JP6933422B2 - How to manufacture lightweight cellular concrete panels - Google Patents

Description

The present invention relates to a method for manufacturing a lightweight cellular concrete panel (ALC panel). More specifically, the present invention relates to an ALC panel used for a wall, a roof, a floor, or the like of a building, and relates to a method for manufacturing an ALC panel capable of reducing the amount of silica stone used.

Lightweight aerated concrete (ALC) contains air bubbles and pores inside, and has an excellent property that it is extremely lightweight with an absolute dryness specific gravity of about 0.5 and has relatively high strength. It is high-temperature and high-pressure steam curing by autoclave that expresses this strength, and in this curing process, tobamolite, a calcium silicate hydrate, is produced from siliceous raw materials such as silica stone and calcareous raw materials such as cement and quicklime. NS.

Tobermorite The formula is _{5CaO · 6SiO 2 · 5H 2 O} , theoretical values of the Ca / Si molar ratio is 5/6 = 0.83. In the industrial production of ALC panels, the siliceous raw material is usually set to be larger than the theoretical value, and the Ca / Si molar ratio is in the range of about 0.3 to 0.7.

Here, in recent years, the supply amount of various raw materials is becoming insufficient at the manufacturing site of ALC panels. Among the above-mentioned natural raw materials for producing ALC, silica stone used as a siliceous raw material is in a tight situation, for example, the supply amount cannot keep up with the demand at some sites.

Mullite is considered to be a promising candidate as an alternative raw material to make up for the lack of silica stone. While mullite is mineral rational formula of _{3Al 2 O} 3 · 2SiO 2, During tobermorite, there usually also the order of about 15% of SiO ₂ is _Al 2 _{O 3} substitution, silica Mullite is considered to be a promising alternative raw material for. For example, Patent Document 1 also discloses that coal ash containing mullite can be used as a siliceous raw material.

However, in the production of ALC panels that are required to have excellent compressive strength, it is extremely important to generate a large amount and homogeneously of tovamorite having high crystallinity, and for that purpose, for example, variations in quartz crystal size. It has been a conventional wisdom that the selection of high-grade siliceous raw materials, such as those made of rough stones with a small amount of water, is essential (see Patent Document 2). In this regard, also in Patent Document 1 described above, when coal ash (containing mullite) is used as a siliceous raw material, the strength and physical properties are lowered as compared with the case where silica stone and silica sand are used, and various problems associated therewith. It is clearly stated that is likely to occur. Further, in the same document, the ratio of mullite that can be substituted is only vaguely disclosed in an extremely wide range of 1.0 to 40.0 wt%. As a matter of fact, no concrete technical means for substituting a part of the siliceous raw material with mullite while maintaining sufficient compressive strength has not been found yet, and the replacement of the siliceous raw material with mullite is an ALC panel. The reality is that practical application has not progressed at the manufacturing site.

International Publication No. 2014/069534 Japanese Unexamined Patent Publication No. 2001-302325

The present invention reduces the amount of silica stone used while maintaining the quality of the ALC panel by substituting a part of the silica stone used as the siliceous raw material with mulite while maintaining the sufficient compressive strength required for the ALC panel. It is an object of the present invention to provide a method for manufacturing an ALC panel that can be used.

In the production of ALC panels, the present inventors limit the amount of substitution in the siliceous raw material within a predetermined ratio range, so that one of the silica stones constituting the siliceous raw material while maintaining sufficient compressive strength. We have found that the part can be replaced by mulite, and have completed the present invention. Specifically, the present invention provides the following.

(1) A manufacturing method for producing a lightweight cellular concrete panel by curing an ALC slurry containing a siliceous raw material mainly composed of silica stone and a calcareous raw material, wherein the silica stone constituting the siliceous raw material is produced. A method for manufacturing a lightweight cellular concrete panel in which a part of the mullite is replaced with a mullite so that the content of the mullite with respect to the total content of silica stone and the mullite in the siliceous raw material is 2.5% by mass or more and 15% by mass or less. ..

According to the invention of (1), in the production of ALC panels, a part of silica stone whose receipt is tight as a siliceous raw material while maintaining the compressive strength of the ALC panel is an industry represented by tile selben and the like. It can be replaced with silica stone, which is also contained in a certain amount of waste.

(2) The method for producing a lightweight cellular concrete panel according to (1), wherein the content of mullite with respect to the total content of silica stone and mullite in the siliceous raw material is 2.5% by mass or more and 10% by mass or less.

According to the invention of (2), the amount of mullite added in the invention of (1) was further limited to a specific preferable range. As a result, the above-mentioned effect of the invention of (1) can be enjoyed in a more preferable manner under normal operating conditions without extending the autoclave curing time.

(3) The content of mullite with respect to the total content of silica stone and mullite in the siliceous raw material is set to more than 10% by mass and 15% by mass or less, and the autoclave curing time is extended to remove a part of silica stone. The method for manufacturing a lightweight aerated concrete panel according to (1), wherein an amount of tobamolite equivalent to that in the case where mullite is not replaced is generated.

According to the invention of (3), on the premise that the amount of mullite added in the invention of (1) is carried out together with the optimization of the operating conditions such as the extension of the autoclave curing time, the substitution ratio of silica stone with mullite is further set. Limited to a relatively high specific range. Thereby, in the invention of (1), silica stone can be replaced with mullite in a larger proportion.

According to the present invention, the amount of silica stone used is maintained while maintaining the quality of the ALC panel by substituting a part of the silica stone used as the siliceous raw material with mulite while maintaining the sufficient compressive strength required for the ALC panel. It is possible to provide a method for manufacturing an ALC panel, which can reduce the amount of ALC panel.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.

<Manufacturing method of ALC panel>
The conventional method for manufacturing a general ALC panel is as follows. In the production of ALC panels, first, an ALC slurry containing a siliceous raw material such as silica stone and a calcareous raw material such as cement and quicklime as main raw materials is prepared. Then, this is cured in the mold to form a semi-plastic body. Next, this semi-plastic body is cut to a predetermined size, and the cut semi-plastic body is charged into an autoclave and steam-cured at a high temperature and high pressure. By going through these processes, an ALC panel having a predetermined shape can be manufactured.

In the production method of the present invention, a part of the siliceous raw material, which is the main raw material of the ALC slurry, is replaced with a specific ratio by using mulite, which is also contained in a certain amount of industrial waste such as tile selben. It is characterized by that.

<ALC slurry>
Generally, in the ALC slurry used for manufacturing an ALC panel, in addition to the above-mentioned siliceous raw material and calcareous raw material which are the main raw materials, a process repeating raw material obtained by crushing ALC waste material, aluminum powder as a foaming agent, a surfactant and the like are added. It can be obtained by adding a product and warm water and kneading. The ALC slurry used in the method for producing an ALC panel of the present invention replaces a part of the siliceous raw material among the main raw materials of the ALC slurry with mullite. Mullite is produced in small amounts of natural products, and synthetic products are widely used. However, it is also contained in a certain amount in industrial waste such as tile selben, and by using this as the raw material. , Can be obtained at a very low price.

As described above, the production of tovamorite in the process of autoclave curing plays an important role in improving the strength of the ALC panel. In order to promote the production of tovamorite, the siliceous raw material is preferably of high quality as described in Patent Document 2, for example. Therefore, for example, if _{this is replaced with mullite, which is inferior in the SiO 2} content, it is considered that the production of tovamolite, which contributes to the improvement of the strength of the ALC panel, becomes insufficient and the strength of the ALC panel is lowered.

Here, tobermorite the formula is _{5CaO · 6SiO 2 · 5H 2 O} . The theoretical value of the Ca / Si molar ratio of this tovamorite is 5/6 = 0.83. The molar ratio of total lime to silicic acid CaO / SiO ₂ in the ALC slurry affects the composition of calcium silicate hydrate, which is a precursor of tovamorite. Theoretically, in order to efficiently produce tovamorite, it is necessary to control this molar ratio within the range of 0.4 or more and 0.8 or less.

However, in the actual manufacturing process of the ALC panel, in order to improve the physical characteristics of the autoclave cured product, the above Ca / Si molar ratio of the ALC slurry is adjusted and set in the direction of Si richer than the above theoretical value. It was mostly done. Specifically, the Ca / Si molar ratio of the ALC slurry is generally adjusted to a range of about 0.3 or more and 0.7 or less. Among these reasons, at least one of the following reasons can be mentioned. That is, the unreacted siliceous raw material that did not contribute to the formation of tovamorite remains in the ALC matrix as it is, and also contributes to the improvement of the strength of the ALC panel by the aggregate effect.

The ALC slurry used in the method for producing an ALC panel of the present invention mainly contains a siliceous raw material and a calcareous raw material mainly made of silica stone. The molar ratio (Ca / Si) of lime and silicic acid in the ALC slurry is 0.3 or more and 0.7 or less. This point is the same as the slurry used for manufacturing the conventional ALC panel.

The ALC slurry used in the method for producing an ALC panel of the present invention replaces at least a part of the silica stones constituting the siliceous raw material with mullite. As the calcareous raw material and other material components constituting the ALC slurry, the same ones as those of the conventional slurry can be used.

[Silicic acid raw material]
As described above, the siliceous raw material used in the ALC slurry of the present invention is a part of silica stone replaced with mullite. Here, mullite and is represented by the chemical formula _{3Al 2 O} 3 · 2SiO 2 having a single chain structure, which is a compound of aluminum oxide and silicon dioxide.

The content ratio of mullite to the total content of silica stone and mullite in the siliceous raw material may be 2.5% by mass or more and 15% by mass or less. As a result, despite the replacement of silica stone with mullite, substantially the same tobamolite is produced, and the ALC panel can maintain sufficient strength. As will be shown later in Examples, the strength of the ALC panel is in the case of a normal composition in which the content ratio of mullite is 0% by mass in the range of 2.5% by mass or more and 15% by mass or less of the above-mentioned content ratio of mullite. It shows a numerical value that is almost inferior to. Therefore, in the implementation of the production method of the present invention, as a guideline when mullite is used, the content ratio is 2.5% by mass or more and 15% by mass or less, that is, the substitution rate of silica stone by mullite is 2.5% by mass. It is preferably 15% by mass or less.

However, the ratio of the content of mullite to the total content of silica stone and mullite in the siliceous raw material is more preferably 2.5% by mass or more and 10% by mass or less. By limiting the ratio of substitution by mullite to this range, as will be shown later in the examples, the strength of the ALC panel can be adjusted to 0% by mass without changing the conditions such as the autoclave curing time. The value can be almost the same as that of the normal composition.

Further, the content ratio of mullite to the total content of silica stone and mullite in the siliceous raw material can be more than 10% by mass and 15% by mass or less. In this case, for example, as shown later in Examples, the strength of the ALC panel is increased by extending the autoclave curing time by about 3 to 6 hours as compared with the conventional one, so that the strength of the ALC panel is increased by a normal composition having the above content ratio of 0% by mass. The value can be almost the same as the case.

[Climestone raw material]
As described above, the calcareous raw material used in the method for producing an ALC panel of the present invention has a molar ratio (Ca / Si) of lime and silicic acid in the ALC slurry of 0.3 or more and 0.7 or less. Various conventionally known cement-based materials can be appropriately used for ALC panel manufacturing. Specific examples include blast furnace cement, silica cement, fly ash cement and the like in addition to Portland cement such as ordinary Portland cement and early-strength Portland cement. It is preferable to use these appropriately depending on the intended use of the ALC panel.

[Other materials]
The compounding ratio with other materials of the ALC slurry is not particularly limited. It may be set appropriately in consideration of the application. It is also possible to add an admixture such as a general AE agent, an AE water reducing agent, and a high-performance AE water reducing agent.

Hereinafter, the method for manufacturing the ALC panel of the present invention will be described in detail with reference to examples. The present invention is not limited to the embodiments shown below.

<Manufacturing of ALC panel>
First, a solid raw material was prepared as follows in order to prepare an ALC slurry used for manufacturing the ALC panel of the reference example. Silica stone sand, quicklime, ordinary Portland cement, gypsum, and repeated raw materials were mixed in the amounts shown in Table 1 below. The unit of the numerical value of each material in Table 1 is g.

Then, with respect to the solid raw materials of the above reference examples, some of the silica stones contained therein were replaced with mullite at the ratios shown in Table 2 (denoted as "Mullite addition amount (%)" in Table 2). Was used as the solid raw material of each Example and Comparative Example. 60 parts by weight of water, a small amount of aluminum powder and a surfactant were added to 100 parts by weight of each of these solid raw materials and kneaded to obtain each ALC slurry of Reference Example, Example and Comparative Example.

Each of the above ALC slurries was subjected to high temperature and high pressure steam curing for 6 hours in an autoclave at 180 ° C. and 10 atm after the bubbles were generated and expanded by the reaction of the aluminum powder and cured by the hydration of the calcareous raw material. , Each ALC panel sample of Example and Comparative Example was obtained.

Further, in the reference example and each of the ALC panels of the examples and the comparative examples, the time required for high-temperature and high-pressure steam curing was extended by 3 hours or 6 hours, and the other examples were manufactured under the same conditions. ALC panel samples prepared under the conditions were obtained.

For each sample thus obtained, the amount of tomovalite produced (relative amount) in each sample was calculated by measuring the height of the main peak (7.8 °) of the tovamolite of XRD (CuKα). This was evaluated based on the following evaluation criteria.
(Evaluation criteria)
A: The amount of tomovalite produced exceeded the reference example.
B: The amount of tomovalite produced was 90% or more and 100% or less of the amount of the reference example.
C: The amount of tomovalite produced was 70% or more and less than 90% of the amount of the reference example.
D: The amount of tomovalite produced was less than 70% of the amount of the reference example.

From Table 2, it can be seen that when the amount of replacement by mullite is within a specific range, sufficient tobamolite is produced even if silica stone, which is a natural resource, is replaced with mullite within a certain ratio. It is considered that the reason why the amount of tovamolite produced is relatively reduced when the amount of substitution by mullite exceeds a certain ratio is that the amount of Al ₂ O _{3 with respect to tova molite exceeds the solid solution limit.} Based on the above, according to the production method of the present invention, the quality of the ALC panel was maintained by substituting a part of silica stone as a siliceous raw material with mullite while maintaining the sufficient compressive strength required for the ALC panel. It can be seen that the amount of silica stone used can be reduced as it is.

Claims (1)

A manufacturing method for producing a lightweight cellular concrete panel by curing an ALC slurry containing a siliceous raw material mainly composed of silica stone and a calcareous raw material.
A part of the silica stone constituting the siliceous raw material is replaced with mullite.
The content of the mullite with respect to the total content of the silica stone and the mullite in the siliceous raw material is set to more than 10% by mass and 15% by mass or less .
By extending the autoclave curing time, the same amount of tobamolite as when a part of silica stone is not replaced with mullite is generated.
A method for manufacturing lightweight cellular concrete panels.