Method and system for short-term and rapid improvement of the interfacial bond strength of concrete repairs

Abstract

This invention belongs to the field of concrete repair, and particularly relates to a method and system for rapidly improving the interfacial bond strength of concrete repair in a short period of time. The method for rapidly improving the interfacial bond strength of concrete repair includes layering a repair material onto the existing concrete repair surface; each layer of the repair material has an electrically conductive network composed of fibers; the fiber sizes of each layer of the electrically conductive network are different; after the repair material is poured, positive and negative electrode metal mesh sheets are inserted into the repair material; both the positive and negative electrode metal mesh sheets penetrate all the poured repair layers and are in contact with the existing concrete substrate repair surface; the positive and negative electrode metal mesh sheets are energized to generate gradient heat in each layer of the repair material, thereby achieving high bonding performance at the repair interface in a short period of time.

Description

Technical Field

[0001] This invention belongs to the field of concrete repair, and in particular relates to a method and system for rapidly improving the interfacial bond strength of concrete repair in a short period of time. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Major concrete infrastructure projects are often deployed in complex and challenging mountainous areas, operating in harsh environments. In such conditions, ordinary concrete is susceptible to freeze-thaw damage and salt corrosion. To ensure the continued safe operation of infrastructure under these circumstances, existing infrastructure needs to be repaired. Traditional repair materials struggle to overcome the interfacial barriers and generally have limited durability. Therefore, using ultra-high performance concrete (UHPC), characterized by high strength, high toughness, and high durability, offers a promising solution, overcoming the limitations of traditional repair materials and achieving high interfacial bonding performance. Specifically, UHPC materials often achieve early strength through steam curing and autoclaving. This curing process significantly improves the macroscopic properties and microstructure of UHPC repair materials. Under these conditions, UHPC achieves a high interfacial bond and a dense transition zone with the existing concrete.

[0004] In complex and challenging mountainous areas with large diurnal temperature variations and inadequate curing conditions, poor bonding between UHPC and existing concrete at the repair interface and a loose microstructure can lead to premature detachment of UHPC from the existing concrete, resulting in poor reinforcement and protection. This limits the application of UHPC in repairing concrete infrastructure. Early-strength agents can accelerate cement hydration to achieve early strength and high interfacial bonding performance in the early stages. However, their later strength is unstable and may adversely affect the long-term strength of UHPC. They also increase UHPC shrinkage and creep, which will increase internal stress at the repair interface, thus negatively impacting its effectiveness. In the prior art, application number 2023118038943, entitled "A Gradient Repair Method and Structure Based on Optimized Pore Structure of the Transition Zone of the Repair Interface," uses a first-gradient repair material and a second-gradient repair material that have undergone fluidized fusion treatment to solidify in one step, achieving low porosity at the interface. This increases the bonding area between the repair material and the existing concrete, enhances the mechanical interlocking force, and eliminates the need for surface roughening treatment. It significantly improves the bonding performance of the repair interface and ensures the full utilization of the repair material's performance. However, it still cannot rapidly improve the bonding strength of the cement-based repair material-existing concrete structure interface in the short term.

[0005] In summary, current cement-based repair solutions cannot quickly improve the interfacial bond strength between cement-based repair materials and existing concrete structures in the short term, and are not suitable for harsh mountainous environments. Summary of the Invention

[0006] To address the technical problems mentioned above, this invention provides a method and application for rapidly improving the interfacial bond strength of concrete repair. The construction method is simple, enabling efficient curing of cement-based repair materials in challenging mountainous areas. The heat distribution for curing the repair material from the interface to the surface exhibits a gradient, allowing for rapid on-site curing without steam curing to achieve high interfacial bond performance and ensuring the extended service life potential of the repair material is realized.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a method for rapidly improving the interfacial bond strength of concrete repair in a short period of time.

[0009] In one or more embodiments, a method for rapidly improving the interfacial bond strength of concrete repair in a short period of time includes:

[0010] Repair material is poured in layers on the existing concrete surface; each layer of repair material has an electrically conductive network made of fibers; the fiber dimensions of the electrically conductive network are different in each layer.

[0011] After the repair material is poured, positive and negative metal wire mesh are inserted into the repair material; both positive and negative metal wire mesh penetrate all the repair layers and are in contact with the existing concrete substrate repair surface.

[0012] By energizing the positive and negative metal wire mesh sheets, gradient heat is generated in each layer of the repair material to achieve high adhesion performance at the repair interface in a short period of time.

[0013] As one implementation method, at least two layers of repair material are poured onto the existing concrete repair surface.

[0014] As one implementation method, when two layers of repair material are poured on an existing concrete repair surface, the heat generated in each layer of repair material decreases progressively from the existing concrete repair surface outwards.

[0015] When at least three layers of repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of repair material is greater than that generated in the middle layers of repair material, starting from the existing concrete repair surface and moving outwards.

[0016] In one implementation, when two layers of repair material are poured onto an existing concrete repair surface, the layer of repair material adjacent to the existing concrete repair surface has an electrically conductive network composed of micro-nano-scale fibers.

[0017] As one implementation method, when two layers of repair material are poured on an existing concrete repair surface, the layer of repair material away from the existing concrete repair surface has an electrically conductive network composed of microscale fibers.

[0018] In one embodiment, the surfaces of the positive electrode metal wire mesh and the negative electrode metal wire mesh are coated with a conductive adhesive film.

[0019] In other embodiments, a method for rapidly improving the interfacial bond strength of concrete repair in a short period of time includes:

[0020] Repair material is poured in layers on the existing concrete repair surface; each layer of repair material has an electrically conductive network composed of fibers of the same size.

[0021] After the repair material is poured, a pair of wire mesh sheets is inserted into each layer of repair material. Each pair of wire mesh sheets is in contact with the bottom interface of the corresponding layer of repair material, and each pair of wire mesh sheets is kept insulated from other layers of repair material.

[0022] By connecting the metal mesh sheets of each layer of repair material to power sources with different voltage / power levels, gradient heat is generated in each layer of repair material to achieve high adhesion performance at the repair interface in a short period of time.

[0023] As one implementation method, at least two layers of repair material are poured onto the existing concrete repair surface.

[0024] As one implementation method, when two layers of repair material are poured on an existing concrete repair surface, the heat generated in each layer of repair material decreases progressively from the existing concrete repair surface outwards.

[0025] When at least three layers of repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of repair material is greater than that generated in the middle layers of repair material, starting from the existing concrete repair surface and moving outwards.

[0026] A second aspect of the present invention provides a system for rapidly improving the interfacial bond strength of concrete repair in a short period of time.

[0027] In one or more embodiments, a system for rapidly improving the interfacial bond strength of concrete repair in a short period of time includes:

[0028] Multi-layer repair material, which is poured in layers onto the existing concrete repair surface; and

[0029] A pair of metal wire mesh sheets, which are connected to a power source;

[0030] Each layer of the repair material has an electrically conductive network made of fibers;

[0031] When the fiber scales of the electrified networks in each layer are different, the wire mesh pairs penetrate all the poured repair layers and are in contact with the existing concrete substrate repair surface. When the wire mesh pairs are electrified, gradient heat is generated in each layer of repair material to achieve high bonding performance at the repair interface in a short period of time.

[0032] When the fiber size of each layer of the electrical network is the same, the number of metal mesh pairs is the same as the number of repair material layers, and each metal mesh pair is in contact with the bottom interface of its corresponding repair material layer. Each metal mesh pair is kept insulated from other repair materials. The metal mesh pairs of each repair material layer are connected to power supplies of different voltage / power levels, thereby generating gradient heat in each repair material layer to achieve high adhesion performance at the repair interface in a short period of time.

[0033] The beneficial effects of this invention are:

[0034] (1) The construction method of the present invention is simple. It utilizes the layered pouring of the repair material with the interconnection of the cross-scale fiber structure to generate gradient heat after being energized, which promotes the hydration of the repair material. Under the premise of meeting the normal performance requirements of the repair material, it realizes the efficient construction and maintenance of cement-based repair materials in difficult mountainous areas. The maintenance heat of the repair material from the interface to the surface presents a gradient distribution. The rapid on-site curing without steam curing achieves high bonding performance of the repair interface, ensuring the potential of the repair material to extend its service life.

[0035] (2) This invention utilizes the principle of heating through resistance to increase the curing temperature of the repair material, accelerate cement hydration, and regulate the generation rate of hydration products at the repair interface, thereby enhancing the performance of the interface transition zone and achieving high bonding performance of the repair interface.

[0036] (3) This invention does not use additives to rapidly improve the interfacial bonding strength in a short period of time, and will not affect the later shrinkage or creep of the repair material, thus ensuring the long-term effectiveness of the interfacial bonding.

[0037] (4) The repair material of the present invention is cast in multiple layers. By controlling the design of the conductive path or the input parameters of voltage / power for each layer of the repair material, the heat of each layer is different, and the overall heat distribution is gradient from the inside to the outside starting from the repair interface: for a two-layer structure, the heat generation decreases step by step from the interface to the outside; for a three-layer or higher structure, the heat generation of the innermost and outermost layers is greater than that of the middle layers, thus achieving the purpose of this gradient heat. In order to efficiently maintain the repair interface, the heat is higher in the area near the interface layer, which aims to improve the hydration process of the repair material and deposit more hydration products on the repair interface, so as to play the role of cement-based repair material and concrete base. The interlocking between the layers enhances the bonding performance of the repair interface. The top layer of the cement-based repair material is the part that is in direct contact with the outside world. Its heat exchange with the outside world is the most frequent among the layers of cement-based repair material. If the curing heat of the top layer is small, the overall mechanical properties of the repair material will vary greatly. In order to ensure the overall homogeneity of the mechanical properties of the repair material, the heat loss of the top layer of cement-based repair material will be controlled by controlling the material parameters or input voltage / power parameters. The heat generated is relatively greater than that of the adjacent layers, and the excess part is used for heat exchange loss with the outside world, thereby avoiding the phenomenon of temperature cracks in the top layer of cement-based repair material.

[0038] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 This is a schematic diagram of a method for pouring and curing repair materials according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of another method for pouring and curing repair materials according to an embodiment of the present invention;

[0042] Figure 3 This refers to the bonding performance of the repair interface between Example 1 and the control group of the present invention;

[0043] Figure 4 This refers to the porosity of the repair interface transition zone between Example 1 and the control group of the present invention.

[0044] Figure 5 This refers to the bonding performance of the repair interface between Example 2 and the control group of the present invention;

[0045] Figure 6 This refers to the porosity of the repair interface transition zone between Example 2 and the control group of the present invention. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] Terminology Explanation:

[0050] Fiber scale: The fiber scale is defined based on its size, where: the microscale is above the μm level and below the m level; and the microscale is below the μm level.

[0051] exist Figure 1 The paper presents a method for rapidly improving the interfacial bond strength in concrete repair in a short period of time, which includes the following steps:

[0052] Step 1: Pour the repair material in layers onto the existing concrete repair surface; each layer of repair material has an electrically conductive network made of fibers; the fiber size of the electrically conductive network in each layer is different.

[0053] In one or more embodiments, the preparation process of the existing concrete repair surface is as follows:

[0054] The existing concrete surface is roughened by hand or water jet roughening to obtain a rough repair surface. The base concrete is ordinary concrete.

[0055] exist Figure 1 In this embodiment, two layers of repair material are poured onto the existing concrete repair surface. While two layers are used in this embodiment, it is not limited to two layers; three, four, or even five or more layers can be applied. Those skilled in the art can determine the appropriate configuration based on the specific circumstances.

[0056] In one or more embodiments, starting from the existing concrete repair surface, the fiber size of each layer of the repair material is progressively increased from the inside out. This utilizes the difference in heat generation between the top layer, intermediate layers, and layers near the repair interface to achieve high interfacial adhesion, prevent cracking of the top layer repair material, maintain homogeneous mechanical properties of the overall repair material, and achieve better synergistic stress distribution, maximizing the reinforcing and protective potential of the repair material.

[0057] Taking the pouring of two layers of repair material on an existing concrete repair surface as an example:

[0058] Specifically, the repair material is poured in layers. The repair layer 1 material in the area near the repair interface has the characteristics of a connected electrical network composed of micro-nano scale fibers, and the repair layer 2 material has the characteristics of a connected electrical network composed of micro-scale fibers.

[0059] In one or more embodiments, the repair layer 1 material may be prepared using the following method:

[0060] 700-950 parts cement, 50-240 parts silica fume, 800-1100 parts sand, 90-180 parts steel fiber, 220-270 parts water, 20-36 parts water-reducing agent, and 1-3 parts carbon nanotubes.

[0061] In other embodiments, the repair layer 1 material can be prepared using the following method:

[0062] 750-900 parts cement, 80-220 parts silica fume, 850-1040 parts sand, 90-180 parts carbon fiber, 220-270 parts water, 20-36 parts water-reducing agent, and 1-3 parts nano-graphite sheets.

[0063] The mixing regime for repair layer 1 material is as follows:

[0064] Water, water-reducing agent and nanomaterials are first ultrasonically dispersed for 10-15 minutes; cement, silica fume and sand are dry-mixed for 5-10 minutes, the ultrasonically dispersed mixture is poured into the dry mix and stirred for 10-18 minutes, and then the fiber is added and stirred for 5-8 minutes.

[0065] It should be noted that those skilled in the art can set the various ingredients and their proportions in the repair layer 1 material according to the actual situation, which will not be described in detail here.

[0066] In one or more embodiments, the repair layer 2 material can be prepared using the following method:

[0067] 720-930 parts cement, 60-255 parts silica fume, 820-1200 parts sand, 60-140 parts steel fiber, 210-280 parts water, and 16-30 parts water-reducing agent.

[0068] In other embodiments, the repair layer 2 material can be prepared using the following method:

[0069] 710-920 parts cement, 60-230 parts silica fume, 810-1240 parts sand, 60-130 parts carbon fiber, 190-240 parts water, and 20-36 parts water-reducing agent.

[0070] The mixing regime for the repair layer 2 material is as follows:

[0071] Mix cement, silica fume, and sand dry for 5-10 minutes. Add water and water-reducing agent to the dry mix and mix for 10-18 minutes. Then add fiber and mix for 5-8 minutes.

[0072] It should be noted that those skilled in the art can set the various ingredients and their proportions in the repair layer 2 material according to the actual situation, which will not be described in detail here.

[0073] Step 2: After the repair material is poured, insert positive and negative metal wire mesh into the repair material; both positive and negative metal wire mesh penetrate all the repair layers and are in contact with the existing concrete substrate repair surface.

[0074] Step 3: Apply electricity to the positive and negative metal wire mesh sheets to generate gradient heat in each layer of repair material, so as to achieve high adhesion performance at the repair interface in a short period of time.

[0075] exist Figure 1 First, repair layer 1 is poured, then repair layer 2 is poured. After pouring, a wire mesh is inserted into the repair material. The wire mesh penetrates through repair layer 1 and repair layer 2, and is inserted all the way to the surface of the concrete substrate. The side length of the wire mesh hole spacing is less than the set threshold (e.g., 5mm, which can be set according to the actual situation).

[0076] The metal wire mesh serves to connect the power source and the repair material. In order to maximize the overlap of multi-scale fibers in the repair material, achieve efficient current transmission, form a closed circuit, and generate heat for curing, the metal wire mesh adopts a hollow design with a pore spacing smaller than a set threshold.

[0077] The repair material is covered with an insulation film, which can be made of rock wool, polyethylene, etc. The purpose is to prevent heat exchange between the top layer of repair material and the outside environment. This saves maintenance energy and prevents excessive heat loss, which could cause large temperature deformation and cracking of the repair material.

[0078] This embodiment employs a two-layer repair material casting method. Repair layer 1 is cast with micro-nano-scale fibers to form a connected electrical network, and repair layer 2 is cast with micro-scale fibers to form a connected electrical network. Due to the differences in fiber content and size in each repair material layer, the current channels formed in the repair material layers are different, resulting in differences in the heat generated by electricity. The overall repair material exhibits a gradient of heat, which can effectively maintain the repair interface while preventing the overall heat loss of the repair material from causing temperature cracks in the top layer material.

[0079] When two layers of repair material are poured on an existing concrete repair surface, the heat generated in each layer of repair material decreases gradually from the existing concrete repair surface outwards.

[0080] When at least three layers of repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of repair material is greater than that generated in the middle layers of repair material, starting from the existing concrete repair surface and moving outwards.

[0081] In this embodiment, the cast-in-place repair layer 1 generates more heat than the cast-in-place repair layer 2, promoting the hydration of the repair material. Thus, while meeting the normal performance requirements of the repair material, the repair interface can generate higher interfacial bonding strength. Under the action of electricity, the repair material can generate a gradient heat difference, thereby achieving high interfacial bonding performance in a short period of time while meeting the requirements for the use of the repair material.

[0082] In some embodiments, a conductive adhesive film is coated on the surface of the wire mesh. This film can act as a barrier between the wire mesh and the concrete, and also serves as a current conduction layer. However, the adhesion between the conductive film and the wire mesh is poor. After curing, the wire mesh is pulled out, and the conductive film layer remains in the concrete, thereby enabling the reusability of the wire mesh.

[0083] Figure 1 The curing process for the short-term rapid improvement of concrete repair interface bond strength is as follows:

[0084] The following are the construction parameter values ​​given for the application scenarios of the repair materials. For example, if the repair material is used in extremely cold regions, it will be suitable for curing under negative temperature conditions; if the repair material is used year-round in tropical or subtropical regions, it will be suitable for curing under positive temperature conditions. The two types of construction parameters are divided by whether the construction environment is below or above zero degrees Celsius. The difference in parameter design is mainly based on the fact that free water in the repair material mixture will freeze below zero degrees Celsius, causing slight volume expansion. If a positive temperature curing process is used, there is a potential hazard of deteriorating the microstructure of the repair material. Therefore, when construction is carried out in a negative temperature environment, the applied curing process parameters must ensure that the repair material is kept at a temperature above zero degrees Celsius to avoid the change from liquid phase to solid phase in the water in the repair material.

[0085] Repair materials should be cured under sub-zero temperatures:

[0086] After the repair material is poured, the wire mesh is connected to the power supply and energized with constant power or constant voltage. The power is 30W-80W, the voltage is 100V-220V, and the AC frequency is 45Hz-55Hz. The current passes through the repair material to generate heat, and the negative temperature curing cycle is 1-2 days.

[0087] Repair materials should be cured under positive temperature conditions:

[0088] The repair material is cured at a positive temperature for 12-24 hours. Then, the power supply is used for curing, with constant power or constant voltage. The power is 20W-60W, the voltage is 220V, and the AC power is 45Hz-55Hz. The curing cycle is 2-12 hours.

[0089] After the curing is completed, the repair material can enter normal service. The repair material and the existing structure have good interfacial bonding performance.

[0090] exist Figure 2 Another method for rapidly improving the interfacial bond strength of concrete repair is presented in the paper.

[0091] Another method for rapidly improving the interfacial bond strength of concrete repair in the short term includes:

[0092] Repair material is poured in layers on the existing concrete repair surface; each layer of repair material has an electrically conductive network composed of fibers of the same size.

[0093] After the repair material is poured, a pair of wire mesh sheets is inserted into each layer of repair material. Each pair of wire mesh sheets is in contact with the bottom interface of the corresponding layer of repair material, and each pair of wire mesh sheets is kept insulated from other layers of repair material.

[0094] By connecting the metal mesh sheets of each layer of repair material to power sources with different voltage / power levels, gradient heat is generated in each layer of repair material to achieve high adhesion performance at the repair interface in a short period of time.

[0095] Among them, at least two layers of repair material are poured on the existing concrete repair surface.

[0096] When two layers of repair material are poured on an existing concrete repair surface, the heat generated in each layer of repair material decreases gradually from the existing concrete repair surface outwards.

[0097] When at least three layers of repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of repair material is greater than that generated in the middle layers of repair material, starting from the existing concrete repair surface and moving outwards.

[0098] The metal wire mesh serves to connect the power source and the repair material. In order to maximize the overlap of multi-scale fibers in the repair material, achieve efficient current transmission, form a closed circuit, and generate heat for curing, the metal wire mesh adopts a hollow design with a pore spacing smaller than a set threshold.

[0099] exist Figure 2 In this process, two layers of repair material are poured onto the existing concrete repair surface. The following example uses wire mesh:

[0100] Repair layers 1 and 2 are made of the same repair material but need to be poured in two layers. After pouring, wire mesh 1 is inserted into the repair surface. The part of wire mesh 1 that contacts the poured repair layer 2 is coated with insulating material. Wire mesh 2 is then inserted into the top surface of the poured repair layer 1. Figure 2 As shown. Wire mesh pair 1 and wire mesh pair 2 are connected to different power sources for constant power or constant voltage curing. The power is 30W-80W, the voltage is 100V-220V, and the AC frequency is 45Hz-55Hz. However, the power or voltage applied to wire mesh pair 1 is 20%-40% lower than that applied to wire mesh pair 2.

[0101] Maintenance Mechanism: By constructing a cross-scale conductive network pathway, the conductivity of the repair material is regulated, thereby stimulating its electrothermal function. This electrothermal generation maintains the health of the repair material, promoting cement hydration and increasing the proportion of high-density and ultra-high-density zones within the hydration product, calcium silicate gel. The formation of hydration products such as hard calcium silicate and tobermorite further enhances the mechanical properties of the repair material. Conductive nanomaterials not only improve the electrical properties of the repair material but also act as physical fillers, accelerating cement hydration. Under high-heat curing, they accelerate the deposition of hydration products at the repair interface. In a short period of time, the bonding performance of the repair interface is improved at multiple scales. At the macro scale, there is no lack of slurry at the repair interface, and the mechanical interlocking force of the interface is increased. At the micro scale, the amount of hydration products embedded in the repair interface is relatively large, which increases the clamping force of the repair interface. At the micro scale, the transition zone of the repair interface is divided into three layers. The middle layer is prone to calcium hydroxide accumulation and high porosity. The middle layer is the limiting factor of the interface performance. Through electrothermal curing, calcium hydroxide is consumed, reducing the preferred orientation of calcium hydroxide, making the interface transition zone dense, and enhancing the mechanical interlocking force at the micro-nano scale.

[0102] Example 1:

[0103] The concrete surface to be repaired was roughened by hand to obtain a rough surface. Repair material was then poured in layers.

[0104] Repair layer 1 materials: 800 parts cement, 150 parts silica fume, 1000 parts sand, 160 parts steel fiber, 230 parts water, 28 parts water-reducing agent, and 2 parts carbon nanotubes. Mixing procedure: Water, water-reducing agent, and nanomaterials are first ultrasonically dispersed for 12 minutes; cement, silica fume, and sand are dry-mixed for 5 minutes; the ultrasonically dispersed mixture is then poured into the dry mixture and stirred for 12 minutes; finally, the fibers are added and stirred for 6 minutes.

[0105] Repair layer 2 materials: 820 parts cement, 130 parts silica fume, 1000 parts sand, 160 parts steel fiber, 240 parts water, and 29 parts water-reducing agent. Mixing procedure: Dry mix cement, silica fume, and sand for 6 minutes, then add water and water-reducing agent to the dry mix and mix for 12 minutes, then add fiber and mix for 6 minutes.

[0106] Repair layer 1 was poured first, followed by repair layer 2. After pouring, a wire mesh was inserted into the repair material, penetrating both repair layers 1 and 2 and extending to the concrete substrate surface. The repair material was then covered with a polyethylene film. The repair environment was a positive temperature environment, and the repair material was cured at this temperature for 22 hours. Then, a constant power supply of 30W, 55Hz AC was applied for curing for 3 hours. The control group was cured at room temperature (20℃) for 3 days. Pull-out tests were conducted at the repair interface to evaluate the interfacial adhesion performance and to analyze the microstructure of the repair interface. The experimental results are as follows: Figure 3 and Figure 4 As shown.

[0107] Analysis of experimental results:

[0108] The interfacial bond strength measured in Example 1 was 3.2 MPa, with matrix failure at the failure location, indicating good interfacial bond performance. In contrast, the interfacial bond strength of the control group was 2.2 MPa, with interfacial failure at the failure location. The method in Example 1, requiring only a 3-hour curing period, achieved interfacial bond strength that is 45% higher than the 3-day interfacial bond strength obtained using the traditional curing method. Analysis of the pore structure in the transition zone of the repair interface revealed that within the first 50 μm of the interface, the average porosity of the transition zone in Example 1 and the control group was 4.5% and 10.9%, respectively. The porosity of the transition zone in Example 1 was 58.7% lower than that in the control group, demonstrating the feasibility of a method for rapidly improving the interfacial bond strength of concrete repair in a short period.

[0109] Example 2:

[0110] The base concrete is ordinary concrete, and the concrete surface is roughened by high-pressure water jet to obtain a rough repair surface.

[0111] Repair layer 1 materials: 800 parts cement, 120 parts silica fume, 980 parts sand, 120 parts carbon fiber, 240 parts water, 30 parts water-reducing agent, and 3 parts nano-graphite sheets. Water, water-reducing agent, and nanomaterials are first ultrasonically dispersed for 13 minutes; cement, silica fume, and sand are dry-mixed for 8 minutes, and the ultrasonically dispersed mixture is poured into the dry mix and stirred for 12 minutes, then the fiber is added and stirred for 6 minutes.

[0112] Repair layer 2 materials: 860 parts cement, 180 parts silica fume, 960 parts sand, 110 parts carbon fiber, 220 parts water, and 28 parts water-reducing agent. Dry mix cement, silica fume, and sand for 8 minutes. Add water and water-reducing agent to the dry mix and mix for 13 minutes. Then add fiber and mix for 7 minutes.

[0113] First, pour repair layer 1, then pour repair layer 2. After pouring, insert wire mesh into the repair material, penetrating both repair layers 1 and 2, and extending all the way to the repaired surface of the concrete substrate. The side length of the wire mesh pores is less than 5mm. Cover the repair material with a polyethylene film. The repair material is cured under negative temperature conditions: After pouring the repair material, connect the wire mesh to a power source and apply a constant voltage of 220V, 50Hz AC. The current flows through the repair material, generating heat. The negative temperature curing period is 1 day. Perform a pull-out test on the repair interface to evaluate the interfacial bonding performance and analyze the microstructure of the repair interface. The experimental results are as follows: Figure 5 and Figure 6 As shown.

[0114] Analysis of experimental results:

[0115] In Example 2, the interfacial bond strength was measured at 2.9 MPa, with matrix failure at the failure location, indicating good interfacial bond performance. In contrast, the interfacial bond strength of the control group was 1.1 MPa, with interfacial failure at the failure location. Using the method in Example 2, the interfacial bond strength achieved in just 1 day of curing was 164% higher than that achieved by the natural curing method in 1 day. Analysis of the pore structure in the transition zone of the repair interface revealed that within the first 50 μm of the interface, the average porosity of the transition zone in Example 2 and the control group was 6.3% and 13.6%, respectively. The porosity of the transition zone in Example 2 was 53.7% lower than that in the control group. Electrothermal curing promoted cement hydration at the repair interface and the formation of hydration products, resulting in a denser transition zone. This demonstrates a method for rapidly improving the interfacial bond strength of concrete repair in a short period.

[0116] In one or more embodiments, a system for rapidly improving the interfacial bond strength of concrete repair is also provided, comprising:

[0117] Multi-layer repair material, which is poured in layers onto the existing concrete repair surface; and

[0118] A pair of metal wire mesh sheets, which are connected to a power source;

[0119] Each layer of the repair material has an electrically conductive network made of fibers;

[0120] When the fiber scales of the electrified networks in each layer are different, the wire mesh pairs penetrate all the poured repair layers and are in contact with the existing concrete substrate repair surface. When the wire mesh pairs are electrified, gradient heat is generated in each layer of repair material to achieve high bonding performance at the repair interface in a short period of time.

[0121] When the fiber size of each layer of the electrical network is the same, the number of metal mesh pairs is the same as the number of repair material layers, and each metal mesh pair is in contact with the bottom interface of its corresponding repair material layer. Each metal mesh pair is kept insulated from other repair materials. The metal mesh pairs of each repair material layer are connected to power supplies of different voltage / power levels, thereby generating gradient heat in each repair material layer to achieve high adhesion performance at the repair interface in a short period of time.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for rapidly improving the interfacial bond strength in concrete repair in a short period of time, characterized in that, include: A cement-based repair material is poured in layers on the existing concrete repair surface; each layer of cement-based repair material has an electrically conductive network composed of fibers; the fiber size of the electrically conductive network in each layer is different; After the cement-based repair material is poured, positive and negative metal wire meshes are inserted into the cement-based repair material; both positive and negative metal wire meshes penetrate all the poured repair layers and are in contact with the existing concrete substrate repair surface. By energizing the positive and negative metal wire mesh sheets, gradient heat is generated in each layer of cement-based repair material to achieve high adhesion performance at the repair interface in a short period of time.

2. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 1, characterized in that, Pour at least two layers of cement-based repair material onto the existing concrete repair surface.

3. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 1 or 2, characterized in that, When two layers of cement-based repair material are poured on an existing concrete repair surface, the heat generated in each layer of cement-based repair material decreases gradually from the existing concrete repair surface outwards. When at least three layers of cement-based repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of cement-based repair material is greater than that generated in the middle layers of cement-based repair material, starting from the existing concrete repair surface and moving outwards.

4. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 2, characterized in that, When two layers of cement-based repair material are poured onto an existing concrete repair surface, the layer of cement-based repair material adjacent to the existing concrete repair surface has an electrically conductive network composed of micro-nano-scale fibers.

5. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 2, characterized in that, When two layers of cement-based repair material are poured onto an existing concrete repair surface, the layer of cement-based repair material away from the existing concrete repair surface has an electrical network composed of microscale fibers.

6. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 1, characterized in that, The positive and negative metal wire mesh sheets are coated with a conductive adhesive film.

7. A method for rapidly improving the interfacial bond strength in concrete repair in a short period of time, characterized in that, include: A cement-based repair material is poured in layers on the existing concrete repair surface; each layer of the cement-based repair material has an electrically conductive network composed of fibers of the same size. After the cement-based repair material is poured, a pair of metal wire mesh is inserted into each layer of cement-based repair material. Each pair of metal wire mesh is in contact with the bottom interface of its corresponding layer of cement-based repair material, and each pair of metal wire mesh is kept insulated from other layers of cement-based repair material. By connecting the metal mesh sheets of each layer of cement-based repair material to power sources with different voltage / power levels, gradient heat is generated in each layer of cement-based repair material to achieve high adhesion performance at the repair interface in a short period of time.

8. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 7, characterized in that, Pour at least two layers of cement-based repair material onto the existing concrete repair surface.

9. The method for rapidly improving the interfacial bond strength of concrete repair as described in claim 7, characterized in that, When two layers of cement-based repair material are poured on an existing concrete repair surface, the heat generated in each layer of cement-based repair material decreases gradually from the existing concrete repair surface outwards. When at least three layers of cement-based repair material are poured on an existing concrete repair surface, the heat generated in the innermost and outermost layers of cement-based repair material is greater than that generated in the middle layers of cement-based repair material, starting from the existing concrete repair surface and moving outwards.

10. A system for rapidly improving the interfacial bond strength of concrete repair in a short period of time, characterized in that, include: Multi-layer cement-based repair material, which is poured in layers onto the surface of existing concrete for repair. and A pair of metal wire mesh sheets, which are connected to a power source; Each layer of cement-based repair material has an electrically conductive network made of fibers. When the fiber scales of the electrified networks in each layer are different, the wire mesh pairs penetrate all the poured repair layers and are in contact with the existing concrete substrate repair surface. When the wire mesh pairs are electrified, gradient heat is generated in each layer of cement-based repair material to achieve high bonding performance at the repair interface in a short period of time. When the fiber size of each layer of the electrical network is the same, the number of metal mesh pairs is the same as the number of cement-based repair material layers, and each layer of metal mesh pairs is in contact with the bottom interface of its corresponding layer of cement-based repair material. Each layer of metal mesh pairs is kept insulated from other layers of cement-based repair material. Each layer of cement-based repair material's metal mesh pairs is connected to a power source with different voltage / power levels, thereby generating gradient heat in each layer of cement-based repair material to achieve high adhesion performance at the repair interface in a short period of time.

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