JPH0789757A - Method for producing non-asbestos extrusion molded cement board - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a method for producing a non-asbestos extrusion molded cement board which is inexpensive, has high strength and impact resistance. The method for producing a non-asbestos extrusion molded cement board of the present invention is a non-asbestos extrusion molding from a cement composition for extrusion molding containing cement, siliceous raw material, aggregate, organic fiber and extrusion molding aid. In the method for producing a cement board, the Blaine value of 4000 is used as the siliceous raw material.
Fly ash in the range of 10000 cm ² / g is used, and the weight ratio of cement and fly ash is 7 /.
The mixture is mixed with other raw materials in a range of 3 to 5/5, and water is further added and kneaded to form a cement composition for extrusion molding, and then the composition is extrusion-molded to obtain a molded body obtained. 120
It is characterized by being autoclaved at a temperature of ~ 200 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-asbestos extrusion molded cement board used as a wall material for construction.

[0002]

2. Description of the Related Art Conventionally, extrusion-molded cement boards have been subjected to autoclave curing using cement, silica stone powder, aggregate and asbestos as main raw materials. Among these main raw materials, asbestos was an important raw material because it had a great effect on improving the strength and impact performance of the molded body. However, asbestos is considered to affect the human body in terms of environmental hygiene, and non-asbestos has been required.

Non-asbestos products are produced by using wood pulp or other synthetic fibers alone or in combination in place of asbestos, but they do not have sufficient strength or have poor impact performance. Moreover, hydrothermal reaction between cement and silica stone powder produces calcium silicate,
In order to develop strength, the reaction must be carried out at a relatively high temperature. At this time, many organic fibers were deteriorated and decomposed by temperature, and it was often meaningless for the initial purpose of reinforcement and improvement of impact resistance.

As means for solving such a problem, JP-A-3-187962 and JP-A-4-46045 propose a method of curing low temperature autoclave by combining silica sand and fly ash as a silicic acid raw material. . For example, in JP-A-3-187962, a cement, a siliceous raw material, an organic reinforcing fiber, a lubricant, a filler, an extrusion molding cement composition prepared by blending methylcellulose as an extrusion molding aid, the siliceous raw material is It is considered to be silica sand and fly ash, and the mixing ratio of this silica sand and fly ash is 8
Disclosed is a method for producing an inorganic extruded product, which comprises extruding a product of 5:15 to 30:70 and subjecting it to autoclave curing under a steam pressure of ^{2 to} 6 kg / cm ² . Further, in Japanese Patent Laid-Open No. 4-46045, a hydraulic material such as cement is mixed in a ceramics-based composition in which silica sand, which is a natural or industrial waste, and fly ash are mixed as a siliceous material, and the Blaine value as the silica sand. 4000
Use the cm ² / g or more 10000 cm ² / g or less of natural or industrial waste sand, and after shaping to hydrolyze and the product shape to the ceramic-based formulations, pressure conditions 4 kg / cm ² or less of Autoclaved There is disclosed a method for manufacturing a ceramic product characterized by being cured by. However, as is clear from FIG. 1 of JP-A-4-46045, in order to obtain a practical bending strength of the product, the Blaine value of silica must be close to 10000 cm ² / g, The cost of crushing silica sand to this extent is extremely high. Also, the bending strength is not sufficiently high.

Accordingly, an object of the present invention is to provide a method for producing a non-asbestos extrusion molded cement board which is inexpensive, has high strength and impact resistance.

[0006]

That is, a method for producing a non-asbestos extrusion molded cement board according to the present invention is a method for extrusion molding containing cement, a siliceous raw material, an aggregate, an organic fiber and an extrusion molding aid. In the method for producing a non-asbestos extrusion molded cement board from a cement composition, a Blaine value of 4000 to 10000 cm ² /
Use fly ash in the range of g, mix the cement and fly ash in the weight ratio of 7/3 to 5/5 with other raw materials, and further add and knead water for extrusion molding It is characterized in that a cement composition is formed, then the composition is extruded, and the obtained molded body is subjected to autoclave curing at a temperature of 120 to 200 ° C.

[0007]

In the method for producing a non-asbestos extrusion molded cement plate of the present invention, attention is paid to cement and siliceous reaction under hydrothermal reaction conditions in an autoclave, and silica sand and fly ash are used as conventional siliceous material sources. Where used, fly ash, which is rich in amorphous silicic acid and has higher solubility than silica sand, is used alone. Further, in order to increase the reactivity of the fly ash, the fly ash is subjected to a pulverization treatment to have a Blaine value of 4000 to 10000 cm ² /
By setting the content within the range of g, the inventors have found a means by which the organic fiber used as a reinforcing material can be more effectively used without lowering the performance even when the conventional reaction temperature of about 180 ° C. is lowered by several tens of degrees Celsius. . Of course, even if the reaction is carried out at a temperature of 180 ° C. or higher as usual, the strength can be higher than that of the conventional product. Further, fly ash, which is an industrial waste discharged from a coal-fired power plant, can be effectively used as a siliceous raw material.

As the other raw materials used in the method of the present invention, the raw materials conventionally used for extrusion molded cement boards are applied. Specifically, the weight ratio of cement / fly ash is adjusted to be in the range of 7/3 to 5/5, and other materials such as aggregate, wood pulp, organic fiber and auxiliary agent can be blended as necessary.

[0009] Here, the fly ash used in the present invention, Blaine 4000~10000cm ² / g, preferably 4000~8000cm ² / g, must more preferably be pulverized to about 4000~6000cm ² / g . However, the normally available fly ash has a Blaine value of about 3000 cm ² / g,
It is relatively easy to set the Blaine value of fly ash to 4000 cm ² / g or more. However, 10000c
It is not easy to grind to a Blaine value exceeding m ² / g, and in terms of cost, an effect commensurate with this cannot be expected.

If the weight ratio of cement / fly ash is larger than 7/3 or smaller than 5/5, it is impossible to obtain a high strength non-asbestos extrusion molded cement board.

The other raw materials are not particularly limited in terms of blending ratio and kind, and those conventionally used may be used as necessary. Examples of aggregates include calcium carbonate, wollastonite, talc, mica, perlite and the like. Examples of the organic fibers include cellulosic fibers such as wood pulp, polypropylene fibers, acrylic fibers and the like. Examples of extrusion aids include methyl cellulose and carboxymethyl cellulose.

After adding the above-mentioned raw materials, mixing and kneading, and extruding into a predetermined shape, 120 to 20
Under saturated steam pressure of 0 ° C, preferably 140 to 190 ° C,
Hydrothermal reaction is carried out in the autoclave to cure the molded body. At this time, due to the thermal characteristics of the blended organic fiber,
It is preferred to select the reaction temperature. Here, when the reaction temperature is lower than 120 ° C., the hydrothermal reaction is not sufficiently performed,
High strength non-asbestos extruded cement board cannot be obtained. On the other hand, if the temperature exceeds 200 ° C, the non-asbestos extrusion molded cement board becomes brittle and the dispersion of strength becomes large, which is not preferable.

By the above method, a non-asbestos extrusion molded cement board having high strength and high impact resistance can be manufactured.

[0014]

【Example】

Examples 1 to 8 Cement and pulverized fly ash were weighed at the mixing ratios shown in Table 1 so that the weight ratio was 5/5 and 6/4, and extrusion molding was performed. 1 for the obtained molded body
Autoclave treatment was performed at 70 ° C. and 140 ° C., and after drying, bending strength and Charpy impact value were measured. As a result, it was found that the cement board has high strength and high impact resistance. The fly ash used in this example is
The Blaine values are 4000 cm ² / g, 5000 cm ² / g and 8000 cm ² / g. The relationship between the Blaine value of fly ash and the bending strength of the obtained cement plate (cement / fly ash weight ratio 6/4) is shown in FIG.

Comparative Examples 1 and 2 Cement and fly ash having a Blaine value of 3000 cm ² / g were weighed in the mixing ratio shown in Table 1 so that the weight ratio was 6/4, and extrusion molding was performed. Then, the same treatment as in the example was performed. The autoclave temperature in Comparative Example 1 was 170 ° C, and the autoclave temperature in Comparative Example 2 was 140 ° C. As a result, it was found that the strength was remarkably low as compared with the examples. The relationship between the Blaine value of fly ash and the bending strength of the obtained cement board is shown in FIG.

Comparative Examples 3 to 5 Cement and fly ash having a Blaine value of 5000 cm ² / g were weighed at the blending ratios shown in Table 1 so that the weight ratio was 8/2 and 4/6, and then carried out. The same process as the example was performed. As a result, the strength was lower than that of the example.

Comparative Examples 6 to 7 Cement and fly ash having a Blaine value of 5000 cm ² / g were weighed in the mixing ratio shown in Table 1 so that the weight ratio was 6/4, and extrusion molding was carried out. Then 11
Autoclave treatment was performed at 0 ° C. and 210 ° C., and after drying, bending strength and Charpy impact value were measured. As a result, the strength was lower at the reaction temperature of 110 ° C. and the Charpy impact value was remarkably lower at the reaction temperature of 210 ° C. than in Examples 1 to 6.

Comparative Example 8 Cement and silica stone powder having a Blaine value of 4000 cm ² / g were weighed in the mixing ratio shown in Table 1 so that the weight ratio was 6/4, and extrusion molding was carried out. Then, autoclave treatment was performed at 140 ° C., and bending strength was measured. As a result, the strength was lower than in Examples 1 to 6.

Comparative Example 9 Cement and fly ash having a Blaine value of 12000 cm ² / g were weighed at a mixing ratio shown in Table 1 so that the weight ratio was 6/4, and extrusion molding was carried out. Then 14
Autoclave treatment was performed at 0 ° C., and bending strength was measured. As a result, there is no change in strength as compared with Examples 1 to 6,
Grinding with a Blaine value of 12000 cm ² / g proved to be meaningless. The relationship between the Blaine value of fly ash and the bending strength of the obtained cement board is shown in FIG.

[0020]

[Table 1]

[0021]

According to the method for producing a non-asbestos extrusion molded cement board of the present invention, fly ash having a Blaine value of 4000 to 10000 cm ² / g as a siliceous raw material by pulverization is used as a cement / fly ash weight ratio. Is used in the range of 7/3 to 5/5, the temperature of autoclave curing can be lowered by several tens of degrees Celsius as compared with the conventional method, whereby the range of selection of the organic fiber used as the reinforcing raw material can be reduced. Can be extended.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the Blaine value of fly ash and the bending strength of a cement plate (cement / fly ash weight ratio 6/4).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C04B 16:06 16:02 24:38) (72) Inventor Kazuo Yokoyama 4 Tokodai, Ishioka City, Ibaraki Prefecture -13-2

Claims (1)

[Claims] 1. A method for producing a non-asbestos extrusion molded cement board from a cement composition for extrusion molding, which comprises cement, a siliceous raw material, aggregate, organic fibers and an extrusion molding aid. Value 4000
Fly ash in the range of 10000 cm ² / g is used, and the weight ratio of cement and fly ash is 7 /.
The mixture is mixed with other raw materials in a range of 3 to 5/5, and water is further added and kneaded to form a cement composition for extrusion molding, and then the composition is extrusion-molded to obtain a molded body obtained. 120
A method for producing a non-asbestos extrusion molded cement board, which comprises performing autoclave curing at a temperature of up to 200 ° C.