JPH0248504B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a fiber-reinforced plaster-based cured body, and more specifically to a building material that has excellent fire resistance, dimensional accuracy, flexibility, and bendability, and its use as interior and exterior materials. Regarding the manufacturing method. [Prior Art] A method for manufacturing fiber-reinforced plaster-based hardened materials was developed and registered as interior and exterior materials for buildings from the standpoint of resource and energy conservation (Japanese Patent Publication No. 55-46985).
This method for producing a fiber-reinforced gypsum-based cured product consists of dihydrate gypsum and finely divided slag as the main components, an alkali salt substance as a stimulant for the finely divided slag, and an aluminum sulfate-containing substance as a reaction accelerator. One or two types of reinforcing fibers are selected and mixed from asbestos, glass fiber, carbon fiber, pulp, synthetic fiber, etc., and if necessary, lightweight aggregate is further mixed to form a circular mesh, extrusion molding method, etc. Alternatively, it is manufactured by a method such as a molding method. Furthermore, the present applicants have applied for a fiber-reinforced plaster-based hardened body using plaster containing calcined plaster and slag in Japanese Patent Application No. 60-295324, and a method for producing the same. [Problems to be solved by the invention] Molded products made of fiber-reinforced gypsum cured products such as those disclosed in Japanese Patent Publication No. 55-46985 have high strength, quick hardening, water resistance, weather resistance, and excellent workability. Although it is cheap, it is hard and brittle like other noncombustible materials. In order to impart flexibility to this material, make it easier to process and handle, and approximate the properties of lumber, it is necessary to impart flexibility to the base material itself. Japanese Patent Application No. 60-295324 further improves the above-mentioned previous invention to provide a fiber-reinforced plaster-based cured product having excellent flexibility and flexibility, and a method for producing the same. . A further object of the present invention is to provide a method for producing a fiber-reinforced gypsum cured product having such excellent properties more easily. [Means for solving the problem] As a result of various studies, the present inventors have found that in order to produce such a fiber-reinforced gypsum-based cured product, (1) the weight ratio of dihydrate and calcined gypsum is 1:9
to 9:1 plaster and hydraulic material,
Mix plaster and hydraulic material in a weight ratio of 2:8 to 8:2, (2) add and mix an aluminum sulfate-containing material and a setting retarder to the mixture, and (3) mix fibers and water. A technical measure was taken that featured the addition, mixing, molding, and moist heat curing. In this manufacturing method, as a preferred embodiment, (a) the hydraulic substance is Portland cement, blast furnace cement, flyash cement, alumina cement, or other mixed cement; (b) a substance containing aluminum sulfate or a setting retarder is used; The proportion of each added is 0.1 to 5% by weight based on the mixture of plaster and hydraulic substances; (c) The proportion of fibers added is 5 to 30% based on the mixture of plaster and hydraulic substances; (d) Moist heat curing It is preferable to cure at a temperature of 90°C or lower and 400°C/hour or higher. [Function] The inorganic matrix of the fiber-reinforced gypsum-based hardened product is mainly composed of ettringite, gypsum dihydrate, and calcium silicate hydrate.
Both ettringite and dihydric gypsum produced from calcined gypsum are needle-shaped crystals, and by growing these crystals larger, the bending strength becomes higher and the amount of deflection becomes larger. In the present invention, by using a hydraulic substance such as Portland cement instead of using slag or an alkali salt substance, a fiber-reinforced gypsum-based hardened body with excellent performance can be obtained easily and inexpensively. According to the method of the present invention, hydrolysis of the hydraulic substance begins, and this reacts with gypsum dihydrate to precipitate ettringite crystals and grow into needle-like crystals. Thus, a calcium silicate gel is formed, and at this point,
When the setting retardant is used to make the calcined gypsum begin to set, needle-shaped crystals of dihydrate gypsum begin to precipitate from the calcined gypsum at the same time, and these needle-shaped crystals grow larger. At the same time, the needle-like crystals of ettringite grow large, and the needle-like crystals of ettringite and the needle-like crystals of calcined gypsum hydrate (dihydrate) intermingle and grow large. The calcined plaster used here is one or a mixture of two of β-type hemihydrate plaster and soluble anhydrous plaster. Since these calcined plasters set quickly, it is necessary to select a setting retarder to delay the setting time and control crystallization. As the setting retarder, one or more of alkali citrate, peptone, gelatin, and amino acid derivatives are used. Since needle-shaped crystals of dihydrate plaster are generated and the crystals are grown, calcined plaster is essential for plaster. On the other hand, the presence of gypsum dihydrate is considered from the viewpoint of the formation of ettringite. Therefore, dihydrate and calcined plaster should be 1:9 to 9:1,
Preferably the ratio is 3:7 to 7:3. The hydraulic material used is Portland cement, blast furnace cement, flyash cement, alumina cement, and other mixed cements. However, if sufficient alumina raw material is not included for the growth of ettringite, this is replenished. 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%. If the amount of this additive is below each of the above lower limits, the effect of the addition will be small, and if it is above 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. Fibers (including iron-based and stainless steel), wollastonite, and mica flakes are included, and the latter include carbon fibers, aramid fibers of synthetic chemical fibers, vinylon fibers, acrylic fibers, polypropylene fibers, nylon fibers, pulp fibers, Contains natural plant fibers. The length of these fibers can be appropriately selected in consideration of workability, workability of the cured product, bending strength, etc., but the length of the fibers 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,
These include asbestos and polypropylene fibers. 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 also be poor. When reducing weight, it is possible to use inorganic or organic lightweight materials. Examples of inorganic lightweight materials include shirasu balloons, perlite, foamed lightweight aggregate, and synthetic zeolite, and examples of organic lightweight materials include wood chips, Styrene foam, which is an expandable material, is effective. Also, when the purpose is to improve weather resistance, light sand, which is used in cement concrete, is used. The amount of the lightweight material added is 1 to 25% by weight, preferably 10 to 20% by weight, based on the main component. When a lightweight material is added, the bulk specific gravity of the cured product becomes small, so if the amount added exceeds 25% by weight, the physical properties generally deteriorate, and if 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,
There are papermaking methods. 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 cured product obtained by the present invention essentially contains calcium oxide (CaO), aluminum oxide (Al ₂ O ₃ ), and dihydric acid (CaSO ₄ 2H ₂ O) in the hydraulic material as the main raw material. Ettringite (3CaO・Al ₂ O ₃・3CaSO ₄・31～
32H ₃ O), acicular dihydrate produced from calcined gypsum, calcium silicate hydrate surrounding these crystals, and unreacted surplus dihydrate, and this hardened product The high strength shown by is ensured by the needle-shaped plaster formed from the above-mentioned ettringite and calcined gypsum at the early stage of the timber, and by the hydraulic properties of the hydraulic substance at the long stage of the timber. In addition, when producing ettringite in a short period of time and in large quantities, aluminum hydroxide-containing substances,
For example, 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 generated ettringite occur. Temperatures above 400°C/hour cause hydrolysis of hydraulic substances, which is necessary to produce the various crystals and gel substances mentioned above. In addition, in the summer, it may be cured at room temperature, but preferably at 200°C/hour or higher. The effect of adding the aluminum hydroxide-containing substance and the aluminum sulfate-containing substance is that these additives synergistically promote the production of ettringite, and the production of ettringite gives the cured product of the present invention high strength at the initial stage. That is, it imparts quick hardening properties and water resistance. Therefore, the above-mentioned cured product of the present invention exhibits properties rich in tensile strength, softness, flexibility, and bendability due to the excellent effects of the acicular crystals of gypsum dihydrate in the matrix. [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. According to the formulations shown in Table 1, No. 1 to No. 13, the main raw materials, auxiliary raw materials, and additives are blended, water is added and mixed to form a slurry, and the slurry is made into a paper using the circular mesh method. The material was rolled up, laminated on a making roll to a thickness of 6 mm, and then cut and developed to obtain a green sheet. This green sheet was steam-cured at 60° C. for 24 hours, further 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 Example No. 13, which was manufactured using a conventional method. Table 1 also shows these physical property values. The lightweight material in the table is pearlite, additives A and B are slaked lime,
Aluminum sulfate, amino acid-based setting 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.

〔Effect of the invention〕

The method of the present invention uses a hydraulic substance to form acicular crystals of dihydrate in the matrix of a fiber-reinforced gypsum-based cured molded product, which has high strength, excellent water and weather resistance, excellent workability, and flexibility. This makes it possible to rationally manufacture a molded article with excellent flexibility, flexibility, and bendability at low cost. Further, the cured product produced by the method of the present invention has excellent properties when it is used as a building material and is bonded by being slightly moistened and flexed. Therefore, the industrial value of the present invention is extremely large.

Claims (1)

[Scope of Claims] 1 Gypsum dihydrate and calcined gypsum are mixed in a weight ratio of 1:9 to 9:1, and a hydraulic substance is used in a weight ratio of 2:8 to 9:1. Fiber-reinforced plaster characterized by mixing within the range of 8:2, adding and mixing an aluminum sulfate-containing substance and a setting retarder to the mixture, adding fibers and water, mixing, shaping, and moist heat curing. Method for producing a cured product. 2. The method for producing a fiber-reinforced plaster-based cured body according to claim 1, wherein the hydraulic substance is Portland cement, blast furnace cement, flyash cement, alumina cement, or other mixed cement. 3. The fiber reinforcement according to claim 1, wherein the aluminum sulfate-containing substance and the setting retarder are each added in an amount of 0.1 to 5% by weight based on the mixture of plaster and hydraulic substance. A method for producing a plaster-based cured product. 4. The method for producing a fiber-reinforced plaster-based cured product according to claim 1, wherein the mixing ratio of fibers is 5 to 30% by weight based on the mixture of plaster and hydraulic material. 5. The method for producing a fiber-reinforced plaster-based cured product according to claim 1, wherein the curing is carried out at a moist heat curing temperature of 90° C. or lower and 400° C./hour or higher.