Repair and reinforcement methods for concrete tanks

Abstract

The present invention aims to reduce the cost of repairing existing concrete water purification tanks, thereby shortening construction time and reducing the workload. [Solution] The system employs a configuration comprising: a batten fixing step of fixing stainless steel battens to a concrete tank; a stainless steel plate fixing step of fixing multiple stainless steel plates to the battens fixed in the batten fixing step; a stainless steel plate welding step of butt welding the multiple stainless steel plates fixed to the battens in the stainless steel plate fixing step; a vacuum testing step of performing a vacuum test to check for water leakage in the welded portion in the stainless steel plate welding step; a filling step of filling the space between the concrete tank and the multiple stainless steel plates created by the battens with non-shrink mortar; and a pressure resistance testing step of performing a pressure resistance test to confirm whether it can withstand the pressure and load expected during actual use.

Description

Technical Field

[0001] The present invention relates to a method for repairing and reinforcing a concrete tank, and more particularly to a construction method in which the inner wall is formed of a stainless steel plate and not only repair but also reinforcement is carried out.

Background Art

[0002] Factories and facilities built during the period of high economic growth have generally passed 50 years, and water leakage from water purification tanks due to concrete deterioration is often seen. Water in the tank is in a dripping state, and there are not a few cases where it is noticed only when a high water bill is billed. So far, specialized contractors have been responsible for the repair work, but in many cases, the content of the repair work cannot be said to be sufficient. Here, the conventional method will be explained. For the repair of existing concrete water purification tanks, epoxy resin materials and mortar concrete are used, but these have problems such as high cost and remaining water leakage after repair. In addition, such existing methods also leave problems that need to be solved, such as a long construction period.

[0003] In the conventional repair of concrete tanks that have cracked or the like due to aging or the influence of an earthquake and require repair, epoxy resin materials and mortar concrete are used, but these have problems such as high cost and remaining risk of water leakage after repair. In addition, epoxy resin is derived from petroleum, and there are concerns about the emission of volatile organic compounds (VOCs). In waste treatment, it is not suitable for incineration due to its flame retardancy and is difficult to recycle. Therefore, in the present invention, by introducing an inner wall repair method using a stainless steel plate, the risk of water leakage is completely eliminated, and a repair service that enables inexpensive and long-term maintenance can be provided.

[0004] In light of the above-mentioned problems, various technical proposals have been made in the past. For example, there is a technology titled "Reinforcement Structure for Concrete Water Tanks" (see Patent Document 1). Specifically, the objective is to "provide a reinforcement structure for concrete water tanks that can reinforce concrete walls with a simple configuration, improve seismic resistance, and suppress the reduction of water storage capacity," and the solution is to "construct the bottom wall and side walls constituting the water tank with concrete and reinforcing mesh. Adhere to the upper surface of the bottom wall and the inner surface of the side walls with an epoxy resin adhesive. Weld the butt joints of each reinforcement panel." The invention described in Patent Document 1 is similar to the present invention in that the inner wall is covered with a stainless steel panel. However, the invention in Patent Document 1 leaves some issues regarding environmental protection because the stainless steel panel is attached to the inner wall using an adhesive.

[0005] Furthermore, there is a technology with the invention title "Pool Repair Method" (see Patent Document 2). Specifically, "Conventional lining methods are unsuitable for cases with a high degree of damage or many damaged areas, and regular repairs are necessary even for bulging that occurs in the early stages of expected corrosion of the bottom surface. Moreover, FRP methods have the problem of being troublesome to perform painting, drying, and other related work, requiring a lot of time and money for the work. This invention aims to provide a pool repair method that can be performed quickly and inexpensively even if the frequency of damage is high or there are many damaged areas, taking the above-mentioned problems into consideration," and the solution is "a pool repair method characterized by using an aluminum plate as the base material of at least the bottom surface, bonding a thin stainless steel plate to at least the upper surface of the repair area on the bottom surface, riveting the necessary parts of the stainless steel plate, bonding glass cloth to these upper surfaces, and then painting the upper surface." However, the invention described in Patent Document 2 differs in its fastening method, which involves bonding a thin stainless steel plate to at least the upper surface of the repair area on the bottom surface and riveting the necessary parts of the stainless steel plate. Furthermore, it involves bonding glass cloth to these upper surfaces and then painting the upper surface. Therefore, although it is a concrete structure, the object of repair and the technical means for solving the problem are different.

[0006] Furthermore, there is a technology with the title of "Water Tank and Method for Repairing a Water Tank" (see Patent Document 3). Specifically, the problem is to "provide a water tank structure and repair method particularly suitable for repairing existing concrete water tanks, relating to a method for repairing a water tank that has leaked water," and the solution is to "create a bag of a size to be attached to the inner surface (bottom surface and inner wall surface) of an existing concrete structure that forms a water tank by joining together a plurality of watertight sheets cut to predetermined dimensions, or by folding a single watertight sheet, fold this bag and place it inside the existing concrete structure, spread out the sheet that will become the bottom of the bag inside, assemble a frame of a size to be attached to the inside of this bag on top of the spread-out bottom of the bag, pull up the sheet that will become the side wall of the bag along the outer surface of the frame, and secure its upper edge to the upper edge of the frame with a rope or fitting." However, the invention described in Patent Document 3 uses a watertight sheet bag and a frame made of pipes for repair purposes, which is a different technical means to be solved from the present invention, which covers the inner wall and the upper surface of the floor with stainless steel plates. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2010-150839 [Patent Document 2] Published Japanese Patent No. 2-190574 [Patent Document 3] Japanese Patent Publication No. 2013-230818 [Overview of the project] [Problems that the invention aims to solve]

[0008] Currently, epoxy resin materials are used to repair existing concrete water purification tanks and the like, but these are costly and require long construction periods. This invention aims to reduce costs, shorten construction time, and alleviate the workload. [Means for solving the problem]

[0009] The present invention relates to a method for repairing and reinforcing a concrete tank, which has a stainless steel inner wall installed inside, and adopts a configuration comprising: a batten fixing step of fixing stainless steel battens to the concrete tank; a stainless steel plate fixing step of fixing a plurality of stainless steel plates to the battens fixed in the batten fixing step; a stainless steel plate welding step of butt welding the plurality of stainless steel plates fixed to the battens in the stainless steel plate fixing step; a vacuum test step of performing a vacuum test to check for water leakage in the welded portion in the stainless steel plate welding step; a filling step of filling the space between the concrete tank and the plurality of stainless steel plates created by the battens with non-shrink mortar; and a pressure test step of performing a pressure test to check whether it can withstand the pressure and load expected during actual use. [Effects of the Invention]

[0010] The method for repairing and reinforcing concrete tanks according to the present invention exhibits excellent effects, such as completely preventing water leakage from water purification tanks and significantly improving their durability.

[0011] Furthermore, the concrete tank repair and reinforcement method according to the present invention offers the excellent advantage of shortening the construction period compared to repairs using epoxy resin or mortar concrete.

[0012] Furthermore, the concrete tank repair and reinforcement method according to the present invention exhibits the excellent effect of contributing to the maintenance of sustainable water supply infrastructure. [Brief explanation of the drawing]

[0013] [Figure 1] This flowchart shows the basic workflow of the concrete tank repair and reinforcement method according to the present invention. [Figure 2] This is a structural diagram illustrating the reinforcement structure of a concrete tank in the concrete tank repair and reinforcement method according to the present invention. [Figure 3]This is an explanatory cross-sectional view illustrating the reinforcement structure of a concrete tank according to the method for repairing and reinforcing concrete tanks according to the present invention. [Figure 4] This is a process diagram illustrating each step of the concrete tank repair and reinforcement method according to the present invention. [Modes for carrying out the invention]

[0014] Cracks and leaks in concrete tanks are caused by deterioration over time, such as the peeling of the paint and underlying mortar on the surface of the concrete tank. Furthermore, the decomposition of pollutants and organic matter in the concrete tank can generate hydrogen sulfide, leading to sulfuric acid corrosion of the concrete surface, which can cause cracks and leaks. Additionally, because concrete is alkaline, organic acids generated within the tank can accelerate corrosion. The concrete tank repair and reinforcement method according to the present invention is a method for repairing and reinforcing a concrete tank in which a stainless steel inner wall is installed, and its greatest feature is that it comprises a batten fixing step of fixing stainless steel battens to the concrete tank, a stainless steel plate fixing step of fixing a plurality of stainless steel plates to the battens fixed in the batten fixing step, a stainless steel plate welding step of butt welding the plurality of stainless steel plates fixed to the battens in the stainless steel plate fixing step, a vacuum test step of performing a vacuum test to check for water leakage in the welded portion in the stainless steel plate welding step, a filling step of filling the space created between the concrete tank and the plurality of stainless steel plates by the battens with non-shrink mortar, and a pressure resistance test step of performing a pressure resistance test to check whether it can withstand the pressure and load expected during actual use. The following will be explained based on the drawings. Note that the overall shape and dimensions of the concrete tank repair and reinforcement method according to the present invention are not limited to the description below, and the shapes of each part can be changed within the scope of the technical idea of ​​the present invention, that is, within the range of shapes and dimensions that produce the same effect.

[0015] FIG. 1 is a flowchart showing the basic operation flow of the method 1 for repairing and reinforcing a concrete tank according to the present invention. Hereinafter, each step will be described in detail.

[0016] The step A of fixing the cross members is a step of fixing the cross members 10 for fixing the stainless steel plate 30 to the concrete tank 20 to the concrete tank 20 using anchor bolts. It is desirable to use all anchors or chemical anchors (registered trademark) for such anchor bolts. In the case of all anchors, those made of SUS304 stainless steel are preferable. Such all anchors are a kind of construction anchor that is inserted into a drilled hole in the concrete and the internal wedge is expanded for fixing. Also, chemical anchors (registered trademark) are also suitable. This is a post-construction anchor that puts a resin capsule or injection material into a hole drilled in the concrete and strongly fixes bolts or deformed reinforcing bars by chemical reaction.

[0017] The step B of fixing the stainless steel plate is a step of arranging the stainless steel plate 30 on the cross members 10 for positioning.

[0018] The step C of welding the stainless steel plates is a step of butt-welding or fillet-welding the connected stainless steel plates 30 together, which is performed by general TIG welding or MIG welding. As the material for such welding, welding rods and wires dedicated to stainless steel (such as SUS304) are used. Since the thermal expansion rate is high and it is easy to distort, it is important to perform the welding at a low current for a short time to suppress the thermal influence. It is a process that requires techniques and experience such as precise current control, appropriate cooling rate, and selection of welding rods to easily form the difficulties of heat management (high thermal expansion rate and easy to distort), the property of being easily oxidized, and the brittle structure (martensitization, etc.).

[0019] The step D of vacuum testing is a step of inspecting for water leakage from the welded portion in the step C of welding the stainless steel plates, and is for detecting defects in the welded portion. Specifically, it is a step of applying a dedicated vacuum box to the welded portion and the like, making the inside negative pressure, and observing the bubbles of the foaming liquid applied to the surface to find leaks.

[0020] Filling process E is a process of filling non-shrinking mortar 50 into the gap between the fixed stainless steel plate 30 and the inner wall N of the concrete tank 20. Since the non-shrinking mortar 50 has good permeability, it penetrates even in a small gap.

[0021] The pressure resistance test process F is a process for checking whether the concrete tank can withstand the pressure and load assumed during actual use. Specifically, the concrete tank is filled with water and pressurized to check for leaks or damage.

[0022] Figure 2 is a structural explanatory diagram for explaining the reinforcement structure of the concrete tank 20 in the concrete tank repair and reinforcement method 1 according to the present invention. According to the concrete tank repair and reinforcement method 1 according to the present invention, not only the repair effect of the stainless steel plate 30 on the inner wall N of the cracked concrete tank 20 such as crack H, but also a stainless steel wall having a strong frame body can be installed inside, indicating that the reinforcement effect is high.

[0023] The concrete layer K is a layer forming the body part made of box-shaped concrete that forms the concrete tank 20 in which cracks or the like have occurred due to aging, earthquake damage, etc. and repair is required, and refers to a composite material (cement concrete) in which aggregates are hardened with cement paste (paste obtained by adding water to cement). Although not shown in the drawings, since concrete can withstand compressive force but is weak in tensile force, it is often used as reinforced concrete with steel bars inserted into the concrete rather than using concrete alone. By inserting steel bars having the same thermal expansion rate as concrete, the steel bars can bear the tensile force and sufficient strength can be provided against both forces.

[0024] The stainless steel layer S is a layer of stainless steel formed inside the non-shrink mortar layer M that covers the inner wall N and the upper surface of the floor Y of the concrete tank 20 by welding together multiple stainless steel plates 30. Stainless steel, although mainly composed of iron, forms an oxide film called a passive film on its surface, giving it rust-resistant properties. Furthermore, by adding nickel (Ni) and other elements, its corrosion resistance can be improved, allowing it to be used outdoors for long periods of time. Because it does not deteriorate easily even when exposed to ultraviolet rays and wind and rain, it is used in bridges, building exteriors, and ship parts. It has excellent corrosion resistance, strength, and light resistance, and it is desirable to form it inside the concrete tank 20.

[0025] The non-shrink mortar layer M is a layer formed of non-shrink mortar 50 that covers the inner wall N and the upper surface of the floor Y of the concrete tank 20, and is formed in the space 40 between the concrete tank 20 and the stainless steel plate 30.

[0026] Cracks (H) are almost always present in concrete structures, albeit to varying degrees. The causes of cracking are diverse, including "drying shrinkage cracks," "cracks due to cement hydration heat," "cracks due to uneven settlement," and concrete deterioration phenomena such as "alkali-aggregate reaction," "freeze-thaw cycles," "carbonation," "chloride penetration," and "fatigue." The cause and the degree of the crack (H) can determine whether there is a problem or if immediate action is required. Concrete is inherently prone to cracking because it is strong in compression but weak in tension and has low deformation capacity. Cracks (H) occur when tensile stress acts on the concrete due to various factors, causing strain that exceeds the concrete's deformation capacity. As cracks (H) progress, they can lead to water leakage and, in the worst case, collapse, necessitating repair.

[0027] Efflorescence occurs when soluble components in concrete dissolve in water and react with carbon dioxide in the air as the water evaporates from the surface, precipitating as calcium carbonate. It is also known as the white efflorescence phenomenon. Efflorescence does not appear suddenly, nor does it cause a rapid deterioration of the structure, so in that sense, it may not be a dangerous deterioration phenomenon that requires urgent repair. However, since it is certain that water is seeping in from somewhere and steadily rusting the reinforcing steel inside, it is a phenomenon that can easily lead to further deterioration if left untreated, potentially resulting in accidents, and repairs can be carried out in the early stages to reduce repair costs.

[0028] The stainless steel battens 10 are frames used to form a non-shrink mortar layer M between the concrete tank 20 and the stainless steel plate 30. The battens 10 used in the concrete tank repair and reinforcement method 1 according to the present invention are stainless steel square pipes or channel materials. Specifically, for example, if stainless steel square materials with a width of 40 mm and a thickness of 20 mm are used, the thickness of the non-shrink mortar 50 to be poured can be set to 20 mm.

[0029] Concrete tanks 20 are facilities, such as rainwater storage and infiltration tanks, that temporarily store rainwater or allow it to infiltrate into the ground to prevent it from flowing into rivers or sewers. They are characterized by their robust structure and high durability, but prolonged use can lead to deterioration, resulting in cracks H and efflorescence R. Therefore, concrete tanks 20 that exhibit such cracks H require repair or reinforcement.

[0030] Multiple stainless steel plates 30 are used to make the inner wall N and the upper surface of the floor Y of the concrete tank 20 out of stainless steel. Specifically, for example, using SUS304HL plates with a width of 500 mm, a length of 3000 mm, and a thickness of 3 mm or 2.5 mm is preferable in terms of workability and strength. Stainless steel, although its main component is iron, forms an oxide film called a passive film on its surface, giving it the property of being resistant to rust. Furthermore, corrosion resistance can be improved by adding nickel (Ni), etc. It can also be used outdoors for long periods of time and does not deteriorate easily even when exposed to ultraviolet rays and wind and rain, so it is used in bridges, building exteriors, and ship parts. It can be said to have excellent corrosion resistance, strength, and light resistance, and long-term durability. A disadvantage is that it may be weak against chlorine and strong acids, so it is necessary to select the appropriate type.

[0031] Space 40 is the space created between the inner wall N or the upper surface of the floor Y of the concrete tank 20 and the stainless steel plate 30, and is filled with non-shrink mortar 50. Specifically, it refers to a spatial area partitioned by battens 10, with a thickness of 30 mm, a width of 500 mm, and a length of 3000 mm.

[0032] Non-shrink mortar 50 is a mortar that does not shrink during hardening, unlike ordinary cement mortar, and has high penetration into gaps. Non-shrink mortar 50, in particular, known as grout, has good penetration and is suitable for filling as in the present invention.

[0033] Figure 3 is an explanatory cross-sectional view illustrating the reinforcement structure of a concrete tank 20 according to the concrete tank repair and reinforcement method 1 of the present invention. The structure consists of non-shrink mortar 50 injected between the inner wall N and the upper surface of the floor Y of the concrete tank 20 and a stainless steel plate 30. The concrete tank 20 and the battens 10 are fixed with anchor bolts, and the battens 10 and the stainless steel plate 30 are firmly fixed by butt welding or fillet welding using TIG welding.

[0034] Figure 4 is a process diagram illustrating each step of the concrete tank repair and reinforcement method 1 according to the present invention. Figure 4(a) shows the batten fixing step A, Figure 4(b) shows the stainless steel plate fixing step B and the stainless steel plate welding step C, and Figure 4(c) shows the filling step. In the batten fixing step A, stainless steel battens 10, which are framed to fix stainless steel plates 30 to the concrete tank 20, are fixed to the concrete tank 20 using anchor bolts. In the stainless steel plate fixing step B, the stainless steel plates 30 are positioned on the battens 10. In the stainless steel plate welding step C, multiple stainless steel plates 30 that are to be connected are welded together using a TIG welder or the like, either by butt welding or fillet welding, to prevent leaks. In the filling step E, non-shrink mortar 50 is filled into the space 40 that is created in the gap between the fixed stainless steel plates 30 and the inner wall N and the upper surface of the floor Y of the concrete tank 20.

[0035] The concrete tank repair and reinforcement method 1 according to the present invention is characterized by its ability to repair and reinforce with complete water leakage prevention by filling the space 40 between the stainless steel plate 30 and the upper surface of the inner wall N and floor Y with non-shrink mortar 50 instead of epoxy resin as in the conventional method, and by butt welding or fillet welding the stainless steel plate 30 that covers it. [Industrial applicability]

[0036] This invention addresses the fact that factories and facilities built during the period of rapid economic growth are now approximately 50 years old, and many water leaks are occurring in water treatment tanks and other facilities due to concrete deterioration, resulting in water continuously leaking out. Until now, specialized companies have been responsible for repair work, but the quality of their work is often insufficient, and the ongoing maintenance of concrete tanks is a source of concern for businesses. This invention is a technology that can solve such problems, and therefore is considered to have high industrial applicability. [Explanation of symbols]

[0037] 1. Methods for repairing and reinforcing concrete tanks 10 wooden beams 20 Concrete tank 30 stainless steel plates 40 space 50 Non-shrink mortar A Crosspiece fixing process B. Stainless steel plate fixing process C Stainless steel plate welding process D Vacuum Testing Process E Filling process F Pressure resistance test process N Interior wall Y floor H crack R Efflorescence K Concrete layer S Stainless Steel Layer M Non-shrink mortar layer

Claims

[Claim 1] A method for repairing and reinforcing a concrete tank, which involves installing a stainless steel inner wall inside, A process (A) involves fixing stainless steel battens (10) to a concrete tank (20), The stainless steel plate fixing step (B) involves fixing a plurality of stainless steel plates (30) to the battens (10) that were fixed in the batten fixing step (A), In the stainless steel plate fixing step (B), a stainless steel plate welding step (C) is performed in which the plurality of stainless steel plates (30) fixed to the battens (10) are butted together and welded; The vacuum testing process (D) involves performing a vacuum test to check for water leakage in the welded portion of the stainless steel plate welding process (C), A filling step (E) in which non-shrink mortar (50) is filled into the space (40) between the concrete tank (20) and the plurality of stainless steel plates (30) by the aforementioned wooden blocks (10), Pressure resistance test process (F): A pressure resistance test is conducted to confirm whether the product can withstand the pressure and load expected during actual use. A method for repairing and reinforcing a concrete tank, characterized by having (1).

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