JPH0768737B2 - Manufacturing method of cylindrical block - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a tubular concrete block such as a box culvert.

<< Prior Art >> A mold for manufacturing a tubular block includes a box-shaped outer mold and a cylindrical middle mold mounted between the outer molds. In a formwork in which the middle mold is mounted horizontally, a space whose upper side is not opened is formed between the bottom face of the middle mold and the bottom face of the outer mold, and the concrete that flows into this space (in this specification, means mortar is included). When the air, excess water, cement paste, sand, etc. contained in
The discharge is blocked by the bottom surface of the middle mold, large bubbles and water bubbles are formed in the portion in contact with the bottom surface of the middle mold, and the slump value of the concrete in the portion increases. When the concrete is solidified in this state, a crater 10 as shown in FIG. 4 is formed on the inner surface of the molded tubular block, and the quality of the product is significantly deteriorated.

As one method for solving this problem, a mold having a structure in which the bottom surface of the middle mold is permeable has been proposed. FIG. 3 is a view showing an example of such a mold frame. An outer mold 3 provided with a side plate 1 and a end plate 2 which can be opened and closed, and a middle mold 5 which is inserted horizontally through a through hole 4 of the end plate 5 It has and. The middle die 5 is divided into a bottom frame 8 forming the bottom surface thereof and a gate frame 7 having an opening 6 for mounting the bottom frame. Tubular block 9
Is molded by pouring concrete into a horizontal hollow space formed when the outer mold and the middle mold are assembled. The middle mold 5 is removed from the molded block by removing the bottom frame 8 and squeezing the portal frame 7.

The molding surface of the bottom frame 8 is formed of punching metal 11 having a large number of ventilation holes, and the cloth 12 is attached to the outside of the punching metal during molding. The air bubbles and water bubbles generated on the bottom surface of the middle-sized mold 8 are the texture of the cloth 12 and the punching metal 11
The crater 10 shown in FIG. 4 is prevented from being generated because it is discharged through the through hole.

<< Problems to be Solved by the Invention >> The method of using a mold having a structure as shown in FIG. 3 is considered to be the best method for preventing the formation of craters on the inner surface of the cylindrical block. However, when molding is performed with the mold having the above structure, the moisture in the concrete in the portion in contact with the bottom frame 8 is excessively removed, so that a fragile layer having a coarse texture is formed in the portion, and the fragile layer portion flows. After the loss of the property, the water that rises from underneath the water stays in the lower part of the brittle layer and the concrete solidifies. As a result, the surface formed by the bottom frame 8 becomes a rough surface, the crater hidden under the roughened fragile layer reduces the strength of the block, and when an impact is applied, the fragile layer sinks and the crater collapses. There was a problem that was revealed.

The present invention aims to solve the above problems,
It is an object of the present invention to provide a method capable of preventing a crater or a fragile layer from being generated in a horizontally mounted middle-sized lower portion, and thus capable of manufacturing a tubular block having high strength and excellent surface properties. There is.

<< Means for Achieving the Object >> The method of the present invention is a mold including an outer mold 3 and a cylindrical middle mold 5 horizontally mounted on the outer mold, the middle mold 5 being on the bottom surface. This is carried out by using a form frame composed of a portal frame 7 having an opening 6 and a separable bottom frame 8 attached to this opening, and is adopted for forming a tubular block. According to the method of the present invention, an extra swelling portion of concrete is formed in a portion formed on the bottom surface of the middle mold 5 before the concrete is solidified.
By forming 19 and moving the bottom frame 8 (or the temporary bottom frame 23) of the middle mold 5 horizontally, the concrete in the raised portion 19 is removed to the outside of the mold 14.

As a method of forming the raised portion 19, the concrete 16 is poured into the formwork 14 and then left for a period of time during which bubbles and water bubbles rise, and then the bottom frame 8 is once removed and generated at the contact portion with the bottom frame 8. Air bubbles and water bubbles 17 on excess concrete
By filling 18 and filling, or by preparing a temporary bottom frame 23 in which a recess 22 having a depth of about 5 mm is formed on the molding surface, and by pouring concrete 16 into the formwork assembled using this bottom frame 23 A method of making the lower portion of the middle mold 5 thicker than the product thickness can be adopted.

Then, while the rising portion 19 is still soft, the temporary bottom frame 23 is pulled out in the horizontal direction and then the bottom frame 8 is attached, or the bottom frame 8 is moved in the horizontal direction and fitted into the middle die 5, Excess concrete in the raised portion 19 is scraped out of the mold 14 at the end of the bottom frame 8 or the end of the recess 22 of the temporary bottom frame 23.

<< Operation >> According to the above method, the air and excess water rising from the concrete that has flowed into the space between the bottom surface of the middle mold 5 and the bottom surface of the outer mold 3 are generated when the rising portion 19 is removed. It is excluded from the formwork together with the concrete of the part, and after these are removed, the surface of the block of the part is molded by the bottom frame 8 which is newly mounted, and the crater and the brittle layer do not occur, and the molding surface is good. become.

<< Embodiment >> FIG. 1 is a longitudinal sectional view showing the first embodiment of the present invention in the order of (a) to (f). First, a box-shaped outer die 3 in which a side plate 1 and a gable plate 2 are erected on a base 13 is assembled, and a through hole 4 of the gable plate 4 is assembled.
The portal frame 7 of the medium mold 5 is inserted into the above, the portal frame 7 is expanded, and the bottom frame 8 is fitted and fastened to the opening 6 to assemble the frame 14 (a). Next, a slump value of 6 to 10 is placed in the cylindrical space 15 of the formwork 14.
Pour the concrete 16 from while vibrating and compacting.
10 to 20 minutes after the pouring is completed, air, a part of water, cement and sand are gathered in the lower part of the medium-sized mold 5 to generate bubbles and water bubbles 17, and the concrete of about 3 to 5 mm from the contact surface with the bottom frame 8 is generated. The layer has a slump value of about 12 (b). Formwork 14 at this point
The bottom frame 8 is removed from (c), and the mortar 18 at the 12th position of the slump is poured into the exposed portion to fill bubbles and water bubbles to form a raised portion 19 (d). Next, the bottom frame 8 is pushed in horizontally from one end of the opening 6 of the gate frame 7 without entraining air (e). This creates extra bulge
19 is pushed out to the opposite side at the tip of the bottom frame 8 and discharged to the outside of the mold 14 (f). Finally, while holding the bottom frame 8 so that it does not rise, it is rubbed back and forth about 20 times to conform to the concrete surface and then fixed to the gate frame 7 and cured. When the curing is completed, the mold 14 is opened and the cylindrical block 9 is demolded.

FIG. 2 shows a second embodiment of the present invention, which is a method of using a temporary bottom frame 23. There is a recess on the molding surface of the temporary bottom frame 23.
22 is formed, and a formwork assembled by using the bottom frame 23.
The bottom of the void 15 formed in 14 is thicker by the depth of the recess 22 than the wall thickness of the block to be molded (a).
Then, concrete is poured into the void 15 while vibrating and compacting (b), and 10 to 20 minutes after the pouring is completed, the bottom frame 8
Remove (c). Raised part 19 molded in the recess 22
Bubbles and water bubbles 17 are generated on the surface, and the slump value is about 12 in the concrete layer 3 to 5 mm from the contact surface with the bottom frame 23. Therefore, a regular bottom frame 8 having no recess is horizontally inserted from one end of the opening 6 of the gate frame 7 in the same manner as in the first embodiment to scrape out the concrete of the raised portion 19 formed by the recess 22 (e ), The bottom frame 8 is reciprocally rubbed against the concrete surface to be fixed to the form frame, and cured to solidify the block.

<< Effect of the Invention >> As described above, according to the method of the present invention, air bubbles and water bubbles generated when pouring concrete into a mold can be reliably removed, so that the inner surface of the cylindrical block has craters that are rough or fragile. There is an effect that it is possible to manufacture a high-quality cylindrical block that is dense, has high strength, and has excellent surface properties without forming a layer.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of the present invention in the order of steps, FIG. 2 is a vertical sectional view showing a second embodiment of the present invention in the order of steps, and FIG. 3 is used in a conventional method. FIG. 4 is an exploded perspective view of the mold, and FIG. 4 is a perspective view showing the crater of the tubular block. In the figure, 3: Outer mold, 5: Middle mold, 6: Opening, 7: Gate frame, 8: Bottom frame, 15: Empty space, 16: Concrete, 19: Rise, 22: Recess, 23: Temporary bottom frame

Claims (2)

[Claims] 1. A mold (14) is assembled by horizontally mounting a cylindrical middle mold (5) having a separable bottom frame (8) on an outer mold (3), and the mold is emptied. The concrete (16) is poured into the place (15), the bottom frame (8) is once removed before the concrete is solidified, and extra concrete (18) is poured into the opening after the removal to raise the bulge (19). To form
Before the rising portion solidifies, the bottom frame (8) is horizontally inserted into the middle mold (5) to push the excess concrete of the rising portion (19) out of the form (14), and then the bottom frame (8). ) Is fixed to the middle mold (5) and the concrete in the mold (14) is solidified. 2. A temporary bottom frame (2) having a recess (22) on the molding surface.
3) is replaced with a regular bottom frame (8), and the tubular middle mold (5) is horizontally mounted on the outer mold (3) to assemble the mold (14), and the empty space of the mold. The concrete (16) is poured into the (15), and the temporary bottom frame (2
3) is removed and this temporary bottom frame is moved horizontally to remove it, or the bottom frame (8) is horizontally inserted into the middle mold (5) and the raised portion (19) is formed by the recess (22). A cylinder characterized by pushing out excess concrete from the outside of the formwork (14) and then fixing the regular bottom frame (8) to the middle formwork (5) to solidify the concrete in the formwork (14). Of manufacturing shaped blocks.