JP2009057225A - Method for manufacturing autoclaved lightweight concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing ALC where ALC excellent in properties such as strength and the like can be stably manufactured whatever raw materials used in ALC production are blended. <P>SOLUTION: In the method for manufacturing autoclaved lightweight concrete where a siliceous raw material and a calcareous raw material are main raw materials, the accumulation 30% particle diameter of a silica stone in the main raw materials is adjusted according to a molar ratio Ca/Si in blended all raw materials. In that case, it is favorable that the accumulation 30% particle diameter of the silica stone in the main raw materials is adjusted to be satisfied with an equation denoted as Y=120-160X±10 when a molar ratio Ca/Si in the blended all raw materials is described as X and the accumulation 30% particle diameter of the silica stone in the main raw materials is described as Y μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing lightweight cellular concrete (ALC) used for building walls, roofs, floors and the like.

  Lightweight cellular concrete (ALC) has excellent properties that it contains bubbles and pores inside, has an extremely dry specific gravity of about 0.5, and is relatively light, yet has a relatively high strength. Thus, ALC is widely used as a building material and the like because it is lightweight and has relatively high strength and excellent fire resistance, heat insulation, and workability.

  The production of ALC is mainly made of siliceous raw materials such as silica and calcareous raw materials such as cement and quicklime, and water and additives such as aluminum powder as a blowing agent are added to the fine powder of these main raw materials to form a slurry. Thereafter, it is put into a mold and foamed by a reaction of aluminum powder, and semi-cured by a reaction of a calcareous raw material. Next, it cut | disconnects to a predetermined dimension and performs high temperature high pressure steam curing by an autoclave, and ALC is manufactured.

  It is the high temperature and high pressure steam curing by autoclave that develops the strength of ALC. In this curing process, calcium silicate hydrate tobermorite is generated from siliceous raw materials such as silica and calcareous raw materials such as cement and quicklime. In an autoclave, which is a tobermorite production process, it is widely known that dissolution of silica stones controls the reaction.

  Therefore, the particle size, single crystal size, purity, type and content of impurities, etc. of the silica have a great influence on the physical properties of the obtained ALC. In particular, it has been found that the particle size of quartzite affects the physical property values such as generation of crystal nuclei by fine particles, growth of crystals by medium particles, and aggregate effect due to remaining coarse particles. Therefore, various methods for producing ALC having excellent physical properties by regulating the particle size of silica have been studied.

  For example, Japanese Patent Laid-Open No. 59-128254 describes a method for adjusting the particle size of silica stone to 15 μm or less in weight average diameter, and Japanese Patent Laid-Open No. 4-197605 discloses silica sand from 2000 to 2,500 branes and 6,000 to 6,000. A method is described in which the distribution has a peak at 12,000 branes. Japanese Patent Application Laid-Open No. 2001-019571 discloses a method in which silica having an average quartz crystal grain size of less than 10 μm and 10-500 μm silica are mixed, the average quartz crystal grain size of the mixed silica is 15 to 300 μm, and 10 μm. A method has been proposed in which the mixing ratio of less than or equal to silica is 60% by weight or less.

However, in these conventional methods, the difference in the raw material composition used in ALC production is not considered at all. For this reason, a good silica particle size distribution may not be suitable for the production of a good ALC under some raw material blending conditions.
JP 59-128254 A JP-A-4-197605 JP 2001-019571 A

  An object of this invention is to provide the method which can manufacture stably ALC excellent in various physical properties, such as intensity | strength, irrespective of the raw material mixing | blending used by ALC manufacture.

  In order to achieve the above object, a lightweight cellular concrete manufacturing method provided by the present invention is a lightweight cellular concrete manufacturing method using a siliceous raw material and a calcareous raw material as main raw materials, and a cumulative 30% grain of silica stone in the main raw material. The diameter is adjusted according to the Ca / Si molar ratio in the total raw material composition.

  In the method for producing lightweight aerated concrete according to the present invention, when the Ca / Si molar ratio is X and the cumulative 30% particle size of silica is Y (μm), the relationship is Y = 120−160X ± 10. It is preferable to adjust to.

  According to the present invention, ALC excellent in various physical properties such as strength can be stably produced regardless of the raw material composition used in ALC production.

In the high temperature and high pressure steam curing process, tobermorite, which is a calcium silicate hydrate, is produced from a siliceous raw material such as silica and a calcareous raw material such as cement and quicklime, and the strength of ALC is expressed by this tobermorite. Tobermorite is 5CaO · 6SiO ₂ · 5H ₂ O in chemical formula, and the theoretical value of the Ca / Si molar ratio is 5/6 = 0.83. In the ALC industrial production, the Ca / Si molar ratio should be set smaller than the theoretical value 0.83, that is, in the range of 0.3 to 0.7 in order to shorten the time required for autoclave curing. Is almost.

  The present inventor evaluated ALC samples produced by appropriately using silica stones having different particle sizes in various raw material blends. As a result, it was found that the range of the appropriate silica particle size in the main raw material varies depending on the Ca / Si molar ratio in the total raw material blend. That is, when the Ca / Si molar ratio is as low as about 0.3 to 0.4, a coarse silica particle size with a small amount of dissolution in the autoclave curing is suitable, and conversely, the Ca / Si molar ratio is 0.6. When it was as high as about 0.7, it was found that a fine silica particle size with a large amount of dissolution in the autoclave curing was suitable.

  In addition, as an index of silica particle size, there are various values such as brane value, cumulative 20%, cumulative 30%, cumulative 40%, cumulative 50%, cumulative 60% particle size, or frequency of 30μm, 40μm, 50μm or less As a result of examining various indices, it was found that a cumulative 30% particle size is most suitable as an index. Here, the cumulative 30% particle size means the particle size distribution when the weight at each particle size is sequentially accumulated from the fine particle side in the silica particle size distribution, and the accumulated weight ratio reaches 30% of the total weight. Means diameter.

  That is, when the Ca / Si molar ratio in all raw materials is X and the cumulative 30% particle size of silica in the main raw material is Y (μm), the relationship of Y = 120−160X ± 10 is satisfied. It is preferable to adjust the cumulative 30% particle size of the silica in the main raw material according to the Ca / Si molar ratio in the total raw material blend. In addition, the adjustment of the cumulative 30% particle size of silica can be easily adjusted by mixing two or more types of silica with different particle sizes.

  Silica stones produced from the same mine in Aichi Prefecture as a siliceous raw material were pulverized in advance with a ball mill and classified into five types of particle sizes. The cumulative 30% particle size of these five types of silica was 4.5 μm, 10.2 μm, 25.4 μm, 47.7 μm, and 85.4 μm, respectively. These five types of silica were mixed as appropriate to adjust the particle size so that an arbitrary cumulative 30% particle size was obtained.

  Next, according to the Ca / Si molar ratio in all the raw material mix | blends, it has each cumulative 30% particle size so that it may become each condition of Examples 1-38 and Comparative Examples 1-29 shown in following Table 1. Silica stone, quicklime, ordinary Portland cement, and repeated raw materials were mixed. 60 parts by weight of water, a small amount of aluminum powder and a surfactant were added to 100 parts by weight of these solid raw materials, and kneaded to prepare a slurry.

  Each slurry was poured into a mold, foamed, semi-cured, cut, and then subjected to high temperature and high pressure steam curing for 6 hours in an autoclave at 180 ° C. and 10 atmospheres. Each of the obtained ALC blocks was molded into a 100 mm square cube, and the compressive strength was measured according to JIS A5416. The obtained compressive strength is shown in Table 2 below.

The standard value of ALC compression strength according to JISA5416 is 3.0 N / mm ² or more, but usually 4.0 N / mm ² or more is a standard for safety management. Therefore, in the evaluation of the compressive strength, 4.0 N / mm ² or more was determined as “appropriate” and less than 4.0 N / mm ² was determined as “unsuitable”. The results of Table 2 by this evaluation are plotted in FIG. 1 with “appropriate” as ◯ and “unsuitable” as x.

  From these results, it is recognized that an ALC having excellent properties such as compressive strength can be obtained by adjusting the cumulative 30% particle size of the raw material silica according to the Ca / Si molar ratio of all raw materials. That is, if the Ca / Si molar ratio of all raw materials is X and the cumulative 30% particle size of silica is Y (μm), the range of “suitable” in FIG. 1 is represented by Y = 120−160X ± 10. I understand.

It is the graph which plotted the relationship of Ca / Si molar ratio in an Example and a comparative example, and the accumulation 30% particle diameter of the used silica stone as (circle) in which evaluation of the obtained ALC was appropriate, and (x) inadequate.

Claims (2)

  In the method for producing lightweight aerated concrete using a siliceous raw material and a calcareous raw material as main raw materials, the cumulative 30% particle size of silica in the main raw material is adjusted according to the Ca / Si molar ratio in all raw material blends. A method for producing lightweight cellular concrete.   The light weight according to claim 1, wherein when the Ca / Si molar ratio is X and the cumulative 30% particle size of silica is Y (μm), the relationship is adjusted to Y = 120−160X ± 10. A method for producing cellular concrete.

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