JPH0566908B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an improvement in a method for producing steam-cured lightweight cellular concrete (hereinafter abbreviated as ALC). [Prior technology] ALC is a slurry made by adding water and additives such as aluminum powder to calcareous raw powder such as lime and cement and silicic acid raw powder such as silica sand and silica stone, and then foaming and semi-slurry. It is manufactured by plasticizing it, then transferring it to an autoclave and curing it with high temperature and high pressure steam. ALC manufactured in this way uses a large amount of natural raw materials such as silica stone, so care must be taken to control the quality of the raw materials in order to guarantee and improve the physical performance and durability required as a building material. be. The most important thing when manufacturing ALC is
The objective is to uniformly produce a large amount of highly crystalline tobermorite in the product. For this reason, the weight ratio of the total lime content to silicic acid content (hereinafter abbreviated as C/S ratio) of the raw material is usually controlled to be 0.45 to 0.80. If the C/S ratio is outside the above range, hydrates with low crystallinity will form in some parts of the product, inhibiting the formation of tobermorite with high crystallinity, and therefore the compressive strength of the product will decrease and durability will deteriorate. It also becomes weaker. In addition, impurities such as alkali components and alumina components contained in raw materials may also be affected depending on their content.
Even if the C/S ratio is 0.45 or higher, low-crystalline hydrates will be produced, which will eventually interfere with the production of tobermorite and reduce the physical properties and durability of the product, so quality control of raw materials is required. is strictly followed. As a method of suppressing the formation of the aforementioned low-crystalline hydrates, in recent years mineral amimina substances such as kaolin, granulated blast furnace slag, etc. have been used in an amount of about 2 to 4% by weight based on the total solid content of the raw materials. It is being added. Although the addition of kaolin and the like improves the compressive strength to a certain extent, it has the disadvantage that the bubbles become disordered during the foaming stage, which increases the water absorption rate of the product, which also increases the cost. There is a point. Regarding raw materials, it has been found that using silicic acid raw materials with an alkaline content of 1% by weight or less, preferably 0.0% by weight or less, alleviates the above-mentioned drawbacks, but it is only possible to control the main raw materials. Currently, sufficient results have not been obtained in this regard. [Problems to be Solved by the Invention] The purpose of the present invention is to produce an ALC that does not have the above-mentioned drawbacks and stably exhibits desirable physical properties even when the blending ratio of raw materials and C/S ratio is lowered to about 0.40. The purpose is to provide a method. [Means for Solving the Problems] In order to achieve this objective, the inventor of the present application has conducted extensive research and found that the content of silica stone, which is the main raw material of ALC, has been improved by reducing the content of alumite contained as an impurity in the silica stone. ALC is produced by using a limited amount of 1.6% by weight or less, and following a conventional method. [Operation] In the method of the present invention, the main raw material, silica stone, is
The reason why the content of alumite (K ₂ O・3Al ₂ O ₃・4SO ₃・6H ₂ O) contained as an impurity in the silica stone is limited to 1.6% by weight or less is that If you use a substance with a content of 1.6% by weight or more,
This has a subtle effect on the hydrothermal reaction process,
This was determined based on the experimental findings that even when the C/S ratio is set to a high value of 0.6 to 0.8, highly crystalline tobermorite cannot be obtained, and the physical properties of ALC, particularly the compressive strength, are significantly deteriorated. The alumite content in silica stone is usually analyzed to be in the range of 1.0 to 3.0% by weight, depending on the place of production. It is not clear why thermal synthesis is inhibited and the production of highly crystalline tobermorite is prevented, but for example, during the transition from calcium silicate hydrate produced in the ALC manufacturing process to crystalline tobermorite. ,
It is thought that the alumite decomposes and the dissolved ions subtly influence the formation of tobermorite. According to the method of the present invention, it is possible to reliably obtain ALC with sufficient physical properties without adding any extra additives when the C/S ratio is 0.4 or more. [Example] Examples will be described below. Example C/S silica with an alumite content of 0.1 to 2.8% by weight, quicklime, and the main raw materials for Portland cement
ALC is produced by adding a predetermined amount of calcium sulfate, water, a small amount of aluminum powder (0.063 parts by weight), and usual additives to the mixture so that the ratio becomes a predetermined value. Compressive strength is JIS
According to Section A-5416-7, tobermorite was identified by X-ray diffraction of target Cu. The results are shown in Tables 1 and 2 in comparison with comparative examples.

[Table] Table note *To quantify the content of alum in silica, add each predetermined amount of pure alum to silica, and use the intensity of the main peak (2θ = 30℃) by X-ray diffraction to calculate the calibration curve. Each sample was subjected to X-ray diffraction using the same procedure, and this was converted to determine the quality. As is clear from Table 1, when the blending ratio of raw materials was kept the same and only the alumite content of silica stone was varied, the compressive strength of the bequest with the same grade of 1.8% by weight was the expected value of 40.0Kgf. /cm ² , but other than that, sufficient compressive strength was obtained and the results of X-ray diffraction were also satisfactory.

〔Effect of the invention〕

According to the present invention, ALC with good physical properties can be produced without adding any additives for improving physical properties or without strictly controlling the C/S ratio.

Claims (1)

[Claims] 1. In a method for producing steam-cured lightweight cellular cocrete whose main raw materials are calcareous raw materials such as lime and cement and silicic raw materials such as silica sand and silica stone, 1.6% by weight or less of alumite is contained as an impurity in the silica stone. An ALCB manufacturing method characterized by using a silicic acid raw material containing.