Interfacially Integrated Concrete Section Repair Method

Abstract

The present invention relates to a cross-section repair method for long-term repair of damaged and deteriorated parts of concrete structures, and more specifically, to a concrete cross-section repair method having an interface-integrated structure that improves adhesive performance, environmental resistance, and long-term durability by forming a structure in which the interlayer interfaces are integrated during the process of forming a plurality of repair layers. That is, the present invention relates to a cross-section repair method for repairing damaged parts of concrete structures, comprising: a primer layer applied to the surface of existing concrete; a filling layer formed on top of the primer layer to fill the damaged cross-section; and a film layer formed on top of the filling layer to protect the repair surface; wherein the primer layer, the filling layer, and the film layer comprise an acrylic copolymer binder of the same series, and at least one of the primer layer, the filling layer, and the film layer comprises a reactive crosslinking agent that forms interlayer crosslinking through a chemical reaction upon mutual contact, thereby forming a chemically integrated interlayer crosslinking structure at the interface of each layer.

Description

Technology Field

[0001] The present invention relates to a cross-section repair method for long-term repair of damaged and deteriorated parts of concrete structures, and more specifically, to a concrete cross-section repair method having an interface-integrated structure that improves adhesion performance, environmental resistance, and long-term durability by forming a structure in which the interlayer interfaces are integrated during the process of forming a plurality of repair layers. Background Technology

[0003] In general, concrete structures are subject to damage such as cracking, spalling, and delamination over long periods due to various environmental factors including loads, temperature changes, salt damage, freeze-thaw cycles, and carbonation. Such damage leads to a deterioration in structural performance and weakened durability, making the periodic application of section repair methods essential.

[0005] Conventional concrete section repair technology has generally involved removing the damaged area, applying cement mortar or polymer mortar as a filler, and, if necessary, separately forming a primer layer to improve adhesion or a coating layer for surface protection. However, this multi-layer repair method has structural limitations, such as insufficient chemical affinity between layers, because the binder compositions of the materials applied to each layer differ.

[0007] In particular, the bonding between the primer layer, filler layer, and surface film layer often relies primarily on physical adhesion or surface roughness; consequently, interfacial stresses become concentrated due to changes in temperature and humidity, drying shrinkage, and repeated loading, leading to frequent interfacial delamination, the occurrence of microcracks, and the recurrence of damage. Although such interlayer delamination may not manifest as an external issue during the initial stages of construction, it has been identified as a major cause of rapid adhesion degradation and durability deterioration during long-term use.

[0009] Conventional technology has focused primarily on improving the mechanical performance of individual layers, such as by applying high-strength mortar, fiber reinforcement, or increasing surface roughness, in order to address these problems. However, this approach has not fundamentally resolved the structural characteristics of each layer existing independently, and has limitations in resolving the lack of bonding strength caused by chemical discontinuities occurring at the interlayer interface.

[0010] In other words, existing cross-section repair methods have limitations in that they remain as simple stacked structures rather than forming the entire multi-layered structure into a single integrated body. Prior art literature

[0012] Registered Patent No. 10-2224215 (Mortar composition having crack resistance and shrinkage resistance and method for repairing concrete structure sections using the same) Registered Patent No. 10-2337868 (Surface treatment repair method for restoring concrete structure sections combined with neutralization and salt damage prevention functions) The problem to be solved

[0013] The present invention was devised to solve the above-mentioned problems, and aims to provide a concrete section repair technology that combines construction efficiency and economic feasibility by chemically integrating the primer layer, the filler layer, and the surface film layer at the interface to fundamentally resolve the problems of interlayer delamination, reduced adhesion, and re-cracking that repeatedly occurred in existing concrete section repair methods, while ensuring flexible process combinations and stable construction quality even in various field environments including wet conditions, and reducing long-term maintenance costs through process shortening and repair cycle reduction. means of solving the problem

[0015] The present invention relates to a cross-sectional repair method for repairing a damaged area of ​​a concrete structure, comprising: a primer layer applied to the surface of the existing concrete; a mortar filling layer formed on top of the primer layer to fill the damaged cross-section; and a film layer formed on top of the filling layer to protect the repair surface; wherein the primer layer, the filling layer, and the film layer comprise an acrylic copolymer binder of the same series, and the primer layer and the film layer, excluding the filling layer, comprise a reactive crosslinking agent that forms interfacial crosslinking through a chemical reaction upon mutual contact, thereby forming a chemically integrated interlayer crosslinking structure at the interface of each layer.

[0017] In addition, the acrylic copolymer binder is characterized by being composed of one or more of styrene-acrylate, methyl methacrylate-acrylate, ethyl acrylate-butyl acrylate, or acrylic acid-acrylate copolymers.

[0019] In addition, the reactive crosslinking agent is characterized by reacting with at least one of a carboxyl group (COOH), a hydroxyl group (OH), an amide group (-C(=O)-NH-), or a silane functional group (-Si(OR)₃ or -Si-OH) included in the acrylic copolymer binder to form an interfacial crosslink.

[0021] In addition, the reactive crosslinking agent is characterized by being composed of one or more of amine-silane, phosphate, and zirconium compounds. Effects of the invention

[0023] The present invention is a multilayer homogeneous concrete section repair technology that applies a reactive crosslinking agent and an acrylic copolymer binder in common, and provides the following technical and economic effects.

[0025] First, there is an effect of improving adhesive performance due to interlayer chemical integration.

[0026] The present invention applies an acrylic copolymer binder and a reactive crosslinking agent of the same series to the primer layer, filler layer, and film layer in common, thereby forming chemical bonds between functional groups such as carboxyl groups and hydroxyl groups and the crosslinking agent at the interfaces of each layer. Accordingly, the bonding between the repair layers goes beyond simple physical adhesion to form a continuous integrated structure based on chemical bonding, and the entire repair layer is integrated into a single network structure. As a result, interfacial adhesion performance is improved, and interlayer delamination and re-cracking phenomena that are prone to occur during long-term use are effectively suppressed, thereby increasing the stability and reliability of the repair layer.

[0028] Second, water resistance, chemical resistance, and structural durability are improved.

[0029] The reactive crosslinking agent applied in this invention reacts with the functional groups of the acrylic copolymer binder to form a dense crosslinking network, thereby effectively suppressing the penetration of moisture and chloride ions into the repair layer. Furthermore, since each repair layer is composed based on an elastic acrylic copolymer of the same series, differences in the coefficient of thermal expansion and deformation behavior between layers are minimized, thereby alleviating stress concentration caused by temperature changes or repeated loading. Consequently, the water resistance and chemical resistance of the repair layer are improved, while long-term structural durability and service life are increased.

[0031] Third, it offers excellent construction efficiency and application flexibility.

[0032] The cross-section repair method of the present invention basically applies a multilayer structure consisting of a primer layer, a filler layer, and a coating layer, but allows for combination construction in which some layers are selectively applied depending on the depth of damage, environmental conditions, or construction conditions. Even in such cases, the same binder series and cross-linking reaction mechanism are maintained, so the construction process is simplified while the interfacial integration effect is stably secured. Through this, it is possible to flexibly respond to various site conditions, and work efficiency and the uniformity of construction quality are improved.

[0034] Fourth, economic efficiency and maintenance efficiency are improved.

[0035] The chemically integrated structure of the present invention simultaneously ensures initial adhesive performance and long-term durability, thereby reducing premature deterioration after repair or the occurrence of repeated repairs. Consequently, the repair cycle is extended, and long-term maintenance costs can be expected to be reduced. Furthermore, overall economic efficiency is enhanced by the added benefit of reduced indirect costs resulting from the simplification and shortening of the construction process.

[0037] Accordingly, the present invention provides a concrete section repair technology capable of overcoming the limitations of existing physical adhesion-centered section repair methods and simultaneously achieving high adhesion, high durability, and excellent economic efficiency through an interlayer chemical integration structure using a reactive crosslinking agent and an acrylic copolymer binder. Therefore, the present invention can contribute to maintaining the long-term performance of various concrete-based social infrastructure facilities, such as roads, bridges, and tunnels, and reducing maintenance costs. Brief explanation of the drawing

[0039] FIG. 1 is a cross-sectional schematic diagram of a concrete section repair method having an interface integrated structure according to the present invention. FIG. 2 is an exemplary diagram showing the interlayer chemical bonding of a concrete section repair method having an interface-integrated structure according to the present invention. FIG. 3 is a drawing showing the construction procedure of a concrete cross-section repair method having an interface integrated structure according to the present invention. Specific details for implementing the invention

[0040] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Furthermore, in describing the present invention, detailed descriptions of related known functions or configurations are omitted if it is determined that such detailed descriptions may unnecessarily obscure the essence of the present invention.

[0042] The concrete section repair method having an interface-integrated structure according to the present invention is a technology for a section repair method for repairing damaged areas of a concrete structure. More specifically, as illustrated in FIG. 1, the section repair method for repairing damaged areas of a concrete structure comprises: a primer layer applied to the surface of the existing concrete; a mortar filling layer formed on top of the primer layer to fill the damaged section; and a film layer formed on top of the filling layer to protect the repair surface; wherein the primer layer, the filling layer, and the film layer comprise an acrylic copolymer binder of the same series, and the primer layer and the film layer, excluding the filling layer, comprise a reactive crosslinking agent that forms an interfacial crosslinking bond through a chemical reaction upon mutual contact, thereby forming a chemically integrated interlayer crosslinking structure at the interface of each layer.

[0044] The concrete section repair method having an interface-integrated structure according to the present invention is a method designed to repair damaged or deteriorated areas of a concrete structure such that a plurality of repair layers, comprising a primer layer, a filling layer, and a coating layer, are not separated from each other and form an integrated structure at the interface.

[0046] In the present invention, a primer layer is first applied to the existing concrete surface to form an adhesion base with the surface to be repaired, a filling layer is formed on top of the primer layer to restore the damaged concrete cross-section, and subsequently, a film layer is formed on top of the filling layer to protect the repaired surface from the external environment. Although the structure in which the primer layer, filling layer, and film layer are formed sequentially is similar to conventional cross-section repair methods, the present invention has fundamental differences in the composition and bonding method of each layer.

[0048] That is, according to the present invention, the primer layer, the filler layer, and the film layer are all configured to include an acrylic copolymer binder of the same series, and the primer layer and the film layer also include a reactive crosslinking agent capable of inducing a chemical reaction upon mutual contact. As a result, instead of simply stacking each repair layer, chemical crosslinking is formed at the interlayer interface to form an integrated structure that is interconnected.

[0050] The above acrylic copolymer binder may be composed of one or more of styrene-acrylate, methyl methacrylate-acrylate, ethyl acrylate-butyl acrylate, or acrylic acid-acrylate copolymers, thereby allowing adhesion, elasticity, water resistance, and environmental resistance to be adjusted to suit the usage conditions of the structure to be repaired.

[0052] The above acrylic copolymer binder includes a carboxyl group (COOH), a hydroxyl group (OH), an amide group (-C(=O)-NH-), or a silane functional group (-Si(OR)₃ or -Si-OH) contained in the acrylic copolymer binder within its molecular structure, thereby enabling chemical interaction with the reactive crosslinking agent used in the present invention. Accordingly, a crosslinking reaction is induced at the interface where each repair layer contacts, forming a chemically connected bond structure that does not rely on simple physical attachment.

[0054] The reactive crosslinking agent of the present invention is included in the primer layer and the film layer and performs a key function of realizing an interlayer integrated structure by forming chemical crosslinking bonds at the interface between the repair layers. The reactive crosslinking agent reacts with at least one of a carboxyl group (COOH), a hydroxyl group (OH), an amide group (-C(=O)-NH-), or a silane functional group (-Si(OR)₃ or -Si-OH) included in the acrylic copolymer binder to form interfacial crosslinking bonds.

[0056] Meanwhile, the filler layer is composed of a cement-based polymer mortar, and since the inclusion of a reactive crosslinking agent in an amount exceeding a certain limit may inhibit the hydration reaction of the cement and potentially reduce adhesion and mechanical strength, it is preferably configured not to include the said reactive crosslinking agent.

[0058] According to this composition, the reactive crosslinking agent included in the primer layer reacts at the interface with the functional groups of the acrylic copolymer binder included in the filler layer and the hydroxyl groups on the surface of the cement hydrate to form a chemical crosslink between the primer layer and the filler layer, and the reactive crosslinking agent included in the coating layer applied on top of the filler layer reacts with the surface of the filler layer to strengthen the interfacial bond between the filler layer and the coating layer.

[0060] Accordingly, even if a reactive crosslinking agent is not included within the filled layer, chemical crosslinking is selectively formed at each interface between the primer layer and the filled layer and between the filled layer and the film layer, so that the entire repair layer forms a continuous, integrated structure centered on the interfaces.

[0062] More specifically, the reactive crosslinking agent reacts with carboxyl groups (-COOH) and ester groups (-COOR) contained in the acrylic binder, and with hydroxyl groups (-OH) present on the surface of each retention layer, to form chemical bonds such as siloxane bonds (Si-O-Si), silane-organic bonds (Si-OC), or amide bonds (-CO-NH-).

[0063] These cross-linking reactions proceed not only within each maintenance layer (ABC) but are also simultaneously induced at the interface where adjacent maintenance layers contact, forming a continuous chemical bond network across the interface.

[0065] Accordingly, each repair layer is not merely a structure laminated by physical adhesion, but forms an integrated structure interconnected based on various chemical bonds. As a result, stress transfer is uniform at the interfaces between the repair layers, and the occurrence of delamination or cracking is effectively suppressed even during long-term use. This chemical integration mechanism provides a key technical basis for simultaneously securing interfacial bonding stability and long-term durability in the concrete section repair method according to the present invention.

[0067] The reactive crosslinking agent applied in the present invention is a functional compound for forming chemical crosslinking bonds at the interface between repair layers, and may consist of one or more of amine-silane compounds, phosphate compounds, and zirconium compounds. Such a reactive crosslinking agent may be used alone, or multiple types may be mixed and applied depending on the conditions of the structure to be repaired and the construction environment.

[0069] Below, the characteristics of the above-mentioned reactive crosslinking agent will be explained.

[0071] First, amine-silane crosslinking agents improve adhesion between repair layers by forming chemical bonds at the interface through condensation reactions with hydroxyl groups (-OH) or carboxyl groups (-COOH) contained in acrylic binders, and at the same time, they improve the water resistance of the repair structure by forming hydrogen bonds or ionic bonds with carbonyl groups (C=O) within the binder molecules.

[0073] In addition, the phosphate crosslinking agent functions to improve water resistance and heat resistance by forming a bonding network between organic and inorganic components through an esterification reaction with hydroxyl groups (-OH) or carboxyl groups (-COOH) contained in the acrylic binder, thereby increasing the crosslinking density at the interface and densely configuring the bonding structure between the water retention layers.

[0075] In addition, the zirconium-based crosslinking agent forms strong coordination bonds with carbonyl groups (C=O) and hydroxyl groups (-OH) contained in the acrylic binder, thereby strengthening the bonding stability between the repair layers and improving resistance to the external environment, so that adhesive performance and chemical resistance are stably maintained even during long-term use.

[0077] The above crosslinking agent can be applied in an amount of 0.2 to 2.0% based on the solid content of the binder in each layer, and viscosity stability and reaction efficiency are optimized when controlled to 0.3 to 1.2% based on the total system.

[0079] The content of each layer of the present invention is described as follows.

[0081] First, the primer layer comprises 70 to 90 parts by weight of an acrylic copolymer binder having a solid content of 40 to 55%, and is characterized by comprising 0.5 to 5 parts by weight of a reactive crosslinking agent relative to the solid content of the binder, 1 to 10 parts by weight of an alcohol-based solvent relative to the total composition, 0.1 to 2 parts by weight of a thickener, 0.05 to 1 part by weight of a pH adjuster, and 0.05 to 1 part by weight of a degassing agent and a dispersing agent, respectively.

[0083] The above-mentioned filling layer comprises a mortar composition including cement and silica sand, wherein the mortar comprises 83 to 87 parts by weight based on the total composition, an acrylic copolymer binder comprises 2 to 3 parts by weight based on solid content, and water comprises 10 to 15 parts by weight.

[0085] The film layer comprises 70 to 90 parts by weight of an acrylic copolymer binder having a solid content of 40 to 55 parts by weight, about 0.5 to 1.5 parts by weight of a reactive crosslinking agent relative to the solid content of the binder, and about 1 to 5 parts by weight of silica microparticles relative to the total composition, wherein the silica microparticles have an average particle size of about 0.2 to 1.0 μm, and comprises about 0.1 to 1 part by weight of an antifoaming agent and about 0.05 to 0.5 parts by weight of a pH adjuster relative to the total composition.

[0087] In addition, the concrete section repair method having an interface-integrated structure according to the present invention is performed in a wet state, and specifically, as shown in FIG. 3, comprises a surface preparation step of removing fine dust and impurities by cutting and cleaning the damaged area of ​​the deteriorated concrete, a primer application step of inducing chemical activation of the surface of the base layer by uniformly applying a primer to the concrete base layer, a wet filling layer construction step of laying polymer mortar on the primer layer in a wet state in which a certain amount of moisture remains, a first curing step of securing basic structural strength by proceeding with the hardening of the filling layer, a film layer application step of uniformly applying an elastic film that blocks moisture and chlorides on the upper part of the filling layer, and a second curing step in which final hardening is achieved by completing the cross-linking reaction between all layers.

[0089] According to this process configuration, the concrete section repair method of the present invention is configured so that each step is interconnected to form an interface-integrated structure.

[0090] Specifically, in the surface preparation stage, damaged areas of deteriorated concrete are cut and cleaned to remove fine dust and impurities, thereby securing a base layer condition that allows chemical reactions in subsequent processes to proceed smoothly.

[0092] Subsequently, in the primer application step, a primer containing a reactive crosslinking agent is uniformly applied to the surface of the concrete base layer to allow the primer to penetrate into the micropores of the concrete while simultaneously chemically activating the surface of the base layer.

[0094] Next, in the wet-on-wet layer construction stage, a filling layer made of cement mortar is continuously constructed under conditions where the surface moisture content is maintained in the range of 4 to 6%, before the primer layer is completely dried, thereby ensuring that the primer layer and the filling layer come into contact without being physically separated. In this process, functional groups such as carboxyl groups (-COOH) and hydroxyl groups (-OH) of the acrylic copolymer binders contained in the primer layer and the filling layer, respectively, react with each other at the interface through the mediating action of a reactive crosslinking agent, thereby forming an interfacial crosslinked layer.

[0096] Next, in the first curing stage, the filling layer is hardened to secure basic structural strength, and at the same time, the interfacial cross-linking reaction between the primer layer and the filling layer is stably carried out.

[0098] In the next step of applying the film layer, an elastic film layer is applied to the top of the filled layer where the first curing has been performed to block the penetration of moisture and chlorides, thereby inducing chemical bonding between the filled layer and the film layer through a binder and a crosslinking agent of the same series.

[0100] Finally, in the second curing stage, the cross-linking reaction across the primer layer, filler layer, and coating layer is completed to achieve final hardening, thereby completing a concrete section repair layer having a chemically continuous interface integrated structure rather than a structure in which each layer is individually stacked.

[0102] More specifically, in the repair method of the present invention, the primer layer (A) is applied to the surface of the concrete base layer and penetrates into the micropores, and the reactive crosslinking agent forms a chemical anchor layer mixed with Si-O-Ca / Zr-OP / POC on the concrete surface under an appropriate moist environment.

[0103] Subsequently, the mortar filling layer (B) is applied under wet-on-wet conditions before the primer layer is completely dried, that is, when the surface moisture content is maintained in the range of 4 to 6%, and within a reactive activation window of 10 to 60 minutes in which the crosslinking agent remains active. Under these conditions, the crosslinking agent of layer A and the functional groups (-COOH, -OH, C=O, etc.) of the latex of layer B react directly to form a chemical bond layer based on covalent bonding at the interface, rather than simple mechanical adhesion.

[0104] The filling layer secures structural strength through a primary curing stage after construction, and then a surface coating layer (C) is applied.

[0105] The surface film layer (C) is applied when the surface residual moisture content of the packing layer (B) is 6% or less, and the crosslinking agent in the film layer (C) combines with the reaction residues of the packing layer (B) to form a bonding network, thereby completing a continuous chemical network with increased hardness, water resistance, and alkali resistance.

[0106] After application, the crosslinking reaction is stably completed through a secondary curing stage of 24 to 48 hours under conditions of approximately 25 °C and 60% relative humidity.

[0108] <Formulation of each composition>

[0109] 1. Formation of Layer A (Primer Layer)

[0110] 100 parts by weight (45% solid content) of a styrene-acrylic water-dispersible binder was used, and 2 parts by weight of an amine-silane, phosphate, and zirconium crosslinking agent were added relative to the solid content of the binder. In addition, 5 parts by weight of ethanol or IPA, 0.5 parts by weight of a HASE-based thickener, 0.2 parts by weight of a pH adjuster, and 0.3 parts by weight each of a degassing agent and a dispersing agent were mixed together. Among the crosslinking agents, 0.2 to 0.5 parts by weight of the phosphate crosslinking agent is most appropriate, as if it is less than 0.2 parts by weight, the reactivity with the -OH (hydroxyl group) of the acrylic binder decreases, thereby reducing the effect of increasing crosslinking density through a uniform esterification reaction, and if it exceeds 0.5 parts by weight, it may affect setting at the interface with cement.

[0111] This primer layer is designed to penetrate the surface of the concrete base layer to secure chemical adhesion, and through the application of a low amount of crosslinking agent, to form a layer with excellent water and chemical resistance throughout the concrete structure, and to increase viscosity stability and reaction diffusion.

[0113] 2. Composition of Layer B (Cement Filled Layer)

[0114] Mortar (cement + silica sand mixture) was used in a ratio of 85.7 parts by weight, styrene-acrylic latex (based on solid content) in a ratio of 2.9 parts by weight, and water in a ratio of 11.1 parts by weight, and no crosslinking agent was included.

[0115] In addition, the filler layer must be applied after the primer layer has sufficiently dried. At this time, it should be applied when there are no visible water droplets or lubricating layers on the surface and the surface moisture content is 4–6%. If the moisture content is less than 4%, active crosslinking reactions do not occur at the interface, which may lead to reduced adhesion; if the moisture content exceeds 6%, abnormal setting may occur due to the phosphate-based crosslinking agent contained in the primer. This filler layer is applied in such a way that it induces a reaction with the residual crosslinking agent in the primer layer without interfering with the cement hydration reaction and the formation of the upper film layer.

[0116] As a result, Layer B was adjusted to form an interlayer integrated structure through chemical bonding with Layer A, while simultaneously ensuring crack resistance and water resistance.

[0118] 3. Composition of Layer C (Surface Film Layer)

[0119] 100 parts by weight of a styrene-acrylic binder was used, and 0.8 parts by weight of an amine-silane, phosphate, and zirconium crosslinking agent were added relative to the solid content of the binder. To this, 3 parts by weight of silica fine particles (average particle size 0.5 μm), 0.3 parts by weight of an antifoaming agent, and 0.2 parts by weight of a pH adjuster were combined.

[0120] This film layer was designed with a relatively high crosslinking agent content to strengthen the formation of a chemically anchored layer with layer B, and it served to improve long-term environmental resistance (water resistance, salt resistance, weather resistance) by blocking the penetration of external moisture and chloride ions.

[0122] <Evaluation of Physical Properties and Performance>

[0123] This example was performed to evaluate durability performance, such as interlayer adhesion strength, salt resistance, and water absorption rate, on specimens prepared according to the composition of Example 1. All tests were repeated under the same conditions based on KS standards.

[0125] 1. Adhesion Strength Test (KS F 2762)

[0126] After attaching ABC 3-layer structure specimens to concrete substrates in a surface-dry state and a surface-wet state, respectively, the tensile bond strength was measured at 7 and 28 days of curing. As a result, the composition of the present invention showed a bond strength of 1.3 to 1.5 MPa at 28 days in a surface-dry state and 1.9 to 2.1 MPa at 28 days in a surface-wet state, which was an improvement of about 35% compared to general acrylic repair materials (about 1.4 MPa).

[0127] This improvement was analyzed to be due to the effect of the interfacial crosslinked layer formed at the interface between the primer layer and the filler layer.

[0129] 2. Salt resistance test (KS F 2711)

[0130] The resistance to chloride ion penetration was evaluated on specimens cured for 28 days. The composition of the present invention reduced the amount of chloride ion diffusion by more than 35% compared to conventional non-crosslinked acrylic films, and it was confirmed that this was because the crosslinking network of the surface film layer (layer C) effectively blocked the movement of moisture and chloride ions.

[0132] 3. Absorption rate test (KS F 2459)

[0133] 50×50×50 mm specimens were evaluated based on the difference in mass before and after drying following 24 hours of immersion. The specimen of the present invention was measured to have an absorption rate of 4.6%, which is a decrease of approximately 33% compared to conventional polymer mortar (6.9%).

[0134] This was interpreted as being due to the influence of the continuous waterproof structural layer formed by the styrene-acrylic binder applied to both layers A and C.

[0136] 4. Analysis and Discussion

[0137] The three-stage homogeneous system (ABC) of the present invention is

[0138] - Adhesion strength improved by approximately 35%,

[0139] - Chloride ion penetration reduction of 35% or more,

[0140] - It showed a performance improvement effect of reducing the absorption rate by more than 30%.

[0141] Therefore, it was confirmed that a styrene-acrylic homogeneous concrete section repair composition containing a reactive crosslinking agent exhibits significantly superior performance in chemical bonding strength, environmental resistance, and long-term stability compared to existing physical adhesive-centered repair materials.

[0143] Specialized construction method considering the chemical properties of the composition

[0145] 1. Chemical reaction-induced 'wet-on-wet' construction method

[0146] The core of the present invention lies in a wet-on-wet construction method that directly induces interlayer chemical bonding by continuously constructing an upper layer (B) under conditions where a reactive crosslinking agent included in a primer layer (A) remains in an active state.

[0147] This method involves applying the upper layer before the primer layer is completely dry, that is, within the reactive wet range where the surface moisture content is maintained in the 4-6% range, so that the functional groups (-COOH, -OH, -NH-, etc.) in the binder of layers A and B form a covalent-based interfacial crosslinked layer through the mediation of a crosslinking agent.

[0148] The optimal construction conditions at this time are as follows.

[0149] - Construction temperature: 20 ± 5 °C

[0150] - Relative humidity: 50 ± 10 %

[0151] - Wet application time (after primer application): Within 10 to 60 minutes

[0152] Under these conditions, the reaction activity of the crosslinking agent is maximized, so the interface is formed as a chemical bonding layer rather than a simple physical bond, and the entire repair layer exhibits integrated structural characteristics. Therefore, unlike the conventional dry-after-adhesion method, the wet construction procedure of the present invention is a reactive process that initiates and promotes chemical bonding during the construction process itself, thereby simultaneously realizing improved interlayer adhesion, crack suppression, and long-term durability.

[0154] 2. Construction of the Filled Layer (Layer B) - Chemical Bonding-Based Structure Formation Process

[0155] The construction of the filling layer of the present invention was not merely a simple mechanical filling, but a key step in which a chemical reaction with the reactive crosslinking agent of the primer layer (Layer A) was induced to form an integrated structure at the interface. By filling with a polymer mortar containing styrene-acrylic latex, the crosslinking agent remaining in Layer A directly reacted with the carboxyl and hydroxyl groups within the mortar to form an interfacial crosslinked layer. This reaction proceeded simultaneously with the filling, and the interlayer adhesion was strengthened beyond simple physical attachment to a covalent bond-based bonding layer. Consequently, Layer B acted as a structural core layer chemically connecting the lower primer layer and the upper surface film layer (Layer C), and functioned as the central technology of the present invention to improve the stress dispersion and crack resistance of the entire repair body.

[0157] 3. Application of Surface Coating Layer (Layer C) - Construction Method Focused on Key Conditions for Improved Environmental Resistance

[0158] The application of the surface film layer is not merely the formation of a protective film, but the final process that secures long-term environmental resistance by completing the chemical bonding between Layer B and Layer C. Application was performed when the initial curing of Layer B was completed, and the most stable cross-linking reaction was induced when the residual moisture content on the surface was 6% or less. The application temperature was maintained in the range of 20–30 °C, a condition designed to ensure a balance between the reactivity of the cross-linking agent and the film formation speed. Since direct sunlight or strong winds could cause premature drying and reduce the efficiency of chemical bonding, protection was provided by setting a 'reactive curing window' for 4–6 hours immediately after application.

[0159] The film composition was composed mainly of a styrene-acrylic binder and was applied with a uniform thickness (0.3–0.5 mm) using an airless spray or roller. After application, the crosslinking agent within the film layer reacted with the -OH and -COOH functional groups on the surface of layer B to form a covalently bonded chemically anchored layer, and was subsequently cured for more than 24 hours under conditions of 25 °C and 60% RH to achieve complete curing.

[0160] Through such control of construction conditions and reaction time, the film layer was completed not as a simple coating, but as a chemically integrated, environmentally resistant barrier layer.

[0162] Although the present invention has been described above with reference to the embodiments, it is understood that various modifications are possible within the scope of the technical spirit of the present invention. Explanation of the symbols

[0164] A: Primer layer B: Filler layer C: Film layer

Claims

Claim 1 A cross-sectional repair method for repairing a damaged area of ​​a concrete structure comprises: a primer layer applied to the surface of an existing concrete; a mortar filling layer formed on top of the primer layer to fill the damaged cross-section, wherein the filling layer is constructed using cement mortar under conditions of a wet-on-wet state prior to the primer layer's complete drying, i.e., a surface moisture content maintained in the range of 4 to 6%, and within 10 to 60 minutes after the application of the primer layer, thereby ensuring that the primer layer and the filling layer come into contact without being physically separated; and a film layer formed on top of the filling layer to protect the repair surface, applied when the surface residual moisture content of the filling layer is 6% or less; wherein the primer layer, the filling layer, and the film layer comprise an acrylic copolymer binder of the same series, and the primer layer and the film layer, excluding the filling layer, comprise a reactive crosslinking agent that forms interfacial crosslinking through a chemical reaction upon mutual contact, thereby forming a chemically integrated interlayer crosslinking structure at the interface of each layer, while the acrylic copolymer binder A concrete section repair method having an interfacial integrated structure, characterized in that it is composed of one or more of styrene-acrylate, methyl methacrylate-acrylate, ethyl acrylate-butyl acrylate, or acrylic acid-acrylate copolymers, and the reactive crosslinking agent is included in the primer layer and the film layer and reacts with at least one of a carboxyl group (COOH), a hydroxyl group (OH), an amide group (-C(=O)-NH-), or a silane functional group (-Si(OR)₃ or -Si-OH) included in the acrylic copolymer binder to form an interfacial crosslinking bond. Claim 2 delete Claim 3 delete Claim 4 A concrete section repair method having an interface-integrated structure, characterized in that, in claim 1, the reactive crosslinking agent is composed of one or more of amine-silane, phosphate, and zirconium compounds.

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