Low-shrinkage ecological type UHPC bridge deck slab and preparation method thereof

Abstract

This invention discloses a low-shrinkage eco-friendly UHPC bridge deck and its preparation method. This invention relates to the field of concrete materials technology. Through gradient active solid waste pretreatment, gradient dry / wet mixing process, formwork-free casting, layered vibration compaction, and full-age steam-free gradient curing, it achieves integrated low-carbon preparation of high-solid-waste, low-shrinkage UHPC bridge decks. The advantages of this invention are: through the material system design of gradient active solid waste compounding, dual-source expansion regulation, load-type internal curing, and three-level hybrid fiber synergy, it specifically solves the core industry defect of existing eco-friendly UHPCs that cannot simultaneously achieve high solid waste content and ultra-low shrinkage crack resistance. It breaks the technical prejudice that large amounts of industrial solid waste inevitably lead to a surge in shrinkage rate and increased cracking risk. While significantly improving the utilization rate of industrial solid waste and reducing cement usage, it inhibits the plastic shrinkage, autogenous shrinkage, and drying shrinkage of UHPC from the root of hydration.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, specifically to a low-shrinkage eco-friendly UHPC bridge deck and its preparation method. Background Technology

[0002] Ultra-high performance concrete (UHPC), a novel cement-based composite material possessing ultra-high strength, high toughness, high durability, and high impermeability, has become the core preferred material for precast bridge deck engineering applications. With its lightweight and high-strength advantages, UHPC bridge decks can significantly reduce the structural thickness of traditional concrete bridge decks, substantially reducing the self-weight of the bridge superstructure and decreasing the load and construction costs of the substructure. Furthermore, its excellent crack resistance and corrosion resistance greatly enhance the long-term service stability of bridge decks in complex service environments such as nearshore areas, high humidity, and heavy loads. Currently, it has been widely promoted and applied in various engineering fields, including prefabricated highway bridges, municipal landscape bridges, steel trestle bridge reconstruction and expansion, and reinforcement and renovation of existing old bridges, forming a mature engineering application system and technical specifications. Existing UHPC bridge deck fabrication technologies primarily achieve high strength, high toughness, and durability through a high-percentage silicate cement cementitious system design, conventional uniform reinforcement structures, and high-temperature steam curing processes. However, these technologies have certain drawbacks. First, existing eco-friendly UHPCs cannot simultaneously achieve high solid waste content and ultra-low shrinkage crack resistance. High levels of industrial solid waste can easily lead to a surge in the shrinkage rate of the cementitious system, increasing the risk of cracking and making it impossible to achieve stable control of the hydration process and precise compensation for shrinkage deformation throughout the entire life cycle. Second, the existing UHPC bridge deck structural design is disconnected from the material's shrinkage characteristics, easily leading to shrinkage stress concentration cracking. The fabrication process is highly dependent on high-temperature steam curing, resulting in high energy consumption and carbon emissions, low efficiency in prefabricated construction and installation, and insufficient low-carbon performance and service stability throughout the entire life cycle. Therefore, we propose a low-shrinkage eco-friendly UHPC bridge deck and its fabrication method. Summary of the Invention

[0003] The purpose of this invention is to provide a low-shrinkage eco-friendly UHPC bridge panel and its preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a low-shrinkage, eco-friendly UHPC bridge panel, the method comprising the following steps: Step 1: Raw material pretreatment and precise weighing. The components of the composite active solid waste admixture are dried and ground separately. The composite active solid waste admixture includes steel slag powder, fly ash, slag, and silica fume. A gradient activity system is formed by controlling the specific surface area of ​​each component. Simultaneously, the pre-preparation of the loaded internal curing component is completed. Porous regenerated powder and superabsorbent resin are uniformly mixed in a certain proportion, pre-soaked in a saturated calcium hydroxide solution, filtered, and then air-dried until saturated. After clarifying the quality control indicators of each raw material, all raw materials are precisely weighed according to the preset formula. Step 2: Gradient dry mixing premixing process, which completes the dry mixing operation in two stages. First, the uniform stacking of gel powder and recycled fine aggregate is achieved, and then the three-dimensional uniform dispersion of composite mixed fibers is achieved to obtain dry mixing premix without component separation. Step 3: Gradient wet mixing plasticization process, which involves adding water and mixing in two stages. First, the matrix is ​​initially hydrated and uniformly plasticized, and then the load-bearing internal curing components are uniformly dispersed throughout the entire area to obtain a UHPC mixture with stable working performance. Step 4: Integrated mold assembly and steel reinforcement cage pre-embedding. Complete the mold assembly, precise positioning of the gradient reinforcement cage and various pre-embedded parts, and achieve formwork-free casting by using recycled steel edging. Step 5: Layered casting and high-frequency vibration. Layered casting is combined with high-frequency vibration to simultaneously mold the shrinkage stress release groove on the slab surface, thus completing the integrated casting and molding of the bridge deck. Step Six: Gradient-adaptive steam-free curing throughout the entire age period, divided into four stages precisely matched with the hydration process of the gelling system, to complete the entire process of steam-free, low-carbon curing and achieve full-cycle shrinkage inhibition; Step 7: Finished product performance testing and factory control. Conduct full performance testing and data verification on the finished products after maintenance. Products are allowed to leave the factory only after all indicators meet the standards.

[0005] As a further aspect of the present invention: In step one, the specific surface area of ​​steel slag powder is controlled to be 400-500 m² / kg, the specific surface area of ​​fly ash is controlled to be 500-600 m² / kg, and the specific surface area of ​​ultrafine slag and silica fume is controlled to be 700-800 m² / kg, forming a gradient activity system with low activity, medium activity, and high activity; the porous regenerated powder and superabsorbent resin are uniformly mixed at a mass ratio of 5-6:1, pre-soaked in a saturated calcium hydroxide solution for 2-3 hours, filtered, and then air-dried at room temperature under ventilation until saturated surface dryness, to avoid early water release of the internal curing components affecting the strength development of the cementitious system; Subsequently, the quality control indicators for all raw materials were clarified. The silicate cement was selected as P·O52.5 grade, the water reduction rate of the polycarboxylate superplasticizer was ≥30%, the recycled fine aggregate was selected as either tailings sand or recycled concrete powder, the fineness modulus was controlled at 2.3-2.8, and the gradation was continuous. The composite mixed fiber was compounded according to the mass ratio of recycled steel fiber: high-strength polypropylene coarse fiber: polyvinyl alcohol microfiber (60-70): (20-25): (5-15), and the dual-source expansion control component was compounded according to the mass ratio of light-burned magnesium oxide expansion agent: ettringite type expansion agent (2-3): 1. According to the preset formula, weigh 200-350 parts of silicate cement, 450-600 parts of composite active solid waste admixture, 5-15 parts of nano-active modifier, 8-25 parts of dual-source expansion regulating component, 3-12 parts of load-type internal curing component, 10-25 parts of polycarboxylate-based high-performance water-reducing agent, 120-160 parts of mixing water, 100-160 parts of composite mixed fiber, and 650-800 parts of recycled fine aggregate to complete the raw material preparation before preparation.

[0006] As a further aspect of the present invention: In step two, specifically: the weighed silicate cement, composite active solid waste admixture, nano-active modifier, dual-source expansion control component, and recycled fine aggregate are put into a horizontal forced mixer at one time. The main shaft speed of the mixer is set to 45-55 r / min, and the first stage of dry mixing is started. The dry mixing time is strictly controlled within 60-90 seconds, so that various powder materials and recycled fine aggregate are fully mixed to form a continuous and compact particle gradation packing system, completing the pre-construction of the cementitious powder skeleton and providing a uniform reaction basis for the subsequent gradient hydration reaction. After the first stage of dry mixing is completed, keep the mixer speed constant and sprinkle the weighed composite mixed fibers into the mixer cavity in 2-3 times at a uniform speed. Start the second stage of dry mixing and control the dry mixing time to 30-60 seconds to ensure that the three-dimensional mixed fibers are uniformly dispersed in the powder skeleton, without fiber agglomeration or unidirectional orientation. Finally, a uniformly dispersed dry premix without component separation is obtained, which provides a homogeneous basis for subsequent wet mixing operations.

[0007] As a further aspect of the present invention: In step three, specifically: the spindle speed of the horizontal forced mixer is kept at 40-50 r / min, and the pre-mixed polycarboxylate-based high-performance water-reducing agent and the mixing water accounting for 80% of the total mixing water are added at a uniform speed to the dry-mixed premix prepared in step two, and the first stage of wet mixing operation is started. The wet mixing time is controlled at 90-120s, so that the mixing liquid and the powder skeleton can be fully contacted and wetted, and the initial hydration reaction of the cementitious material and the uniform plasticization of the matrix are completed, so as to obtain a matrix slurry with stable initial fluidity, and avoid the problems of powder agglomeration and uneven hydration caused by adding water at one time; After the first stage of wet mixing is completed, the mixer speed is kept constant. The remaining 20% ​​of the mixing water is mixed with the pre-prepared load-type internal curing component to form a uniform suspension, which is then added to the matrix slurry at a uniform speed. The second stage of wet mixing is then started. The wet mixing time is controlled at 60-90 seconds to ensure that the load-type internal curing component is uniformly dispersed throughout the slurry and to avoid abnormal local water release. Finally, a low-shrinkage eco-friendly UHPC mixture with an expansion of 650±50mm, no segregation, no bleeding, and stable working performance is obtained, providing a homogeneous material for casting.

[0008] As a further aspect of the present invention: Step four specifically involves: assembling and positioning the steel mold on a horizontal precast platform; pre-laying a molded anti-slip patterned base film on the inner bottom surface of the mold; cleaning debris and dust from the mold cavity; uniformly applying a special release agent to the inner wall of the mold and the surface of the base film; and then smoothly hoisting the pre-welded asymmetric dual-dimensional gradient reinforced steel skeleton into the mold cavity. The edge reinforcement zone of the steel skeleton corresponds to the high-risk area of ​​shrinkage stress and the area of ​​negative bending moment concentration in the bridge deck; the transition reinforcement zone corresponds to the shrinkage stress transition zone and the positive bending moment transition zone; and the central optimized reinforcement zone corresponds to the low-risk area of ​​shrinkage stress. Simultaneously with the peak bending moment region, the recycled steel U-shaped edging, hoisting straight threaded sleeve, guardrail post pre-embedded holes, and pipeline reserved holes, which are welded and fixed to the reinforcing steel skeleton, are precisely positioned and installed. The recycled steel edging is equipped with a dovetail-shaped mechanical interlocking groove on the inner side, with the interlocking groove facing the inner cavity of the mold. The edging also serves as a side mold to achieve formwork-free casting, eliminating the need for additional side molds. Concrete protective layer spacers with a thickness of 15-20mm are evenly placed on the upper and lower layers of the reinforcing steel skeleton to ensure that the reinforcing steel skeleton is centered and the thickness deviation of the protective layer is controlled within ±2mm. Finally, the integrated assembly of the mold and the pre-embedded system is completed, providing a structural foundation for casting.

[0009] As a further aspect of the present invention: In step five, specifically: the low-shrinkage eco-friendly UHPC mixture obtained in step three is uniformly transported to the mold cavity assembled in step four through an integrated material receiving and spreading machine. Full-section casting is carried out using a layered casting method, with the thickness of each layer strictly controlled at 40-50mm. Immediately after each layer is cast, an immersion-type high-frequency vibrator is used for vibration. The vibration frequency of the vibrator is controlled at 50-60Hz, and the vibration time at a single point is controlled at 20-30s. During the vibration process, the vibrator is vertically inserted into the lower layer of cast mixture by 5-10mm to ensure tight interlayer bonding, no vibration blind spots, and no construction cold joints. Vibration continues until there are no obvious large air bubbles overflowing or obvious settling on the surface of the mixture. Over-vibration is strictly prohibited throughout the process to prevent fiber settling and aggregate segregation. After the full-section casting is completed, a mechanical scraper is used to initially level the slab surface. After standing for 30-60 minutes until the mixture initially sets, mechanical finishing and manual finishing are completed. At the same time, a special shaping mold is used to mold micro stress relief grooves perpendicular to the shrinkage stress direction on the slab surface. The stress relief grooves are 2-3mm deep, 5-8mm wide, and spaced 200-300mm apart, thus completing the integrated casting and molding of the bridge deck.

[0010] As a further aspect of the present invention: Step six specifically involves: immediately after casting and molding, entering a full-process non-steam curing, low-carbon gradient curing process. The curing process is divided into four continuous stages precisely adapted to the hydration process and expansion reaction rate of the cementitious system. The first stage is the pre-setting moisturizing curing stage, where non-woven geotextile and sealing plastic film are immediately covered on the finished bridge deck surface. The curing environment temperature is controlled at 20±5℃, the relative humidity is ≥95%, and the curing time is controlled at 12-18 hours. Surface air flow is completely isolated throughout the process, avoiding… To prevent rapid evaporation of surface moisture and inhibit plastic shrinkage cracking at its source, the second stage is the ambient temperature curing stage, maintaining a curing environment temperature of 20±5℃ and relative humidity ≥90%, continuing curing in the formwork for 24-36 hours until the compressive strength of the test blocks cured under the same conditions as the bridge deck reaches ≥40MPa. After completing the curing in the formwork, the formwork is removed. The third stage is the post-removal hydration-promoting and moisture-retaining curing stage. Immediately after removal from the formwork, a water-based concrete curing agent is evenly sprayed onto the entire surface of the bridge deck, with the spraying amount controlled at 0.3-0.5kg / m². 2 The material is then covered again with non-woven geotextile and sealing plastic film. The curing environment temperature is controlled at 15-30℃ and the relative humidity is ≥90%. Natural curing is carried out for 7-14 days to continuously promote the secondary hydration reaction of the composite active solid waste admixture and the gradient expansion reaction of the dual-source expansion control components. This achieves a precise match between the hydration process and shrinkage compensation, and continuously inhibits the self-shrinkage of the gelation system. The fourth stage is the long-term stable curing stage. After the moist curing is completed, the surface covering material is removed, and curing continues in a natural ventilation environment until 28 days of age. The curing environment temperature is controlled at 5-35℃ and the relative humidity is ≥40%. This completes the gradient adaptation curing for the entire age period. No high-temperature steam curing is required throughout the process, which greatly reduces production energy consumption and carbon emissions.

[0011] As a further aspect of the present invention: Step seven specifically involves: after completing 28-day curing, conducting comprehensive performance testing and compliance verification on the finished bridge deck. The testing items include dimensional deviations, surface defects, mechanical properties, shrinkage performance, and durability. Specifically, dimensional deviations must meet the relevant requirements of GB / T51231 "Technical Standard for Prefabricated Concrete Buildings" and "Quality Inspection Standard for Precast Concrete Components." Mechanical property testing must ensure that the 28-day cubic compressive strength of the UHPC used in the bridge deck is ≥120MPa and the flexural strength is ≥18MPa. Shrinkage performance must meet the requirement of a 28-day self-shrinkage rate ≤150%. 60-day drying shrinkage ≤100 The durability performance must meet the requirement of electrical flux ≤100C. At the same time, the compressive strength, flexural strength and shrinkage rate test data of test blocks cured under the same conditions as the bridge deck at 24h, 7d, 14d and 28d are simultaneously verified. Only finished products that meet the preset qualified indicators for all test items can be issued a product qualification certificate and allowed to leave the factory. Finished products that do not meet the standards are strictly prohibited from entering the engineering application stage. This completes the entire preparation process of low shrinkage eco-friendly UHPC bridge deck.

[0012] In addition, this application also provides a low-shrinkage eco-friendly UHPC bridge panel, which is prepared by steps one to seven.

[0013] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows: 1. This invention addresses the core industry deficiency of existing eco-friendly UHPCs, which cannot simultaneously achieve high solid waste content and ultra-low shrinkage and crack resistance, through a material system design that incorporates gradient active solid waste compounding, dual-source expansion regulation, load-type internal curing, and three-level hybrid fiber synergy. It breaks the technical prejudice that large amounts of industrial solid waste inevitably lead to a surge in shrinkage and increased cracking risk. Through the synergistic effect of multiple components, it achieves stable regulation of the hydration process of the cementitious system throughout its entire life cycle and precise compensation for shrinkage deformation. While significantly improving the utilization rate of industrial solid waste and reducing cement usage, it inhibits the plastic shrinkage, autogenous shrinkage, and drying shrinkage of UHPC from the root of hydration, greatly reducing the cracking risk of bridge decks and significantly improving the long-term durability and service life of bridge decks. It achieves a synergistic unity between eco-friendly properties and structural crack resistance.

[0014] 2. This invention addresses the shortcomings of existing UHPC bridge deck structures, such as the disconnect between structural design and material shrinkage characteristics, the tendency to crack due to concentrated shrinkage stress, and the high energy consumption and high carbon emissions of the manufacturing process, by employing a gradient reinforcement structure design precisely adapted to the material shrinkage characteristics, a formwork-free recycled steel edging structure, a gradient mixing process matched to the hydration process of the cementitious system, and a full-age, steam-free gradient curing method. It achieves a precise match between material shrinkage characteristics and structural stress distribution, further enhancing crack resistance through stress release and constraint optimization at the structural end. At the same time, the full-process, high-temperature steam-free manufacturing process significantly reduces production energy consumption and carbon emissions, and the prefabricated integrated design also improves on-site construction and installation efficiency, achieving a balance of low carbonization, high stability, and high convenience throughout the entire life cycle of the bridge deck. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the method steps in an embodiment of the present invention. Detailed Implementation

[0016] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0017] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] Please see the appendix Figure 1 This invention discloses a method for preparing a low-shrinkage eco-friendly UHPC bridge panel, the method comprising the following steps: Step 1: Raw material pretreatment and precise weighing. The components of the composite active solid waste admixture are dried and ground separately. The composite active solid waste admixture includes steel slag powder, fly ash, slag, and silica fume. A gradient activity system is formed by controlling the specific surface area of ​​each component. Simultaneously, the pre-preparation of the loaded internal curing component is completed. Porous regenerated powder and superabsorbent resin are uniformly mixed in a certain proportion, pre-soaked in a saturated calcium hydroxide solution, filtered, and then air-dried until saturated. After clarifying the quality control indicators of each raw material, all raw materials are precisely weighed according to the preset formula. Step 2: Gradient dry mixing premixing process, which completes the dry mixing operation in two stages. First, the uniform stacking of gel powder and recycled fine aggregate is achieved, and then the three-dimensional uniform dispersion of composite mixed fibers is achieved to obtain dry mixing premix without component separation. Step 3: Gradient wet mixing plasticization process, which involves adding water and mixing in two stages. First, the matrix is ​​initially hydrated and uniformly plasticized, and then the load-bearing internal curing components are uniformly dispersed throughout the entire area to obtain a UHPC mixture with stable working performance. Step 4: Integrated mold assembly and steel reinforcement cage pre-embedding. Complete the mold assembly, precise positioning of the gradient reinforcement cage and various pre-embedded parts, and achieve formwork-free casting by using recycled steel edging. Step 5: Layered casting and high-frequency vibration. Layered casting is combined with high-frequency vibration to simultaneously mold the shrinkage stress release groove on the slab surface, thus completing the integrated casting and molding of the bridge deck. Step Six: Gradient-adaptive steam-free curing throughout the entire age period, divided into four stages precisely matched with the hydration process of the gelling system, to complete the entire process of steam-free, low-carbon curing and achieve full-cycle shrinkage inhibition; Step 7: Finished product performance testing and factory control. Conduct full performance testing and data verification on the finished products after maintenance. Products are allowed to leave the factory only after all indicators meet the standards.

[0019] Example 1 This embodiment provides a low-shrinkage eco-friendly UHPC bridge panel, the raw materials of which, by mass parts, are: 280 parts silicate cement, 520 parts composite active solid waste admixture, 10 parts nano-active modifier, 16 parts dual-source expansion regulating component, 8 parts load-type internal curing component, 18 parts polycarboxylate-based high-performance water-reducing agent, 140 parts mixing water, 130 parts composite mixed fiber, and 720 parts recycled fine aggregate.

[0020] The method for preparing the low-shrinkage eco-friendly UHPC bridge panel in this embodiment includes the following steps: Step 1: Raw material pretreatment and precise weighing. First, each component of the composite active solid waste admixture is dried and ground separately to control the specific surface area of ​​the steel slag powder to 450m². 2 / kg, Grade II fly ash specific surface area 550m² 2 / kg, specific surface area of ​​ultrafine slag and silica fume 750m² 2 / kg, forming a gradient active system; simultaneously complete the pre-preparation of the loaded internal maintenance component, mix the porous regenerated micro powder and superabsorbent resin at a mass ratio of 5.5:1, pre-soak in saturated calcium hydroxide solution for 2.5h, filter, and air dry at room temperature until saturated surface dry; After confirming that all raw material quality control indicators meet the requirements, accurately weigh all raw materials according to the above formula.

[0021] Step 2: Gradient dry mixing premixing process. Weighed silicate cement, composite active solid waste admixture, nano-active modifier, dual-source expansion control component, and recycled fine aggregate are put into a horizontal forced mixer at one time. The main shaft speed of the mixer is set to 50 r / min, and the first stage of dry mixing operation is started. The dry mixing time is 75s, so that all kinds of powders and recycled fine aggregates are fully mixed to form a continuous and compact particle gradation packing system. After the first stage of dry mixing is completed, the speed is kept constant, and the composite mixed fibers are evenly sprinkled into the mixing chamber in three batches. The second stage of dry mixing is started, and the dry mixing time is 45 seconds. This ensures that the three-level mixed fibers are uniformly dispersed in the powder skeleton in three dimensions, without fiber agglomeration or unidirectional orientation, thus producing a dry-mixed premix.

[0022] Step 3: Gradient wet mixing plasticizing process. Maintain the spindle speed of the horizontal forced mixer at 45 r / min. Add the pre-mixed polycarboxylate-based high-performance water-reducing agent and 112 parts of mixing water (80% of the total mixing water) to the dry-mixed premix at a uniform speed. Start the first stage of wet mixing operation. The wet mixing time is 105s. This allows the mixing liquid to fully contact and wet the powder skeleton, completing the initial hydration reaction of the cementitious material and uniform plasticizing of the matrix, and obtaining a matrix slurry with stable initial fluidity. After the first stage of wet mixing is completed, the rotation speed is kept constant. The remaining 20% ​​of the mixing water (28 parts) is mixed with the uniform suspension formed by the loading internal curing component and added to the matrix slurry at a uniform speed. The second stage of wet mixing is started and the wet mixing time is 75 seconds to ensure that the loading internal curing component is uniformly dispersed throughout the slurry. Finally, a low-shrinkage eco-friendly UHPC mixture with an extension of 660 mm, no segregation, and no bleeding is obtained.

[0023] Step 4: Integrated mold assembly and steel reinforcement cage pre-embedding. The steel mold is assembled and positioned on a horizontal prefabrication platform. A molded anti-slip patterned base film is pre-laid on the bottom surface of the inner side of the mold. After cleaning the debris and dust in the mold cavity, a special release agent is evenly applied to the inner wall of the mold and the surface of the base film. Then, the pre-welded asymmetric double-dimensional gradient reinforced steel reinforcement cage is smoothly hoisted into the mold cavity. The edge reinforcement zone of the steel reinforcement cage corresponds to the high-risk area of ​​shrinkage stress and the area of ​​concentrated negative bending moment in the bridge deck. The transition reinforcement zone corresponds to the transition area of ​​shrinkage stress and the transition area of ​​positive bending moment. The optimized reinforcement zone in the middle corresponds to the low-risk area of ​​shrinkage stress and the peak area of ​​positive bending moment. At the same time, the recycled steel U-shaped edging, hoisting straight thread sleeve, guardrail post pre-embedded hole, and pipeline reserved hole welded and fixed to the steel reinforcement cage are precisely positioned and installed. The inner side of the recycled steel edging is provided with a dovetail mechanical interlocking groove, which faces the inner cavity of the mold. The edging also serves as the side mold of the mold to achieve formwork-free casting. 18mm thick concrete protective layer spacers are evenly placed on the upper and lower layers of the steel reinforcement cage to ensure that the steel reinforcement cage is centered and the thickness deviation of the protective layer is controlled within ±2mm, thus completing the integrated assembly of the mold and the pre-embedded system.

[0024] Step 5: Layered Casting and High-Frequency Vibration. The prepared UHPC mixture is uniformly transported into the mold cavity through an integrated material receiving and spreading machine. Layered casting is carried out for full-section casting, with each layer being 45mm thick. Immediately after each layer is cast, an immersion-type high-frequency vibrator is used for vibration. The vibration frequency of the vibrator is 55Hz, and the vibration time at a single point is 25s. During the vibration process, the vibrator is vertically inserted 8mm into the lower layer of cast mixture to ensure tight bonding between layers, no blind spots in vibration, and no cold joints in construction. Vibration continues until there are no obvious large air bubbles overflowing from the surface of the mixture and no obvious sinking. Over-vibration is strictly prohibited throughout the process. After the full-section casting is completed, a mechanical scraper is used to initially level the slab surface. After standing for 45 minutes until the mixture initially sets, mechanical finishing and manual finishing are completed. At the same time, a special shaping mold is used to mold micro stress relief grooves perpendicular to the shrinkage stress direction on the slab surface. The stress relief grooves are 2.5mm deep, 6mm wide, and 250mm apart, completing the integrated casting and molding of the bridge deck.

[0025] Step Six: Full-Age Gradient Adaptation No-Steam Curing Immediately after casting and molding, the entire process of no-steam curing and low-carbon gradient curing begins, divided into four consecutive stages: First stage: Pre-condensation moisturizing care: After the surface is finished, immediately cover it with non-woven geotextile and sealing plastic film, control the curing environment temperature at 20±5℃ and relative humidity at ≥95%, and the curing time is 15 hours, and isolate the surface air flow throughout the process. Second stage: Curing at room temperature with mold: Maintain the curing environment temperature at 20±5℃ and relative humidity at ≥90%, continue curing in the mold for 30 hours until the compressive strength of the test block cured under the same conditions reaches 45MPa, and then remove the mold after completing the curing in the mold. The third stage, after demolding, involves hydration to promote moisturizing and nourishing: Immediately after demolding, water-based concrete curing agent is evenly sprayed onto the entire surface of the bridge deck at a rate of 0.4 kg / m². Then, non-woven geotextile and sealing plastic film are applied again. The curing environment temperature is controlled at 20±5℃ and the relative humidity is ≥90%. Natural curing is carried out for 10 days. Phase Four: Long-Term Stable Maintenance After the moisturizing and maintenance period ends, remove the surface covering material and continue maintenance in a naturally ventilated environment until 28 days of age. The temperature of the maintenance environment should be controlled at 10-30℃ and the relative humidity at ≥40% to complete the full-age maintenance.

[0026] Step 7: Finished Product Performance Testing and Factory Control. After completing the 28-day curing period, the bridge deck finished product undergoes full performance testing and compliance verification. The test data of test blocks under the same conditions at 24h, 7d, 14d, and 28d are also verified. The product is allowed to leave the factory after all indicators meet the standards.

[0027] Example 2 This embodiment provides a low-shrinkage eco-friendly UHPC bridge panel, the raw materials of which, by mass parts, are: 350 parts silicate cement, 450 parts composite active solid waste admixture, 15 parts nano-active modifier, 25 parts dual-source expansion regulating component, 12 parts load-type internal curing component, 25 parts polycarboxylate-based high-performance water-reducing agent, 160 parts mixing water, 160 parts composite mixed fiber, and 800 parts recycled fine aggregate.

[0028] The method for preparing the low-shrinkage eco-friendly UHPC bridge panel in this embodiment includes the following steps: Step 1: Raw material pretreatment and precise weighing. Each component of the composite activated solid waste admixture is dried and ground separately to control the specific surface area of ​​the steel slag powder to 500 m². 2 / kg, Grade II fly ash specific surface area 600m² 2 / kg, specific surface area of ​​ultrafine slag and silica fume 800m² 2 / kg, forming a gradient active system; simultaneously complete the pre-preparation of the loaded internal maintenance component, mix the porous regenerated micro powder and superabsorbent resin at a mass ratio of 6:1, pre-soak in saturated calcium hydroxide solution for 3h, filter, and air dry at room temperature until saturated surface dry state; After confirming that all raw material quality control indicators meet the requirements, accurately weigh all raw materials according to the above formula.

[0029] Step 2: Gradient dry mixing premixing process. Weighed silicate cement, composite active solid waste admixture, nano-active modifier, dual-source expansion control component, and recycled fine aggregate are put into a horizontal forced mixer at one time. The main shaft speed of the mixer is set to 55 r / min, and the first stage of dry mixing operation is started. The dry mixing time is 90s, so that all kinds of powders and recycled fine aggregates are fully mixed to form a continuous and compact particle gradation packing system. After the first stage of dry mixing is completed, the speed is kept constant, and the composite mixed fibers are sprinkled into the mixing chamber in three uniform portions. The second stage of dry mixing is then started, with a mixing time of 60 seconds, to ensure that the three-level mixed fibers are uniformly dispersed in the powder skeleton in three dimensions, without fiber agglomeration or unidirectional orientation, thus producing a dry-mixed premix.

[0030] Step 3: Gradient wet mixing plasticizing process. Maintain the spindle speed of the horizontal forced mixer at 50 r / min. Add the pre-mixed polycarboxylate-based high-performance water-reducing agent and 128 parts of mixing water (80% of the total mixing water) to the dry-mixed premix at a uniform speed. Start the first stage of wet mixing operation. The wet mixing time is 120s to allow the mixing liquid to fully contact and wet the powder skeleton, complete the initial hydration reaction of the cementitious material and uniform plasticization of the matrix, and obtain a matrix slurry with stable initial fluidity. After the first stage of wet mixing is completed, the rotation speed is kept constant. The remaining 20% ​​of the mixing water (32 parts) is mixed with the uniform suspension formed by the loading internal curing component and added to the matrix slurry at a uniform speed. The second stage of wet mixing is started and the wet mixing time is 90 seconds to ensure that the loading internal curing component is uniformly dispersed throughout the slurry. Finally, a low-shrinkage eco-friendly UHPC mixture with an extension of 690 mm, no segregation, and no bleeding is obtained.

[0031] Step 4: Integrated mold assembly and steel reinforcement cage pre-embedding. The steel mold is assembled and positioned on a horizontal prefabrication platform. A molded anti-slip patterned base film is pre-laid on the bottom surface of the inner side of the mold. After cleaning the debris and dust in the mold cavity, a special release agent is evenly applied to the inner wall of the mold and the surface of the base film. Then, the pre-welded asymmetric double-dimensional gradient reinforced steel reinforcement cage is smoothly hoisted into the mold cavity. The edge reinforcement zone of the steel reinforcement cage corresponds to the high-risk area of ​​shrinkage stress and the area of ​​concentrated negative bending moment in the bridge deck. The transition reinforcement zone corresponds to the transition area of ​​shrinkage stress and the transition area of ​​positive bending moment. The optimized reinforcement zone in the middle corresponds to the low-risk area of ​​shrinkage stress and the peak area of ​​positive bending moment. At the same time, the recycled steel U-shaped edging, hoisting straight thread sleeve, guardrail post pre-embedded hole, and pipeline reserved hole welded and fixed to the steel reinforcement cage are precisely positioned and installed. The inner side of the recycled steel edging is provided with a dovetail mechanical interlocking groove, which faces the inner cavity of the mold. The edging also serves as the side mold of the mold to achieve formwork-free casting. 20mm thick concrete protective layer spacers are evenly placed on the upper and lower layers of the steel reinforcement cage to ensure that the steel reinforcement cage is centered and the thickness deviation of the protective layer is controlled within ±2mm, thus completing the integrated assembly of the mold and the pre-embedded system.

[0032] Step 5: Layered Casting and High-Frequency Vibration. The prepared UHPC mixture is uniformly transported into the mold cavity through an integrated material receiving and spreading machine. Layered casting is carried out for full-section casting, with each layer being 50mm thick. After each layer is cast, an immersion-type high-frequency vibrator is immediately used for vibration. The vibration frequency of the vibrator is 60Hz, and the vibration time at a single point is 30s. During the vibration process, the vibrator is vertically inserted 10mm into the lower layer of cast mixture to ensure tight bonding between layers, no blind spots in vibration, and no cold joints in construction. Vibration continues until there are no obvious large air bubbles overflowing from the surface of the mixture and no obvious sinking. Over-vibration is strictly prohibited throughout the process. After the full-section casting is completed, a mechanical scraper is used to initially level the slab surface. After standing for 60 minutes until the mixture initially sets, mechanical finishing and manual finishing are completed. At the same time, a special shaping mold is used to mold micro stress relief grooves perpendicular to the shrinkage stress direction on the slab surface. The stress relief grooves are 3mm deep, 8mm wide, and 300mm apart, completing the integrated casting and molding of the bridge deck.

[0033] Step Six: Full-Age Gradient Adaptation No-Steam Curing Immediately after casting and molding, the entire process of no-steam curing and low-carbon gradient curing begins, divided into four consecutive stages: First stage: Pre-condensation moisturizing care: After the surface is finished, immediately cover it with non-woven geotextile and sealing plastic film, control the curing environment temperature at 20±5℃ and relative humidity at ≥95%, and the curing time is 18 hours, and isolate the surface air flow throughout the process. Second stage: Curing at room temperature with mold: Maintain the curing environment temperature at 20±5℃ and relative humidity at ≥90%, continue curing in the mold for 36 hours until the compressive strength of the test block cured under the same conditions reaches 48MPa, and then remove the mold after completing the curing in the mold. The third stage, after demolding, involves hydration to promote moisturizing and nourishing: Immediately after demolding, spray water-based concrete curing agent evenly on the entire surface of the bridge deck at a rate of 0.5 kg / m². Cover with non-woven geotextile and sealing plastic film again, and control the curing environment temperature at 15-30℃ and relative humidity at ≥90% for 14 days of natural curing. Phase Four: Long-Term Stable Maintenance After the moisturizing and maintenance period ends, remove the surface covering material and continue maintenance in a naturally ventilated environment until 28 days of age. The temperature of the maintenance environment should be controlled between 5-35℃ and the relative humidity ≥40% to complete the full-age maintenance.

[0034] Step 7, Finished Product Performance Testing and Factory Control, is the same as Step 7 in Example 1.

[0035] Comparative Example This comparative example is a conventional UHPC bridge deck. The comparative example adopts the typical technical solution of the current industry conventional UHPC bridge deck (high cement content cementitious system, quartz sand aggregate, single virgin steel fiber, conventional one-time mixing, equal strength reinforcement, high temperature steam curing). It should be noted that the comparison between the embodiment of the present invention and Comparative Example 1 is intended to demonstrate the comprehensive advantages of the material-structure-process whole chain synergistic solution over the existing conventional solution, and is not used to verify the independent effect of a certain technical means in isolation. The raw materials, by weight, are: 700 parts of P·O52.5 grade silicate cement, 80 parts of silica fume, 100 parts of grade 1 fly ash, 850 parts of quartz sand, 150 parts of virgin steel fiber, 20 parts of polycarboxylate-based high-performance water-reducing agent, and 150 parts of mixing water.

[0036] The preparation method of this comparative example adopts the industry-standard UHPC bridge panel preparation process, and the specific steps are as follows: 1. Weigh the cement, silica fume, fly ash, and quartz sand and put them into a horizontal forced mixer. Mix dry for 60 seconds to obtain a dry mixture. 2. Add the pre-mixed polycarboxylate-based high-performance water-reducing agent and all the mixing water, wet mix for 120 seconds to obtain the matrix slurry; 3. Add virgin steel fibers and continue wet mixing for 60 seconds to obtain the UHPC mixture; 4. Complete the assembly of conventional steel molds and the pre-embedding of ordinary equal-strength reinforced steel cages, and form them using conventional one-time casting and vibration operations; 5. Adopt the industry's conventional high-temperature steam curing process: After casting, cure at room temperature with the mold for 24 hours, then remove the mold and enter the steam curing kiln for 90℃ high-temperature steam curing for 48 hours, and then cure naturally for 28 days to complete the preparation.

[0037] Performance Testing and Results Analysis Test methods The performance tests of the embodiments and comparative examples of this invention were all performed in accordance with current national standards, as detailed below: Cube compressive strength and flexural strength: tested according to GB / T31387-2015 "Reactive Powder Concrete"; Self-shrinkage rate, drying shrinkage rate, and electrical flux: tested according to GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete"; Comprehensive utilization rate of industrial solid waste: calculated using the formula described above in this invention; Production energy consumption: calculated based on the combined electricity and heat consumption of the preparation process, in kWh / m³. 3 ; Surface crack condition: The surface of the bridge deck at 28 days of age was inspected in its entirety using a crack width observation instrument.

[0038] Test Result Comparison The core performance test results of Examples 1, 2, and the comparative examples are shown in Table 1 below:

[0039] Table 1: Core performance test results of Example 1, Example 2 and comparative examples Results Analysis The test results show that: Examples 1 and 2 of this invention are significantly superior to the comparative example in terms of comprehensive utilization rate of industrial solid waste, shrinkage performance, and production energy consumption. At the same time, their mechanical properties and durability also reach or exceed the level of conventional high-temperature steam-cured UHPC. 1. Significant ecological and environmental advantages: The comprehensive utilization rate of industrial solid waste in the embodiments of this invention reaches 58.2% and 52.7% respectively, which is much higher than the 8.7% of the comparative example. The amount of cement used is only 40%-50% of that in the comparative example, which greatly reduces the carbon emissions of cement production. 2. Significant improvement in shrinkage performance: The 28-day self-shrinkage rate and 60-day drying shrinkage rate of the embodiments of the present invention are far lower than those of the comparative example, and fully meet the ultra-low shrinkage index preset by the present invention. There are no visible cracks after 28 days of curing, which fundamentally solves the industry pain point of shrinkage cracking of UHPC bridge deck. 3. Outstanding advantages in low carbon and energy saving: This invention does not require high-temperature steam curing throughout the entire process, and the production energy consumption is only about 30% of the comparative ratio, which greatly reduces energy consumption and carbon emissions in the production process; 4. Excellent mechanical and durability properties: The compressive strength, flexural strength and electrical flux of the embodiments of the present invention are all better than or equal to those of the comparative examples, proving that the high strength and durability of UHPC can still be achieved under the conditions of no steam curing.

[0040] The aforementioned superior performance is the result of the synergistic innovation of the material system, process system and structural system of this invention. Among them, the gradient activated solid waste system and the full-age non-steam curing gradient maintenance process are the core technical support. The two, together with other technical means, have achieved the technical objectives of this invention.

[0041] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a low-shrinkage, eco-friendly UHPC bridge panel, characterized in that, The preparation method includes the following steps: Step 1: Raw material pretreatment and precise weighing. The components of the composite active solid waste admixture are dried and ground separately. The composite active solid waste admixture includes steel slag powder, fly ash, slag and silica fume. A gradient activity system is formed by controlling the specific surface area of ​​each component. Simultaneously, the pre-preparation of the loaded internal curing component is completed. The porous regenerated powder and superabsorbent resin are mixed evenly in proportion and then pre-soaked in a saturated calcium hydroxide solution. After filtration, the surface is air-dried to a saturated surface-dry state. After clarifying the quality control indicators of each raw material, all raw materials are precisely weighed according to the preset formula. Step 2: Gradient dry mixing premixing process, which completes the dry mixing operation in two stages. First, the uniform stacking of gel powder and recycled fine aggregate is achieved, and then the three-dimensional uniform dispersion of composite mixed fibers is achieved to obtain dry mixing premix without component separation. Step 3: Gradient wet mixing plasticization process, which involves adding water and mixing in two stages. First, the matrix is ​​initially hydrated and uniformly plasticized, and then the load-bearing internal curing components are uniformly dispersed throughout the entire area to obtain a UHPC mixture with stable working performance. Step 4: Integrated mold assembly and steel reinforcement cage pre-embedding. Complete the mold assembly, precise positioning of the gradient reinforcement cage and various pre-embedded parts, and achieve formwork-free casting by using recycled steel edging. Step 5: Layered casting and high-frequency vibration. Layered casting is combined with high-frequency vibration to simultaneously mold the shrinkage stress release groove on the slab surface, thus completing the integrated casting and molding of the bridge deck. Step Six: Gradient-adaptive steam-free curing throughout the entire age period, divided into four stages precisely matched with the hydration process of the gelling system, to complete the entire process of steam-free, low-carbon curing and achieve full-cycle shrinkage inhibition; Step 7: Finished product performance testing and factory control. Conduct full performance testing and data verification on the finished products after maintenance. Products are allowed to leave the factory only after all indicators meet the standards.

2. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 1, characterized in that: In step one, specifically: the specific surface area of ​​steel slag powder is controlled to be 400-500 m² / kg, the specific surface area of ​​fly ash is 500-600 m² / kg, and the specific surface area of ​​ultrafine slag and silica fume is 700-800 m² / kg, forming a gradient activity system of low, medium and high activity; the porous regenerated powder and superabsorbent resin are uniformly mixed at a mass ratio of 5-6:1, pre-soaked in a saturated calcium hydroxide solution for 2-3 hours, filtered, and then air-dried at room temperature under ventilation until saturated surface dry. The silicate cement is selected as P·O52.5 grade, the water reduction rate of the polycarboxylate-based high-performance water-reducing agent is ≥30%, the recycled fine aggregate is selected as either tailings sand or recycled concrete powder, the fineness modulus is controlled at 2.3-2.8, and the gradation is continuous. The composite mixed fiber is compounded according to the mass ratio of recycled steel fiber: high-strength polypropylene coarse fiber: polyvinyl alcohol micro fiber (60-70): (20-25): (5-15). The dual-source expansion control component is compounded according to the mass ratio of light-burned magnesium oxide expansion agent: ettringite type expansion agent (2-3):

1. According to the preset formula, weigh 200-350 parts of silicate cement, 450-600 parts of composite active solid waste admixture, 5-15 parts of nano-active modifier, 8-25 parts of dual-source expansion regulating component, 3-12 parts of load-type internal curing component, 10-25 parts of polycarboxylate-based high-performance water-reducing agent, 120-160 parts of mixing water, 100-160 parts of composite mixed fiber, and 650-800 parts of recycled fine aggregate to complete the raw material preparation before preparation.

3. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 2, characterized in that: In step two, the weighed silicate cement, composite active solid waste admixture, nano-active modifier, dual-source expansion control component, and recycled fine aggregate are put into a horizontal forced mixer at one time. The main shaft speed of the mixer is set to 45-55 r / min, and the first stage of dry mixing is started. The dry mixing time is strictly controlled within 60-90 seconds to fully mix the various powder materials with the recycled fine aggregate, forming a continuous and compact particle gradation packing system, and completing the pre-construction of the cementitious powder skeleton. After the first stage of dry mixing is completed, keep the mixer speed constant, and sprinkle the weighed composite mixed fibers into the mixer cavity in 2-3 times at a uniform speed. Start the second stage of dry mixing, and control the dry mixing time to 30-60 seconds. Finally, a dry premixed material with uniform dispersion and no component separation is obtained.

4. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 3, characterized in that: In step three, specifically: the main shaft speed of the horizontal forced mixer is kept at 40-50 r / min, and the pre-mixed polycarboxylate-based high-performance water-reducing agent and the mixing water accounting for 80% of the total mixing water are added at a uniform speed to the dry-mixed premix prepared in step two. The first stage of wet mixing operation is started, and the wet mixing time is controlled at 90-120s to complete the initial hydration reaction of the cementitious material and the uniform plasticization of the matrix, so as to obtain a matrix slurry with stable initial fluidity. After the first stage of wet mixing is completed, the mixer speed is kept constant. The remaining 20% ​​of the mixing water is mixed with the pre-prepared load-type internal curing component to form a uniform suspension, which is then added to the matrix slurry at a uniform speed. The second stage of wet mixing is then started. The wet mixing time is controlled at 60-90s. Finally, a low-shrinkage eco-friendly UHPC mixture with an expansion of 650±50mm, no segregation, no bleeding, and stable working performance is obtained.

5. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 4, characterized in that: Step four specifically involves: assembling and positioning the steel mold on a horizontal precast platform; pre-laying a molded anti-slip patterned base film on the inner bottom surface of the mold; cleaning debris and dust from the mold cavity; uniformly applying a special release agent to the inner wall of the mold and the surface of the base film; and then smoothly hoisting the pre-welded asymmetric double-dimensional gradient reinforced steel skeleton into the mold cavity. The edge reinforcement zone of the steel skeleton corresponds to the high-risk area of ​​shrinkage stress and the area of ​​negative bending moment concentration in the bridge deck, while the transition reinforcement zone corresponds to the transition area of ​​shrinkage stress and the transition area of ​​positive bending moment. In the central optimized reinforcement zone, corresponding to the low-risk area of ​​shrinkage stress and the peak area of ​​positive bending moment, the recycled steel U-shaped edging, hoisting straight thread sleeve, guardrail post pre-embedded holes, and pipeline reserved holes welded and fixed to the steel reinforcement skeleton are precisely positioned and installed simultaneously. The recycled steel edging is provided with a dovetail mechanical interlocking groove on the inner side, with the interlocking groove facing the inner cavity of the mold. Concrete protective layer spacers with a thickness of 15-20mm are evenly set on the upper and lower layers of the steel reinforcement skeleton, and the thickness deviation of the protective layer is controlled within ±2mm. Finally, the integrated assembly of the mold and the pre-embedded system is completed.

6. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 5, characterized in that: In step five, specifically: the low-shrinkage eco-friendly UHPC mixture obtained in step three is uniformly transported to the mold cavity assembled in step four through an integrated material receiving and spreading machine. The mixture is then poured in layers for the entire cross section. The thickness of each layer is strictly controlled to be 40-50mm. After each layer is poured, an immersion-type high-frequency vibrator is immediately used for vibration. The vibration frequency of the vibrator is controlled to be 50-60Hz, and the vibration time at a single point is controlled to be 20-30s. During the vibration process, the vibrator is vertically inserted into the lower layer of the mixture by 5-10mm. The mixture is vibrated until there are no obvious large air bubbles overflowing or obvious sinking on the surface of the mixture. After the full-section casting is completed, a mechanical scraper is used to initially level the slab surface. After standing for 30-60 minutes until the mixture initially sets, mechanical finishing and manual finishing are completed. At the same time, a special shaping mold is used to mold micro stress relief grooves perpendicular to the shrinkage stress direction on the slab surface. The stress relief grooves are 2-3mm deep, 5-8mm wide, and spaced 200-300mm apart, thus completing the integrated casting and molding of the bridge deck.

7. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 6, characterized in that: Step six specifically involves: immediately after casting and molding, entering a full-process, non-steam-curing, low-carbon gradient curing process. The curing process is divided into four continuous stages precisely adapted to the hydration process and expansion reaction rate of the cementitious system. The first stage is the pre-setting moisturizing curing stage, where non-woven geotextile and sealing plastic film are immediately covered on the finished bridge deck surface. The curing environment temperature is controlled at 20±5℃, the relative humidity is ≥95%, and the curing time is controlled at 12-18 hours. The entire process isolates the surface from air flow to prevent rapid surface moisture absorption. The first stage involves rapid evaporation to inhibit plastic shrinkage cracking at its source. The second stage is ambient temperature curing in formwork, maintaining an ambient temperature of 20±5℃ and relative humidity ≥90%, continuing curing in formwork for 24-36 hours until the compressive strength of the test blocks cured under the same conditions as the bridge deck reaches ≥40MPa. After completing the curing in formwork, the formwork is removed. The third stage is post-removal hydration-promoting and moisture-retaining curing. Immediately after removal from the formwork, a water-based concrete curing agent is evenly sprayed onto the entire surface of the bridge deck, with the spraying amount controlled at 0.3-0.5 kg / m². 2 Then, cover the surface with non-woven geotextile and sealing plastic film again, control the curing environment temperature at 15-30℃ and relative humidity ≥90%, and allow it to cure naturally for 7-14 days. This will continuously promote the secondary hydration reaction of the composite active solid waste admixture and the gradient expansion reaction of the dual-source expansion control components. The fourth stage is the long-term stable curing stage. After the moisturizing curing is completed, remove the surface covering material and continue curing in a natural ventilation environment until the age of 28 days. Control the curing environment temperature at 5-35℃ and relative humidity ≥40% to complete the full-age gradient adaptation curing.

8. The method for preparing a low-shrinkage eco-friendly UHPC bridge panel according to claim 7, characterized in that: Step seven specifically involves: after completing 28-day curing, conducting comprehensive performance testing and compliance verification on the finished bridge deck. Testing items include dimensional deviations, surface defects, mechanical properties, shrinkage performance, and durability. Dimensional deviations must meet relevant requirements. Mechanical property testing must ensure that the 28-day cubic compressive strength of the UHPC used in the bridge deck is ≥120MPa and the flexural strength is ≥18MPa. Shrinkage performance must meet the requirement of a 28-day self-shrinkage rate ≤150%. 60-day drying shrinkage ≤100 The durability performance must meet the requirement of electrical flux ≤100C. At the same time, the compressive strength, flexural strength and shrinkage rate test data of test blocks cured under the same conditions as the bridge deck at 24h, 7d, 14d and 28d are simultaneously verified. Only finished products that meet the preset qualified indicators for all test items can be issued a product qualification certificate and allowed to leave the factory. Finished products that do not meet the standards are strictly prohibited from entering the engineering application stage. This completes the entire preparation process of low shrinkage eco-friendly UHPC bridge deck.

9. The low-shrinkage eco-friendly UHPC bridge panel prepared by the preparation method according to any one of claims 1-8, characterized in that: The low-shrinkage eco-friendly UHPC bridge deck is prepared by steps one through seven.

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