JP2736206B2 - Extrusion molding method for cement-based building materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extruding a cement-based building material.

[0002]

2. Description of the Related Art Conventionally, building materials made of fiber-reinforced cement have been very widely manufactured and used. This fiber-reinforced cement building material has many advantages such as the same quality in terms of strength, shape, etc., which can be mass-produced and provided at low cost, and since it does not use natural resources such as wood at all, it is preferable from the viewpoint of resource protection. . An extrusion molding method is also known as a method for producing a fiber-reinforced cement building material. Water is added to the above-mentioned cement compounding material to form a slurry of about 20%, and the kneaded material is shaped into a product.

[0003] By the way, asbestos has been traditionally used as a reinforcing fiber for the above fiber-reinforced cement building materials. However, asbestos is strongly required to be restricted or completely abolished because it causes pollution. Are being sought. Various alternatives such as pulp fiber and synthetic fiber have been tried as alternative fibers, but all of them have water retention, heat resistance, chemical resistance,
Adhesion to the cement matrix, and in extrusion molding, there are advantages and disadvantages in the provision of extrusion performance and the like, and properties comparable to asbestos fibers have not yet been obtained.

Therefore, attention has been focused on increasing the bonding strength of the cement matrix and improving the strength of the entire building material in cooperation with the reinforcing fiber to be added. For example, the amount of added water is reduced and the matrix is reduced by using a water reducing agent in combination. It has been proposed to increase the density of the product, to use fine silica sand such as silica fume having a fine particle size, and to improve the product strength by the combination of the two (for example, JP-A-2-289456, No. 2-307852). For the purpose of improving the extrudability of an asbestos-free compound, addition of magnesium hydroxide to a cement compound (for example, Japanese Patent Application No. 62-253)
No. 204), and addition of a salt of a highly condensed naphthalenesulfonic acid / formalin (eg, Japanese Patent Application No. 3-319882) has been proposed.

[0005]

Problems with the prior art However, although the product strength has been considerably improved by the cooperation with the improvement of the bonding strength between the reinforcing fibers other than asbestos and the cement matrix,
Since the product is in a densely packed state, the specific gravity is high, and there is a problem that the product is necessarily heavy. Particularly in the case of extrusion molding, this problem is remarkable because the material is compressed at the molding die.

In order to reduce the extrusion resistance in extrusion molding, it is necessary to increase the water content of the kneaded product to 20% or more to impart fluidity. Tends to decrease, the specific gravity decreases and the strength decreases.On the other hand, the amount of water added to increase the strength,
For example, when it is reduced to about 18%, the fluidity of the kneaded material is reduced, and the extrusion molding itself becomes difficult, and the surface of the extruded product is roughened to deteriorate the surface condition. In order to solve this, a water reducing agent may be used to improve workability.However, in such a case, the kneaded material is strongly compressed at the forming die portion, and the structure is combined with a small amount of added water. There is a problem that densification tends to occur and disadvantages such as an increase in product specific gravity and a decrease in workability are further promoted.

[0007] On the other hand, the addition of the above-mentioned naphthalenesulfonic acid / formalin high condensate salt has the effect of improving the strength without increasing the specific gravity of the product while maintaining the slurry concentration suitable for extrusion molding. When magnesium hydroxide is added, the lubricity of the slurry is improved, but the former naphthalenesulfonic acid / formalin high condensate salt is relatively expensive and has a problem that is reflected in the product cost.
The latter magnesium hydroxide has a disadvantage that it is difficult to reduce the amount of water used, and the strength of the product is not sufficient.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention maintains a slurry concentration capable of sufficiently maintaining extrusion performance without reducing the amount of water used, based on the prior art, and has a specific gravity of the product. The object of the present invention is to provide an improved method for extruding a cement-based building material that can improve the strength without increasing the temperature.

[0009]

That is, the present invention provides a method for extruding a cement-based building material, comprising: cement, 0.7 to 1.3 times the amount of silica powder and a necessary amount of reinforcing fiber;
In an extrusion molding method for a cement-based building material obtained by adding an extrusion aid to a cement mixture composed of a lightweight aggregate or the like, 0.1 to 3% by weight of naphthalenesulfonic acid. Formalin polycondensate salt and 3 ~ 15
% Of magnesium hydroxide, and further, water is added and mixed to form a kneaded product, and the kneaded product is extruded.

[0010]

The compounding raw materials of the cement compound which is the object of the present invention are the same as those conventionally used, for example, 35 to 65% by weight of cement, 35 to 65% by weight of silica sand, reinforcing fibers 1 to 3 of pulp and the like. For a 100% by weight blending system consisting of 7% by weight,
If necessary, add 0.5 to 20% by weight (5 to 50% by volume) of lightweight aggregates such as pearlite, expanded styrene particles, etc. 0
Those added with 20% by weight are used. Further, the amount of water to be added is about 20 to 55% by weight in the same manner as before, and methylcellulose or the like is used as an extrusion aid.

In the present invention, when water is added to and kneaded with the cement composition, the cement composition is converted to a solid content.
0.1 to 3% by weight of naphthalenesulfonic acid / formalin high condensate salt and 3 to 15% by weight of magnesium hydroxide are added. This naphthalene sulfonic acid / formalin high condensate salt acts as a surfactant, enhances the uniform dispersibility of the cement particles and the silica component particles, and cooperates with magnesium hydroxide described later to remove the obtained cement kneaded product. Increases viscosity and imparts product surface smoothness.

As a result, even if the silica particles are slightly large, the dispersibility with the cement particles is improved, and the particles that are agglomerated with the powder are also dispersed, and the reaction rate is high and the bonding strength of the matrix is high. A good product is obtained. The above naphthalenesulfonic acid / formalin polycondensate salt is known as a water reducing agent, but its use is conventionally to impart fluidity to the slurry when the amount of added water is reduced.
The present invention differs from the conventional method in that the purpose of the present invention is to increase the viscosity without reducing the amount of water added and to uniformly mix the slurry.

The addition amount of 0.1 to 3% by weight in terms of the solid content of the cement mixture is 0.1% by weight due to the critical effect found by the experiment of the present inventors in cooperation with magnesium hydroxide. %, The effect of addition cannot be obtained, and if it is more than 3% by weight, it is wasteful in combination with magnesium hydroxide.

Magnesium hydroxide is added to improve the flowability of the extruded material in cooperation with the salt of a naphthalenesulfonic acid / formalin polycondensate due to its lubricity. If it is less than 3% by weight, the viscosity of the cement kneaded material is
This is because there is no effect of improving lubricity and strength, and if it exceeds 15% by weight, the effect of addition cannot be obtained, and there is a possibility that the strength of the product may be adversely affected.

Thus, a cement kneaded product having sufficiently improved viscosity, fluidity and strength can be obtained by the cooperation of the salt of a highly condensed naphthalenesulfonic acid / formalin and magnesium hydroxide. As a result, the amount of use can be reduced by about 20% as compared with the case where only the naphthalenesulfonic acid / formalin high condensate salt is added, and the effect is superior to the case where only the naphthalenesulfonic acid / formalin high condensate salt is added. Is obtained.

[0016]

Next, an embodiment of the present invention will be described. First, as a cement compound, cement 40% by weight, Blaine value 3500
As a basic composition, 0.85% by weight of expanded styrene expanded beads, 0.6% by weight of methylcellulose (MC) and 50% by weight of water are added to 100% by weight of 53% by weight of silica sand of 7 cm ² / g and 7% by weight of pulp fiber. Prepared.

[Examples 1 and 2] Naphthalenesulfonic acid / formalin highly condensed salt (manufactured by Kao Corporation: trade name "Mighty 150") and magnesium hydroxide were added to the kneaded product having the above basic composition as the composition shown in Table 1. Then, this cement kneaded material was extruded to a thickness of 11 mm, a width of 105 mm, and a length of 200 m.
m at 30 ° C for 15 hours and then pressure 6.7k
Autoclave curing was performed for 8 hours under the condition of g / cm ² . In addition, the surface condition of the extruded product and the bending strength of the curing-hardening test plate were measured during the extrusion molding, and the results are shown in the lower column of Table 1.

Example 3 Naphthalenesulfonic acid / formalin polycondensate (manufactured by Kao Corporation: trade name "Mighty 150") and magnesium hydroxide were added in advance to the water in the above basic composition as the composition shown in Table 1. After stirring well,
This water was added to the above other basic composition to obtain a cement kneaded material, which was extruded to a thickness of 11 mm, a width of 105 mm, and a length of 200 mm.
After a temporary curing at 30 ° C for 15 hours, a pressure of 6.7 kg /
Autoclave curing was performed for 8 hours under the condition of cm ² . In addition, the surface condition of the extruded product and the bending strength of the curing-hardening test plate were measured during the extrusion molding, and the results are shown in the lower column of Table 1.

[Comparative Examples 1 to 3] As shown in Table 1, naphthalenesulfonic acid / formalin high condensate salt and magnesium hydroxide were not added at all, or only one of them was added, and A test plate was formed. When the extrusion performance, the surface condition of the extruded product, and the bending strength of the cured test plate were measured during the extrusion molding, the results in the lower column of Table 1 were obtained.

[0020]

[Table 1]

In Table 1, naphthalenesulfonic acid.
The addition amounts of formalin high-condensate salt (NSF high-condensate salt) and magnesium hydroxide are shown in percent by weight, and ◎ to の in the column of “surface condition” in the test results are based on the following. ◎… The smoothness of the surface is remarkable, and no nests or cracks are observed. △… A plate with a certain width and thickness is formed.
Small nests and cracks are scattered, and surface irregularities are seen. The primary curing strength and the autoclave strength indicate the bending strength after each curing, and the unit of the number is kg / cm ² .

As is evident from Table 1, the Example in which both the naphthalenesulfonic acid / formalin high-condensate salt and magnesium hydroxide were used in combination was the Comparative Example 2 in which a large amount of naphthalenesulfonic acid / formalin high-condensate salt was added. It was found that the same physical property effect as that of Example 1 was obtained, and the effect of excellent physical property was obtained with respect to the other comparative examples.

[0023]

As described above, according to the method of the present invention, the synergistic effect of the naphthalenesulfonic acid / formalin high-condensate salt and magnesium hydroxide is exerted together, and the extrudability and strength of the extruded product are exhibited. Etc. can be improved,
It is possible to manufacture products at low cost.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 24:38 24:22 22:06 16:08 14:16)

Claims (1)

(57) [Claims] Claims: 1. A cement and a cement,
In a method for extruding a cement-based building material obtained by adding an extrusion aid to a cement compound comprising 1.3 times the amount of silica powder and a necessary amount of reinforcing fiber, lightweight aggregate, etc., 0.1 to 3 in terms of solid content of the compound. 1% by weight of a naphthalenesulfonic acid / formalin high-condensate salt and 3% to 15% by weight of magnesium hydroxide, and further added and mixed with water to form a kneaded product. Extrusion molding method for building materials.