JPS61122322A - Method of destroying cast-in-place concrete pile head - Google Patents

Abstract

PURPOSE:To facilitate destroying of extra-banking concrete, by a method wherein a pipe filled with an expandable crushing agent is buried in the boundary of pile head of a cast-in-place pile, and surplus water is absorbed through pores for water penetration previously formed in the pipe. CONSTITUTION:After a pipe 1 is filled with an expandable crushing agent, the pipe 1 is banded to the inner side of a reinforcement cage 3 along the extra banking concrete cutting estimating line of a pile, and ready mixed concrete is poured to form a cast-in-place pile. In which case, surplus water in concrete penetrates into the pipe 1 through pores 2 for water penetration previously formed in the pipe 1, and the expandable crushing agent is gradually expanded as it performs water absorbing reaction. This enables the extra banking concrete of the pile head to be destroyed gently and as scheduled.

Description

[Detailed Description of the Invention] [Industrial Field of Application 1] The present invention is a method of counter-head fracture that can be easily carried out by systematically generating rips in the concrete portion of the pile head of a cast-in-place concrete pile. It is about the method.

[Conventional technology J Conventionally, the main method for destroying pile head reinforcement concrete of cast-in-place concrete piles has been manual methods using a bik etc. A method of burying the material in advance in the casing to be cut, and filling it with a slurry of an expandable crushing agent to destroy it (VF 1982-204216, JP 59-9
1214).

[Problem to be solved by the invention J Among these methods, the manual method using a pick etc. generates significant noise and dust, which causes pollution in urban areas, and also poses a threat to the safety of workers. There are hygiene issues.

The method of filling a slurry of expandable crushing agent can suppress the generation of noise and dust, but it is necessary to maintain the fluidity of the slurry constant during operation, which makes it difficult to control the amount of water and manage the mixing process. The work is complicated, as it requires sufficient

Therefore, there is a need for a method for crushing the head of cast-in-place concrete using an expansive crushing agent that does not involve complicated management of water volume and mixing of crushing agents, and the present invention is intended to overcome such conventional methods. The purpose of this invention is to provide a method for destroying cast-in-place concrete bedheads that solves the drawbacks of.

[Means for Solving the Problems] The present invention solves the above-mentioned problems by filling a pipe with a large number of permeable small holes with a powdered or granular crushing agent and dispersing it along the boundary line of the fractured bed head. This can be solved by installing it near the periphery.

That is, this invention installs a pipe filled with a powder or granular expandable crushing agent along the boundary line of the fractured pile head of cast-in-place concrete so as to almost surround the vicinity thereof, and after concrete is poured. , characterized in that by absorbing excess water in the concrete through small permeable holes previously provided in the pipe, the expandable crushing agent in the pipe reacts and develops expansion pressure, destroying the bed head fracture part. This is a method of destroying cast-in-place concrete pile heads.

! l [Function 1] To carry out this invention, first, a pipe (for example, a spiral sheath pipe) is filled with an expanding crushing agent (for example, Onoda Cement registered trademark: Plaister), and then this pipe is
As shown in the figure, the reinforcing bars are attached to the inside of the reinforcing bars along or slightly above the expected cut line of the concrete pile with reinforcing bars using binding wires, and then the ready-mixed concrete is set in place. to form concrete piles. At this time, the surface of the reinforcing bars above the concrete cutting line is covered with vinyl or plastic to make it easier to separate from the concrete. Excess water in the concrete is supplied to the expandable crushing agent filled inside the pipe through the holes, causing a water-use reaction, which generates expansion pressure and allows cracks to occur in a planned manner at the planned cutting line of the head of the bed. Depending on the diameter of the reinforcing steel, the pipe should be cut approximately 5 to 50 degrees below the planned cutting line of the additional concrete.
Preferably, it is placed above the 10c-position.

As the expanding crushing agent used in this invention, in addition to the above-mentioned price goo, various publicly known commercially available static expanding crushing agents in the form of powder or granules can be used. The ingredients are adjusted by retardants, etc.!
! It is desirable that the expansion pressure development time is adjusted.

As the pipe, a PC inlet pipe is suitable, but various other materials other than plastic having the same strength can be used. The diameter of the pipe is preferably 30 to 60 rings. The holes for water permeation provided in the pipe are φ 0.5 = 2. 5s
/Shizu, preferably (is φ 1.0~1.5 -/
The floor is good, the number of holes is 1 to 10 holes per 1 cm2 of pipe,
Preferably, the number of holes is 4 to 6. FIG. 1 shows a perspective view of a PC sheath inlet tube provided with holes for water permeation.

To fill a pipe with an expandable crushing agent, for example, the pipe is made into a semicircular shape, one end is closed, a predetermined amount of crushing agent is filled, the other end is closed, and the pipe is installed in a circular shape at a predetermined position. The pipe may be further divided and installed in the same way, and if necessary, multiple pipes filled with an expansive crushing agent can be connected vertically to reinforcing bars to prevent splitting of the concrete. You may go.

The amount of water supplied from the concrete can be adjusted by adjusting the diameter and diameter of the hole drilled in the inlet pipe, and can be made approximately equal to the amount required for the hydration reaction of the expansive crushing agent.
It is also possible to almost prevent powder from flowing out. .

[Example] The present invention will be explained below based on Examples.

Example 1 A PC sheath tube with a diameter of 40 mm and a wall thickness of 0.3 ml was provided with 5 holes of 1 mm per IC-2, and these were cut to be approximately equal to the circumferential length of the reinforcing bar. to make a semicircular shape,
One end is closed, and powdered Plyster, which is an expandable crushing agent, is filled until it is full and the cage is placed. At this time,
There is no need for vibration, tamping, compaction, etc., just let it flow naturally. Next, add this to φ1200＋*/+
Attach the piles marked with * to the inside of the reinforcing bars along the cutting line of the pile head using binding wire.

Plyster develops expansion pressure in accordance with the strength development of concrete, which is OKg7Cm in 1 day and 100 in 2.4 days.
Kg/c", 180 Kg/c in 5 days. When excavating 7 days after concrete was poured, a stub with a width of 3 to 5 a/m was found along the planned cutting line. This caused one part of the pile 1ij to be cut off.

Example 2 Three φ2.5 ugly/ugly holes per 1 am were installed in a PC sheath pipe with a diameter of 40 mm/-1 and a wall thickness of 0.3 II/- (this is the circumferential length of a reinforcing bar cage). Cut almost equally, close one end, fill it with granular Plaister, which is an expandable crushing agent, and cover it. and attach it to the inside of the reinforcing bar cage with binding wire.

Granular plyster has a particle size range of 0,3 s/min to 5
゜0-7-1 High ground weight 2.0 to 2.7 is best, and the development of expansion pressure is 0 g/am'' in 1 day, and 100 K in 4 days.
g/am 2.5 days and 180 g/as" was used.

Excavation will be carried out 7 days after concrete is poured.
"to"ゞ・cutting line 1: along・1 width 2~4"/
``1'' occurred and the head of the pillow had to be severed.

1 Effect of the invention 1 According to the present invention, an expanding crushing agent in the form of powder or W1 granules is used, and expansion pressure is developed by reacting the crushing agent with excess water in the concrete. It requires no management, is easy to operate, and can statically and systematically destroy the leftover concrete at the head of the bed.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a PC sheath inlet pipe used in carrying out the present invention, and Fig. 2 is a perspective view of the PCC sheath inlet pipe shown in Fig. 1 installed inside a reinforcing bar cage in an embodiment. In the diagram, 1...PC seam entry pipe, 2...hole, 3...reinforcement bar. In each figure, the same reference numerals indicate the same or corresponding parts. Patent Applicant Onoda Cement Co., Ltd. Sale 1 Drawing Proceedings Amendment Statement March 28, 1985

Claims (1)

[Claims] A pipe filled with a powder or granular expandable crushing agent is installed along the boundary line of the failed pile head of the cast-in-place concrete so as to almost surround the area, and after pouring the concrete, the pipe is pre-filled. Cast-in-place concrete characterized in that by absorbing excess water in the concrete through small permeable holes, the expandable crushing agent in the pipe reacts and develops expansion pressure, destroying the pile cap destruction part. How to destroy pile caps.