JPH03151442A - Centrifugal reinforced concrete cylindrical body and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a concrete cylindrical body in high quality and low cost by burying reinforcement arranged in crossing direction against the axial direction in the thickness of the concrete cylindrical body, and forming an opening part through which reinforcement is partially exposed. CONSTITUTION:Reinforcement 1 is arranged inside a formwork 5 of square cylinder having a square section defining the external form of a concrete cylindrical body 10, triangular corner formworks 6 are provided inside the four corners of the reinforcement 1, and space between the corner formworks 5 is held at a decided value. Nextly, a slender air bag 7 is set inside the center of a decided plane of the formwork 5, and inflated. Nextly, air bags 8a, 9b, 9a, 9b are respectively set between the formwork 5 and the reinforcement 1, and between the reinforcement 1 and the corner formworks 6, and inflated. After hardening of concrete placed in the formwork 5, air is drawn out from the air bags 7, 8a, 8b, 9a, 9b and the air bags are removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a centrifugally formed concrete cylinder suitable for use as an outer shell when constructing a reinforced concrete column, and a method for manufacturing the same.

(Prior art) Japanese Patent Publication No. 61-31261 and Japanese Patent Publication No. 1-30988
As disclosed in the above publication, there is a construction method in which a precast concrete cylinder is used as the outer shell of the column when a reinforced concrete column is cast in place. In this case, reinforcing bars are arranged within the wall thickness of the precast concrete cylinder in a direction intersecting the axial direction. At the concrete column construction site, reinforcing bars are placed along the length of the column.
The reinforcing bars are arranged to pass through the hollow part of the precast concrete cylinder, and concrete is poured into the hollow part.

The above-mentioned patent publication also discloses a precast concrete cylindrical body that becomes the outer shell of a beam that is connected to a column to be constructed as described above. The cylinder is a square cylinder with square hoop reinforcing bars arranged, but one of the four sides has no concrete (the concrete is in the shape of a U-shaped groove).
The hoop rebar is exposed on that side.

(Problem to be Solved by the Invention) The above-mentioned precast concrete cylinder is produced by stacking an outer formwork and an inner formwork with a predetermined space in between, pouring ready-mixed concrete between them, and using a vibrator. It was then compacted. When the concrete cylinder is manufactured by vibratory compaction, it is difficult to reduce manufacturing costs, and there are problems in that the quality of the concrete is inferior compared to centrifugal force forming, and it is also difficult to form openings that expose reinforcing bars in arbitrary positions. There was a problem in that the degree of freedom regarding the position, size, and shape of the opening was low.

This invention was made in view of the above-mentioned conventional problems.The purpose of this invention is to manufacture a concrete cylinder having an opening in which reinforcing bars are partially exposed at a high quality and at a low cost, and to position the opening. , size, and shape can be easily and freely selected.

(Means for Solving the Problems) Accordingly, the present invention provides a concrete cylinder in which reinforcing bars arranged in a direction intersecting the axial direction are embedded in the wall thickness, the concrete having an opening where the reinforcing bars are partially exposed. The cylindrical body is manufactured by centrifugal force forming. At that time, the embedded formwork for the opening is placed at a predetermined position on the inner surface of the formwork that defines the outer shape of the cylinder, and after the concrete hardens, the embedded formwork for the opening is removed from the mold and the embedded formwork for the opening is placed. An opening was formed in the exposed part. Preferably, an air bag inflated with pressurized air is placed at a predetermined position on the inner surface of a formwork that defines the outer shape of the cylinder as an embedded formwork for opening, and after the concrete hardens, the air bag is deflated and removed from the mold. An opening is formed in the area where the air bladder was placed.

(Function) The poured concrete is removed by the embedded formwork for openings, such as the air bag mentioned above, so when the embedded formwork for openings is removed, an opening with exposed reinforcing bars is formed there.

(Embodiment) FIG. 1 shows a centrifugally formed concrete cylinder 10 according to an embodiment of the present invention. The concrete cylindrical body 10 as a whole is formed into a rectangular cylindrical shape with a square cross section, and reinforcing bars 1 made of spiral hoop material bent into a rectangular frame shape are provided within the thickness of the concrete.

The concrete 11 body 10 is composed of four surfaces, and an opening 2 that is continuous in the longitudinal direction from the upper end to the lower end is formed in the center of one of the surfaces, and the reinforcing bars 1 are exposed in this opening 2. are doing. Further, a rectangular window-shaped opening 3 is formed on the other side, and the reinforcing steel 1 is also exposed in this opening 3. A small opening 4 cut downward from the upper end of the cylindrical body 10 is formed on the other surface, and the reinforcing bar 1 is also exposed in this opening 4.

The concrete cylindrical body 10 shown in FIG. 1 is manufactured by the centrifugal force forming method as follows, and is used as the outer shell of a reinforced concrete column when constructing it. In other words, this concrete cylindrical body 10 is erected at the site, and the main reinforcing bars of the columns are arranged in the hollow part, and the reinforcing bars of walls, beams, etc. to be constructed connected to this column are installed in the openings 2.3.4. It passes through the main concrete cylinder 10, and inside the main cylinder 10, columns, walls,
Connect each reinforcing bar such as a beam. Then, formwork for walls and beams is installed, and concrete is placed inside these formworks and within the concrete cylinder 10 to integrally construct columns, walls, beams, etc. As is clear from this description, the position, size, and shape of the opening in the concrete cylinder 10 used for the above purpose are determined depending on the design of the concrete structure to which it is applied.

The centrifugal force forming method for the concrete cylinder 10 described above will be explained using FIGS. 2 and 3.

FIG. 2 shows a set state of a formwork device for centrifugally forming the concrete cylinder 10 of FIG. 1. Reference numeral 5 denotes a formwork made of a rectangular cylinder with a square cross section that defines the outer shape of the concrete cylinder 10, and reinforcing bars 1 made of spiral hoop material are arranged on the inner side of the formwork so as to maintain a predetermined interval.
Furthermore, a triangular corner formwork 6 is placed inside the four corners of the reinforcing bar 1.
The distance between the corner formwork 6 and the formwork 5 is maintained at a predetermined value. The corner formwork 6 is provided to prevent concrete from being biased to the four corners of the formwork 5 during centrifugal molding, and to regulate the thickness of concrete at a portion of the corner.

A long opening 2 spanning the entire length of the concrete cylinder 10
In order to form a steel U
Inflate between J1 and J1.

Further, in order to form the opening 3, an air bag 8a of a predetermined size is set at a predetermined position between the mold crusher 5 and the reinforcing bar 1, and an air bag 8a is placed so that the reinforcing bar 1 is sandwiched between the air bag 8a and the air bag 8a. Set the bag 8b between the reinforcing bar 1 and the corner formwork 6,
Supply pressurized air to inflate it as shown in Figure 2.

In exactly the same way, an air bag 9a of a predetermined size and shape is set between the formwork 5 and the reinforcing bar 1 at a position corresponding to the opening 4, and the reinforcing bar 1 is sandwiched between this air bag 9a. The air bag 9b is set between the reinforcing bar 1 and the corner formwork 6 so that the air bag 9b is inflated as shown in FIG.

After inflating each air bag as described above, this formwork 5
A predetermined amount of concrete is poured into the container and compacted using the well-known centrifugal force forming method. Here, of course, the air bag 8a
, 8b are set, no concrete is filled. In particular, the reinforcing bar 1 is placed between the air bags 8a and 8b, but the inflated air bladders 8a and 8b surround the reinforcing bar 1, and the air bags 8a and 8b are in close contact with each other in the area where the reinforcing bar 1 is not present. There is. Therefore, concrete is not filled between the air bags 8a and 8b. The portion where the air bags 9a and 9b are provided is also the same as above.

The air bag 7 is located between the two corner formworks 6 and 6, and is set between the formwork 5 and the reinforcing bar 1, and no air bag is disposed inside it.

In the central part of this one surface, the thickness of the concrete becomes thinner due to the action of centrifugal force, and the amount of concrete poured is adjusted so that the thickness becomes such that the inner surface of the reinforcing bar 1 is exposed.

Once the concrete has hardened through centrifugal compaction,
Each air bag 7.8a, sb during demolding.

Remove the air from 9a and 9b. Then the third
As shown in the figure, an opening 2.3.4 is formed in the area where each air bladder was placed.

Further, FIGS. 4 and 5 show a modified example of the embedded formwork for the opening. The one shown in Fig. 4 is formed by making holes 11a for reinforcing reinforcing bars and notches 11b for fitting reinforcing bars into the holes 14a in a formwork 11 made of a rubber-based material such as urethane rubber. be. In addition, in the case shown in FIG. 5, a notch 12b is formed in a formwork 12 made of a material such as polystyrene foam to divide the formwork 12 into two in correspondence with the placement position of reinforcing bars, and at the position of the notch 12b. Holes 12a for reinforcing bars are formed along the sides. In the case shown in FIG. 4, the formwork 11 is placed in a predetermined position so that the reinforcing bars are inserted into the holes 11a, and the fifth
In the figure, the formwork 12 is assembled and arranged so as to sandwich the reinforcing bars from both sides.

Of course, even in these modified examples, effects similar to those described above can be achieved.

(Effects of the Invention) As described above in detail, according to the present invention, a concrete cylinder having an opening where reinforcing bars are exposed at any part can be produced with high quality and at a low cost by centrifugal force forming. can. In particular, in the case of a concrete cylinder used as an outer shell when constructing a reinforced concrete column, the position, size, shape, etc. of the opening need to be selected in various ways. According to the present invention, which uses an embedded mold, especially an air bag as the mold, various demands can be easily met.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a centrifugally formed concrete cylinder according to an embodiment of the present invention, Fig. 2 is a sectional view of a formwork device for centrifugally forming the above concrete cylinder, and Fig. 3 is the above formwork. A sectional view of the concrete cylinder removed from the apparatus, and FIGS. 4 and 5 are perspective views showing a modification of the embedded formwork for opening. 1...Reinforcement bar 2.3.4...Opening 5...Formwork 6...Corner formwork 7.8a, 8b, 9a , 9 b・
−・−Air bag 10・・・・Concrete cylindrical body

Claims (3)

[Claims] (1) A centrifugally formed concrete cylindrical body in which reinforcing bars arranged in a direction intersecting the axial direction are embedded within the wall thickness, the centrifugally forming concrete cylinder having an opening through which the reinforcing bars are partially exposed. Concrete cylinder. (2) When manufacturing the centrifugally formed concrete cylindrical body according to claim 1, an embedded formwork for opening is arranged at a predetermined position on the inner surface of the formwork that defines the external shape of the cylindrical body, and after the concrete hardens, the opening A method for producing a centrifugally formed concrete cylinder, the method comprising: removing the embedded formwork for opening, and forming the opening in a portion where the embedded formwork for opening was placed. (3) When manufacturing the centrifugally formed concrete cylindrical body according to claim 1, an air bag inflated with pressurized air is placed in a predetermined position on the inner surface of the formwork that defines the external shape of the cylindrical body in an embedding formwork for opening. A method for manufacturing a centrifugally formed concrete cylindrical body, in which the air bag is disposed as a cylinder, and after the concrete hardens, the air bag is removed from the mold, and the opening is formed in the part where the air bag was placed.