JP4233434B2 - Repair method for concrete structures - Google Patents

Description

  The present invention relates to a method for repairing a concrete structure having a hollow portion such as a bridge.

If a concrete structure is used for a long time, the concrete deteriorates and may need repair. In particular, in places near the coastline that are affected by seawater or where snow melting materials are used, chlorine penetrates into the concrete, and the reinforcing bars arranged for reinforcement may corrode. As corrosion of the reinforcing bars progresses, the surroundings of the reinforcing bars expand and cracks occur in the concrete, or in some cases, the concrete peels off. If the corrosion of the reinforcing bar is found in the preliminary survey, use a water jet to remove the concrete to repair the corroded part, and conduct inspection and repair by exposing the reinforcing bar. It was necessary to repair and reinforce the corroded reinforcing bars, and then restore them by spraying concrete (see Patent Documents 1 and 2).
JP-A-60-55106 JP 2002-167777 A

  In Patent Document 1, as a method of repairing a bridge, “exposed corroded existing steel in concrete in a deteriorated part is exposed, and after the necessary anticorrosion treatment is applied to the existing steel, reinforcing steel is applied around the bridge girder including the deteriorated part. Place and fix this reinforcing steel to the bridge girder, place the formwork around the reinforcing steel at a predetermined distance from the bridge girder and fix this formwork to the bridge girder, and then between this formwork and the bridge girder By filling the gap formed in the gap with an aggregate, and then injecting the injection material into the gap and hardening it ”(Claim 1), and by“ using an artificial lightweight aggregate as the aggregate ” It is also described that the increase in weight after repair can be reduced (Claim 3, page 3, upper left column, lines 15 to 16).

  In Patent Document 2, as a method of reinforcing the bottom surface of a reinforced concrete floor slab, “the part of concrete that requires reinforcement of the existing concrete floor slab is removed to at least both ends of the reinforcing part to the back side of the reinforcing bar, and the reinforcing bar is exposed. Then, a reinforcing reinforcing bar is connected to the exposed reinforcing bar with a connector, and the reinforcing part is sprayed with a short fiber reinforced mortar or concrete to increase the thickness "(Claim 1), and the concrete requiring reinforcement is removed. By using a water jet nozzle device, the cutting depth can be reliably controlled by spraying water jets from a pair of nozzles so that the water jets collide with each other. It is also described that it can be surely removed up to the back side of the above (claims 3 and 4, paragraph [0020]).

By the way, in order to reduce the weight of the bridge slab, etc., a hollow portion is made using a cylindrical iron pipe or the like when placing the slab concrete (see [Prior Art] in Patent Document 3). In the same way, repairs were carried out. However, if there is a hollow part like floor slab concrete, the concrete may be pierced with a water jet to make a hole in the hollow part. In the past, repair was done by applying a mold to the holed part.
In addition, it is also known to reduce the dead weight by filling urethane foam into a bridge slab or the like instead of using the above-described cylindrical iron pipe or the like (see Patent Document 3).
JP-A-5-222707

  In Patent Document 3, as a method for constructing a composite floor slab bridge, “the cross section perpendicular to the bridge axis direction has an upward U-shape, and the bottom surface of the steel shell has a U-shape. T-ribs with a T-shaped cross section with a height of up to 2 mm are fixedly erected by welding, etc., and foamed and solidified by filling closed cell foamed rigid urethane foam between the T ribs and between the T ribs and the side plates of the steel shell. This rigid foamed urethane foam is bonded and solidified to the inner surface of the steel shell and the T-rib belly plate surface to form a rigid foamed urethane layer, and concrete is placed on the upper surface of the rigid foamed urethane layer to form a synthetic floor slab. (Claim 2) is described, but it is not shown that urethane foam is used for repairing a synthetic floor slab (concrete structure) having a hollow portion.

In addition, when molding concrete having a hollow portion, it is also known that air is poured into a bag-like material to form a mold (see Patent Documents 4 and 5).
Japanese Patent Laid-Open No. 10-196108 JP 2000-45443 A

  In Patent Document 4, as a concrete forming method, “at least a part of a concrete surface to be formed is formed by a dam plate held by an air mat that is expanded by compressed air, and the concrete is poured into a required portion. The air mat is made of a bag-like film formed of reinforced chemical fiber or the like ”(Claim 1). (Paragraph [0019]) does not show the use of an air mat (bag-shaped formwork) for repairing a concrete structure having a hollow portion.

  In Patent Document 5, as a synthetic floor slab manufacturing method, “an airbag that expands and contracts by supplying and discharging air is provided, and reinforcing bars are arranged in a concrete formwork in a factory and the expanded airbag is made concrete. Place it in contact with the bottom wall of the formwork or at a place away from the bottom wall, and then place concrete in the concrete formwork and harden it to obtain a reinforced concrete body. After removing the air from the air bag, the air bag is removed from the reinforced concrete body to obtain a void slab having an open cavity on the front or back surface of the reinforced concrete body. The void slab is placed on the place where the composite slab is to be constructed, and concrete is placed on this to create a concrete layer. Although a synthetic floor slab with an integrated cleat layer is constructed "(Claim 6) is described, an air bag (bag-like shape) is used for repairing a synthetic floor slab (concrete structure) having a hollow portion. The use of formwork is not shown.

When repairing a concrete structure with a hollow part such as a bridge, the repair was conventionally performed by applying a mold to the holed part of the hollow part as described above. It was difficult to hit the formwork. Moreover, when repairing sprayed concrete or the like without applying a formwork, there is a problem that the concrete enters into the hollow portion and the structure becomes heavy.
The present invention solves the above problems, and in a repair method for a concrete structure having a hollow portion, even if the hollow portion has a hole, the reinforcing material such as a reinforcing bar does not become an obstacle, and the hollow portion It is an object to provide a repairing method so that concrete does not enter the wall.
The present invention intends to solve the above-mentioned problems by applying foamed urethane and bag-shaped molds, which have been conventionally used when molding concrete, to repair concrete structures.

In order to solve the above problems, the following means are adopted in the present invention.
(1) In a concrete structure repairing method for repairing a concrete structure having a hollow part, after removing deteriorated concrete, the hollow part is filled with a filler in advance through a bag-shaped mold and then repaired. A method for repairing a concrete structure characterized by the above.
(2) The method for repairing a concrete structure according to (1) , wherein the filling material filled in the bag-shaped mold is urethane foam.
(3) The method for repairing a concrete structure according to (1) , wherein the filling material filled in the bag-shaped mold is a fluid.
(4) The method for repairing a concrete structure according to (3) , wherein the fluid is a gas.
(5) The method for repairing a concrete structure according to (3) , wherein the fluid is a liquid.
(6) The method for repairing a concrete structure according to (3) , wherein the fluid is slurry.
(7) The method for repairing a concrete structure according to any one of (1) to (6) , wherein the repair is performed by spraying mortar or concrete.
(8) The method for repairing a concrete structure according to any one of (3) to (7) , wherein the fluid is removed after the repair.

  In the present invention, when repairing a concrete structure having a hollow portion, even if there is a reinforcing material such as a reinforcing bar, the workability is good, the repair material can be prevented from entering the hollow portion, and it can be restored to its original state. There is an effect.

  Although it does not specifically limit as a filler used by this invention, It needs to be lightweight. An example is urethane foam. Urethane foam is a material that uses the property of foaming and curing when carbon dioxide gas is generated by the reaction of polyol and isocyanate to cure, and is mainly used for ground reinforcement during tunnel excavation. Available.

  The foaming ratio of urethane has a foaming ability of up to about 30 times. If the expansion ratio is large, the specific gravity after curing is light, the amount of material used is small, and the economy is excellent. However, if the expansion ratio is high, the strength is low, and it cannot be withstood during water jet concrete chipping. It is necessary to withstand the concrete debris of the water jet, and it is necessary that the spray material used as repair spray does not enter the hollow portion. These conditions are balanced by an expansion ratio of about 10 to 20 times.

  Moreover, welding may be used for repairing reinforcing bars. At this time, there is a risk that urethane foam burns and toxic gases are generated. The foamed urethane used is preferably an inorganic composite that is difficult to burn. Inorganic composite materials include those using water glass and those using alkali metal carbonates. Examples of the alkali metal carbonate include potassium carbonate and sodium carbonate. Inorganic composite materials are self-extinguishing, and even if they are partially burned by welding reinforcing bars, the whole will not burn.

  The procedure for filling the filler includes before and after removing the deteriorated concrete. Before removing, drill holes in the concrete with a diamond cutter etc. at intervals of about 1m and fill with filler. In this case, a formwork is unnecessary and efficiency is high.

  After that, the concrete deteriorated by the water jet is removed. Next, after repairing and reinforcing a reinforcing material such as a reinforcing bar, it is repaired by a method such as spraying mortar or concrete. A method of spraying polymer cement mortar is preferred.

  When pouring after removing the deteriorated concrete, a formwork for preventing the filler from coming out of the hollow portion is required. If there are reinforcing materials such as reinforcing bars, the formwork cannot be easily attached. In the present invention, in order to solve this problem, after removing the deteriorated concrete using a bag-like material as a mold, it is put into a hollow portion from an opened hole, and a filler is injected into the bag-shaped mold.

  The bag to be used may be any material that achieves the purpose, such as plastic such as vinyl, cloth, rubber, or paper. The bag is preferable because it is easily filled with a bag slightly larger than the hollow portion. In addition, if the inner pressure is applied, the shape and size are not particularly limited as long as it expands somewhat. A material that rubs against the hollow portion and hardly moves when it swells is preferable.

  The material to be injected into the bag is preferable because urethane foam is lightweight and self-hardening. In addition to the urethane foam, the bag can be filled with a fluid such as air, a gas such as nitrogen, a liquid such as water, a slurry (suspension fluid) such as a cement paste, a foam mortar or a plastic mortar, or a plastic injection material. It is preferable from the viewpoint of weight reduction that these fillers are extracted and hollow after the spray repair is performed. It is effective to apply some kind of reinforcing material when the purpose cannot be achieved with a bag-shaped formwork alone because a hole is formed by spraying mortar or concrete or the like. In this case, it is preferable to have a variability that is easy to put in even if there are reinforcing materials such as reinforcing bars.

(Reference example)
Reinforcement in floor slab concrete was corroded by the effect of using snow melting material, and the bottom concrete peeled off. In order to carry out repair work by spraying the lower surface, holes with a diameter of 50 mm were drilled in advance at intervals of 1 m in one hollow part. Using this hole, a PVC pipe was inserted, and urethane injection was performed (the urethane used was a 4-fold foamed product manufactured by Electrochemical). After the urethane injection was completed, the bottom surface of the floor slab was clawed and the bottom steel bar was exposed using a water jet. The rebar was severely corroded. At this time, a part of the hollow pipe that was severely corroded was exposed and shaved with water pressure water. Urethane foam injected in advance from the corroded portion was confirmed. A part of the urethane foam was cut out and the specific gravity was measured and found to be 0.3.
Reinforcing bars in which aramid fibers that are resistant to corrosion were hardened with resin were set, and repair work was carried out by spraying polymer cement mortar. There was no need to attach a new formwork, and the sprayed mortar did not enter the interior of the hollow part due to the effect of urethane filling.

One hollow portion was not subjected to any treatment in advance, and the concrete was beaten with a water jet. Corrosion was severe and holes were formed in most of the hollow parts. The urethane of Example 1 was injected using this hole. Since there was no formwork, the urethane being injected leaked out, so it was pressed with a cloth to prevent leakage and the hollow part was filled with urethane. In particular, vinyl sheets and cloth were applied to large holes in advance to replace the simple formwork so that the urethane foam to be injected did not leak.
Thereafter, spraying was performed in the same manner as in Example 1. The result was good.

As in Example 2, no treatment was performed in advance and a water jet was applied. Similarly, a hole was opened in the hollow part. Using this hole, a plastic bag having a diameter of about 85 cm that is slightly larger than the hollow portion was put, and the urethane foam of Example 1 was injected into the inside. The bag was filled with urethane and the hollow part was filled.
Thereafter, polymer mortar was sprayed without forming a mold. The sprayed mortar did not enter the hollow part, and construction was possible without problems.

A bag was set in the same manner as in Example 3, and water, air, cement paste, foamed mortar, and plastic mortar were poured into the bag instead of urethane foam. After injection, the mortar was sprayed after pressure was applied so that the injected material did not leak or the inlet was sealed to prevent the bag from shrinking. Construction was possible without mortar entering the hollow part.
After spraying, the contents were removed from the inlet. By this work, the hollow part was made and the overall weight could be reduced as before repairing.

A similar bag was made using cloth, rubber and paper as the material and type of the bag, and the same test work was carried out.
Construction was carried out in the same manner as in Example 4. Depending on the injection material, some of the injection material leaked from the bag, but if the bag was sufficiently swollen, it could be constructed without problems.

Claims (8)

In a concrete structure repairing method for repairing a concrete structure having a hollow part, after removing deteriorated concrete, the hollow part is filled with a filler in advance through a bag-shaped mold , and then repaired. Repair method for concrete structures. The method for repairing a concrete structure according to claim 1 , wherein the filler filled in the bag-shaped mold is urethane foam. 2. The method for repairing a concrete structure according to claim 1 , wherein the filling material filled in the bag-shaped mold is a fluid. The method for repairing a concrete structure according to claim 3 , wherein the fluid is a gas. The method for repairing a concrete structure according to claim 3 , wherein the fluid is a liquid. The method for repairing a concrete structure according to claim 3 , wherein the fluid is a slurry. It repairs by spraying mortar or concrete, The repair method of the concrete structure as described in any one of Claims 1-6 characterized by the above-mentioned. The method for repairing a concrete structure according to any one of claims 3 to 7 , wherein the fluid is removed after the repair.