JP2950187B2 - Manufacturing method of cement building materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cement building material. In particular, the present invention relates to a method for manufacturing an extruded cement building material in which curing after extrusion is performed under specific conditions.

[0002]

2. Description of the Related Art Conventionally, in order to manufacture cement building materials (hereinafter, also simply referred to as molding materials) such as wall materials and floor materials, aggregates and reinforcing fibers are mixed with cement and kneaded with water. Is passed through, for example, an extrusion molding machine to obtain a molding material, and the molding material is received on a pallet in order to facilitate handling during post-treatment such as curing.

Next, the pallets are stacked and transferred to a curing room. After curing at a high temperature in this curing cabinet, the cured molding material is separated from the pallet and dried to adjust the water content in the material. Alternatively, after the high-temperature heat curing, high-temperature and high-pressure curing (autoclave curing) may be performed.

When the materials received on this pallet are stacked and transferred to a curing cabinet for curing, the temperature inside the curing cabinet is 40 ° C.
It is generally cured at ~ 80 ° C and 80-100% humidity. In particular, in the early stage of curing, the temperature must be 60 ° C or lower. This is because, when the material is set to a high temperature condition in the early stage of the curing reaction, the evaporation phenomenon of water becomes active inside the material, and the material expands inside the material which becomes a passage of the vapor, so that normal curing cannot be performed. .

[0005] In addition, the humidity is desirably a condition of 100% humidity at which the material does not dry. In this case, on the contrary, a large amount of dew is generated on the surface of the material, resulting in a defective surface or dew condensation on the back surface of the pallet. Drops on the surface of the material as water droplets, resulting in a condition close to breathing, which causes efflorescence (white flower phenomenon). Conversely, when the humidity is lowered, the moisture in the material evaporates, so that the material shrinks to cause dimensional defects or prevent a normal curing reaction.

For example, in Japanese Patent Application Laid-Open No. 58-135185, in order to prevent the drying during curing, a molding material placed on a pallet as shown in FIG. However, in this case, the moisture evaporated from the molding material is reabsorbed on the surface of the molding material, causing a surface defect. This is because the polyethylene sheet is in contact with the molding material, so that the evaporated moisture is condensed on the polyethylene sheet and absorbed by the molding material.

[0007] For this reason, in Japanese Patent Application Laid-Open No. 4-308702, the surface of the curing material is covered with a ventilated waterproof sheet, and the moisture evaporated from the material is discharged outside the sheet. A way to avoid this has been proposed. However, applying a waterproof sheet to all pallets one by one at the time of manufacturing has many problems in terms of efficiency and economy. Not practical.

Therefore, in the process which has been put to practical use, the initial condition in the curing cabinet is that the temperature is gradually increased at a low temperature of 30 to 40 ° C. where no dew condensation occurs and drying does not easily occur. Although a method is used, there are problems such as a long curing time, and dew condensation and drying cannot be completely prevented.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive and efficient method for producing an excellent cement building material which has solved the drawbacks of the prior art. Furthermore, a specific object of the present invention is to provide a method for producing a cement material that reduces the occurrence of dew condensation or drying and cures efficiently when curing the molded material received on a pallet in a stacked state after molding. It is to be.

[0010]

Means for Solving the Problems The present inventors examined the occurrence of dew condensation, shrinkage deformation due to drying, and the development of strength of extruded cement building materials by changing the temperature and humidity of the curing cabinet in various ways. After receiving the molding material on the pallet, the pallets are stacked, and before being transferred to the curing cabinet, both ends of the pallet are sealed to reduce the influence of the outside air. The present invention was found to be effective in preventing hydration and preventing the material from drying out, and to increase the temperature of the material.

Here, the gist of the present invention is that a cement mixture is kneaded and molded, the obtained molding material is received on a pallet, and the pallets are stacked in a stack under a steam atmosphere.
A method of curing the molded material by transferring the cured material to a curing cabinet for curing as a cement building material, and prior to transferring the molded material to the curing cabinet, the molding material stacked and stacked on the pallet is cured in a surrounding curing atmosphere. A method for producing a cement building material, characterized in that a state in which moisture does not flow in and out of the curing atmosphere and a surface of the molding material are not in direct contact with the curing atmosphere, and then transferred to a curing chamber for curing. . According to a preferred embodiment of the present invention, the curing temperature is 40 ° C. or higher. Note that an extrusion method was used as a molding method.

[0012]

Next, the operation of the present invention will be described based on experimental results. First, a cement mixture was prepared at the following mixing ratio. Normal Portland cement 40 parts by weight Powdered silica sand 30 parts by weight Perlite 30 parts by weight Cellulose fiber 5 parts by weight Thickener methylcellulose 1.5 parts by weight Water Appropriate amount.

The mixture thus obtained is kneaded and extruded to obtain a molded material having a width of 100 mm, a thickness of 10 mm, and a length of 800 mm.
850 mm stainless steel pallets 1 are stacked on each other so as to form a gap of 50 mm each by a spacer 2, and then put into a curing cabinet (not shown).
Cured under the conditions shown in the table. At this time, the occurrence of dew condensation, the amount of change in shrinkage, and the strength development of the molding material were investigated, and the results are shown in Table 1.

[0014]

[Table 1]

[0015] From the results shown in Table 1, when the humidity of the initial curing chamber was 95% or more, dew condensation on the molding material and water drops from the back surface of the pallet were observed at any temperature. Also,
When the humidity was 60 to 70%, the shrinkage due to drying was large.

When the initial curing temperature was 65 ° C., the molding material had a remarkable expansion phenomenon and was insufficiently cured. This is because moisture was evaporated from the inside of the molding material due to being placed in a high temperature state before the reaction, and the passage of the vapor became a void, and it became an apparently expanded state.

Under the same conditions, both open end faces of the stacked pallets 1 are sealed with a waterproof sheet.
Curing was performed in a state where inflow of steam and the like was prevented. Table 2 shows the results of the examination. Despite the difference in environmental conditions, no condensation was observed and the shrinkage and deformation were extremely small. This is due to the effect of sealing the open end of the pallet, which has greatly reduced the ingress and egress of moisture. The strength of each material was unexpectedly high at 100 kg / cm ² or more.

[0018]

[Table 2]

FIGS. 3A and 3B show the temperature change inside the pallet when the pallet end is not sealed. As shown in FIG. 3 (A), when the sealing is not performed, the temperature rises immediately after entering the warehouse, and even after the high-temperature curing in the later stage starts, the temperature inside the pallet is slightly delayed from the temperature change in the interior of the pallet. I understand.

On the other hand, in the case of sealing, as shown in FIG. 3 (B), the temperature rise is gentle because there is no insertion (inflow) of external steam or the like by the seal, but the temperature is gradually increased and curing starts. After about 10 hours from the end, it exceeded the case where the end face was not sealed. This is because the heat generated by the cement hydration reaction increases with the progress of the cement hydration reaction, and the effect of increasing the temperature increases, and at the same time, the heat is prevented from escaping to the outside by the seal.
Thereby, it is presumed that even when the sealing is performed, the strength development is favorably performed.

As described above, the feature of the present invention is that cement building materials on a pallet in a stacked state are prevented from shrinking due to dew condensation or drying in a curing cabinet. To reduce the influence of the external environment.

Generally, the temperature of the molding material after extrusion molding is
The temperature is 40 to 45 ° C and 25 to 30 ° C in winter. When curing, naturally, the curing is carried out in a curing chamber at a temperature higher than these temperatures. Further, in curing, from the viewpoint of preventing drying, humid conditions are generally used. In this case, dew condensation occurs on materials or pallets at a temperature lower than the curing cabinet temperature.

This condensation does not cause any problem if it is slight, but sometimes causes a defect such as efflorescence. When efflorescence occurs, the adhesion to the coating film after coating is reduced. Conversely, under dry conditions where dew condensation does not occur, the molding material shrinks due to evaporation of water, causing dimensional defects.

In other words, it is important how to cure the molded material under conditions that do not cause condensation or drying, including the temperature difference between summer and winter. It is an invention.

Therefore, according to the present invention, the object can be achieved by a relatively simple method of sealing both end faces of the pallet with sheets while the pallets are stacked. The material for the seal is not particularly limited, but a thin vinyl sheet or a thin steel sheet that easily conducts heat is preferable.

According to another aspect of the present invention, a similar effect can be obtained by covering the entire stacked pallets with a box-shaped cover in addition to sealing both end surfaces of the pallets. FIG.
As shown schematically, the stacked pallets 1 (or molded bodies 3) are covered with, for example, a box-shaped curing cover 4 made of a thin steel plate. Then, it is put into a curing storage as it is and cured in the same manner as described above.

That is, one of the features of the present invention is that the molded material is brought into a state in which substantially no moisture enters and exits from the surrounding curing atmosphere during curing. Furthermore, when such a cover or sheet comes into contact with the molding material, dewed water on the inner surface of the sheet or cover is reabsorbed by the molding material, so that in order to prevent this, the sheet must not be in direct contact with the molding material. is necessary. Further, the curing temperature is set to 40 ° C. or higher because the curing effect is small when the temperature is lower than 40 ° C.

That is, the present invention is a method of curing a molded material having received a pallet in a state in which moisture does not enter or exit from the surrounding curing atmosphere. The volume of this closed space is 1.2 to 10 times the volume of the molded plate. It is desirable to be in the range of double. 1.
If it is smaller than twice, there is actually a high possibility of contact with the cover material for shielding from the curing atmosphere, and the condensed water at the contact portion will be re-absorbed into the molding material. On the other hand, if it exceeds 10 times, the volume of the closed space is large, and thus problems such as a decrease in the heating effect and unevenness of the temperature in the closed space are caused. The present invention is not limited to those formed by the extrusion molding method, but can be applied to those formed by a papermaking method or a casting method.

By the way, as already described,
In the method described in JP-A-308702, a method of covering the surface of each molded material with a breathable sheet is disclosed.However, the difference of the present invention compared with that in the case of using a sheet is as follows. It is on the street.

In the present invention, the curing is carried out in a state in which the ingress and egress of moisture from the atmosphere of the curing chamber is blocked. On the other hand, the method described in the above publication, as can be seen from the use of a breathable sheet, shows that Is allowed in and out.

When stacking pallets in a multi-stage manner, it is only necessary to place a sheet on the open end when the stacking is completed, or a box-shaped cover may be used, so that the operation efficiency is greatly improved.

[0032]

Next, the present invention will be described in more detail by way of examples. The cement compounding ratio of this example was as follows. Ordinary Portland cement 40 parts by weight Powdered silica sand 30 parts by weight Perlite 30 parts by weight Cellulose fiber 5 parts by weight Thickener methylcellulose 1.5 parts by weight Water Appropriate amount
It was molded into dimensions of 400 mm × thickness 20 mm × length 3300 mm, and the obtained molded material was received on a stainless steel pallet.

As shown in the side view of FIG. 5, the pallet 5 used in this embodiment has a center plate 6 having a width of 600 mm × thickness 3 mm, a side plate 7 having a thickness of 2 mm and a square tube of 50 mm × 50 mm. Was. As will be described later, the pallet 5 is stacked in a single row of 20 stages, and both open ends of the pallet 5 are covered with thin vinyl sheets (Examples 1 and 2) and not covered (Comparative Example 1,
Curing tests were performed on the conditions 2 and 3) shown in Table 3, respectively.

The form of stacking of the pallets 5 is shown in FIG.
As shown in the side view in (B), a single row, a double row, or more rows may be used. In this state, the end sheet is hung and sent to the curing cabinet. In Example 1, after curing in a steam atmosphere at a temperature of 60 ° C. and a humidity of 95% or more for 10 hours, an autoclave curing (180 ° C. × 5 hours) was performed, followed by drying at 110 ° C. for 3 hours.

In Example 2 , curing was performed in a steam atmosphere at a temperature of 70 ° C. and a humidity of 95% or more for 5 hours, at a temperature of 85 ° C. and a humidity of 95% or more for 5 hours, and further at a temperature of 85 ° C. and a humidity of 95% or more for 10 hours.
Dry at 110 ° C. for 8 hours. The volume of the closed space under these conditions was 3.5 times the volume of the molding material. The comparative example was cured under the same conditions except that no cover was provided. The results of the curing test at this time are summarized in Table 4.

[0036]

[Table 3]

[0037]

[Table 4]

As can be seen from these results, in Examples 1 and 2, due to the effect of the end face cover, efflorescence due to dew condensation did not occur, shrinkage deformation due to drying was small, and bending strength was high. And Comparative Examples 1 and 2,
The occurrence of efflorescence was large, and the strength of Comparative Example 2 was poor. In Comparative Example 3, the influence of drying was large, and the shrinkage deformation ratio was as large as 2%.

[0039]

Since the present invention is constructed as described above in detail, even when the curing conditions are high, humid or dry, the surroundings of the material are unlikely to be condensed and dried, and the temperature rises in the early stage of curing. Since the temperature is moderate, the curing reaction of the cement proceeds well, and the final strength is high. Therefore,
Good cement building materials can be obtained in terms of strength, dimensions and surface properties, which are industrially useful.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view illustrating a conventional example.

FIG. 2 is a schematic perspective view showing a state in which a molding material is received on a pallet, a spacer is inserted, and the pallet is stacked.

FIG. 3 (A) shows the temperature change of the molded material when cured in a stacked state without covering both end surfaces with a vinyl sheet, and FIG. 3 (B) also shows FIG. 3 (A). 7 is a graph showing the results when covering is performed under the conditions shown in FIG.

FIG. 4 is a schematic explanatory view of another modified example of the present invention.

FIG. 5 is a side view showing a general pallet shape for receiving a cement building material.

FIG. 6 shows a stacked state when a molding material is received and cured on the pallet of FIG. 5, and FIG. 6 (A) shows a case of one row, and FIG. 6 (B)
FIG. 3 is a schematic side view showing a case of two rows.

[Explanation of symbols]

 1: Pallet 2: Spacer 3: Extruded material

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Shimano 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries Co., Ltd. (72) Inventor Kimiyoshi Korekawa 4-5-33 Kitahama, Chuo-ku, Osaka City No. Sumitomo Metal Industries Co., Ltd. (56) References JP-A-53-81517 (JP, A) JP-A-61-187340 (JP, U) JP-A-3-54127 (JP, Y2) (58) Field (Int.Cl. ⁶ , DB name) B28B 11/24 C04B 40/02

Claims (2)

(57) [Claims] 1. Kneading and molding a cement mixture, receiving the molded material on a pallet, stacking the pallet ,
A method of transferring to a curing cabinet for curing under a steam atmosphere and curing the molding material to obtain a cement building material.Before the transfer to the curing cabinet, the molding material loaded on a pallet and stacked is stacked. The cement building material is characterized in that the moisture does not enter and exit from the surrounding curing atmosphere, and that the barrier between the curing atmosphere and the surface of the molding material does not come into direct contact with each other. Production method. 2. The method according to claim 1, wherein the curing temperature is 40 ° C. or higher.