JP3131897B2 - Method of preventing defects due to concrete sedimentation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing cast concrete from causing defects such as cracks around reinforcing bars due to settling thereof.

[0002]

2. Description of the Related Art In ordinary concrete, sedimentation of particles in concrete occurs up to about 4 hours after casting due to material separation such as breathing. This phenomenon occurs in the entire concrete. However, if the sedimentation is locally inhibited by the presence of the reinforcing steel, the concrete on the upper part of the reinforcing steel, etc. cannot sink, and internal defects such as cracks occur around the reinforcing steel.

For example, in a pier, as shown in FIG. 6, a “paragraph” is performed on a part of the longitudinal reinforcing bars 1 in the height direction of the pier 2. In the conventional case, the top of the vertical reinforcing bar 1 is a flat surface as shown in FIG. 7, so that the surrounding concrete deviating from the top flat surface 3 sinks, whereas the top of the vertical reinforcing bar 1 is directly above the top flat surface 3. Since the concrete is inhibited from settling, a settling difference is generated. When the settling difference is large, a crack 4 is generated around the top plane 3. Since such cracks 4 are apt to be concentrated and generated in the section as a paragraph, when the pier 2 receives seismic force, there is a problem that as shown in FIG. there were.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to minimize the above-mentioned inhibition of concrete settling by a reinforcing bar, thereby preventing defects such as cracks due to the difference in concrete settling.

[0005]

The method according to the present invention is characterized in that concrete is poured with the top of a reinforcing bar buried in concrete tapered, and the sedimentation difference of the concrete around the top of the reinforcing bar is reduced. And In the case of a longitudinal reinforcing bar, a conical cap is attached to the top, or the top of the reinforcing bar itself is conical. In the case of a lateral reinforcing bar, the top of the cross section of the reinforcing bar is tapered.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a case where a reinforcing bar buried in concrete is a vertical reinforcing bar 10. In this case, a conical cap 11 is detachably attached to the top of the vertical reinforcing bar 10, and concrete is cast to embed the reinforcing bar 10 including the conical cap 11. Since the top of the reinforcing bar 10 is tapered by the conical cap 11, the difference in sedimentation of the concrete around it is reduced, and cracks and the like due to the difference in sedimentation can be prevented. Conical cap 11
If a relatively soft metal such as lead or aluminum is selected as the material of the rebar 10, it is easy to attach the conical cap 11 to the top of the reinforcing bar 10 by fitting. If the surface of the conical cap 11 is colored, it is easy to visually check whether or not the cap has been attached.

FIGS. 2 and 3 show a longitudinal reinforcing bar 1.
The top of 2 is processed into a conical shape and concrete is poured. In FIG. 2, the top end of the reinforcing bar 12 is sharpened, but in FIG. 3, the top end is rounded in consideration of work safety. Another consideration for work safety is to prepare a safety cap made of plastic, cover it with the top of the reinforcing bar 12, arrange the reinforcing bar 12, and remove it immediately before placing concrete. Conceivable.

The example shown in FIGS. 4 and 5 shows a horizontal reinforcing bar 13.
In FIG. 4, the cross-sectional shape of the reinforcing bar 13 is made elliptical,
In FIG. 5, since the upper and lower ends are formed into a flat plate shape, sedimentation inhibition around the reinforcing bar 13 with respect to concrete is reduced, and the adhesion of the reinforcing bar 13 is increased.

[0009]

According to the present invention, the sedimentation difference of concrete around the top of the reinforcing bar can be reduced, and the following effects are obtained. It is possible to suppress the occurrence of shear cracks from the rebar paragraph. It is possible to avoid a sudden change in the amount of steel in the reinforcing bar section. It is possible to increase the concrete adhesion of the lateral reinforcing bar. The durability of the lateral reinforcing bar can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a longitudinal reinforcing bar used in a first example of the present invention.

FIG. 2 is a perspective view of a longitudinal reinforcing bar used in a second example of the present invention.

FIG. 3 is a perspective view of a longitudinal reinforcing bar used in a third example of the present invention.

FIG. 4 is a perspective view of a lateral reinforcing bar used in a fourth example of the present invention.

FIG. 5 is a perspective view of a lateral reinforcing bar used in a fifth example of the present invention.

FIG. 6 is a schematic sectional view of a reinforcing bar paragraph section of a pier.

FIG. 7 is an enlarged cross-sectional view of a part of FIG. 6, and also shows a conventional longitudinal reinforcing bar used for a paragraph section.

FIG. 8 is a schematic view showing that a shear crack is generated from the reinforcing bar paragraph.

[Explanation of symbols]

 10.12 Longitudinal reinforcement 11 Conical cap 13 Lateral reinforcement

Claims (4)

(57) [Claims] An object of the present invention is to prevent a defect due to concrete sedimentation phenomena, wherein concrete is cast with the top of a reinforcing bar buried in the concrete tapered to reduce the difference in sedimentation of the concrete around the top of the reinforcing bar. Method. 2. The method according to claim 1, wherein the concrete is cast with a conical cap attached to the top of the vertical reinforcing bar. 3. The method according to claim 1, wherein the concrete is cast with the top of the reinforcing bar in a vertical direction being conical. 4. The method according to claim 1, wherein the concrete is cast with the top of the cross section of the lateral reinforcing bar tapered.