JPS6150918B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glazed cement pipe used as a pipe for construction and civil engineering.

Cement pipes can be made large in diameter and long, and have good dimensional accuracy, so
Widely used as construction and civil engineering pipes in place of traditional clay pipes. However, as is well known, cement pipes not only lack chemical resistance, but also allow water to penetrate into the pipe, resulting in corrosion of the inner surface of the pipe due to drainage of acidic liquid, etc., and damage when used as electrical cable pipes. There were inconveniences such as the risk of electrical leakage.

To solve this problem, it may be possible to glaze the inner surface of the cement pipe and fire it, but it is more difficult to uniformly heat and fire thick-walled pipes than thin-walled pipes. It was hot. In other words, when firing thin-walled tubes and thick-walled tubes in a furnace, the entire tube approaches the ambient temperature in a short period of time in response to changes in ambient temperature, but in the case of thick-walled tubes, the surface area changes However, the temperature inside the tube does not rise that much, so a relatively large temperature difference occurs between the surface and the inside of the thick-walled tube during firing. Further, the amount of expansion of the tube during hydration after firing becomes larger as the wall becomes thicker. As a result of these factors, thick-walled glazed cement pipes have the disadvantage that cracks tend to form on their inner and outer surfaces.

The present invention was made in view of the difficulty in firing cement pipes after glazing, as described above, and its purpose is to improve chemical resistance and attack by water, etc., without reducing strength. An object of the present invention is to provide a method for manufacturing a glazed cement pipe that can prevent see-through.

The gist of the present invention is to form a thin-walled tube from a kneaded mixture of cement, aggregate, water, etc. mixed in a desired ratio, apply an appropriate glaze to the inner peripheral surface of the thin-walled tube,
After firing the thin-walled tube at a desired temperature and time, the entire outer periphery of the fired thin-walled tube is coated with a cement mixture prepared at a desired ratio to form a thick-walled tube with a desired external shape.

The present invention will be described below based on drawings showing embodiments thereof.

For example, 100 parts by weight of cement, 200 parts by weight of silica,
A mixture of 45 parts by weight of water was kneaded for 5 minutes, and the resulting kneaded product was molded into a cylindrical mold with an inner diameter D of 500 mm, a length l of 2430 mm, and a thickness t, as shown in Figure 1.
Form it into a cylindrical shape with a thickness of 15 mm (if you want the final product, the glazed cement tube, to have a thickness of 42 mm). The thin-walled tube obtained in this way was heated to 50°C.
By steam curing at 95% relative humidity and curing for 15 hours, the thin-walled tube 1 is obtained. Next, the entire inner peripheral surface of the thin-walled tube 1 is coated with a glaze such as enamel glaze. The type of glaze is determined based on chemical resistance and crack resistance during firing, depending on the intended use of the product pipe.
It is desirable to select an appropriate one. After firing the glazed thin-walled tube in this way at a temperature of 850°C for 30 minutes, if the glazed thin-walled tube is cooled, as shown in FIG. is obtained. Next, each reinforcing bar (generally 2.4
As shown by the broken line in FIG. 4, the reinforcing bar cage 7 assembled in a cage shape is fitted onto the fired thin-walled tube 3 using ordinary iron wire (~6 mm diameter). This is placed in a steel mold frame 8, and the mold frame 8 is placed on the wheels 9 of a centrifuge, as shown in FIG. Furthermore, the mold frame 8 is slowly rotated while a cement mixture (so-called mortar) prepared in a desired ratio is introduced into the gap between the inner surface of the mold frame 8 and the outer peripheral surface of the fired thin-walled tube 3.
The cement used here may be Portland cement, alumina cement, or mixed cement. The cement kneaded material contains a dispersant,
An AE agent (air admixture agent), a binder, etc. may be added, and reinforcing materials such as glass fiber, steel fiber, and metal wire may also be added. After filling is completed, the rotation speed of mold frame 8 is gradually increased.
The charged kneaded material is pressed against the inner circumferential surface of the mold frame 8, and a thick-walled tube 10 is formed as shown in FIG. In order to accelerate the hardening of the kneaded product, the centrifugally formed kneaded product is stored in a steam curing chamber and heated by sending steam. Next, the temperature in the steam curing chamber is gradually lowered until there is no significant difference in temperature from the outside air, and then the tube is removed from the steam curing chamber and demolded. It is desirable that pipes be cured in a wet environment to maintain watertightness even after steam curing, and this is especially necessary for pressure pipes, so they are cured in water or by sprinkling water. in this way,
By steam-curing the pipe, a final glazed cement pipe 10 shown in FIG. 4 is obtained. No change was observed in the glazed surface 2 of the glazed cement pipe 10 even after being immersed in 10% hydrochloric acid (HCl) for 24 hours.

As detailed above, according to the present invention, once
After forming the thin-walled tube, the inner circumferential surface of the thin-walled tube is glazed and fired, so that cracks and the like do not occur on the glazed surface, and therefore there is no lack of chemical resistance. Furthermore, since a thick-walled pipe is formed based on a thin-walled pipe that has been glazed and fired, it is possible to provide a pipe for construction and civil engineering that has superior strength and chemical resistance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a thin-walled tube used in the present invention;
FIG. 2 is a perspective view showing a fired thin-walled tube, FIG. 3 is a side sectional view showing a molding die, and FIG. 4 is a side sectional view showing an embodiment of the present invention. 1... Thin-walled pipe, 2... Glazed surface, 3... Fired thin-walled pipe, 10... Glazed cement pipe.

Claims (1)

[Claims] 1 Form a thin-walled tube using a kneaded mixture of cement, aggregate, water, etc. mixed in a desired ratio, apply an appropriate glaze to the inner peripheral surface of the thin-walled tube, and fire the thin-walled tube at a desired temperature and time. After that, the entire outer periphery of the fired thin-walled tube is coated with a kneaded mixture of cement, aggregate, water, etc. mixed in a desired ratio and formed into a thick-walled tube with a desired external shape. Method of manufacturing tubes.