JPH0734787A - Manufacture of rc segment - Google Patents

Abstract

PURPOSE:To obtain a product having fine surface by a method wherein an air suction port is provided on the upper part of a tightly closed form to generate negative pressure in the interior thereof and highly flowable concrete is forced and loaded from below into the form and concrete pressure therein is maintained for a certain period. CONSTITUTION:An air suction port 18 is mounted to the upper part of a tightly closed segment form A through a valve B, and a concrete casting port 17 is provided at the lower part thereof. Next the air in the form A is drawn by means of a vacuum pump G to generate negative pressure and highly flowable concrete, which does not need to be compacted, is forced and loaded into the form by means of a concrete pump E. Thereafter conctrete pressure in the form A is maintained for a certain period of time to eliminate occurrences of air pits of small diameter or water pits due to bleeding water. By this method, a fine concrete product which eliminate the need for surface finishing can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an RC segment using superplasticized concrete that does not require compaction.

[0002]

2. Description of the Related Art Conventionally, when manufacturing an RC segment, a rebar cage b is set in a segment manufacturing form a as shown in FIG. 11, and concrete is poured from the top while applying vibration by a vibrator or the like. After placing a certain amount of concrete, attach a lid form c with an opening as shown in FIG. 12, place the concrete to the final placement level, and then remove the lid form c to finish. After a suitable curing time had passed, the top surface finishing work was carried out. In the figure, d is an injection pipe, and e is a joint metal fitting.

[0003]

According to the above-mentioned conventional method, concrete having a low water-cement ratio W / C and a small slump value is struck by using a strong vibrator in order to quickly finish the upper surface. It is necessary to set up. Therefore, a strong vibrator and a mold with high strength and rigidity to withstand the vibration are required, which increases the manufacturing cost. Further, the vibration and noise of the vibrator were large, and the effects on the surrounding environment were not negligible. on the other hand,
Since the top surface finishing work is done manually, it has a considerable effect on the quality of the product surface and the dimensional accuracy of the product.

As a solution to these problems, a method of placing concrete using a closed mold is conceivable. In this case, if the concrete is simply pressed into the mold, the entraps taken into the concrete are entrapped. As a result of experiments, it was found that the air gathered gradually on the lower surface of the upper mold even after casting, and remained as air pock after the concrete was cured, which is an important issue from the appearance and quality of the product. found.

The present invention has been proposed in view of the above-mentioned problems of the prior art, and its object is to remove air patters and surfaces generated on the concrete surface by the air caught in the concrete during casting. Another object of the present invention is to provide a method for producing an RC segment that has no water patter due to the generated breathing water.

[0006]

In order to achieve the above object, according to the method of manufacturing an RC segment of the present invention,
After the high-fluidity concrete that does not need to be compacted is press-fitted and filled in the closed segment formwork, the concrete pressure in the formwork is maintained for a certain period of time. According to a second aspect of the present invention, a negative pressure is applied to the inside of the mold to suck air from the upper part of the mold, and concrete is press-fitted and filled in the mold.

[0007]

According to the present invention, as described above, the conventional method of placing concrete by pouring from the upper part of the mold by press-fitting and filling the compacted high-fluidity concrete into the closed segment mold. As in, the air entrained when the concrete falls and flows in the form is reduced. Further, by maintaining the concrete pressure for a certain period of time, it is possible to suppress the generation of air patters having a minute diameter which occur in the concrete in the formwork, and improve the compressive strength of the concrete.

According to the second aspect of the present invention, a negative pressure is applied to the inside of the form, and the concrete is press-fitted into the form while suctioning air from the upper part of the form. The generation of innumerable minute air flutter generated in concrete is reduced, and breathing does not occur.

[0009]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an outline of the implementation status of the method of the present invention, A is an RC segment formwork, a concrete pouring port is provided in the lower part, and an air suction port for lowering the internal air pressure is provided in the upper part, A forked valve B, which will be described later, is connected to each of the setting port and the suction port.

As the lower valve B reaches the base end side,
Concrete pumping pipe D through connecting pipe C whose diameter is gradually reduced
Is connected, and the same pressure feed pipe D is connected to a squeeze type concrete pressure feed pump E, and is configured so that the amount of concrete press fit can be adjusted by inverter control. F in the figure
Is a concrete mixer for supplying concrete to the pump E.

On the other hand, the valve B on the upper part of the mold A is connected to the vacuum pump G. 2 and 3 show an embodiment of the form A, in which the front, rear, left, right, and upper and lower 6 surfaces are made of steel plate 1, and the form is set on the outer peripheral surface in various directions so that the mold falls. A support 2 for preventing deformation is provided so as to project. In the figure, 3 is a joining flange. At the end of the form A, as shown in FIG. 4, the rubber packing 5 is interposed at the end joining portion of the steel plate 1 by the bolt 4 to keep the form waterproof.

FIG. 5 shows the details of the valve B, in which the airtightness of a known valve manufactured by Saga Industry Co., Ltd. is further increased. In the figure, 11 is a fluororesin plate thrust ring, 11a is a thrust retainer, and 13 is a grease nipple. Next, a method of manufacturing the RC segment in a state where the form A is placed horizontally as shown in FIG. 6 will be described.

The form A has a concrete pouring port 17 connected to a concrete pump and an air suction port 18 connected to a vacuum pump, and a rebar cage 19 is inserted as shown in FIGS. 7 and 8. In the figure, 20 is a joint metal fitting. After cleaning the form A, the following high-fluidity concrete is poured and filled. The mix of concrete used is as follows.

[0014]

[Table 1]

[0015]

[Table 2]

The properties of the fresh concrete with the above composition are as follows. Slump flow: 60 to 70 cm V funnel flow time: 10 seconds or less In Table 2, Ad. 1 is a high performance AE water reducing agent. After the concrete of the above mixture mixed by the concrete mixer F is press-fitted from the concrete pouring port 17 and it is confirmed that the concrete has entered the mold A, the vacuum pump G is used to blow the air in the mold from the air suction port. While suctioning the concrete, the concrete is pressed into the form A through the pouring port 17 and filled, and after confirming that the concrete has reached the air suction port 18, the vacuum pump G is stopped and the air suction port 18 is closed. . After that, the concrete pressure in the form A is maintained for a certain time by the concrete pressure pump E, and then the concrete pouring port 17 is closed to finish the concrete pouring.

When the concrete pouring port 17 is closed, it is closed by the valve B, so that after pouring the concrete, there is no step between the pouring port 17 and the concrete pouring surface around the pouring port, and it is smooth. A concrete surface is formed. In this case, since the state of press-fitting concrete into the form A is maintained for a certain period of time, air puddle and water puddle are hardly generated, and those holding the concrete pressure for a certain period of time are more compressed than others. Strength increased.

Regarding the mixing of concrete, when the admixtures such as fly ash and blast furnace slag are mixed and the properties of the fresh concrete are the same, the RC segment can be manufactured by the same method as described above. Moreover, even if the form A is arranged in a mountain shape as shown in FIG.
It was confirmed that even with the inverted mountain shape as shown in 0, the concrete can be press-fitted and there is no problem in the quality of the concrete. In each drawing, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals.

It should be noted that the present invention is not limited to the production of RC segments, but can be applied to the production of any concrete secondary product. Furthermore, concrete is poured into a closed steel shell such as a steel-concrete composite segment. It is also applied in the case of doing.

[0020]

According to the method of the present invention, as described above,
After press-fitting and filling high-consolidation concrete that does not need to be compacted into the closed segment formwork, the concrete pressure in the formwork is maintained for a certain period of time, so that the concrete is mixed during kneading of the concrete and during press-fitting into the formwork. The generation of air trapped inside can be suppressed, and the amount of entrapped air in the concrete that collects at the top of the form can be reduced. For this reason, it is not necessary to finish the upper surface as in the conventional case, so that the labor can be saved, and the quality of the product surface and the dimensional accuracy of the product are improved.

Further, there is no vibration or noise of the vibrator, the adverse effect on the surrounding environment is prevented, and the compressive strength of concrete is further increased. According to the invention of claim 2, as described above, a negative pressure is applied to the closed mold, and the air is sucked from the upper part of the mold to press-fit the concrete into the mold, thereby entrapping the concrete being press-fitted. Since the dry air can be removed, the air patter generated on the concrete surface can be removed more reliably, and the quality of the product can be further improved.

[Brief description of drawings]

FIG. 1 is a front view showing an implementation state of an RC segment manufacturing method according to the present invention.

FIG. 2 is a plan view of a mold for manufacturing an RC segment.

FIG. 3 is an arrow view diagram of FIG.

FIG. 4 is a partial vertical sectional view showing a joint portion of a mold.

FIG. 5 is a sectional view of a driving port valve.

FIG. 6 is a perspective view in which a part of an embodiment of an RC segment manufacturing form is cut away. However, the valves are omitted.

FIG. 7 is a cross-sectional plan view showing a state where a rebar cage is inserted in the mold.

8 is a vertical side view of FIG.

FIG. 9 is a perspective view showing an example showing a concrete pouring situation on an RC manufacturing form.

FIG. 10 is a perspective view showing another embodiment showing the situation of placing concrete on the RC manufacturing form.

FIG. 11 is a perspective view showing a concrete pouring state on a formwork in a conventional method.

FIG. 12 is a perspective view showing a lid frame mounted state in a conventional method.

[Explanation of symbols]

 A RC segment formwork B valve C connection pipe D concrete pressure feed pipe E concrete pressure feed pump F concrete mixer G vacuum pump 1 steel plate 2 support 3 joint flange 4 bolt 5 rubber packing 11 thrust ring 11a thrust presser 13 grease nipple 17 concrete pouring port 18 Air suction port 19 Reinforcing bar cage 20 Joint hardware 21 Injection pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichiro Ito 47-3 Mita, Atsugi, Kanagawa Sato Kogyo Co., Ltd. Central Technology Research Institute (72) Inventor Hiroshi Uno 47-3 Mita, Atsugi, Kanagawa Sato Kogyo Co., Ltd. Central Research Institute (72) Inventor Naoshi Okamura 4-12-20 Nihonbashihonmachi, Chuo-ku, Tokyo Sato Industry Co., Ltd. (72) Inventor Jun Sasaki 4-12-20 Nihonbashihonmachi, Chuo-ku, Tokyo Sato Industry Co., Ltd. (72) Inventor Norio Nishimoto 4-12-20 Nihonbashimotocho, Chuo-ku, Tokyo Sato Industry Co., Ltd. (72) Minoh Sugimoto Inakura-cho, Itakura-cho, Gunra Prefecture Gunma Prefecture, Saei Kenko Co., Ltd.

Claims (2)

[Claims] 1. A method for producing an RC segment, which comprises press-fitting and filling a compaction-free high-fluidity concrete into a closed segment formwork, and then maintaining the concrete pressure in the formwork for a certain period of time. 2. The method of manufacturing an RC segment according to claim 1, wherein negative pressure is applied to the inside of the mold to suck air from the upper part of the mold and concrete is press-fitted and filled into the mold.