Injection Crack Repair Method for Concrete Structures

Abstract

The present invention relates to a crack repair technology for concrete structures, and more specifically, to an injection crack repair method for concrete structures that simultaneously secures watertightness and structural stability by drilling a structural crack or leakage crack occurring in a concrete wall and injecting a foamed resin agent to fill and harden the inside of the crack.

Description

Technology Field

[0001] The present invention relates to a crack repair technology for concrete structures, and more specifically, to an injection crack repair method for concrete structures that simultaneously secures watertightness and structural stability by drilling a structural crack or leakage crack occurring in a concrete wall and injecting a foamed resin agent to fill and harden the inside of the crack. Background Technology

[0002] Cracks in concrete structures occur due to a combination of factors during long-term use, including drying shrinkage, heat of hydration, repeated expansion and contraction caused by changes in ambient temperature, ground settlement, vehicle vibrations, wind loads, carbonation, and rebar corrosion.

[0003] These cracks initially appear as fine hairline cracks, but as time passes, they gradually expand and extend, acting as a pathway for external moisture and air to penetrate into the structure.

[0004] Particularly in areas directly exposed to external water pressure or rainfall, such as exterior walls and basement perimeter walls, cracks are not merely an aesthetic issue but cause serious problems leading to indoor water leakage, reduced insulation performance, mold growth, peeling of finishing materials, accelerated rebar corrosion, and structural deterioration.

[0005] Conventionally, when the crack width is relatively small, methods of sealing the surface using crack seals, silicone-based coating materials, acrylic-based surface coating materials, etc., have been used.

[0006] However, this surface treatment method has a structural limitation in that it only blocks the externally exposed surface of the cracks and cannot penetrate deep into the pores of the concrete to form a watertight layer.

[0007] As a result, in environments where external water pressure is continuously applied, problems frequently occurred where water bypassed through internal pores or cracks expanded again due to repeated freezing and thawing, leading to re-leakage.

[0008] In addition, while epoxy or cement-based mortar filling methods have been applied in some cases, there is a problem in that the stiffness increases excessively after hardening, failing to absorb the micro-movements of the structure and making it prone to re-cracking.

[0009] Moreover, in a humid environment, there was a disadvantage in that long-term durability could not be ensured due to reduced adhesion and interfacial delamination.

[0010] Therefore, there is a need for a fundamental injection-based repair method that can directly penetrate into cracks and fill even micro-pores, while maintaining a certain level of elasticity after hardening to absorb structural behavior. Prior art literature

[0011] Registered Patent KR 10-2642003 (February 23, 2024) Rooftop waterproofing and crack repair reinforcement method using a composite sheet Registered Patent KR 10-2745959 (December 18, 2024) Exterior wall crack repair and reinforcement method of concrete structures using a composite sheet The problem to be solved

[0012] The present invention was created to satisfy the aforementioned needs and aims to provide an injection crack repair method for concrete structures that fundamentally prevents leakage by drilling at regular intervals along the cracks, pressurizing and injecting a foamed resin to completely fill the inside of the cracks, and simultaneously ensuring watertightness and elasticity after hardening. means of solving the problem

[0013] The present invention provides an injection crack repair method for a concrete structure, characterized by comprising, as a means to achieve the above-mentioned objective: a drilling step of drilling at regular intervals along the crack occurrence area; a foreign matter removal step of removing foreign matter inside the drilled holes using pneumatic pressure; a packer fixing step of inserting a packer into the drilled holes and fixing it using a T-box; an injection preparation step of connecting an injection injector to the packer; a resin injection step of injecting a foaming resin into the crack through the packer; a packer removal step of removing the packer after the foaming resin has cured; and a finishing step of finishing the crack area with a surface finishing material after removing the packer. Effects of the invention

[0014] According to the present invention, leakage can be fundamentally prevented by directly filling the inside of the crack, and the occurrence of re-cracking can be suppressed by maintaining a certain elasticity even after hardening, long-term adhesion can be maintained even in a wet environment, and the durability and maintenance efficiency of the structure can be significantly improved. Brief explanation of the drawing

[0015] FIG. 1 is a flowchart illustrating a crack repair method according to the present invention. FIGS. 2 to 4 are exemplary sample photographs showing the progress of a crack repair method according to the present invention, showing the crack area, the fixing of the packer, and the connection state of the injection device. Specific details for implementing the invention

[0016] Hereinafter, preferred embodiments according to the present invention will be described in more detail.

[0017] Prior to describing the present invention, the following specific structural or functional descriptions are provided merely for the purpose of illustrating embodiments according to the concept of the present invention. Embodiments according to the concept of the present invention may be implemented in various forms and should not be interpreted as being limited to the embodiments described herein.

[0018] In addition, since embodiments according to the concept of the present invention may be subject to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in this specification. However, this is not intended to limit the embodiments according to the concept of the present invention to specific disclosed forms, and it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention.

[0019] As shown in the examples of FIGS. 1 to 4, the injection crack repair method for concrete structures according to the present invention is applied to the cracks of concrete structures where leakage occurs.

[0020] The injection crack repair method for a concrete structure according to the present invention comprises: a drilling step of drilling at regular intervals along the crack occurrence area; a foreign matter removal step of removing foreign matter inside the drilled holes using pneumatic pressure; a packer fixing step of inserting a packer into the drilled holes and fixing it using a T-box; an injection preparation step of connecting an injection injector to the packer; a resin injection step of injecting a foaming resin into the crack through the packer; a packer removal step of removing the packer after the foaming resin has cured; and a finishing step of finishing the crack area with a surface finishing material after removing the packer.

[0021] To explain this more specifically step-by-step, it is as follows.

[0022] (1) Drilling stage

[0023] Drill holes at regular intervals (150–300 mm) along the surface of the cracked concrete wall.

[0024] At this time, the perforation is formed at an angle of inclination of 30 to 60 degrees toward the center of the crack so that the injected resin reaches deep inside the crack.

[0025] (2) Foreign substance removal step

[0026] After drilling, concrete dust, residue, fine aggregate, moisture, etc. remain inside the hole, and these foreign substances significantly reduce the adhesion with the resin.

[0027] Therefore, internal foreign matter is completely removed using the air pressure from the air compressor.

[0028] Afterwards, apply a pre-coating primer as needed.

[0029] The above primer is composed of 35 parts by weight of an amine curing agent, 5 parts by weight of γ-glycidoxypropyltrimethoxysilane, 4 parts by weight of polycarbodiimide, 3 parts by weight of zinc oxide, and 1.5 parts by weight of an antifoaming agent, based on 100 parts by weight of epoxy resin.

[0030] In this case, the epoxy resin acts as a base binder to ensure excellent adhesion to concrete and chemical resistance.

[0031] In addition, the amine curing agent reacts with the epoxy resin to form a three-dimensional cross-linked structure, thereby imparting high strength and water resistance. Preferably, isophorone diamine is used because it is CAS No. 2855-13-2, which has low viscosity, excellent water resistance, resistance to yellowing, excellent long-term durability, and excellent adhesion to the concrete interface.

[0032] In addition, γ-glycidoxypropyltrimethoxysilane acts as a silane coupling agent to chemically strengthen the interfacial bonding between inorganic concrete and organic resin, thereby increasing adhesion.

[0033] In addition, polycarbodiimide improves moisture stability and increases resistance to hydrolysis, allowing it to maintain adhesion even in wet environments.

[0034] In addition, zinc oxide imparts antibacterial and weather resistance and improves long-term durability.

[0035] Furthermore, to prevent interfacial defects by suppressing bubbles generated during application, polydimethylsiloxane is preferably used. This is because, as a representative silicone-based defoaming agent, it has a powerful bubble-removing effect even in minute quantities, is particularly stable on resin-based coatings, and, above all, is highly effective in removing bubbles at concrete interfaces.

[0036] Additionally, 5 parts by weight of tetrasodium EDTA and 5 parts by weight of ammonium persulfate may be added to 100 parts by weight of the above epoxy resin. In this case, tetrasodium EDTA is added to chelate metal ions and stabilize unstable metallic components such as iron ions and calcium ions remaining on the concrete surface, thereby removing future corrosion-promoting factors; and ammonium persulfate can be used to oxidize and decompose organic contaminants and microbial residues by acting as a strong oxidizing agent.

[0037] (3) Packer fixing step

[0038] Insert an inflatable or mechanical packer into the drilled hole and securely fasten it from the outside using a T-box.

[0039] (4) Resin injection step

[0040] Connect the injection injector to the packer and inject the foaming resin under pressure.

[0041] The above foaming resin is composed of 85 parts by weight of diphenylmethane diisocyanate (MDI), 20 parts by weight of polypropylene glycol, 3.5 parts by weight of triethylenediamine, 2.5 parts by weight of silicone-based surfactant, 4 parts by weight of moisture-reactive foaming promoter, and 5 parts by weight of nanosilica, based on 100 parts by weight of polyol.

[0042] A foamed resin made of such a composition completely fills the internal voids of the cracks and forms an elastic watertight layer after curing.

[0043] In this case, the polyol serves as the main component forming the basic framework, imparting elasticity and elongation. Preferably, polypropylene glycol is used, as it is suitable for injection repair due to its low viscosity, excellent water resistance, and contribution to increased elasticity.

[0044] In addition, diphenylmethane diisocyanate (MDI) reacts with polyols to form urethane bonds, ensuring high strength and water resistance.

[0045] In addition, polypropylene glycol forms soft segments to increase flexibility and absorb structural behavior.

[0046] In addition, triethylenediamine acts as a catalyst to control the foaming reaction and curing speed.

[0047] In addition, silicone-based surfactants induce the formation of a uniform foam structure, thereby ensuring uniform mechanical strength. In this case, a dimethylsiloxane-ethylene oxide copolymer can be used.

[0048] In addition, the moisture-reactive foaming agent reacts with moisture inside the crack to generate CO₂, thereby inducing expansion force. Preferably, dibutyltin dilaurate is used, which is CAS No. 77-58-7 and has the advantage of being a urethane reaction-promoting catalyst and capable of controlling the foaming reaction rate.

[0049] In addition, nanosilica provides a filling effect as a fine particle and improves compressive strength and wear resistance.

[0050] In addition, 4.5 parts by weight of zirconium alkoxide, 5 parts by weight of sodium dodecylbenzenesulfonate, and 5 parts by weight of sodium gluconate may be further added to 100 parts by weight of polyol.

[0051] In this case, zirconium alkoxide is added to maximize interfacial adhesion by promoting the formation of an inorganic network and inducing chemical bonding with hydroxyl groups within the concrete.

[0052] In addition, sodium dodecylbenzenesulfonate is added to perform a surfactant function, lower surface tension, and induce penetration into the interior of microcracks.

[0053] In addition, sodium gluconate is added to suppress sudden changes in pH by performing a buffering function.

[0054] (5) Packer removal step

[0055] Remove the packer after it has fully cured.

[0056] (6) Final stage

[0057] After removing the packer, the exposed perforations and cracks are finished with a surface finish.

[0058] The above surface finishing material is made by mixing 25 parts by weight of metakaolin, 20 parts by weight of re-emulsifiable polymer powder, 2 parts by weight of polypropylene staple fiber, 4 parts by weight of shrinkage reducing agent, 10 parts by weight of silica fume, and 6 parts by weight of waterproofing additive with respect to 100 parts by weight of hydraulic cement.

[0059] At this time, hydraulic cement forms the basic structural strength.

[0060] In addition, metakaolin improves density and increases durability through the pozzolanic reaction.

[0061] In addition, the re-emulsifiable polymer powder improves adhesion and water resistance and prevents interfacial delamination. Preferably, an ethylene-vinyl acetate copolymer is used.

[0062] In addition, polypropylene staple fibers play a role in controlling microcracks and reinforcing tensile strength.

[0063] In addition, shrinkage reducing agents inhibit drying shrinkage and prevent re-cracking. Preferably, 1,2-propanediol is used.

[0064] Furthermore, silica fume fills the micropores, increasing water tightness and strength.

[0065] In addition, the waterproofing additive inhibits capillary absorption and ensures long-term watertightness. Preferably, calcium stearate is used.

[0066] Surface finishing materials with such a composition ensure both structural stability and aesthetics.

[0067] The following examples are described.

[0068] An example of the invention was prepared in which a foamed resin composed of the above-described composition was injected into an artificially formed crack (width 0.5 mm, length 200 mm) in a concrete test specimen of 300 mm × 300 mm × 100 mm.

[0069] At this time, for comparison, a comparative example was also prepared in which only general epoxy resin was injected without foaming.

[0070] After curing was complete, a water pressure of 0.3 MPa was applied to the back of the test specimen for 48 hours.

[0071] As a result of the test, leakage occurred in the comparative example after 30 hours, while leakage did not occur in the inventive example even after 48 hours.

[0072] In addition, durability against repetitive loading after injection was also evaluated.

[0073] At this time, the test conditions were 3-point bending repeated loading, load range: 0~60% breaking load, number of repetitions: 10,000 times, and the test results showed that in the comparative example (epoxy non-foaming injection): microcracks recurred after 3,000 times, while in the inventive example, there was no crack recurrence up to 10,000 times.

[0074] This is believed to be because the elasticity and elongation characteristics of the foamed resin absorb the micro-movements of the structure.

Claims

Claim 1 A drilling step of drilling at regular intervals along the crack area; a foreign matter removal step of removing foreign matter inside the drilled holes using pneumatic pressure; a packer fixing step of inserting a packer into the drilled holes and fixing it using a T-box; an injection preparation step of connecting an injection injector to the packer; a resin injection step of injecting a foaming resin into the crack through the packer; and a packer removal step of removing the packer after the foaming resin has cured. In an injection crack repair method for a concrete structure comprising: a finishing step of finishing the cracked area with a surface finishing material after removing a packer; wherein the pre-coating primer applied to the inside of the drilled hole and the crack surface after the foreign substance removal step is composed by mixing 35 parts by weight of an amine curing agent, 5 parts by weight of γ-glycidoxypropyltrimethoxysilane, 4 parts by weight of polycarbodiimide, 3 parts by weight of zinc oxide, and 1.5 parts by weight of an antifoaming agent with respect to 100 parts by weight of epoxy resin, wherein 5 parts by weight of tetrasodium EDTA and 5 parts by weight of ammonium persulfate are further added with respect to 100 parts by weight of the epoxy resin; and the foaming resin used in the resin injection step is composed of 85 parts by weight of diphenylmethane diisocyanate (MDI), 20 parts by weight of polypropylene glycol, 3.5 parts by weight of triethylenediamine, 2.5 parts by weight of a silicone-based surfactant, and a moisture-reactive type with respect to 100 parts by weight of polyol. An injection crack repair method for a concrete structure, characterized by being composed by mixing 4 parts by weight of a foaming agent and 5 parts by weight of nanosilica, wherein 4.5 parts by weight of zirconium alkoxide, 5 parts by weight of sodium dodecylbenzenesulfonate, and 5 parts by weight of sodium gluconate are further added to 100 parts by weight of the polyol; and the surface finishing material used in the finishing step is composed by mixing 25 parts by weight of metakaolin, 20 parts by weight of ethylene-vinyl acetate copolymer, 2 parts by weight of polypropylene staple fiber, 4 parts by weight of 1,2-propanediol, 10 parts by weight of silica fume, and 6 parts by weight of calcium stearate to 100 parts by weight of hydraulic cement. Claim 2 delete Claim 3 delete

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