JPH0822789B2 - Aerated concrete manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention obtains a lightweight cellular concrete excellent in physical properties such as strength, dimensional stability and water absorption by incorporating an inorganic foam having low water absorption. Manufacturing method for.

[Prior Art] A hardened body in which a large amount of bubbles are introduced into concrete, that is, aerated concrete has a larger drying shrinkage and a lower strength than general concrete. In particular, such a lack of performance is remarkable in the case of aerated concrete that is subjected to normal pressure steam curing, wet curing and air curing other than high temperature and high pressure steam curing.

Conventionally, ultra-light aggregate (hereinafter referred to as pearlite), shale, which is obtained by firing and expanding glassy volcanic rocks such as obsidian, pine rock, pearlite, trachyte to improve physical properties such as dry shrinkage and strength of cellular concrete. A method of using an aggregate such as an artificial lightweight aggregate obtained by firing and expanding clay or the like, a natural lightweight aggregate, or an ordinary aggregate is used. However, since perlite generally has a high water absorption rate and it is difficult to reduce the total amount of water in mortar and concrete, the strength, drying shrinkage, water absorption and the like of aerated concrete are not improved so much. This tendency is remarkable especially in the pine rocks, pearlites, and trachyte pearlites other than obsidian pearlites, because of their high water absorption. In the case of obsidian perlite, the water absorption of the aggregate is relatively small and the drying shrinkage and water absorption of concrete are smaller than those of other perlites, but the concrete strength is not so improved. It is considered that this is because the obsidian pearlite has a spherical shape and a smooth surface state, so that the adhesion to the cement is not good, and that the aggregate contains fragile particles that can be easily crushed by hand.

It is effective to use a surfactant such as a high-performance water-reducing agent to reduce the amount of water mixed with concrete to improve the strength and drying shrinkage. The influence of abrupt water absorption of pearlite during and immediately after kneading is large, which may cause remarkable decrease in fluidity and stiffness. Further, the use of a large amount of water reducing agent not only hinders the hydration reaction of cement, but also causes problems such as defoaming of bubbles entrained in concrete and coarsening due to a decrease in viscosity of cement slurry.

Since the artificial lightweight aggregate or the ordinary aggregate has a low water absorption rate of the aggregate and a good adhesive property with cement, it has excellent physical properties such as strength and drying shrinkage when properly mixed. However, due to the high specific gravity of the aggregate, in order to achieve a high degree of weight saving of concrete, it is inevitable that a large amount of air bubbles are introduced into the cement hardened body to reduce the weight. Technical problems arise. That is, the introduced bubbles are coarsened or easily defoamed, and it is difficult to introduce uniform and fine bubbles, so that the strength and water absorption of concrete are lowered.

[Problems to be Solved by the Invention] The object of the present invention is to eliminate the drawbacks of conventional cellular concrete using lightweight aggregates such as the above-mentioned pearlite, and to provide bubbles having excellent physical properties such as strength, drying shrinkage, and water absorption. It is intended to provide a method for manufacturing concrete.

[Means for Solving the Problems] The present invention provides an inorganic foam in which a unit volume weight of 0.1 to 0.6 kg / 100 parts by volume of aerated concrete is generated by heating and foaming an amorphous residue generated during a quartz gasification reaction. The present invention relates to a method for producing cellular concrete, which comprises mixing 20 to 90 parts by volume of inorganic foam.
That is, the present invention, water, cement unit volume weight 0.1 ~
Mix 0.6 kg / inorganic foam, add a water reducing agent, etc. if necessary, and knead, foam, etc. to obtain 20% of unit volume weight 0.1-0.6 kg / in 100% by volume of cellular concrete. The present invention relates to a method for producing aerated concrete mixed with 90 parts by volume.

The inorganic foam used in the present invention is obtained by heating and foaming the amorphous residue generated during the quartz gasification reaction.
Examples of such an inorganic foam include, for example, JP-A-61-119.
The inorganic foam proposed in 7479 is suitable, which is a residue generated when partially oxidizing quartz at a temperature below the softening degree of coal in a quartz gasifier such as Texaco method, generally 1300 to 1500 ° C. Is produced by heating and foaming at a temperature of 600 ° C. or higher.

The amount of use of the inorganic foam is 20 to 90 parts by volume in bulk volume per 100 parts by volume of cellular concrete, preferably 30 to
It is 85 parts by volume. If it is less than 20 parts by volume, the effect of improving the physical properties of the hardened concrete will not be sufficiently exhibited. If it is more than 90 parts by volume, the fluidity of aerated concrete when kneading and the fluidity of kneaded concrete will deteriorate, and
It causes problems in surface finishing.

Inorganic foam used in the production method of the present invention, JIS A50
The unit volume weight measured by the method of 07-1977 "Perlite" is usually 0.1 to 0.6 kg /, preferably 0.2 to
It is 0.5 kg /. When the unit volume weight is less than 0.1 kg /, the water absorption rate becomes high, the mixing water amount of concrete increases, and the strength of the aggregate itself becomes low, so that the physical properties of the hardened concrete cannot be improved. Unit volume weight is 0.
If it is larger than 6 kg /, the amount of bubbles to be introduced must be increased in order to obtain a cured product having a low specific gravity, which causes coarsening and defoaming of the bubbles, deteriorating the stability of the bubbles and the uniformity of the bubble distribution. Physical properties of hardened concrete deteriorate.

The water absorption rate of the inorganic foam defined in JISA1134-1976 "Test method for specific gravity and water absorption of lightweight structural aggregates" or JIS A1135-1976 "Test method for specific gravity and water absorption of lightweight coarse structural aggregates" is 30 % Or less, preferably 20% or less.

The particle size of the inorganic foam is not particularly limited, but the particle size is 20 mm or less, preferably 10 mm or less.

Introducing air bubbles into concrete is for normal concrete
AE agent, AE water reducing agent other foaming agent or foaming agent,
The introduction method may be a preform method, an afterform method or a mixed foam method.

Examples of hydraulic cement of cellular concrete include Portland cement, alumina cement, blast furnace cement, fly ash cement and silica cement. In addition, reinforcing materials and extenders used to increase the strength of hardened concrete and for increasing the amount, such as fly ash, silica, slag fine powder, high-fine cement, silica powder, and various fibers are used in the production of aerated concrete. You can do it. You can also use expansive material for concrete.

In the present invention, in order to further improve the fluidity of the aerated concrete, and further improve the physical properties of the cured product by further reducing the amount of water used per product unit amount during production, a high-performance water reducing agent, an AE water reducing agent , Water-reducing agents such as water-reducing agents for cement to 0.005 ~
It is preferable to use 5% by weight. The amount of surfactant is 0.
If it is less than 005% by weight, the water reducing effect can hardly be expected.
On the other hand, if it exceeds 5% by weight, problems occur in the hydration reaction of cement and the stability of introduced bubbles as described above.

[Function] Although the cause of improvement of physical properties such as strength, drying shrinkage, and water absorption of the cellular concrete by using the inorganic foam is not clear, the pore structure of the inorganic foam is a fine closed cell structure, and It is considered that the water absorption of the aggregate is small and the strength of the aggregate is high because the shell of the internal bubbles is robust.

The surface of the inorganic foam has a glassy appearance,
Since there are many fine recesses, the adhesion between the surface and the hardened cement is good, and it is presumed that this leads to an improvement in the strength of cellular concrete by the production method of the present invention.

 Hereinafter, the present invention will be described with reference to examples.

[Example] Example 1 According to the compounding conditions of Example 1 in Table 1, water, cement,
After kneading the inorganic foam and the water reducing agent with a Hobart mixer to form a slurry, the kneaded unit volume weight is 1.0 kg /
So that the foaming agent was foamed by a foaming machine, the foaming agent was added and further mixed. The flow rate of aerated concrete measured by the method described in JIS R5201-1987 "Cement physical test method" was adjusted to 210 ± 20 mm by adjusting the amount of the water reducing agent.

After demolding the concrete specimen of 4 × 4 × 16 cm,
Curing was carried out in standard water at 20 ° C for 28 days, and the volumetric water absorption during this period was measured. Further, the compressive strength, flexural strength (JISR5201-1987), drying shrinkage, etc. of the cured product after curing in standard water at 20 ° C for 28 days were determined.

The measurement of the dry shrinkage was carried out by the contact gauge method using the specimen after steam curing (holding at 65 ° C. for 5 hours). One week after steam curing, the specimen was placed in 3 cm below the surface of the water.
It was immersed for a day and then left in a constant temperature and humidity of 20 ° C-RH60%.

 Table 1 shows the physical property values obtained by the experiment.

Part 2 details the materials used to make cellular concrete
Shown in the table.

Examples 2 to 4 Experiments were performed in the same manner as in Example 1 except that the water cement ratio and the water reducing agent amount were changed.

 The compounding conditions and the physical property values are shown in Table 1.

Examples 5 and 6 Experiments were conducted in the same manner as in Example 1 except that the water cement ratio was kept substantially constant at 45 to 48% and the aggregate cement volume ratio was changed.

 The compounding conditions and the physical property values are shown in Table 1.

Example 7 An experiment was conducted in the same manner as in Example 1 except that the unit volume weight of the inorganic foam was 0.22 kg /.

 The compounding conditions and the physical property values are shown in Table 1.

Example 8 An experiment was conducted in the same manner as in Example 1 except that an inorganic foam having a unit volume weight of 0.50 kg / was used.

 The compounding conditions and the physical property values are shown in Table 1.

Comparative Examples 1 to 4 Experiments were performed in the same manner as in Examples 1 to 4 except that obsidian pearlite was used as the aggregate.

 The compounding conditions and the physical property values are shown in Table 1.

Comparative Examples 5 to 7 Experiments were performed in the same manner as in Examples 2 to 4 except that trachylite was used as the aggregate.

 The compounding conditions and the physical property values are shown in Table 1.

Comparative Example 8 An experiment was conducted in the same manner as in Example 1 except that the water cement ratio was 48% and no aggregate was used.

 The compounding conditions and the physical property values are shown in Table 1.

Comparative Examples 9 and 10 Experiments were performed in the same manner as in Examples 5 and 6 except that obsidian perlite was used as the aggregate.

 The compounding conditions and the physical property values are shown in Table 1.

Comparative Example 11 An experiment was conducted in the same manner as in Example 5 except that trachylite was used as the aggregate.

It should be noted that the required flow value could not be obtained when the aggregate cement volume ratio was set to 2.5 using trachylite pearlite.

 The compounding conditions and the physical property values are shown in Table 1.

FIG. 1 shows the results of compressive strength tests of Examples 1 to 4 and Comparative Examples 1 to 8 in terms of the relationship between water cement ratio and strength. Aerated concrete with inorganic foam is more than 30% more than with other aggregates or less than without aggregates
85% high strength was obtained.

FIG. 2 shows the time-dependent changes in the drying shrinkage rate in Example 2 and Comparative Examples 2, 5, and 8. Even under the same blending conditions, cellular concrete using an inorganic foam has a smaller drying shrinkage rate than others.

FIG. 3 shows changes with time in the volumetric water absorption in Example 2 and Comparative Examples 2, 5, and 8. Aerated concrete using an inorganic foam tends to have a smaller water absorption rate than others.

FIG. 4 shows Examples 2, 5, 6 and Comparative Examples 2, 5, 8,
The results of the strength tests of 9, 10, and 11 are shown by the relationship between the aggregate cement volume ratio and the strength.

EFFECTS OF THE INVENTION The present invention overcomes the disadvantages of conventional cellular concrete or cellular concrete using aggregate such as perlite, and obtains lightweight cellular concrete excellent in physical properties such as strength, dimensional stability, and water absorption. To be

[Brief description of drawings]

FIG. 1 shows the relationship between water cement ratio and compressive strength in Examples 1 to 4 and Comparative Examples 1 to 8. FIG. 2 shows Example 2,
The time-dependent change of the dry shrinkage rate in Comparative Examples 2, 5, and 8 is shown. FIG. 3 shows changes with time in the volumetric water absorption in Example 2 and Comparative Examples 2, 5, and 8. FIG. 4 shows the relationship between the aggregate cement volume ratio and the compressive strength in Examples 2, 5, 6 and Comparative Examples 2, 5, 8, 9, 10, 11.

Claims (2)

[Claims] 1. An inorganic foam having a unit volume weight of 0.1 to 0.6 kg / 100 parts by volume of aerated concrete, which is obtained by heating and foaming an amorphous residue generated during a quartz gasification reaction is mixed in at 20 to 90 parts by volume. A method for producing aerated concrete, which is characterized in that 2. The method for producing aerated concrete according to claim 1, wherein 0.005 to 5% by weight of the cement water reducing agent is used with respect to the cement.