JPH09110548A - Production of lightweight aerated concrete, apparatus therefor and lightweight aerated concrete produced by the same production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a lightweight aerated concrete capable of preventing occurrence of huge air bubbles, voids and cracks above the horizontal part of a reinforcing bar mat by a simple machine and apparatus by spraying air to the surface of a raw material slurry from above and waving the surface layer. SOLUTION: In an apparatus for producing a lightweight aerated concrete (ALC), for example, a frame 1 of a rectangular prism has 1,540mm width, 6,120mm length and 680mm height based on an inside dimension and an air spraying device 10 comprises a horizontal table 12 provided with eight nozzles 11 having 2mm bore diameter arranged at 180mm intervals in a row in parallel in the width direction. The air spraying device 10 is removable in parallel in the longer direction. After a slurry having an ordinary compounding at 46-48 deg.C is poured into a mold 1 having set a reinforcing bar mat 2, when the surface of the slurry reaches 20mm above the top edge part 2a of the reinforcing bar mat, a valve 15 is opened, air at 4kg/cm<2> is sprayed from the nozzles 11 on the surface of the slurry to wave the surface of the slurry. The air spraying device 10 is horizontally moved and the spray is completed. The raw material slurry is hardened into a semiplastic state to give an ALC panel.

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 referred to as ALC), and more specifically to a method for preventing the formation of giant bubbles or cavities or cracks on the ALC surface and in the ALC. Is.

[0002]

2. Description of the Related Art Generally, when manufacturing an ALC panel, first, a reinforcing bar mat in which reinforcing bars are welded in a net shape, or a reinforcing bar cage in which two or more reinforcing bar mats are fixed in a cage shape (hereinafter, simply referred to as a reinforcing bar mat) is used. ) Is set in the rectangular parallelepiped form as follows. That is, a plurality of pins are arranged vertically, one end of each of the pins is fixed to a plurality of pin bridges, the pins are suspended, and then a reinforcing bar mat is fixed to the other end of the pins.
Next, the pin bridge is horizontally suspended on the upper edge of the rectangular parallelepiped form, and the reinforcing bar mat is housed in the form so that the bottom of the reinforcing bar mat floats from the bottom of the form.

Next, aluminum powder is added as a foaming agent to a slurry obtained by adding aggregate, additives and water to Portland cement, and the raw material slurry (hereinafter, simply referred to as slurry) kneaded is placed in the above mold. Inject a fixed amount to foam. After the foaming is completed and the slurry is hardened into a semi-plastic state, the semi-plastic material is taken out from the mold. further,
The above semi-plastic material is cut into a desired size, charged into an autoclave, and steam-cured to obtain a product. However, in the process of foaming the slurry, so-called giant bubbles having a diameter of 2 mm or more, or even larger cavities or cracks may occur.

When these giant bubbles, cavities or cracks are exposed on the panel surface, the appearance of the product is impaired, and local repair is necessary or when repair is difficult, the product must be discarded and the product yield is increased. Lower. Further, if these defects are unevenly distributed in the panel, the strength of the panel is reduced. In particular, cavities are likely to occur in the upper part of the horizontal main bar of the reinforcing bar mat. The reason for the generation of this void is not always clear, but it is said to be as follows. That is, in the process of foaming the slurry, the horizontal portion of the reinforcing bar mat hinders the smooth rise of the surface of the slurry. As a result, it is said that giant bubbles are concentrated right above this horizontal reinforcing bar, or the water content in the slurry that is separated and separated falls out and becomes a cavity after the slurry is hardened. Especially at the end of foaming, the viscosity of the slurry increases, so
The above is most affected above the rebar located at the top. Then, in extreme cases, a part of the cavity may be exposed on the front surface of the panel, or the front surface of the panel may be cracked.

As a method for preventing the generation of such huge bubbles, cavities or cracks, there is (1) a method in which a skilled worker scrapes the surface of the slurry with a brush-like tool during foaming. Also, as another method, by a mechanical device,
(2) A method of preventing entrainment of air at the time of pouring the slurry, (3) A method of vibrating the mold or the reinforcing bar during pouring of the slurry or during foaming, and (4) JP-A-63-256405.
As described in JP-A-6-92751,
A method has also been proposed in which a stick is pierced from above during foaming, or the stick pierced is horizontally moved. However, the manual work of (1) above is troublesome, and (2),
The mechanical devices in (3) and (4) have a complicated structure and cost. Further, as described above, since a plurality of pin bridges are suspended horizontally at the upper edge of the mold, there is a problem that the operation for avoiding the position and performing the above method is troublesome.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to use a mechanical device having a simple structure, which is located above the rebar of the horizontal portion of the rebar mat, particularly at the top. The object of the present invention is to provide a method for manufacturing lightweight cellular concrete that prevents generation of huge bubbles or cavities or cracks, and a manufacturing apparatus for carrying out the method. Another object of the present invention is to provide a lightweight cellular concrete with few giant bubbles or cavities or cracks.

[0007]

Means for Solving the Problems The present invention achieves the above-mentioned object, and is obtained by injecting a slurry into a mold in which a reinforcing bar mat is set, foaming it, and hardening it into a semi-plastic state. In a method for producing a lightweight cellular concrete in which a semi-plastic material is steam-cured in an autoclave, when the surface of the slurry rises due to the foaming and exceeds the upper end of the rebar mat, the slurry is added from above the surface of the slurry. It is a lightweight cellular concrete produced by the method and a method for producing a lightweight cellular concrete, characterized in that air is blown onto the surface to cause the surface layer of the slurry to wave. Further, the present invention is a lightweight cellular concrete manufacturing apparatus having a formwork into which a reinforcing rod mat is set, a raw material slurry is injected, and an autoclave for steam curing a semi-plastic material in which the injected raw material slurry is hardened. An air blowing device for blowing air onto the surface of the mold is arranged above the upper edge of the mold so as to be movable parallel to the longitudinal direction of the upper edge of the mold. It is also a concrete manufacturing device.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing lightweight cellular concrete according to the present invention, when the surface of the slurry rises due to foaming and exceeds the upper end of the rebar mat, air is applied to the surface of the slurry from above the surface of the slurry. By spraying the surface layer of the slurry, preferably by vibrating and stirring the layer from the surface of the slurry to the upper end of the reinforcing bar mat, while preventing the water in the slurry from being generated separately. The expansion of the slurry due to the foaming gas can be made uniform to prevent generation of giant bubbles or cavities or cracks above the reinforcing bars in the horizontal part of the reinforcing bar mat, especially right above the reinforcing bars located at the top. it can. The time of blowing the air is a time when the surface layer of the slurry, preferably the layer from the surface of the slurry to the upper end of the reinforcing bar mat can be waved uniformly, and the surface of the slurry is
From the upper end of the rebar mat, preferably 10-40 mm,
More desirably, when it is sewn up to 20 to 30 mm,
Start blowing air. If the start time is too early or too late, the effect of blowing air is reduced.

The pressure and air volume of the air to be blown may be appropriately selected depending on (1) the diameter and number of nozzles, the height from the surface of the slurry, (2) the composition of the slurry, the temperature and the like. The blowing of air is completed before the foaming of the slurry is finished, when the air is blown while moving in the longitudinal direction of the mold and the movement is completed (usually about 60 seconds). The air blowing conditions employed to evenly wave the surface layer of the slurry, preferably the layer from the surface of the slurry to the upper end of the rebar mat, can be determined from the results of preliminary tests. FIG. 1 is a front view showing an embodiment of a part of the ALC manufacturing apparatus of the present invention. In FIG. 1, a reinforcing rod mat 2 is set in a rectangular parallelepiped form 1 by pins 3 and pin bridges 4. Further, in the air blowing device 10, the nozzles 11 are arranged in a row on a horizontal table 12 (in the direction perpendicular to the paper surface in the figure), and a plurality of receiver tanks 13 and a compressor 14 are provided on the upper surface of the table 12.
Are arranged.

Each of the nozzles 11 is connected to the receiver tank 13 via a valve 15 by piping so that high pressure air is jetted downward from the nozzles 11. The air blowing device 10 is suspended by a crane 16 and moved above the upper edge of the mold 1 in parallel with the longitudinal direction thereof. The nozzles 11 may be arranged in a plurality of rows instead of one row. Further, the receiver tank 13 and the compressor 14 may be fixed away from the table 12, and may be connected to the movable nozzle 11 by a pipe whose length can be changed. As described above, as the air blowing device 10, an inexpensive device having a simple structure can be used. The crane 16 does not need to be particularly provided, and an existing pin removing crane can be used. Furthermore, since air is blown to prevent the formation of huge bubbles or cavities or cracks, even if there is a pin bridge suspended on the formwork, the pin bridge does not hinder the air blowing operation.

[0011]

An embodiment of the present invention will be described below. Example 1 An ALC manufacturing test was conducted using the ALC manufacturing apparatus of the present invention shown in FIG. In FIG. 1, the rectangular parallelepiped mold 1 has inner dimensions of a width of 1,540 mm, a length of 6,120 mm, and a height of 680 mm. Further, the air blowing device 10 includes eight nozzles 11 having a diameter of 2 mm.
Are arranged in parallel with each other in the width direction on the horizontal table 12 at intervals of 180 mm. Then, the air blowing device 10 is configured to move the height of 280 mm above the upper edge portion 1a of the mold 1 in parallel to the longitudinal direction thereof.
Normal mixing was performed, and the slurry having a temperature of 46 to 48 ° C. was poured into the mold 1 in which the reinforcing bar mat 2 was set. After injection
When the surface of the slurry reaches 20 mm above the upper end portion 2a of the reinforcing bar mat due to expansion of the slurry due to foaming, the valve 15 is opened and the nozzle 11 blows air of a pressure of 4 kg / cm ² onto the surface of the slurry in the mold 1. Was sprayed on and the surface layer of the slurry was made to ruffle. Immediately before opening the valve 15, the compressor 14 was started and the receiver tank 13 was filled with high-pressure air.

The air blowing device 10 was moved horizontally at a speed of 120 mm / sec while the surface layer of the slurry was undulated. After performing the above movement over the entire length of the mold 1 (5
After 1 second), the blowing of air was completed. Then, about 10
The foaming of the slurry continued for a minute. After the raw material slurry was cured to a semi-plastic state, ALC panels were manufactured by a usual method, and the appearance of all the obtained product panels (120 sheets) was visually inspected. We cut parallel to the panel surface in the immediate vicinity of the reinforcing rod mat, and investigated the state of generation of cavities and bubbles on the cut surface. As a result, in visual inspection of the appearance, no giant bubbles or cavities were exposed or cracks were found on the surface or edge of the panel, and no cavities were found in the inspection of the cut surface. It was

[Examples 2 to 4] The surface of the slurry was 30 mm from the upper end 2a of the reinforcing bar mat 10 mm (Example 2).
m (Example 3) and 40 mm (Example 4) when the upper side was reached, except that the valve 15 was opened and air was blown from the nozzle 11 to the surface of the slurry in the mold 1 to make the surface layer of the slurry wavy. Was tested as in Example 1. As a result, the same results as in Example 1 were obtained in any inspection or investigation in any of the Examples.

[Examples 5 and 6] The surface of the slurry was 5 mm (Example 5) and 45 mm from the upper end 2a of the reinforcing bar mat.
mm (Example 6) Same as Example 1 except that the valve 15 was opened and air was blown from the nozzle 11 to the surface of the slurry in the mold 1 to make the surface layer of the slurry wavy when reaching the upper side (mm) (Example 6). Tested. As a result, in the visual inspection of the appearance, the same results as in Example 1 were obtained in all Examples. Further, in the examination of the cut surface, in each of the examples, some cavities were found, but they were not a problem in practical use.

[Prior Art] A test was conducted in the same manner as in Example 1 except that the air blowing device 10 was not used, and air was not blown onto the surface of the slurry to cause the surface layer of the slurry to become wavy. As a result, in visual inspection of appearance, giant bubbles or cavities were exposed on the surface or edge of the panel,
There were 6% of those that needed to be repaired or could not be used due to cracks. Further, in the examination of the cut surface, large and small cavities were concentrated on most of the panels over a width of 10 mm above the upper end of the reinforcing bar mat.

[0016]

As described in detail above, the present invention provides
In the conventional method for producing lightweight cellular concrete,
When the surface of the slurry rises due to foaming and exceeds the upper end portion of the reinforcing bar mat, air is blown onto the surface of the slurry from above the surface of the slurry, and the surface layer of the slurry is waved and stirred, The separation of water in the slurry is prevented, and the expansion of the slurry by the foaming gas is made uniform, so that the slurry is expanded above the horizontal reinforcing bars of the rebar mat, particularly right above the reinforcing bars. In addition, it is possible to easily prevent generation of huge bubbles, cavities, or cracks. As a result, there is no need to expose or crack huge bubbles or cavities on the surface or edge of the product panel, which eliminates the need for product repairs, saves labor, and improves product yield. Further, the air blowing device used in the present invention has a simple structure and is inexpensive, and the existing crane for pin removal can be used as the crane for suspending this device. Further, since the air is blown, the pin bridge suspended on the formwork does not hinder the operation of blowing the air, and a remarkable effect is obtained in practical use.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a part of an ALC manufacturing apparatus of the present invention.

[Explanation of symbols]

 1 Formwork 1a Formwork upper edge 2 Reinforcing bar mat 2a Reinforcing bar mat upper end 3 pins 4 pin bridge 10 Air spraying device 11 Nozzle 12 Table 13 Receiver tank 14 Compressor 15 Valve 16 Crane

Claims (6)

[Claims] 1. A method for producing a lightweight cellular concrete in which a raw material slurry is poured into a mold having a reinforced mat set therein to foam and harden into a semi-plastic state, and then the obtained semi-plastic material is steam-cured in an autoclave. In, when the surface of the raw material slurry rises due to the foaming and exceeds the upper end portion of the rebar mat, air is blown onto the surface of the raw material slurry from above the surface of the raw material slurry to form a surface layer of the raw material slurry. A method for producing a lightweight cellular concrete, which is characterized by oscillating. 2. The method for producing lightweight cellular concrete according to claim 1, wherein the surface layer of the raw material slurry is a layer from the surface of the raw material slurry to the upper end portion of the reinforcing rod mat. 3. The method according to claim 1, wherein when the surface of the raw material slurry exceeds the upper end of the rebar mat, the surface reaches 10 to 40 mm above the upper end of the rebar mat. Manufacturing method of lightweight cellular concrete. 4. The method for producing a lightweight cellular concrete according to claim 1, 2 or 3, wherein the blowing of air is completed before the foaming is completed. 5. Light-weight cellular concrete produced by the method according to claim 1, 2, 3 or 4, which has a large number of giant bubbles or few cavities or cracks. 6. A lightweight cellular concrete manufacturing apparatus having a formwork into which a reinforcing rod mat is set and a raw material slurry is injected, and an autoclave for steam curing a semi-plastic material in which the injected raw material slurry is hardened. A lightweight cellular concrete characterized in that an air blowing device for blowing air to the surface is arranged above the upper edge of the mold so as to be movable parallel to the longitudinal direction of the upper edge of the mold. Manufacturing equipment.