JP3361348B2 - Concrete modification method - 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 reforming concrete in which concrete containing a steel material is electrochemically treated.

[0002]

[Prior art and its problems] Concrete is generally
Due to its strong resistance to various environments and its strong alkalinity, the steel material inside it is protected from corrosion by forming a passivation film on the steel surface, which makes the concrete structure durable. It has been considered to be a permanent structure.

However, the durability of the concrete structure, which has been considered to be the permanent structure, is deteriorated due to causes such as neutralization and salt damage, and the life of the structure has been questioned. .

Generally, inside hardened concrete,
Saturated calcium hydroxide aqueous solution is sufficiently present as pore water. Therefore, when an electric current is applied to the concrete, the pore water acts as an electrolyte, and an electric current corresponding to the resistance of the concrete itself flows.

Further, a method is preferred in which an electrolyte solution is further applied to the hardened concrete to facilitate the flow of an electric current,
It is usually done.

In this way, as a method for repairing a deteriorated concrete structure, the surface of the concrete is temporarily coated with an adhesive coating material consisting of an electrolyte solution and cellulose fibers, and electrodes are embedded in the coating material. A direct current is passed between the internal rebar of the concrete and this electrode, which causes chloride ions to migrate from inside the concrete towards the electrode and remove it from the concrete, which in turn removes the electrode and coating material. A repair method using a chemical method was proposed (Japanese Patent Laid-Open No. 2-30238).
(Gazette No. 4).

[0007] However, in this method, the electrodes installed on the concrete surface are covered by spraying the cellulose fibers and the electrolyte solution, so that the cellulose fibers are scattered around during the spraying work, thus contaminating the surrounding environment. As a result, or because an alkaline solution is usually used as the electrolyte solution, the solution may scatter during spraying, which not only pollutes the surroundings but also causes injury etc. if it touches the eyes or skin of workers. There were problems such as being there.

The inventors of the present invention have conducted various studies in order to solve such problems, and as a result, by adopting a specific method, the above problems can be solved and the concrete structure can be sufficiently modified. The present invention has been completed based on the knowledge that it can be performed.

[0009]

[Means for Solving the Problems] That is, the present invention relates to a steel material inside concrete as an internal electrode, an electrode installed at one or more locations on the concrete surface as an external electrode, and a plate-shaped molding around the external electrode. things and / or the electrolyte solution holding material thickness 1~20cm consisting cloth-like material is placed, water and electrolytes
A method for modifying concrete, characterized in that the solution is supplied to the surface of the concrete in an appropriate amount and supplied, and an electric current is applied between the external electrodes and / or between the external electrode and the internal electrode. Is a water-absorbing substance and / or a swelling substance, and is a method for modifying concrete.

The present invention will be described in detail below.

In the present invention, the internal electrode is a steel material existing inside concrete, and may be a reinforcing bar, or a steel material specially installed in concrete can be used.

The external electrode used in the present invention is an electrode installed on the surface of concrete, and two or more external electrodes may be required depending on the state of the concrete to be modified. The distance between the external electrodes is not particularly limited as long as the current flows normally.

Further, it is preferable to use the external electrode fixed to the electrolyte solution holding material in advance, because the labor for installing the electrode on the concrete surface can be saved and the labor can be saved.

In the present invention, an electrolyte solution holding material composed of a plate-shaped molded product and / or a cloth-like substance is installed on the surface of concrete, and the electrolyte solution holding material holds the electrolyte solution. Contact.

The thickness of the electrolyte solution holding material of the present invention is not particularly limited, but is usually about 1 to 20 cm,
It is preferably about 1 to 10 cm.

The plate-shaped molded product is composed of concrete, cement, mortar, stone, tile, metal, resin, wood, cloth, paper, sponge, fiber, etc. as a component, and these may be used alone or in combination. It is molded. There is no limitation on the size and shape of the plate-shaped molded product, and it can be appropriately selected according to the purpose and work procedure. It should be noted that it is preferable to use a plate-shaped molded product that is processed into a shape along the surface of the corner or curved part of the concrete, from the viewpoint of improving workability.

Further, at least a part of the portion of the plate-shaped molded product which is in contact with concrete, it is necessary to make a material having a function of keeping the concrete in a wet state in order to improve the ability to retain the electrolyte solution.

Examples of the material include materials made of fibers such as wood and cloth, fibrous substances such as pulp and rock wool,
Water-absorbing or water-retaining materials such as water-absorbing polymers and swollen rubbers, porous materials or porous mesh materials such as sponges and pumice, hydraulic porous materials such as gypsum and cement, foam materials such as styrene foam and artificial lightweight aggregates, bentonite Gel-like substances such as can be used.

Further, these electrolyte solution holding materials may be temporary materials which are installed only during the modification treatment of concrete, but they can be left on the concrete surface as they are as finishing materials or protective materials. is there.

The cloth-like substance according to the present invention refers to a product obtained by weaving or knitting fibers or filaments, a product obtained by laminating fibers or filaments like non-woven fabric or paper, and the like. It also includes a combination of. A product obtained by weaving or knitting fibers or filaments is preferable because it helps the electrolyte solution to spread quickly along the weave or the stitch. Further, a laminate of fibers and filaments is preferable because it serves to retain the supplied electrolyte solution.

Here, the material of the fibers and filaments is not particularly limited, but inorganic fibers, organic fibers, metallic fibers and the like can be used. In particular, natural fibers and highly hydrophilic fibers can be used. Use is preferred.

Since the cloth-like substance is usually wound in a roll shape, when it is installed on the concrete surface, it can be installed by laying it on the concrete surface or hanging it only by fixing a part thereof. Further, since the cloth-like substance is flexible, it can be adhered to a curved or uneven concrete surface. Further, there is no limitation on the size and shape of the cloth-like substance, and the size and shape can be set according to the purpose and work procedure.

The water-absorbing substance according to the present invention is a substance which preserves water in the substance, and the water absorption capacity within 24 hours, that is, the ratio of the weight of water absorption to the weight of the substance is 10 or more. preferable. Specific examples of the water-absorbing substance include acrylic acid-based, polyacrylic acid-based, and acrylic acid / vinyl alcohol-based water-absorbent resins.

The swelling substance is a substance whose volume increases when it absorbs water or comes into contact with water.
It is preferable that the volume doubles within 24 hours. Specific examples of the swelling substance include swelling rubber and the like. Since the swelling substance expands in volume, it is possible to bring an electrolyte solution holding material composed of a plate-shaped molded product or a cloth-like substance into close contact with the concrete surface, and between the concrete surface and the electrolyte solution holding material. Being solid, the ability to retain the electrolyte solution on the concrete surface is increased.

These water-absorbing substances and swelling substances play a role of retaining water and electrolyte solution when they are present in excess, and supplying them when water and electrolyte solution are insufficient. . Therefore, it becomes possible to appropriately supply the electrolyte solution to the vicinity of the external electrode.

The amount of the water-absorbing substance and / or the swelling substance to be used varies greatly depending on the material used and is appropriately determined.

Further, when the supply of the electrolyte solution is stopped after the modification treatment of the concrete is completed, the water-absorbing substance and the swelling substance release the retained electrolyte solution and return to the original state. It becomes easy to remove the shaped objects and cloth-like substances from the concrete surface.

[0028]

EXAMPLES Hereinafter, examples will be described based on the present invention.

Example 1 About 30 years after construction, a test was conducted using a part of a reinforced concrete wall having a height of 4 m, a width of 40 m and a thickness of 35 cm, which contained a considerable amount of salt. First, this concrete is partially suspended, the reinforcing steel inside the concrete is used as an internal electrode, and further, as an electrolyte holding material, a non-woven fabric is attached to an acrylic plate with a thickness of 25 mm with a thickness of 50 mm, and the diameter of the non-woven fabric is 6 mm at intervals. An external electrode was formed by placing a plate-shaped molded product having a length of 1 m, a width of 2 m, and a thickness of 75 mm, in which a wire mesh of 10 cm was built-in, on the surface of concrete, and allowing the alkaline aqueous solution to soak into the surface. A direct current with a current density of 1.0 A / m ² was applied between the internal and external electrodes for 1 month,
After performing the desalting treatment, the plate-shaped molded product on the surface of the concrete was removed, the concrete was cored, and the amount of salt contained therein was measured.

As a result, the amount of salt content in the concrete was reduced to 10% or less before the treatment, and it was confirmed that the concrete was subjected to the reforming treatment. Further, since the plate-shaped molded product was used as the electrolyte holding material, no accident such as contamination of the surrounding environment or injury of workers occurred.

Example 2 A cloth-like substance in which a non-woven cloth made of cotton and having a thickness of 50 mm is sewn on one side, and a gauze is sewn on one side and a vinyl sheet for preventing drying is sewn on the other side. Then, the concrete wall was pressed in two places at 3.5m intervals, and fixed with plastic anchors. Then, a perforated pipe for absorbing water was installed on the lower surface of the square bar, the alkaline aqueous solution was passed over, and a certain amount of the electrolyte solution was supplied to the cloth-like substance. An elec- trode made by Eltec Asia Co., Ltd. under the trade name "Elgard mesh # 210" is used as an external electrode, and a direct current with a current density of 1.2A / m ² is applied for 2 months. The test was conducted in the same manner as in Example 1.

As a result, the amount of salt content in the concrete was reduced to 10% or less before the treatment, and it was confirmed that the concrete was subjected to the modification treatment. Furthermore, since a cloth-like substance is used as the electrolyte holding material, no accident such as contamination of the surrounding environment or injury of workers occurred.

Example 3 As the electrolyte holding material, a lightweight cellular concrete panel having a thickness of 75 mm and an ALC panel manufactured by Iton Japan Co., Ltd. were used, and between the concrete surface and the lightweight cellular concrete panel,
From the concrete surface side, a 10 mm thick non-woven fabric made by Teijin, "Teijin Keeper (Part No. K-1000)", titanium mesh,
NIPPON SHOKUBAI's water-absorbent polymer sheet product name "Water-absorbent polymer sheet", CRK's swelling rubber, water swelling rubber (volume expansion rate 8 times) are attached in order, and finally the non-woven fabric comes into contact with the concrete surface with a lightweight cellular concrete panel. And the electrolyte solution was supplied between the concrete surface and the concrete panel. Example 1 was repeated except that a direct current having a current density of 1 A / m ² was applied.

As a result, the content of salt in the concrete was reduced to 10% or less before the treatment, and it was confirmed that the concrete was subjected to the reforming treatment. Further, since the plate-shaped molded product was used as the electrolyte holding material, no accident such as contamination of the surrounding environment or injury of workers occurred.

Comparative Example About 30 years after construction, a test was conducted using a part of a reinforced concrete wall having a height of 4 m, a width of 10 m, and a thickness of 35 cm, which contained a considerable amount of salt. Example 1 except that a wire mesh having a diameter of 6 mm and an interval of 10 cm was fixed to the concrete surface with a plastic anchor, and the alkaline aqueous solution and the cellulose fiber were sprayed on the wire mesh to form external electrodes.
I went the same way.

As a result, the amount of salt content in the concrete was greatly reduced as in Example 1, but the spraying work of the cellulose fiber and the alkaline solution caused a great scattering to the surrounding environment, and the cleaning work after the work was completed. Is difficult,
Significant effort was required as compared with the examples.

[0037]

EFFECTS OF THE INVENTION By using the method of the present invention, it is possible to sufficiently bring out the effect of modifying concrete, and to reduce the danger at the time of work and the adverse effects on the surrounding environment.
By using a plate-shaped molded product or a cloth-shaped substance as the electrolyte solution holding material, it becomes possible to attach the external electrode very easily. The plate-shaped molded product can be continuously used as a surface finishing material even after the energization treatment. By using the water-absorbing substance and / or the swelling substance, the electrolyte solution holding material can be brought into close contact with the surface of the concrete, so that the concrete modification treatment work can be made more reliable. Become. Corners, bends,
And uneven concrete can also be modified.
And other effects.

Claims (2)

(57) [Claims] 1. A steel material inside concrete is used as an internal electrode, an electrode installed at one or more places on the surface of concrete is used as an external electrode, and a plate-shaped molded product and / or an external electrode is provided around the external electrode.
Or, install an electrolyte solution holding material with a thickness of 1 to 20 cm consisting of a cloth-like substance, and pour water or electrolyte solution on the concrete surface just enough.
A method for modifying concrete, which comprises supplying and supplying an electric current between the external electrodes and / or between an external electrode and the internal electrode. 2. An electrolyte solution holding material is a water-absorbing substance and / or
The method for modifying concrete according to claim 1, further comprising a swelling substance.