Technical Field The present invention relates to a method and an apparatus for constructing reinforcements of concrete structures, which can prevent separation between concrete structures and fiber reinforced composites by removing air contained in the fiber reinforced composites and, at the same time, impregnating epoxy sufficiently, thereby increasing bonding force.

Background Art In general, concrete structures such as beams, slabs and pillars serve to bear loads such as bending, compression and buckling. Such concrete structures are repaired and reinforced because they cannot maintain their design strength due to defects such as cracks, and the reinforcing work is carried out by generally using fiber reinforced composites, such as carbon fiber or glass fiber suitable for making the concrete structures lightweight as well as reducing a construction period.

FIG. 1 illustrates a flow chart of a conventional method for reinforcing a concrete structure, and FIG. 2 illustrates an enlarged sectional view of a conventional reinforcement configuration of the concrete structure. As shown in FIGS. 1 and 2, in the conventional method for reinforcing the concrete structure, first, if there are defects, such as cracks, on reinforced surfaces 1 and 3 of the concrete structure, epoxy impregnant is inserted into the cracked parts to repair the cracked parts.

After that, if there are foreign matters, such as dust or paint, on the reinforced

surfaces 1 and 3, the foreign matters are removed and the reinforced surfaces 1 and 3 are adjusted.

Uneven parts, which may be formed on the adjusted reinforced surfaces 1 and 3, are filled up and primer 7 is coated in order to adhere fiber reinforced composites 5 on the reinforced surfaces 1 and 3 thoroughly.

Epoxy 9 is coated on the parts where the primer 7 is coated using a brush or a roller for coating, wherein the epoxy 9 serves to support compression force, as if concrete does, after being impregnated into the fiber reinforced composites 5.

The fiber reinforced composite 5 is adhered on the part where the epoxy 9 is first coated, and it can be varied according to the length of the reinforced surfaces 1 and 3, although it is adhered generally 5m in length. The fiber reinforced composite 5 serves to support tension force like reinforced rods.

Next, the epoxy 9 first coated on the fiber reinforced composite 5 is pressed by a mangle, so that epoxy 9 is impregnated and air that remained in the fiber reinforced composite is removed.

After the impregnation of the epoxy 9 and the removal of the air, epoxy 11 is second coated on the fiber reinforced composite 5 in the same manner as the first coating of epoxy.

After the second coating of the epoxy 11, it is cured and the reinforcing work using the fiber reinforced composite 5 is finished.

In the reinforcing work, one fiber reinforced composite 5 is used, and two or more of fiber reinforced composites 5 can be piled up and used if the concrete structure is severely damaged. At this time, after the second epoxy coating, a second fiber reinforced composite is adhered without curing, the second epoxy

impregnation and the air removal are performed, and then, epoxy is third coated and cured on the second fiber reinforced composite. By repetition of the above process, a reinforcing work of multi-stage structure, generally triple layer, can be performed.

Meanwhile, if the reinforce surfaces 1 and 3 are not in a straight line, for example, edge parts where the beam and the pillar meet, the reinforcing work, as shown in FIG. 1, must be performed after a veneered part 13 of epoxy injection or mortar is formed. The reason is that when the fiber reinforced composite 5 is adhered on the reinforced surface 1 of the beam and then the fiber reinforced composite 5 is adhered on the reinforced surface 3 of the pillar, it is to prevent that the fiber reinforced composite 5 adhered on the reinforced surface 1 of the beam is pushed and separated from the edge part.

Like the above, the fiber reinforced composite 5, in which epoxy 9 and 11 are impregnated, can form structures like the reinforced concrete (the reinforced rod is epoxy, and concrete is fiber reinforced composite).

However, the conventional method for reinforcing the concrete structures has the following problems.

First, because the work that the fiber reinforced composite is adhered on the reinforced surface through epoxy is carried out manually using the roller, if the compression force of the roller is not uniform, the fiber reinforced composite and the reinforced surface are not adhered closely to each other, and thereby an air layer may be formed between the fiber reinforced composite and the reinforced surface due to the remaining air. The air layer may cause separation phenomenon, thereby separating the fiber reinforced composite from the reinforced surface to lower the reinforcing effect.

Second, if two or more of the fiber reinforced composites are folded and

constructed, it is far more difficult to remove the air because weight of epoxy and fiber reinforced composite is added, and the reinforced effect drops because the remaining air layer accelerates the separation of the fiber reinforced composite adhered on the reinforced surface.

Third, when the reinforced surface has a curved part like the edge part, the veneered part causes loss of material and extension of construction period, thereby deteriorating its economical efficiency and production efficiency.

Fourth, if two or more of the fiber reinforced composites are folded and constructed, the fiber reinforced composites have to be adhered one after another, thereby lowering the construction efficiency and economical efficiency due to the increase in the number of construction processes.

Fifth, if the length of the reinforced surface (for example, more than 5m), it takes too much time in impregnating epoxy on the fiber reinforced composite and removing the air remaining in the fiber reinforced composite by the compression force of the roller, and thereby, epoxy which is not impregnated may be cured previously. Therefore, the length of the fiber reinforced composite is restricted.

Sixth, because the compression force of the roller is varied at a place where epoxy is sufficient and at a place where epoxy is not sufficient when epoxy coated on the reinforced surface is impregnated into the fiber reinforced composite, the thickness of the fiber reinforced composite is not uniform and the reinforcing effect drops due to insufficient impregnation.

Seventh, when epoxy is coated and a worker adheres the fiber reinforced composite, if noxious epoxy drops on the worker's body, it injures the worker's skin and the circumference of the construction site may be polluted, and thereby, the environment of the construction site may be poor.

Disclosure of the Invention Accordingly, an object of the present invention is to provide a method and an apparatus for constructing a reinforcement of concrete structures, which can completely remove the air remaining in reinforced surfaces and fiber reinforced composites to adhere the reinforced surface and the fiber reinforced composite closely to each other.

Another object of the present invention is to provide a method and an apparatus for constructing a reinforcement of concrete structures, which can perform a reinforcing construction at once without regard to the form of the reinforced surfaces or the length of the reinforced surface.

To achieve the above objects, the present invention provides a method for reinforcing concrete structures, the method including the steps of providing reinforced surfaces of the concrete structure; coating primer on the reinforced surfaces; mounting fiber reinforced composites on the coated reinforced surfaces in one or more folds; mounting a supply path at a side of the fiber reinforced composite and mounting a discharge path at the other side of the fiber reinforced composite to supply epoxy to the fiber reinforced composite; putting a cover on the supply path, the fiber reinforced composite and the discharge path and sealing a space between the reinforced surfaces and the cover; discharging the air formed between the reinforced surfaces and the cover through the discharge path by a pumping action and forming a vacuum condition; impregnating epoxy into the fiber reinforced composite by pressure difference when the vacuum condition is made between the reinforced surfaces and the cover; and performing a finishing work after impregnating epoxy into the fiber reinforced composite.

Through the above method, the air formed in the reinforced surface and the

fiber reinforced composite can be removed completely to adhere them closely to each other.

In another aspect, the present invention provides an apparatus for reinforcing concrete structures, the apparatus including: fiber reinforced composites of one or more folds mounted on reinforced surfaces of the concrete structure coated with primer; a supply path mounted at a side of the fiber reinforced composite to supply epoxy to the fiber reinforced composite ; a discharge path mounted at the other side of the fiber reinforced composite; a cover covering the supply path, the fiber reinforced composite and the discharge path and sealing them; and a vacuum pump mounted at the discharge path for forming a vacuum condition between the reinforced surfaces and the cover, the vacuum pump allowing epoxy to be impregnated into the fiber reinforced composite by pressure difference.

Through the above apparatus, the reinforcement construction can be performed at once without regard to the form of the reinforced surface and the length of the reinforced surface.

It is preferable that a guide member is installed between the supply path and the fiber reinforced composite to make epoxy be impregnated into the fiber reinforced composite more smooth.

Brief Description of the Drawings Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawing in which: FIG. 1 illustrates a flow chart of a conventional method for reinforcing a concrete structure;

FIG. 2 illustrates an enlarged sectional view of a conventional reinforcement configuration of the concrete structure; FIG. 3 illustrates a flow chart of a method for reinforcing concrete structures according to a preferred embodiment of the present invention; FIG. 4 illustrates a sectional view showing that a reinforcing device of the concrete structure is installed on a reinforced surface, according to the embodiment of the present invention ; FIG. 5 illustrates a plan view of FIG. 4; FIG. 6 illustrates an enlarged sectional view showing reinforcement construction is performed according to the embodiment of the present invention; FIG. 7 illustrates a flow chart of a method for reinforcing concrete structures according to another preferred embodiment of the present invention; FIG. 8 illustrates a sectional view showing that a reinforcing device of the concrete structure is installed on a reinforced surface, according to the second embodiment of the present invention; and FIG. 9 illustrates an enlarged sectional view showing reinforcement construction is performed according to the second embodiment of the present invention.

Preferred Embodiment of the Invention The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. For reference, like reference characters designate corresponding parts throughout several views.

<Embodiment 1> FIG. 3 illustrates a flow chart of a method for reinforcing concrete structures according to a preferred embodiment of the present invention. FIG. 4 illustrates a sectional view showing that a reinforcing device of the concrete structure is installed on a reinforced surface, according to the embodiment of the present invention. FIG.

5 illustrates a plan view of FIG. 4, and FIG. 6 illustrates an enlarged sectional view showing reinforcement construction is performed according to the embodiment of the present invention. As shown in FIGS. 3 through 6, in the method for reinforcing the concrete structure according to the present invention, first, like the conventional reinforcing method, cracks of reinforced surfaces 1 and 3 are repaired and adjusted, and primer 7 is coated on the reinforced surfaces 1 and 3. The coated primer 7 penetrates the adjusted surface to reinforce the reinforced surfaces 1 and 3 and to raise adhesion force between the reinforced surfaces 1 and 3 and epoxy 11.

Next, fiber reinforced composite 5 is mounted on the reinforced surfaces 1 and 3 on which primer 7 is coated. The area of the fiber reinforced composite 5 is equal to or larger than that of the reinforced surfaces 1 and 3, and one or more of the reinforced surfaces 1 and 3 can be folded and constructed according to the extent of damage of the reinforced surfaces 1 and 3.

A supply path 20 is mounted at a side of the fiber reinforced composites 5 mounted on the reinforced surfaces 1 and 3, and a discharge path 30 is mounted at the other side of the fiber reinforced composites 5. Preferably, the supply path 20 and the discharge length 30 have the same length as the fiber reinforced composites 5.

Especially, in case of the reinforced surface 3 of a pillar, it is preferable that the supply path 20 is mounted at a lower portion of the reinforced surface 3 and the discharge path 30 is mounted at an upper portion of the reinforced surface 3. The

reason is to prevent impregnated epoxy 40, which will be described later, from being concentrated downward by gravity.

An inlet 22 of the supply path 20 is connected to a container (not shown) containing epoxy through a hose 24. Therefore, epoxy 40 is led to the supply path 20 by difference of pressure, and then impregnated on upper and lower surfaces of the fiber reinforced composite 5 uniformly along a width direction of the fiber reinforced composite 5. Meanwhile, an outlet 32 of the discharge path 30 is connected to a vacuum pump 50 through a hose 34 to discharge the air between the reinforced surfaces 1 and 3 and a cover 60, which will be described later, and to discharge epoxy 40 remaining after being impregnated into the fiber reinforced composite 5. Preferably, the inlet 22 of the supply path 20 and the outlet 32 of the discharge path 30 are disposed diagonally to each other to make compression of the cover 60 and movement of epoxy 40 smooth. Furthermore, it is also possible to connect each epoxy container to both ends of the supply path 20 or connect each vacuum pump 50 to both ends of the discharge path 30.

The cover is put on the supply path 20, the fiber reinforced composite 5 and the discharge path 30, which are mounted on the reinforced surfaces 1 and 3, and seals them. Therefore, a space between the reinforced surfaces 1 and 3 and the cover 60 is sealed excepting the inlet 22 of the supply path 20 and the outlet 32 of the discharge path 30. It is preferable that the inside of the cover 60 is sealed using an adhesive tape 70, which can fix it on the reinforced surfaces 1 and 3 while being isolated from the outside of the cover 60.

Next, if the vacuum pump 50 is operated to form a vacuum (including a state near to vacuum condition) between the reinforced surfaces 1 and 3 and the cover 60, the cover 60 is contracted to the utmost by suction force and the fiber reinforced

composite 5 is compressed, and thereby not only the air formed in the fiber reinforced composite 5 but also the air contained in the cover 60 are completely removed through the discharge path 30.

If the vacuum condition is formed between the reinforced surface 1 and 3 and the cover 60, epoxy 40 is injected into the inside of the cover 60 by pressure difference with the hose 24 put into the epoxy container. Epoxy 40 is moved to the supply path 20, and then, started to be impregnated into the upper and lower surfaces of the fiber reinforced composite 5 through the supply path 20 at the same time. By a repeated pumping action of the vacuum pump 50, epoxy 40 is impregnated into the whole fiber reinforced composite 5, and remaining epoxy 40 after the impregnation is discharged to the outside through the discharge path 30.

Finally, after the impregnation of epoxy 40 into the fiber reinforced composite 5, a finish work is performed. When epoxy 40 is completely impregnated into the fiber reinforced composite 5, each hose 24 and 34 is curved and stops the inlet 22 of the supply path 20 and the outlet 32 of the discharge path 30.

Moreover, it will be appreciated that a removable valve may be mounted at the inlet 22 of the supply path 20 and the outlet 32 of the discharge path 30. After that, when epoxy 40 is impregnated into the fiber reinforced composite 5 sufficiently, epoxy 40 is cured. After the curing of the epoxy, the cover 60, the supply path 20 and the discharge path 30 are removed.

Meanwhile, to prevent a slow supply of epoxy 40 into the fiber reinforced composite 5 due to the close adhesion between the supply path 20 and the cover 60, it is preferable to install a guide member 80 between the supply path 20 and the fiber reinforced composite 5 after the adhesion of the fiber reinforced composite 5. Also the guide member 80 is removed after the construction work.

Furthermore, if the fiber reinforced composite 5 and the reinforced surfaces 1 and 3 are adhered far closer than the fiber reinforced composite 5 and the cover 60, epoxy 40 may be impregnated slowly between the fiber reinforced composite 5 and the reinforced surfaces 1 and 3. To prevent the above, a net type screen 85 may be mounted before the adhesion of the fiber reinforced composite 5. As described above, the guide member 80 and the screen 85 allow epoxy 40 to be impregnated into the fiber reinforced composite 5 smooth.

Additionally, to improve sealing efficiency of the cover 60, a packing 90 may be mounted on an outer circumference of the inlet 22 of the supply path 20 and on an outer circumference of the outlet 32 of the discharge path 30.

Hereinafter, an apparatus for reinforcing the concrete structure using the fiber reinforced composite according to the preferred embodiment of the present invention.

The apparatus for reinforcing the concrete structure according to the present invention includes one or more folds of fiber reinforced composites 5, which are installed on reinforced surfaces 1 and 3, a supply path 20, a discharge path 30, a cover 60 for sealing the reinforced surfaces 1 and 3, and a vacuum pump 50 mounted on the discharge path 30.

For the fiber reinforced composite 5, carbon fiber, glass fiber, aramid fiber, etc. may be used. Moreover, it is preferable that a screen 85 is mounted between the reinforced surfaces 1 and 3 and the fiber reinforced composite 5 to impregnate epoxy 40 smooth. For the screen 85, it is preferable to use a polyethylene net, a woven net, and so on.

It is preferable that the supply path 20 is a spring in the form of a coil having a predetermined pitch (e. g., 1 to 5mm) and mounted at a side of the fiber reinforced

composite 5 to lead epoxy 40 and supply epoxy 40 into the fiber reinforced composite 5 uniformly. The spring has enough strength to prevent contract and transformation due to vacuum pressure. It is appreciated that instead of the spring, a pipe having a plurality of holes to discharge epoxy 40 may be mounted. The inlet 22 formed at an end of the supply path 20 protrudes to the outside of the cover 60.

Meanwhile, a guide member 80 may be mounted between the supply path 20 and the fiber reinforced composite 5 to impregnate epoxy 40 to upper and lower portions of the fiber reinforced composite 5 smooth. The guide member 80 has to have a path to move epoxy 40 in the inside of the guide member 80, for example, nonwoven fabric.

The discharge path 30, like the supply path 20, is a spring or a pipe having a plurality of holes to discharge air or epoxy 40, and mounted at the other side of the fiber reinforced composite 5.

The cover 60 covers the supply path 20, the fiber reinforced composite 5 and the discharge path 30 and seals the inside thereof. It is preferable that the inside of the cover 60 is sealed by adhering an adhesive tape 70 on a border of the cover 60.

For the cover 60, it is preferable to use transparent polyethylene film, which can be separated from epoxy 40 well and allow a worker to observe the impregnation of epoxy 40 from the outside. Furthermore, to improve the sealing efficiency of the cover 60, it is preferable to mount a packing 90 on an outer circumference of the inlet 22 of the supply path 20 and an outer circumference of the outlet 32 of the discharge path 30, which are in contact with the cover 60.

The vacuum pump 50 is to completely remove the air formed between the reinforced surfaces 1 and 3 and the cover 60, and vacuum pressure is 3 to 6kg/cm2 per lm2.

<Embodiment 2> In a second preferred embodiment according to the present invention, without using the screen 85 of the first embodiment, which is mounted between the reinforced surfaces 1 and 3 and the fiber reinforced composite 5, hatching 6 is formed on the reinforced surfaces 1'and 3'to achieve a complete adhesion between the reinforced surfaces and the fiber reinforced composites. It is shown in FIGS. 7 to 9.

The second embodiment is similar to the first embodiment, but different from the first embodiment in respect that the hatching 6 is formed with a grinder or a cutter before primer is coated on the reinforced surfaces. Therefore, because primer 7 is coated on the reinforced surfaces 1'and 3j'on which the hatching 6 is formed, penetration of primer 7 is better and the reinforced surfaces 1'and 3'can be reinforced better. Additionally, the hatching 6 serves as a guide path of epoxy 9, thereby improving adhesion efficiency between the reinforced surfaces 1'and 3'and the fiber reinforced composite 5, and serves as a guide path of air, thereby removing the air efficiently. Therefore, the second embodiment according to the present invention does not need the screen 85, thereby simplifying the construction process and apparatus configuration.

Industrial Applicability As described above, the method and apparatus for constructing a reinforcement of concrete structures according to the present invention have the following advantages.

First, because the air formed in the inside of the cover sealing the supply path, the fiber reinforced composite and the discharge path is removed completely by

the pumping action of the vacuum pump and the inside of the cover is maintained in a vacuum condition, the complete adhesion between the reinforced surfaces and the fiber reinforced composites increases the reinforcing effect.

Second, epoxy filling the supply path by the pressure difference flows into the fiber reinforced composite and is impregnated into the fiber reinforced composite uniformly, thereby improving the reinforcing effect.

Third, because epoxy is impregnated in the state that the cover compresses the fiber reinforced composite uniformly by the vacuum condition, the thickness of the fiber reinforced composite is uniform.

Fourth, the guide member mounted between the supply path and the fiber reinforced composite make the impregnation of epoxy into the fiber reinforced composite smooth.

Fifth, the hatching formed on the reinforced surfaces increases the penetration effect of primer, thereby reinforcing the reinforced surfaces better.

Moreover, the hatching serving as a guide path of epoxy and air allows epoxy to be impregnated sufficiently between the reinforced surfaces and the fiber reinforced composites and leads discharge of the air, and thereby the reinforced surfaces and the fiber reinforced composites can be adhered completely.

Sixth, the screen mounted between the reinforced surfaces and the fiber reinforced composites forms clearance, thereby making the impregnation of epoxy smooth.

Seventh, because the air can be removed by the vacuum pump and epoxy can be impregnated by the pressure difference even though the fiber reinforced composites are constructed in two or more folds, the reinforcement can be finished through once process, and thereby the reinforcing effect and construction efficiency

are improved to raise economical efficiency and production efficiency.

Eighth, if the reinforced surfaces are not in straight line (e. g., a stepped structure), because the cover adheres the fiber reinforced composite completely, additional veneered part is not needed.

Ninth, because the reinforced composite can be constructed at once without cutting the reinforced composite even though the reinforced surfaces are long, the construction efficiency and the reinforcing effect are improved.

Tenth, because being impregnated and cured in the inside of the sealed cover, epoxy does not pollute the circumference of the construction site and is not stained on the worker's body.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.