JPS5857285B2 - Manufacturing method of concrete composite pipe with built-in steel pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manufacturing method for forming a concrete composite pipe containing a steel pipe using centrifugal force.

Traditionally, methods have been used to form a mortar or concrete layer on the outside of steel pipes for purposes such as rust prevention, reinforcement, or adding weight, but these are done by means such as spraying or hand painting. was.

In the case of these construction methods, the strength of the outer layer is affected by the construction conditions and the quality varies widely, and the work requires a relatively large amount of labor and time.

The present invention makes it possible to form concrete composite pipes with built-in steel pipes using a factory-controlled centrifugal force manufacturing method, thereby compensating for the shortcomings of conventional products and making it possible to manufacture high-strength, high-quality, and economical concrete composite pipes. It is.

An embodiment of the manufacturing method of the present invention will be explained with reference to the attached drawings. First, mortar or concrete to be the outer layer 2 is poured into the inner surface of a normal formwork 1, such as the one used for manufacturing centrifugal concrete products, using a conventional method. After forming the outer layer, the steel pipe 3 coated with adhesive on the outer periphery is moved from one side of the form 1 without removing the form 1 while the mortar or concrete is hardened or uncured. It is press-fitted inside the outer layer 2 as shown by the arrow P using a hydraulic device or the like.

After press-fitting the steel pipe, the formwork is placed on the centrifuge again and mortar or concrete is poured in to form the inner layer 4.
After forming, it is demolded and cured using a normal curing method to obtain a concrete composite pipe with a built-in steel pipe.

In the present invention, an adhesive (for example, an epoxy resin type adhesive) is applied to the entire outer periphery of the steel pipe to be inserted, so that the adhesive is well bonded to the outer layer of concrete and does not easily peel off.

It is preferable to avoid mixing aggregate with large particle size in the concrete mix that will become the outer layer during molding because of the possibility of peeling of the inner concrete part when press-fitting the steel pipe.

The finishing aspect of the product obtained by the present invention is such that the thickness of the inner layer mortar or concrete 4 is slightly thicker than that of the outer layer mortar or concrete 2, and the tip portion 6 is further formed on the end of the steel pipe on the ball-in side. When inserting into the inner surface of the outer layer 2, the weak strength portion 5 due to surplus water on the inner surface of the formed outer layer 2 is scraped off to improve the adhesion between the outer concrete layer 2 and the steel pipe 3. Also, the outer concrete layer 2 is formed. The degree of compaction during compaction is to prevent as much as possible the floating of excess water from the outer layer 2 during compaction of the inner concrete layer 4, and to prevent the floating of excess water from the outer layer 2 and the steel pipe 3.
In order to improve the adhesion with the inner layer 4, it is preferable to increase the compaction level by about 10%, and in some cases, it is preferable to mix an appropriate amount of expandable cement into the inner layer concrete to reduce chemical prestress. A high strength product is obtained at the point of application.

Of course, arranging reinforcing bars in the outer layer 2 and the inner layer 4 also brings about good results in terms of further increasing the strength.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of the inside of a mold during centrifugal molding according to the present invention, and FIG. 2 shows a part of a vertical sectional view during manufacturing. 1...Formwork, 2...Outer layer or concrete layer, 3...Built-in steel pipe, 4.
...Inner layer mortar or concrete layer, 5...
...The scraped outer layer of mortar or conc IJ-)
, 6...The tip of the steel pipe.

Claims (1)

[Claims] 1. When manufacturing a concrete composite pipe with a built-in steel pipe,
The outer layer of mortar or concrete is produced by normal centrifugal molding, then a steel pipe with adhesive applied to the outer periphery is inserted into the inner surface of the outer layer of concrete, and then the inner layer of mortar or concrete is placed inside the steel pipe and centrifugal force is applied. A method for manufacturing a concrete composite pipe that incorporates a steel pipe between the upper and lower layers formed as follows. 2. The method according to claim 1, wherein the tip of the steel pipe to be inserted is formed into a sword-point shape. 3. The method according to claim 1, wherein the degree of compaction during molding of the mortar or concrete serving as the outer layer is increased by the degree of compaction of the inner layer. 4. The method according to claim 1, wherein expandable cement is mixed into the inner layer mortar or concrete. 5. The method according to claim 1, wherein reinforcing bars are arranged in the inner layer and the outer layer.