JP2001302327A - Production process of alc(autoclaved lightweight concrete) excellent in water repellency - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ALC production process by which ALC excellent in water repellency can simply be produced without increasing the amount of silicone oil added, and concurrently while using a recycled raw material as much as possible from the view point of resource conservation. SOLUTION: This production process comprises: adding a recycled raw material, an aluminum powder used as a gas-generating agent, silicone oil and water to a main raw material consisting of a siliceous raw material and a calcareous raw material, and mixing them together to form a raw material slurry; casting the raw material slurry into a form to form a semi-hardened body; and thereafter, subjecting the semi-hardened body to high temperature and high pressure steam curing in an autoclave; wherein as the recycled raw material, powdery ALC waste which is obtained by grinding an ALC waste material and drying the ground ALC waste material, preferably in such a way that the water content of the powdery ALC waste is reduced to 10-15 wt.%, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing lightweight cellular concrete (hereinafter simply referred to as ALC) suitable for a panel to be attached to an outer wall or a floor of a building, and particularly to a method for producing ALC having excellent water repellency.

[0002]

2. Description of the Related Art To manufacture ALC, a siliceous raw material such as silica stone and a calcareous raw material such as cement and quick lime are used as main raw materials, and the raw material is repeatedly added thereto, and aluminum powder as a foaming agent and water are added thereto. This raw material slurry is poured into a mold, foamed and semi-cured. Next, the semi-cured body is cut into a predetermined shape with a piano wire, transferred to an autoclave, and subjected to high-temperature and high-pressure steam curing to thereby perform ALC.
Is obtained.

[0003] The ALC manufactured in this manner is lightweight and excellent in heat insulation because it contains small air bubbles having a diameter of about 1 mm. In addition, it is excellent in fire resistance and workability. It has been widely used for floors, partitions, etc.

[0004]

When such an ALC is used in a cold region, there has been a problem that the ALC surface is liable to peel or crack, that is, a problem of so-called frost damage. The cause of the frost damage is that there are many bubbles and pores inside the ALC and the water absorption is as high as 25% or more.

[0005] That is, ALC has a large number of small bubbles having a diameter of about 1 mm formed in the foaming stage and pores of 1 µm or less generated during hydration of cement or curing in an autoclave. Therefore, the water absorbed by the ALC from inside and outside the room enters the air bubbles through the pores due to the capillary phenomenon, and the volume change of freezing and thawing is repeated, so that ALC is repeated.
Peeling and cracking occur on the surface.

Therefore, conventionally, a method of adding silicone oil to a raw material slurry has been generally performed for the purpose of imparting water repellency to ALC by lowering the water absorption of 25% or more. However, since silicone oil is expensive, a method of exhibiting water repellency while reducing the amount of addition as much as possible, and further improving the water repellency by changing the molecular weight, viscosity, type of functional group, etc. of the silicone oil. Various studies, such as methods, have been conducted.

[0007] On the other hand, in the production of ALC, ALC waste powder obtained by pulverizing ALC waste material that does not become a product is repeatedly used as a raw material. However, due to recent demands for resource saving and environmental pollution due to industrial waste. It has become important to reuse this ALC waste material repeatedly as a raw material.

However, if the waste powder obtained by pulverizing the ALC waste material is repeatedly reused as a raw material, the physical properties of ALC tend to become unstable, and in particular, with the increase in the amount of ALC waste powder added,
It has been found that even if silicone oil is added, improvement in the water repellency of ALC cannot be obtained.

The present invention has been made in view of such conventional circumstances,
To provide an ALC production method capable of easily producing an ALC having excellent water repellency without increasing the amount of silicone oil added from the viewpoint of cost and simultaneously using as many raw materials as possible from the viewpoint of resource saving. With the goal.

[0010]

In order to achieve the above-mentioned object, the present invention provides a method for producing ALC, which comprises repeating a raw material, a repeating raw material, aluminum powder as a foaming agent, A method of ALC in which a raw material slurry is prepared by adding and mixing oil and water, and the raw material slurry is injected into a mold to form a semi-cured body, and then the semi-cured body is cured at a high temperature and a high pressure in an autoclave. Wherein the ALC waste powder obtained by pulverizing and drying the ALC waste material is used as the repetitive raw material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A repetitive raw material conventionally used is an ALC waste powder obtained by simply pulverizing an ALC waste material, and has a water content of about 30 to 40% by weight. On the other hand, in the ALC production method of the present invention, not only the ALC waste material is ground but also the ALC waste powder reduced in moisture content by drying simultaneously or thereafter, preferably having a moisture content of 10 to 15%. A dried to% by weight
Use LC waste powder.

As described above, the use of ALC dust powder having a reduced water content by repeatedly pulverizing and drying as a raw material, together with the addition of silicone oil, makes it possible to reduce the AL content.
The reason why the water repellency of C is improved is considered as follows.

That is, the addition of silicone oil makes the pore surface of ALC water-repellent and inhibits the infiltration of moisture. However, by further increasing the fineness of the pore diameter, the intrusion of moisture is physically inhibited. Effect becomes higher. Here, the pore diameter fineness is a ratio of the sum of the cumulative porosity in each specified pore diameter range to the total pore amount as shown in the following formula 1, and is an index indicating the fineness of the pore diameter distribution. . The larger the value of the fine pore diameter is, the more the distribution of the fine pores having a small pore diameter is.

[0014]

[Formula 1] Fine pore diameter = {(pore amount of 32 to 100}) +
(Pore amount of 32 to 316 °) + (pore amount of 32 to 1000 °) + (pore amount of 32 to 10,000 °)｝ ÷ (32 to
10000 細孔 total pore volume)

On the other hand, in the production of ALC, it is known that the mixing ratio of water and the solid raw material of the raw material slurry, that is, the water ratio, greatly affects the pore structure among various physical properties of ALC. By lowering the water ratio, the above ALC
Can be increased, that is, the ratio of pores having a small pore diameter can be increased.

However, as in the prior art, when ALC dust powder that has been repeatedly pulverized as a raw material and is not dried is used, if the raw material slurry is adjusted at a water ratio that estimates the water content of the ALC dust powder, The amount of water to be mixed decreases, and as a result, the viscosity of the raw material slurry increases.

Therefore, when the amount of water is increased to lower the viscosity of the raw material slurry, the fineness of the pore diameter becomes small, which causes insufficient water repellency even when silicone oil is added. Further, since the water content of the ALC dust powder changes within a range of about 30 to 40% by weight due to a change in climate or the like, it was more difficult to control the water ratio under a constant condition.

On the other hand, when ALC dust powder dried at the time of pulverization is used as a raw material repeatedly according to the method of the present invention, its water content becomes constant at a low value of 10 to 15% by weight, and a predetermined water content is obtained. Since the amount of water added to and mixed with the raw material slurry in the ratio can be made larger than in the case of the undried ALC dust powder, the viscosity of the raw material slurry does not increase. As a result, a desired pore diameter fineness can be obtained by controlling a predetermined water ratio, and ALC having better water repellency can be obtained without increasing the amount of silicone oil added.

[0019]

EXAMPLE A silica raw material of 44% by weight and a calcareous raw material of cement of 27% by weight, quick lime of 4% by weight, and gypsum of 5% by weight as main raw materials were repeatedly used, and the raw materials were repeated at 19% by weight (weight in a standard dry state). 0.07% by weight of aluminum powder as a foaming agent, and 0.4 of silicone oil
% By weight, and water was added to prepare a raw material slurry.

As the repetitive raw materials, an ALC waste powder was used at the same time as the ALC waste material was pulverized, and an ALC waste powder which was only pulverized but not dried was used. The amount of water to be added is 0.1% by weight of water relative to the weight of the solid powder raw material (water ratio).
It was varied in the range of 60 to 0.66.

Each of the above raw material slurries is cast at a casting temperature of 42 to
Injected into the mold at 43 °. At that time, the viscosity at the time of injecting the raw material slurry was measured as a casting viscosity. Thereafter, the semi-cured product was taken out of the mold, subjected to high-temperature and high-pressure steam curing in an autoclave, and the pore amount and the water absorption (volume%) of each obtained ALC product were measured. The results obtained are shown in Table 1 below together with the type, water content (% by weight) and water ratio of the ALC dust powder, which is a repeated raw material.

The amount of pores was measured by a commonly used mercury intrusion method, and the pore diameter fineness was calculated from the obtained data in accordance with the above formula 1. The water absorption was measured using a cube having a side of 10 cm as a test sample, and weighing the test sample in a standard dry state at W ₁ , water of 20 ± 2 ° C. for 24 hours, and then absorbing the test sample. The weight of W was calculated as W ₂ , and the density of the test piece was defined as ρ.

[0023]

## EQU2 ## Water absorption (volume%) = {(W ₂ −W ₁ )} W ₁ }
× ρ × 100

[0024]

[Table 1]ALC waste powder Casting viscosityALC characteristics sample Drying Moisture content Water ratio (dPa / s) Fine pore diameter Water absorption  1 No drying 36.2% 0.60 4.8 2.51 14.2% 2 No drying 35.7% 0.62 3.9 2.44 15.9% 3 No drying 34.9% 0.64 3.1 2.10 17.6% 4 No drying 30.6% 0.66 2.7 1.87 19.8% 5 Dry 10.6% 0.60 3.4 2.74 8.2% 6 Dry 14.7% 0.62 2.6 2.61 9.6% 7 Dry 12.8% 0.64 2.1 2.55 9.8% 8 Dry 13.0% 0.66 1.8 2.48 10.9%

From the above results, at the same water ratio, the sample obtained by drying the ALC dust powder, which is a repetitive raw material, has a lower casting viscosity than the sample not dried, and the obtained ALC has a finer pore diameter. You can see it gets bigger. In addition, it can be seen that the larger the ALC of the fine pore diameter, the lower the water absorption rate and the higher the water repellency.

In the above embodiment, the addition amount of the ALC dust powder, which is a repetitive raw material, is fixed.
If the water absorption is within the allowable range, the amount of the repeated raw material can be further increased.

[0027]

According to the present invention, the repeated raw material A
ALC with excellent water repellency, using a simple method to dry LC dust powder, without increasing the amount of silicone oil added, and at the same time using as much of the raw material as possible to save resources.
Can be manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 18:16 C04B 26:32) 26:32) 111: 27 111: 27 111: 40 111: 40 E04C 2 / 46 C

Claims (2)

[Claims] 1. A raw material slurry is prepared by adding a repetitive raw material, an aluminum powder of a foaming agent, silicone oil and water to a siliceous raw material and a calcareous raw material as main raw materials,
After the raw material slurry is poured into a mold to form a semi-cured body, the semi-cured body is cured in a high temperature and high pressure steam in an autoclave by the ALC method. A obtained by drying
A method for producing ALC, comprising using LC waste powder. 2. The method for producing ALC according to claim 1, wherein the water content of the ALC dust powder is adjusted to a range of 10 to 15% by weight by drying.