JP3058627B1 - Portland cement for ALC production and method for producing ALC - Google Patents

Abstract

Kind Code: A1 Since a hemihydrate gypsum having a high solubility at 40 to 50 ° C. is added to a Portland cement clinker in a specific range, the viscosity of the ALC slurry in the initial stage is low, and the same type is used. The difference in the foaming height in the frame is reduced, and the air bubbles are more uniform, which can be expected to prevent the generation of voids around the reinforcing bar, especially above the reinforcing bar. Accordingly, the present invention provides a cement for ALC production and a method for producing the cement for ALC production, which achieves a sufficient hardness at an early stage and has high productivity. In the method for manufacturing A ALC, gypsum Portland cement-based cement to be used, characterized in that 20 to 80 wt% converted to SO ₃ is hemihydrate gypsum. ALC using the obtained cement for ALC production
Is characterized by the following method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a lightweight cellular concrete (hereinafter referred to as "ALC") capable of maintaining a low viscosity until the foaming by the reaction of aluminum powder is completed after injecting a slurry at 40 to 50.degree. )) And a method for producing ALC.

[0002]

2. Description of the Related Art In general, to produce ALC, water is first added to a compounding raw material consisting of a silicic acid raw material powder such as silica stone, a calcareous raw material powder such as quicklime, and Portland cement, and then mixed with aluminum. An ALC slurry is prepared by adding a foaming agent such as powder, and then the slurry is poured into a mold incorporating a reinforcing bar to cause foaming. When a predetermined time has elapsed and the material has become semi-plastic, a piano wire is used. It is manufactured by a method in which the product is cut into a desired size, and then the semi-plastic body is placed in an autoclave and subjected to steam curing at a high temperature and a high pressure to obtain a product.

As a preferable condition in such a production method, an ALC slurry obtained from a compounded raw material for producing ALC has a low viscosity until the foaming is completed after being injected into a mold. The reason is that when the viscosity of the ALC slurry becomes high, the foaming is disturbed, the size of the bubbles becomes uneven, and the distribution becomes uneven. In particular, when the ALC slurry foams in a high-viscosity state, cavities are likely to be generated on the reinforcing reinforcing bar in the upper part in the foaming direction, and when this cavity occurs, the adhesive force between the ALC and the reinforcing reinforcing bar is reduced, and as a building, There is a risk of adversely affecting the strength of the steel.

ALC slurry is generally 6 m in length,
Foaming starts immediately after being cast from a fixed position in a mold having a width of 1.5 m and a height of 0.65 m.
When the viscosity of the C slurry is high, it is not possible to flow so that the foaming height becomes uniform, and there is a difference in height between the vicinity of the slurry casting port and a portion farther from the slurry casting port. In such a portion, there is also a problem that the reinforcing bar is exposed and the dimensions of the product ALC are insufficient.

[0005] As a result of examining the viscosity of the ALC slurry so as not to form a cavity in the upper part of the reinforcing steel bar, for example, a NO. When measured at a rotation speed of 1 rpm using 21 rotors, it was found that the viscosity had to be 100 Pa · sec or less within 30 minutes after casting at which foaming was almost completed. Although various factors can be considered as factors affecting the viscosity of the ALC slurry, it has been found that the properties of Portland cement used as a raw material are the largest, and Portland cement capable of lowering the viscosity of the ALC slurry has been desired.

[0006]

The Portland cement includes 3CaO.Al ₂ O ₃ (usually C ₃
A) (abbreviated as A) rapidly undergoes a hydration reaction upon contact with water, causing stiffness. Gypsum dihydrate is added to ordinary Portland cement clinker to prevent this stiffness and obtain a stable setting time. The dihydrate gypsum is mixed with Portland cement clinker and pulverized by a finishing mill, loses water of crystallization due to heat at the time of pulverization, and partially becomes hemihydrate gypsum.

The SO ₄ ^2- ion eluted from gypsum is C
₃ reacts with _A produces ettringite are mineral slightly soluble in water. The temperature at which cement is normally used, eg 2
At 0 ° C., the hydration of C ₃ A is relatively slow,
By adding gypsum of about 2.0% by weight for ordinary cement and moderately heated Portland cement, about 3.0% by weight for early-strength Portland cement, and about 4.0% by weight for ultra-high-strength Portland cement, C ₃ A is added. The surface can be covered with ettringite, which can delay the setting of the Portland cement clinker.

However, in the production of ALC, in order to improve the productivity, the casting temperature is maintained at a high temperature of 40 to 50 ° C. to accelerate the hydration reaction of Portland cement, and after the ALC slurry is injected into the mold, it hardens. The time to complete is reduced according to the production line. Casting temperature 40-50
When the temperature is increased to ℃, the hydration reaction of C ₃ A becomes more active, but since the solubility of gypsum dihydrate hardly increases even when the temperature is increased, ettringite is formed with respect to the hydration reaction of C ₃ A. The supply of SO ₄ ²⁻ ions to keep up can no longer keep up, and the C ₃ A surface cannot be covered with ettringite. Therefore, the reaction of C ₃ A proceeds more rapidly, and the viscosity of the ALC slurry increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended for ALC production which can maintain a low viscosity until the foaming is completed after the injection of the ALC slurry into the mold without increasing the kneading water. Portland cement and ALC
It is an object of the present invention to provide a production method of

[0010]

The present inventors have conducted various studies on Portland cement for ALC production which can maintain a low viscosity until the foaming is completed after injecting the ALC slurry into a mold. The following portland cement is used as the following, and attention is focused on gypsum added to clinker in the portland cement, and it is found that the above-mentioned problems are solved by specifying the type of gypsum and the amount thereof added, thereby completing the present invention. Reached.

Therefore, in order to achieve the above object, the Portland cement for ALC production according to the first embodiment of the present invention is characterized in that the Portland cement used has a 3CaO.SiO ₂ content Y (% by weight) in the cement. The relationship with the Blaine specific surface area X (cm ² / g) is as follows: X ≦ 4000, 58 ≦ Y ≦ 70 and 94−0.012 · X ≦ Y ≦ 114-0.01
In Portland cement for ALC production, which is a cement satisfying 2 · X (hereinafter referred to as “low brane early strength Portland cement”), among the total gypsum added to the Portland cement used, 20 to _{30 in} terms of SO ₃
80% by weight is gypsum hemihydrate.

An ALC according to a second embodiment of the present invention
Is characterized by using the portland cement for ALC production according to the first embodiment.

[0013] In the present invention, the total gypsum addition amount when the Portland cement used was the low Blaine early strength Portland cement, a specific surface area of 3300 cm ² / g or more when 3.5 wt% or less, a specific surface area of 3300 cm ² / g
If it is less than 3.0% by weight or less.

[0014] Low Blaine early-strength Portland cement for ALC preparation according to the present invention, among the plaster amount to be added to the Portland cement clinker, 20 to 80 wt% converted to SO ₃ is hemihydrate gypsum is necessary.

[0015] By using such Portland cement for producing ALC, it is possible to easily produce ALC which can maintain a low viscosity until the foaming is completed after injecting the ALC slurry into the mold. It became.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized in that, of all the gypsum in the low-brain, early-strength Portland cement used, 20 to 80% by weight in terms of SO ₃ is hemihydrate gypsum. The solubility of hemihydrate gypsum in ALC slurry at 40-50 ° C. is about 3-4 times that of dihydrate gypsum.
Therefore, if a specific amount of hemihydrate gypsum is used, SO ₄ ^2- ions are quickly supplied from the hemihydrate gypsum, the C ₃ A surface is covered with ettringite, stiffening of Portland cement is prevented, and the viscosity of the ALC slurry is reduced. It can be kept low.

[0017] And the proportion of hemihydrate gypsum in the present invention was defined as 20 to 80 wt% converted to SO ₃ is less supply amount of _SO ^{4 2-ions} is less than 20 wt%, delaying the stiffness of Portland cement On the other hand, if the content exceeds 80% by weight, the excess of the hemihydrate gypsum which is not used for the production of ettringite is reprecipitated as gypsum when it is reprecipitated as needle-like crystals. This is because

[0018]

The present invention will be described below with reference to examples and comparative examples. In all Examples and Comparative Examples, 70% by weight of water was added to 55% by weight of silica powder as a siliceous raw material, 10% by weight of quick lime as a calcareous raw material, and 35% by weight of low-brane and early-strength Portland cement, and mixed. Then, an ALC slurry was prepared by adding and mixing 0.07 parts by weight of aluminum powder as a foaming agent. Next, the ALC slurry was cast from one longitudinal end of a mold having a length of 6 m, a width of 1.5 m and a height of 0.65 m.

The raw materials were prepared by changing the ratio of the gypsum hemihydrate added to the low-brane, early-strength Portland cement clinker. These are summarized in Table 1 as Examples and Comparative Examples. Here, the low brane early strength Portland cement falls below the JIS of the early strength Portland cement for fineness less than 3300 cm ² / g,
Here, if the fineness is within the standard value, the term "low brane early strength Portland cement" is used as a trial cement using a cement clinker that satisfies the standard of early strength Portland cement.

[0020] Then, a NO. Using a 21 rotor, the viscosity was measured at a rotation speed of 1 rpm for 30 minutes after casting, at which foaming was almost completed. Further, as shown in FIG. 1, the final foam height on the ALC slurry casting side and the opposite side in the direction of the length of the mold frame of 6 m was measured. Further, as shown in FIG. 2, the obtained ALC panel was cut at an arbitrary position in the longitudinal direction at five locations in a width direction of 60 cm, and the cavities on each reinforcing bar exposed on the cut surface were copied on tracing paper. The area was measured with an image processing device, and the average value was obtained. The results of these measurements are also shown in Table 1.

[0021]

[Table 1]

As can be seen from Table 1, in the embodiment of the present invention,
In each case, the viscosity was reduced to 100 Pa · sec or less as compared with the comparative example using the same type of low brane early strength Portland cement.
Had properties suitable for the production of Regarding the foaming height, the difference between the casting side and the opposite side was smaller in the example of the present invention than in the comparative example in which the same type of Portland cement was used. Further, the area of the cavity above the reinforcing bar was extremely small in the example of the present invention as compared with the comparative example using the same type of Portland cement. That is, it was found that when the low brane early strength Portland cement according to the present invention was used, it was possible to suppress the increase in viscosity during the foaming process of the ALC slurry.

[0023]

As described above, according to the present invention, from 40 to
Since the hemihydrate gypsum having a high solubility at 50 ° C. is added to a low-brain, early-strength Portland cement clinker in a specific range, the viscosity of the ALC slurry at the initial stage is low, and the foaming height in the same mold is low. The difference in height becomes smaller. In addition, the bubbles become uniform, and it can be expected to prevent the generation of voids around the reinforcing bar, especially above the reinforcing bar,
In addition, since the casting temperature can be set to 40 to 50 ° C., the productivity is high because the hardness reaches a sufficient level early,
It is very suitable as Portland cement for ALC production.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state of a final foaming height on a slurry casting side and an opposite side thereof in a mold length direction of 6 m.

FIG. 2 is a schematic diagram schematically showing cavities on each reinforcing bar exposed at a cut surface at five locations at an arbitrary position in the longitudinal direction of the ALC panel in a width direction of 60 cm.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C04B 111: 40 (72) Inventor Shoji Futaki 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Metal Mining Co., Ltd. ( 72) Inventor Tatsuo Isobata 7-55 Minamienkajima, Taisho-ku, Osaka-shi, Osaka Sumitomo Osaka Cement Co., Ltd. Cement Concrete Research Laboratory (56) References JP-A-10-152359 (JP, A) JP JP-A-6-80456 (JP, A) JP-A-5-9045 (JP, A) JP-A-6-206745 (JP, A) JP-A-7-196344 (JP, A) JP-A-3-183646 (JP) JP-A-50-158614 (JP, A) JP-A-2-80355 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 7/02 C04B 28/04 C04B 38/02 C04B 22/14 C04B 22:14 C04B 111: 40

Claims (2)

(57) [Claims] In the Portland cement to be used, the relation between the content Y (% by weight) of 3CaO.SiO _{2 in} the cement and the specific surface area of Blaine X (cm ² / g) is as follows: X ≦ 4000, 58 ≦ Y ≦ 70 and 94−0.012 · X ≦ Y ≦ 114-0.01
In Portland cement for ALC producing a cement that satisfies 2 · X, of the total gypsum to be added to the Portland cement to the use, converted to SO ₃ 20-8
Portland cement for ALC production, wherein 0% by weight is hemihydrate gypsum. 2. A method for producing ALC, comprising using the portland cement for producing ALC according to claim 1.