JPS605927A - Reinforcement for concrete structure to be affected by sea water - Google Patents

Abstract

PURPOSE:To raise corrosion resistance to sea water of a concrete structure by providing the agglutination layer of an Fe alloy with at least one of Al, Zn, Si, Zr, Ti, Mo and Ni on the surface of a round steel bar material and also an aluminium diffusion-impregnation layer in the inside of the round steel bar material. CONSTITUTION:The agglutination layer of an Fe alloy with at least one of Al, Zn, Si, Zr, Ti, Mo and Ni is provided on the surface of a reinforcement, e.g., round steel bar, etc., for concrete by powder method, gas method, salt bath method, paste method, etc. Also, an aluminium-diffusion-impregnated layer in the Fe base of the reinforcement. A high corrosion resistance as well as a high wear resistance, a high delaminating and breaking resistance, and a high sea water resistance can be endowed to the reinforcement.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a Σconcrete structure blocky rock structure object 9 artificial fish - 9 bridge girder, chemical factory under the influence of seawater.

Seawater storage tanks, etc. are used in these concrete structures, and concrete round steel bars, deformed reinforcing bars, set reinforcing bars, and iron pieces are used to reinforce the concrete strength.

Reinforcing members for concrete such as iron bars and hanging metal fittings, and connecting members buried in and/or attached to concrete to connect concrete blocks such as bolts and nuts (hereinafter, the above-mentioned reinforcing members for concrete and connecting members are collectively referred to simply as reinforcement) (referred to as members) are used.

However, the concrete in which the reinforcing members are used is exposed to sea waves while in contact with seawater or exposed to sea breezes containing seawater spray.

Caused by tidal currents, wind power, or vehicles passing over concrete bridges. Cracks occur due to the vibrations, and salt water infiltrates through the cracks, causing the concrete reinforcing member to spin. It is also said that the chemical reaction between seawater and the concrete surface material deteriorates the concrete surface, making it easier for seawater to enter, leading to similar results in many cases.

Furthermore, since such rusting is accompanied by volumetric expansion, the minute cracks that initially occur are gradually enlarged and eventually lead to the collapse of the concrete structure.

For this reason, steel for reinforced concrete used in the atmosphere has a service life of 30 to 50 years, but it is used in the atmosphere near the sea surface, in the sea at all times, and in the splash zone in between. Steel materials for reinforced concrete are said to have a shorter lifespan than normal in the atmosphere. Particularly in the splash zone, the amount of dissolved oxygen in seawater is high, and the above deterioration process is accelerated by salt and oxygen, resulting in severe oxidation corrosion of steel parts buried in concrete, especially in concrete for fish reefs. The anchor bolts and nuts used become unusable after two to three years.

However, it is economically difficult to use materials with excellent seawater resistance, such as stainless steel, as reinforcing members.
At
Aluminized steel, sierra-dized steel, etc. with a plating layer of Zn or the like have been tried, but since the plating layer has weak adhesion to the steel base and low hardness, such metal-coated steel is used as a reinforcing material in concrete. The aluminum and zinc plating layers may be peeled off or damaged during concrete pouring or vibrating construction, and even if they are peeled off during vibrating construction.

Even if they were spared from damage, they still had the drawback that when seawater entered, corrosion would begin at the surface and the plating layer would peel off and wear out. Another disadvantage was that long-term vibrations caused by waves and currents caused similar results.

The present invention eliminates the drawbacks of conventional reinforcing materials for concrete structures that are affected by seawater.

It is an object of the present invention to provide an improved reinforcing member, and this object can be achieved by providing a reinforcing member as described in the claims. That is, the present invention provides a reinforcing member for concrete structures that is affected by seawater, and the reinforcing member has a surface of Az+Zn+O.
rr 8L Tit This is a reinforcing member for concrete structures that is affected by seawater and is made by diffusion coating a steel material made of at least one metal selected from Zr+Mo+Ni. It is a reinforcing member that can protect against influences.

Next, the present invention will be explained in detail.

The reinforcing member of the present invention is one in which the metal is diffused and coated on the surface of the leaf part. For example, a member diffused and coated with M has an adhesion layer of an alloy made of Fe-Al on the surface with a thickness of 5 to 200 μm. Further, a permeation layer with a thickness of 3 to 50 μm is formed in which the Fe matrix is diffused into the Fe matrix. In addition to the above At, metals such as Zn+ Or, Si, Ti, or kl-8LAI.

- It is also possible to make a reinforcing member by diffusion coating using metal mixed powder or alloy such as Zn, Cr-8i, Cr-Ti, etc. As in the case of Asahi, the bonding layer and the penetration layer are made of each metal. Formed.

A as the metal to be permeated and diffused in the reinforcing member of the present invention
t, + Zn+ Cr, st, Zr+ Tit M
The reason for using at least one selected from o+Ni is that the adhesion layer and permeation layer made of these metals have a high degree of corrosion resistance, and have a hardness of 2.0% compared to a cable member not coated with a diffusion coating. ~6 times higher, not only has excellent abrasion resistance and peeling resistance during concrete pouring, but also does not easily peel off and damage when seawater enters.
Waves received during long-term use.

This is because it is not easily peeled off or damaged by vibrations caused by tidal currents, vehicles, etc.

In the reinforcing member of the present invention, even if the adhesive layer on the temporary sheet is partially peeled off during use, a permeable layer is formed on the surface of the base material, and this has excellent corrosion resistance and abrasion resistance, so it will last for many years. can withstand use.

Next, a diffusion coating method for manufacturing the reinforcing member of the present invention will be explained.

Diffusion coating methods can be roughly divided into four types: powder method,
They are gas method, salt bath method and paste method.

In the powder method, the desired metal is made into a powder by itself, or if this is difficult, it is made into a molten alloy with Fe, and then pulverized to make a powder. The powder is called an alloying agent or a penetrating agent, and is heat treated with a halide as a flux to complete the diffusion coating. In the gas method, the desired metal is turned into a halogen gas and flows into a furnace in a non-oxidizing atmosphere, and is heated in the furnace to form a diffusion coating.

In the salt bath method, the desired metal salts are applied, heated and melted, and the workpiece is inserted into the crucible and diffused.

In the paste method, the desired metal is powdered, mixed with a binder such as CMC to form a paste, applied to the surface of the workpiece, and then heated and diffused in a furnace.

Among the four types of diffusion coating methods described above, in many cases, the powder method is suitable for manufacturing the reinforcing member of the present invention from the viewpoint of the shape and dimensions of the member.

According to this method, powder of the metal or alloy to be diffused, a small amount of ammonium chloride, and an anti-sintering agent are placed in an iron case along with the raw materials at intervals so that the raw materials do not come into contact with each other. By hardening and heating the case so that as little air as possible remains inside the case, the metal or alloy is coated and adhered to the raw material as an adhesion layer and a diffusion layer.

Next, an example of a reinforcing member manufactured by a powder method will be described.

Example 1 Length in, diameter 38 mm hardness 1 (v (2009) 1
Metal powder 10 is made by blending Zn, Cr+A-t powders with 22 round steel bars at a weight ratio of 8027:13.
The buried iron case was heat-treated at 670C for 1.5 hours in a treatment agent containing 3 parts by weight of NH4C1 in 0 parts by weight to obtain a reinforcing member with a surface hardness of Hv (2009) 510.

The concrete is vibrated on this reinforcing member and one side of the concrete is 20cm x 20CI+! A concrete structure with a corner and a length of 1m was manufactured. No abnormalities were found when the structural members were destroyed and the reinforcing members were inspected. Furthermore, a concrete structure manufactured in the same manner was vibrated with a vibrator for 100 hours, and as a result, cracks appeared in the concrete, but the bonding layer of the members buried inside was not peeled off or damaged.

For comparison, a vibration test was conducted on the round steel bar plated with hot-dip aluminum and concrete was placed in the same manner as above, and the plated layer was found to have partially peeled off.

Example 2 Length IWL, diameter 32mm hardness Hv (2009>12
NH was added to 100 parts by weight of a compound prepared by blending Zn 80:Fe 20 alloy powder and Fe 50ζ 5150 alloy powder in a weight ratio of 80 to 20.
As a result of adding 3 parts by weight of 4Ct and performing heat treatment at 640C for 1.5 hours, a reinforcing member with a hardness of Hv (200) 280 was obtained.

The reinforcing member thus obtained was immersed in 5% salt water for 24 hours and then exposed to the atmosphere in mM for 60 consecutive days, but no rusting occurred.

As described above, the reinforcing member of the present invention has higher hardness than aluminized steel and Sierra-dized steel, has good wear resistance, and has excellent corrosion resistance. Since no peeling of the permeable layer has been observed, it is expected that if buried in concrete structures that are affected by seawater, it will be possible to protect concrete structures for many years.

Patent applicant: Japan Heavy and Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. In a reinforcing member for concrete structures that is affected by seawater, the surface of the reinforcing member is Az+Zn+
A reinforcing member for concrete structures that is affected by seawater and is made of a steel material made of at least one metal selected from Cr+Si+TL, Zr+Mo+Ni, and diffused by diffusion waves.