JP2636974B2 - Extrusion molding method for cement products - 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 product, and more particularly, to a method for extruding a cement product which does not require an extrusion aid.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a cement product, a cement slurry is supplied to an extruder, a product having a predetermined cross-sectional shape is extruded from a die, and the product is cut into an appropriate length to form a product and cure and harden. Molding methods are well known. This extrusion molding method has an advantage that it is very advantageous for mass production because it can continuously mold even a product having a complicated cross-sectional shape.

[0003]

[Problems of the prior art] However, when extruding a cement product, the concentration of the extruded cement slurry is usually 60% or more (solid content 60% or more, moisture content) to maintain the shape retention of the product immediately after extrusion. Therefore, there is a problem that the dispersibility of the reinforcing fibers is poor due to poor fluidity at the time of mixing the raw materials, and a slurry having sufficient strength cannot be obtained.

Further, the extruder requires a large horsepower due to flow resistance, and it is necessary to add an extrusion aid such as methylcellulose to reduce the extrusion resistance, resulting in an increase in material costs. was there.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has been made to provide a method for extruding a cement product in which extrusion resistance is reduced and an extrusion aid such as methylcellulose is not required. It is.

[0006]

That is, the method for extruding a cement product according to the present invention comprises the following steps.
Water is added to an inorganic composition consisting of 5050% by weight, pulp fiber and other reinforcing fibers 5-10% by weight, and other necessary aggregate lightweight aggregates 5 to 10% by weight to obtain a slurry concentration of 30 to 50%. The molding is extruded from a machine, and immediately after the molding, the molded body is dewatered by roll pressure and suction, and then cured.

[0007]

[Function] In the extrusion of cement products, the slurry must have a slurry concentration of 60% or more (solid content of 60% or more and moisture of 40% or less) as described above, in order to impart the shape retention of the product immediately after extrusion. Must. On the other hand, when the slurry concentration is 60% or less, especially the slurry concentration is 50% or less, the fluidity of the slurry is considerably improved, and the effect of improving the uniform mixing and extrusion resistance is remarkable. Therefore, the present inventors examined various minimum slurry concentrations within a range that can maintain the shape retention property immediately after molding, and found that the slurry was combined with a step of removing excess moisture by roll pressing and suction. It was confirmed that an extremely accurate molded product could be molded in the concentration range of 50% to 30%.

That is, in the present invention, when the slurry concentration is higher than 50%, the extrusion resistance increases and the addition of an extrusion aid such as methylcellulose becomes indispensable, but uniform mixing is not sufficiently achieved, and the slurry concentration is reduced to 30%. When the concentration is lower than 10%, it is advantageous in terms of extrusion resistance and uniform mixing, but it has been found that the shape of the molded product cannot be completely maintained even when the roll pressing and suction steps are combined.

[0009]

Next, an embodiment of the present invention will be described. A mixture of 40% by weight of cement, 40% by weight of silica sand, 10% by weight of pulp fiber and 10% by weight of pearlite was mixed by dry mixing uniformly, and then water was added to make a slurry with a concentration of 50% and 30%. As shown in FIG. 1, a molded plate 2 having a thickness of 2 cm and a width of 25 cm is extruded from the extruder 1, and immediately thereafter, the surface is compressed by a rubber roll 3 at a linear pressure of 1 kg / cm, and at the same time, is sucked from the back surface at 400 mmHg from the suction box 4. Dehydration was performed.

Next, the formed plate 2 is taken out of the take-up conveyor 5.
The extruded plate 2 was cut every 45 cm, and steam-cured in an autoclave. The test plate 2 was subjected to a crack test and a JIS No. 4 bending test to obtain the results shown in Table 1.

In Table 1, Comparative Example 1 was prepared by extruding a mixture of the above Example with a slurry concentration of 60% and adding 1% by weight of methylcellulose to the composition of the above Example. This shows the case without pressurization and suction.

As apparent from Table 1, in the embodiment of the present invention, the bending strength was 1 despite the slurry concentration being 30%.
A strength of 00 kg / cm ² which was not seen in the other examples and comparative examples was obtained, and it was confirmed that even when the slurry concentration was set to 50%, the strength was superior to that of the other comparative examples.

[0013]

[0014]

As described above, according to the method of the present invention, the extrusion performance can be improved by lowering the slurry concentration, and a large number of highly accurate molded articles can be produced without requiring an extrusion aid such as methyl cellulose. It becomes possible to mold into.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus for performing the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Molding plate 3 Rubber roll 4 Suction box 5 Pick-up conveyor

Claims (1)

(57) [Claims] 1. Water is added to an inorganic composition comprising 40 to 50% by weight of cement, 40 to 50% by weight of silica sand, 5 to 10% by weight of reinforcing fibers such as pulp fiber, and 5 to 10% by weight of other necessary aggregate lightweight aggregate. In addition, the slurry concentration is adjusted to 30 to 50%, the slurry is extruded from an extruder, and immediately after the molding, the molded body is dewatered by roll pressure and suction, and thereafter cured, and then extruded. Molding method.