JP2000054650A - Method for cutting reinforcing bar in concrete structure to be demolishled - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cutting a reinforcing bar in a concrete structure to be demolished with small noise and preferably less labor. SOLUTION: A first hole 14 and a second hole 16 are provided in a concrete structure 10 to be assembled so as to get from both upper and lower positions on its surface to two upper and lower positions 20, 22 adjacent to each other on an inside bar 12 and then thermit 24 is filled in the first hole and ignited. Part of the bar is melted with the reaction heat of the thermit and thermally molten material as the part of the bar is discharged from the melt position through the second hole 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a reinforcing bar in a concrete structure, which is used for dismantling the structure.

[0002]

2. Description of the Related Art In order to facilitate dismantling work of a concrete structure, a reinforcing bar in the structure has been cut in advance.

Conventionally, the cutting of a reinforcing bar is performed by providing a relatively large-diameter hole which reaches the reinforcing bar from the surface of the building and further goes around the back side of the reinforcing bar. This was done by fusing the rebar.

[0004] However, this method has a problem that cutting of the rebar involves dust and noise and requires labor.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for cutting a reinforcing steel bar of a concrete structure to be demolished with low noise, more preferably without generating dust and with less labor. is there.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a concrete structure is constructed such that first and second positions are respectively reached from upper and lower positions on the surface of a concrete structure to upper and lower positions of a reinforcing bar inside the concrete structure.
Providing a first hole and a second hole, filling the first hole with a thermite, and then igniting the thermite.

[0007]

According to the present invention, a part of the reinforcing steel in the building can be melted by the heat generated by igniting the thermite filled in the first hole. Thermal melting of a portion of the rebar occurs at a location where the first hole reaches the rebar. Since the reaching position of the second hole with respect to the reinforcing bar is at a lower position adjacent to the reaching position of the first hole, a part of the hot melt of the reinforcing bar flows into the second hole, and further, The second
Can flow down towards the surface of the construct. As a result, a part of the molten material of the rebar is removed from the molten portion, and the rebar can be reliably cut by thermal melting.

[0008] No special mechanical equipment or labor is required for filling the thermit required for cutting the rebar, hot-melting the rebar and removing the hot-melt, and also generates noise and dust. Absent.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, there is shown a portion of a concrete structure to be demolished, for example, a portion of a concrete wall 10, to which the present invention is applied.

The wall 10 has a concrete portion 11 and a reinforcing bar 12 extending vertically through the concrete portion, and the reinforcing bar 12 is cut according to the present invention to facilitate the disassembly of the wall 10.

For cutting the reinforcing bar 12, first, 2
Holes 14 and 16 are provided.

The two holes 14 and 16 respectively correspond to the surface 1 of the wall.
8 reach two adjacent upper and lower portions 20 and 22 of the reinforcing bar 12 from both upper and lower positions.

More specifically, one hole (first hole) 14
Extends the concrete portion 11 obliquely downward from a position above the wall surface 18 toward an upper point 20 of the rebar 12,
The other hole (second hole) 16 extends the concrete portion 11 obliquely upward from a position below the wall surface 18 toward a lower portion 22 of the reinforcing bar 12. 22 is exposed.

The inclination angles of the holes 14, 16 can be arbitrarily determined. The holes 14 and 16 have a large diameter (for example, 30 mm) and a small diameter (for example, 15 m).
m), but it is optional to use one having the same diameter, or one having a small diameter and one having a large diameter.

The holes 14 and 16 can be formed, for example, by using a drilling device such as a diamond core drill, or by subjecting the concrete portion 11 to ultrasonic cutting. The latter ultrasonic cutting process is, for example, a sonodrill SS1-50 manufactured by Taga Electric Co., Ltd.
This can be done with a perforator designated as 0. When ultrasonic cutting is performed, the level of noise, vibration, and dust generation during drilling is significantly lower than when drilling using the diamond core drill.

After the formation of the holes 14, 16, the first hole 14 is filled with a thermite (a mixture of ferric oxide and aluminum powder) 24. The filling operation can be performed easily and in a short time by lightly squeezing the thermite with a ram. At this time, the thermite 24 contacts the exposed upper part 20 of the reinforcing bar 12. The first hole 14 extending obliquely downward toward the reinforcing bar 12 holds the filled thermite 24 so that it does not spill.

When filling the thermite 24, thermit 2
Of the ignition device 26 for igniting the
4 buried inside. The ignition device 26 includes a resistance wire (for example, an iron wire having a thickness of about 0.2 mm) buried in the thermite 24 and a power source 30 disposed outside the first hole 14.
And a switch 32 and a conductor 3 connecting them in series
4 Other known ignition devices, such as magnesium ribbon, can be selected as the ignition device.

When the switch 32 is turned on and a current flows through the resistance wire 28, the resistance wire 28 is heated and the thermite 24 is ignited. This causes thermite 24 to undergo an exothermic reaction,
The exothermic temperature reaches about 3100 ° C. Due to the heat generated by the thermite 24, a part 20 of the reinforcing bar having a melting point of 1535 ° C., which is in contact with the thermite 24, is thermally melted.

Since the second hole 16 is open immediately below the heat-melted portion of the part 20 of the reinforcing bar, the second hole 16 is opened.
Flows into the second hole 16. Furthermore, the second
The hole 16 extends obliquely downwardly toward the wall surface 18 so that the hot melt flows down in the second hole 16 and flows out of it. In this way, the hot melt is completely removed from the melting point without remaining at the melting point. Therefore, after ignition of thermite 24,
The cutting (melting) of the part 20 of the rebar can be completed without adding an artificial operation.

[Brief description of the drawings]

FIG. 1 is provided on a construct to carry out the present invention;
FIG. 3 is a longitudinal sectional view of a first hole and a second hole of thermit filling.

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wall (part of a structure) 12 Reinforcement 14, 16 1st hole and 2nd hole 18 Surface of wall 20, 22 Above and below rebar 24 Termite

Claims (1)

[Claims] 1. A method of cutting a reinforcing bar in a building for dismantling a concrete structure, wherein the building reaches two adjacent upper and lower positions of the reinforcing bar from both upper and lower positions on a surface of the building. A method for cutting a reinforcing bar, comprising: providing a first hole and a second hole; filling the first hole with a thermite; and igniting the thermite.