JP2002242445A - Repairing method of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repairing method of a concrete structure having a reinforcing effect over a long period while being lightweight and easily executable. SOLUTION: This repairing method of the concrete structure is characterized by smoothing and hardening a surface after embedding a sheet-like fiber reinforcing member composed of alkali-proof glass fiber including ZrO2 by 14 mass % or more by applying cement mortar composed of cement, a thin aggregate, water, and aqueous dispersion to the concrete structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a method for repairing a concrete structure, and more particularly to a method for repairing a concrete structure using a sheet-like fiber reinforced cement mortar made of alkali-resistant glass fiber.

[0002]

2. Description of the Related Art In a concrete structure, when metal such as a reinforcing bar embedded therein becomes rusted due to neutralization of concrete or intrusion of water from fine cracks, cracks occur due to volume expansion. It is well known to destroy or destroy. When the chloride ion concentration in the concrete is high, the progress proceeds rapidly.

[0003] The repair is generally performed in the order of groundwork adjustment, crack repair and cross-section repair, and fall prevention measures. The ground preparation includes a hanging processing and a ground processing step. Concrete is lifted at a location where floating or peeling of the concrete structure is confirmed by inspection. Thereafter, in order to secure adhesion to the peeling-preventing material, a base treatment by sand blast, water jet, or the like is performed. After the base adjustment is completed, crack repair and cross-section repair using an epoxy resin-based or inorganic injection material are performed, if necessary, and finally, fall prevention measures are taken.

[0004] There are methods for preventing peeling, such as installing a steel plate or attaching fiber reinforced plastic (FRP), but each has a problem.

[0005] In the steel sheet installation method, heavy equipment is used for construction due to the weight of the steel sheet as a reinforcing material, which requires a large amount of work, and is limited in a limited space such as the inside of a building, an underground structure, or a tunnel. In addition to construction problems, such as the fact that construction may be extremely difficult and the difficulty of working on complex structures due to poor workability of steel plates, concrete structures that are subject to repair There is a problem that the foundation work of the object itself may be required.

In the reinforcing method using FRP, since a FRP reinforcing body impregnated with a thermosetting resin is bonded to a surface of a concrete structure where a tensile force acts, a tensile force acts on the structure. When distortion occurs in the bonded portion, shear fracture easily occurs, and the original high strength of FRP cannot be utilized for reinforcement. Various methods have been proposed to prevent this shear failure, but are not yet sufficient.
Further, glass fibers for plastic reinforcement, which are most frequently used as reinforcing fibers for FRP and are inexpensive, do not have alkali resistance, and question the durability of FRP used in contact with concrete. There is also a side to do. Furthermore, since the FRP reinforcement is a combustible material, when the concrete structure has a fireproof structure or a fireproof structure, there is a problem that the reinforcement does not provide a fireproof or fireproof structure.

[0007]

When a concrete structure is repaired and peeling is prevented, in addition to reinforcement against bending and shearing, a force acts on the concrete structure to prevent large deformation after reaching the maximum strength. In order to prevent this, it is necessary to impart high toughness. It is an object of the present invention to provide a method for repairing a concrete structure that is lightweight, can be easily constructed, and has a long-term reinforcing effect.

[0008]

SUMMARY OF THE INVENTION The present inventor has set forth the above problems.
As a result of repeating various experiments to solve
Applying cement mortar-based peeling-preventive material
And ZrO in it _Two14% by mass or more
Sheet-like fiber reinforcement made of alkali-resistant glass fiber
By embedding, it is lightweight, easy to construct,
Repair method for concrete structures
I found it.

That is, in the method for repairing a concrete structure according to the present invention, a cement mortar made of cement, fine aggregate, water, an aqueous polymer dispersion or the like is applied to the concrete structure, and contains at least 14% by mass of ZrO _2. After embedding the sheet-like fiber reinforcement made of alkali-resistant glass fibers, the surface is smoothed and cured.

[0010]

In the present invention, a concrete structure refers to a structure constructed of a cement-based material such as concrete, cement mortar, polymer cement mortar, and more specifically, a bridge, a floor slab, a high-rise to low-rise general building. Pillar of thing
Beams and walls, underground structures, tunnel inner surfaces, etc.

The peeling-preventing material referred to in the present invention is based on cement, and is generally used as a material for building civil engineering, such as cement, fine aggregate, water, aqueous polymer dispersion, etc. Cement mortar. If necessary, the cement-based anti-fouling agent may contain a water-reducing agent, a superplasticizer, a thickener, a waterproofing agent, a rust inhibitor, a hardening accelerator, a hardening retarder, and other admixtures. Good.

As the admixture used in the present invention, any admixture can be used as long as it is a material for building civil engineering and is usually added to cement mortar according to the purpose.

The polymer cement mortar of the present invention is:
An aqueous polymer dispersion is added to a cement mortar made of cement, fine aggregate, water, an admixture, etc. for the purpose of improving fluidity and adhesion, reducing water absorption, and the like. Examples of the polymer constituting the aqueous polymer dispersion include acryl, ethylene vinyl acetate, styrene butadiene, urethane and the like, and a mixture thereof.

Since the glass fiber of the present invention contains ZrO ₂ in an amount of 14% by mass or more, it has excellent alkali resistance. Even when this is used as a reinforcing material for a cement-based material, the glass fiber is formed by an alkaline substance in the cement. Not easily eroded. Therefore, the tensile strength of the glass fiber can be prevented from being reduced by the alkaline substance, and the reinforcing effect can be maintained even when used as a reinforcing material for a cement-based material.
Using glass fiber for plastic and glass fiber for acid resistance,
A sheet-like fiber reinforcing material provided with an alkali-resistant coating is not preferable because its durability against alkali is not sufficient.

The specific composition of the glass fiber having excellent alkali resistance that can be used in the present invention is SiO _{2 in} mass%.
54-65%, ZrO ₂ 14-25%, Li ₂ O 0
_{~5%, Na 2 O 10~17%} , K 2 O 0~8%, R
(Wherein, R represents, Mg, Ca, represents Sr, Ba, and _{Zn) 0~10%, TiO 2 0~7} %, Al 2 O 3 0
２2%, more preferably, by mass%, SiO _{2
57~64%, ZrO 2 18~24%,} Li 2 O 0.5
_{~3%, Na 2 O 11~15%} , K 2 O 1~5%, R
(Wherein, R represents Mg, Ca, Sr, Ba, and _{Zn) 0.2~8%, TiO 2 0.5~5} %, Al 2 O 3
0 to 1%.

The sheet-like fiber reinforcing material used in the present invention includes a net, a continuous strand mat, a chopped strand mat and the like. The aperture is 5 mm or more. Among the cement mortar materials used as the peeling preventive material, the largest one is fine aggregate, and if the mesh size is 5 mm or more, which is the maximum particle size, embedding the sheet-like fiber reinforcing material in the cement mortar. Becomes easier. Further, it is not preferable to embed a sheet-like fiber reinforcing material having an opening of 5 mm or less, since cement mortar on the surface side of the sheet-like fiber reinforcing material may peel off.

When the net is used, it can be used regardless of the weave method, such as braided fabric or entangled weave. In addition, if the water-based polymer dispersion is applied to the net, etc., it is easy to handle without misalignment, and by selecting a water-soluble polymer dispersion with good water compatibility, the familiarity with the mortar can be improved. Better and better. Also, when a mat is used, it is preferable to use the aqueous polymer dispersion as the primary binder because the affinity with the mortar is improved.

If the mass per unit mass (basis weight) of the sheet-like fiber reinforcing material is too small, a sufficient reinforcing effect cannot be obtained, so that it is preferably 50 g / m ² or more.

The application of the cement mortar to the concrete structure may be performed by any ordinary application method such as spraying or ironing. Further, it is preferable that the applied thickness of the cement mortar is constant and is such that the sheet-like fiber reinforcing material can be sufficiently buried.

After the cement mortar is applied to the surface of the concrete structure as a peeling preventive material, the sheet fiber reinforcing material is embedded in the peeling preventing material. In this case, in order to maximize the reinforcing effect of the sheet fiber reinforcing material, It is preferable to embed the sheet-like fiber reinforcement so as not to be loosened. For example, two opposite sides or four corners of the sheet-like fiber reinforcement may be pressed against the peel-prevention material while pulling each other so that the sheet-like fiber reinforcement does not loosen. Further, the sheet-like fiber reinforcing material may be embedded with a grooved roller or a pressing jig wider than the width of the sheet-like fiber reinforcing material.

In the case of construction on a very large flat surface, a spliced portion of the sheet-like fiber reinforcement is generated. However, in order to maintain the continuity of the sheet-like fiber reinforcement, the overlap portion is 5 cm.
It is desirable to secure the above.

Next, the surface of the peeling-preventing material, such as a flattening with a trowel, is smoothed to obtain a smooth surface, which is then cured. Further, after the sheet-like fiber reinforcing material is embedded in the peel-off preventing material, the sheet-like fiber reinforcing material may be further applied to have a predetermined thickness.

If necessary, an appropriate pattern or the like may be formed on the surface of the anti-falling material before curing, or finishing such as painting may be performed after curing.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for repairing a concrete structure according to the present invention will be described in detail based on an embodiment using a net as a sheet-like fiber reinforcing material. Table 1 shows Examples of the present invention, and Table 2 shows Comparative Examples.

[0025]

[Table 1]

[0026]

[Table 2]

The alkali-resistant glass fiber net was prepared as follows.

First, a continuous fiber for forming a net
(Roving), the strand count is 155,6
20,1100,2500 tex alkali-resistant glass fibers (SiO ₂ 61.0% by mass, ZrO ₂
5 wt%, Li ₂ O 1.5 wt%, Na ₂ O 12.3
% By mass, 2.6% by mass of K ₂ O, 0.5% by mass of CaO, and 2.6% by mass of TiO ₂ ).

Next, using the rovings, nets were prepared by the weaving methods shown in Tables 1 and 2 so as to have a predetermined mesh interval and a basis weight. The basis weight was adjusted by setting the eye interval in advance and combining rovings with different numbers. 1 net solid woven
An aqueous polymer dispersion of 0 to 30% by mass was applied, and a sealing treatment was performed (hereinafter referred to as an AR glass net).

For comparison, a net coated with plastic reinforcing glass fiber (hereinafter referred to as E glass net) and a net coated with acid-resistant glass fiber (hereinafter referred to as C), both of which do not contain any ZrO _2.
Glass net).

As the concrete structure to be reinforced, cement, fine aggregate having a maximum particle size of 5.0 mm, and a maximum particle size of 25 m
m coarse aggregate and an admixture (manufactured by NMB Co., Ltd., trade name: Reobuild SP-8N), and cement 269 kg /
m ³ , fine aggregate 820 kg / m ³ , coarse aggregate 1023 kg / m
^3, water 172kg / m ^3, consists of admixture 3 kg / m ³ 1
A 5 cm × 15 cm × 53 cm hardened concrete body (hereinafter referred to as a “reinforced body”) was prepared.

The body to be reinforced after curing for two weeks at 20 ° C. and 60% RH was reinforced with a peel prevention material and a net. A cement mortar was prepared in which a river sand / cement ratio was 3 and an acrylic emulsion was added to the cement at a solid content of 5% by mass based on the solid content. 53 × 15 of reinforced body
The surface of one cm was subjected to a base treatment with a sander, and the prepared anti-stripping material was applied so as to have a thickness of 2 cm. Further, the nets shown in Tables 1 and 2 were embedded at a position 2 mm from the surface, and the surface was smoothed using an iron,
Cured at 60 ° C. and 60% RH for 2 weeks (hereinafter referred to as test specimen).
Half of the test pieces prepared were immersed in 70 ° C. warm water for 10 days. 1 day immersion in 70 ° C warm water is about 1 outdoor exposure
10 years of immersion corresponds to about 10 years of outdoor exposure.

The reinforced body and the test body before and after immersion in hot water were subjected to a trisection bending test with a bending span of 450 mm. The loading acceleration was 2 mm / min, and the number of test pieces was n =
3 was performed.

Tables 1 and 2 show the type of glass used in the net, the weaving method, the basis weight, the spacing between the nets, the working time required for embedding the net, the bending strength in the bending test, the absorbed energy ratio, and the breaking properties. . The absorbed energy ratio is the ratio of the absorbed energy up to the end of the test when the reinforced body (Comparative Example 5) is set to 1, and the destruction property is defined as “A” when the destruction of the peeling prevention material is defined as “A”. Peeling of the peeling preventive material was evaluated as "B".

In Examples 1 to 4 shown in Table 2 of the present invention, since the eye interval was 5 mm or more, the net embedding was completed in about 30 seconds, and compared with Comparative Example 2 shown in Table 2. It can be seen that the net can be easily embedded.

In Comparative Example 1, the net basis weight was 50 g.
/ M ² or less, a sufficient reinforcing effect is not seen, but in Examples 1 to 4, a sufficient effect is seen because the basis weight is 50 g / m ² or more. In particular, a great effect is seen on the absorbed energy.

Comparative Examples 3 and 4 have good workability and are heated at 70 ° C.
AR glass nets with almost the same basis weight before immersion
Almost the same value as in Example 2 used was obtained.
Hot water immersion 10 for accelerated curing equivalent to about 10 years of external exposure
The bending properties after days are inferior to those of Example 2, especially
There is a sharp drop in the energy yield, and ZrO _Two
AR glass net with 14% by mass or more added
By using it, it is possible to obtain a durable peeling prevention layer
You can see what you can do.

[0038]

As described above, according to the present invention, when repairing a concrete structure, it is lightweight, can be easily constructed, bends and reinforces, and at the same time, large toughness can be imparted. Can be maintained.

Claims (3)

[Claims] 1. A sheet fiber made of an alkali-resistant glass fiber containing 14% by mass or more of ZrO ₂ by applying a cement mortar made of cement, fine aggregate, water, an aqueous polymer dispersion or the like to a concrete structure. A method for repairing a concrete structure, characterized by smoothing and hardening the surface after embedding a reinforcing material. 2. The method for repairing a concrete structure according to claim 1, wherein the aperture of the sheet-like fiber reinforcement made of alkali-resistant glass fiber is 5 mm or more. 3. The method for repairing a concrete structure according to claim 1, wherein the basis weight of the sheet-like fiber reinforcement made of alkali-resistant glass fiber is 50 g / m ² or more.