JPH08217561A - Light-weight calcium silicate formed body and its production - Google Patents

Abstract

PURPOSE: To improve the resistance to freezing damage to a formed body by forming the formed body having a specified bulk density, predicted closed cell rate, interlayer strength and average linear surface roughness. CONSTITUTION: A material contg. 15-40wt.% portland cement, 10-20% slaked lime, 10-35% diatomaceous earth and 15-55% high-strength closed hollow balloons such as a fly ash balloon having high contents of active silica and aluminum, having a pozzolana action and having <=200μm diameter is used as the main raw material, and the CaO-to-SiO2 molar ratio is controlled to 0.45-0.80. To the main raw material 5-7% pulp slurry, a reinforcing fiber such as carbon fiber and a thickener such as methylcellulose are added to form a slurry, and the slurry is dehydrated and press-formed. The formed body is allowed to stand for >=24hr, then cured and subjected to a hydrothermal synthesis to obtain a lightweight calcium silicate formed body having 0.4-0.9 bulk density, >=15% predicted closed cell rate shown by the expression (porosity = 1-bulk density/true sp.gr.), >=5kgf/cm<2> interlayer strength and <=10μm average linear surface roughness according to JIS B0601.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight calcium silicate compact obtained by using cement, slaked lime, etc. as a raw material, and a method for producing the same, and is lightweight, nonflammable, frost resistance, surface smoothness and workability. The present invention relates to a material that is excellent and can be widely used for applications such as interior and exterior materials for construction.

[0002]

2. Description of the Related Art Calcium silicate compacts made of cement or the like have been widely used as building materials. A molded article of this type is required to have light weight, workability, surface smoothness, fire resistance, nonflammability, durability, frost damage resistance, water resistance and the like. That is, it is required to reduce the weight in response to the increase in the number of buildings, and at the same time, it is required to have fireproof performance, and due to the diversification of architectural design, it has excellent workability and surface smoothness for painting. Is being sought after in recent years,
And in the case of exterior materials, it can withstand weather and ultraviolet rays,
Performance such as water resistance and frost damage resistance is also required.

In particular, with respect to frost damage resistance, there is a close relationship between the strength of the material, the water absorption or water resistance of the material, and the force that relieves the internally generated stress due to volume expansion when free water in the material is frozen. This is because the expansion of fine cracks due to repeated volume expansion during freezing of free water in building materials and contraction during freezing leads to material collapse.

Therefore, in order to obtain frost resistance, the surface of the material is treated to be water resistant so that the material itself does not absorb water, and bubbles in the material are controlled to prevent crack propagation in the material. Measures have been taken. However, there are very few that satisfy all of weight reduction, frost resistance, workability, surface smoothness, nonflammability, and the like.

This kind of calcium silicate compact is generally used as a raw material in a hydraulic cement such as Portland cement, a siliceous source such as silica stone, and if necessary, a lightweight aggregate,
Reinforcing fibers are added. However, there are the following problems regarding the lightweight aggregate. Most of the inorganic lightweight aggregates such as perlite and shirasu balloon that have been used conventionally are
The mechanical strength is weak, and most of them are crushed during mixing and molding, and it is difficult to exert their effects. Furthermore, many of these lightweight aggregates are not hollow closed type, and many have high water absorption rate, so the water absorption rate of the molded body increases as the usage amount of these lightweight aggregates increases, and, Since the matrix strength of the material was also small, it was inferior in terms of frost damage resistance.

On the other hand, organic lightweight aggregates such as foamed styrene have an extremely low bulk specific gravity, and thus float in the raw material slurry, making uniform mixing difficult. In addition, the matrix strength of the material also decreases with the increase in the amount of organic lightweight aggregate used. Furthermore, since the heat resistance is low, it is difficult to cure at high temperature. Therefore, the dimensional change is large, the production cycle time is long, and the heat resistance The problems of sex and incombustibility have also remained.

[0007]

As described above, the conventional calcium silicate compact has various problems.
The present invention is to solve the above-mentioned problems, while being lightweight, it has a high matrix strength, a low water absorption rate, excellent frost damage resistance, and further has surface smoothness and nonflammability. It is intended to provide a calcium compact.

[0008]

In the calcium silicate compact, factors affecting the freezing damage are, as described above, the matrix strength and the water absorption or water resistance.
It is a force to relieve internally generated stress due to volume expansion when free water is frozen. That is, by reducing the amount of free water that is a source of generating internal stress in the material, increasing the amount of closed cells that relaxes the pressure when the free water expands, and further increasing the matrix strength, the material itself It is possible to improve frost damage resistance. Further, the building material is naturally required to have a certain degree of hardness, and when the surface treatment such as painting is taken into consideration, the smoothness of the surface is also required.

The lightweight calcium silicate compact of the present invention has a bulk specific gravity of 0.4 to 0.9, a predicted closed cell ratio of 15% or more as shown in the following formula (1),

[0010]

[Equation 2]

The interlayer strength is 5 kgf / cm ² or more, and the average line surface roughness according to JIS standard B0601 is 10 or more.
μm or less. (Claim 1)

Therefore, this calcium silicate compact is
Lightweight as building material, easy to process, fire resistant, non-combustible,
It can be said to be an extremely excellent material in terms of durability, frost resistance and water resistance. That is, if the bulk density is less than 0.4,
Since the matrix strength is insufficient, the frost damage resistance is inferior, and when the bulk specific gravity is more than 0.9, the matrix becomes hard and the workability deteriorates, and the weight reduction is also inferior. If the interlaminar strength is less than 5 kgf / cm ² , the matrix strength will be insufficient and the frost resistance will be poor. And
If the predicted closed cell rate is less than 15%, the water absorption rate becomes high, and the ability to relieve the expansion pressure during freezing of free water is insufficient.

Here, the predicted closed cell rate shown in the above equation (1) is derived from the following equation (2),
The formula (2) is the water absorption rate in the asbestos slate of JIS standard A5403, and the water absorption rate in the material is calculated from the water absorption rate. The ratio of voids that do not penetrate is calculated, and this non-water-immersed void ratio is divided by the total void ratio to obtain the predicted closed cell ratio. Therefore, this predicted closed cell rate is an index that simultaneously indicates the amount of free water, which is an important factor of freeze-thaw resistance, and the force that relieves the expansion pressure when free water is frozen. In the above formula (1), the specific gravity of water is 1.

[0014]

(Equation 3)

Further, when the average line surface roughness is larger than 10 μm, the smoothness of the surface is inferior, the appearance is bad, and the coating material coating is adversely affected.

The above-mentioned lightweight calcium silicate compact of the present invention can be produced by the following manufacturing method.
That is, 15 to 40% by weight of Portland cement,
The main raw material is 10 to 20% by weight of slaked lime, 10 to 35% by weight of diatomaceous earth, 15 to 55% by weight of a high-strength hollow closed type balloon having a pozzolanic action and having a particle size of 200 μm or less, which contains a large amount of activated silica and aluminum. , More CaO
By mixing the raw materials prepared by adjusting the molar ratio of / SiO ₂ to 0.45 to 0.80 by wet mixing, forming the obtained raw material slurry, and hydrothermally synthesizing this formed body in an autoclave,
can get. (Claim 2) Moreover, in the above-mentioned manufacturing method, 5 to 5 pulp is used as a raw material.
It is possible to add 7% by weight (claim 3) or to add alkali resistant reinforcing fibers to the raw material (claim 4).

In the above-mentioned manufacturing method, the CaO / SiO ₂ molar ratio of the raw materials excluding pulp, reinforcing fibers, etc. is 0.4.
5 to 0.80 is desirable. If it is out of this range, the matrix strength is lowered, so that the frost damage resistance, the bending strength and the interlayer strength are lowered.

In the method for producing a lightweight calcium silicate compact of the present invention, diatomaceous earth and a high-strength hollow closed balloon are mainly used as the siliceous source. Among them, the high-strength hollow closed balloon used is one containing a large amount of activated silica and aluminum and having a pozzolanic action. For example, as the chemical components, those containing 50% or more of SiO ₂ and 30% or more of Al ₂ O ₃ are used. Then, they are eluted during the hydrothermal synthesis and easily stabilize the tobermorite formed in the molded body. In addition, since this balloon is required to have an action of forming independent bubbles (not continuous bubbles) in the molded body, it is not appropriate that all are eluted during the initial stage of hydrothermal synthesis. It must have sufficient strength to withstand the pressure during mixing and molding.

The use of this high-strength hollow closed-type balloon has the purpose of improving frost resistance. As mentioned above, the factors that cause frost damage are increased free water (increased water absorption),
Insufficient matrix strength, and further, insufficient amount of independent bubbles for buffering expansion pressure during freezing of water, etc. are raised from the material standpoint. The use of this balloon can alleviate the above-mentioned problems. Since the balloon itself is a hollow closed type, the water absorption rate decreases, the number of independent bubbles increases, and the pozzolanic reaction produces stable tobermorite,
The matrix strength increases. Therefore, it can greatly contribute to frost damage resistance. In addition, the tobermorite (which has a large amount of Si → Al substitution) generated at this time has large crystals, and the action of reducing the specific surface area of the material itself can also be expected for this balloon. For this reason, the amount of dimensional change during water absorption also shows good results.

The high-strength hollow closed balloon used here is required to contain a large amount of activated silica and aluminum to have a pozzolanic reaction, and a fly ash balloon is one that satisfies this. Among them, ceramic fly ash balloons, such as Chichibu Onoda Co., Ltd.'s product name "Microcells",
It is particularly desirable because it has a high strength and a high Al ₂ O ₃ content.

The "microcells" are fly ash balloons produced in Australia, which are separated from fly ash generated in a coal-fired power plant that uses coal with an ash content of about 30% or more. ₂ is 6
A little less than 0%, Al ₂ O ₃ is a little over 38%, and in addition to this, Fe ₂ O 3
₃ is about 0.4%, CaO is about 0.2%, TiO ₂ is about 1%, and the phase composition is about 55% for mullite and about 45% for glass, and it can be said that it is a ceramic material. In addition to this, there are fly ash balloons from the United Kingdom, the United States, China, etc., which can also be used,
The Australian "microcells" mentioned above,
Different chemical composition and low strength. For example, British fly ash balloons have a chemical composition of SiO ₂ ,
Fe ₂ O ₃ is relatively large in addition to Al ₂ O ₃ , and Na ₂
It also contains O and Ka ₂ O, and has low strength.

The amount of this high-strength hollow closed balloon used is 15 to 55% by weight of the raw material excluding pulp, reinforcing fibers and the like.
Is desirable. If it is 15% by weight or less, the amount of closed cells is small (the predicted closed cell rate becomes 15% or less), and the frost damage resistance is insufficient. Further, when the content is 55% by weight or more, it is difficult to secure a CaO / SiO ₂ molar ratio of 0.45 or more as a raw material in view of the composition.

The use of diatomaceous earth has the following effects. The high-strength hollow closed-type balloon described above has many glassy substances and has a low Si elution rate during hydrothermal synthesis. In addition, Al ₂
Since the content of SiO ₂ is relatively low due to the presence of O ₃ , if the silica is relied solely on the balloon, the silica will be absolutely insufficient. By supplementing this deficiency with the amount of Si eluted from diatomaceous earth and performing hydrothermal synthesis without leaving free lime, the compactness of the base material can be improved. That is, the smoothness of the finish in the final product can be improved.

Further, since diatomaceous earth has water absorbability, it is possible to improve the shape-retaining property of the formed body when forming the raw material slurry. The amount of diatomaceous earth used is preferably 10 to 35% by weight of the raw materials excluding pulp and reinforcing fibers. If the amount used is more than 35% by weight, an excessive amount of calcium silicate mineral (tobermorite) is produced, so that the final product becomes hard, the workability deteriorates, and the bending strength also decreases. On the other hand, if it is less than 10% by weight, the pressure during molding becomes extremely large, and it is difficult to secure the shape retention.

In the production method of the present invention, diatomaceous earth and a strong hollow closed type balloon are mainly used as the siliceous source, but other siliceous sources such as fly ash can be used as long as they do not affect the product. , Silica sand, silica stone, etc. can be used together.

In the production method of the present invention, Portland cement and slaked lime are mainly used as the calcium source.

The purpose of using Portland cement is as follows. In the production method of the present invention, it is preferable that after forming the raw material slurry, the formed body is allowed to stand in a room for 24 hours or more and then hydrothermally synthesized in an autoclave. When the molded body is hydrothermally synthesized immediately after molding, the molded body expands and cracks occur between the molded layers,
You lose the precision of the final product. Therefore, after molding,
It is necessary to raise the strength of the molded body by performing the synthesis to some extent by leaving it in the room for 24 hours or more.
Portland cement is required for this synthesis.

From this, the amount of cement used is
15-40% by weight of the raw material excluding pulp, reinforcing fibers, etc. is desirable. If it is less than 15% by weight, the strength of the molded article in the autoclave is insufficient, and if it is more than 40% by weight, it is difficult to secure a CaO / SiO ₂ molar ratio of 0.80 or less due to its composition.

The action of slaked lime supplements the lack of calcium source than Portland cement and promotes the pozzolanic reaction. The amount used is preferably 10 to 20% by weight of the raw materials excluding pulp, reinforcing fibers and the like. 10% by weight
If the amount is less than the above, the calcium source will be insufficient, it will be difficult to secure a CaO / SiO ₂ molar ratio of 0.45 or less, and the strength development of the green plate before curing in the autoclave and the compactness of the product will deteriorate.
If it is more than 20% by weight, the amount of cement used decreases,
The strength of the raw plate is small.

In the production method of the present invention, although Portland cement and slaked lime are mainly used as the calcium source, other calcium-based sources such as slag can be used in combination as long as it does not affect the product. .

As the reinforcing fiber to be mixed with the raw material,
Any fiber that is strong against alkali can be used. For example, inorganic fibers such as alkali-resistant glass fiber, carbon fiber and rock wool fiber, and organic fibers such as acrylic fiber and polypropylene fiber can be used.
In addition, since pulp contributes to prevent floating of balloons during wet mixing of raw materials, it is desirable to use the pulp, and the amount of this pulp used is desirably 5% to 7%. If it is less than 5%, the workability is deteriorated, and if it is more than 7%, the incombustibility is lowered.

In addition, various admixture materials and additives such as thickeners and defoaming agents can be blended according to a conventional method for producing this type of calcium silicate compact. For example, a thickener is widely used for the purpose of preventing the material separation of the raw material slurry, but a common thickener can be used, for example, methyl cellulose, polyethylene oxide, hydroxyethyl ell cellulose, Examples include carboxymethyl cellulose and sodium polyacrylate.

A raw material slurry is prepared from the above-mentioned raw materials, and if necessary, pulp and reinforcing fibers are added thereto, the raw material slurry is molded, and the molded body is aged by an autoclave to form a lightweight calcium silicate molding. You can get the body. Since the lightweight calcium silicate compact manufactured by the above-mentioned method contains aluminumnium as a raw material, tobermorite, which is a stable mineral, is used as a matrix.

The lightweight calcium silicate compact of the present invention is a conventional calcium silicate compact (for example, JP-A-4-30504).
Compared with the calcium silicate plate shown in No. 1), it is lighter in weight, yet has excellent frost damage resistance, and has the same or better strength in terms of bending strength, etc., and has workability (eg cutting, nailing, screwing). Is also excellent.

[0035]

EXAMPLES Next, more detailed description will be given with reference to examples, but the present invention is not limited to the examples shown below. First, a slurry having a pulp solid concentration of 3% is prepared in a pulper. In this slurry, Portland cement, slaked lime, diatomaceous earth, silica stone, high-strength hollow closed-type balloon (with a blending ratio of Examples 1 to 7 shown in Table 1 and a blending ratio of Comparative Examples 1 to 8 shown in Table 2 ( Microcells) and perlite are added and mixed with a mixer, and then the raw material slurry is passed through a free pulverizer, and further, glass fibers are mixed with the raw material slurry in an omni mixer.

Then, 0.4 parts by weight of methyl cellulose was added to the raw material slurry with respect to its solid content, and dehydration press molding was carried out at a predetermined pressing pressure to obtain a molded body.
After being left in the room for 20 hours, the molded body was cured by an autoclave (180 ° C., 10 atmospheric pressure, 12 hours) and then dried at 105 ° C. for 24 hours to obtain a plate-shaped calcium silicate molded body.

[0037]

[Table 1]

[0038]

[Table 2]

The raw materials used here are as follows. Portland Cement Chichibu Onoda Co., Ltd. Ordinary Boltland Cement Slaked lime Kotegawa Sangyo Co., Ltd. High-strength hollow closed balloon Chichibu Onoda Co., Ltd. Microcells (SLG) Perlite Fuyolite Co., Ltd. FL1 Diatomite Shirayama Industry Co., Ltd. Radiolite SPF Silica stone Seto Ceramics Co., Ltd. Toane silica stone (63 μm or less) Methyl cellulose Shin-Etsu Chemical Co., Ltd. High-Metroze Alkali-resistant glass fiber Nippon Electric Glass Co., Ltd. Fiber length 13 mm, 11 μ Pulp Canadian LBKP

Then, the following tests and evaluations were performed on the product and the raw plate before autoclaving. The results are shown in Table 1.
And shown in Table 2. (1) Dimensional stability during water absorption: JIS A5403 Asbestos slate Length change rate test due to water absorption (2) Nailing test: 2 cm at 1 cm from the edge of the plate
Seven pieces of 2.3 mm in diameter and 50 mm in length were struck every other time, and the condition of the plate was evaluated as follows. Good One nail does not bend, and boards at 1 to 3 places crack. The nails bend a little, and the board also cracks at one to three places. Impossible nails are hard to hit. Or the board is broken at 4 or more places. (3) Average line surface roughness: The surface after the surface has been smoothed by a router is obtained from JISB0601 surface roughness standard. (4) Freeze-thaw test: JIS A1435 Freeze-thaw resistance test method for building exterior materials. The appearance was observed. (5) Surface rubber hardness (green board): JIS 6301 Vulcanized rubber physical test (6) 〃 (Product): ASTM D2240 TEST METHOD FOR RUBBER PROPERTY DUROMETAER HARDNESS

Examples 1 to 3 mainly show the difference in bulk specific gravity. Those with high bulk specific gravity have high matrix strength (bending strength, interlayer strength),
Since the water absorption rate is low, the frost damage resistance is high even if the predicted closed air bubble ratio is somewhat low. Further, as the bulk specific gravity decreases, the frost damage resistance deteriorates. However, a material having a large bulk density is inferior in the nailing test because the material becomes hard. Here, the calculation of the predicted closed cell rate will be specifically described by taking the third embodiment as an example. By inserting the following value into the above equation (1), the predicted closed cell rate can be calculated as in the following equation (3). Bulk specific gravity = 0.69 g / cm ³ True specific gravity = 2.5 g / cm ³ (Pycnometer) Water absorption rate = 78.2% (JIS 5403 Water absorption rate test)

[0042]

[Equation 4]

In addition, in Examples 3 to 7 and Comparative Examples 1 to 4, the CaO / SiO ₂ molar ratio of the raw material and the amount of diatomaceous earth in the raw material were compared. CaO
It can be seen that when the / SiO ₂ molar ratio becomes too high, the bending strength also decreases when compared with the same bulk specific gravity.
Further, it can be seen that, when the amount of diatomaceous earth used is high, the nailing test, frost damage resistance, and dimensional stability during water absorption deteriorate. On the contrary, when the CaO / SiO ₂ molar ratio is low and the amount of diatomaceous earth used is low, the density is poor, the average line surface roughness is large, and the surface smoothness is poor.

Comparative Examples 5 and 6 are examples in which Portland cement was not used at all. This is a slightly different manufacturing method from the above-mentioned Examples and other comparative examples, adding an appropriate amount of water to a part or all of slaked lime and diatomaceous earth, heating and gelling, and in the gel slurry, silica stone and the remaining diatomaceous earth. Alternatively, microcells, pulp, and reinforcing fibers are added, mixed, molded, and synthesized by an autoclave (180
(° C., 10 atm, 3 hours) and dried. The tobermorite-based artificial wood currently on the market is roughly produced by such a method.

In Comparative Example 5, since the predicted closed cell rate is almost 0, it can be seen that there is almost no frost damage resistance. Comparative Example 6 is expected to be excellent in frost damage resistance because of the high closed cell ratio, but it is understood that since pozzolanic reaction rarely occurs, it is inferior in surface smoothness due to compactness. In addition, since the strength of the raw plate before synthesis is weak, it expands during hydrothermal synthesis and becomes dense. For this reason, in the freeze-thaw test, the strength was significantly reduced by the first absorption of water, and the test was impossible.

[0046]

The lightweight calcium silicate compact of the present invention comprises:
Properties suitable for use in interior and exterior materials for construction, that is,
It is a material that is lightweight, yet has excellent nonflammability, frost damage resistance, and surface smoothness.

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Claims (4)

[Claims] 1. A bulk specific gravity of 0.4 to 0.9, a predicted closed cell ratio shown in the following formula (1) of 15% or more, and A lightweight calcium silicate compact having an interlaminar strength of 5 kgf / cm ² or more and an average line surface roughness of 10 μm or less according to JIS B0601. 2. A high-strength hollow having a particle size of not more than 200 μm and having a pozzolanic effect, containing 15 to 40% by weight of Portland cement, 10 to 20% by weight of slaked lime, 10 to 35% by weight of diatomaceous earth, and containing a large amount of activated silica and aluminum. Closed type balloons are mainly composed of 15-55% by weight and CaO /
A lightweight calcium silicate characterized by wet-mixing raw materials adjusted to have a SiO ₂ molar ratio of 0.45 to 0.80, shaping the resulting raw material slurry, and hydrothermally synthesizing this shaped body in an autoclave. Method for manufacturing molded body. 3. The method for producing a lightweight calcium silicate compact according to claim 2, wherein 5 to 7% by weight of pulp is added to the raw material. 4. At least one kind of inorganic fiber such as alkali-resistant glass fiber and carbon fiber and organic fiber having alkali resistance such as polypropylene fiber and acrylic fiber are added to the raw material as reinforcing fiber.
Alternatively, the method for producing a lightweight calcium silicate compact according to item 2.