JPS6250439B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a magnesia cement composite. Hardened magnesia cement is dense, has excellent mechanical properties, and is nonflammable, so it is attracting attention as a material that can replace conventional organic synthetic materials in the field of building materials and solve the problem of flammability. has been done. However, on the other hand, it suffers from a lack of water resistance, making it necessary to avoid using it in places with a lot of moisture or humidity, which has the problem of severely limiting its uses. As one method for improving the water resistance of this hardened magnesia cement body, it has been proposed to coat the surface of the hardened body with a water-resistant material. On the other hand, it is already well known that portland cement and alumina cement have excellent water resistance, but since these have poor adhesion to magnesia cement, they easily peel off even if coated. for example,
When the surface of uncured magnesia cement is coated with uncured portland cement and hardened, the portland cement is rapidly set by magnesium chloride etc. that are eluted when the magnesia cement hardens, and as a result, the strength of the hardened portland cement is reduced. Not only does this decrease, but also good adhesion is not achieved at the interface with the hardened magnesia cement. In addition, even if uncured portland cement is laminated and coated on the hardened magnesia cement,
Since the hardening speed of Portland cement is slow, magnesium chloride and the like from the hardened magnesia cement are redissolved in Portland cement, resulting in rapid setting of Portland cement. On the other hand, even if uncured portland cement is rapidly cured by heating it on a hardened magnesia cement and magnesium chloride from magnesia cement is prevented from redissolving into portland cement, the strength of portland cement itself will decrease. Undesirable. The present invention was made to solve the above problems, and while maintaining the excellent mechanical strength of magnesia cement and Portland cement,
The object of the present invention is to provide a method for producing a magnesia cement composite in which a hardened portland cement is firmly adhered and coated with a hardened magnesia cement. The method for producing a magnesia cement composite of the present invention includes activated magnesia, magnesium chloride and/or
Or, after heating and curing magnesia cement consisting of magnesium sulfate and water, alumina cement is added for 50 to 840 parts by weight of Portland cement.
40-60 parts by weight, 30-60 parts by weight of gypsum and 2-2 parts of lime
The present invention is characterized in that a water paste of a portland cement blend consisting of 15 parts by weight is laminated and coated on the magnesia cement and cured by heating. As is conventionally known, the magnesia cement composition used in the present invention contains 20 to 60 parts by weight of magnesium chloride or 15 to 100 parts by weight of magnesium sulfate in terms of anhydride per 100 parts by weight of active magnesia. 40 to 150 parts by weight of water is added to this and used as a water paste. When magnesium chloride and magnesium sulfate are used together, the ratio is preferably 0.4 to 5 moles of magnesium chloride per mole of magnesium sulfate, and the total amount is preferably 25 to 75 parts by weight per 100 parts by weight of active magnesia. The Portland cement mixture used in the present invention has the above-described composition, and when the amount of Portland cement blended is less than 50 parts by weight, the long-term strength of the cured coating is insufficient and the heat resistance is also poor. On the other hand, if it exceeds 840 parts by weight, the amounts of alumina cement, gypsum and lime in the formulation will be relatively reduced, resulting in poor thermosetting properties. According to the method of the present invention, by blending the above-mentioned amounts of alumina cement, gypsum, and lime with Portland cement, ettringite crystals are rapidly generated during heat curing, and a large amount of water is absorbed.
It suppresses the elution of magnesium chloride, etc. in magnesia cement, and provides demolding strength. Therefore, if the blending amounts of alumina cement, gypsum, and lime are outside the above range, some of these will remain unreacted or will be hydrated alone, resulting in a decrease in thermosetting properties and magnesia. As the adhesion with cement decreases, the strength of the hardened Portland cement product also decreases. Note that when a large amount of Portland cement is blended, it is not necessarily necessary to separately blend lime because the Portland cement supplies lime for forming ettringite crystals. A water paste is obtained by blending 40 to 150 parts by weight of water per 100 parts by weight of Portland cement into such a Portland cement mixture. In the present invention, in order to improve the adhesion between magnesia cement and a cured Portland cement mixture, each cement mixture desirably contains 2.5 to 30 parts by weight of rubber latex per 100 parts by weight. It is desirable to ensure good adhesion between portland cement and magnesia cement due to the relative reduction in the amount of alumina cement, gypsum and lime, especially when the amount of portland cement in the portland cement formulation is high. . If desired, rubber latex may be included only in the Portland cement formulation. Furthermore, in the present invention, the magnesia cement compound and the Portland cement compound are cured by adjusting the curing speed at the time of curing to suppress rapid curing, and to prevent the viscosity from becoming too high when adding and mixing water. It is preferable to contain a regulator. In the case of a magnesia cement compound, the blending amount is 0.01 to 10 parts by weight per 100 parts by weight of active magnesia;
For portland cement formulations, 0.5 to 3 parts by weight per 100 parts by weight of alumina cement, gypsum and lime are preferred. as needed,
It is also possible to incorporate a hardening modifier into only one of the cement formulations. Hardening modifiers are already known; for example, in magnesia cement, phosphoric acid, condensed phosphoric acids such as hexametaphosphoric acid and pyrophosphoric acid, their salts, boron oxide, etc. are used, and in the case of Portland cement, phosphoric acid, condensed phosphoric acid, etc. Phosphoric acid, salts thereof, organic acids such as citric acid, malic acid, gluconic acid, glutaric acid, and glycolic acid, and alkali metal salts thereof are used. According to the method of the present invention, a water paste of a magnesia cement compound is shaped into a desired shape and cured by heating, and then a water paste of a portland cement compound is laminated and coated to a desired thickness and cured by heating.
A suitable heating temperature is 60 to 100°C. The shaping and heating method is not particularly limited, and any method such as an extrusion method, a drawing method, a filament winding method, etc. may be used. After shaping and curing, a magnesia cement-Portland cement composite hardened body is obtained by curing. In addition, if necessary, a fiber material such as glass fiber may be dispersed and contained as a reinforcing material in the blend of one or both of magnesia cement and Portland cement.
Alternatively, a sheet such as a glass fiber mat may be impregnated with the blended water paste. Furthermore, fillers, aggregates, etc. may be included. As described above, in the method of the present invention, magnesia cement is cured by heating, and then a portland cement blend water paste consisting of portland cement, alumina cement, gypsum and lime is laminated and coated, and then cured by heating. Therefore, as mentioned above,
The Portland cement composition rapidly forms ettringite crystals, absorbs a large amount of water, suppresses the elution of magnesium chloride, etc. from the magnesia cement, and hardens in a short time, allowing the Portland cement to firmly adhere to the magnesia cement. A coated composite is obtained, and the adhesion properties can be further improved by further incorporating rubber latex into each cement formulation. Examples of the present invention are listed below along with comparative examples, but the present invention is not limited to these Examples in any way. Note that parts are parts by weight. Example 1 100 parts of activated magnesia (calcined at 650°C) was mixed with 73 parts of magnesium chloride hexahydrate and sodium tripolyphosphate.
A magnesia cement paste was prepared by mixing it with an aqueous solution consisting of 0.7 parts and 59 parts of water, and this was impregnated into glass fiber chopped strand mat,
It was laminated on the formwork to a thickness of 7 mm. This formwork is 10Kg/cm ²
Pressurize at a pressure of
It was held at this temperature for a minute to cure. For 100 parts of early strength Portland cement, 50 parts of alumina cement, 35 parts of hemihydrate, 5 parts of lime,
To a paste consisting of 0.7 parts of sodium citrate and 93 parts of water, 100 parts of silica sand (No. 7) was added as an aggregate, and further 5 parts of rubber latex were added. This paste was laminated to a thickness of 3 mm on the cured magnesia cement, and was pressed at 10 kg/cm ² and 70° C. for 15 minutes to heat cure. After cooling, it could be removed from the mold without losing its shape, and a composite was obtained. Example 2 100 parts of activated magnesia (calcined at 650°C) was mixed with 50 parts of anhydrous magnesium sulfate, 1 part of hexametaphosphoric acid, and water.
A magnesia cement paste was prepared by mixing with an aqueous solution consisting of 100 parts. This was impregnated into glass fiber chopped strand mat and placed in a formwork to a thickness of 9mm.
The mold was pressed with a force of 10 kg/cm ² and simultaneously heated to 80° C. for 10 minutes to cure. The same Portland cement paste as in Example 1 with a water-cement ratio of 0.45 was coated on the cured magnesia cement to a thickness of 3 mm, and then heated and cured at 70° C. and 10 kg/cm ² for 10 minutes. After cooling, it does not lose its shape,
The composite could be demolded from the formwork. Example 3 Glass roving fibers were soaked in the same magnesia cement paste as in Example 1, and wound into a cylindrical shape using the filament winding method. Next, a glass fiber mat was wound around the fibers. These operations were repeated to make a 10 mm thick cylindrical body. I got it. This cylindrical body is heated to 80℃
After curing by heating for 7 minutes, the same portland cement paste as in Example 1 was coated and the temperature was 70℃.
Heating was performed for 15 minutes to obtain a magnesia cement-Portland cement composite pipe. Example 4 Glass roving fibers and glass mat were impregnated with the same magnesia cement paste as in Example 1,
Roving fibers, matte, and roving fibers were laminated in three layers with a thickness of 6 mm in this order. This was inserted into a drawing mold and continuously pulled out from the mold while heating at 75° C. for 5 minutes. The same Portland cement paste as in Example 1 except that it did not contain silica sand was sprayed onto the above-mentioned hardened body to a thickness of 1.5 mm using a spray gun, and then fed into a heating furnace and heated at 70°C for 10 minutes to continuously heat it. A plate-like composite was obtained. Example 5 100 parts of activated magnesia (calcined at 700°C), 82 parts of magnesium chloride hexahydrate, 5 parts of tribasic magnesium phosphate
After mixing 60 parts of water with 0.5 parts of sodium tripolyphosphate and 0.5 parts of sodium tripolyphosphate, a paste was prepared by adding 3% by volume of glass fiber chops having a length of 25 mm. This was poured into a mold to a thickness of 10 mm, at a pressure of 8 kg/cm ² and a temperature of 80°C.
It was held for 10 minutes to heat and cure. 500 parts of ultra early strength Portland cement, 60 parts of alumina cement, 40 parts of hemihydrate and 2 parts of lime were added to an aqueous solution of 1 part of sodium gluconate dissolved in 314 parts of water, plus 600 parts of silica sand (No. 7) and rubber latex. A paste was prepared by adding 50 parts and 3% by volume of glass fiber chops having a length of 13 mm. This paste was coated on the magnesia cement hardened body, and
Heat to 80℃ for 10 minutes at a pressure of Kg/cm ² to a thickness of 2mm.
A coated cured product was obtained. After demolding, the cured product was cured at room temperature for 28 days, and a 2 kg weight was dropped onto the cured product from a predetermined height to perform an impact test. The results are shown in Table 1.

[Table] Comparative example 100 parts of activated magnesia (calcined at 700°C), 82 parts of magnesium chloride hexahydrate, 0.25 parts of boron oxide, and 60 parts of water
To this, add 3% by volume of glass fiber chops with a length of 25 mm, mix to prepare a paste,
This was heated in a mold to a temperature of 90°C to harden it. Portland cement was mixed with silica sand (No. 7) at a cement ratio of 1.0 and a water-cement ratio of 0.47, and 3% by volume of glass fiber chops with a length of 13 mm was added to prepare Portland cement paste, and this was mixed with the above-mentioned hardened magnesia cement. coated on the surface.
It was cured at room temperature for 28 days to form a 2 mm thick hardened portland cement coating. An impact test was conducted in the same manner as in Example 5, and the results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. Activated magnesia, magnesium chloride and/or
Or after heating and curing a water paste of a magnesia cement mixture consisting of magnesium sulfate, 40 to 60 parts by weight of alumina cement, 30 to 60 parts by weight of gypsum and 2 to 15 parts by weight of coal for 50 to 840 parts by weight of Portland cement. A method for producing a magnesia cement composite, comprising laminating and coating a water paste of a portland cement mixture on the magnesia cement, and curing it by heating. 2. The method for producing a magnesia cement composite according to claim 1, characterized in that the portland cement mixture and/or the magnesia cement mixture contain 2.5 to 30 parts by weight of rubber latex per 100 parts by weight of each mixture.