JP2744396B2 - Lightweight cement composition for extrusion molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a cement composition that can provide a cured product having excellent surface smoothness and fire resistance. The cement composition of the present invention is suitable for producing extruded hollow panels and the like for civil engineering.

[0002]

2. Description of the Related Art Extrusion molding of a cement-based matrix is a method that is frequently used, particularly in the production of materials for construction, because of its high productivity and satisfactory quality.

[0003] Among the cement-based matrix formulations, siliceous materials include various materials such as silica powder, silica sand, silica fume, volcanic eruption products, granulated slag, a heating foaming material for volcanic eruption materials, and a material obtained by heating and foaming rock. Is selected according to the purpose.

Particularly in the case of extruded materials, cement,
In addition to the siliceous material, various fibers, fillers, lubricating materials, and thickeners are blended to improve extrudability and shape retention.

The extruders used for extrusion molding are classified into ram type extruders with low productivity, regardless of materials, and screw type extruders with high productivity, the latter being mainly used.

In the screw type extruder, if the material is hard, it is closed at the mold and slips at the auger. On the other hand, a soft material cannot generate a sufficient discharge pressure, and rotates with the auger. And it is difficult to extrude.

[0007] Extruded materials are also impractical for use in manufacturing hollow members if shape retention is poor. Therefore, development of a material that achieves both extrudability and shape retention has been promoted.

Conventionally, cement, siliceous materials, various fibers,
In the case of extrusion molding using a composition containing a filler, a lubricant, a thickener, and the like, for example, Japanese Patent Application Laid-Open No.
As shown in Japanese Patent Publication No. 05, asbestos is indispensable, and asbestos is used in an amount of 2 to 20 parts by weight of the powder.

As is known, asbestos is an excellent material in terms of strength and also as a filler, a lubricating material and a thickening material. I have.

[0010] The extruded plate is formed under a high pressure, so that it is dense and has a smooth surface. On the other hand, it is necessary to use a dense aggregate that can overcome the forming pressure. Therefore, there is a limit even if it is hollow, and the weight of the material itself has been required to be reduced.

Further, a general extruded plate uses only short fibers instead of continuous fibers as fibers, and the fracture state is brittle.
Attempts have been made to reinforce with continuous fibers as seen in JP-A-130418.

Particularly in such a case, since the mold portion becomes complicated and the extrusion pressure increases, it has been extremely difficult to eliminate asbestos, which is also a sliding material, and to reduce the weight.

[0013] Under the above-mentioned background, a light-weight compound in a cement composition is disclosed in JP-A-55-124605.
As a light weight blend containing diatomaceous earth and asbestos and a lightweight asbestos-free blend as shown in JP-A-1-96050, silica fume is used in place of asbestos and pearlite is used as a lightweight aggregate. And the like have been proposed.

However, these compositions contain asbestos as a composition or are simple compositions having a low extrusion pressure, and are lightweight but free of asbestos and capable of withstanding high extrusion molding pressure. Not a practical formulation.

[0015]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a hollow material that is asbestos-free, lightweight, can withstand high extrusion molding pressure, can be extruded, has a high molding speed, and has a hollow ratio of 30% or more. It is intended to provide a practical lightweight cement composition which has a sufficient shape-retaining property, a high strength, and can obtain a cured product excellent in fire resistance.

[0016]

According to the present invention, there is provided a cement containing a matrix and a pulp in an amount of 1 to 3 parts by weight per 100 parts by weight of a powder of a siliceous material. 2 to 200 parts by weight of a volcanic ejecta such as shirasu, white clay, volcanic ash and / or 2 to 50 parts of a lightweight aggregate foamed from the volcanic ejecta as a raw material
Parts by weight, and the lightweight aggregate has an average particle size of 100
A lightweight cement composition for extrusion molding, wherein the composition is not more than μm and the apparent density is not less than 0.9.

The lightweight cement composition for extrusion molding according to the present invention comprises a hollow extruder having a hollow portion having an area of 30% or more of the total area, a continuous reinforcing material inserted therein, and high extrusion molding using a screw type extruder. Its use for extrusion under pressure is suitable for its intended purpose.

The present inventors have conducted basic rheological studies on the compatibility between the above-mentioned shape retention and extrudability required for extrusion molding, and have found that the following two points are important. Based on this, the present invention was completed.

First, in order to enhance the shape retention, the shear strength of the material after kneading the matrix component and water is increased to a certain value or more;

Second, in order to ensure extrudability, a lightweight aggregate in which the internal friction angle of the kneaded material is kept as low as possible and the packing density is hardly changed by the extrusion pressure is used.

That is, in order to increase the shear yield strength to a certain value or more, it is necessary to add a fiber material.

The reason why pulp is used as the fiber material is to obtain an appropriate shear yield strength after kneading. Usually, 1 to 100 parts by weight of the matrix component cement and the siliceous material powder are used. 3 parts by weight are blended.

If the pulp content is less than 1 part by weight, the shape retention is poor due to the low shear yield strength, and if it is more than 3 parts by weight, the pulp may be clogged by a mold and may not satisfy the nonflammability condition. .

Pulp is a material which is alkali-resistant, resistant to heat treatment in an autoclave, economical, easily available, and can contribute to environmental problems by using waste paper pulp.

Further, the siliceous material is a fine aggregate as close as possible to a sphere and as fine as the grain size of cement in order to keep the internal friction angle within a certain range and to withstand high extrusion molding pressure. It is a material whose apparent density (density measured by Beckman hydrometer) that determines the strength is not very small.

Among such materials, a material having high strength, economical, excellent in durability and excellent in fire resistance has been intensively selected. As a result, an average particle diameter of 100 μm or less and an apparent density of 0.9 or more is obtained. We found a combination of volcanic products such as shirasu, clay, volcanic ash, etc., and a lightweight aggregate made by heating and foaming them.

These have an appropriate particle size, a round particle shape, an appropriate apparent density range and the required strength.
This is because it has the required performance.

Moreover, it is economical, rich in fire resistance, has abundant reserves, and is produced in various parts of the country.

Depending on the required strength and specific gravity, these are 2 to 20 volcanic products per 100 parts by weight of cement.
0 parts by weight and 2 to 50 parts by weight of the foamed lightweight aggregate are blended.

Further, both may be used in combination. The upper limit of the blending amount of both is determined by whether extrusion is possible or clogging,
With respect to 100 parts by weight of cement, up to 200 parts by weight can be extruded in the case of a volcanic ejecta and up to 50 parts by weight of a heated foamed lightweight aggregate.

The lower limit of the blending amount of both is determined by the degree of weight reduction required for the cement composition and the fire resistance. If the blending amount of both is less than 2 parts by weight, the weight cannot be reduced,
Also, it has poor fire resistance.

What is important here is the combination of the particle size and the apparent density of the two. A material with a large particle size is lightweight, but has a high internal friction angle, a high extrusion pressure, and is difficult to extrude.

Conversely, a material having a small particle size has a small internal friction angle and is easy to extrude, but is not lightweight.

Further, a material having a large apparent density is not crushed by the extrusion pressure and is easily extruded, but is not suitable for weight reduction. Conversely, a material having a small apparent density is suitable for weight reduction, but is easily crushed by extrusion pressure and is difficult to extrude.

In addition, it has been confirmed by a number of extrusion experiments that the combination of the average particle size and the apparent density is important in order to obtain the required extrusion performance, and the average particle size is 100 μm or less and the apparent density is 0.9 or more. Was found to be a requirement for extrudable materials.

Although the volcanic eruption products vary in particle size and density depending on the place of production and ore vein, they can be used after adjusting to the required particle size and density by classification.

In the case of lightweight aggregates such as pearlite obtained by heating and foaming from rhyolite, perlite and shale, the surface is porous and the shape is not round. The extrudable compounding amount is only 5 parts by weight or less of the total powder amount, which is not suitable for the purpose of reducing the weight of the present invention.

Light aggregates such as pearlite are poor in durability because of their porous nature, resulting in an increase in water absorption and poor freeze-thaw properties.

In particular, the present invention is effective when extruding using a screw type extruder, having a complicated mold for inserting a continuous reinforcing material, and having a hollow ratio of 30% or more of the whole. Therefore, the auger tip discharge pressure is approximately 25kgf /
cm ² or more.

Here, the hollow ratio is the ratio of the cross-sectional area of the hollow portion to the total cross-sectional area when there is no hollow portion, and is shown in FIG.

When the hollow ratio is less than 30%, the resistance is small, the discharge pressure at the tip of the auger is 25 kgf / cm ² or less, and extrusion can be carried out regardless of the material.

As the continuous reinforcing material to be inserted, carbon fiber, carbon fiber reinforced plastic, reinforcing bars, deformed reinforcing bars, stainless steel wires, PC steel wires, and other wire materials, nets, meshes, woven fabrics, and the like are used.

In addition, in addition to the materials described above, the cement composition for extrusion molding contains methyl cellulose as a thickening agent in an amount of 0.5 to 2. Usually, 0 parts by weight is added, and sometimes 0.5 to 10.0 parts by weight of mineral fibers are mixed, but these can be combined as needed.

[0044]

The invention is innovative in that the results of the rheological analysis are particularly linked to practical use. According to this composition, since the material at the time of extrusion has an appropriate internal friction angle and shear strength, it is possible to achieve both extrudability and shape retention.

As a result, using a lightweight cement composition made of asbestos-free, it is possible to extrude withstanding a high extrusion molding pressure, a high molding speed, a sufficient shape retention, a high strength, and a hollow with excellent fire resistance. An extruded material can be obtained.

[0046]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

1) Compounding The total amount of the cement and the siliceous material (silica powder, volcanic eruption material, lightweight aggregate obtained by heating and foaming the volcanic eruption material) is defined as 100 parts by weight. The results are shown in Table 1.

Table 2 shows the breakdown of the powder consisting of cement and siliceous materials (silica powder, volcanic eruption products, and lightweight aggregate obtained by heating and foaming volcanic eruption materials) described in Table 1 as 100 parts by weight. Is given as 100 parts by weight of cement.

Embodiments 1 to 9 are cases in which a volcanic ejecta as a siliceous material and a heated foamed lightweight aggregate are used alone.

Here, in Examples 1 to 4, volcanic ejecta 1
The case of 50 parts by weight is shown, and Examples 5 to 9 show the cases where the heat-foamable lightweight aggregate is 35 to 7 parts by weight.

Examples 10 to 13 are cases in which a volcanic ejecta as a siliceous material and a volcanic ejecta heated foaming lightweight aggregate are used in combination.

Further, as comparative examples, examples using siliceous materials whose grain size and apparent density deviate from the range of the present invention (Comparative Examples 1 to 6), examples using asbestos (Comparative Examples 7 and 8), and volcanoes Comparative Example 9 in which no effusion or volcanic effusion heated foamed lightweight aggregate is used is shown.

2) Evaluation of Extrudability and Shape Retaining Property The above-mentioned composition was kneaded with a mixer and a kneader, a continuous reinforcing bar was inserted, and extruded into a hollow section having a hollow ratio of 40%.

During the extrusion, the extrusion pressure and the extrusion speed at the auger outlet were continuously measured. Also, the shear yield strength of the extruded sample
It was measured with a uniaxial shear tester for soil test (sample diameter 4 cm) .

From the above results, Table 2 shows the extrusion pressure, extrusion speed, and post-extrusion shear yield strength , which are considered to indicate the extrudability, and are considered to indicate the shape retention.

At the same time, the quality of the surface properties was observed during extrusion. Here, the meanings of the symbols shown in the table are as follows.

A: The surface is beautiful and smooth A ': The surface is beautiful but slightly rough B: The surface is rough C: The surface has cracks X: Cannot be extruded (clogged with mold)

3) Measurement of Physical Properties After Curing The sample after extrusion molding was subjected to specific gravity, bending strength and fire resistance test after steam curing and autoclave curing.

The specific gravity was measured in an absolutely dry state, and the bending strength was cut from a hollow section into a plate having a thickness of 12 mm, polished, and cut to a length of 3 mm.
It was measured at a central load of 00 mm.

In the fire resistance test, pass / fail was determined by cracking, explosion, back surface temperature and the like according to JIS-A1304 fire resistance test method for building structural members. Here, the meanings of the symbols shown in the table are as follows.

A: Passed fire test X: Failed fire test

4) Comprehensive Judgment Looking at the above results comprehensively, the bottom row of Table 2 shows the overall judge result. Examples 1 to 13 are formulations that can withstand practical use.

On the other hand, Comparative Example 1 had a low extrusion rate and poor surface properties, Comparative Examples 2 to 6 could not be extruded, Comparative Examples 7 and 8 could not be used because of the asbestos compounded, and Comparative Example 9 was not used. It failed in the fire test and proved to be unsuitable for practical use.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

[Table 5]

[0069]

[Table 6]

[0070]

[Table 7]

[0071]

[Table 8]

[0072]

[Table 9]

[0073]

[Table 10]

[0074]

According to the present invention, it is lightweight, can extrude withstanding high extrusion molding pressure, has a high molding speed, and has a hollow ratio of 3
It is possible to obtain a practical lightweight cement composition made of asbestos, which has sufficient shape retention for hollow materials of 0% or more, high strength, excellent fire resistance, and high-performance extruded building materials.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an extruded plate for showing the definition of the hollow ratio in the present invention.

[Explanation of symbols]

 1 Hollow section cross section 2 Matrix section cross section

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 14:14 14:16) (72) Inventor Tatsuo Suenaga 2-9-1-1, Tobita-Ken, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Inside the research institute (72) Inventor Koji Satoyama 2-9-1, Tobita-Sen, Chofu-shi, Tokyo Kashima Construction Co., Ltd.Technical research institute (56) References JP-A-5-17262 (JP, A) JP-A-4-300229 (JP, A) JP-A-53-34819 (JP, A)

Claims (1)

(57) [Claims] A pulp is used in an amount of 1 to 3 parts per 100 parts by weight of a powder of a cement and a siliceous material as matrix components.
Per 100 parts by weight of cement as a siliceous material, and 2 to 2 volcanic products such as shirasu, clay, volcanic ash, etc.
And 2 to 50 parts by weight of a lightweight aggregate obtained by heating and foaming from 00 parts by weight and / or the volcanic ejecta as a raw material,
The lightweight cement composition for extrusion molding, wherein the lightweight aggregate has an average particle diameter of 100 μm or less and an apparent specific gravity of 0.9 or more.