JPH08333152A - Cement composition and auxiliary for its extrusion molding - Google Patents

Abstract

PURPOSE: To obtain a molded product improved in mechanical strength, surface smoothness and economy without the need of using asbestos fibers, by using a composition comprising cement, a fine aggregate and fibrillated cellulose of specific size produced by fusion crushing method. CONSTITUTION: This cement composition is obtained by incorporating a mixture of 100 pts.wt. of cement and 50-150 pts.wt. of fine aggregate with 2-10 pts.wt. of fibrillated cellulose 0.01-1μm in single fiber diameter and 1-5mm in single fiber length among such fibers dispersed as an aqueous dispersion of fibers or dehydrated cake (dried product) made from the dispersion produced by disassembling a 1-10wt.% aqueous dispersion of pulp with a fusion crusher, and according as necessary, an additive for physical property modification, etc. This cement composition is then incorporated with 10-70wt.%, based on the whole solid content of the cement composition, of water followed by conducting a kneading. The kneaded product is then subjected to extrusion molding to a desired shape, and the resultant molded product is put to underwater curing, air-curing or high-temperature-high-pressure curing and then dried.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to cement compositions, especially
The present invention relates to a cement composition suitable for extrusion molding.

[0002]

2. Description of the Related Art Cement compositions for extrusion molding used in the field of civil engineering and construction such as exterior wall materials for construction and soundproof walls generally contain mainly cement, fine aggregate, reinforcing fibers and molding aids. I'm out.

Cement compositions of this type usually use asbestos fibers as reinforcing fibers. However, as the harmfulness of asbestos fibers has recently been pointed out, there is an increasing need to refrain from using them. Therefore, studies on alternatives to the asbestos fibers are under way, and, for example, economically advantageous synthetic fibers and cellulose fibers having good hydrophilicity have been put to practical use.

[0004]

Since the synthetic fiber has hydrophobicity, it is difficult to uniformly disperse it in the cement composition.
For this reason, an extrusion-molded article made of a cement composition containing synthetic fibers often lacks strength, and often has poor surface smoothness after curing of the molded article.

On the other hand, an extrusion molded article made of a cement composition containing cellulose fibers often has insufficient mechanical strength. In addition, this composition requires an expensive extrusion aid such as methylcellulose (usually about 2 to 5 parts by weight with respect to 100 parts by weight of cement), and therefore improvement is required from the economical aspect as well. .

An object of the present invention is to inexpensively realize a cement extrusion molded article having high strength and good surface smoothness without using asbestos fibers.

[0007]

Means for Solving the Problems The present inventors have paid attention to the fact that cellulose fibers having good hydrophilicity are effective as reinforcing fibers in place of asbestos fibers, and have made various studies. As a result, the cellulose composition fiberized by the crushing method, in particular, the cement composition obtained by mixing the cellulose having a diameter of 0.01 to 1 μm and a length of 1 to 5 mm has good extrusion moldability. The present inventors have completed the present invention by finding that the obtained extrusion-molded article has high mechanical strength and that the above-mentioned cellulose functions as a substitute for the extrusion aid.

That is, the cement composition according to the present invention comprises 100 parts by weight of cement, 50 to 150 parts by weight of fine aggregate, a diameter of 0.01 to 1 μm obtained by a crushing method,
It contains 2 to 10 parts by weight of fibrous cellulose having a length of 1 to 5 mm. As the fibrous cellulose, an aqueous dispersion containing the same or a dehydrated cake thereof is usually used.

Further, the auxiliary agent for extrusion molding of the cement composition according to the present invention has a diameter of 0.01 to, obtained by a crushing method.
It contains 1 μm and 1-5 mm long fibrous cellulose.

Hereinafter, the present invention will be described in detail.

The cement used in the present invention is not particularly limited as long as it is a commonly used cement. Specifically, various cements such as Portland cement, magnesia cement, alumina cement, mixed cement, and natural cement can be used.

The fine aggregate used in the present invention is not particularly limited as long as it is usually mixed with cement. Specific examples of the fine aggregate include river sand, mountain sand, and broken sand.

The fibrous cellulose used in the present invention is
It is obtained by the crushing method. The fibrous cellulose obtained by the crushing method includes, for example, a cellulose raw material such as wood pulp such as spruce, poplar and beech, linter pulp such as cotton, and non-wood pulp such as kenaf.
A 10% by weight aqueous dispersion is prepared, which is then crushed (for example,
An aqueous dispersion of fibers obtained by defibration using "Supermass Colloider" manufactured by Masuyuki Sangyo Co., Ltd., a dehydrated cake thereof, or a dried product of the dehydrated cake. Since such fibrous cellulose becomes expensive when taken out as a dried product, it is preferable to use an aqueous dispersion or dehydrated cake.

In the present invention, among the above-mentioned fibrous cellulose, the diameter is 0.01 to 1 μm and the length is 1 to 5 mm.
What is used. If the diameter is less than 0.01 μm,
Its manufacture is practically difficult. On the other hand, when the diameter exceeds 1 μm, the effect as a reinforcing fiber becomes poor. Further, when the length is less than 1 mm, it is difficult to obtain a cement molded product having sufficient strength. Conversely, if the length exceeds 5 mm, it will be difficult to manufacture from natural fibers.

The cement composition of the present invention contains 50 to 150 parts by weight and 2 to 50 parts by weight of the above-mentioned fine aggregate and the above-mentioned fibrous cellulose with respect to 100 parts by weight of the above-mentioned cement, respectively.
Contains 10 parts by weight. The content of fibrous cellulose is a value in terms of solid content. When the content of the fine aggregate is less than 50 parts by weight, the strength of the molded product becomes weak. Conversely, 1
If the amount exceeds 50 parts by weight, the molded product may become brittle. On the other hand, when the content of fibrous cellulose is less than 2 parts by weight, a cement extrusion molded article having sufficient strength cannot be obtained. In addition, the surface smoothness of the extruded product may be insufficient. On the other hand, if it exceeds 10 parts by weight, it is economically disadvantageous in practice.

The cement composition of the present invention may contain, in addition to the above-mentioned various essential components, various additives, if necessary, in order to achieve various purposes such as improving the physical properties of the cement molded product. . Examples of the additive include perlite, shirasu balloon, silica flower, vermiculite, chaff powder and the like. Also, methyl cellulose, ethyl cellulose, carboxymethyl cellulose,
An extrusion aid such as hydroxymethyl cellulose may be included.

The cement composition of the present invention is obtained by mixing the cement and the fine aggregate using a mixer such as a Henschel mixer, transferring them to a kneader, and adding the above-mentioned fibrous cellulose and a necessary amount of water to kneading. To be The amount of water added here varies depending on the form of fibrous cellulose, that is, which form of the aqueous dispersion, dehydrated cake, or dried product thereof is used. It is preferably 10 to 70% by weight with respect to the minutes. The amount of water here is a value which also includes the amount of water contained in the fibrous cellulose when the fibrous cellulose in the form of an aqueous dispersion or dehydrated cake is used.

If the amount of water added is less than 10% by weight, the viscosity of the cement composition will be too high.
Smooth extrusion molding becomes difficult. On the other hand, if it exceeds 70% by weight, the composition becomes too soft, and the shape retention of the molded product during extrusion is deteriorated.

In the case of producing an extrusion molded article from the cement composition thus prepared, for example, the cement composition is extruded into a desired shape by using a screw type extruder and then cured in water, Dry in air or after high temperature and high pressure.

The extruded product of the cement composition of the present invention thus obtained has a three-dimensionally complicated distribution of fibrous cellulose and fine aggregate (usually having a particle size of several hundred μm).
(m to several mm) and the fibrous cellulose are sufficiently entangled with each other, so that the strength is higher than that of a molded article made of a composition using conventional ordinary cellulose fibers as reinforcing fibers.

Further, the fibrous cellulose contained in the cement composition has a paste-like form when it comes into contact with water due to its fineness, and therefore it is similar to the aqueous solution or dispersion of the extrusion aid contained in the conventional composition. To enhance the surface smoothness of the molded product. Therefore, according to the cement composition of the present invention, an extrusion molded article having good surface smoothness can be realized at low cost without using an expensive extrusion aid such as methylcellulose.

The extrusion molding aid of the cement composition according to the present invention has a diameter of 0.01 to 1 μm obtained by a crushing method.
m and a length of 1 to 5 mm, which is the same as the fibrous cellulose contained in the above-described cement composition according to the present invention. The auxiliary agent of the present invention composed of such fibrous cellulose is used in various forms such as an aqueous dispersion, a dehydrated cake thereof or a dried product thereof. However, since such fibrous cellulose becomes expensive when made into a dried product, it is usually preferable to use an aqueous dispersion or a dehydrated cake thereof.

Such an auxiliary agent for extrusion molding of the cement composition according to the present invention is a cement composition which has been conventionally used in place of a conventional extrusion auxiliary agent such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose or hydroxymethyl cellulose. Is added to the product. The auxiliary agent of the present invention added to the cement composition exhibits a paste-like form when it comes into contact with water as described above, and exhibits the same action as a conventional extrusion auxiliary agent, and can enhance the surface smoothness of an extrusion molded article. . The extrusion molding aid of the present invention can be provided at a lower cost than conventional extrusion molding aids.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Production Example 1 5 kg of wood pulp cut into 5 cm or less and 95 kg of water were put into a 200 liter container and mixed to prepare a dispersion liquid. This dispersion is a crusher manufactured by Masuyuki Sangyo Co.
It was fed into Supermass Colloider 10-15J "using a metering pump at a speed of 100 kg / hour. The dispersion thus obtained was treated by repeating the same operation three times, and the diameter was 0.3 μm and the length was 0.3 μm. To obtain a fiberized cellulose aqueous dispersion having a fiber diameter of 3 mm.

Production Example 2 The aqueous dispersion of fibrous cellulose obtained in Production Example 1 was compression-filtered using a filter press to obtain 100 parts by weight of fibrous cellulose (solid content) and 200 parts by weight of water. A dehydrated cake of fibrous cellulose was obtained.

Example 1 100 kg of Portland cement and 80 kg of river sand as fine aggregate were thoroughly mixed using a Henschel mixer and charged into a kneader. To this, 15 kg of dehydrated cake of fibrous cellulose obtained in Production Example 2 and 45.5 k of water
and g were added and mixed to obtain a kneaded cement composition.

Next, this kneaded cement composition was used for 23 by using an extruder "DE-50 type" manufactured by Honda Iron Works Co., Ltd.
Extruded at a pressure of kgf / cm ² with a cross section of 12 × 6
A 0 mm plate-shaped cement molded product was obtained.

Example 2 100 kg of Portland cement and 60 kg of river sand as fine aggregate were thoroughly mixed using a Henschel mixer and charged into a kneader. To this, 30 kg (solid content = 5% by weight) of the fibrous cellulose aqueous dispersion obtained in Production Example 1 and 10 kg of water were added and mixed to obtain a kneading cement composition. From this composition, a plate-like cement molded product was obtained in the same manner as in Example 1.

Example 3 100 kg of Portland cement and 60 kg of river sand as fine aggregate were mixed in the same manner as in Example 2 except that 5 kg of rice husk powder was further added when mixing with a Henschel mixer. A cement molded product was obtained.

Example 4 Similar to Example 2 except that 100 kg of Portland cement and 60 kg of river sand as fine aggregate were mixed with a Henschel mixer, and 2 kg of methylcellulose as an extrusion aid was further added. It processed and obtained the plate-shaped cement molded product.

Comparative Example 1 15 kg of dehydrated cake of fibrous cellulose and 45.5 k of water
3 kg of methyl cellulose and 55.5 k of water instead of g
g and g were added to the kneader, and a plate-like cement molded product was obtained in the same manner as in Example 1.

Comparative Example 2 Comparative Example 2 except that 100 kg of Portland cement and 80 kg of river sand as fine aggregate were mixed using a Henschel mixer, except that 5 kg of pulp fiber having a diameter of 10 μm and a length of 3 mm was added. A plate-like cement molded product was obtained in the same manner as in 1.

Comparative Example 3 100 kg of Portland cement, 60 kg of river sand as a fine aggregate, 2 kg of methyl cellulose as an extrusion aid, and 3 kg of fiberized cellulose having a diameter of 0.3 μm and a length of 40 μm were sufficiently mixed using a Henschel mixer. Then
I put it in a kneader. To this, 37 kg of water was added and mixed to obtain a kneaded cement composition. A plate-like cement molded product was obtained from this composition in the same manner as in Example 1.

Evaluation The plate cement molded articles obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated for bending strength, extrusion moldability and surface smoothness. The evaluation method is as follows. The results are shown in Table 1.

(Bending Strength) The plate-shaped cement molded product was left standing for 1 day in a wet state and then cured in water at 20 ° C. for 27 days to be cured. For this cured product, an autograph "IS-10T" manufactured by Shimadzu Corporation was used and a span of 15 was used.
Bending strength was measured by centralized loading at 0 mm and a loading speed of 1 mm per minute.

(Extrusion Moldability) Extrusion speed during extrusion molding (c
m / min). It is shown that the higher the extrusion rate is, the better the moldability is.

(Surface smoothness) A plate-like cement molded product was cured, and its surface roughness (mm) was measured using a roughness tester. The evaluation criteria are as follows. ◯: Surface roughness is less than 0.2 mm. Δ: Surface roughness is 0.2 to 0.4 mm.

[0039]

[Table 1]

[0040]

The cement composition according to the present invention contains asbestos fibers because it contains fibrous cellulose having a diameter of 0.01 to 1 μm and a length of 1 to 5 mm obtained by a crushing method. A cement extrusion molded product having high strength and good surface smoothness can be realized at low cost without using it.

Since the extrusion molding aid of the cement composition according to the present invention comprises the above-mentioned fibrous cellulose, it can be provided at a lower cost than conventional extrusion molding aids.
Moreover, a cement extruded product having good surface smoothness can be realized.

Claims (3)

[Claims] 1. Cement 100 parts by weight, fine aggregate 50-150 parts by weight, diameter 0.01-1 μm, length 1 obtained by crushing method
A cement composition containing 2-10 parts by weight of -5 mm fiberized cellulose. 2. The cement composition according to claim 1, wherein the fibrous cellulose is in the form of an aqueous dispersion containing the same or a dehydrated cake thereof. 3. A diameter of 0.01 to 1 obtained by a crushing method.
An auxiliary agent for extrusion molding of a cement composition, which comprises μm and a fiberized cellulose having a length of 1 to 5 mm.