A civil engineering crack repair and reinforcement method

Abstract

The application discloses a civil engineering crack repairing and reinforcing method, which comprises a reinforcing structure, specifically comprises a surface forming structure recessed on the surface of a crack area, an accommodating cavity formed in the surface forming structure and communicated with the crack, a filling and bonding structure formed by filling a mixed slurry based on epoxy resin in the crack and the cavity and solidifying the mixed slurry, a fiber composite material structure reinforcing layer fixed on the surface of the forming structure and an original structure through a homologous adhesive layer, and an external protection structure arranged outside the reinforcing layer. The construction method comprises the following steps: forming the surface forming structure through grooving and joint cleaning; injecting a specially-made mixed slurry based on epoxy resin to form the filling and bonding structure with deep penetration and surface bearing functions; brushing a homologous adhesive and pasting the fiber reinforcing layer; and finally constructing an external protection layer. Through the multi-level collaborative design, the application solves the problems of incomplete repairing, easy interface peeling and poor durability in the traditional method, and realizes the radical repairing of the crack and the long-acting improvement of the structure performance.

Description

Technical Field

[0001] This invention relates to the field of civil engineering, specifically to a method for repairing and reinforcing cracks in civil engineering projects. Background Technology

[0002] In the field of civil engineering, cracks in concrete or masonry structures are a common problem caused by material aging, load changes, temperature stress, or foundation settlement. The presence of cracks not only affects the aesthetics of the structure, but also seriously weakens the integrity, durability, and load-bearing capacity of the structure, and may even induce corrosion of internal steel bars, accelerating the deterioration of structural performance.

[0003] Existing technologies for crack repair mainly include surface sealing, pressure grouting, and external bonding reinforcement. While these methods can improve crack problems to some extent, they generally suffer from poor synergy, incomplete repair, and insufficient long-term effectiveness. For example, conventional grouting materials struggle to balance fluidity, permeability, and bond strength, resulting in incomplete filling of deep cracks and the formation of internal defects. Furthermore, the reinforcement effect of simply bonding fiber-reinforced composite materials is highly dependent on the integrity of the reinforced substrate. If the repair quality within the crack area is poor, the reinforcement layer is prone to peeling and failure, creating new safety hazards.

[0004] In recent years, high-performance repair materials have been continuously developed to address the aforementioned problems. For example, patent CN202511984978.0 discloses "a DRMMA resin polymer mortar with impermeability and flexural strength and its preparation method." This patent provides a mortar material composed of composite aggregate, DRMMA resin adhesive, and curing agent, possessing high early strength, excellent impermeability, and good adhesion to concrete substrates. However, this technical solution and the corresponding material-based repair method still have limitations: First, it is essentially a high-performance filler or surface covering material, with limited penetration repair capabilities for complex cracks (especially deep, irregular cracks), making it difficult to ensure sufficient microscopic interlocking and chemical bonding between the repair material and the crack inner wall. Second, its function is relatively singular, mainly addressing the "filling and repair" problem, with limited contribution to the long-term structural reinforcement and overall restoration of the repaired area, lacking interfacial synergistic design with subsequent reinforcement measures (such as fiber reinforcement). Finally, its application is limited by crack width (for repairing cracks ≤ 5mm wide), and it has stringent requirements for construction conditions (such as substrate moisture content and flatness) and processes (such as the need for applying a special primer and strict curing procedures), making it difficult to adapt to complex and changing on-site environments. Therefore, developing a systematic solution that can achieve everything from microscopic repair to macroscopic enhancement, and from interfacial bonding to overall protection, is of great significance for improving the reliability, durability, and overall benefits of crack repair. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems by providing a method for repairing and reinforcing cracks in civil engineering.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a civil engineering crack repair and reinforcement structure, which is installed in the crack area of ​​the original structure, comprising: The surface-forming structure features a recessed area on the surface of the crack region, forming an internal receiving chamber that communicates with the crack. This structure provides a stable and regular forming space for subsequent filling, effectively removes loose portions around the crack, and significantly increases the bonding area between new and old materials, thereby improving the integrity and anchoring strength of the restoration.

[0007] The filling adhesive structure is filled inside the crack and the receiving cavity. It is formed by in-situ curing of a mixed slurry containing epoxy resin matrix, diluent and curing agent. This structure not only penetrates deep into the crack to achieve microscopic sealing, but also forms a macroscopic load-bearing body in the groove, realizing full-scale integrated repair from micro to macro, and effectively restoring the integrity of the structure.

[0008] The structural reinforcement layer is covered and fixed to the surface-formed structure and the outer surface of the original structure by an adhesive layer. As the main load-bearing layer, this layer can effectively transfer and disperse local stress to the surrounding intact structure, greatly improve the tensile and bending bearing capacity of the repaired area, and prevent cracks from developing again.

[0009] An external protective structure, located outside the structural reinforcement layer, provides a protective barrier against ultraviolet radiation, corrosion, and wear for the entire repair system, significantly improving long-term durability.

[0010] Furthermore, in the mixed slurry, the mass ratio of epoxy resin matrix to curing agent component is 100:(20-50), which ensures that the slurry has a good balance between excellent workability (flowability, permeability) and mechanical properties after curing.

[0011] Furthermore, the mixed slurry also includes a toughening agent and a silane coupling agent. The toughening agent improves the toughness and impact resistance of the cured material; the silane coupling agent forms a strong chemical bond between the epoxy resin and the concrete, greatly enhancing the interfacial bonding strength.

[0012] Furthermore, the epoxy resin matrix is ​​a bisphenol A or bisphenol F epoxy resin; the curing agent is a modified amine curing agent. This combination provides high bond strength, good mechanical properties, and room temperature curing characteristics.

[0013] Furthermore, the filling and bonding structure comprises an integrally formed deep-penetrating body and a surface carrier. The deep-penetrating body fills the depth of the crack and capillary gaps, while the surface carrier fills the receiving chamber and its top surface is flush with the original structure. This creates a functional gradient: the deep penetration achieves internal sealing, and the surface carrier provides a flat and solid base surface; the two work synergistically to optimize the repair effect.

[0014] Furthermore, the surface molding structure consists of U-shaped or V-shaped surface grooves opened along the crack, deeply covering the main area of ​​the crack. This facilitates construction, has a regular shape, and promotes uniform stress distribution.

[0015] Furthermore, it also includes grouting channels located inside the cracks and connected to the surface grooves. This ensures that the grout can fully fill the entire crack system from bottom to top, which is especially suitable for deep and wide cracks and avoids filling blind spots.

[0016] Furthermore, the structural reinforcement layer is a fiber composite sheet with edges extending beyond the contour of the surface-formed structure. This allows for more effective stress diffusion and transfer. The adhesive layer is made of the same material as the epoxy resin matrix in the filling adhesive structure. This ensures chemical compatibility and interfacial continuity between the repair, adhesive layer, and reinforcement, eliminates weak interfaces, and ensures reliable load transfer.

[0017] The present invention also provides a method for constructing the above-described structural system, comprising the following steps: S1. Structural Forming Steps: Create a surface-forming structure on the cracked area and clean the work surface. Create a clean and orderly construction interface.

[0018] S2. Material Filling Step: Mix epoxy resin component A and curing agent component B in a certain proportion to obtain a slurry, inject it into the cracks and surface molding structure, and cure to form a filled and bonded structure. This achieves dense filling and bonding of the material to the defective area.

[0019] S3. Enhanced Construction Steps: Apply a homologous adhesive to the surface of the repair area to form an adhesive layer, apply the structural reinforcement layer, and apply pressure for curing. A high-strength external reinforcement layer is formed through reliable bonding.

[0020] S4. Protective Treatment Steps: An external protective structure is constructed outside the structural reinforcement layer. This provides terminal protection and ensures long-term performance.

[0021] The advantages of this invention compared to the prior art are: This invention, through a systematic design of "surface grooving and shaping - gradient material filling - homogeneous interface bonding - fiber external reinforcement - overall long-term protection", organically combines high-performance repair materials with reinforcement technology to form a multi-layered synergistic composite structure, achieving the effect of treating cracks both superficially and fundamentally, and providing long-lasting reinforcement. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0023] This invention provides a structure for repairing and reinforcing cracks in civil engineering and its construction method. The system and method follow an integrated process flow of "grooving and crack cleaning, deep grouting and filling, surface bonding reinforcement, and long-term external protection." First, by grooving the crack area and creating grouting channels, a regular and clean physical foundation is constructed for the entire repair and reinforcement system. Second, a specially formulated high-performance epoxy grout is injected to form a core repair body that combines deep sealing and macroscopic load-bearing functions. Then, a large area of ​​fiber-reinforced material is bonded using a homologous adhesive, providing strong external structural reinforcement to the repaired area. Finally, a protective layer is applied to provide long-term protection for the entire system. This process forms a composite structural system that is progressive from the inside out and functionally synergistic, aiming to restore the integrity of the structure from its root and significantly improve its load-bearing capacity and durability.

[0024] like Figure 1 As shown, the civil engineering crack repair and reinforcement structure is set in the crack area of ​​the original structure and includes a surface forming structure, a filling and bonding structure, a structural reinforcement layer and an external protective structure constructed in sequence.

[0025] 1. The surface molding structure includes a U-shaped surface groove cut along the crack direction. A U-shaped groove, 30mm wide and 40mm deep, is chiseled directly above the crack using a concrete cutting machine, its depth completely covering the visible depth of the crack. The advantage of the U-shaped groove is that it provides a regularly shaped, clearly defined "mold" for subsequent filling material, significantly increasing the bonding area between the old and new materials. To further ensure dense filling, in deeper areas of the crack, a vertical injection channel with a diameter of 8mm is added using a drilling machine. This channel extends into the depth of the crack and connects to the bottom of the U-shaped groove. The advantage of the injection channel is that it provides a direct injection path for the grouting material to reach the depth of the crack, achieving full filling from bottom to top.

[0026] 2. The filling and bonding structure is formed by in-situ curing of the mixed slurry. The mixed slurry adopts a two-component epoxy system: Component A contains 100 parts by weight of bisphenol A type epoxy resin (E-51), 15 parts by weight of butyl glycidyl ether (reactive diluent), 5 parts by weight of liquid-terminated carboxyl-terminated nitrile butadiene rubber (toughening agent), and 2 parts by weight of γ-aminopropyltriethoxysilane (silane coupling agent); Component B is 30 parts by weight of polyamide-modified amine curing agent. During construction, components A and B are mixed in proportion at 20-25℃ and mechanically stirred for 5 minutes to obtain a homogeneous slurry.

[0027] Grout is injected through the injection channel using a manual grouting device. The grout first penetrates deep into the cracks and concrete capillaries, forming a deep-penetrating body that achieves microscopic sealing and "welding." Subsequently, the grout fills the U-shaped groove, forming a surface load-bearing body. After both solidify together, they form a filled and bonded structure, the top surface of which is polished to be flush with the original structure surface.

[0028] 3. After the infilled adhesive structure has fully cured and been sanded smooth, apply an epoxy resin adhesive of the same origin as the infill grout evenly to its surface and at least 100 mm wide of intact concrete surface to form an adhesive layer. The advantage of the adhesive layer is that it ensures the chemical compatibility and interfacial continuity of the materials from the concrete matrix to the reinforcing layer.

[0029] Next, 300g / m² unidirectional carbon fiber cloth was applied as a structural reinforcement layer onto the adhesive layer. During application, it was ensured that the fiber direction was perpendicular to the crack direction and that the cloth edge extended 150mm beyond the U-shaped groove outline. A special roller was used to press and vent air, allowing for full resin impregnation, and the mixture was cured at 20-25℃ for 24 hours. The advantage of structural reinforcement layer 7 is that its high tensile strength effectively transfers and disperses localized stress to a larger area of ​​the surrounding structure, significantly improving the overall load-bearing capacity of the region.

[0030] 4. Finally, apply a layer of weather-resistant epoxy mortar approximately 5mm thick to the cured carbon fiber cloth surface as an external protective structure. After smoothing and curing, this protective layer provides an effective physical barrier against ultraviolet rays, moisture, chemical corrosion, and mechanical wear for the internal repair and reinforcement system. Its advantage lies in significantly improving the long-term durability and appearance consistency of the entire repair system.

[0031] The multi-level composite structure system constructed through the above steps not only effectively seals the cracks but also restores the integrity of the structure from the root, achieving a synergistic improvement in load-bearing capacity and service life.

[0032] The present invention will now be described in detail with reference to embodiments and comparative examples. The embodiments and comparative examples described below are only for illustrating and comparing the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention.

[0033] Test substrates and general conditions: All tests used 150mm×150mm×550mm prism specimens made of C30 concrete. After standard curing for 28 days, through cracks with a width of 0.2-0.4mm and a depth of approximately 100mm were pre-cast using the three-point bending method. The treated specimens were then cured for 28 days at a temperature of (20±2)℃ and a relative humidity of (60±5)%, followed by testing. The ultimate bearing capacity test was performed using the three-point bending method with a span of 450mm.

[0034] Examples 1-3

[0035] Example 1 (Standard Implementation)

[0036] This embodiment fully implements the technical solution of the present invention.

[0037] 1. Surface forming structure: A U-shaped groove is chiseled along the crack, with a groove opening width of 30mm and a depth of 25mm. A vertical injection channel with a diameter of 8mm and a depth of 120mm is drilled in the middle of the crack at the bottom of the groove.

[0038] 2. Filler adhesive slurry: Component A: 100 parts E-51 epoxy resin, 12 parts benzyl glycidyl ether, 8 parts liquid-terminated carboxyl-terminated nitrile rubber, 2 parts KH-550 silane coupling agent. Component B: 35 parts polyamide-modified amine curing agent. A:B mixing ratio = 100:35.

[0039] 3. Structural reinforcement layer: 300g / ㎡ unidirectional carbon fiber cloth, with a total bonding width of 200mm (85mm beyond the edge of the U-shaped groove), using homologous epoxy adhesive.

[0040] 4. External protective structure: 3mm thick epoxy mortar.

[0041] Example 2 (V-groove and low viscosity formulation)

[0042] The main changes in this embodiment are in the tank shape and slurry formulation, in order to verify its adaptability to finer cracks.

[0043] 1. Surface forming structure: A V-shaped groove is chiseled, with an opening width of 20mm and a depth of 20mm. There is no independent grouting channel; grouting is guided by the sharp corner of the V-shaped groove.

[0044] 2. Filler adhesive slurry: Component A: 100 parts low-viscosity bisphenol F epoxy resin, 20 parts neopentyl glycol diglycidyl ether (to further reduce viscosity), 5 parts toughening agent, 1.5 parts KH-560 silane coupling agent. Component B: 25 parts fatty amine curing agent. A:B mixing ratio = 100:25.

[0045] 3. Structural reinforcement layer and external protective structure: Same as in Example 1.

[0046] Example 3 (Repair of Wide Cracks and High-Strength Formula)

[0047] This embodiment uses a grout formulation with higher load-bearing capacity for wider cracks.

[0048] 1. Surface molding structure: A U-shaped groove is chiseled, with a groove width of 50mm and a depth of 35mm, to accommodate more filler. Two parallel injection channels are provided.

[0049] 2. Filler adhesive slurry: Component A: 100 parts E-51 epoxy resin, 10 parts diluent, 12 parts nano rubber toughening agent, 3 parts silane coupling agent. Component B: 40 parts aromatic amine modified curing agent. A:B mixing ratio = 100:40.

[0050] 3. Structural reinforcement layer: A composite layer of carbon fiber cloth and a layer of glass fiber cloth are bonded together, with a total width of 250mm.

[0051] 4. External protective structure: Same as in Example 1.

[0052] Comparative Examples 1-3 (Standard Comparison Scheme)

[0053] Comparative Example 1 (Single filler of high-performance mortar)

[0054] Repair was performed using DRMMA resin polymer mortar, similar to the embodiment in the prior art patent CN202511984978.0. The optimal mixing ratio and process disclosed in that patent were followed, filling the cracks and smoothing the surface without any reinforcement or protective layer.

[0055] Comparative Example 2 (adhesion after conventional pressure grouting)

[0056] This represents the currently common two-step method of "grouting + steel / fiber bonding".

[0057] 1. Use commercial epoxy grout (resin:curing agent = 100:30) to pressure grout the cracks.

[0058] 2. After the slurry has cured, the surface is sanded, a matching adhesive is applied, and the same carbon fiber cloth (200mm wide) as in Example 1 is attached.

[0059] 3. No surface grooving treatment, no external protective layer.

[0060] Comparative Example 3 (External adhesive reinforcement only)

[0061] This represents a reinforcement method that only addresses the appearance.

[0062] 1. No filling treatment is applied to the cracks.

[0063] 2. Apply adhesive directly to the surface of the crack area and attach the same carbon fiber cloth (200mm wide) as in Example 1.

[0064] 3. No external protective layer.

[0065] Performance Testing and Comparative Analysis

[0066] After all specimens were treated and cured, mechanical properties and durability tests were conducted. The core data are summarized in the table below:

[0067] Note: The load-bearing capacity improvement rate is based on the untreated cracked specimen (100%); the durability test is a combined accelerated test of 30 cycles of dry and wet cycling and ultraviolet aging.

[0068] Results Analysis and Conclusions: 1. Comprehensive Load-Bearing Performance Advantages: The ultimate load-bearing capacity (40.1-45.8kN) and improvement rate (220%-252%) of the three embodiments are comprehensively and significantly higher than those of all comparative examples (28.1-36.8kN, 154%-202%). All embodiments exhibited ideal "concrete crushing" failure, indicating that the final strength of the repair and reinforcement system of this invention exceeds that of the concrete itself, and the material potential is fully utilized. In contrast, the comparative examples all experienced premature delamination failure at different interfaces, and the system strength was limited by the weak interfaces.

[0069] 2. Verification of interfacial bond reliability: The examples showed the highest tensile bond strength (4.0-4.5 MPa), and the failure mode was "cohesive failure within concrete" in all cases. This demonstrates the combined effect of the "surface-shaped structure" increasing mechanical interlocking, the "homogeneous material system" ensuring compatibility, and the "silane coupling agent" enhancing chemical bonding, achieving an interface strength exceeding that of concrete itself. The comparative examples showed lower interfacial strengths, and failure occurred at the bond interface.

[0070] 3. Adaptability of Formulation and Structure: Example 2, employing a V-groove and a low-viscosity formulation, demonstrated excellent repair effects on fine cracks, proving that the present invention can be optimized and adjusted according to crack characteristics. Example 3, with its reinforcement design for wide cracks, achieved the highest load-bearing capacity, showcasing the scalability of the solution.

[0071] 4. Outstanding long-term durability: The tested examples maintained a load-bearing capacity retention rate of 94%-96% after accelerated aging, which is directly attributed to the robust protection of the internal reinforcement system by the "external protective structure." Comparative examples 2 and 3, without a protective layer, showed significantly lower retention rates, indicating that environmental erosion severely weakens the interface and material properties.

[0072] The crack repair and reinforcement structural system and method provided by this invention, through an innovative systematic design of "grooving and shaping—gradient filling—homogeneous bonding—fiber reinforcement—overall protection," successfully solves the three core problems of traditional methods: incomplete repair, easy interface peeling, and poor long-term durability. Comparative data from the embodiments and comparative examples fully demonstrate that this invention has irreplaceable comprehensive advantages in improving structural bearing capacity, ensuring interface reliability, and extending service life, providing an efficient and reliable solution for the radical repair and performance improvement of civil engineering structures.

[0073] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for repairing and reinforcing cracks in civil engineering, comprising a reinforcement structure disposed in the crack area of ​​the original structure, characterized in that, include: The surface-formed structure is recessed on the surface of the crack area, and an accommodating chamber communicating with the crack is formed inside it. A filling adhesive structure is provided to fill the interior of the crack and the receiving cavity. The filling adhesive structure is formed by in-situ curing of a mixed slurry, which includes an epoxy resin matrix, a diluent, and a curing agent component. A structural reinforcement layer is attached to and fixed to the outer surface of the surface-formed structure and the original structure via an adhesive layer; and An external protective structure is provided on the side of the structural reinforcement layer that is away from the original structure.

2. The method for repairing and reinforcing cracks in civil engineering according to claim 1, characterized in that, In the mixed slurry, the mass ratio of the epoxy resin matrix to the curing agent component is 100:(20-50).

3. The method for repairing and reinforcing cracks in civil engineering according to claim 2, characterized in that, The mixed slurry also includes toughening agents and silane coupling agents.

4. The method for repairing and reinforcing cracks in civil engineering according to claim 3, characterized in that, The epoxy resin matrix is ​​bisphenol A type epoxy resin and / or bisphenol F type epoxy resin; the curing agent component includes modified amine curing agents.

5. The method for repairing and reinforcing cracks in civil engineering according to claim 1, characterized in that, The filling and bonding structure includes a deep penetrating body that fills the deep part of the crack and capillary gaps, and a surface carrier that fills the receiving cavity and whose top surface is flush with the original structure surface. The deep penetrating body and the surface carrier are integrally formed.

6. The method for repairing and reinforcing cracks in civil engineering according to claim 1, characterized in that, The surface forming structure includes U-shaped or V-shaped surface grooves opened along the direction of the crack, the depth of which covers the main depth region of the crack.

7. The method for repairing and reinforcing cracks in civil engineering according to claim 6, characterized in that, It also includes an injection channel located inside the crack, the injection channel being connected to the receiving chamber of the surface groove.

8. The method for repairing and reinforcing cracks in civil engineering according to claim 1, characterized in that, The structural reinforcement layer is a fiber composite sheet with its edges extending beyond the contour of the surface-formed structure; the adhesive layer is made of the same material as the epoxy resin matrix in the filling adhesive structure.

9. A method for constructing a civil engineering crack repair and reinforcement method as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Structural forming step: The surface forming structure is formed on the surface of the crack area, and the working surface is cleaned. S2. Material filling step: Component A, which contains an epoxy resin matrix, is mixed with component B, which contains a curing agent, to obtain a mixed slurry. The mixed slurry is then injected into the crack and the surface molding structure. After curing, the filling and bonding structure is formed. S3. Enhanced construction steps: Apply adhesive to the surface-formed structure and surrounding area to form the adhesive layer, apply the structural reinforcement layer onto the adhesive layer and apply pressure to cure; S4. Protective treatment steps: The external protective structure is formed by constructing the outer side of the structural reinforcement layer.

Images