JPH01141857A - Cement composition - Google Patents

Abstract

PURPOSE:To obtain cement composition wherein extrusion molding is easy and a produced, cured and molded body is excellent in strength and harmful asbestos is not incorporated by allowing the specified amount of cement, sepiolite and a cellulose- base admixture to be incorporated. CONSTITUTION:This cement composition is constituted by allowing 3-50pts.wt. sepiolite and 0.1-10pts.wt. cellulose-base admixture for 100pts.wt. cement to be incorporated. When using this composition, a molded cement body which has high strength and is excellent in shock resistance is obtained by extrusion molding with good moldability at high efficiency. Such molded cement body is preferably used as the floor material, etc., of multiple dwelling houses. Furthermore, hazard of carcinogenesis due to waste dust of asbestos is eliminated even in a producing process and even at a time of use because asbestos is not contained. In the above-mentioned composition, when sepiolite is excessively little, moldability is impaired and furthermore density of the cured molded body is enlarged and shock resistance is deteriorated. On the other hand, when it is excessive, strength of the molded body is reduced. Furthermore, when the cellulose-base admixture is excessively little or excessive, viscosity at a time of mixing is made low or high respectively and therefore moldability is degraded in both cases.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cement composition from which cement molded bodies for use in flooring, walling, etc. can be advantageously prepared.

(Prior Art) Cement molded bodies are used as building materials such as flooring materials and wall materials. The cement molded body is prepared by, for example, pouring a cement composition containing Portland cement, water, and other components as necessary into a desired mold and hardening it.

The cement molded body is removed from the mold after it has hardened to some extent and is sufficiently hardened, but continuous production is not possible and production efficiency is low. Therefore, a method of preparing a cement molded body by extrusion molding (dry method) has been adopted. When obtaining a cement molded body by extrusion molding, it is necessary to improve fluidity in the manufacturing process. Increasing the amount of water may be considered to increase the fluidity of the cement composition, but even if the amount of water is increased, only the water will flow out before the composition material is extruded by pressure, resulting in poor molding.

Furthermore, even if a molded product having a desired shape is extruded, the shape is distorted and the desired hardened cement molded product cannot be obtained. Therefore, asbestos has usually been added to the cement compositions used.

This asbestos is added for the purpose of increasing the fluidity of the slurry cement composition during the manufacturing process and maintaining the shape of the extruded uncured molded product. Asbestos again. It also serves to improve the strength of the final product obtained. However, asbestos is designated as a specified chemical substance, and its carcinogenicity has become a problem.

Although standards for use are established when asbestos cement molded bodies are manufactured, molded bodies that do not use asbestos are currently desired due to the problem of dust generation during manufacture and use.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned conventional drawbacks, and its purpose is to provide a hardened molded product that is easy to extrude, has excellent strength, and is free from harmful asbestos. An object of the present invention is to provide a cement composition containing no.

(Means for Solving the Problems) The cement composition of the present invention contains cement, sepiolite, and a cellulose-based admixture, thereby achieving the above object.

Examples of the cement contained in the cement composition of the present invention include Portland cement and blast furnace cement.

Any known cement can be used, such as alumina cement.

Sepiolite is contained in cement compositions.

For example (OHz) a (OH) 4Mg5Si+ 2
030 - Magnesium silicate compound represented by 6-81zO. This sepiolite is a clay mineral with a double-chain structure, and exists in the form of fibers, powdery particles, plates, etc. Sepiolite exists in either an α-type or a β-type crystal structure, and α-type sepiolite (α-seviolite), which naturally exists in a fibrous form, is preferably used. The fiber diameter of this fibrous sepiolite is 0.01
~0.30 μm, preferably about 0.15 μm; and the fiber length is 2 μm or more, preferably 100 μm or more. Normally, naturally occurring sepiolite is appropriately pulverized or mixed with water and stirred to defibrate it to obtain sepiolite of a desired size. Sepiolite is included in cement compositions.
It is contained in an amount of 3 to 50 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of cement. If the amount is too small, the moldability of the cement molded product will be poor. Furthermore, the density of the resulting cured cement molded body increases, resulting in an increase in overall weight. Impact resistance also decreases. If it is in excess, the strength of the molded article will decrease.

The cellulosic admixture imparts water retention to the 9 composition. Therefore, when a water-containing composition is extruded under pressure, water is retained within the composition, preventing separation and dehydration, and improving moldability.

Since the composition containing the cellulose admixture has an appropriate viscosity, the composition has increased fluidity and can be easily extruded. The shape retention of the molded article until it hardens is also improved. As the cellulose-based admixture, cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and hydroxymethylcellulose are used. The cellulose-based admixture is contained in the composition in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of cement. If it is too small, the viscosity of the composition will be low when mixed, whereas if it is too large, the viscosity will be high.

Both have poor moldability.

The composition contains reinforcing fibers as necessary. The reinforcing fibers are used to improve the bending strength and impact strength of the resulting molded product. For example, organic fibers, pulp, metal fibers, etc. can be used. Organic fiber materials include vinylon, polypropylene, polyethylene, carbon, etc.

Alkali-resistant materials such as aramid are used.

The type of pulp is not particularly limited, but it can be used for cement coagulation and
Waste paper pulp that does not adversely affect curing is more suitable.

The diameter of the reinforcing fibers is 1 to 100 μm, and the fiber length is 3 to 20 m.
m is appropriate. The reinforcing fibers are contained in the composition in an amount of 10 parts by weight or less, preferably 0.2 to 10 parts by weight, per 100 parts by weight of cement.

If the reinforcing fibers are in excess, the composition will have poor dispersibility when mixed, resulting in a decrease in the strength of the resulting molded product.

In order to manufacture a cement molded body using the composition of the present invention, a process similar to conventional cement extrusion molding can be adopted. For example, first, the above cement, sepiolite, and cellulose admixture are triblended. An appropriate amount of water is added to the mixture for wet blending, and then thorough kneading is carried out using a kneader. The obtained plastic kneaded material is introduced into an extrusion molding machine having a desired mold, and extrusion molding is performed under pressure. The extruded molded product having the desired shape is cured at room temperature under conditions such that the surface of the molded product does not dry (2), for example, covered with a polyethylene film.

Or, in order to cure in a short time, under specified conditions (e.g. temperature 40-60°C, humidity 90-100%)
It hardens by being left for a long time (curing). The above blending process, kneading process and extrusion molding process include
In either case, general-purpose equipment can be used.

(Function) When extrusion molding is performed using the cement composition of the present invention, the kneaded material has sufficient fluidity in the extruder, the flow rate becomes uniform, and the extruded uncured molded product progresses in hardening. It has sufficient shape retention until Such good properties are due to the fact that the water-containing composition containing Seviolite has thixotropy, so it has good fluidity under pressure and sufficient shape retention after extrusion.

This is thought to be mainly due to. Since Seviolite in the present composition is a relatively long fiber, the above-mentioned moldability and shape retention are further improved. This is because the kneaded product further contains a cellulose-based admixture.

Maintains appropriate viscosity and has excellent fluidity and shape retention after extrusion. Even when molding is performed using a mold having a complex irregular cross-sectional shape, the molding can be easily performed without requiring the conventional dehydration process. The extruded uncured molded product has good shape retention and does not deform before it hardens. Since the obtained cured molded product contains Seviolite, the molded product has sufficient strength and impact resistance. Such molded bodies are suitably used as flooring materials for houses.

According to the present invention, a high-strength cement molded body suitable for flooring can be easily manufactured without using conventional asbestos fibers. As asbestos fibers are not used, there is no risk of cancer caused by asbestos dust during the manufacturing process or during use.

(Example) The invention will be explained below with reference to examples.

Implementation ■ Preparation of soil (A) plastic kneaded product: (Hereafter blank) Cement composition Blend amount Ingredients (Parts by weight) Each component other than water of the cement composition of the above formulation was mixed with a mixer (all-purpose mixer; Sanei Seisakusho) (manufactured by S.A.) and mixed for 3 minutes. Water was added thereto, and after mixing for about 31 minutes, the mixture was sufficiently kneaded using a kneader (auger type extrusion kneading 1''& MP-100 type; manufactured by Miyazaki Tekko Co., Ltd.) to obtain a plastic kneaded product.

(B)-1 Preparation of cement molded product: The kneaded product obtained in section (A) was processed using a vacuum extrusion molding machine equipped with a flat trial mold (opening size 250 mm x thickness 15 mm). MV-FM-A-1i (manufactured by Miyazaki Tekko Co., Ltd.) hopper, and extrusion molded it to a width of 250 mm and a thickness of 1.
A flat plate sample with a length of 5 am and a length of 50 cm was prepared.

The extrusion pressure and extrusion amount per unit time at this time were measured. The extrusion pressure was measured by measuring the pressure in the resistance section from the barrel of the extruder to the mold using a Bourdon tube pressure gauge. The extrusion amount per unit time is the length (cm/m i
n ) was measured and calculated using the 9th order equation.

Per unit time a: Thickness of the extruded flat sample (cm) b: Width of the extruded flat sample (C1l) C: Length of the extruded flat sample (cm) time,
After leaving at room temperature (preliminary curing), 50℃, R895
% or more for 12 hours (first curing). This flat plate-shaped molded unit was immersed in water at 20° C. for about 4 weeks.

(B) Preparation of a molded body with a Ω-shaped cross section: As shown in FIG. 1(a), an inner mold 11 in which a protrusion 11a having a trapezoidal cross section is disposed along the longitudinal direction and the protrusion A mold having an outer mold 12 in which a concave groove 12a into which the upper part of the mold was fitted was disposed along the longitudinal direction was prepared. The widthwise dimension of the top surface of the protrusion of this inner mold 11 is 7cm+, the widthwise dimension of the bottom surface is 9cm, and the height is 5cm. The widthwise dimension of the opening of the concave groove of the outer mold 12 is 11.5cm, and the widthwise dimension of the inner deep part is 9.5cm.
cm, and the depth is 5 cm. Separately, an uncured long plate-shaped cement molded body (25 cm x 1.5 cm x 35 cm) was obtained by extrusion molding in the same manner as in Section (B)-1. This uncured long plate-shaped cement molded body 3 is shown in Figure 1 (a
), each side in the width direction is placed on a pair of support plates 21 and 22 that are arranged opposite to each other across the protrusion of the inner mold 11.
As shown in FIG. 1, the inner mold 11 and the outer mold 1 are
Press with 2 (pressure 10kg/cffl, 10 seconds)
An uncured molded body 30 having an Ω-shaped cross section as shown in FIG. 1(C) was obtained.

This uncured molded body was cured according to Section (B)-1.

As shown in FIGS. 2(a) and 2(b), a cured molded body 31 having a concave portion projecting upward was obtained.

(Performance evaluation of CLI molded product: Cut the flat plate-shaped molded product obtained in (B)-1 into 25 mm width and 240 mm length (cut perpendicular to the extrusion direction) at L, 105°C. After drying for about 48 hours in a gear oven, the samples were allowed to cool for 24 hours.The samples were supported at intervals of 200 mm.

A force was applied to the central portion at a bending speed of 2.5+n+n/min to measure the bending strength (bending strength test). Separately, the sample after immersion was cut into pieces of 250 mm in width and 250 mm in length (cut perpendicular to the extrusion direction) and subjected to oven treatment in the same manner as above. This sample was placed on flat river sand, and a 1 kg steel ball was dropped from a height of 2 m onto the center of the sample to observe whether any abnormality was observed in the sample (impact strength test). The results of each test are shown in the table below.

(C)-2 Performance evaluation of molded product: The cured molded product 31 obtained in section (B)-2 was cut into a length of 30 cm perpendicular to the longitudinal direction, and the depth of the recess was (g))) was measured with a caliper. The results are shown in the table below.

Backyard Dish I Same as Example 1 except that the amount of sepiolite was 30 parts by weight, the amount of methylcellulose was 1.2 parts by weight, and the amount of water was 50 parts by weight. The results are shown in the table below. The results of Examples 3 and 4 and Comparative Examples 1 and 2 are also shown in the table below.

The amount of main sepiolite was 20 parts by weight, the amount of water was 45 parts by weight, and vinylon fiber (average fiber diameter 12 μm) was added.

The procedure was the same as in Example 1 except that 1.0 part by weight of the fiber (fiber length: 6 mm) was used.

The procedure was the same as in Example 1, except that the amount of pointed plate ecepiolite was 40 parts by weight, the amount of methylcellulose was 0.8 parts by weight, and the amount of water was 60 parts by weight.

The procedure was the same as in Example 1 except that methyl cellulose was not used and the amount of water was 40 parts by weight. When extrusion molding was attempted using the cement composition of this comparative example, the moldability was poor and the desired molded product could not be obtained.

This fiλ does not use sepiolite and the amount of methyl cellulose is 10
The same as Example 1 except that the parts by weight and the amount of water were 35 parts by weight.

(The following is a blank space) From Table 9, it can be seen that according to the present invention, a cement molded body can be obtained with good moldability by extrusion molding. The obtained molded product has excellent bending strength and impact resistance.

It will not deform even if it is hydrated by being immersed in water for a long period of time.

(Effects of the Invention) When the composition of the present invention is used, a cement molded body having high strength and excellent impact resistance can be obtained by extrusion molding with good moldability and high efficiency. Such cement molded bodies are used, for example, as decking materials for housing complexes.

Suitable for use as flooring materials such as hallway materials. Since it does not contain asbestos, there is no risk of cancer caused by asbestos dust either during the manufacturing process or during use.

[Brief explanation of the drawing]

1(a) to 1(C) are explanatory diagrams showing an example of the step of press working an uncured long plate-shaped cement molded body obtained by extrusion molding using the composition of the present invention, and FIG. (a
) and Q:1) are the cross sections Ω obtained by the press processing.
FIG. 2 is a perspective view and a sectional view of a shaped cement body. 3... Uncured long plate-shaped cement molded body, 30... Ω-shaped cross-section cement molded body. that's all

Claims (1)

[Claims] 1. Sepiolite is 3 to 3 to 100 parts by weight of cement.
50 parts by weight, and 0.1 to 10 parts by weight of cellulose admixture.
Cement composition contained in parts by weight. 2. The composition according to claim 1, wherein the sepiolite has a fiber length of 100 μm or more.