JPH02221172A - Production of lightweight inorganic hardened body - Google Patents

Abstract

PURPOSE:To reduce the amt. of bubbles of a large diameter contained in a hardened body and to obtain a hardened body having high compressive strength by adding a specified amt. of silica fume and a high performance water reducing agent to hydraulic inorg. powder when a hardened body is produced by a prefoaming method. CONSTITUTION:Hydraulic inorg. powder is blended with 5-100wt.% silica fume and a high performance water reducing agent, a prescribed amt. of water is further added and they are mixed to obtain a mixture. A foaming agent is blended with water in a prescribed ratio and this blend is foamed with a foaming machine to form bubbles. These bubbles are added to the mixture so that a lightweight inorg. hardened body having prescribed bulk specific gravity is obtd., they are well kneaded and this kneaded material is poured into a mold and cured. A hardened body obtd. by this method contains nearly uniformly dispersed bubbles of a small diameter and has remarkably high compressive strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [1. Field of Industrial Application] The present invention relates to an improvement in a method for producing a lightweight inorganic cured body by a preform (pre-foaming) method.

[2. Prior art] A lightweight inorganic hardened material produced using a foaming agent, such as aerated concrete, is an excellent building material that has properties such as noncombustibility, fire resistance, heat insulation, and light weight. Demand is high.

Known methods for producing the lightweight inorganic cured body include a preform method, a migustoform method, and an afterform method.

The preform method that we are focusing on in this application involves mixing a foaming agent and water in advance in a foaming machine to create air bubbles, and then combining the air bubbles with separately created hydraulic inorganic powder such as cement and water. This method involves kneading it with a mixture, pouring it into a mold, and curing and hardening it. The preform method is widely practiced because the bulk specific gravity of the cured product can be freely adjusted by adjusting the amount of bubbles mixed in, and because the kneaded product can be easily manufactured on-site.

Specifically, a mixture of Portland cement, filler aggregate, a compound with organic fibers added if necessary, and water, and a natural protein-based foaming agent such as casein, glue, albumin, etc. A method of producing a lightweight inorganic cured body by kneading the bubbles obtained by stirring a carboxylic acid-based bubble stabilizer and water, molding the obtained kneaded product by conventional means, and curing is disclosed in JP-A-63- No. 295,487.

[30 Problems to be solved by the invention] The conventional method is as follows:
By using a special bubble stabilizer, the foam breakage rate and water absorption rate, which indicates the number of open cells, were each reduced by approximately half, making this a reasonably effective technology.

However, when we closely observe the lightweight inorganic cured material manufactured by conventional methods, we find that it still contains a considerable amount of so-called large-diameter cells and elongated open cells, which are formed by the coalescence of multiple cells, and this causes compression. The intensity was lowered.

Therefore, when trying to manufacture a cured body of a certain size as a building member, the strength is insufficient, and conversely, when trying to secure the required strength, it is necessary to significantly increase the wall thickness of the cured body. As can be seen from this example, the use of cured products made by conventional methods was limited due to their lack of strength, so the development of a method for producing lightweight inorganic cured products with high compressive strength has been awaited.

[Means for solving the 40 problems] Therefore, the present inventors conducted research on a method for further reducing the large-diameter cells and open cells, which are the cause of the decrease in the compressive strength of lightweight inorganic cured bodies. If you add silica hume and a high performance water reducer to hydraulic inorganic powder,
The present invention was completed based on the finding that the large-diameter bubbles, etc. in the produced cured product were significantly reduced, and the compressive strength was also significantly improved.

That is, the gist of the present invention is to knead bubbles created by stirring a foaming agent and water in advance into a mixture of hydraulic inorganic powder and water, mold the obtained kneaded product, and cure it. The method for producing a lightweight inorganic cured body is characterized in that 5 to 100% by weight of silica fume and a high performance water reducing agent are added to the mixture based on the powder.

The present invention will be explained in detail below.

The silica hume used in the present invention is generally commercially available. The silica hume usually contains 90% by weight or more of SiO□, contains amorphous, is nearly spherical, and is an ultrafine powder with an average particle size of about 0.1 to 0.2 μm.

The amount of silica hume added is 5% to the hydraulic inorganic powder.
~100% by weight, preferably 10-3°0% by weight
It is. If the amount added is less than 5% by weight, the air bubbles in the kneaded material may collapse, or large-diameter cells or open cells may form in the cured product, and the improvement in compressive strength will not be as great as that of 100%. If it exceeds % by weight, it is not preferable because workability is significantly deteriorated (and compressive strength is also lowered).

The high performance water reducing agent may be appropriately selected from those commonly used in the production of cement and concrete, such as β-naphthalene sulfonic acid condensate salts, melamine resin sulfonic acid formalin condensate salts, and the like.

The amount added is 0.3 to 3.5 to the total amount of hydraulic inorganic powder and silica hume (hereinafter referred to as solid content).
Weight % is appropriate. If the amount is less than 0.3% by weight, the effect of addition is low. There is no problem with increasing the amount added, but even if it is added in an amount of 3.5% by weight or more, a water reduction effect corresponding to the amount added cannot be expected and it is uneconomical.

In the present invention, it is essential to use the above-mentioned silica hume and a high performance water reducing agent in combination, and no effect can be obtained without either of them.

Next, other raw materials will be collectively explained.

As the hydraulic inorganic powder, various Portland cements, mixed cements, etc. are used, and as the foaming agent, the above-mentioned protein-based surfactants such as sodium alkylhenzenesulfonate are used. As the foaming agent, a protein-based foaming agent is preferred.

Next, a manufacturing process of a lightweight inorganic cured body using the above raw materials will be explained.

Hydraulic inorganic powder, silica hume and a high performance water reducer in the proportions mentioned above are blended, and water is added to 12% of the solid content.
~35% by weight was added and mixed to make a mixture, and on the other hand, a foaming agent and water were mixed in a ratio of 1:10 to 30 (weight ratio) and foamed using a foaming machine to remove air bubbles. to make.

After adding air bubbles to the mixture so as to obtain a lightweight inorganic cured product having a designed bulk specific gravity, the mixture is sufficiently kneaded.

The obtained mixture is poured into a mold and cured. As the curing method, any of the conventional moist air, steam, and autoclave curing methods may be used.

In the present invention, other materials such as cement admixtures, aggregates, fibers, etc. may be added to the raw material within the range permitted by the required bulk specific gravity and compressive strength of the cured product.

[50 Effects] Although it is currently unclear what effects the silica hume and high-performance water reducing agent used in the present invention have during kneading and curing processes, it is assumed that they have the following effects. do.

The silica fume, which is nearly spherical and has a microscopic diameter, helps disperse the hydraulic inorganic powder and the air bubbles, which have a large difference in specific gravity, through a bearing effect during kneading of the mixture and air bubbles, and during the curing process, it becomes amorphous. portion quickly dissolves and reacts with the powder to form a matrix around the bubbles. Therefore, during kneading, by preventing the bubbles from bursting or coalescing with each other to increase the diameter or become continuous, the fine bubble diameter when foamed can be maintained as it is, and the bubbles can be kept in the matrix. It is believed that this has the effect of uniformly dispersing the water. This can be seen from the fact that, as shown in Table 1, the cell diameter in the cured product is extremely biased towards the smaller side.

It is also certain that the above effects occur when silica hume is present in the presence of superplasticizers. The reason for this is, as shown in Comparative Example 4 in Table 1, when only silica hume is added, the amount of water needs to be significantly increased in order to maintain workability. In such a case, the bubbles tend to increase in diameter and become continuous as described above during kneading, and what is worse is that the bubbles become unevenly distributed in the cured product. As a result, the compressive strength is extremely reduced. Therefore, it seems that the superplasticizer has a promoting effect on silica hume.

As described above, the present invention takes effect only when silica hume and a high performance water reducing agent are used in combination.

[6, Examples] Examples 1 to 5, Comparative Examples 1 to 4 Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) was used as the hydraulic inorganic powder, and silica hume, a high performance water reducer, a bubble stabilizer, and water were added to it. They were blended in the proportions shown in Table 1 and mixed according to a conventional method to prepare respective mixtures.

On the other hand, a protein-based foaming agent (“Proform” manufactured by Saikoku Sho Company)
) was added to 20 times (by weight) water and forcefully stirred with compressed air to create bubbles.

The air bubbles were added to the mixture to achieve the bulk specific gravity target (air-dried) shown in the same table, and thoroughly kneaded with an Omnimixer (manufactured by Chiyoda Kako Co., Ltd., trade name).

After pouring the obtained kneaded material into a cylindrical mold, it was immediately steam-cured (held at 65° C. for 5 hours).

After that, it was left to cool, demolded, and each specimen (diameter 10
x height 20 cm) was obtained.

After measuring the bulk specific gravity (air-dried) and compressive strength of each specimen, one of the specimen specimens was cut with a diamond cutter, and the canted surface was measured for bubble distribution using an optical microscope. The obtained results are also listed in the same table.

[79 Effects of the Invention] The present invention is a method for producing a lightweight inorganic cured body by a preform method in which a specific amount of silica hieme and a high performance water reducing agent are added when mixing hydraulic inorganic powder and water. The cured product obtained by this method has microscopic air bubbles almost uniformly dispersed, and has extremely high compressive strength, far exceeding the lightweight inorganic cured product produced by the conventional method. There is. Furthermore, since the configuration of the present invention is simple, it is easy to put it into practical use.

Claims (1)

[Claims] (1) In a method for manufacturing a lightweight inorganic hardened body, which is made by kneading air bubbles created by foaming a foaming agent in advance into a mixture of hydraulic inorganic powder and water, shaping and curing the mixture, the powder is A method for producing a lightweight inorganic cured body, comprising adding 5 to 100% by weight of silica fume and a high performance water reducing agent to the mixture.