JP3234290B2 - Lightweight cellular concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autoclave-cured lightweight cellular concrete (hereinafter simply referred to as ALC) having a small cell diameter and improved drying characteristics. ALC is lightweight, has good workability, and has excellent workability, heat insulation, and fire resistance.
It is widely used for outer walls, roofs, partitions, etc. of steel-framed buildings such as offices and stores.

[0002]

2. Description of the Related Art Such an ALC has light weight and heat insulating properties by containing a large number of air bubbles in concrete. The average cell diameter of these ALCs is usually 0.5
１1 mm, but the average cell diameter of those manufactured by the preform method is as small as about 0.1 to 0.4 mm. ALC having a small bubble diameter is characterized in that not only the surface irregularities are small and the appearance properties are excellent, but also the water absorption rate is low.

[0003]

However, ALC having a small average cell diameter has a drawback that it is difficult to dry. That is, ALC retains moisture at the time of production immediately after production and has a high water content. Therefore, it takes time for the ALC having a small average cell diameter to dry the ALC after the production and construction, and such an ALC does not advance once it absorbs water even if the water absorption rate is low. For this reason, in the ALC having a small average cell diameter, a state in which the water content is large lasts particularly immediately after the start of use. Therefore, such ALC has the following disadvantages.

[0004] First, when ALC having such a high water content is used in a cold region, there is a problem that cracks occur in the panel when moisture in the panel freezes. In addition, ALC having a high water content has a problem that a carbonation reaction easily proceeds due to carbon dioxide in the air, and in extreme cases, shrinkage cracks are generated. Furthermore, if ALC with a high water content and a small drying rate is attached to the roof and then waterproofed with a plastic sheet or the like, and the ALC is heated by sunlight after waterproofing, the lower surface of the roof (inside the room) In addition, since water (water vapor) rapidly evaporated due to heating is difficult to escape, there is a problem that the waterproof sheet on the surface is pushed up and swelled, and in an extreme case, the sheet is destroyed and the waterproof effect is lost.

[0005]

Accordingly, the present inventor studied ALC having a relatively high drying rate despite having a small average cell diameter and excellent surface appearance and performance. It has been found that no problem occurs with ALC having a diameter, specific gravity and gas permeability, and the present invention has been achieved.

That is, according to the present invention, the average bubble diameter is 0.1 m.
m and less than 0.4 mm and gas permeability of 1 × 10 ^-6
cm ³ / sec ² or more ^{5 × 10 -5 cm 3 / sec} 2 below a is a specific gravity of lightweight concrete of less than 0.7 at 0.4 or more. The autoclaved light-weight aerated concrete board (ALC) of the present invention is usually made of calcareous raw materials such as quicklime and cement and siliceous raw materials such as silica stone as main raw materials and adding water and a foaming agent such as metal aluminum or a surfactant. Mix the foam produced using, cure after pouring into the mold,
It is formed by cutting. Thereafter, it is cured in saturated steam at about 10 atm to produce calcium silicate crystals to be produced.

The average cell diameter of the ALC of the present invention is 0.1 mm
It is necessary that the end is 0.4 mm. The average bubble diameter referred to here is the average of the diameters of circles equivalent in area obtained by observing the cut surface of ALC directly or by taking a photograph and determining the diameter of the bubble by image processing. If the average bubble diameter is 0.4 mm or more, the water absorption rate increases, and the frost damage resistance decreases. If the average bubble diameter is 0.1 mm or less, the gas permeability decreases.

The gas permeability of the ALC of the present invention is 1 × 10 ^-6.
cm ³ / sec ² or more 5 × 10 ^-5 cm ³ / should sec less than ^2. In the measurement of gas permeability of the present invention, a cylindrical sample having a bottom area of Scm ² and a height of Hcm ² is used, and air having a viscosity of μ poise is permeated with a pressure difference of ΔPg / cm ^{2 in} the axial direction of the sample. Assuming that the air flow rate at this time is Qcm ³ / sec, the gas permeability Kp can be obtained by the following equation.

[0009]

(Equation 1)

The gas permeability is 1 × 10 ⁻⁶ cm ³ / sec ²
If it is smaller, the drying rate of ALC is low. If the gas permeability is greater than 5 × 10 ⁻⁵ cm ³ / sec ² , the water absorption rate will increase and the heat insulation performance will decrease. Particularly preferably, the gas permeability is 3 × 10 ⁻⁶ cm ³ / sec ² or more.
× 10 ⁻⁵ cm ³ / sec ^{2 or} less. The drying speed was determined by cutting ALC into 4 × 4 × 16 cm, drying at room temperature until there was no change in weight, holding in water for 10 days, absorbing water, and drying in a room at 20 ° C. and a relative humidity of 65%. The change was measured and determined by the change in the weight percentage of water content per hour. The drying rate is preferably at least 0.6% by weight / hour, particularly preferably at least 0.65% by weight / hour.

In the present invention, the specific gravity of ALC is 0.4 to 0.5.
It needs to be 7. The specific gravity here and ALC
Is a specific gravity measured after taking out a portion having no reinforcing reinforcing bar and drying it to a constant weight in a dryer at 105 ° C. If the specific gravity is lower than 0.4, the strength of ALC is reduced, and it is likely to be broken during construction or broken during use after construction. Workability and heat insulation performance are reduced. Particularly preferably, the specific gravity is 0.45 or more and less than 0.6.

As a method for producing ALC of the present invention, for example, the following method can be adopted. As a raw material for producing ALC, conventionally used raw materials such as silica stone, lime, cement, and gypsum can be used. It is also possible to pulverize and recycle the product and add it to the raw material before use. As a means for containing bubbles, it is preferable to adopt a preform method in which bubbles produced by a surfactant solution are prepared in advance and mixed with a raw material mortar slurry. As the surfactant used in the preform method, a non-proteolytic surfactant such as a higher alkyl ether sulfate sodium salt is preferable.

[0013] Proteolytic surfactants usually used in the preform method are not preferred because of their low gas permeability. On the other hand, surfactants such as dodecylbenzene sulfonic acid are not preferred because the water absorption rate becomes too high. In order to produce a foam from a surfactant solution, a gas such as air and a surfactant solution can be obtained by dispersing and mixing while press-fitting into a cylinder filled with crushed stone, glass beads, Raschig rings or the like. The foam thus produced is added to the mortar slurry, and the amount to be added is appropriately set depending on the surfactant used, for example, in the case of higher alkyl ether sulfate sodium salt, 0.2 to 0.2
Foam is formed by an aqueous solution having a solid content of 0.5 wt%, and the foam is mixed with the raw material mortar slurry at a solid content of about 5 to 1%.
About 0 wt% is added.

Thereafter, the foam-containing mortar slurry is poured into a mold and cured. After reaching a predetermined hardness, it is released from the mold. After cutting and molding this cured mortar,
Cure in an autoclave.

[0015]

According to the above construction, the drying speed of ALC is increased despite the small bubble diameter.
After constructing the LC, it is possible to prevent adverse effects due to moisture retained inside the ALC. The reason why foam concrete with a small cell diameter and good gas permeability can be produced when a specific amount of foam produced from a specific surfactant is used is not well understood, but the stability of cells and the properties of mortar are related. it seems to do. It is considered that some of the small bubbles trapped in the mortar are connected to improve the gas permeability.

[0016]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

[0017]

EXAMPLE 1 A silica slurry (43 parts by weight of solid silica), 7 parts by weight of quicklime powder, 26 parts by weight of cement, 2 parts by weight of gypsum, and a slurry obtained by crushing and refining mortar that has been subjected to preliminary curing (solid content: 22 parts by weight) Parts by weight) and 64 parts by weight of water (including the water content in each slurry) were mixed for 2 minutes with a mixer equipped with stirring blades to produce a slurry. Higher alkyl ether sulfate sodium salt (the alkyl group has 10 carbon atoms and the average degree of polymerization of polyethylene glycol is 1.
The 1% solution of 5) and pressurized air were mixed and dispersed in a cylinder filled with Raschig rings to produce foam. 6 parts by weight of this foam and mortar slurry were mixed for 2 minutes using a ribbon mixer. The mortar slurry mixed with the foam was poured into a mold and kept at 60 ° C. to be cured. After reaching a predetermined hardness, it was released from the mold. After the cured mortar was cut and molded, it was cured in an autoclave in saturated steam at 180 ° C. The obtained lightweight aerated concrete is reduced to a diameter of 10
cm, 10cm in height and cut at 20 ° C, 60
% In a constant temperature / humidity chamber, and then measured for specific gravity and gas permeability. The specific gravity was 0.49 and the gas permeability was 1.0 × 10 ⁻⁵ cm ³ / sec ² . When the average bubble diameter was measured using an image analyzer, it was 0.25.
mm. Furthermore, this lightweight cellular concrete is 4 ×
It was cut into 4 × 16 cm, dried at room temperature until there was no change in weight, kept in water for 10 days, and allowed to absorb water. Then 2
Drying was performed in a room at 0 ° C. and a relative humidity of 65%, the change in weight was measured, and the drying rate was determined based on the change in water-containing weight% per hour. As a result, this lightweight cellular concrete has a capacity of 0.1 mm.
The drying rate was 67% by weight / hour. When the bending strength was measured, it was 15 kg / cm ² .

[0018]

Example 2 10 parts by weight of a foam made by a surfactant prepared in the same manner as in Example 1 was used, and water in the slurry was reduced by 6%.
Lightweight cellular concrete was produced in exactly the same manner as in Example 1 except that 0 parts by weight were added and that the mixing of mortar and foam was performed using a propeller type mixer. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.41 and the gas permeability was 1.4 × 10 ⁻⁵ cm ³ / sec ² . When the average bubble diameter was measured using an image analyzer, it was found that the average bubble diameter was 0.1.
23 mm. The drying rate was 0.73% by weight /
It was time. When this sample was cut into a cube having a side of 10 cm and floated on water, it floated even after 24 hours.

[0019]

Comparative Example 1 The amount of foam produced in the same manner as in Example 2 was 4
Lightweight cellular concrete was manufactured in exactly the same manner as in Example 2 except that the parts by weight were used and 66 parts by weight of water in the slurry were added. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.72 and the gas permeability was 0.6.
× 10 ^-7 cm ³ / sec ² . The average bubble diameter measured with an image analyzer was 0.20 mm. The drying rate was 0.48% by weight / hour.

[0020]

Comparative Example 2 Lightweight cellular concrete was produced in exactly the same manner as in Example 1 except that 5 parts by weight of the foam prepared in the same manner as in Example 2 was used and that 65 parts by weight of water in the slurry were added. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.60 and the gas permeability was 0.2 × 10 ⁻⁶ cm.
It was ³ / sec ^2. The average bubble diameter measured with an image analyzer was 0.20 mm. The drying rate was 0.58% by weight / hour.

[0021]

Comparative Example 3 15 parts by weight of the foam prepared in the same manner as in Example 2 were used, and 55 parts by weight of water in the slurry were added.
Except for the above, a lightweight cellular concrete was manufactured in exactly the same manner as in Example 1. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.35 and the gas permeability was 15 × 10 ⁻⁵ cm.
It was ³ / sec ^2. The average bubble diameter measured with an image analyzer was 0.27 mm. The drying rate was 0.53% by weight / hour. When the bending strength was measured, it was 6 kg / cm ^2, which was weak and easily chipped.

Table 1 shows the results of Examples 1 and 2 and Comparative Examples 1 to 3.

[0023]

[Table 1]

[0024]

Comparative Example 4 A foam was prepared in the same manner as in Example 1 using a 1% solution of dodecylbenzenesulfonic acid, and the same procedure as in Example 1 was repeated except that 10 parts by weight of the foam and 60 parts by weight of water were used. Lightweight cellular concrete was produced exactly as in 2. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.34 and the gas permeability was 3.5 × 10 ⁻³ cm ³ /.
It was sec ^2. When the average bubble diameter was measured using an image analyzer, it was 1.05 mm. The drying rate was 0.86% by weight / hour. When this sample was cut into a cube having a side of 10 cm and floated on water, the water absorbed and sank in one hour.

[0025]

Comparative Example 5 A foam was prepared in the same manner as in Example 1 using a 10% solution of a proteolytic surfactant, and 3 parts by weight of foam and 67 parts by weight of water were added. Lightweight cellular concrete was manufactured in exactly the same manner as in Example 1. Example 1
When the specific gravity and the gas permeability were measured in the same manner as described above, the specific gravity was 0.1.
49, gas permeability is 0.16 × 10 ⁻⁶ cm ³ / sec ²
Met. The average bubble diameter measured with an image analyzer was 0.25 mm. The drying speed is
0.58% by weight / hour.

[0026]

Comparative Example 6 A silica slurry (43 parts by weight of silica solids), 7 parts by weight of quicklime powder, 26 parts by weight of cement, 2 parts by weight of gypsum, and a mortar that had been subjected to preliminary curing was crushed and recycled (solid content: 22 parts by weight). Parts by weight) and 70 parts by weight of water (to which water in each slurry was added) was mixed for 2 minutes with a mixer equipped with stirring blades to produce a slurry. 0.07 parts by weight of aluminum powder was added thereto, and the slurry was mixed for 1 minute.
This mixed mortar slurry is poured into a mold,
And cured. After reaching a predetermined hardness, it was released from the mold. After cutting and molding this cured mortar, 18
Cured in an autoclave at 0 ° C. in saturated steam. When the specific gravity and the gas permeability were measured in the same manner as in Example 1, the specific gravity was 0.48 and the gas permeability was 3.9 × 10 ⁻⁶ cm ^3.
It was / sec ^2. When the average bubble diameter was measured using an image analyzer, the average bubble diameter was 0.72 mm, and there were many bubbles of 3 mm or more. The drying rate was 0.63% by weight / hour.

[0027]

The lightweight cellular concrete of the present invention has a high gas permeability and a high drying rate despite the small cell diameter, and has excellent frost damage resistance and durability that does not destroy the waterproof sheet at the time of roof construction. New AL with excellent workability
C can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 38/00-38/10 E04C 2/04

Claims (1)

(57) [Claims] An average bubble diameter of 0.1 mm or more and 0.4 mm
The gas permeability is less than 1 × 10 ⁻⁶ cm ³ / sec ^{2 and} less than 5
Lightweight cellular concrete with specific gravity of 0.4 or more and less than 0.7 that is less than × 10 ^-5 cm ³ / sec ²