producing the ALC and to produce the ALC panel obtained by the method. SOLUTION: A mixed siliceous stone prepared by mixing a siliceous stone having <10 μm average quartz crystal grain diameter with a siliceous stone having 10-500 μm average quartz crystal grain diameter and regulating the average quartz crystal grain diameter of the mixed siliceous stone to 15-300 μm and the mixing ratio of the siliceous stone having <10 μm average quartz crystal grain diameter to <=60 wt.% is used as a siliceous stone in a siliceous raw material in a method for producing an ALC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing lightweight cellular concrete and a lightweight cellular concrete panel obtained by the method. More specifically, it is possible to use an inexpensive siliceous raw material that can be easily obtained without deteriorating the quality by using a mixed silica stone having an average quartz crystal grain diameter of at least two levels or more as the siliceous raw material silica used. The present invention relates to a method for producing lightweight cellular concrete and a lightweight cellular concrete panel obtained thereby.

[0002]

2. Description of the Related Art Light-weight cellular concrete (hereinafter referred to as ALC) is generally made of a silicate material such as silica stone and a calcareous material such as quicklime and cement as a main material, and further added with gypsum, a foaming agent and water and mixed. The slurry is poured into a mold, foamed, semi-cured, and then autoclaved for production. In producing this ALC, the quality of the siliceous raw material is an important factor for the quality stability and improvement. In particular, the crystal grain size affects the drying shrinkage and compressive strength that cause cracking of the ALC panel. It is known that the siliceous raw material generally has a high SiO ₂ content and preferably has a crystal grain size of silica in a range of about 10 μm to 100 μm.

[0003] However, the production source of siliceous raw materials having a crystal grain size of silica within the above range is locally limited, and reserves are decreasing, so that it becomes gradually difficult to obtain.
It is also a factor in increasing the cost of LCs and their panels. In recent years, various countermeasures have been proposed, and as a method of using silica having a quartz crystal grain size of less than 10 μm as a siliceous raw material for ALC, and using a high strength cement as a part of the calcareous raw material ( JP-A-8-2593
No. 47) and a method using silica stone having a quartz crystal particle diameter of less than 10 μm and crushed stone powder such as igneous rock and sedimentary rock (Japanese Patent Laid-Open No.
No. 259348) has been proposed and disclosed.

[0004]

However, the quality of ALC obtained by any of the above production methods is not always satisfactory, and the crystal grain size of silica is about 10 μm or less.
AL manufactured using only 100 μm silica as a siliceous raw material
Compared with C, especially the surface of the drying shrinkage which affects the crack generation of the panel is still insufficient, and the panel has excellent long-term physical properties such as dimensional stability and bending strength without crack generation for a long time. In order to obtain ALC, other measures were required. In addition, the production method of Japanese Patent Application Laid-Open No. Hei 8-259347 requires expensive early-strength cement, and thus has another problem in terms of cost reduction, which is another problem.

Accordingly, an object of the present invention is to provide an ALC production method in which gypsum and a foaming agent are added to a main raw material composed of a siliceous raw material and a calcareous raw material to form a slurry, which is formed and autoclaved, and which is easy to obtain and inexpensive. ALC with excellent long-term physical properties such as dimensional stability and flexural strength, especially in the absence of cracks in the ALC panel, is required while using as much siliceous raw material as possible. Method for producing ALC that can be produced using ordinary cement and A obtained by the method
An object of the present invention is to provide an LC panel.

[0006]

In order to solve the above-mentioned problems, the present invention provides a slurry obtained by adding water, gypsum and a foaming agent to a main raw material composed of a siliceous raw material mainly composed of silica and a calcareous raw material. Then, after injecting it into a mold, the molded semi-cured product is subjected to autoclave curing in an ALC production method, wherein the quartz in the siliceous raw material has a quartz crystal particle size of 1%.
A mixture of silica having a particle size of less than 0 μm and silica having a particle size of 10 μm to 500 μm has an average quartz crystal grain size of 15 μm to 30 μm.
An ALC manufacturing method is adopted, wherein a mixed silica having a mixing ratio of silica of less than 10 μm and 60 wt% or less is used.

Another aspect of the present invention is characterized in that the dry shrinkage is 0.03% or less, and 5 to 50% by weight of unreacted silica in all the components has an average quartz crystal grain size of less than 10 μm. ALC panel.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Among the reactions in the ALC manufacturing process,
The most important reaction for producing an ALC having practical dimensional stability and long-term physical properties is a reaction that generates tobermorite by a reaction between calcium and silica in a foam-hardened slurry during autoclave curing.

At this time, in order to obtain an ALC panel having a small drying shrinkage and a small number of cracks, it is necessary to form tobermorite having a high degree of crystallinity. Must be used.

Conversely, silica having a small average quartz crystal grain size is
In the reaction during autoclave curing, it is easily eluted in the early stage of curing to form low calcium CSH,
Since H delays the crystal growth of tobermorite from the middle stage of curing, the reactivity of tobermorite deteriorates and the drying shrinkage increases.

Therefore, in the present invention, as the silica in the siliceous raw material, silica having a small average quartz crystal grain size and silica having a large average quartz crystal grain size are mixed to make the average quartz crystal grain size within a specific range. The object of the present invention has been solved by using the mixed silica stone formed.

That is, silica having an average quartz crystal grain diameter of less than 10 μm and silica having an average quartz crystal grain diameter of 15 μm to 300 μm, more preferably 25 μm to 200 μm, are used by mixing with silica having an average quartz crystal grain diameter of 10 μm to 500 μm. In this case, by limiting the silica having an average quartz crystal grain size of less than 10 μm to 60% by weight or less in the mixed silica, the reactivity of tobermorite formation is improved by combining these two factors, As a result, it is possible to obtain an ALC panel having a small drying shrinkage ratio, a small crack generation of the obtained ALC panel, and a high bending strength while using inexpensive silica stone which is easily available.

In other words, if the average quartz crystal grain size of the mixed silica is less than 15 μm, the resulting ALC does not have a reduced drying shrinkage, and cracks are likely to occur in the panel. Further, when the average quartz crystal grain size exceeds 300 μm, the compressive strength of the obtained ALC decreases, and only a small amount of silica having an average quartz crystal grain size of less than 10 μm can be used. This is a problem in the effective use of natural silica.

Further, when the silica having an average quartz crystal grain diameter of less than 10 μm exceeds 60% by weight in the mixed silica, the drying shrinkage is also increased, so that it is impossible to obtain an ALC having a desired quality and a panel thereof. However, in order to solve the problem of cost reduction by effective use of silica having an average quartz crystal grain size of less than 10 μm, at least 10% by weight is required.
It is desirable to make the above.

In the present invention, the mixed silica is used in an amount of 70 to 100% by weight of the siliceous raw material, and silica having a SiO ₂ content of 85% by weight or more in each silica before mixing is used. In addition, gypsum is 2% based on the solid content of the slurry.
When the content is added to ８8% by weight, the crystallinity of tobermorite is further increased, the drying shrinkage of the obtained ALC is further reduced, and the effect of the present invention is remarkable. As gypsum, anhydrous gypsum and gypsum are usually used. Further, other materials may be added to add other characteristics.

In the present invention, two or more kinds of silica having different average quartz crystal grain diameters may be used, and their production areas may be different. Silica sand can also be used. In addition, as the siliceous material, diatomaceous earth, fly ash,
It is also possible to partially mix amorphous silica such as blast furnace slag.

The method for measuring the average quartz crystal grain size of silica in the production method of the present invention is as follows.
Take a picture with a polarizing microscope of 0 to 400 times and
The cross-sectional diameter at each of the locations is measured, and the average value is calculated to be the average quartz single crystal grain size. The average quartz grain size of mixed silica is
It is calculated from the crystal grain size of each silica stone and its usage ratio. The SiO ₂ content of the silica is measured by X-ray fluorescence.

As the calcareous raw material, slaked lime, quicklime and various cements can be used. This cement is
Although the purpose of the present invention can be sufficiently achieved by using ordinary cement, the use of the early-strength cement further reduces the drying shrinkage and improves the quality. In addition, these cements usually contain about 20% by weight of silicic acid, but in the present invention, this silicic acid is not included in the siliceous raw material. As the foaming agent, metal aluminum powder is usually used.

In the ALC panel of the present invention, the dry shrinkage is 0.03% or less, and the unreacted silica in all the components contains 5 to 5 pieces of silica (quartz single crystal) having an average quartz crystal grain size of less than 10 μm.
0% by weight. More preferably, the compression strength is 3.0 N / mm ² or more and the density is 300 to 550 kg / m ³ . Since the drying shrinkage of this ALC panel is quite low at 0.03% or less, cracks are unlikely to occur and the bending strength is high. In addition, this ALC panel is obtained by the manufacturing method of the present invention.

The method for measuring the average quartz crystal grain size of the silica (quartz single crystal) having a size of less than 10 μm among the unreacted silica in the ALC panel of the present invention is to take a photograph taken with a scanning electron microscope at a magnification of 1000 to 5000 times. Then, the transverse diameters at the five locations are measured, and the average value is calculated.

The method for producing ALC of the present invention and AL
The ALC in the C panel is not limited to the range specified in JIS, but means a lightweight lightweight cellular concrete in a broad sense.

[0022]

EXAMPLES Examples of the method for producing ALC of the present invention and comparative examples thereof will be described below in detail. [Example 1] Silica was mixed and crushed so that 20% by weight of silica from Oma, Gunma Prefecture having an average crystal grain size of 3 μm and 80% by weight of silica from Awano, Tochigi Prefecture with an average crystal grain size of 30 μm. did. The average quartz crystal grain size of this mixed silica is about 25.
μm. ALC was manufactured under the blending conditions shown in Table 1 using the obtained mixed silica, quicklime, ordinary Portland cement and gypsum dihydrate as raw materials.

The compressive strength, density, and drying shrinkage of this ALC panel were measured in accordance with JIS A5416.
It was shown to. The tobermorite crystal formation state in this ALC was determined by using powder X-ray diffraction method with tobermorite 5 strong line (Cu
Kα 2θ = 7.8 °, 16.2 °, 29.0 °, 3
0.0 °, 31.8 °), and the total was set to 100.

The X-ray diffraction conditions in this case are shown below. Apparatus: Powder X-ray diffractometer with monochromator Measurement angle: 5 to 45 ° (2θ) Step sampling: 0.02 ° Scan speed: 2 ° / min Measurement points: CPS The above compressive strength, density, and dry shrinkage The method for measuring the state of tobermorite crystal formation is the same in all of the following examples and comparative examples.

According to this example, as shown in Table 2, sufficient compressive strength was obtained, and a considerably low dry shrinkage of 0.018% was obtained. Furthermore, the ALC panel was exposed outdoors against the uncoated substrate, and cracks were observed for 8 weeks after the production. No cracks were found.

Example 2 20% by weight of silica from Oma, Gunma Prefecture having an average quartz crystal grain size of 3 μm, and an average quartz crystal grain size of 3
Silica was mixed and pulverized so that the silica of 0 μm from Awano-cho, Tochigi Prefecture became 80% by weight. The average quartz crystal grain size of the mixed silica is about 25 μm. The resulting mixed silica, quicklime,
An ALC panel was produced using the early strength Portland cement and gypsum dihydrate as raw materials under the blending conditions shown in Table 1.

As shown in Table 2, all of the compressive strength, the peak height of the five strong lines of tobermorite, and the drying shrinkage were further superior to those of Example 1. No cracking occurred for 8 weeks after production.

Example 3 50% by weight of silica from Oma, Gunma Prefecture having an average quartz crystal grain size of 3 μm, and an average quartz crystal grain size of 1
Silica was mixed and pulverized so that the silica of 20 μm from Awano-cho, Tochigi Prefecture became 80% by weight. The average crystal grain size of the mixed silica is about 62 μm. An ALC panel was manufactured using the obtained mixed silica, quicklime, ordinary Portland cement and gypsum as a raw material under the blending conditions shown in Table 1.

As shown in Table 2, also in this example, excellent compressive strength, peak height of Tobermorite 5 strong line, and drying shrinkage were obtained, and no crack was generated for 8 weeks after production.

Example 4 50% by weight of silica from Oma, Gunma prefecture having an average quartz crystal grain size of 3 μm, and an average quartz crystal grain size of 3
Silica was mixed and pulverized so that the silica of 0 μm from Awano-cho, Tochigi Prefecture became 50% by weight. The average crystal grain size of the mixed silica is about 17 μm. ALC was manufactured under the mixing conditions shown in Table 1 using the obtained mixed silica stone, quicklime, ordinary Portland cement and gypsum dihydrate as raw materials.

As shown in Table 2, the compressive strength, the peak height of the five strong lines of tobermorite, and the drying shrinkage were almost the same as those in Example 1. In addition, no crack was generated for 8 weeks after the production.

[Comparative Example 1] ALC was manufactured under the mixing conditions shown in Table 1 using as raw materials silica, quicklime, ordinary Portland cement and gypsum gypsum from Oma, Gunma Prefecture having an average quartz crystal grain size of 3 µm. The compressive strength of this ALC, the peak height of the five strong lines of tobermorite, and the drying shrinkage were measured in the same manner as in Example 1 and shown in Table 2.

As shown in Table 2, the compressive strength was small, the dry shrinkage was as large as 0.04%, and the peak height of the tobermorite 5 strong line was as small as 70 as in Example 1. Further, as a result of observing the occurrence of cracks in the same manner as in Example 1, the occurrence of cracks was observed two weeks after production.

[Comparative Example 2] Silica from Oma, Gunma prefecture having an average quartz crystal grain size of 3 μm was 70% by weight, and the average quartz crystal grain size was 3
Silica was mixed and pulverized so that 0 μm of silica from Awano-cho, Tochigi Prefecture became 30% by weight. The average quartz crystal grain size of the mixed silica is about 11 μm. The resulting mixed silica, quicklime,
ALC was produced from ordinary Portland cement and gypsum dihydrate under the mixing conditions shown in Table 1. As shown in Table 2, this AL
The drying shrinkage of C was as large as 0.037%, and the peak height of the tobermorite 5 strong line was 77, which was smaller than that of Example 1. Five weeks after the production, cracks were observed.

[Comparative Example 3] Silica from Oma, Gunma Prefecture having an average quartz crystal grain size of 3 μm was 70% by weight, and the average quartz crystal grain size was 1
Silica was mixed and pulverized so that 20 μm of silica from Awano-cho, Tochigi Prefecture became 30% by weight. The average quartz crystal grain size of the mixed silica is about 38 μm. ALC was manufactured under the mixing conditions shown in Table 1 using the obtained mixed silica stone, quicklime, ordinary Portland cement and gypsum dihydrate as raw materials. As shown in Table 2, the compressive strength is similar to that of the example, but the dry shrinkage is 0.035.
%, And cracks were observed after 8 weeks of production.

Comparative Example 4 50% by weight of silica from Oma, Gunma Prefecture having an average quartz crystal grain size of 3 μm was crushed powder (SiO ₂
(The content is 75% by weight) and 50% by weight. An ALC was produced from the resulting mixture, quicklime, ordinary Portland cement and gypsum dihydrate under the mixing conditions shown in Table 1.
As shown in Table 2, the compressive strength was smaller than that of the example, the dry shrinkage was as large as 0.035%, and cracks were observed after 8 weeks of production.

[0037]

[Table 1] The SiO ₂ content in the silica component from Oma, Gunma Prefecture used in all the above Examples and Comparative Examples was 94% by weight, and the SiO ₂ content in the silica stone component from Awano Town, Tochigi Prefecture was 92% by weight. Was.

In Table 1, the weight percentages of the Oma-tsuma and Awano-machi silica stones are percentages of the total siliceous raw material (ie, total silica stone), and the weight percentages of silica stone, quicklime, cement and gypsum
Is the ratio in the total solid content. In addition, the cement type usually indicates ordinary Portland cement, and the early strength indicates the early Portland cement.

[0039]

[Table 2] As described above, in each of the examples, no crack was generated even after 8 weeks from the production of the ALC panel as compared with each of the comparative examples.
This shows that the ALC panels of the respective examples can substantially endure long-term use.

[0040]

According to the method for producing ALC of the present invention, silica having a small average quartz crystal grain size which is difficult to use as a siliceous raw material, in particular, silica which is easily available and inexpensive and has a particle size of less than 10 μm, can be dried at a low shrinkage ratio. A considerable amount can be used without deteriorating the quality of ALC. Also, the use of ordinary cement, which does not necessarily require the use of early-strength cement, can provide ALC of sufficient quality. As a result, the ALC and its panel can be manufactured at a low cost, and the crack generation and the like are small, and the quality of the ALC panel is the same as that of a conventionally used ALC panel using 100% of large silica having an average quartz crystal grain size of 10 μm or more. Things are obtained.

Further, since the ALC panel of the present invention has a considerably small dry shrinkage, cracks are unlikely to occur and the bending strength is high.

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Mototaka Niwa 2035 Shimoi, Shioimachi, Owariasahi City, Aichi Prefecture F-term in the Materials and Technological Research Laboratories Co., Ltd. 4G012 MB23 PA04

Claims (5)

[Claims] 1. A slurry obtained by adding water, gypsum and a foaming agent to a main raw material comprising a siliceous raw material mainly composed of silica and a calcareous raw material, forming a slurry, injecting the slurry into a mold, and forming a slurry. A method for producing lightweight cellular concrete in which a cured product is cured by autoclaving, wherein the silica in the siliceous raw material has an average quartz crystal grain size of 1
A mixture of silica having a particle size of less than 0 μm and silica having a particle size of 10 μm to 500 μm has an average quartz crystal grain size of 15 μm to 30 μm.
A method for producing lightweight cellular concrete, characterized in that a mixed silica having a mixing ratio of silica of less than 10 μm and 60 wt% or less is used. 2. The method for producing lightweight cellular concrete according to claim 1, wherein the mixed silica is used in an amount of 70 to 100% by weight of the siliceous raw material. 3. The method for producing lightweight cellular concrete according to claim 1, wherein the SiO ₂ content in the silica stone having an average quartz crystal grain size of less than 10 μm and in the silica stone having an average crystal grain size of 10 μm to 500 μm is 85% by weight or more. 4. The method for producing lightweight cellular concrete according to claim 1, wherein the gypsum is added in an amount of 2 to 8% by weight based on the solid content of the slurry. 5. A lightweight cellular concrete panel characterized in that the dry shrinkage is 0.03% or less, and 5-50% by weight of unreacted silica in all components has an average quartz crystal grain size of less than 10 μm.