JP2009114815A - Reinforcing structure of hollow concrete structure, and reinforcing method of hollow concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing structure of a hollow concrete structure capable of increasing the proof stress of an object to be reinforced at low cost by filling a hollow part with a lightweight filling body of high strength, and moreover giving cut-off performance. <P>SOLUTION: A large number of small spheres 23 formed of a foam resin material are filled in a hollow part 19 formed in the concrete structure W and having an opening 21, and clearances between the small spheres 23 are filled with a resin body 27 of multi-blowhole shape formed by curing filled resin. The filled resin may be fiber-reinforced resin including long fibers. It is preferable to attach cloth to the inner surface of the hollow part 19. In the reinforcing method of the hollow concrete structure, the concrete structure W is installed in a direction to place the opening 21 on the topside, and a resin filling pipe is inserted from the opening 21 to the bottom part of the hollow part 19. After filling the small spheres 23 in the hollow part 19, the opening 21 is temporarily covered with a cover body formed with air holes. The resin filling pipe is pulled out while injecting uncured liquid resin from the resin filling pipe, and the injected resin is cured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reinforcing structure for a hollow concrete structure and a reinforcing method for the hollow concrete structure.

  As a concrete structure having a hollow portion, there is a concrete electric pole, for example. The concrete electric pole is formed so that its periphery is surrounded by an outer peripheral portion made of reinforcing steel and concrete and the inside is a hollow portion. A lid is attached to the uppermost end portion of the concrete utility pole, preventing intrusion of rain and the like into the hollow portion. However, if it is subjected to weathering such as acid rain or underground leaching water or exposure to direct sunlight for a long period of time, or bending stress due to overhead wire tension, creep phenomenon or stress Cracks occur due to fatigue, and rainwater enters and causes the steel bars to corrode and expand. For this reason, in the concrete electric pole in which the inside was formed in the cavity, it was conventionally performed to reinforce according to deterioration due to secular change or the like.

For example, in the method for reinforcing a concrete electric pole disclosed in Patent Document 1, a plurality of rod-shaped lower reinforcing members are inserted from an upper opening of a concrete electric pole into a hollow portion so that the lower end reaches the bottom. The plurality of inserted lower reinforcement members are evenly arranged in the hollow portion, non-shrink mortar is filled into the hollow portion to fill the gaps between the plurality of lower reinforcement members, and the upper reinforcement member is hollowed from the opening. Insert into the hollow part until the lower end reaches the vicinity of the upper end of the lower reinforcing material, and insert the non-shrink mortar into the hollow part where the upper reinforcing material is inserted, thereby closing the opening at the top of the concrete utility pole. The hollow portion is filled with non-shrink mortar.
JP 2005-307479 A

  However, if the hollow portion is filled with non-shrink mortar having a large specific gravity in the hollow portion, the weight of the object to be reinforced increases, and there is a possibility that bending may occur due to bending stress due to the increase in its own weight. Further, it is conceivable that the resin is poured and strengthened. However, if the resin has strength, the weight increases in the same manner as the mortar, there is a risk of bending due to an increase in its own weight, and the material cost becomes high. On the other hand, if a plurality of bar-shaped reinforcing members are inserted as in the prior art described above, the breakage can be avoided, but the weight of the new concrete power pole is greatly increased. There was a problem that required labor. Furthermore, a filling material such as mortar has a drawback in that it cannot obtain water-stopping properties and has limited applications.

  The present invention has been made in view of the above circumstances, and is a hollow concrete structure that can fill a hollow portion with a lightweight and high-strength filler, can increase the proof stress of the object to be reinforced at a low cost, and can also provide water-stopping properties. It is another object of the present invention to provide a reinforcing structure and a method for reinforcing a hollow concrete structure.

Next, means for solving the above problems will be described with reference to the drawings corresponding to the embodiments.
The hollow concrete structure reinforcing structure according to claim 1 of the present invention is filled with a large number of small spheres 23 made of a foamed resin material in the hollow portion 19 having the opening 21 formed in the concrete structure W,
The gap S between the small spheres 23 is filled with an integral resin body 27 obtained by curing the filling resin 25.

  In this reinforcing structure of a hollow concrete structure, the hollow portion 19 is replaced with a multi-nest-like resin body 27 in which a large number of small spheres 23 are integrally embedded, and the small spheres 23 made of a foamed resin material are embedded. Accordingly, the amount of the filling resin material is reduced, and the total weight of the object to be reinforced is reduced. In addition, the hollow portion 19 is filled with an integral multi-nest resin body 27 that surrounds the small spheres 23 and has independent nests, and water-stopping occurs.

  The hollow concrete structure reinforcing structure according to claim 2 is characterized in that the small spheres are formed to have substantially the same diameter.

  In this reinforcing structure of the hollow concrete structure, by making the size of the small spheres 23 substantially uniform, the small spheres 23 are regularly arranged in the space, regularity appears in the formed gap, and the gap is filled. The multiple nest-like resin body 27 to be cured forms a substantially regular three-dimensional structure.

  The reinforcing structure for a hollow concrete structure according to claim 3 is characterized in that the filling resin 25 is a fiber reinforced resin containing long fibers.

  In the reinforcing structure of this hollow concrete structure, the filling resin 25 becomes a fiber reinforced resin mixed with long fibers such as carbon fibers, and the strength after curing increases.

  The reinforcing structure for a hollow concrete structure according to claim 4 is characterized in that a fabric is adhered to the inner surface of the hollow portion 19.

  In this reinforcing structure of the hollow concrete structure, the filling resin 25 soaks into the fabric and hardens, and the adhesion strength between the multi-nest resin body 27 and the object to be reinforced increases.

In the method for reinforcing a hollow concrete structure according to claim 5, a large number of small spheres 23 are filled in the hollow part 19 having the opening 21 formed in the concrete structure W.
A method of reinforcing a hollow concrete structure in which the gap S between the small spheres 23 is filled with an integral resin body 27 obtained by curing a filling resin 25,
The concrete structure W is installed with the opening 21 facing upward,
Insert the resin-filled tube 31 from the opening 21 to the bottom of the hollow portion 19,
After filling the hollow portion 19 from the opening 21 with the small sphere 23, the opening 21 is temporarily covered with a lid 35 having a plurality of vent holes 33 smaller than the small sphere 23,
Pulling out the resin-filled tube 31 from the hollow portion 19 while injecting an uncured liquid resin from the resin-filled tube 31,
The injection resin is cured.

  In this method of reinforcing a hollow concrete structure, the filling resin 25 enters the gap S between the small spheres 23, and the hollow portion 19 is formed by the multifocal resin body 27 in which the small spheres 23 are embedded in the filling resin 25 and cured integrally. Is buried.

In the method for reinforcing a hollow concrete structure according to claim 5, a large number of small spheres 23 are filled in the hollow part 19 having the opening 21 formed in the concrete structure W.
A method of reinforcing a hollow concrete structure in which the gap S between the small spheres 23 is filled with an integral resin body 27 obtained by curing a filling resin 25,
The concrete structure W is installed with the opening 21 facing upward,
Insert the resin-filled pipe 31 from the opening 21 to the bottom of the hollow part 19,
After filling the hollow portion 19 from the opening 21 with the small sphere 23, the opening 21 is temporarily covered with a lid 35 having a plurality of vent holes 33 smaller than the small sphere 23,
Injecting uncured liquid resin from the resin-filled tube 31, filling the hollow-filled portion 19 with the resin-filled tube 31 to leave it,
The injection resin is cured.

  In this method of reinforcing a hollow concrete structure, the filling resin 25 enters the gap S between the small spheres 23, and the hollow portion 19 is formed by the multifocal resin body 27 in which the small spheres 23 are embedded in the filling resin 25 and cured integrally. Is buried. Also, by filling up the resin-filled tube 31 in the hollow portion 19 that is used when the filled resin 25 is injected, the complexity of separately storing the resin-filled tube 31 is reduced, and workability and the like are improved.

  According to the reinforcing structure for a hollow concrete structure according to claim 1 of the present invention, a large number of small spheres made of a foamed resin material are filled in a hollow portion having an opening formed in the concrete structure. Since the gaps between the spheres were filled with a multi-nest resin body in which the filled resin was cured, the hollow part was replaced with an integrated resin body in which a large number of small spheres were embedded, and the structure was reinforced. The object is resistant to deformation such as compression, bending, bending, and buckling. And the amount of the filling resin material can be reduced by the amount of embedding the foamed resin material. Conventionally, the object to be reinforced, which has become heavy by filling the hollow part with concrete, mortar, or resin, is significantly lightened. No deformation or bending stress is generated, and the yield strength can be increased at a low cost. Further, since the total weight of the object to be reinforced becomes light, handling such as transportation becomes easy. Furthermore, since the hollow portion is filled with an integral resin body that surrounds the small spheres, a lightweight reinforcing structure with excellent water blocking properties can be realized.

  According to the reinforcing structure of the hollow concrete structure according to claim 2, by making the size of each small sphere substantially uniform, the small spheres are regularly arranged in the space, and are formed in the gaps formed by the small spheres. Regularity appears, and the multi-nest resin body that fills and cures in the gaps forms a substantially regular three-dimensional structure or three-dimensional network structure, and the three-dimensional network structure is cured, so that strength against deformation can be obtained. It becomes possible.

  According to the reinforcing structure of the hollow concrete structure according to claim 3, since the filling resin is a fiber reinforced resin containing long fibers, the filling resin becomes a fiber reinforced resin mixed with long fibers such as carbon fibers, The strength after curing increases and the proof stress of the object to be reinforced can be further strengthened.

  According to the reinforcing structure of the hollow concrete structure according to claim 4, since the fabric is adhered to the inner surface of the hollow portion, the filling resin soaks into the fabric and cures, whereby the resin body and the object to be reinforced are The adhesion strength increases, and the proof stress of the object to be reinforced can be further strengthened.

  According to the method for reinforcing a hollow concrete structure according to claim 5, the concrete structure is installed with the opening facing upward, the resin-filled tube is inserted from the opening to the bottom of the hollow, and the hollow is opened from the opening. After filling the part with small spheres, the opening is temporarily covered with a lid formed with a plurality of vent holes smaller than the small spheres, and resin is filled from the hollow part while injecting uncured liquid resin from the resin filling tube The tube is pulled out and the injected resin is cured, so the filling resin enters the gaps between the small spheres from below the hollow part, and the lightweight and high-strength multi-nest resin is cured by embedding the small spheres in the filling resin. The hollow part can be filled with the body.

  According to the method for reinforcing a hollow concrete structure according to claim 6, the concrete structure is installed with the opening facing upward, the resin-filled tube is inserted from the opening to the substantially bottom of the hollow, After filling the hollow part with small spheres, the opening is temporarily covered with a lid formed with a plurality of vent holes smaller than the small spheres, and an uncured liquid resin is injected into the hollow part from the resin filling tube. The resin-filled tube is buried and the injected resin is cured, so that the filled resin enters the gaps between the small spheres in the hollow part, and the small spheres are embedded in the filled resin and hardened integrally. The hollow portion can be filled with the resin body. In addition, by filling and burying the resin-filled tube in the hollow portion used when injecting the filled resin, the complexity of separately storing the resin-filled tube is reduced, the workability is improved, and the cost is reduced. .

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a reinforcing structure for a hollow concrete structure and a reinforcing method for a hollow concrete structure according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a concrete utility pole reinforced by a reinforcing structure according to the present invention.
The reinforcing structure of the hollow concrete structure according to the present embodiment will be described by taking an example in which the object to be reinforced is a concrete electric pole formed with a hollow portion. Note that the reinforcing structure according to the present invention may be reinforced by manholes, sewage pipes, power pipes, communication pipes, etc., which will be described later, or unnecessary hollow portions in the soil, in addition to the utility poles described in this embodiment. .

  The concrete utility pole 100 reinforced with the reinforcing structure according to the present embodiment is erected with the lower base end 11 buried in the ground 13. In the figure, reference numeral 15 denotes a reformed basic region in which cracked stone or the like is embedded. The outer peripheral part 17 of the concrete electric pole 100 is formed in a cylindrical shape from a reinforcing bar (not shown) and concrete. The inner side of the outer peripheral part 17 becomes a hollow part 19, and the hollow part 19 opens as an opening part 21 at the upper end of the outer peripheral part 17.

  A large number of small spheres 23 made of a foamed resin material are filled in the hollow portion 19. The small spheres 23 may be formed of foamed bead-like spheres, or may be formed of amorphous particles such as fibers and long fibers. The average particle size of the small spheres 23 is preferably about 5 to 15 mm. As the foamed resin material, for example, polyethylene terephthalate, polypropylene, polystyrene and the like are preferably used.

  The gap S (see FIG. 2) between the small spheres 23 is filled with an integral resin body 27 obtained by curing the filling resin 25 (see FIG. 2). The small spheres 23 are formed with a specific gravity smaller than that of the filling resin 25. As a material of the filling resin 25, for example, a two-component curable resin such as an epoxy resin, a urethane resin, or a polyester resin can be suitably used.

  The concrete electric pole 100 has a structure in which the hollow portion 19 is replaced with a resin body 27 in which a large number of small spheres 23 are integrally embedded (hereinafter also referred to as “multi-nest resin body”), and is made of a foamed resin material. As the small spheres 23 are embedded, the filling amount of the filling resin 25 is reduced, and the total weight of the object to be reinforced is reduced. In addition, the hollow portion 19 is filled with an integral multi-nest resin body 27 that surrounds the small sphere 23 and has an independent nest, and water-stopping occurs. That is, each nest surrounding the small spheres 23 becomes an independent sealed cavity, and the small spheres 23 are not in communication with each other or are in a point contact state. Therefore, the multifocal resin body 27 does not have air permeability and water permeability. As described above, the multi-nest resin body 27 is a rough structure or a continuous pore (sponge) structure in which the portion of the small sphere 23 is a nest and the filling resin 25 is solidified in a portion corresponding to the gap S. Or a three-dimensional network structure.

  The filling resin 25 is preferably a fiber reinforced resin containing long fibers. Since the filling resin 25 becomes a fiber reinforced resin mixed with long fibers such as carbon fibers, the strength after curing increases, the strength of the multi-nest-like resin body 27, and finally the outer peripheral portion 17 to be reinforced. Strength can be further strengthened.

  Further, a fabric may be attached to the inner surface of the hollow portion 19. As described above, the fabric is adhered to the inner surface of the hollow portion 19, so that the filling resin 25 penetrates into the fabric and cures, and the adhesion strength between the multi-nest resin body 27 and the outer peripheral portion 17 increases, The proof stress of the part 17 can be further strengthened.

  Thus, according to the reinforcing structure of the hollow concrete structure described above, a large number of small spheres 23 made of a foamed resin material are filled into the hollow portion 19 having the opening 21 formed in the concrete electric pole 100, Since the gap S between the small spheres 23 is filled with the resin body 27 in which the filling resin 25 is cured, the hollow portion 19 is replaced with an integrated multi-nest resin body 27 in which a large number of small spheres 23 are embedded. Thus, the outer peripheral portion 17 to be reinforced has a strong resistance to deformation such as compression, bending, bending, and buckling.

  Then, the amount of the filling resin 25 can be reduced by the amount of the foamed resin material embedded, and the object to be reinforced, which has become heavy by filling the hollow portion 19 with concrete, mortar, or resin in the past, is significantly lightened. No deformation or bending stress occurs, and the yield strength can be increased at a low cost. Further, since the total weight of the object to be reinforced becomes light, handling such as transportation becomes easy. Furthermore, since the hollow part 19 is filled with the integral multi-nest resin body 27 surrounding the small spheres 23, a lightweight reinforcing structure with excellent water blocking properties can be realized.

Next, a method for reinforcing the hollow concrete structure will be described.
FIG. 2 is a longitudinal sectional view of a concrete electric pole showing the state of liquid resin injection, FIG. 3 shows a lid (a), and a main part of the concrete electric pole with a hollow portion filled with a multi-nest resin body (b). 4) is a vertical cross-sectional view of a concrete electric pole filled with resin in the lower half of the hollow portion.
In order to reinforce the concrete structure to be reinforced (the concrete electric pole 100 before being filled with the multi-nest resin body 27) W, first, the concrete structure W is installed with the opening 21 facing upward. To do.

  Next, after inserting the resin filling tube 31 from the opening 21 to the bottom of the hollow portion 19, the small spheres 23 are filled into the hollow portion 19 from the opening 21. Thereafter, the opening 21 is temporarily covered with a lid 35 (see FIG. 3A) in which a plurality of vent holes 33 smaller than the small spheres 23 are formed. In the figure, reference numeral 37 denotes a through hole formed in the lid 35 for insertion of the resin filling pipe 31, and 39 denotes a hose connecting the resin filling pipe 31 and a resin supply means (not shown).

  Next, the resin-filled tube 31 is gradually pulled out from the resin-filled portion of the hollow portion 19 while injecting the uncured liquid-filled resin 25 from the resin-filled tube 31. Since the specific gravity of the small sphere 23 is smaller than that of the filling resin 25, buoyancy is generated due to the injection of the filling resin 25, so that the small sphere 23 tends to rise. However, the small sphere 23 is pressed by the lid 35 attached to the opening 21. The gap S is gradually filled. When the filling resin 25 is filled up to the upper end of the hollow portion 19 and the resin filling tube 31 is pulled out from the lid 35, the through hole 37 is closed and the injected resin is cured by curing for a predetermined time.

  As a result, the filled resin 25 enters the gap S between the small spheres 23, and the multi-lobed resin body 27 shown in FIG. It will be formed inside.

  Therefore, according to the method for reinforcing a hollow concrete structure, the concrete structure W is installed with the opening 21 facing upward, and the resin-filled tube 31 is inserted from the opening 21 to the bottom of the hollow portion 19. After filling the hollow portion 19 with the small sphere 23 from 21, the opening 21 is temporarily covered with a lid 35 having a plurality of vent holes 33 smaller than the small sphere 23, and uncured liquid from the resin filling tube 31. The resin-filled tube 31 is pulled out from the hollow portion 19 while injecting the resin, and the injected resin is cured, so that the filled resin 25 enters the gap S between the small spheres 23 from below the hollow portion 19, and the small sphere 23 enters the filled resin 25. Can be formed to form a light weight and high strength multi-nest resin body 27 which is cured integrally. As a result, the entire hollow portion 19 can be filled with the homogeneous multi-nest resin body 27.

  As shown in FIG. 4, the concrete electric pole may be one in which the filling resin 25 is filled only in the lower half of the hollow portion 19. In this way, if only the lower half of the hollow portion 19 is filled with the multi-nest resin body 27, the amount of injected resin can be reduced, and the weight of the upper half concrete structure can be prevented from increasing. Efficient and inexpensive reinforcement is possible.

  In the above-described reinforcing method, the example in which the filling resin 25 is injected into the gap S between the small spheres 23 previously filled in the hollow portion 19 has been described. However, the reinforcing method according to the present invention is small in liquid resin before injection. A sphere 23 may be mixed and a small sphere mixed resin of the small sphere 23 and a liquid resin may be injected.

Next, a modification of the reinforcing structure according to the present invention will be described.
In the above embodiment, the case where the concrete structure W is a concrete utility pole has been described as an example. However, the reinforcing structure according to the present invention is a manhole or sewer pipe that is no longer used as another concrete structure. The present invention can also be applied to objects to be reinforced that occupy unnecessary space in the soil, such as power pipes and communication pipes.
FIG. 5 is a longitudinal sectional view of the manhole bottom reinforced by the reinforcing structure according to the present invention.
In the manhole bottom portion 40, an annular filling space 45 is formed inside the standing pipe 43 whose lower end is closed by the bottom plate 41, and a lining plate 47 is provided therein. After filling the filling space 45 with the small spheres 23, Filling resin 25 is injected. Also in this case, the upper opening 49 of the filling space 45 is covered with a lid (not shown). Further, as described above, the small sphere mixed resin may be directly injected into the filling space 45.

  According to the manhole bottom 40, the filling space 45 is replaced with an integrated resin body 27 in which the small spheres 23 are embedded, and the pipe 43 to be reinforced is compressed, bent, bent, buckled, or the like. Becomes more resistant to deformation. In addition, since the filling space 45 is filled with the integral multi-nest resin body 27 surrounding the small spheres 23, a lightweight reinforcing structure with excellent water blocking properties can be realized.

FIG. 6 is a perspective view of a tubular body reinforced by the reinforcing structure according to the present invention.
In the sewage pipe 50, an annular filling space 53 is formed inside the concrete pipe 51 and a lining plate 55 is provided. After filling the filling space 53 with the small spheres 23, the filling resin 25 is injected. . Also in this case, the small sphere mixed resin may be directly injected into the filling space 53 as described above.

  According to the sewage pipe 50, the filling space 53 is replaced with the integrated resin body 27 in which the small spheres 23 are embedded, and the concrete pipe 51 to be reinforced is compressed, bent, bent, or buckled. It becomes strong against deformation. In addition, since the filling space 53 is filled with the integral multi-nest resin body 27 surrounding the small spheres 23, a lightweight reinforcing structure excellent in water-stopping can be realized.

  Furthermore, although not shown in the drawings, the present invention can be obtained by pouring and filling the above-mentioned small sphere mixed resin into tubes or cavities that occupy unnecessary space in the soil. It can also be applied to prevent accidents such as damage due to aged deterioration of the pipe body and road collapse due to collapse of the hollow portion by filling the hollow portion or the hollow portion with the multi-nest resin body 27.

  Further, although not shown in the drawings, in each of the above embodiments, the resin-filled tube is gradually inserted while the resin-filled tube is inserted into the hollow portion or the hollow portion, and the liquid-filled resin is injected from the resin-filled tube. Although an example of pulling out has been described, the resin-filled tube may be buried, that is, left in the hollow portion or the hollow portion, and the filled resin may be cured. This reduces the complexity of separately storing the resin-filled pipe used for each operation, improves the workability and the like, and leads to cost reduction.

It is a longitudinal cross-sectional view of the concrete utility pole reinforced with the reinforcement structure which concerns on this invention. It is a longitudinal cross-sectional view of the concrete utility pole showing the injection | pouring condition of liquid resin. It is the longitudinal cross-sectional view which represented the principal part of the concrete electric pole with which the cover body was (a) and the hollow part was filled with the multi-nest-like resin body in (b). It is a longitudinal cross-sectional view of the concrete electric pole with which the lower half of the hollow part was filled with resin. It is a longitudinal cross-sectional view of the manhole bottom part reinforced with the reinforcement structure which concerns on this invention. It is a perspective view of a tubular body reinforced by the reinforcing structure according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 19 ... Hollow part 21 ... Opening part 23 ... Small spherical body 25 ... Filling resin 27 ... Multi nest-like resin body 31 ... Resin filling pipe 33 ... Vent hole 35 ... Lid body S ... Crevice between small spherical bodies W ... Concrete structure

Claims (6)

In a hollow portion having an opening formed in a concrete structure, a large number of small spheres made of a foamed resin material are filled,
A reinforcing structure of a hollow concrete structure, wherein a gap between the small spheres is filled with an integral resin body obtained by curing a filling resin.   2. The reinforcing structure for a hollow concrete structure according to claim 1, wherein the small spheres are formed to have substantially the same diameter.   The reinforcing structure for a hollow concrete structure according to claim 1 or 2, wherein the filling resin is a fiber reinforced resin containing long fibers.   The reinforcing structure for a hollow concrete structure according to claim 1, wherein a fabric is adhered to an inner surface of the hollow portion. A large number of small spheres are filled into a hollow portion having an opening formed in a concrete structure,
A method for reinforcing a hollow concrete structure in which the gaps between the small spheres are filled with an integral resin body obtained by curing a filling resin,
Install the concrete structure with the opening facing up,
Insert the resin-filled tube from the opening to the bottom of the hollow part,
After filling the hollow portion with the small sphere from the opening, the opening is temporarily covered with a lid formed with a plurality of vent holes smaller than the small sphere,
Pulling out the resin-filled tube from the hollow portion while injecting uncured liquid resin from the resin-filled tube,
A method for reinforcing a hollow concrete structure, wherein the injected resin is cured. A large number of small spheres are filled into a hollow portion having an opening formed in a concrete structure,
A method for reinforcing a hollow concrete structure in which the gaps between the small spheres are filled with an integral resin body obtained by curing a filling resin,
Install the concrete structure with the opening facing up,
Insert the resin-filled tube from the opening to the bottom of the hollow part,
After filling the hollow portion with the small sphere from the opening, the opening is temporarily covered with a lid formed with a plurality of vent holes smaller than the small sphere,
Injecting an uncured liquid resin from the resin-filled tube, filling the hollow portion with the resin-filled tube and leaving it,
A method for reinforcing a hollow concrete structure, wherein the injected resin is cured.

Images