JPH04255302A - Deaerating method of concrete member - Google Patents

Abstract

PURPOSE:To remove the bubbles on the front side of the concrete placed in a form without the occurrence of material-separation. CONSTITUTION:A rotatable rod 1 which has the length corresponding to the depth of a concrete member is put on the interface between the form F of the front side of the concrete C and the concrete C, and then said rod is moved along the surface of the form F, while it is rotated, whereby the whole concrete C is not vibrated, and then the bubbles on its front side are partially raised and is effectively removed without the occurrence of material-separation.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is a method for removing air bubbles from concrete members, which prevents the formation of cavities due to air bubbles existing on the surface of concrete members manufactured by pouring concrete into formwork before the concrete hardens. It is about the method.

0002

[Problem to be solved by the invention] Currently, the production of concrete parts by pouring into forms is based on a preset planned mixture made of raw materials specified by JIS, depending on the condition of the materials on site and the method of measurement. The slump value was adjusted to about 6±2cm to 8±2cm, and the air volume was adjusted to 5±1cm.
%, and the 28-day compressive strength is 300 kgf/cm2
After pouring the ready-mixed concrete into the formwork, which has been inspected and controlled to ensure the same level of consistency, it is compacted by external or internal vibration, resulting in uniform concrete that conforms to the shape, dimensions, appearance, bar arrangement, and strength test. The method used is to produce concrete products in factories.

However, in recent years, as the scope of application of concrete members has expanded, the products have tended to become larger, and the amplitude and vibration noise during vibration compaction have also increased accordingly.
The increasing size of concrete components is creating new problems such as the deterioration of the working environment in factories due to this noise and the impact on nearby areas, and countermeasures against this noise are essential for factory production.

[0004] To solve this problem, for example, by mixing admixtures such as fly ash with concrete to increase the fluidity of the concrete, concrete can be compacted as it is poured without applying vibrations, and the concrete can be compacted while being poured. This can be solved by eliminating the need for compaction, but this non-compaction concrete has a flow value of about 60 cm, is extremely fluid, and has the property of easily causing separation of aggregate and paste. When removing air bubbles that form on the surface after pouring, extreme care must be taken to prevent this separation from occurring.

[0005] Particularly, conventionally, air bubbles on the concrete surface side after pouring have been removed by inserting a plate-shaped part between the concrete surface and the formwork surface, and moving it up and down to destroy the air bubbles. , in the case of highly fluid concrete, there is a high possibility of material separation, and it is also not efficient.

[0006] This invention was made based on this background, and attempts to propose a new method for effectively removing air bubbles without causing material separation, especially when using concrete with high fluidity. It is something to do.

[0007]

[Means for Solving the Problems] In the present invention, a rotating rod having a length corresponding to the depth of the concrete member is inserted into the interface between the surface side of the concrete placed in the formwork and the formwork. By rotating this and moving it along the formwork surface, the air bubbles existing on the surface side of the concrete are partially raised without imparting vibration to the entire concrete.
This is effectively removed without causing material separation.

[0008] For the concrete, in addition to non-compacting concrete that does not require compaction by vibration, ordinary concrete is used, and spiral grooves are formed on the circumferential surface of the rotating rod to promote the rise of air bubbles. Make removal more efficient.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on drawings showing one embodiment.

The present invention provides a method for manufacturing a concrete member by pouring concrete C into a formwork F, as shown in FIG.
As shown in the figure, a rotating rod 1 having a length corresponding to the depth of the concrete member is inserted into the concrete C on the surface side that makes up the appearance of the concrete member before it hardens, and while rotating it, the formwork F is inserted. This is a method of removing air bubbles generated on the surface side of concrete C by moving them along the surface and raising them. Concrete C includes, for example, concrete used as underwater concrete that has a large slump and a flow value of about 40 to 60 cm and does not require compaction, as well as ordinary concrete that requires vibration compaction.

[0011] The work procedure will be explained.

[0012] First, the concrete C poured into the formwork F is given a preparatory time of about 0 to 60 minutes, and then the rotary rod 1 is inserted before the concrete C hardens. Rotating rod 1
As shown in the figure, formwork F on the surface side of the concrete member
The concrete C is inserted at one end in the moving direction up to the lower end position at the interface with the concrete C.

[0013] The rotating rod 1 has an outer diameter φ of about 5 to 50 mm and is connected to an electric motor 2 having a rotational capacity of about 10 to 1500 rpm.
It can be moved at low speed while maintaining a constant depth and angular velocity. The outer diameter φ of the rotary rod 1 and the rotation speed of the drive shaft of the electric motor 2 are adjusted according to the properties of the concrete C and the scale of the concrete member. For example, if the concrete C is soft, the outer diameter φ is thin, and if the concrete C is hard, the outer diameter φ is thick. A rotary rod 1 is used. Also, the length of the rotary rod 1 can be varied according to the depth of the concrete member.

[0014] The movement of the rotating rod 1 is 1/60 to 1/30 m.
This is done at a relatively slow speed of about 1/s.

The rotating rod 1 may be, for example, a rod having a uniform cross-section without irregularities over its entire length, but as shown in FIG.
By forming a spiral groove 1a continuously from the lower end on the circumferential surface of the tube, the effect of removing air bubbles can be enhanced. Air bubbles are taken into the continuous groove 1a, continue along the groove 1a, are guided by the air bubbles, are forcibly raised as the rotary rod 1 rotates, and are discharged into the outside air. In this case, the depth d of the groove 1a shown in FIG. 3, which is a partially enlarged view of FIG.
A depth d of m is given.

When the rotating rod 1 has a uniform cross-section, air bubbles are discharged from a gap temporarily created in the height direction between the circumferential surface of the rotating rod 1 and the concrete C at the same time as the rotating rod 1 moves. That will happen.

After the rotary rod 1 is moved to the other end and all air bubbles have been removed, the surface of the concrete C to be cast is leveled with a finishing trowel, the top end is finished smooth, and the air bubble removal work is completed. do.

[0018]

[Effects of the Invention] This invention is as described above, and since a rotating rod is inserted into the surface of concrete and its rotation is used to remove air bubbles without moving it up and down, air bubbles can be removed before hardening. Air bubbles can be effectively removed without causing material separation in the concrete.

[0019] In particular, by forming a spiral groove on the rotary rod, the air bubbles rise along the grooves, so that the evacuation effect is further enhanced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the working procedure of the present invention.

FIG. 2 is an elevational view showing a rotating rod with grooves formed on its circumferential surface.

FIG. 3 is a partially enlarged view of FIG. 2;

[Explanation of symbols]

C...Concrete, F...Formwork, 1...Rotating rod, 1a
...Groove, 2...Electric motor.

Claims (3)

[Claims] Claim 1: In a method of manufacturing a concrete member by pouring concrete into a formwork, a rotary member having a length corresponding to the depth of the concrete member is placed in the concrete on the surface side of the concrete member before it hardens. insert the rod,
A method for removing air bubbles from concrete members, in which air bubbles generated on the surface of the concrete are lifted and removed by rotating the concrete member and moving it along the formwork surface. 2. The method for removing bubbles from a concrete member according to claim 1, wherein the concrete is compaction-free concrete that does not require compaction by vibration. 3. The method for removing air bubbles from a concrete member according to claim 1 or 2, wherein a spiral groove is continuously formed on the circumferential surface of the rotating rod.