A rapid repair method for ship lock water conveying corridor facing plate based on sprayed recycled aggregate UHPC

Abstract

This invention provides a rapid repair method for the protective panels of a lock water conveyance corridor based on jet-recycled recycled aggregate (UHPC), belonging to the field of hydraulic structure repair technology. By employing jet-recycled UHPC, the superior performance of UHPC, derived from construction solid waste, is combined with the properties of UHPC. Utilizing specialized jetting equipment, efficient and durable repair of damaged protective panels is achieved. This method simultaneously overcomes the dual bottlenecks of traditional repair methods, such as the disconnect between materials and processes and limitations in formwork and casting construction. Through the deep integration of material-oriented design, collaborative optimization of construction processes, and UAV intelligent jetting technology, an integrated and efficient repair system of materials, processes, and equipment is constructed. This effectively solves technical problems such as low repair efficiency, poor material utilization, and unstable mechanical properties of the repair layer in high-altitude and complex structural areas. UAV jetting technology automates and intelligentizes the repair operation, significantly reducing labor costs and safety risks, and greatly enhancing the engineering application value and industrialization prospects of UHPC repair technology.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic structure repair technology, specifically relating to a fast, high-strength, and environmentally friendly repair material and construction method for concrete protective panels of lock water conveyance corridors. Background Technology

[0002] The protective panels of the lock's water conveyance corridor are subjected to high-speed water flow, silt erosion, cavitation, and the dry-wet cycle and freeze-thaw damage caused by water level changes over a long period of time. This makes them highly susceptible to surface peeling, exposed aggregate, cracks, and even structural damage. Traditional repair methods often use ordinary concrete or mortar, which have the following drawbacks:

[0003] Long repair cycle: Traditional processes rely excessively on cumbersome manual operations and lengthy material curing processes, resulting in long repair cycles and poor timeliness, which cannot meet the needs of emergency repairs, transportation hubs, and other engineering scenarios with strict time requirements.

[0004] Insufficient bonding strength between the old and new interfaces: Existing repair solutions have failed to effectively improve the microstructure of the interface between the old and new concrete, resulting in insufficient bonding strength and an inability to form effective mechanical transfer. This leads to poor synergistic performance between the repair layer and the original structure, making it difficult to meet the complex stress requirements such as impact resistance and fatigue resistance of the structure.

[0005] Poor durability: The impact and cavitation resistance of ordinary concrete is insufficient to meet the harsh working environment of the corridor. Existing repair solutions fail to fundamentally optimize the anti-deterioration performance of the repair system, resulting in the durability performance of the repaired structure failing to meet the design service life requirements and making it unsuitable for the repair needs of engineering structures in harsh environments such as bridges and harbor terminals.

[0006] Poor environmental performance: Existing remediation solutions fail to achieve the organic integration of resource recycling and low-carbon construction. They not only consume a large amount of non-renewable resources such as natural sand and gravel, but also increase energy consumption and pollutant emissions due to redundant procedures, making it difficult to meet the technical requirements of modern engineering for green, low-carbon and sustainable development.

[0007] High repair costs: Existing concrete structure damage repair technologies generally suffer from the industry pain points of "high energy consumption, high cost, and low efficiency": Traditional processes require large-scale demolition and removal of the damaged area, followed by multiple procedures such as formwork, rebar tying, secondary pouring, and curing. This not only consumes a large amount of human resources and equipment shifts, leading to a significant extension of the construction cycle, but also results in high overall costs due to material waste and redundant procedures. At the same time, conventional repair materials have insufficient compatibility with the original structure interface, which can easily cause secondary cracking and make it difficult to meet the development needs of long-term durability and green low-carbon engineering structures.

[0008] Therefore, developing an integrated repair technology that combines fast construction speed, high early strength, good durability, and environmental friendliness has become an urgent need to solve the problem of damage to the protective panels of the lock water conveyance corridor under the combined effects of high-speed water flow erosion, silt abrasion, cavitation erosion, and the combined effects of dry-wet freeze-thaw cycles. It is also an urgent need to ensure the long-term stable service of the corridor structure, improve the navigation efficiency of the lock, reduce the later operation and maintenance costs, and meet the development concept of green and low-carbon engineering construction.

[0009] In the existing technology, researchers have proposed applying drone technology to UHPC construction. For example, patent document CN119914075A filed by Southeast University discloses a UHPC jetting 3D printing device based on a drone. The device includes a drone body equipped with a flight control device, a real-time data transmission device, and a UHPC jetting device set below the drone. One end of the jetting device is connected to a high-precision jetting head, and the other end is connected to a UHPC pumping connection device through a jetting flow device and a power transmission device. The jetting speed and angle are controlled by a jetting speed adjustment device and a jetting angle control device, respectively.

[0010] However, the aforementioned existing technologies only provide a hardware platform for UHPC spraying and do not optimize the design for the special working condition of repairing the protective panels of the lock water conveyance channel. Specifically, the technology has the following defects: (1) It lacks a collaborative design with the lock protective panel repair materials (especially sprayed recycled aggregate UHPC), and cannot solve the problems of pipe blockage, segregation and interface bonding during the spraying process of recycled aggregate; (2) It does not consider the optimization of repair process parameters for the high-altitude and complex structural surfaces of the lock channel, and it is difficult to ensure the uniformity and density of the repair layer; (3) It does not involve the pretreatment process of the damaged base surface and the maintenance technology after repair, and cannot ensure the collaborative working performance of the repair body and the original structure. Summary of the Invention

[0011] The purpose of this invention is to provide a rapid repair method for the protective panels of lock water conveyance corridors based on sprayed recycled aggregate UHPC. This invention, building upon existing UAV spraying technology, optimizes the repair of protective panels for lock water conveyance corridors through an integrated design of materials, processes, and equipment. Compared with the existing technology CN119914075A, the ingenuity of this invention lies in: deeply integrating the aforementioned UAV spraying device with a specific sprayed recycled aggregate UHPC material system and repair process; achieving the triple technical goals of efficient construction, ultra-high strength bonding, and long-term durability by controlling specific process parameters such as the vertical distance between the nozzle and the repair surface (0.8-1.2m) and spiral trajectory layered spraying (single layer thickness ≤50mm); and simultaneously utilizing the resource utilization path of recycled construction waste aggregate to reduce solid waste emissions and dependence on natural sand and gravel resources, ultimately achieving a win-win situation of improved engineering repair performance and energy-saving and environmental benefits.

[0012] The above-mentioned objectives of the present invention are achieved through the following technical solutions:

[0013] A rapid repair method for the protective panel of a lock water conveyance channel based on jet-recycled aggregate UHPC includes the following steps:

[0014] S1. Removal of damaged concrete: Use a high-pressure water jet or a small milling machine to completely remove the damaged concrete until a solid base layer is exposed, forming a rough surface.

[0015] S2. Cleaning the chiseled surface: Use high-pressure air or clean water to thoroughly remove dust and debris from the chiseled surface;

[0016] S3. Pre-wetting the interface: 1-2 hours before spraying UHPC, the base surface should be thoroughly pre-wetted with water, but there should be no standing water on the surface;

[0017] S4. Pretreatment of recycled fine aggregate: The recycled fine aggregate is put into a ball mill for surface friction to remove the attached old mortar, and then soaked in sodium silicate solution for more than 24 hours, and then taken out and dried.

[0018] Preparation of S5.UHPC: UHPC comprises, by weight, 480-520 parts of cementitious material system, 1250-1350 parts of aggregate system, 8-12 parts of polycarboxylate-based high-performance water-reducing agent, 25-35 parts of reinforcing fiber, and water, wherein the water-cement ratio is controlled at 0.20-0.23; the cementitious material system comprises: 400-430 parts of cement, 50-60 parts of silica fume, and 30-40 parts of recycled micro powder; the aggregate system comprises: 450-500 parts of recycled fine aggregate and 800-850 parts of natural medium-coarse sand; the cementitious material system, aggregate system, polycarboxylate-based high-performance water-reducing agent, and reinforcing fiber are dry-mixed at a mixing plant, and then water is added for wet mixing to prepare homogeneous premixed UHPC;

[0019] S6. Transportation of UHPC: The premixed UHPC will be transported to the construction site by concrete mixer truck, and the mixing will be maintained during transportation;

[0020] S7. UHPC Spraying Construction: Spraying is performed using a UHPC spraying 3D printing device from a drone. At the nozzle of the UHPC spraying device, a liquid accelerator is uniformly mixed into the UHPC material stream using a metering pump. The amount of accelerator is 3%-6% of the mass of the cementitious material system. When spraying using the UHPC spraying 3D printing device from a drone, keep the nozzle perpendicular to the repair surface at a distance of 0.8-1.2 meters, and move slowly from top to bottom and from left to right in a spiral trajectory. Spraying is performed in layers, with a single layer thickness not exceeding 50mm.

[0021] S8. UHPC Surface Leveling: After the last layer of UHPC is sprayed, immediately use a scraper to perform preliminary leveling. When the UHPC begins to set and lose its plasticity, use a steel trowel to smooth and finish the surface.

[0022] S9.UHPC panel maintenance: 4-8 hours after construction, apply a curing agent for water retention and maintenance, with a maintenance period of no less than 7 days.

[0023] Furthermore, the sodium silicate solution used in step S4 has a mass fraction of 5%.

[0024] Furthermore, the recycled fine aggregate mentioned in step S5 has a particle size of 3-8 mm and is derived from waste concrete; the natural medium-coarse sand has a particle size of 0.15-5 mm.

[0025] Furthermore, the reinforcing fiber mentioned in step S5 is a hook-shaped steel fiber with an aspect ratio of 60-80.

[0026] Furthermore, the cement mentioned in step S5 is P·II52.5R or silicate cement.

[0027] Furthermore, the recycled micro powder mentioned in step S5 is obtained by crushing, washing and grading solid waste such as waste concrete, mortar or bricks generated during the demolition of buildings.

[0028] Furthermore, the accelerator mentioned in step S7 is an alkali-free or low-alkali liquid accelerator.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Short construction period: Compared with traditional processes that rely excessively on cumbersome manual operations and long curing cycles, the UHPC used in this invention has advantages such as excellent repair performance and simple curing process. The repair layer can form sufficient early strength within 2-4 hours after spraying, and can be put into use after 7 days of curing, which can efficiently meet the engineering scenarios with strict requirements for construction period, such as emergency repairs and transportation hubs.

[0031] 2. Enhanced bonding strength between new and old interfaces: Conventional repair materials have poor compatibility with the original structure interface, which easily leads to interface peeling and secondary cracking, making it difficult to meet the development requirements of long-term durability and green low-carbon engineering structures; while the UHPC of this invention, with its excellent interface bonding performance, density and toughness, can form a firm and stable overall bond with the original concrete, significantly improving the interface crack resistance and long-term durability of the structure.

[0032] 3. Excellent durability: Existing repair solutions generally suffer from insufficient durability, easy aging and peeling, and frequent maintenance in the later stages, making it impossible to achieve long-term reliable repair. However, UHPC, with its ultra-high strength, high density, and excellent anti-impact, anti-cavitation and anti-permeability properties, can significantly improve the long-term service life of the structure and reduce the total life cycle maintenance cost.

[0033] 4. Excellent environmental performance: The application of recycled aggregates not only achieves the organic unity of resource recycling and low-carbon construction, but also effectively reduces construction solid waste and environmental burden, thereby realizing the coordinated development of high-value utilization of solid waste resources and improvement of engineering structural performance.

[0034] 5. Low repair cost: This repair solution overcomes the shortcomings of existing concrete structure damage repair technologies, such as high energy consumption, high cost, and low efficiency. At the same time, it effectively solves the problems of high energy consumption, long cycle, and high cost of traditional repair processes, significantly improving economic efficiency and engineering practicality. Detailed Implementation

[0035] Example 1

[0036] The UHPC used in this embodiment 1 is composed of the following raw materials in parts by weight:

[0037] 480 parts of a cementitious material system (this cementitious material system provides a high-strength, dense matrix and optimizes workability). Among them:

[0038] 400 parts of P·II52.5R cement;

[0039] 50 parts silica fume;

[0040] 30 parts of recycled micro powder (made from solid waste such as waste concrete, mortar or bricks generated during building demolition, after crushing, washing and grading).

[0041] The aggregate system consists of 1250 parts, including:

[0042] 450 parts of recycled fine aggregate (particle size 3-8mm, derived from waste concrete; the surface of the recycled aggregate is rubbed with a ball mill to remove the attached old mortar, then soaked in a 5% sodium silicate solution for 24 hours, taken out and dried to enhance its bonding performance with the interface between new and old concrete).

[0043] 800 parts of natural medium-coarse sand (particle size 0.15-5mm).

[0044] Chemical admixtures (to ensure low water-cement ratio and rapid setting of concrete):

[0045] 8 parts of polycarboxylate-based high-performance water-reducing agent;

[0046] Alkali-free quick-setting agent 3.0%.

[0047] Reinforcing fibers (significantly improve the toughness, impact resistance, and crack resistance of concrete):

[0048] 25 portions of hook-shaped steel fiber (length 16mm, diameter 0.2mm, aspect ratio = length / diameter = 16 / 0.2 = 80).

[0049] The water-to-cement ratio is strictly controlled between 0.20 and 0.23 (an extremely low water-to-cement ratio is the key to achieving ultra-high strength).

[0050] The water-to-binder ratio is 0.200.

[0051] This example demonstrates the repair of a 5m² section of a water conveyance channel in a ship lock. 2 Taking a damaged area with an average chiseling depth of 8cm as an example, the steps in this embodiment are as follows:

[0052] (1) Removal of damaged concrete: Use high-pressure water jet to completely remove the damaged concrete until a solid base layer is exposed, forming a rough surface.

[0053] (2) Cleaning the chiseled surface: Use high-pressure air to thoroughly clean the dust and debris from the chiseled surface.

[0054] (3) Remove interface pre-wetting: One hour before spraying UHPC, the base surface should be fully pre-wetted with water, but there should be no standing water on the surface.

[0055] (4) Pretreatment of recycled fine aggregate: The recycled fine aggregate is put into a ball mill and the surface is rubbed by the ball mill to remove the attached old mortar. Then it is soaked in a sodium silicate solution with a mass fraction of 5% for 24 hours and then taken out and dried.

[0056] (5) Preparation of UHPC: The cementitious material system, aggregate system, polycarboxylate superplasticizer and reinforcing fiber are dry-mixed at the mixing plant in strict accordance with the mix proportion, and then water is added for wet mixing to prepare homogeneous premixed UHPC. (6) Transportation of UHPC: The premixed UHPC is transported to the construction site by concrete mixer truck, and the mixing is maintained during transportation.

[0057] (7) UHPC Spraying Construction: The concrete mixer truck transports the pre-mixed UHPC to the designated location, and a UHPC spraying 3D printing device (CN119914075A) is used for spraying. At the nozzle of the UHPC spraying device of the UHPC spraying 3D printing device, a liquid accelerator is evenly mixed into the UHPC material flow through a metering pump. The UHPC is moved to the repair surface through the platform operation, keeping the nozzle perpendicular to the repair surface. The nozzle is 0.8 meters away from the repair surface, and it moves slowly from top to bottom and from left to right in a spiral trajectory. The spraying time is about 40 minutes. During this process, the operating platform can transmit images in real time through the UHPC and make corresponding fine adjustments. The repair object in this example is a protective panel, which is usually not very thick. Generally, it is sufficient to spray to a design thickness of no more than 50mm in one go.

[0058] (8) UHPC surface leveling: After the last layer of UHPC is sprayed, immediately use a scraper to initially level the UHPC surface. When the UHPC begins to lose its plasticity after initial setting, use a steel trowel to smooth and finish the surface.

[0059] (9) UHPC Panel Curing: After the UHPC spraying construction is completed, on-site testing shows that the compressive strength reaches 21.6 MPa after 4 hours of spraying, followed by the application of a curing agent. After 24 hours, the repaired area is capable of withstanding the impact of conventional water flow, and the lock can resume navigation. After 28 days, core sampling tests show a compressive strength of 105 MPa and an interfacial bonding strength of 2.8 MPa; fully meeting the following design and usage requirements:

[0060] Highly efficient construction: In Example 1, the repair time for a single protective panel is significantly shorter than that of traditional methods. Furthermore, the UHPC repair layer develops rapidly in strength 2-4 hours after spraying, and can be put into operation after 7 days of curing, greatly shortening the construction cycle and meeting the needs of emergency repairs and rapid navigation in lock projects.

[0061] Ultra-high strength bonding: In Example 1, the bonding strength between UHPC and the original concrete interface reached 2.85 MPa, which is higher than that of ordinary repair materials, effectively avoiding interface peeling and secondary cracking.

[0062] Long-lasting durability: After 1,000 freeze-thaw cycles and 12 months of impact and abrasion tests, the strength retention rate of the repair layer in Example 1 is ≥90%. The impact and abrasion resistance of Example 1 is 3.5 times better than that of traditional repair, meeting the requirements for long-term service of water conveyance corridors.

[0063] Example 2

[0064] The UHPC used in this embodiment 2 is composed of the following raw materials in parts by weight:

[0065] 500 parts of a cementitious material system (this cementitious material system provides a high-strength, dense matrix and optimizes workability). Among them:

[0066] 415 parts of P·II52.5R cement;

[0067] 55 parts silica fume;

[0068] 35 parts of recycled micro powder (made from solid waste such as waste concrete, mortar or bricks generated during building demolition, after crushing, washing and grading).

[0069] The aggregate system consists of 1300 parts, including:

[0070] 475 parts of recycled fine aggregate (particle size 3-8mm, derived from waste concrete; the surface of the recycled aggregate was rubbed with a ball mill to remove the attached old mortar, then soaked in a 5% sodium silicate solution for 24 hours, and then dried to enhance its bonding performance with the interface between new and old concrete).

[0071] 825 parts of natural medium-coarse sand (particle size 0.15-5mm).

[0072] Chemical admixtures (to ensure low water-cement ratio and rapid setting of concrete):

[0073] 10 parts of polycarboxylate-based high-performance water-reducing agent;

[0074] Alkali-free quick-setting agent 4.5%.

[0075] Reinforcing fibers (significantly improve the toughness, impact resistance, and crack resistance of concrete):

[0076] 30 portions of hook-shaped steel fiber (length 16mm, diameter 0.2mm, aspect ratio = length / diameter = 16 / 0.2 = 80).

[0077] The water-to-cement ratio is strictly controlled between 0.20 and 0.23 (an extremely low water-to-cement ratio is the key to achieving ultra-high strength).

[0078] The water-to-binder ratio is 0.215.

[0079] This example demonstrates the repair of a 5m² section of a water conveyance channel in a ship lock. 2 Taking a damaged area with an average chiseling depth of 8cm as an example, the steps in this embodiment are as follows:

[0080] (1) Removal of damaged concrete: Use high-pressure water jet to completely remove the damaged concrete until a solid base layer is exposed, forming a rough surface.

[0081] (2) Cleaning the chiseled surface: Use high-pressure air to thoroughly clean the dust and debris from the chiseled surface.

[0082] (3) Remove interface pre-wetting: 1.5 hours before spraying UHPC, spray water to pre-wet the base surface, but there should be no standing water on the surface.

[0083] (4) Pretreatment of recycled fine aggregate: The recycled fine aggregate is put into a ball mill and the surface is rubbed by the ball mill to remove the attached old mortar. Then it is soaked in a sodium silicate solution with a mass fraction of 5% for 24 hours and then taken out and dried.

[0084] (5) Preparation of UHPC: The cementitious material system, aggregate system, polycarboxylate superplasticizer and reinforcing fiber are dry-mixed in strict accordance with the mixing ratio at the mixing station, and then water is added for wet mixing to prepare homogeneous premixed UHPC.

[0085] (6) Transportation of UHPC: The premixed UHPC will be transported to the construction site by concrete mixer truck, and the mixing will be maintained during transportation.

[0086] (7) UHPC Spraying Construction: The concrete mixer truck transports the pre-mixed UHPC to the designated location, and a UHPC spraying 3D printing device (CN119914075A) is used for spraying. At the nozzle of the UHPC spraying device of the UHPC spraying 3D printing device, a liquid accelerator is evenly mixed into the UHPC material flow through a metering pump. The UHPC is moved to the repair surface through the platform operation, keeping the nozzle perpendicular to the repair surface. The nozzle is 1.0 meter away from the repair surface, and it moves slowly from top to bottom and from left to right in a spiral trajectory. The spraying time is about 40 minutes. During this process, the operating platform can transmit images in real time through the UHPC and make corresponding fine adjustments. The repair object in this example is a protective panel, which is usually not very thick. Generally, it is sufficient to spray to a design thickness of no more than 50mm in one go.

[0087] (8) UHPC surface leveling: After the last layer of UHPC is sprayed, immediately use a scraper to initially level the UHPC surface. When the UHPC begins to lose its plasticity after initial setting, use a steel trowel to smooth and finish the surface.

[0088] (9) UHPC Panel Curing: After the UHPC spraying construction is completed, on-site testing shows that the compressive strength reaches 23.1 MPa after 4 hours of spraying, followed by the application of a curing agent. After 24 hours, the repaired area is capable of withstanding the impact of conventional water flow, and the lock can resume navigation. After 28 days, core sampling tests show a compressive strength of 122 MPa and an interfacial bonding strength of 2.6 MPa, fully meeting the following design and usage requirements:

[0089] Highly efficient construction: In Example 2, the repair time for a single protective panel is significantly shorter than that of traditional processes. Furthermore, the UHPC repair layer develops rapidly in strength 2-4 hours after spraying, and can be put into operation after 7 days of curing, greatly shortening the construction cycle and meeting the needs of emergency repairs and rapid navigation in lock projects.

[0090] Ultra-high strength bonding: In Example 2, the bonding strength between UHPC and the original concrete interface reached 2.73 MPa, which is higher than that of ordinary repair materials, effectively avoiding interface peeling and secondary cracking.

[0091] Long-lasting durability: After 1,000 freeze-thaw cycles and 12 months of impact and abrasion tests, the strength retention rate of the repair layer in Example 2 is ≥90%. The impact and abrasion resistance of Example 2 is 3.8 times higher than that of traditional repair, meeting the requirements for long-term service of water conveyance corridors.

[0092] Example 3

[0093] The UHPC used in this embodiment 3 is composed of the following raw materials in parts by weight:

[0094] 520 parts of a cementitious material system (this cementitious material system provides a high-strength, dense matrix and optimizes workability). Among them:

[0095] 430 parts of silicate cement;

[0096] 60 parts silica fume;

[0097] 40 parts of recycled micro powder (made from solid waste such as waste concrete, mortar or bricks generated during building demolition, after crushing, washing and grading).

[0098] 1350 parts of aggregate system, including:

[0099] 500 parts of recycled fine aggregate (particle size 3-8mm, derived from waste concrete; the surface of the recycled aggregate is rubbed using a ball mill to remove the attached old mortar, then soaked in a 5% sodium silicate solution for 24 hours, taken out and dried to enhance its bonding performance with the interface between new and old concrete).

[0100] 850 parts of natural medium-coarse sand (particle size 0.15-5mm).

[0101] Chemical admixtures (to ensure low water-cement ratio and rapid setting of concrete):

[0102] 12 parts of polycarboxylate-based high-performance water-reducing agent;

[0103] Alkali-free quick-setting agent 6.0%.

[0104] Reinforcing fibers (significantly improve the toughness, impact resistance, and crack resistance of concrete):

[0105] 35 portions of hook-shaped steel fiber (length 16mm, diameter 0.2mm, aspect ratio = length / diameter = 16 / 0.2 = 80).

[0106] The water-to-cement ratio is strictly controlled between 0.20 and 0.23 (an extremely low water-to-cement ratio is the key to achieving ultra-high strength).

[0107] The water-to-binder ratio is 0.230.

[0108] This example demonstrates the repair of a 5m² section of a water conveyance channel in a ship lock. 2 Taking a damaged area with an average chiseling depth of 8cm as an example, the steps in this embodiment are as follows:

[0109] (1) Removal of damaged concrete: Use high-pressure water jet to completely remove the damaged concrete until a solid base layer is exposed, forming a rough surface.

[0110] (2) Cleaning the chiseled surface: Use high-pressure air to thoroughly clean the dust and debris from the chiseled surface.

[0111] (3) Remove interface pre-wetting: Two hours before spraying UHPC, the base surface should be fully pre-wetted with water, but there should be no standing water on the surface.

[0112] (4) Pretreatment of recycled fine aggregate: The recycled fine aggregate is put into a ball mill and the surface is rubbed by the ball mill to remove the attached old mortar. Then it is soaked in a sodium silicate solution with a mass fraction of 5% for 24 hours and then taken out and dried.

[0113] (5) Preparation of UHPC: The cementitious material system, aggregate system, polycarboxylate superplasticizer and reinforcing fiber are dry-mixed in strict accordance with the mixing ratio at the mixing station, and then water is added for wet mixing to prepare homogeneous premixed UHPC.

[0114] (6) Transportation of UHPC: The premixed UHPC will be transported to the construction site by concrete mixer truck, and the mixing will be maintained during transportation.

[0115] (7) UHPC Spraying Construction: The concrete mixer truck transports the pre-mixed UHPC to the designated location, and a UHPC spraying 3D printing device (CN119914075A) is used for spraying. At the nozzle of the UHPC spraying device of the UHPC spraying 3D printing device, a liquid accelerator is evenly mixed into the UHPC material flow through a metering pump. The UHPC is moved to the repair surface through the platform operation, keeping the nozzle perpendicular to the repair surface. The nozzle is 1.2 meters away from the repair surface, and it moves slowly from top to bottom and from left to right in a spiral trajectory. The spraying time is about 40 minutes. During this process, the operating platform can transmit images in real time through the UHPC and make corresponding fine adjustments. The repair object in this example is a protective panel, which is usually not very thick. Generally, it is sufficient to spray to a design thickness of no more than 50mm in one go.

[0116] (8) UHPC surface leveling: After the last layer of UHPC is sprayed, immediately use a scraper to initially level the UHPC surface. When the UHPC begins to lose its plasticity after initial setting, use a steel trowel to smooth and finish the surface.

[0117] (9) UHPC Panel Curing: After the UHPC spraying construction is completed, on-site testing shows that the compressive strength reaches 22.8 MPa after 4 hours of spraying, followed by the application of a curing agent. After 24 hours, the repaired area is capable of withstanding the impact of conventional water flow, and the lock can resume navigation. After 28 days, core sampling tests show a compressive strength of 115 MPa and an interfacial bonding strength of 2.4 MPa, fully meeting the following design and usage requirements:

[0118] Highly efficient construction: In Example 3, the repair time for a single protective panel is significantly shorter than that of traditional methods. Furthermore, the UHPC repair layer develops rapidly in strength 2-4 hours after spraying, and can be put into operation after 7 days of curing, greatly shortening the construction cycle and meeting the needs of emergency repairs and rapid navigation in lock engineering projects.

[0119] Ultra-high strength bonding: In Example 3, the bonding strength between UHPC and the original concrete interface reached 2.55MPa, which is higher than that of ordinary repair materials, effectively avoiding interface peeling and secondary cracking.

[0120] Long-lasting durability: After 1,000 freeze-thaw cycles and 12 months of impact and abrasion tests, the strength retention rate of the repair layer in Example 3 is ≥90%. The impact and abrasion resistance of Example 3 is 3.6 times higher than that of traditional repair, meeting the requirements for long-term service of water conveyance corridors.

Claims

1. A rapid repair method for the protective panel of a lock water conveyance channel based on sprayed recycled aggregate UHPC, characterized in that, Includes the following steps: S1. Removal of damaged concrete: Use a high-pressure water jet or a small milling machine to completely remove the damaged concrete until a solid base layer is exposed, forming a rough surface. S2. Cleaning the chiseled surface: Use high-pressure air or clean water to thoroughly remove dust and debris from the chiseled surface; S3. Pre-wetting the interface: 1-2 hours before spraying UHPC, the base surface should be thoroughly pre-wetted with water, but there should be no standing water on the surface; S4. Pretreatment of recycled fine aggregate: The recycled fine aggregate is put into a ball mill for surface friction to remove the attached old mortar, and then soaked in sodium silicate solution for more than 24 hours, and then taken out and dried. Preparation of S5.UHPC: UHPC comprises, by weight, 480-520 parts of cementitious material system, 1250-1350 parts of aggregate system, 8-12 parts of polycarboxylate-based high-performance water-reducing agent, 25-35 parts of reinforcing fiber, and water, wherein the water-cement ratio is controlled at 0.20-0.23; the cementitious material system comprises: 400-430 parts of cement, 50-60 parts of silica fume, and 30-40 parts of recycled micro powder; the aggregate system comprises: 450-500 parts of recycled fine aggregate and 800-850 parts of natural medium-coarse sand; the cementitious material system, aggregate system, polycarboxylate-based high-performance water-reducing agent, and reinforcing fiber are dry-mixed at a mixing plant, and then water is added for wet mixing to prepare homogeneous premixed UHPC; S6. Transportation of UHPC: The premixed UHPC will be transported to the construction site by concrete mixer truck, and the mixing will be maintained during transportation; S7. UHPC Spraying Construction: Spraying is performed using a UHPC spraying 3D printing device from a drone. At the nozzle of the UHPC spraying device, a liquid accelerator is uniformly mixed into the UHPC material stream using a metering pump. The amount of accelerator is 3%-6% of the mass of the cementitious material system. When spraying using the UHPC spraying 3D printing device from a drone, keep the nozzle perpendicular to the repair surface at a distance of 0.8-1.2 meters, and move slowly from top to bottom and from left to right in a spiral trajectory. Spraying is performed in layers, with a single layer thickness not exceeding 50mm. S8. UHPC Surface Leveling: After the last layer of UHPC is sprayed, immediately use a scraper to perform preliminary leveling. When the UHPC begins to set and lose its plasticity, use a steel trowel to smooth and finish the surface. S9.UHPC panel maintenance: 4-8 hours after construction, apply a curing agent for water retention and maintenance, with a maintenance period of no less than 7 days.

2. The method according to claim 1, characterized in that, The sodium silicate solution used in step S4 has a mass fraction of 5%.

3. The method according to claim 1, characterized in that, The recycled fine aggregate mentioned in step S5 has a particle size of 3-8 mm and is derived from waste concrete; the natural medium-coarse sand has a particle size of 0.15-5 mm.

4. The method according to claim 1, characterized in that, The reinforcing fiber mentioned in step S5 is a hook-shaped steel fiber with an aspect ratio of 60-80.

5. The method according to claim 1, characterized in that, The cement mentioned in step S5 is P·II52.5R or silicate cement.

6. The method according to claim 1, characterized in that, The recycled micro powder mentioned in step S5 is produced by crushing, washing and grading solid waste such as waste concrete, mortar or bricks generated during the demolition of buildings.

7. The method according to claim 1, characterized in that, The accelerator mentioned in step S7 is an alkali-free or low-alkali liquid accelerator.