JPH0345576A - Production of light-weight cement molding - Google Patents

Abstract

PURPOSE:To obtain a light-weight cement molding having high content of foamed particle of synthetic resin and excellent heat insulating properties by casting cement paste and foamed particles of synthetic resin to a mold having fine pores, pressurizing the mold and hardening. CONSTITUTION:Cement paste 4 is blended with foamed particles of synthetic resin and cast into a mold 2 having fine pores. Then the mold 2 is pressurized by a pressing machine 1, the foamed particles 5 of synthetic resin are deformed, filling ratio of the foamed particles is increased to the closet packing or more and excessive cement paste 6 is discharged through the fine pores 3 to the outside of the mold. After discharge of the excessive cement paste 6 is completed, a mixture having increased filling ratio of the foamed particles of synthetic resin is hardened to give a light-weight molded article having high degree of light weight and improved heat-insulating performance. The above-mentioned hydraulic cement, water and the foamed particles of synthetic resin can be mixed with an admixture comprising calcium chloride as a main component and at least one of an iron salt, an ammonium salt and a potassium salt as an auxiliary component and consequently, initial strength, strength and heat resistance of molding can be improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for producing a lightweight cement molded body containing foamed synthetic resin particles, and more specifically to a method for producing a lightweight cement molded body containing a high content of the foamed particles, which has excellent heat insulation properties. The present invention relates to a method for manufacturing a lightweight cement molded body.

[Conventional technology]

Conventionally, lightweight cement molded bodies have been manufactured by filling organic or inorganic lightweight aggregate or air during mixing or molding cement paste, and hardening it in a mold. Furthermore, foamed synthetic resin particles are widely used as lightweight aggregates because they are lightweight and have excellent heat insulating properties, moldability, and the like.

[Problem to be solved by the invention]

However, in the conventional method, the weight of the molded product obtained is almost determined when the cement paste and lightweight aggregate are injected into the mold, and the bulk density of the conventional product is 0.8 to 1.2 g/ad.
The weight reduction work ends there. That is, the amount of lightweight aggregate that can be filled is inevitably determined at the time of crosstalk. Further, even when considered theoretically, it is impossible to achieve the closest packing, and only a maximum filling rate of about 50% can be obtained. Therefore, in conventional methods, the degree of weight reduction of the molded body often depends on the cement that is the main component in the molded body, and there is a limit to the weight reduction.

In addition, in order to obtain a lightweight concrete molded body with a uniform distribution of foamed particles, the mold is first filled with synthetic resin foamed particles, and then compressed, so that the surface of each particle overlaps the surface of the adjacent particle. A method has been proposed in which a mixture of cement and water is forced into the surface of adjacent particles, but a gap is left between the surfaces of the adjacent particles, and the mixture is then hardened (Japanese Patent Application Laid-Open No. 151925-1983). However, although this method improves the uniformity of the distribution of foamed particles, it hinders uniform filling of the cement paste. Furthermore, when filling small-sized foam particles to reduce weight and increase the filling rate, uniform filling can hardly be expected; in such cases, the adhesion between the foam particles decreases. However, a practical molded body cannot be obtained.

Accordingly, one object of the present invention is to provide a method for manufacturing a lightweight cement molded body having a high content of foamed synthetic resin particles, that is, a high degree of weight reduction, and having excellent heat insulation properties.

[Means to solve the problem]

According to the present invention, in a method for manufacturing a lightweight cement molded body, in which a cement paste mainly composed of hydraulic cement and water and synthetic resin foam particles are injected into a mold and hardened,
A mold having fine holes is used as the mold, and after the cement paste and foam particles are injected into the mold, the excess cement paste is removed through the fine holes of the mold by pressurizing the inside of the mold. Provided is a method for producing a lightweight cement molded body, which comprises discharging the cement out of the system and then hardening it.

That is, in the manufacturing method of the present invention, first, cement paste and foamed synthetic resin particles are poured into a mold having many fine discharge holes, and then the foamed synthetic resin particles are deformed by pressurizing the inside of the mold. By increasing the filling rate of the foamed particles to close packing or higher, excess cement paste is discharged from the system, and then the mixture with the increased filling rate of the synthetic resin foam particles is cured.

With such a configuration, it is possible to easily obtain a lightweight cement molded body with a high content of foamed synthetic resin particles and improved heat insulation properties.

Next, the present invention will be explained with reference to the drawings. 1 and 2 are schematic cross-sectional views showing the state of the raw material mixture injected into the mold before and after pressurization, for explaining the present invention. Moreover, FIGS. 3 and 4 are partial plan views showing one example of micropores, respectively.

In FIGS. 1 to 4, 1 represents a press, 2 represents a mold having fine holes, and 3 represents fine holes.

First, foamed synthetic resin particles 5 are mixed with cement paste 4 and poured into mold 2 having fine holes. The state immediately after the injection is shown in FIG. Next, as shown in FIG. 2, by pressurizing the inside of the mold 2 with the press 1, the synthetic resin foam particles 5 are deformed, and the filling rate of the foam particles increases to close packing or higher. , the excess cement paste 6 is discharged to the outside of the formwork 2 through the fine holes 3. After the discharge of the excess cement paste 6 is completed, the mixture with increased filling rate of synthetic resin foam particles is hardened, and a lightweight cement molded body with a high degree of weight reduction and improved heat insulation performance is obtained.

The raw materials used in the present invention mainly include hydraulic cement, water, and foamed synthetic resin particles.

Examples of hydraulic cement include portland cement, silica cement, masonry cement, fly ash cement, lime mixed cement, high sulfate cement,
Examples include various conventionally known hydraulic cement materials for mortar cement and concrete, such as granulated blast furnace cement and alumina cement.

In addition, as the synthetic resin foam particles, any of thermoplastic resin foam particles such as polystyrene, polyolefin, and polyacrylic resin, and thermosetting resin foam particles such as polyurethane and phenol resin may be used. Thermoplastic resin foam particles are preferred from the viewpoint of flexibility when pressurized inside.

As thermoplastic resin foam particles, polystyrene, polyα
- Polystyrene foam particles based on methylstyrene, styrene/α-methylstyrene copolymer, etc., high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, Polyolefin foam particles based on propylene-ethylene random or block copolymers, propylene-butene-1 random or block copolymers, polyacrylamide, polyacrylonitrile, polyacrylic acid, polymethyl methacrylate, polyester, etc. Examples include polyacrylic foamed particles based on methyl acrylate or the like.

Note that the synthetic resin foam particles used in the present invention have a diameter of about 1-
It is preferable to have a bulk density of about 10+++m, and its bulk density is suitably about 0.01-0.2 g/a&. When foamed particles with a diameter of less than 1 mm+ are injected, the sum of the surface areas of all foamed particles increases and the amount of cement paste coating increases, making it difficult to reduce weight. On the other hand, if expanded particles having a diameter of more than 10 mm are injected, polka-dot-like irregularities will be formed on the surface, resulting in poor appearance. In addition, foamed particles having a bulk density of less than 0.01 g/cJ have a thin film thickness and a low material strength, so that when pressed, the bubbles burst, resulting in loss of heat insulation and sound absorption properties. On the other hand, if the bulk density is 0.2g
/ Even if foamed particles exceeding CD are used, no significant effect in weight reduction can be expected.

In the present invention, an admixture containing calcium chloride as a main component and at least one of iron salts, ammonium salts, and potassium salts as a subcomponent can be added to the hydraulic cement, water, and foamed synthetic resin particles. Adding the admixture at the time of mixing the hydraulic cement improves the adhesion between the cement and the foamed resin particles, leading to improvements in the initial strength, strength, and heat resistance of the molded product, which is preferable. In this case, iron salts include ferrous salts and ferric salts such as sulfates and chlorides, and anionic groups constituting ammonium salts and potassium salts include sulfate ions, carbonate ions, chlorine ions, etc. Examples include ions.

In addition, in the present invention, in addition to hydraulic cement, water, and foamed synthetic resin particles, asbestos, glass fiber,
Aggregates such as carbon fiber, vinylon fiber, polypropylene fiber, pulp fiber, aramid fiber, sand, gravel, pumice, volcanic lapilli, volcanic silica, and shirasu, polymers, and various additives can also be mixed.

In carrying out the present invention, the raw material composition as described above is mixed all at once using a batch-type or continuous-type mixer such as a gravity mixer or a continuous mixer, and then poured into a mold having fine holes. Various methods and formulations are adopted, such as a method in which foamed particles are not mixed all at once, but cement paste and foamed particles mixed with various additives are injected into the mold. after that,
By pressurizing the inside of the formwork with a press or the like in a pressure range of 0.01 to 150 kg/ad, preferably in a pressure range of 0.01 to 100 kg/cd, the pressure is increased while draining excess cement paste out of the system. After several hours, a lightweight cement molded body is obtained.

Note that the formwork with micropores used in the present invention is a formwork in which holes with a diameter of about 0.5 to 5 m are provided, but
It is also possible to use a formwork with a network of holes from 0 to 4 meshes. In addition, when injecting the cement paste and the foamed particles above it into the mold in this order, it is sufficient that only the upper mold has micropores. and/or used for the lower mold.

The lightweight cement molded product obtained by the present invention has a high proportion of foamed synthetic resin particles in the molded product and has excellent heat insulation performance, so it can be used for applications such as heat insulation, wall materials, ceiling materials, flooring materials, etc. It is expected to be useful in a wide range of architecture and civil engineering fields.

〔Effect of the invention〕

In the manufacturing method of the present invention, after the raw material mixture is injected into a mold having fine pores, by pressurizing the inside of the mold, excess cement paste is discharged out of the system through the fine pores of the mold. The filling rate of the foamed synthetic resin particles can be increased, and as a result, by the manufacturing method of the present invention, a lightweight cement molded body with a high degree of weight reduction and high heat insulation properties can be obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 to 6 and Comparative Example 1 600 g of white cement, 300 m12 of water, and cement mixture [Strong Leak Non; Eldant Chemical Industry ■
A cement paste obtained by kneading 50 g of the cement paste obtained by kneading 50 g of the foamed particles shown in Table 1 was mixed, and a molded body was obtained under the press hardening conditions shown in Table 2.

Comparative Example 2 The expanded particles shown in Table 1 were filled into a mold and then compressed leaving voids. After that, Examples 1-6 and Comparative Example 1
Cement paste obtained in the same manner as above was press-fitted to obtain a molded body under the curing conditions shown in Table 2.

Note) LDPE: High-pressure low-density polyethylene LLDP
E...Linear low density polyethylene PP...
Ethylene-propylene random coelectric composite mainly composed of polypropylene Table 2 Note) (2) Internal pressure of the two frames Next, regarding the above molded product, the density of the molded product, the appearance,
The homogeneity and bubble state of the cement were examined using the following evaluation criteria, and the results are shown in Table 3.

(Evaluation criteria) *1. Appearance (presence of polka dot pattern and cement peeling) *2゜ Uniformity of cement (cut the molded body and observe the cut surface) *3. Cellular state (measure the degree of cement impregnation into the foamed particles using the same method as *2) Table 3

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the state of the raw material mixture injected into the mold before being pressurized, and FIG. 2 is a schematic cross-sectional view showing the state of the same mixture when it is pressurized. Moreover, FIGS. 3 and 4 are partial plan views showing one example of micropores, respectively. 1...Press machine, 2...Formwork having micro holes, 3.
... Micropores, 4... Cement paste, 5... Synthetic resin foam particles, 6... Surplus cement paste.

Claims (2)

[Claims] (1) In a method for producing a lightweight cement molded body, in which a cement paste mainly composed of hydraulic cement and water and foamed synthetic resin particles are injected into a mold and hardened, the mold has micropores. Then, after injecting the cement paste and foam particles into the mold, pressurize the inside of the mold to discharge excess cement paste out of the system through the micropores of the mold, and then harden. A method for producing a lightweight cement molded body, characterized by: (2) The method for producing a lightweight cement molded body according to claim (1), wherein the cement paste contains an admixture containing calcium chloride as a main component and at least one of iron salt, ammonium salt, and potassium salt as a subcomponent. .