JPH07187743A - Light-weight aerated concrete compositioon - Google Patents

Abstract

PURPOSE:To obtain a light-weight aerated concrete composition excellent in fluidity and minuteness of foams by compounding a siliceous raw material, a calcareous raw material, a blowing agent, water, a salt of a condensate of melamine-sulfonic acid with formaldehyde and a water-soluble polymer. CONSTITUTION:This light-weight aerated concrete composition is obtained by compounding (A) a siliceous raw material (e.g. silica sand), (B) a calcareous raw material (e.g. cement), (C) a blowing agent (e.g. alyminum powder), (D) water, (E) a salt of a condensate of melamine-sulfonic acid with formaldehyde and (F) a water-soluble polymer as essential components. A nonionic cellulose ester (e.g. methyl cellulose), polyethylene glycol, etc., is preferably used as the component F. Further, preferable compounding ratios of the component E and, the component F based on the total of the component A and the component B are respectively 0.01-1% and 0.005-0.1% in terms of the weight of solid components. The obtained composition is excellent in fluidity when cast, free from the remaining of large foams and capable of producing a light-weight aerated concrete having excellent quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight cellular concrete composition, and more particularly to a lightweight cellular concrete composition having excellent foam moldability.

[0002]

2. Description of the Related Art Light-weight cellular concrete is a calcareous raw material (lime, cement, etc.).
A mixture of siliceous and calcareous compounds is prepared by adding aluminum powder, etc. to a slurry prepared by adding water to a siliceous raw material (silica sand, fly ash), foaming it, or mixing the foam prepared beforehand to make it porous and then autoclave curing it. It is made and cured. These cured products are lightweight and have excellent heat insulating properties, fire resistance, and workability, and are therefore widely used in factory products for building members.

In the production of lightweight cellular concrete,
When pouring a slurry composed of main raw materials (calcium raw material and siliceous raw material), water and aluminum metal powder into a mold, a large amount of coarse bubbles are mixed due to physical factors. At this time, if the viscosity of the slurry is large, coarse bubbles remain as they are, and there is a problem of making the bubbles non-uniform. In particular, when reinforcing materials such as reinforcing bars are laid in lightweight cellular concrete, coarse cells cause defects after they cross the reinforcing bars, which causes reduction in product strength.

In order to improve the problem of slurry viscosity,
A method of adding a naphthalene sulfonic acid type dispersant or a method of adding a polycarboxylic acid type dispersant (Japanese Patent Laid-Open No. 63-40780).
No.) is being tried. However, if the fluidity at the time of pouring the mold is secured, the slurry viscosity is too low, and coalescence of bubbles occurs at the time of foaming with aluminum, and as a result, coarse bubbles remain in the product to cause defects. Further, since the naphthalene sulfonic acid-based dispersant has a large surface tension, it has a problem that the bubble diameter becomes coarse, and the problem of forming defects on the reinforcing material has not been completely solved.

[0005]

As a result of considering the above problems, the present inventors have found that a lightweight cellular concrete composition having a low slurry viscosity at the time of pouring a mold and having uniform fine cells introduced at the time of foaming. To complete the present invention product.

[0006] That is, the present invention relates to a lightweight cellular concrete composition comprising siliceous and calcareous raw materials, a foaming agent, water, a melaminesulfonic acid formaldehyde condensate salt and a water-soluble polymer as essential components.

In the present invention, other than the melamine sulfonic acid formaldehyde condensate salt and the water-soluble polymer, it is prepared by a known method (for example, JIS A5416). Examples of calcareous raw materials include lime and cement, and examples of siliceous raw materials include silica sand, silica stone, fly ash, clay, brick,
Examples include blast furnace slag. Examples of the foaming agent include metal powder (aluminum powder, etc.) and surfactants.

The melamine sulfonic acid formaldehyde condensate salt used in the present invention may be a commercially available product,
For example, the product name Mighty 150V-2 (manufactured by Kao Corporation) can be mentioned. The amount of addition is preferably in the range of 0.01 to 1.0%, and more preferably in the range of 0.05 to 0.2% in terms of solid content weight% with respect to the total amount of the siliceous raw material and the calcareous raw material. If the addition amount is less than 0.01%, the dispersibility is not exhibited, and if it exceeds 1.0%, the particles are separated to cause significant bubble escape.

Examples of the water-soluble polymer used in the present invention include nonionic cellulose ester, polyethylene glycol, polyacrylic acid and polyacrylamide. Of these, nonionic cellulose esters are preferable, and methyl cellulose is more preferable. The amount of addition is preferably in the range of 0.005 to 0.1% in terms of solid content weight% with respect to the total amount of siliceous raw material and calcareous raw material.
The range of 0.01 to 0.05% is more preferable. The amount added
If it is less than 0.005%, the bubble diameter becomes nonuniform, and if it exceeds 0.1%, the viscosity of the slurry increases and coarse air bubbles entrapped during mold injection tend to remain, causing defects.

The melamine sulfonic acid formaldehyde condensate salt used in the present invention is widely used in concrete factory products as a high-performance water reducing agent which highly disperses a cement composition and has good bubble stability. This high dispersibility makes it possible to reduce the viscosity of the main raw material slurry and to remove coarse bubbles at the time of pouring the mold. Further, since a water-soluble polymer such as methyl cellulose has a thickening effect at high temperatures, it can increase the slurry viscosity when aluminum is foamed, and can hold fine bubbles uniformly. In this way, it is possible to remove the entrained air bubbles at the time of pouring the mold and produce a good quality lightweight cellular concrete in which fine air bubbles are uniformly introduced at the time of foaming. The above points are clearly different from the conventional method of homogenizing air bubbles with a naphthalenesulfonic acid-based dispersant or a polycarboxylic acid-based dispersant (for example, JP-A-63-40780).

Regarding the production of the lightweight cellular concrete of the present invention, it is possible to use a known dispersant in combination within a range that does not have an adverse effect. Examples of the dispersant include β-naphthalenesulfonic acid formaldehyde condensate or a salt thereof, alkylnaphthalenesulfonic acid sulfonic acid formaldehyde condensate or a salt thereof, ligninsulfonic acid or a salt thereof, oxycarboxylic acid or a salt thereof, polycarboxylic acid or Salt thereof, polyalkylcarboxylic anhydride or salt thereof
(For example, Japanese Examined Patent Publication No. 63-5346, Japanese Unexamined Patent Publication No. 62-83344, Japanese Unexamined Patent Publication No. 1-270550) and the like, which may be mixed in advance, or after blending one with the main raw material, or One may be blended with the main raw material and kneaded before the other is blended.

A suitable combination ratio is 5 to 95% by weight based on the melaminesulfonic acid formaldehyde condensate salt used in the present invention.

Other additives (materials) such as AE water reducing agent, superplasticizer, high performance water reducing agent, retarder, early strengthening agent, accelerator, foaming agent, foaming agent, defoaming agent, water retention agent , Thickeners, self-leveling agents, waterproofing agents, rust preventives, coloring agents, anti-mold agents, crack reducing agents, polymer emulsions, other surfactants,
It is also possible to use it in combination with a water-soluble polymer and glass fiber.

[0014]

According to the present invention, the fluidity at the time of pouring into the mold is excellent, the retention of coarse bubbles is suppressed, and the uniform and fine bubbles are stably maintained at the time of foaming. Lightweight cellular concrete can be produced.

[0015]

EXAMPLES The present invention will be specifically described below, but the present invention is not limited to these examples. In addition,% in the following examples is% by weight.

(1) The composition of the main raw materials is as shown in Table 1,
The main raw material slurry and the admixture were mixed by stirring. Form the mixed slurry into a formwork (400 mm × 300 mm × height 700 m) with reinforcing bars.
m) to a height of 300 mm and foamed about twice. After semi-curing, demolding, autoclave curing (100 atm, 180 ° C)
Was carried out for 15 hours to produce lightweight cellular concrete.

[0017]

[Table 1]

(2) The admixture used is shown below.

[0019]

[Table 2]

(3) Evaluation items 1. Flowability test (flow test) A cylinder (diameter 50 mm x height 50 mm) was placed on an acrylic plate kept horizontally, and the stirred mixed slurry was poured into the cylinder and then gently. The major axis and the minor axis of the slurry that was pulled up and spread on the acrylic plate were measured, and the average value was used as the flow value.

2. Measurement of bubble diameter distribution (image analysis) The produced lightweight cellular concrete was split and the number of bubbles in the cross section was measured.
(Per unit area) was measured by an image analyzer.
The amount of bubbles in the cured product is in the range of 20 to 50%.

3. Observation of Bubble State The state of bubbles in the cross section of the produced lightweight cellular concrete was visually observed and evaluated as follows. ◎ Fine bubbles are evenly distributed, and there are no defects on the reinforcing bar. ○ Fine bubbles are distributed uniformly, but some defects are visible on the reinforcing bar. × Coarse air bubbles enter, the air bubble diameter becomes non-uniform, and defects on the reinforcing bar occur. Table 3 shows the above measurement results.

[0023]

[Table 3]

From the above, it can be seen from Table 3 that the lightweight cellular concrete of the present invention has a large number of cells while maintaining the same fluidity as compared with the comparative example. In particular, since there are many fine bubbles of 0.5 mm or less, it is clear that a good quality lightweight aerated concrete with uniformly fine bubbles can be obtained.

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Claims (4)

[Claims] 1. A siliceous and calcareous raw material, a foaming agent, water,
A lightweight cellular concrete composition comprising a melamine sulfonic acid formaldehyde condensate salt and a water-soluble polymer as essential components. 2. The addition amount of the melamine sulfonic acid formaldehyde condensate salt and the water-soluble polymer is 0.01 to 1.% by weight of the solid content relative to the total amount of the siliceous raw material and the calcareous raw material.
The lightweight cellular concrete composition according to claim 1, which is 0% or 0.005 to 0.1%. 3. The lightweight cellular concrete composition according to claim 1, wherein the water-soluble polymer is one or more selected from the group consisting of nonionic cellulose ester, polyethylene glycol, polyacrylic acid and polyacrylamide. 4. The lightweight cellular concrete composition according to claim 3, wherein the nonionic cellulose ester is methyl cellulose.