JPH0826850A - Inorganic plate and its production - Google Patents

Abstract

PURPOSE:To reduce the weight of a cement-based inorganic plate formed through a curing and hardening treatment and containing lightweight aggregates without reduction of mechanical strength by making up this plate from three layers composed of surface layers and an interlayer and making the percentages of dimensional change of both the surface layers almost equal to each other and different from that of the interlayer during the course of curing and hardening. CONSTITUTION:This method for production of inorganic plate can improve mechanical strength since a prestress is generated between the front and back surface layers and the interlayer by dimensional change during the course of curing and hardening process. In this method, occurrence of a warp is scarce since both the front and back surface layers of the inorganic plate exhibit an almost equal dimensional change during the course of curing and hardening process. In addition, during the course of curing and hardening, one of the surface layers, and the interlayer is shrunk whereas the other is swollen. As its result, a high prestress is generated by a synergetic effect of the shrinkage and the swelling and it contributes to improvement of mechanical strength. Specifically, if vermiculite and 5 to 20wt.% pearlite are contained respectively in the surface layers and the interlayer, the interlayer us swollen without fail.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic plate used as a building exterior material, roof tile or interior material, and a method for producing the same.

[0002]

2. Description of the Related Art Since a cement-based inorganic board is disadvantageous in that it is heavy, a cement-based inorganic board improved in this respect has been used as an exterior material or interior material for construction. As a method for reducing the weight, it is common practice to add a lightweight aggregate. In addition to this, there are also foamed concrete such as cellular concrete.

Such an inorganic plate is less likely to be deteriorated in its surface even when exposed to the outside air, and is lightweight, so that it is suitable for use as an outer wall material for construction.

[0004]

However, in the above-mentioned conventional examples, the addition of the lightweight aggregate or the foaming thereof has a drawback of lowering the mechanical strength of the obtained inorganic plate. In particular, foaming causes a remarkable decrease in strength.
Therefore, when such an inorganic plate is processed or applied to an exterior material or the like, it is easily damaged and these operations are difficult to perform.

The present invention has been made to solve the above problems, and an object thereof is to provide a lightweight cement-based inorganic plate without lowering mechanical strength. .

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is a cement-based inorganic plate which includes a lightweight aggregate and is formed by curing and hardening. The surface layer and the central layer are different in dimensional change rate during curing and are substantially equal in the front and back surface layers.

According to a second aspect of the invention, in the first aspect of the invention, the dimensional change rate during curing is such that one of the surface layer and the central layer expands and the other contracts. It is characterized by that.

The invention according to claim 3 is characterized in that, in the invention according to claim 2, it comprises a surface layer containing vermiculite and a central layer containing 5 to 20 wt% of pearlite. .

The invention according to claim 4 is characterized in that a cement-based molded body of three layers in which the composition of the lightweight aggregate is different between the surface layer and the center layer is formed, and the molded body is cured by curing. are doing.

[0010]

According to the first aspect of the present invention, the prestress is generated between the surface layer and the central layer of the inorganic plate obtained by curing and curing due to the change in dimension during curing and curing. Then, this prestress contributes to the improvement of the mechanical strength of the inorganic plate.

Further, in the inorganic plate of the present invention, the dimensional change rates of the front and back surface layers at the time of curing and curing are substantially equal to each other, so that warpage is less likely to occur.

According to the second aspect of the present invention, either one of the surface layer and the central layer contracts and the other expands during curing and a large prestress is obtained by contraction and expansion. It greatly contributes to the improvement of mechanical strength.

According to the third aspect of the invention, the vermiculite added to the surface layer surely shrinks the surface layer during curing and the pearlite added to the center layer 5 to 20 wt% surely expands the center layer. ing.

In the invention according to claim 4, since the lightweight aggregate is mixed in the surface layer and the center layer to form a three-layer cement-based compact, the compact is cured by curing. The dimensions of the surface layer and the center layer change, and prestress occurs.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 by taking an inorganic plate used as an exterior material for construction as an example. FIG. 1 is a schematic view showing the layer structure of the inorganic plate of this example. FIG. 2 is a graph showing the dimensional change during autoclave curing by the additive of the surface layer 1 or the central layer 2.

In FIG. 1, 1 is the front and back surface layers, and 2 is the central layer. The inorganic plate of this embodiment is a cement-based inorganic plate formed by curing and hardening, and is composed of the three layers of the surface layer 1 and the central layer 2 as described above. The dimensional change rate during curing is different between the surface layer 1 and the center layer 2, and the surface layers 1 on the front and back sides are substantially equal to each other.

The procedure for forming the above inorganic plate will be described below. In forming the inorganic plate, first, a mold is filled with a material containing Portland cement as a main component, and press molding is performed to obtain a molded body.

The mold at this time was a box-like one having a size of 40 × 160 mm, and the material for the surface layer 1 was added to the mold.
Fill with a thickness of mm. Furthermore, the material for the central layer 2 is 5
The surface layer 1 filled with a thickness of mm and previously filled therewith 1
Fill the material for 5 mm thick. After that, a molding press is pressed at a pressure of 50 kg / cm ² for 30 seconds to obtain a molded product having a three-layer structure. The molded body thus obtained is steam-cured at 60 ° C. for 20 hours and then at 170 ° C. for 10 hours in an autoclave to obtain an inorganic plate as a product.

In this embodiment, by adjusting the kind and amount of the lightweight aggregate as an additive of the material to be put in the mold, the surface layer 1 and the center layer 2 are respectively aged during curing, especially during autoclave curing. It is possible to improve the mechanical strength by varying the dimensional change rate and causing prestress in the inorganic plate to be the product. Table 1 below
Examples 1 to 5 having such a composition are shown together with Comparative Examples 1 and 2.

[0020]

[Table 1]

The vermiculite or perlite, which is a lightweight aggregate to be added as an additive shown in Table 1, shows the weight percentage with respect to the solid content of the following main ingredients. That is, as a main material, 100 parts of water was added to 100 parts of Portland cement, 100 parts of fly ash, 40 parts of silica stone powder, and 5 parts of pulp, and mixed. In addition, the bending strength of each of the examples or comparative examples shown in Table 1 is 1 mm / m head speed.
Measured in.

As can be seen from the results of the measurement of the bending strength, the formulations of Examples 1 to 5 have the surface layer 1 and the central layer 2
The bending strength is higher than that of Comparative Example 1 in which 10 wt% of the same vermiculite is added. This is because the vermiculite added to the surface layer 1 causes the surface layer 1 to shrink at the time of curing and curing, and the pearlite added to the center layer 2 in an amount of 5 to 20 wt% causes the center layer 2 to expand. This is because a large pre-stress is obtained, which greatly contributes to the improvement of the mechanical strength of the inorganic plate. In addition, Comparative Example 2 is based on the composition of only the main material without addition of perlite and vermiculite, and has a relatively high bending strength, but is different from other Examples 1 to 5 or Comparative Example 1. Although the specific gravity is 1.2 to 1.4, the specific gravity is as high as 1.6, indicating an example of insufficient weight reduction.

FIG. 2 is a graph showing dimensional changes during autoclave curing by additives to the surface layer 1 or the central layer 2. The vertical axis of this graph shows the dimensional change rate, and the horizontal axis shows the weight percentage of pearlite or vermiculie with respect to 100 of the solid content of the main material.

The reason why 5 to 20 wt% pearlite is added to the central layer 2 is that the central layer 2 expands at 5 wt% or more as shown in the graph of FIG. Also, 20
Even if it is added in an amount of wt% or more, it does not expand any more, and the bending strength decreases, which is not preferable. Also, vermiculite shows a substantially constant shrinkage, which is necessary for weight reduction.

As described above, the inorganic plate of this embodiment has a three-layer structure including the surface layer 1 containing vermiculite and the central layer 2 containing 5 to 20 wt% of pearlite. A large amount of prestress is generated, and as a result, it is possible to secure sufficient bending strength and achieve weight reduction. Therefore, it is suitable for applications such as building exterior materials.

As the additive that causes a dimensional change during autoclave curing, not only the above-mentioned perlite or vermiculite but also various other materials can be used. For example, shirasu, shirasu balloon, opal, lapilli, etc. can be used instead of perlite. Further, microsilica or the like can be used instead of vermiculite.

Further, the surface layer 1 does not necessarily have to contract and the center layer 2 needs to expand, and conversely, the surface layer 1 may expand and the center layer 2 may contract. Furthermore, if there is a difference in dimensional change between the surface layer 1 and the central layer 2, prestress can be applied and the mechanical strength can be improved. Therefore, for example, the same pearlite may be added to the surface layer 1 and the central layer 2 in different amounts.

In the above-mentioned procedure for forming the inorganic plate, an example in which a mold is used has been shown, but in addition to this, a slurry-like material is supplied onto the molding belt to a constant thickness, and the surface layer 1 and the center layer are sequentially arranged. 2, a three-layer structure of the surface layer 1 may be formed to obtain a molded body.

[0029]

According to the first aspect of the present invention, the mechanical strength of the obtained inorganic plate can be improved by the prestress generated during the curing and curing of the inorganic plate having the three layers of the surface layer and the central layer. ing.

Therefore, the inorganic plate is compensated for the decrease in mechanical strength due to the weight reduction due to the aggregate. Therefore, when processing or constructing such an inorganic plate as an exterior material, etc., it will not be damaged, it will be easier to perform these works, and it will be a durable one that is not easily damaged by external force even after construction. There is.

Further, the structure is symmetrical in the thickness direction, so that warpage is unlikely to occur.

According to the second aspect of the present invention, since a large prestress can be generated, the mechanical strength of the inorganic plate is greatly improved.

According to the third aspect of the invention, the surface layer contracts reliably and the central layer expands, so that the mechanical strength of the inorganic plate is greatly improved.

In the invention according to claim 4, only the composition of the lightweight aggregate is changed between the surface layer and the center layer, and prestress is obtained at the time of curing and curing, and no other jig or the like is used. By a simple method, a lightweight inorganic plate having mechanical strength can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a layer structure of an inorganic plate in one example of the present invention.

FIG. 2 is a graph showing a dimensional change during autoclave curing by an additive to a surface layer or a central layer of the same inorganic plate.

[Explanation of symbols]

 1 surface layer 2 center layer

Claims (4)

[Claims] 1. A cement-based inorganic plate containing lightweight aggregate, which is formed by curing and curing, and comprises three layers, a surface layer and a center layer, and the dimensional change rate during curing is the surface layer and the center layer. An inorganic plate characterized by being different in layers and being substantially equal in front and back surface layers. 2. The inorganic plate according to claim 1, wherein the dimensional change rate during curing is such that one of the surface layer and the central layer expands and the other contracts. 3. The inorganic plate according to claim 2, which comprises a surface layer containing vermiculite and a central layer containing 5 to 20 wt% of pearlite. 4. A method for producing an inorganic plate, which comprises forming a three-layer cement-based molded product in which the composition of the lightweight aggregate is different between the surface layer and the central layer, and curing the molded product.