JP2705007B2 - High-strength concrete structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete structure such as a pillar, a beam, a pile, etc., and more particularly to a high-strength concrete structure in which a reinforcing bar does not rust.

[0002]

2. Description of the Related Art In a structure such as a pillar, a beam, a pile, and the like, which is to be a trunk of a structure in a building structure or a civil engineering structure, a reinforcing bar is arranged inside and concrete around which aggregate is mixed with cement is poured. Is generally adopted.

[0003]

A problem that has recently become a problem in these structures is salt damage caused by the use of sea sand. In other words, when sea sand is used as a concrete aggregate, the sand is not sufficiently washed, so that the reinforcing steel arranged as reinforcing steel rusts. Also, it has begun to be known that acid rain and an increase in carbon dioxide in the air gradually come into contact with the structure to neutralize the concrete, which also causes the internal reinforcing steel to rust. In addition, in the case of marine structures and underground structures, a large cover is used to prevent rusting of the reinforcing steel, but this is very uneconomical in design.

[0004] As a countermeasure, in order to prevent the rebar from being affected by salt damage and the like, an attempt was made to use stainless steel as the rebar. Trials were also made for the coating, but there was a problem of lack of reliability.

The present invention has been made to solve the above problems, and provides a high-strength concrete structure which can be economically constructed without being affected by salt or acid rain in concrete. The purpose is to:

[0006]

SUMMARY OF THE INVENTION A high-strength concrete structure according to the present invention uses a stainless steel sheath. The stainless steel sheath is a thin-walled cylindrical sheath made of stainless steel, and has a spiral shape on its peripheral surface. Concavities and convexities are continuously formed in a shape. A deformed reinforcing bar having irregularities on the peripheral surface is arranged in the stainless sheath. The deformed reinforcing bar in the stainless sheath may be singular or plural. A cement-based hardening material such as a cement paste or mortar kneaded with fresh water is injected into the stainless steel sheath and hardened. In this way, the deformed reinforcing bar and the sheath become a reinforcing bar united by the hardening material, and a plurality of these stainless sheaths are arranged at an appropriate interval, and the periphery thereof is surrounded by the band bar. As the stirrup, there are several ring-shaped ones,
They may be arranged at appropriate intervals, or may be spirally bent. Concrete is poured into the inside and the outer periphery surrounded by the stirrups to construct a structure. If the structure is a pillar or beam or a pile manufactured by a factory, concrete is poured around the stirrup with a formwork.If the pile is cast in place, a stainless steel sheath or The stirrups can be hung down and concrete can be cast.

[0007] Before placing the stainless steel sheath,
It is a method of integrating a reinforcing bar and a hardening material inside the sheath in a factory, etc., and using it as a single reinforced body, but after arranging it at the appropriate position for use on columns and piles at the site or factory, the hardening material May be injected.

[0008] A secondary kneading material is sometimes used as a cement-based hardening material injected into a stainless steel sheath. Primary water and a water reducing agent are added to the cement to perform primary kneading at a water-cement ratio of 17 to 35%, and then secondary water is added and secondary kneaded to a total water-cement ratio of 28 to 48% to cure. Material.

[0009]

[Function] Since the cement hardening material in the stainless steel sheath is kneaded with fresh water, the deformed reinforcing bar does not rust. The stainless steel sheath blocks out the salt in the surrounding concrete, so there is no effect on deformed rebar. The secondary kneaded hardened cement hardly generates bleeding water and does not affect the adhesion of the reinforcing steel.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the drawings. The embodiment is an embodiment in which the present invention is implemented in a pillar. In the figure, reference numeral 1 denotes a stainless steel sheath, in which a plurality of deformed reinforcing bars 2 are arranged. Occasionally, more than ten deformed reinforcing bars 2 are inserted into the sheath 1. One or more of the stainless sheaths are appropriately erected so as to be located near the outer periphery of the column. A stirrup 3 is arranged so as to surround the stainless steel sheath 1. A ring-shaped reinforcing bar is arranged as the band bar 3.

A cement-based hardening material 4 is injected into the stainless steel sheath 1 and hardened. For injection, a hose 7 previously arranged in the sheath 1 is used, and the hardening material 4 is filled so as to push up from the lower end of the sheath 1 whose lower end is sealed.
The hose 7 may be pulled out or left. The cement-based hardening material 4 employs a method in which water to be added is divided into two times. As the water, fresh water, that is, water that does not contain any salt, is carefully used. The results of Experiments 1 to 7 are shown in Table 1 below.

[0012]

[Table 1]

In Experiments 1 to 6, experiments were conducted in which a water reducing agent was added during the primary kneading and an experiment in which the water reducing agent was added during the secondary kneading. You can see that Referring to the results of Experiments 1 to 7, good results are obtained when the water-cement ratio is 17 to 35% during the primary kneading. Good results are obtained when the final water cement ratio is 28 to 48%. The cement-based hardening material 4 adjusted in this range is poured into the stainless steel sheath 1 as a paste and hardened.

A form 5 is arranged so as to further surround the stirrup 3, and concrete 6 is cast. As the concrete 6, sea sand may be used. Concrete 6
After curing, the mold 5 is removed.

In the above embodiment, the present invention is applied to the construction of a pillar. However, the present invention can be applied to various structures such as a beam and an underground pile. Also, the cross section of the structure is not limited to a square or a polygon, and can be implemented in various shapes such as a circle and an ellipse.

[0016]

The present invention has the above-described configuration, and can obtain the following effects. Since a cement-based hardening material obtained by kneading cement and an admixture with fresh water was injected around the deformed reinforcing bar, a substance that generates rust is not included, and the durability is high. Even if the concrete around the stainless sheath is made of sea sand and contains salt or is neutralized by carbon dioxide, rainwater and carbon dioxide are blocked by the stainless sheath, so that the rust prevention effect is significantly improved. Since the deformed rebar is protected by the stainless steel sheath, it does not rust even if the rebar is positioned near the outside of the structure and the cover is made small.
A portion having a cover of 0 cm or more can be reduced to several cm, and there is no waste in design. It is clear from experiments and large earthquake disasters that the reinforcing bars arranged individually are buckled when a large compressive force is applied. Experiments have shown that buckling resistance is significantly improved when relatively thin reinforcing bars are bundled and constrained by this sheath. The use significantly improves the durability of the structure. Bundling and using even relatively thin reinforcing bars is advantageous in terms of adhesion of grout and concrete, and the cracks are finely dispersed, so that harmful cracks can be prevented. The deformed reinforcing bar has a large diameter due to a stainless steel sheath, and has irregularities formed on its peripheral surface, and is attached so as to mesh with the surrounding concrete, so that a high bending strength can be obtained. By using a cement-based hardening material kneaded by adding fresh water in two parts, it is difficult for breathing water to be generated in the stainless steel sheath, and a strong reinforcing member in which the deformed reinforcing bar, the hardening material, and the stainless steel sheath are integrated And the proof stress of the structure is improved. In particular, in the case of a beam, breathing water accumulates in the upper portion of the cross section of the horizontal sheath, weakening the binding force between the reinforcing bar and the hardening material by the sheath and easily losing durability. If a cement-based hardening material is used, there is no generation of breathing water and the durability is not impaired. The stainless sheath used in the present invention can sufficiently compensate for defects such as breakage of the polyethylene sheath during handling and low grout restraining force.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment when a pillar is constructed.

FIG. 2 is a sectional view thereof.

FIG. 3 is a sectional view of a stainless steel sheath.

FIG. 4 is a cross-sectional view showing a state where a hardening material is injected into a stainless steel sheath.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless sheath 2 Deformed bar 3 Stud 4 Cement hardening material 5 Formwork 6 Concrete 7 Hose

Claims (3)

(57) [Claims] A stainless steel sheath having irregularities on its peripheral surface is provided with one or more deformed reinforcing bars, and a cement-based hardening material is injected into the sheath and hardened.
A high-strength concrete structure constructed by arranging a plurality of these stainless steel sheaths, which are reinforced bodies, at appropriate intervals and surrounding them with a stirrup, and casting concrete on the inside and the outer periphery surrounded by the stirrups. 2. A stainless steel sheath having irregularities on its peripheral surface is provided with one or a plurality of deformed reinforcing bars, and a plurality of stainless steel sheaths are arranged at appropriate intervals and surrounded by a band. A high-strength concrete structure constructed by injecting a cement-based hardening material into the interior of these stainless steel sheaths and casting concrete on the inside surrounded by the stirrup and the outer periphery. 3. The primary water and the water reducing agent are added to the cement to perform primary kneading at a water cement ratio of 17 to 35%, and then secondary water is added to the cement to obtain a total water cement ratio of 28 to 48%. The high-strength concrete structure according to claim 1, wherein a cement-based hardening material obtained by kneading is injected into a stainless steel sheath.