Early strength concrete material for expansion joint anchoring area and preparation method of early strength concrete material

Abstract

The invention relates to an early strength concrete material for an expansion joint anchoring area and a preparation method thereof, and relates to the technical field of building materials, the early strength concrete material for the expansion joint anchoring area comprises the following components in parts by mass: gel master batch, coarse aggregate, fine aggregate, silica fume, mineral powder and a polycarboxylic acid water reducer; the gelling master batch is prepared from the following components in parts by mass: tricalcium silicate, anhydrous calcium sulphoaluminate, polyvinyl alcohol, polypropylene fiber and water; the preparation method comprises the steps of gelling master batch preparation, shearing and flaking, and mixing and forming. According to the early-strength concrete material for the expansion joint anchoring area and the preparation method of the early-strength concrete material, the concrete in the anchoring area is modified by using an organic matter as a crystal nucleus, so that a compact and ordered organic-inorganic cross-linked structure with a biomimetic structure is formed, and the early-strength performance and tensile toughness of the concrete are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to an early-strength concrete material for the anchorage zone of expansion joints and its preparation method. Background Technology

[0002] Expansion joints are key load-bearing components of transportation infrastructure such as bridges and roads. Their anchorage zones need to withstand repeated impacts, vibrations, and expansion and contraction caused by temperature changes from vehicle loads over a long period of time. Therefore, the lightweight concrete materials used in the anchorage zones must meet multiple performance requirements, such as early strength and rapid molding, high tensile strength, high toughness, and excellent impact resistance, in order to ensure the stability and service life of the anchorage structure.

[0003] However, traditional anchorage zone concrete has significant technical drawbacks under high loads and complex working conditions: First, ordinary concrete has low tensile strength, and concentrated loads transmitted from the anchorage are prone to transverse splitting stress, which can easily lead to cracking or even anchorage failure even with the addition of steel mesh; Second, early strength development is slow, which means that prestressing tensioning, rebar installation and other processes require a long curing period, thus restricting the construction progress; Third, the bond strength with the anchor depends on the physical bond of cement hydration products, which is easily weakened in harsh environments such as humidity and freeze-thaw cycles; Fourth, its mechanical properties are isotropic, which cannot directionally disperse local stress concentrations, and can easily cause the concrete below the anchorage to collapse.

[0004] To address the aforementioned issues, improvements have been made by incorporating mineral admixtures to optimize the microstructure, using water-reducing agents or expanding agents to improve construction and crack resistance, and adding fibers to enhance tensile strength. However, these solutions are mostly limited to optimizing a single performance and fail to systematically address the problem from the perspectives of process synergy and stress-oriented control.

[0005] Chinese invention patent application CN119683947A, published on March 25, 2025, discloses a polyvinyl alcohol fiber-reinforced concrete and its manufacturing method. The concrete components include a composite cement made of silicate cement, sand, silica fume, and fly ash, composite aggregate, polyvinyl alcohol fiber, modified water-reducing agent, modified reinforcing agent, self-healing capsule, and deionized water. It is prepared through a multi-step mixing, casting, and curing process. Through the synergistic effect of the components, the concrete improves compressive strength, flexural strength, and splitting tensile strength, ultimately enhancing the durability of the concrete.

[0006] In response to the above-mentioned technical solutions, the inventors discovered that composite cement includes multiple components such as silicate cement, sand, silica fume, and fly ash. The hydration characteristics of each component are very different, which can easily lead to high internal porosity and uneven structure. At the same time, the complex cement hydration products caused by multiple components can further interfere with the uniform bonding of the organic-inorganic interface, reduce the compactness of concrete, and thus reduce the strength of concrete. Summary of the Invention

[0007] In view of the shortcomings of traditional silicate cement and existing composite cement systems, and in order to meet the urgent need for early strength performance of concrete in the anchorage zone of expansion joints and further improve crack resistance and impact resistance, this invention provides an early strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0008] In a first aspect, the present invention provides an early-strength concrete material for the anchorage zone of expansion joints, employing the following technical solution: An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 200-250 parts of cementitious masterbatch, 400-450 parts of coarse aggregate, 200-250 parts of fine aggregate, 20-30 parts of silica fume, 30-60 parts of mineral powder, and 5-8 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 110-130 parts of tricalcium silicate, 60-75 parts of anhydrous calcium sulfoaluminate, 0.5-1.0 parts of polyvinyl alcohol, 1.5-4.0 parts of polypropylene fiber, and 28-40 parts of water.

[0009] By adopting the above technical solution, tricalcium silicate and anhydrous calcium sulfoaluminate in the gel masterbatch are rapidly hydrated to generate a large amount of CSH gel. A large number of hydroxyl groups on the polyvinyl alcohol molecular chain form stable hydrogen bonds with the active hydroxyl groups on the surface of CSH gel, constructing a strong organic-inorganic interface. At the same time, the polyvinyl alcohol molecular chain is uniformly embedded in the porous structure and micro-gaps of the CSH gel, playing a physical filling and bridging role and reducing internal defects of the gel. In addition, the hydrophilicity and film-forming properties of polyvinyl alcohol can promote the uniform dispersion and dense stacking of CSH gel particles, inhibit the disordered growth of the gel structure, and finally construct a uniform and stable organic-inorganic cross-linked crystal nucleus structure.

[0010] The macroscopic crack bridging effect of polypropylene fibers, the densification effect of silica fume, the synergistic effect of mineral powder, and the dispersion optimization of polycarboxylate superplasticizer improve the heterogeneity and brittleness of traditional concrete at the microstructural level, further enhancing the high toughness and impact resistance of concrete.

[0011] Optionally, the gel masterbatch further includes 0.4 to 1.2 parts of a silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite; wherein the mass ratio of silane coupling agent, tetrabutyl titanate, and polyethylene glycol is 0.4 to 0.6:1:2, and the molecular weight of the polyethylene glycol is 2000 to 4000; the preparation method of the silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite is as follows: Preparation of silane-modified tetrabutyl titanate: Tetrabutyl titanate was mixed with γ-aminopropyltriethoxysilane and stirred at 60°C and 500-600 r / min for 2-3 hours to obtain surface-silanized tetrabutyl titanate. Synthesis of ternary composite: Polyethylene glycol was dissolved by heating in a water bath at 40-50°C. The tetrabutyl silanized titanate was mixed with anhydrous ethanol at a volume ratio of 1:1 and then added to the polyethylene glycol solution. The mixture was stirred at 400 r / min for 30-60 min. Aging treatment: After sealing, age at 20-25℃ for 3-5 hours, then cool naturally to room temperature to obtain the product.

[0012] By adopting the above technical solution, the nano-titanium dioxide generated by the hydrolysis of tetrabutyl titanate serves as an inorganic crystal nucleus, guiding the directional growth of tricalcium silicate and anhydrous calcium sulfoaluminate hydration product CSH gel and optimizing its microstructure. Combined with the organic long chain of polyethylene glycol and polyvinyl alcohol to synergistically construct a cross-linking network, the deep organic modification of CSH gel is achieved, transforming the gelation system from a traditional loose stacking to a biomimetic dense cross-linked homogeneous structure.

[0013] Meanwhile, the silane coupling agent forms a chemical bond at one end through nano-titanium dioxide generated by the hydrolysis of amino groups and tetrabutyl titanate, as well as CSH gel, the hydration product of tricalcium silicate and anhydrous calcium sulfoaluminate. At the other end, it achieves physical entanglement and hydrogen bonding with organic phases such as polyvinyl alcohol and polyethylene glycol, as well as polypropylene fibers, through flexible segments. This reduces the interfacial voids between inorganic and organic components and between cementitious and fiber components in traditional concrete, allowing each component to form a tightly bonded homogeneous system. It strengthens the interfacial bond between the ternary composite and the hydration products of tricalcium silicate, anhydrous calcium sulfoaluminate, and polypropylene fibers. This not only improves the hardness and compressive strength of the concrete, but also significantly enhances its toughness through the synergistic effect of the flexible buffer of the organic phase and the rigid support of the inorganic crystal nuclei.

[0014] Optionally, the polyethylene glycol is carboxyl-modified polyethylene glycol; the preparation method of the carboxyl-modified polyethylene glycol is as follows: polyethylene glycol and maleic anhydride are mixed at a mass ratio of 10:1, and benzoyl peroxide is added at a mass ratio of 0.5 wt% of the total mass of polyethylene glycol and maleic anhydride. The mixture is reacted at 120-130°C for 4-6 hours, cooled, washed three times with anhydrous ethanol, and dried under vacuum at 60°C to obtain the final product.

[0015] By adopting the above technical solution, the carboxyl group reacts with the Ca in cement hydration products. 2+ It forms stable coordination bonds and can also form amide bonds with the amino groups of silane coupling agents. Compared with ordinary polyethylene glycol, which only relies on hydroxyl groups to form weak hydrogen bonds, it significantly improves the interfacial bonding strength between the ternary composite and the cement matrix and aggregates. The carboxyl groups form a chelate structure with Ti(OH)4 generated by the hydrolysis of tetrabutyl titanate, which slows down the hydrolysis rate of tetrabutyl titanate in the alkaline environment of concrete, avoids premature aggregation of nano-titanium dioxide, ensures its slow release and filling of cement pores, and continuously improves the density of concrete. In addition, after carboxyl modification, polyethylene glycol has better compatibility with polyvinyl alcohol and polypropylene fibers, forming a denser organic network, reducing micro-cracks inside concrete, and improving crack resistance and toughness.

[0016] Secondly, the present invention provides a method for preparing early-strength concrete material for the anchorage zone of expansion joints, employing the following technical solution: A method for preparing early-strength concrete material for the anchorage zone of expansion joints includes the following steps: S1: Preparation of gel masterbatch: including the preparation steps of viscous mixed slurry and the shearing and sheeting steps; Preparation of viscous mixed slurry: Weigh tricalcium silicate, anhydrous calcium sulfoaluminate, polyvinyl alcohol, and polypropylene fiber according to the mass fractions, dry mix for 3-5 minutes, add water, wet mix for 5-8 minutes to form a viscous mixed slurry with a viscosity of 10000-15000 mPa·s. Shearing and sheet preparation: The viscous mixed slurry is sheared using a two-roll mill to obtain continuous sheets with a thickness of 2-5 mm; S2: Mixing and molding: First, weigh out the coarse aggregate, fine aggregate, silica fume, and mineral powder according to the mass fraction, and dry mix for 3-5 minutes to ensure that the inorganic aggregate and mineral admixture are mixed evenly; then add the product prepared from the cementitious masterbatch, dry mix for 2-3 minutes, add 5-8 parts of polycarboxylate superplasticizer, and dry mix to obtain concrete premix.

[0017] By adopting the above technical solution, the two highly active early strength components, tricalcium silicate and anhydrous calcium sulfoaluminate, are first uniformly dispersed with polyvinyl alcohol and polypropylene fibers, and then wet-mixed to form a viscous slurry with a specific viscosity. This ensures the synergistic early strength effect of rapid hydration of tricalcium silicate to form CSH gel and simultaneous formation of ettringite by anhydrous calcium sulfoaluminate. At the same time, the polyvinyl alcohol molecular chains are uniformly embedded in the initial structure of CSH gel, and stable hydrogen bonds are formed between the hydroxyl groups and the hydroxyl groups on the gel surface, thus completing the directional modification of CSH gel. This transforms the gel itself from a traditional disordered and loose structure into a dense and ordered biomimetic crystal nucleus.

[0018] The shearing and sheeting process transforms viscous cementitious masterbatch into continuous sheets. On one hand, this eliminates the risk of polypropylene fiber agglomeration in the slurry, ensuring that the fibers are evenly distributed within the sheet. On the other hand, shearing force promotes the directional alignment of CSH gel crystal nuclei, forming an ordered structure similar to functional units in a biological organism, thus reducing performance fluctuations caused by local enrichment or absence of components in traditional concrete.

[0019] The mixing and molding process first allows coarse aggregate, fine aggregate, silica fume, and mineral powder to form a uniform and stable inorganic skeleton. Then, the cementitious masterbatch is incorporated as a functional unit containing CSH-modified crystal nuclei. Finally, the interfacial compatibility is optimized by using a polycarboxylate superplasticizer, so that the cementitious masterbatch and the inorganic skeleton are tightly bonded. At the same time, the ordered structure disperses the impact load, avoiding damage caused by local stress concentration.

[0020] Optionally, in the shearing and sheeting step, biodegradable polylactic acid microspheres are added to the viscous mixed slurry, stirred evenly, and then sheared; the amount of polylactic acid microspheres added accounts for 0.7 to 1.0 wt% of the mass of the viscous mixed slurry.

[0021] By adopting the above technical solution, polylactic acid microspheres, as uniformly dispersed organic phase micro-units, can optimize the rheological properties of the system during slurry shearing, promote the uniform distribution of polyvinyl alcohol molecules, provide more crystal nucleus growth sites for CSH gel, and help form a more uniform, dense, and organically flexible modified CSH gel network, significantly reducing the heterogeneity inside concrete and improving tensile strength. On the other hand, when subjected to stress, these microspheres can absorb impact energy through elastic deformation and interfacial debonding, making up for the shortcomings of traditional concrete in lacking effective energy dissipation, and greatly improving the toughness and impact resistance of the material. At the same time, the biodegradable properties of polylactic acid allow it to slowly degrade in the later stage of cement hydration to form micropores, which can not only release the internal stress generated during hydration and avoid early cracking caused by stress concentration, but also further enhance the organic-inorganic synergistic bonding effect through the interfacial interaction between degradation products and cement hydration products, thereby achieving the goal of high toughness and impact resistance of concrete in the anchoring zone.

[0022] Optionally, step S1 further includes a modification step, which is performed after the shearing and sheet-making step; the modification step is as follows: immersing the sheet in an epoxy resin solution for 30-50 seconds, filtering and drying to form a uniform modified film on the sheet surface; the mass ratio of bisphenol A epoxy resin, diethylenetriamine, and anhydrous ethanol in the epoxy resin solution is 1:0.1-0.15:7-8.

[0023] By adopting the above technical solution, the sheet formed after shearing is rich in CSH gel generated by the hydration of tricalcium silicate and anhydrous calcium sulfoaluminate. Immersion allows epoxy resin to quickly penetrate into the pores inside the sheet with the help of anhydrous ethanol and form hydrogen bonds with the hydroxyl groups on the surface of CSH gel. At the same time, diethylenetriamine acts as a curing agent to promote the formation of a uniform and dense modified film of epoxy resin on the surface and inside the sheet. When mixed with concrete premix, it can efficiently induce the surrounding cementitious materials to directionally hydrate and generate more CSH gel with a uniform structure, thereby achieving overall structural homogenization.

[0024] Meanwhile, the epoxy resin modified film has both high adhesion and high toughness. It can fill the micropores of CSH gel to improve the hardness and strength of the material, and can also absorb energy and prevent the propagation of microcracks through bridging effect when concrete is subjected to tensile or impact stress. It forms a dual organic modification synergy with the polyvinyl alcohol in the original sheet, reducing the phenomenon of high brittleness of concrete under high strength.

[0025] Optionally, step S1 further includes a pre-impregnation step, which is set after the modification step; the pre-impregnation step is as follows: the epoxy resin modified gel masterbatch sheet is cut into square fragments, pre-impregnated in water at 30-40°C for 2-3 minutes, removed and drained to obtain pre-impregnated sheet fragments; the amount of water used is 10-15 wt% of the sheet material weight.

[0026] By adopting the above technical solution, pre-impregnation forms a uniform water film on the surface of the epoxy resin modified cementitious masterbatch sheet, avoiding local moisture imbalance caused by excessive water absorption during subsequent mixing with the concrete matrix. This ensures the uniformity of CSH gel formation and activates the active sites on the sheet surface through gentle hydration. This allows the organic phase interface of the epoxy resin modified with the polyvinyl alcohol modified CSH gel to form a stronger organic-inorganic cross-linking network, filling the weak interfacial area between aggregate and cementitious matrix in traditional concrete and reducing material heterogeneity. At the same time, after pre-impregnation, tiny CSH gel nuclei will form on the surface of the sheet fragments in advance, inducing the directional growth of CSH gel in the concrete matrix, promoting a denser and more ordered gel structure, and avoiding the brittleness problem caused by the disordered accumulation of CSH gel in traditional concrete.

[0027] Optionally, in step S2, steel fibers are added at a total mass of 0.2 to 0.3 wt% of the dry mix and the gelling masterbatch sheet.

[0028] By adopting the above technical solutions, the high-strength CSH gel skeleton formed by the hydration of steel fibers and tricalcium silicate, the micro-density of the gel brought about by polyvinyl alcohol modification, and the micro-crack bridging function of polypropylene fibers complement each other. On the one hand, it inhibits the initiation and propagation of cracks in the expansion joint anchorage zone caused by repeated expansion and contraction deformation and concentrated impact loads, thus solving the industry pain point of the brittleness of early-strength concrete. On the other hand, the mechanical interlocking force and interfacial chemical bonding between steel fibers and concrete matrix not only significantly improve the tensile strength, flexural toughness and impact resistance of concrete, but also strengthen the interfacial synergistic bearing capacity between concrete and anchorage steel / structure, reducing the risk of performance degradation under repeated loading.

[0029] Optionally, in step S2, 0.1–0.2 wt% of silane coupling agent-modified calcium carbonate is added, comprising the total mass of the dry mix and the gelling masterbatch sheet, wherein the mass ratio of silane coupling agent to calcium carbonate is 1:100–200; the preparation method of the silane coupling agent-modified calcium carbonate is as follows: Stir calcium carbonate at 60–80°C and 800–1000 r / min for 10–15 min; spray γ-aminopropyltriethoxysilane evenly and continue stirring for 30–40 min; lower the temperature to 40–50°C and stir for 20–30 min; cool to room temperature and pass through a 200-mesh sieve to remove agglomerated particles to obtain the final product.

[0030] By adopting the above technical solution, the ethoxy group at one end of the γ-aminopropyltriethoxysilane molecule can form stable covalent bonds with the hydroxyl groups on the surface of calcium carbonate, the active sites of CSH gel, and the surface of aggregate. The amino group at the other end can form hydrogen bonds or chemical adsorption with the hydroxyl groups of polyvinyl alcohol molecular chains and the surface of polypropylene fibers. This is equivalent to building a bridging structure between the inorganic and organic phases, significantly reducing the interfacial porosity, improving the bonding strength of each component, and solving the defects of poor compatibility of organic-inorganic interfaces and easy stress concentration in traditional systems. At the same time, the modified calcium carbonate particles have improved dispersibility and can be embedded in the capillary pores of concrete as a nanoscale filling phase to further densify the microstructure, reduce water penetration channels, and take into account both early strength performance and impermeability and erosion resistance.

[0031] In addition, this addition time avoids the rapid hydration process of tricalcium silicate and anhydrous calcium sulfoaluminate during the preparation stage of the cementitious masterbatch, thus preventing the silane coupling agent from reacting prematurely with highly active minerals and losing its interfacial coupling function, or from calcium carbonate agglomerating due to the state of the cementitious masterbatch slurry. This ensures that the modified calcium carbonate is uniformly dispersed in the overall system, ultimately achieving a synergistic improvement in the early strength, toughness, and durability of concrete.

[0032] Thirdly, the present invention provides a method for using early-strength concrete material in the anchorage zone of expansion joints, wherein the premixed concrete prepared in step S2 is mixed with 80-100 parts of water on site according to the mass of the premixed concrete, stirred evenly, and then cured.

[0033] In summary, the present invention has at least one of the following beneficial technical effects: 1. A large amount of CSH gel is generated by the rapid hydration of tricalcium silicate and anhydrous calcium sulfoaluminate. The hydrophilicity and film-forming properties of polyvinyl alcohol can promote the uniform dispersion and dense stacking of CSH gel particles, inhibit the disordered growth of gel structure, and finally construct a uniform and stable organic-inorganic cross-linked crystal nucleus structure, which significantly improves tensile strength and toughness.

[0034] 2. By encapsulating the tetrabutyl titanate-polyethylene glycol ternary complex with silane to form a synergistic effect, nano-titanium dioxide further guides the directional growth of the gel, constructing a dense and ordered biomimetic crystal nucleus structure. At the same time, the organic long chains of polyethylene glycol and polyvinyl alcohol are combined to synergistically construct a cross-linking network, achieving deep organic modification of CSH gel and forming a denser cross-linked homogeneous structure.

[0035] 3. By reducing polypropylene fiber agglomeration through shearing sheeting, CSH gel nuclei are oriented and aligned. Combined with the rheological regulation of polylactic acid microspheres, the heterogeneity inside the concrete is significantly reduced. Epoxy resin modification and pre-impregnation steps form a dual interface optimization, which not only allows the sheet to be tightly bonded to the inorganic skeleton, but also induces homogeneous gel growth through pre-activated active sites, avoiding the local enrichment of components caused by traditional mixing processes, and constructing a homogeneous system that balances strength and toughness.

[0036] 4. The sealing effect of the epoxy resin modified film reduces the interfacial porosity; the micro-filling of modified calcium carbonate and the internal stress release function of biodegradable microspheres reduce water penetration channels and alleviate hydration internal stress, thereby improving the impermeability and erosion resistance of concrete and extending the service life of concrete in the anchorage zone. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments.

[0038] Example 1: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0039] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 200 parts of cementitious masterbatch, 400 parts of coarse aggregate, 200 parts of fine aggregate, 20 parts of silica fume, 30 parts of mineral powder, and 5 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 110 parts of tricalcium silicate, 60 parts of anhydrous calcium sulfoaluminate, 0.5 parts of polyvinyl alcohol, 1.5 parts of polypropylene fiber, and 28 parts of water.

[0040] The requirements for the above materials are as follows: ① Tricalcium silicate: purity ≥95%, free calcium oxide ≤1.0%, moisture content ≤0.5%; ② Anhydrous calcium sulfoaluminate: purity ≥90%, free calcium oxide ≤0.8%; ③ Polyvinyl alcohol: degree of polymerization 1850±150, purity ≥98%, 80 mesh passing rate ≥95%; ④ Polypropylene fiber: length 9±3mm, diameter 30±10μm, elongation at break 20±5%; ⑤ Water: pH value 7.5±1.0, chloride ion concentration ≤50mg / L, SO42- ≤10 ... 2- Concentration ≤200mg / L; ⑥ In this embodiment, the coarse aggregate is crushed stone with a particle size of 15±10mm; ⑦ In this embodiment, the fine aggregate is medium sand with a fineness modulus of 2.6±0.4; ⑧ In this embodiment, the silica fume is micro silica powder with a SiO2 content ≥90% and a moisture content ≤2.0%; ⑨ In this embodiment, the mineral powder is granulated blast furnace slag powder, grade S95; ⑩ The polycarboxylic acid water-reducing agent can be selected from one or more combinations of methoxy polyethylene glycol methacrylate copolymer, olefin and unsaturated carboxylic acid and their ester copolymers, and acrylic acid-hydroxyethyl acrylate copolymer. In this embodiment, methoxy polyethylene glycol methacrylate copolymer is selected.

[0041] The preparation method is as follows: S1: Preparation of gel masterbatch: including the preparation steps of viscous mixed slurry and the shearing and sheeting steps; Preparation of viscous mixed slurry: Weigh tricalcium silicate, anhydrous calcium sulfoaluminate, polyvinyl alcohol, and polypropylene fiber according to the mass fractions, put them into a mixer, stir at 350 r / min, dry mix for 3-5 min, add water, adjust the stirring speed to 480 r / min, wet mix for 6.5 min, to form a viscous mixed slurry with a viscosity of 12500 mPa·s; Shearing and sheet production: Start the twin-roll mill, preheat the rollers to 35°C, adjust the initial value of the twin-roll gap to 8mm, and feed the viscous mixed slurry into the gap of the twin rollers at a uniform speed to shear and crush the slurry. The twin-roll speed is set to 20r / min for the front roller and 25r / min for the rear roller to obtain continuous sheets. The thickness of the sheets is stable at 3.5±1.5mm. The sheets are conveyed to the collection area by a conveyor belt and naturally cooled to room temperature. S2: Mixing and molding: First, weigh out the coarse aggregate, fine aggregate, silica fume, and mineral powder according to the mass fractions, put them into the mixer, set the mixing speed to 225 r / min and dry mix for 4 min; then add the sheet material prepared from the cementitious masterbatch into the mixer, maintain the speed and dry mix for 2.5 min, add 6.5 parts of polycarboxylate superplasticizer, and after an interval of 1 min, evenly sprinkle it into the mixer in 2 batches, and continue to dry mix for 2.5 min to obtain the concrete premix.

[0042] The method of using the prepared early-strength concrete material for the expansion joint anchorage zone is as follows: The premixed concrete obtained in the above mixing and molding step is mixed with 90 parts of water on site according to the mass of the premixed concrete. The mixing speed is 325 r / min for 4 minutes. After mixing evenly, it is immediately poured into the mold of the expansion joint anchoring area. After molding, it is cured by covering it with geotextile to keep it moist. It is then placed under the conditions of ambient temperature of 20±5℃ and relative humidity ≥90% for curing. During the curing period, it is sprayed with water twice a day. It can be put into use after curing to the specified age.

[0043] Testing indicators: 1-day compressive strength, 3-day compressive strength, 28-day compressive strength, 28-day flexural strength, and slump of fresh concrete.

[0044] Flexural strength & compressive strength: Tested according to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" to verify the strength effect.

[0045] Compressive strength (MPa): Tested after 1 day, 3 days and 28 days of standard curing, with 3 samples in each group and the average value was taken; Flexural strength (MPa): Tested after 28 days of standard curing, with 3 samples in each group and the average value was taken.

[0046] The slump of fresh concrete (mm) was tested according to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" to verify the workability after on-site mixing and ensure that it can be poured and vibrated. The test was conducted after adding water and mixing on-site, with 3 samples in each group and the average value was taken.

[0047] Example 2: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0048] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 250 parts of cementitious masterbatch, 450 parts of coarse aggregate, 250 parts of fine aggregate, 30 parts of silica fume, 60 parts of mineral powder, and 8 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 130 parts of tricalcium silicate, 75 parts of anhydrous calcium sulfoaluminate, 1.0 part of polyvinyl alcohol, 4.0 parts of polypropylene fiber, and 40 parts of water.

[0049] Everything else is exactly the same as in Example 1.

[0050] Example 3: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0051] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 225 parts of cementitious masterbatch, 425 parts of coarse aggregate, 225 parts of fine aggregate, 25 parts of silica fume, 45 parts of mineral powder, and 6.5 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 120 parts of tricalcium silicate, 67.5 parts of anhydrous calcium sulfoaluminate, 0.75 parts of polyvinyl alcohol, 2.7 parts of polypropylene fiber, and 34 parts of water.

[0052] Everything else is exactly the same as in Example 1.

[0053] The early-strength concrete material used in the expansion joint anchorage zone prepared in Examples 1-3 was tested, and the test results are shown in Table 1: Table 1: Indicator Name Example 1 Example 2 Example 3 1-day compressive strength (MPa) 7.2 7.5 7.9 3D compressive strength (MPa) 17.5 18.8 19.5 28-day compressive strength (MPa) 37.8 39.5 41.2 28-day flexural strength (MPa) 4.5 4.4 4.6 Slump of freshly mixed concrete (mm) 181 189 185 Data from Examples 1, 2, and 3 show that, in terms of strength, Example 3 exhibits the strongest synergistic effect due to the superior strength of its mix proportions, resulting in a higher strength than Examples 1 and 2. Regarding workability, the slump of the freshly mixed concrete shows a positive correlation with the amount of cementitious masterbatch. Overall, the early-strength concrete materials prepared in the three examples for the expansion joint anchorage zone meet the requirements of the expansion joint anchorage zone in terms of early strength, mechanical strength, toughness, and workability, thus verifying the rationality of the basic formula range of this invention.

[0054] Example 4: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0055] In this embodiment, the gel masterbatch also includes 0.8 parts of a silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite; wherein the mass ratio of silane coupling agent, tetrabutyl titanate, and polyethylene glycol is 0.5:1:2, and the molecular weight of the polyethylene glycol is 3000±1000; the preparation method of the silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite is as follows: Preparation of silane-modified tetrabutyl titanate: Tetrabutyl titanate was mixed with γ-aminopropyltriethoxysilane and stirred at 60°C and 550 r / min for 2.5 hours to obtain a uniform pale yellow surface-silanized tetrabutyl titanate. Ternary compound synthesis: Polyethylene glycol was dissolved by heating in a water bath at 45°C. Tetrabutyl silanized titanate and anhydrous ethanol were mixed at a volume ratio of 1:1 to prepare a premixed solution, which was then added to the polyethylene glycol solution and stirred at 400 r / min for 45 min to form a homogeneous, particle-free viscous liquid. Aging treatment: Transfer the above viscous liquid to a sealed device and seal it. Place it in an environment of 22.5±2.5℃ and avoid light for 4 hours. After aging, remove it and let it cool naturally to room temperature. Seal it and store it in the dark for later use.

[0056] Everything else is exactly the same as in Example 3.

[0057] Example 5: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0058] In this embodiment, the polyethylene glycol in the silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite is carboxyl-modified polyethylene glycol. The preparation method of the carboxyl-modified polyethylene glycol is as follows: polyethylene glycol and maleic anhydride are mixed at a mass ratio of 10:1, and benzoyl peroxide is added at a mass ratio of 0.5 wt% of the total mass of polyethylene glycol and maleic anhydride. The mixture is reacted at 125°C for 5 hours, cooled, washed three times with anhydrous ethanol, and dried under vacuum at 60°C to obtain the final product.

[0059] Everything else is exactly the same as in Example 4.

[0060] Example 6: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0061] In this embodiment, during the shearing and sheeting step of the method for preparing early-strength concrete material for the expansion joint anchorage zone, biodegradable polylactic acid microspheres are added to the viscous mixed slurry, stirred evenly, and then sheared; wherein the amount of polylactic acid microspheres added accounts for 0.85 wt% of the mass of the viscous mixed slurry.

[0062] Everything else is exactly the same as in Example 5.

[0063] The early-strength concrete material used in the expansion joint anchorage zone prepared in Examples 4-6 was tested, and the test results are shown in Table 2: Table 2: Indicator Name Example 4 Example 5 Example 6 1-day compressive strength (MPa) 8.1 9.2 9.2 3D compressive strength (MPa) 21.3 24.6 25.1 28-day compressive strength (MPa) 43.8 47.5 48.2 28-day flexural strength (MPa) 4.6 4.9 5.2 Slump of freshly mixed concrete (mm) 195 200 202 By comparing Example 4 with Example 3, it can be seen that the addition of silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite in the cementitious masterbatch of Example 4 significantly reduces the porosity at the organic-inorganic interface, thus enabling the components to bind tightly and improving the early strength and long-term compressive strength of concrete. This demonstrates the continuous promoting effect of crystal nuclei on the hydration process. In addition, the optimization of the system's dispersion improves the workability of concrete, further illustrating the synergistic enhancing effect of the ternary composite on the early strength, structural density, and construction adaptability of concrete without affecting toughness.

[0064] A comparison of Example 5 and Example 4 shows that in Example 5, replacing the ordinary polyethylene glycol in the silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite with carboxyl-modified polyethylene glycol resulted in superior performance across all indicators compared to Example 4. The reason for this is attributed to the interaction between the carboxyl groups on the molecular chain and the Ca groups in the cement hydration products. 2+ It forms stable coordination bonds and amide bonds with the amino group of the silane coupling agent, which greatly enhances the interfacial bonding strength between the ternary composite and the cement matrix, aggregate and organic phase. On the other hand, the carboxyl group can form a chelate structure with Ti(OH)4 generated by the hydrolysis of tetrabutyl titanate, which slows down its hydrolysis rate in the alkaline environment of concrete, avoids premature aggregation of nano titanium dioxide, ensures its slow release and filling of cement pores, and continuously improves the density of concrete.

[0065] Comparing Example 6 with Example 5, it can be seen that the polylactic acid microspheres added in Example 6 do not directly participate in the hydration reaction of tricalcium silicate and anhydrous calcium sulfoaluminate, and therefore have no significant effect on the 1-day early strength performance. However, as uniformly dispersed organic phase micro-units, they can optimize the rheological properties of the system during shearing and sheeting, reduce polyvinyl alcohol molecular aggregation, provide more crystal nucleus growth sites for CSH gel, promote the uniform and dense formation of gel network, and thus slightly improve the 3-day and 28-day compressive strength. At the same time, when subjected to stress, polylactic acid microspheres can absorb impact energy through elastic deformation and interfacial debonding, making up for the lack of an effective energy dissipation mechanism in traditional early strength concrete, thereby improving the flexural strength. In addition, the dispersion effect of microspheres can also slightly optimize the fluidity of concrete mixture, resulting in a slight increase in slump.

[0066] Example 7: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0067] This embodiment adds a modification step to the preparation method. The modification step is performed after the shearing and slide preparation step. Specifically, the modification step is as follows: First, bisphenol A epoxy resin, diethylenetriamine, and anhydrous ethanol are mixed and stirred at a mass ratio of 1:0.12:7.5 until completely dissolved to prepare a uniform epoxy resin solution. The sheet obtained by shearing is completely immersed in the epoxy resin solution for 40 seconds, ensuring that the sheet is completely submerged and does not float. After immersion, excess solution is quickly filtered off using a vacuum filtration method. Then, it is placed in a 45°C constant temperature drying oven for 30 minutes to ensure that a uniform, bubble-free modified film is formed on the surface of the sheet. After drying, it is ready for use.

[0068] Everything else is exactly the same as in Example 5.

[0069] Example 8: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0070] In this embodiment S1, the preparation step of the gel masterbatch also includes a pre-impregnation step, which is set after the modification step; the pre-impregnation step is as follows: the epoxy resin modified gel masterbatch sheet is cut into 20mm×20mm square fragments, pre-impregnated in water at 35°C for 2.5min, taken out and drained to obtain pre-impregnated sheet fragments; the amount of water used is 12.5wt% of the sheet material weight.

[0071] Everything else is exactly the same as in Example 7.

[0072] Example 9: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0073] In the mixing and molding step of this embodiment, steel fibers accounting for 0.25 wt% of the total mass of the dry mix and the gel masterbatch sheet are added.

[0074] Everything else is exactly the same as in Example 8.

[0075] Example 10: This example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0076] In the mixing and molding step, 0.15 wt% of silane coupling agent modified calcium carbonate is added, comprising the total mass of the dry mix and the gel masterbatch sheet, wherein the mass ratio of silane coupling agent to calcium carbonate is 1:150; the preparation method of the silane coupling agent modified calcium carbonate is as follows: Calcium carbonate was stirred at 70℃ and 900 r / min for 12.5 min; γ-aminopropyltriethoxysilane was sprayed evenly and stirred for another 35 min; the temperature was lowered to 45℃ and stirred for 25 min; after cooling to room temperature, it was passed through a 200-mesh sieve to remove agglomerated particles, and the product was obtained.

[0077] Everything else is exactly the same as in Example 9.

[0078] The early-strength concrete material used in the expansion joint anchorage zone prepared in Examples 7-10 was tested, and the test results are shown in Table 3: Table 3: Indicator Name Example 7 Example 8 Example 9 Example 10 1-day compressive strength (MPa) 9.4 9.5 9.8 9.9 3D compressive strength (MPa) 26.3 27.5 28.8 28.9 28-day compressive strength (MPa) 49.6 50.8 52.3 53.1 28-day flexural strength (MPa) 5.0 5.3 5.8 5.7 Slump of freshly mixed concrete (mm) 201 205 202 210 By comparing Example 7 with Example 5, it can be seen that epoxy resin forms a uniform modified film on the surface of the gel masterbatch sheet. On the one hand, it combines with the hydroxyl groups on the surface of CSH gel through hydrogen bonds, filling the micropores to achieve structural densification. On the other hand, the cured epoxy film has both high adhesion and toughness, and inhibits the propagation of microcracks through the bridging effect. Therefore, early strength performance and workability are optimized simultaneously.

[0079] Furthermore, Examples 6 and 7 were not selected simultaneously because polylactic acid microspheres need to be uniformly dispersed in a viscous slurry to provide uniform growth sites for CSH gel, while epoxy resin modification requires the formation of a continuous and dense modified film on the surface of the sheet after shearing. If both are used simultaneously, the polylactic acid microspheres dispersed inside the sheet will hinder the penetration and film formation of the epoxy resin solution, leading to defects such as pores and fractures in the modified film, weakening its interface strengthening and crack prevention functions. At the same time, there is a contradiction in stress transmission between the organic flexible phase of polylactic acid microspheres and the rigid epoxy resin film after curing, which disrupts the organic-inorganic ratio balance inside the concrete, resulting in a decrease in structural density.

[0080] Comparing Example 8 with Example 7, it can be seen that Example 8 adds a pre-impregnation step of the cementitious masterbatch sheet after epoxy resin modification. This not only avoids local moisture imbalance caused by the sheet absorbing water too quickly during subsequent mixing with the concrete matrix, but also strengthens the organic-inorganic crosslinking effect of epoxy resin modification by activating the active hydroxyl sites on the sheet surface, filling the weak interface area between aggregate and cementitious matrix in traditional concrete. At the same time, the micro CSH gel nuclei formed in advance on the surface of the pre-impregnated sheet fragments can induce the directional growth of CSH gel in the concrete matrix, promoting a denser and more ordered gel structure and avoiding the brittleness problem caused by disordered accumulation. Therefore, all indicators are improved.

[0081] Comparing Example 9 with Example 8, it can be seen that the introduction of steel fibers improves the strength of concrete, but the slump of the fresh concrete decreases slightly. This is because although steel fibers do not directly participate in the cement hydration process, the mechanical interlocking force and interfacial chemical bonding between them and the concrete matrix significantly improve the flexural strength, a toughness index of the concrete. The slight decrease in slump is due to the fact that steel fibers are rigid fibers and are prone to slight agglomeration during mixing, which slightly interferes with the fluidity of the system, but does not affect the overall construction and pouring performance.

[0082] By comparing Example 10 with Example 9, it can be seen that the 1d, 3d and 28d compressive strength of Example 10 are slightly higher than those of Example 9. At the same time, the dispersibility of modified calcium carbonate after modification with silane coupling agent is significantly optimized, avoiding the impact of agglomeration on fluidity, and the slump of fresh concrete is greatly improved.

[0083] Comparative Example 1: This comparative example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0084] An early-strength concrete material for the anchorage zone of expansion joints comprises the following components by mass: silicate cement, 425 parts coarse aggregate, 225 parts fine aggregate, 25 parts silica fume, 45 parts mineral powder, and 6.5 parts polycarboxylate superplasticizer; wherein the silicate cement is P.O42.5 silicate cement.

[0085] In this example, the preparation and application methods of the early-strength concrete material used in the expansion joint anchorage zone are exactly the same as in Example 3.

[0086] Comparative Example 2: This comparative example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0087] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 199.5 parts of cementitious masterbatch, 400 parts of coarse aggregate, 200 parts of fine aggregate, 20 parts of silica fume, 30 parts of mineral powder, and 5 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 110 parts of tricalcium silicate, 60 parts of anhydrous calcium sulfoaluminate, 1.5 parts of polypropylene fiber, and 28 parts of water.

[0088] Everything else is exactly the same as in Example 3.

[0089] Comparative Example 3: This comparative example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0090] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 198.5 parts of cementitious masterbatch, 400 parts of coarse aggregate, 200 parts of fine aggregate, 20 parts of silica fume, 30 parts of mineral powder, and 5 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 110 parts of tricalcium silicate, 60 parts of anhydrous calcium sulfoaluminate, 0.5 parts of polyvinyl alcohol, and 28 parts of water.

[0091] Everything else is exactly the same as in Example 3.

[0092] Comparative Example 4: This comparative example discloses an early-strength concrete material for the anchorage zone of expansion joints and its preparation method.

[0093] An early-strength concrete material for the anchorage zone of expansion joints comprises, by weight, 200 parts of cementitious masterbatch, 400 parts of coarse aggregate, 200 parts of fine aggregate, 20 parts of silica fume, 30 parts of mineral powder, and 5 parts of polycarboxylate superplasticizer; wherein the cementitious masterbatch comprises, by weight, 50 parts of tricalcium silicate, 120 parts of anhydrous calcium sulfoaluminate, 0.5 parts of polyvinyl alcohol, 1.5 parts of polypropylene fiber, and 28 parts of water.

[0094] Everything else is exactly the same as in Example 3.

[0095] The expansion joint anchorage zones prepared in Comparative Examples 1-4 were tested using early-strength concrete. The test results are shown in Table 4. Table 4: Indicator Name Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 1-day compressive strength (MPa) 5.8 7.0 6.7 6.5 3D compressive strength (MPa) 14.2 17.5 16.3 15.1 28-day compressive strength (MPa) 36.5 38.9 37.3 36.2 28-day flexural strength (MPa) 3.8 4.1 3.7 3.9 Slump of freshly mixed concrete (mm) 171 178 174 174 By comparing Comparative Example 1 and Example 3, it can be seen that Comparative Example 1 uses ordinary silicate cement as a cementitious material, and its hydration composition is complex, containing multiple mineral phases such as tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite. The hydration rate and product type of different components are significantly different, which can easily lead to internal temperature stress and microcracks. In contrast, Example 3 uses a cementitious masterbatch with tricalcium silicate and anhydrous calcium sulfoaluminate as the core, which has a single composition. During the hydration process, tricalcium silicate rapidly hydrates to generate CSH gel, which provides early strength, while anhydrous calcium sulfoaluminate hydrates simultaneously to generate ettringite to fill the pores. The synergistic effect of the two makes the hydration product structure dense and the interface bond strong, effectively avoiding the negative impact of the hydration of impurities. Therefore, the strength and toughness of Example 3 are better than those of Comparative Example 1.

[0096] By comparing Comparative Example 2 and Example 3, it can be seen that Comparative Example 2 lacks the polyvinyl alcohol component, and all performance test indicators are worse than those of Example 3. This reflects the key enhancing role of polyvinyl alcohol in the initial stage of hydration interface formation and bonding strength, as well as the dispersing effect of polyvinyl alcohol, which can reduce particle agglomeration and improve fluidity. However, Comparative Example 2 has slightly poorer fluidity due to the lack of this dispersing effect.

[0097] By comparing Comparative Example 3 with Example 3, it can be seen that Comparative Example 3, lacking the key polypropylene fiber component of Example 3, has significantly inferior performance indicators compared to Example 3. This is because the polypropylene fiber forms a three-dimensional network support structure inside the concrete. On the one hand, it can inhibit the initiation and expansion of microcracks in cement stone during hydration through the bridging effect, making stress transmission more uniform and thus improving compressive strength. On the other hand, the interfacial bonding between the fiber and the cement matrix can effectively prevent crack penetration, greatly improving the toughness and flexural strength of the material.

[0098] By comparing Comparative Example 4 with Example 3, it can be seen that Comparative Example 4 uses an excess of anhydrous calcium sulfoaluminate and an insufficient amount of tricalcium silicate. Although the short-term hydration rate may have a slight advantage due to the rapid formation of ettringite, the excess ettringite easily causes internal micro-stress and volume deformation. Moreover, the insufficient tricalcium silicate leads to a lack of CSH gel formation, making it difficult to form a continuous and stable structural support. The interfacial bonding and crack resistance are weak. Finally, the experimental data show that the later strength growth of Comparative Example 4 is slow, and the crack resistance and durability are significantly inferior to those of Example 3.

[0099] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A type of early-strength concrete material for the anchorage zone of expansion joints, characterized in that, The composition comprises, by weight, 200-250 parts of cementitious masterbatch, 400-450 parts of coarse aggregate, 200-250 parts of fine aggregate, 20-30 parts of silica fume, 30-60 parts of mineral powder, and 5-8 parts of polycarboxylate superplasticizer; wherein the composition of the cementitious masterbatch comprises, by weight, 110-130 parts of tricalcium silicate, 60-75 parts of anhydrous calcium sulfoaluminate, 0.5-1.0 parts of polyvinyl alcohol, 1.5-3.0 parts of polypropylene fiber, and 28-40 parts of water.

2. The early-strength concrete material for the anchorage zone of an expansion joint according to claim 1, characterized in that, The gel masterbatch further includes 0.4–1.2 parts of a silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite; wherein the mass ratio of silane coupling agent, tetrabutyl titanate, and polyethylene glycol is 0.4–0.6:1:2, and the molecular weight of the polyethylene glycol is 2000–4000; the preparation method of the silane-encapsulated tetrabutyl titanate-polyethylene glycol ternary composite is as follows: Preparation of silane-modified tetrabutyl titanate: Tetrabutyl titanate was mixed with γ-aminopropyltriethoxysilane and stirred at 60°C and 500-600 r / min for 2-3 hours to obtain surface-silanized tetrabutyl titanate. Synthesis of ternary composite: Polyethylene glycol was dissolved by heating in a water bath at 40-50°C. The tetrabutyl silanized titanate was mixed with anhydrous ethanol at a volume ratio of 1:1 and then added to the polyethylene glycol solution. The mixture was stirred at 400 r / min for 30-60 min. Aging treatment: After sealing, age at 20-25℃ for 3-5 hours, then cool naturally to room temperature to obtain the product.

3. The early-strength concrete material for the anchorage zone of an expansion joint according to claim 2, characterized in that, The polyethylene glycol is carboxyl-modified polyethylene glycol; the preparation method of the carboxyl-modified polyethylene glycol is as follows: polyethylene glycol and maleic anhydride are mixed at a mass ratio of 10:1, and benzoyl peroxide is added at a mass ratio of 0.5 wt% of the total mass of polyethylene glycol and maleic anhydride. The mixture is reacted at 120-130°C for 4-6 hours, cooled, washed three times with anhydrous ethanol, and dried under vacuum at 60°C to obtain the product.

4. A method for preparing early-strength concrete material for the anchorage zone of an expansion joint as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: Preparation of gel masterbatch: including the preparation steps of viscous mixed slurry and the shearing and sheeting steps; Preparation of viscous mixed slurry: Weigh tricalcium silicate, anhydrous calcium sulfoaluminate, polyvinyl alcohol, and polypropylene fiber according to the mass fractions, dry mix for 3-5 minutes, add water, wet mix for 5-8 minutes to form a viscous mixed slurry with a viscosity of 10000-15000 mPa·s. Shearing and sheet preparation: The viscous mixed slurry is sheared using a two-roll mill to obtain continuous sheets with a thickness of 2-5 mm; S2: Mixing and molding: First, weigh out the coarse aggregate, fine aggregate, silica fume, and mineral powder according to the mass fraction, and dry mix for 3-5 minutes to ensure that the inorganic aggregate and mineral admixture are mixed evenly; then add the product prepared from the cementitious masterbatch, dry mix for 2-3 minutes, add 5-8 parts of polycarboxylate superplasticizer, and dry mix to obtain concrete premix.

5. The method for preparing early-strength concrete material for the anchorage zone of expansion joints according to claim 4, characterized in that, In the shearing and sheeting step, biodegradable polylactic acid microspheres are added to the viscous mixed slurry, stirred evenly, and then sheared; the amount of polylactic acid microspheres added accounts for 0.7 to 1.0 wt% of the mass of the viscous mixed slurry.

6. The method for preparing early-strength concrete material for the anchorage zone of an expansion joint according to claim 4, characterized in that, The S1 step further includes a modification step, which is set after the shearing and sheeting step; the modification step is: immersing the sheet in an epoxy resin solution for 30-50 seconds, filtering and drying to form a uniform modified film on the sheet surface. The mass ratio of bisphenol A epoxy resin, diethylenetriamine, and anhydrous ethanol in the epoxy resin solution is 1:0.1-0.15:7-8.

7. The method for preparing early-strength concrete material for the anchorage zone of an expansion joint according to claim 6, characterized in that, The S1 step also includes a pre-impregnation step, which is set after the modification step; the pre-impregnation step is as follows: the epoxy resin modified gel masterbatch sheet is cut into square fragments, pre-impregnated in water at 30-40°C for 2-3 minutes, taken out and drained to obtain pre-impregnated sheet fragments; the amount of water used is 10-15 wt% of the sheet material weight.

8. The method for preparing early-strength concrete material for the anchorage zone of expansion joints according to claim 4, characterized in that, In step S2, steel fibers are added at a total mass of 0.2 to 0.3 wt% of the dry mix and the gelling masterbatch sheet.

9. A method for preparing early-strength concrete material for the anchorage zone of expansion joints according to any one of claims 4-8, characterized in that, In step S2, 0.1–0.2 wt% of silane coupling agent-modified calcium carbonate is added, comprising the total mass of the dry mix and the gelling masterbatch sheet, wherein the mass ratio of silane coupling agent to calcium carbonate is 1:100–200; the preparation method of the silane coupling agent-modified calcium carbonate is as follows: Stir calcium carbonate at 60–80°C and 800–1000 r / min for 10–15 min; spray γ-aminopropyltriethoxysilane evenly and continue stirring for 30–40 min; lower the temperature to 40–50°C and stir for 20–30 min; cool to room temperature and pass through a 200-mesh sieve to remove agglomerated particles to obtain the final product.

10. A method of using an early-strength concrete material for the anchorage zone of an expansion joint as described in any one of claims 1-3, or an early-strength concrete material for the anchorage zone of an expansion joint prepared by the preparation method described in any one of claims 4-9, characterized in that... The premixed concrete prepared in step S2 is mixed with 80-100 parts water on site according to the mass of the premixed concrete, stirred evenly, and then cured.