JPH0242784B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a fiber-reinforced gypsum-based cured product, and more specifically, for use as an interior/exterior material in a building material with excellent fire resistance, dimensional accuracy, flexibility, and bendability. The present invention relates to a method for manufacturing a fiber-reinforced gypsum-based cured product. [Prior Art] A method for manufacturing a fiber-reinforced plaster-based hardened body was developed and registered as an interior and exterior material for buildings from the standpoint of resource and energy conservation (Japanese Patent Publication No. 1983-46985). The method for producing this fiber-reinforced plaster-based cured product is as follows:
The main ingredients are dihydrate and fine slag, and an alkaline substance is added as a stimulant for the fine slag.
Further, an aluminum sulfate-containing substance is added as a reaction accelerator, at least one or two reinforcing fibers selected from asbestos, glass fiber, carbon fiber, bulb, synthetic fiber, etc. are mixed, and if necessary, lightweight aggregate is added. By mixing, cylinder paper making method, extrusion molding method,
Alternatively, it is manufactured by a method such as a molding method. [Problems to be Solved by the Invention] The method for producing a fiber-reinforced gypsum-based hardened body disclosed in the above-mentioned Japanese Patent Publication No. 55-46985 uses dihydrate gypsum and fine slag as the main components, and the hardened crystalline body contains ethrin guide. Consists of crystals and calcium silicate hydrate. This Etrin guide is a needle-shaped crystal, but the crystals obtained are small, so attempts were made to grow the needle-shaped crystal to a larger size, but the progress did not go as expected. Therefore, products made of fiber-reinforced gypsum cured products have advantages such as high strength, quick hardening, water resistance, weather resistance, and excellent workability, as well as being inexpensive. On the other hand, like general noncombustible materials, it was hard and brittle, far from the properties of lumber, and there were problems in processing and handling. The present inventors have studied the above-mentioned problems, and by replacing dihydrate gypsum with calcined gypsum and adding a setting retarder in the above manufacturing method, the condensation of calcined gypsum can be prevented by hydrolysis of slag. We have discovered that by adjusting the matrix so that it is longer than that, it is possible to generate large needle-like crystals that are completely different from conventional matrices. As a result of extensive research in order to add flexibility to the conventional invention and to provide it with highly flexible characteristics, the present invention has been completed. Therefore, it is an object of the present invention to have flexibility and
The object of the present invention is to provide a method for producing a fiber-reinforced plaster-based hardened body that is highly flexible, easy to process and handle, and has properties close to those of wood. [Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention mixed slag and slag in a certain ratio, and added an alkaline substance, an aluminum sulfate-containing substance, and a setting retarder. After mixing, a technical measure was taken in which fibers and water were added and mixed, and lightweight aggregate was further mixed, molded, and then cured under moist heat. That is, in the manufacturing method of the present invention, calcined plaster and slag are mixed in a weight ratio of 2:8 to 8:2, and the resulting mixture is added with an alkaline substance,
After adding and mixing the aluminum sulfate-containing substance and the set retarder, adding and mixing the fibers and water, and further mixing the lightweight aggregate, shaping the resulting mixture,
This is a method for producing a fiber-reinforced gypsum-based cured product, which is characterized in that it is then subjected to moist heat curing. In this production method, as additive substances, (a) an alkaline substance, an aluminum sulfate-containing substance, and a setting retarder are added in the following proportions:
It should be 0.1 to 5% by weight based on the slag mixture. (b) The mixing ratio of fibers is 5 to 30% based on the mixture of plaster and slag, (c) The lightweight aggregate is 1 to 25% by weight based on the mixture, (d) Moist heat. It is preferable to cure at a temperature of 90°C or lower and 400°C/hour or higher. The calcined plaster used here is one or a mixture of β-type plaster and soluble anhydrous plaster. Since these calcined plasters set quickly, it is necessary to select a setting retarder to prolong the setting time and control crystallization. As the setting retarder, one or more of alkali citrate, peptone, gelatin, and amino acid derivatives are used. The slag may have a specific surface area of 3000 cm ² /g or more, and glassy blast furnace slag is preferred, but other amorphous electric furnace slags can also be used. Examples of alkaline substances include caustic soda and caustic potash, alkali metal salts such as sodium sulfate and potassium sulfate, alkaline earth metal salts such as slaked lime, and hydraulic substances such as boltland cement, blast furnace cement, fly ash cement, and alumina. Contains cement and other mixed cements, etc., and the amount added is based on the above main raw materials.
0.1-10% by weight, preferably 1.5-6.0% by weight. However, if the hydraulic material does not contain enough alumina raw material for the growth of ettringite, supplement it. Examples of aluminum sulfate-containing substances include aluminum sulfate, preferably anhydrous aluminum sulfate, sodium alum, and potassium alum, and the amount added is 0.1 to 5% by weight, preferably 0.5 to 2.0% by weight based on the main raw material. Weight%. The aluminum sulfate-containing substance can be added simultaneously with the alkaline substance or separately. If the amount of these additives added is below each of the lower limits mentioned above, the effect of addition will be small, and if it is more than the upper limit, the strength of the resulting cured product will be reduced. Inorganic fibers and organic fibers can be used as reinforcing fibers, and the former include, for example, asbestos (including chrysotile and amosite), rock wool, glass fiber (including alkali-free glass, low-alkali glass, and alkali-resistant glass), and steel. These include fibers (including iron-based and stainless steel), ballastonite, and mica flakes; the latter include carbon fibers, synthetic aramid fibers, vinylon fibers, acrylic fibers, polypropylene fibers, nylon fibers, pulp fibers, and natural fibers. Contains vegetable fiber. The length of these fibers can be appropriately selected in consideration of workability, workability of the cured product, bending strength, etc., but the fiber length is 0.5 to 50 mm, preferably 2 to 10 mm.
It is possible to add one or more types of these fibers, such as asbestos and glass fiber,
Asbestos-polypropylene fiber, etc. Addition of reinforcing fibers not only helps the molding and shape retention of the cured product, but also improves the physical properties of the cured product, especially its bending strength and toughness. The amount added is 15~15% to the main raw material.
30% by weight, preferably 10-25% by weight. If the amount added exceeds 30% by weight, the bending strength will decrease and the shape retention will be poor. Inorganic and organic lightweight materials can be used as the lightweight materials. Examples of the inorganic lightweight materials include shirasu balloons, perlite, foamed lightweight aggregate, and dihydric zeolite, and examples of the organic lightweight materials include wood chips and foamed materials. Styrene foam is effective. Also, when the purpose is to improve weather resistance, calcium carbonate, which is used in cement concrete, is used. The amount of lightweight material added is 1 to the main component.
-15% by weight, preferably 4-8% by weight. Adding lightweight materials reduces the bulk specific gravity of the cured product, so
When the amount added exceeds 15% by weight, the physical properties generally deteriorate, and when the amount added is less than 1% by weight, the effect of the addition is small. Next, the molding method is not limited and any known method can be used. For example, pouring method, pressure molding method, extrusion molding method,
Various types of cement and finely powdered calcium carbonate can be used in combination with the papermaking method and during molding. The amount of water added to the raw material for preparing the cured product varies depending on the molding method, and the amount of water suitable for the molding method can be appropriately selected. The hardened product obtained by the present invention is essentially composed of calcium oxide (CaO) and aluminum oxide (Al ₂ O ₃ ) in slag, which are the main raw materials, and dihydrate gypsum (CaSO ₄ 2H) produced from calcined gypsum. Etrin guide (3CaO_・Al ₂ O ₃・
3CaSO ₄ 31~32H ₂ O), needle-shaped dihydrate crystals generated from calcined plaster, and calcium silicate hydrate surrounding these crystals, and the high strength of this hardened product is This is ensured by the above-mentioned hydrated dihydrate and Ettrin guide at the early age, and by the latent hydraulic properties of the slag at the long age. In addition, when increasing the amount of Ettrin guide produced in a short period of time, an aluminum hydroxide-containing substance such as red mud can be mixed. For curing of the cured product, moist heat curing is performed at a temperature of 90°C or lower and 400°C/hour or higher. When the moist heat temperature exceeds 90℃, dehydration of dihydrate gypsum and decomposition of the generated etrin guide occur. Temperatures above 400°C/hour cause hydrolysis of the slag, which is necessary to produce the various crystals and gel substances mentioned above. In the summer, it may be cured at room temperature, but preferably at temperatures above 2000°C/hour. The effect of adding the above-mentioned alkaline substances and aluminum sulfate-containing substances is that these additives synergistically promote the formation of ettringite, and the formation of ettringite gives the cured product of the present invention high strength at the initial stage, i.e. It imparts quick hardening properties and water resistance. Therefore, the above-mentioned cured product of the present invention has excellent tensile strength, softness, flexibility, and bendability due to the excellent effects of the large dihydrate gypsum grown in the matrix and the acicular crystals of the ettrin guide. It shows the characteristics. [Function] The present invention was completed as a result of research into the flexibility of fiber-reinforced gypsum cured molded articles, focusing on the matrix thereof. The inorganic matrix of the fiber-reinforced gypsum-based hardened product is mainly composed of ettringite, which is a large needle-shaped crystal that has grown, gypsum dihydrate, and calcium silicate hydrate. Most of the dihydrate gypsum produced is needle-shaped crystals, and by growing these crystals larger, the bending strength becomes higher and the amount of deflection becomes larger. This is because the hydrolysis of fine slag begins, reacts with dihydrate, precipitates ettringite crystals, and grows needle-shaped crystals, while hydrolysis of the slag produces calcium silicate gel. However, at this point, if the setting retarder is used to make the calcined gypsum begin to set, needle-shaped crystals of dihydrate gypsum will begin to precipitate from the calcined gypsum at the same time, and these needle-shaped crystals will grow larger. At the same time, the acicular crystals of ettringite also grow large. Therefore, it is preferable that the weight ratio of calcined gypsum and slag be within the range of 2:8 to 8:2.If the weight ratio of calcined gypsum is less than 2, the precipitation of needle-like crystals of dihydrate gypsum is insufficient. However, these needle-like crystals do not grow large. Moreover, if the calcined ecstasy is more than 8, the precipitation of ettringite crystals is small, and the growth of these needle-like crystals is not carried out sufficiently. Figure 1 schematically shows the crystalline state seen under a microscope with a magnification of approximately 50 times. Ettringite 2
The needle-like crystals of 4 and the needle-like crystals of calcined stone hydrate (dihydrate) 4 are intermingled and growing large. [Examples] Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 Main raw materials, auxiliary raw materials, and additives were blended according to the formulations shown in Table 1, No. 1 to No. 8, and water was added and mixed to form a slurry, which was then subjected to a cylinder-type papermaking method. The material was then rolled up, laminated on a making roll to a thickness of 6 mm, and then cut and developed to obtain a green sheet. This raw sheet was steam-cured at 60° C. for 24 hours, then naturally cured for 7 days, and dried to obtain a cured plaster-based material of an example of the present invention. Table 1 also shows Comparative Examples No. 5 to No. 8 manufactured by blending according to the conventional method. Table 1 also shows these physical property values. The lightweight material in the table is pearlite, the additives are A: slaked lime, and B:
is aluminum sulfate and C is a sodium citrate set retarder. As compared to the comparative example, the bending strength and deflection during drying of the example were improved, and the rate of change in length was reduced. In addition, the bending strength and deflection when water is absorbed are improved, and when used as a building material, it becomes easier to construct corners etc. with a slight amount of moisture.

[Table] Example 2 The main raw materials, auxiliary raw materials, and additives were blended according to the formulations shown in Table 2 No. 1 to No. 8, and the (Example 2) of the present invention was prepared under the same conditions as Example 1. A cured plaster-based product was obtained. Table 2 also shows comparative examples No. 12, No. 16, No. 19, and No. 21, which were manufactured using a conventional method. Table 2 shows the physical properties of this.The light weight agent in the table is perlite, the additives are _A1 is boltland cement, _A2 is blast furnace cement, _A3 is alumina cement, and _A4 is flyass cement. B is aluminum sulfate and C is sodium citrate. In comparison with the comparative example, the example has improved deflection, the rate of change in length is particularly reduced, and the bending strength decreases little when water is absorbed, resulting in a very large deflection.

【table】

[Table] [Effects of the Invention] The present invention improves the conventional high strength, water and weather resistance by forming large acicular crystals of dihydrate and ettringite in the matrix of a fiber-reinforced gypsum-based hardened molded product. It is a material that is highly flexible and has excellent workability, and is also made into a molded product that is highly flexible, flexible, and curved.It greatly contributes to its adaptability as a building material, especially in the formation of curved surfaces at corners. It is. Further, the cured product of the present invention has excellent properties when it is used as a building material and is bonded by being slightly moistened and flexed. The manufacturing method of the present invention makes it possible to rationally manufacture the molded article at low cost. Therefore, the industrial value of the present invention is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a schematic view of the matrix of the cured gypsum-based material of the present invention, magnified approximately 50 times. 1...Calcium silicate hydrate, 2...Large-grown needle-like crystals of ettringite, 3...
Large-grown needle-shaped crystals of dihydrate, 4...
Hydrate of calcined gypsum (acicular crystals of dihydrated gypsum).

Claims (1)

[Claims] 1. Mix calcined plaster and slag in a weight ratio of 2:8 to 8:2, add and mix an alkaline substance, an aluminum sulfate-containing substance, and a setting retarder to the resulting mixture, then add fibers and water. 1. A method for producing a fiber-reinforced gypsum-based cured product, which comprises: mixing the fibers, and further mixing lightweight aggregate, shaping the resulting mixture, and subsequently curing with moist heat.