Anti-freezing concrete prefabricated component and preparation method thereof

Abstract

The invention relates to the technical field of building materials, and particularly discloses an anti-freezing concrete prefabricated part and a preparation method thereof, the anti-freezing concrete prefabricated part comprises the following raw materials by weight: 300-360 parts of cement, 40-60 parts of fly ash, 90-110 parts of mineral powder, 642-662 parts of natural sand, 1000-1100 parts of gravel, 7-9 parts of an additive, 150-170 parts of water, 0.5-1.5 parts of polypropylene glycol fiber, and 3-8 parts of phase change self-repairing microcapsules. The prepared anti-freezing concrete prefabricated part has the advantage of being good in anti-freezing performance.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a precast frost-resistant concrete component and its preparation method. Background Technology

[0002] In the field of construction engineering, concrete, as an important building material, plays a crucial role in the safety and durability of building structures. With the continuous development of the construction industry, the performance requirements for concrete are becoming increasingly stringent. In some cold regions, concrete structures face the severe challenge of freeze-thaw damage, which not only affects the appearance of buildings but also reduces their load-bearing capacity and service life. Therefore, developing concrete materials with good freeze-thaw resistance has become an important research direction in the field of building materials. The emergence of freeze-thaw resistant precast concrete components provides a new approach to solving the problem of freeze-thaw damage in concrete structures in cold regions, and is of great significance for improving the quality and durability of construction projects.

[0003] In traditional concrete preparation, various techniques are typically employed to improve concrete performance. For ordinary concrete, cement, sand, gravel, and water are generally used as basic raw materials, with a well-designed mix proportion to meet specific strength requirements. To improve workability, admixtures such as water-reducing agents and air-entraining agents are often added. To address frost resistance, a common practice is to incorporate mineral admixtures, such as fly ash and mineral powder, to improve the internal structure, density, and impermeability of the concrete. Additionally, adjusting aggregate gradation and selecting suitable natural sand and crushed stone optimizes the pore structure and enhances frost resistance. However, these methods are often used individually or in simple combinations, lacking a comprehensive consideration of multiple factors.

[0004] Existing technologies for preparing precast concrete components with freeze-thaw resistance have significant shortcomings. Traditional concrete preparation methods are insufficient to meet the requirements for freeze-thaw resistance in cold environments. Ordinary raw material mix proportions and single technical means cannot effectively address the internal damage that occurs in concrete during freeze-thaw cycles. For example, simply adding mineral admixtures or adjusting aggregate gradation cannot fundamentally improve the freeze-thaw resistance of concrete. After multiple freeze-thaw cycles, internal cracks and spalling easily occur in the concrete, leading to a decrease in its strength and durability. Therefore, a new technical solution is needed to improve the freeze-thaw resistance of precast concrete components. Summary of the Invention

[0005] To improve the frost resistance of precast concrete components, this application provides a frost-resistant precast concrete component and its preparation method.

[0006] In a first aspect, this application provides a precast frost-resistant concrete component, which adopts the following technical solution: A precast frost-resistant concrete component comprises the following raw materials in parts by weight: 300-360 parts cement, 40-60 parts fly ash, 90-110 parts mineral powder, 642-662 parts natural sand, 1000-1100 parts crushed stone, 7-9 parts admixture, 150-170 parts water, 0.5-1.5 parts polyacrylamide fiber, and 3-8 parts phase change self-healing microcapsules.

[0007] By adopting the above technical solutions, cement, fly ash, and mineral powder form a cementitious system. Cement hydration provides basic strength, while the secondary hydration reaction of fly ash and mineral powder further fills pores, optimizes the structure, and improves density and durability. Natural sand and crushed stone form a reasonable gradation skeleton, enhancing the load-bearing capacity of the components. Appropriate admixtures adjust the workability of concrete, ensuring smooth construction. Polyacrylamide fibers form a randomized support system inside the concrete, effectively constraining the propagation of microcracks, absorbing some of the internal stress caused by frost heave or shrinkage, and reducing the probability of crack generation and propagation. The phase change material in the phase change self-healing microcapsules can undergo phase change when the temperature changes, absorbing or releasing heat, regulating the internal temperature of the concrete, reducing cracking caused by temperature stress, thereby improving the frost resistance and durability of precast concrete components.

[0008] Optionally, the phase change self-healing microcapsules include 60-80 parts of hemihydrate gypsum powder, 20-40 parts of organosilicon prepolymer, 25-35 parts of stearic acid, 0.05-0.15 parts of platinum catalyst, 0.25-0.4 parts of nano-silica, and 0.02-0.05 parts of diethyl maleate.

[0009] By adopting the above technical solution, stearic acid, as a phase change material, can undergo solid-liquid or liquid-solid phase change when the temperature changes, absorbing or releasing a large amount of heat, effectively regulating the internal temperature of concrete, reducing stress caused by temperature fluctuations, and lowering the risk of cracking. When cracks appear in the concrete, the microcapsules rupture, and the hemihydrate gypsum powder rapidly hydrates to form gypsum, quickly filling the crack space and playing a preliminary sealing role. The organosilicon prepolymer undergoes a cross-linking and curing reaction under the catalysis of a platinum catalyst, forming an elastoplastic network with good flexibility and adhesion, compensating for the brittleness of gypsum and blocking secondary water intrusion, and can further tightly fill the cracks and firmly bond with the surrounding concrete. With its high specific surface area and activity, nano-silica can not only fill micro-cracks, but also produce physicochemical interactions with gypsum and cured organosilicon, enhancing the density and strength of the crack repair site. The multi-component synergy achieves efficient self-repair, significantly improving the freeze-thaw resistance and durability of the concrete structure.

[0010] Optionally, the preparation of the phase change self-healing microcapsules includes the following steps: (1) Mix hemihydrate gypsum powder, organosilicon prepolymer, diethyl maleate and platinum catalyst and granulate to form wet particles with a particle size of 50-80 μm. (2) Stearic acid is heated to complete liquefaction and then mixed with nano-silica. Its viscosity is controlled to be 200-300 mPa·s. After atomization, it is evenly sprayed onto the surface of wet particles. Particles with a particle size between 100-150 μm are collected to obtain phase change self-healing microcapsules.

[0011] By adopting the above technical solution, in step (1), hemihydrate gypsum powder, organosilicon prepolymer and platinum catalyst are stirred, mixed and granulated. Hemihydrate gypsum powder serves as the base material for subsequent hydration repair. Organosilicon prepolymer has curing repair capability under the potential catalytic action of platinum catalyst. The two combine to form a wet particle core with repair potential. Diethyl maleate can inhibit the activity of platinum catalyst. After the microcapsules rupture and water invades, hydrolysis occurs, which increases the activity of platinum catalyst and promotes the reaction and curing of organosilicon prepolymer. In step (2), stearic acid is heated and liquefied, mixed with nano-silica and the viscosity is controlled. Then it is atomized and sprayed on the surface of wet particles. Stearic acid, as a phase change material, can adjust temperature stress. Nano-silica can enhance repair strength and density. Atomized spraying makes the two uniformly wrap the wet particles to form a core-shell structure. When cracks appear in concrete, the microcapsules rupture, hemihydrate gypsum powder hydrates, and organosilicon prepolymer is cured under the action of platinum catalyst. Stearic acid and nano-silica work together to achieve efficient self-repair, significantly improving the freeze-thaw resistance and durability of concrete.

[0012] Optionally, the organosilicon prepolymer is a vinyl-terminated polydimethylsiloxane.

[0013] By adopting the above technical solution, a dual breakthrough of low-temperature rapid curing and elastoplastic synergistic repair has been achieved. The vinyl end groups form π-allyl complexes with the platinum catalyst, significantly reducing the activation energy of the hydrosilylation reaction, enabling the material to cure rapidly at low temperatures without the formation of byproducts, ensuring repair efficiency and material purity. The ultra-flexible nature of the polydimethylsiloxane backbone endows the cured product with high elongation at break and low surface energy, effectively absorbing concrete frost heave deformation and preventing secondary cracking, while also blocking moisture penetration through the arrangement of hydrophobic methyl groups. During the repair process, the vinyl-terminated polydimethylsiloxane forms a rigid-flexible interpenetrating network with the gypsum expander. The gypsum fills the main crack, while the vinyl-terminated polydimethylsiloxane elastically and plastically coats the repair area, resisting frost heave stress and enhancing interfacial adhesion. Simultaneously, the low-temperature rapid curing characteristic ensures crack compactness, and the zero-shrinkage characteristic prevents interfacial debonding, thereby comprehensively improving the frost resistance and durability of concrete.

[0014] Optionally, the admixtures include 80-85 wt% polycarboxylate superplasticizer, 10-12 wt% air-entraining agent, and 5-8 wt% retarder.

[0015] By adopting the above technical solution, the workability and durability of concrete are significantly improved through the synergistic effect of polycarboxylate superplasticizer, air-entraining agent, and retarder. The polycarboxylate superplasticizer, with its comb-like molecular structure, efficiently disperses cement particles through electrostatic repulsion and steric hindrance, significantly reducing water consumption and improving slurry fluidity. The air-entraining agent introduces micron-sized closed air bubbles during mixing, forming an elastic buffer layer to absorb frost heave stress and improve the concrete's resistance to segregation. The retarder, by adsorbing onto the surface of cement minerals, slows down the hydration process, avoiding internal defects caused by rapid setting and extending the construction window. The combined effect of the superplasticizer and air-entraining agent optimizes the bubble size distribution, while the retarder's regulation of the hydration rhythm ensures bubble stability, ultimately endowing the concrete with high fluidity, excellent freeze-thaw resistance, and good construction adaptability.

[0016] Secondly, this application provides a method for preparing frost-resistant precast concrete components, employing the following technical solution: A method for preparing frost-resistant precast concrete components includes the following steps: After mixing cement, fly ash, mineral powder, natural sand and crushed stone, dry mix for 40-60 seconds; add water, admixtures and polyacryl alcohol fiber and stir evenly, then add phase change self-healing microcapsules, reduce the speed and stir, and then put it into a mold for preliminary shaping. The pre-formed concrete is steam-cured under the following conditions: temperature controlled at 40-50℃, humidity ≥95%, and curing time of 6-8 hours to obtain frost-resistant precast concrete components.

[0017] By adopting the above technical solutions, the dry mixing stage ensures that the cementitious materials and aggregates are fully mixed to form a uniform skeleton. After the subsequent addition of water, admixtures, and polyacrylamide fibers, the fibers disperse in the slurry to form a three-dimensional support network, effectively inhibiting the propagation of microcracks. The phase change self-healing microcapsules are uniformly embedded in the matrix under low-speed stirring. Their shells can protect the core repair agent from early hydration and prevent fiber agglomeration. Steam curing accelerates the cement hydration reaction to generate a dense ettringite structure by precisely controlling temperature and humidity conditions, promoting the secondary hydration of fly ash and mineral powder, and improving the strength of the interface transition zone. Moderate heating can prevent the microcapsule shells from softening and leaking prematurely, ensuring that the repair agent can play a self-healing role during the service stage of the component, ultimately obtaining precast components with high frost resistance, low permeability, and excellent durability.

[0018] Optionally, the steam-cured concrete surface is sprayed with a superhydrophobic layer, which is composed of a silane coupling agent and a fluorinated polysiloxane, wherein the weight ratio of the silane coupling agent to the fluorinated polysiloxane is 1:0.8-1.2.

[0019] Optionally, the superhydrophobic layer is formed by uniformly spraying the mixed raw materials onto the surface of the precast concrete component, with a spray thickness of 700-900 μm.

[0020] By employing the above-mentioned technical solution, a superhydrophobic layer composed of silane coupling agent and fluorinated polysiloxane in a specific ratio is sprayed onto the surface of steam-cured concrete. The core mechanism lies in the synergistic construction of a micro-nano rough structure and a low surface energy coating: the silanol groups (-Si-OH) generated by the hydrolysis of the silane coupling agent undergo a condensation reaction with the hydroxyl groups (-OH) on the concrete surface, forming a chemically bonded anchoring layer. Simultaneously, its alkyl chains extend outwards, providing initial roughness. The fluorocarbon groups (such as -CF3) in the fluorinated polysiloxane have extremely low surface energy, covering the anchoring layer surface through a dual action of physical adsorption and chemical bonding, further amplifying the roughness to the micro-nano scale, forming a two-tiered structure similar to the "lotus effect." This composite coating increases the contact angle of the concrete surface, significantly reduces water penetration, and inhibits the intrusion of corrosive media such as chloride ions and sulfates. Together with the dense matrix formed by steam curing, it constitutes a "barrier-self-healing" dual protection system, greatly improving the durability of precast components under harsh environments such as freeze-thaw cycles and salt corrosion.

[0021] In summary, this application has the following beneficial effects: 1. This application achieves dual protection—from microcrack suppression to macrostructural repair—through a composite design of phase change self-healing microcapsules and polyacrylamide fibers. When the microcapsules rupture, the released gypsum forms a rigid-flexible interpenetrating network with the organosilicon prepolymer, rapidly filling cracks and blocking moisture intrusion; the fibers, through their three-dimensional random distribution, constrain the propagation of microcracks and absorb frost heave stress. Together, they construct a dynamically responsive repair mechanism, significantly improving the crack resistance and durability of concrete under freeze-thaw cycles.

[0022] 2. The method of this application constructs a superhydrophobic layer with a micro-nano rough structure on the concrete surface through the synergistic effect of chemical bonding and physical adsorption between silane coupling agents and fluorinated polysiloxanes. This coating complements the low-porosity matrix formed by steam curing, significantly reducing water penetration through the "lotus leaf effect" and inhibiting the intrusion of corrosive media by utilizing the chemical inertness of fluorocarbon groups. This constructs a dual protection system of "barrier-self-healing" from the outside in, significantly improving the service life of components under combined harsh environments such as salt corrosion and freeze-thaw cycles. Detailed Implementation

[0023] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0024] Vinyl-terminated polydimethylsiloxane was purchased from Hubei Xinjiecheng Chemical Technology Co., Ltd., CAS No. 68083-19-2; Preparation Example

[0025] Preparation Example 1 A self-healing phase change microcapsule includes the following preparation steps: (1) Weigh 70kg hemihydrate gypsum powder, 30kg vinyl-terminated polydimethylsiloxane (organosilicon prepolymer), 0.035kg diethyl maleate and 0.1kg platinum catalyst. Stir at 200rpm for 15min until evenly mixed and then pass into a centrifugal granulator to form wet particles with a particle size of 50-80μm. (2) After heating 30 kg of stearic acid to 70 °C and completely liquefying it, add 0.35 kg of nano silica and stir at 500 rpm for 5 min to mix evenly. Control its viscosity to 250 mPa·s, atomize it and spray it evenly on the surface of wet particles, collect particles with a particle size between 100-150 μm, and obtain phase change self-healing microcapsules.

[0026] Preparation Example 2 A self-healing phase change microcapsule includes the following preparation steps: (1) Weigh 70kg hemihydrate gypsum powder, 30kg vinyl-terminated polydimethylsiloxane (organosilicon prepolymer), 0.02kg diethyl maleate and 0.1kg platinum catalyst. Stir at 200rpm for 15min until evenly mixed and then pass into a centrifugal granulator to form wet particles with a particle size of 50-80μm. (2) After heating 30 kg of stearic acid to 70 °C and completely liquefying it, add 0.35 kg of nano silica and stir at 500 rpm for 5 min to mix evenly. Control its viscosity to 200 mPa·s, atomize it and spray it evenly on the surface of wet particles, collect particles with a particle size between 100-150 μm, and obtain phase change self-healing microcapsules.

[0027] Preparation Example 3 A self-healing phase change microcapsule includes the following preparation steps: (1) Weigh 70kg hemihydrate gypsum powder, 30kg vinyl-terminated polydimethylsiloxane (organosilicon prepolymer), 0.05kg diethyl maleate and 0.1kg platinum catalyst. Stir at 200rpm for 15min until evenly mixed and then pass into a centrifugal granulator to form wet particles with a particle size of 50-80μm. (2) After heating 30 kg of stearic acid to 70 °C and completely liquefying it, add 0.35 kg of nano silica and stir at 500 rpm for 5 min to mix evenly. Control its viscosity to 300 mPa·s, atomize it and spray it evenly on the surface of wet particles, collect particles with a particle size between 100-150 μm, and obtain phase change self-healing microcapsules.

[0028] Example Example 1 A precast frost-resistant concrete component includes the following preparation method: Mix 330kg cement, 50kg fly ash, 100kg mineral powder, 652kg natural sand and 1000kg crushed stone and dry mix for 50s; add 160kg water, 8kg admixture and 1kg polyacrylamide fiber and stir evenly; add 5kg of the phase change self-healing microcapsules prepared in Example 1, reduce the speed and stir, and put them into a mold for preliminary molding. The pre-formed concrete was steam-cured under the following conditions: temperature controlled at 45℃, humidity ≥95%, and curing for 7 hours to obtain frost-resistant precast concrete components. The admixtures include 6.6 kg of polycarboxylate superplasticizer, 0.88 kg of sodium dodecyl sulfate (air-entraining agent), and 0.52 kg of sodium gluconate (retarder).

[0029] Example 2 A precast frost-resistant concrete component includes the following preparation method: Mix 300kg cement, 60kg fly ash, 110kg mineral powder, 662kg natural sand and 1100kg crushed stone and dry mix for 40s; add 150kg water, 7kg admixture and 1.5kg polyacryl alcohol fiber and stir evenly; add 3kg of the phase change self-healing microcapsules prepared in Example 1, reduce the speed and stir, and put them into a mold for preliminary molding. The pre-formed concrete was steam-cured under the following conditions: temperature controlled at 40℃, humidity ≥95%, and curing for 8 hours to obtain frost-resistant precast concrete components. The admixtures include 5.95 kg of polycarboxylate superplasticizer, 0.7 kg of sodium dodecyl sulfate (air-entraining agent), and 0.35 kg of sodium gluconate (retarder).

[0030] Example 3 A precast frost-resistant concrete component includes the following preparation method: Mix 360kg cement, 40kg fly ash, 90kg mineral powder, 642kg natural sand and 1050kg crushed stone and dry mix for 40-60s; add 170kg water, 9kg admixture and 0.5kg polyacryl alcohol fiber and stir evenly; add 8kg of the phase change self-healing microcapsules prepared in Example 1, reduce the speed and stir, and put them into a mold for preliminary molding. The pre-formed concrete was steam-cured under the following conditions: temperature controlled at 50℃, humidity ≥95%, and curing for 6 hours to obtain frost-resistant precast concrete components. The admixtures include 7.2 kg of polycarboxylate superplasticizer, 1.08 kg of sodium dodecyl sulfate (air-entraining agent), and 0.72 kg of sodium gluconate (retarder).

[0031] Example 4 A precast concrete component resistant to freezing, which differs from Example 1 in that the phase change self-healing microcapsules used in this example were prepared in Example 2.

[0032] Example 5 A precast frost-resistant concrete component differs from Example 1 in that the phase change self-healing microcapsules used in this example were prepared in Example 3.

[0033] Example 6 A precast frost-resistant concrete component differs from Example 1 in that a superhydrophobic layer is coated on the surface of the precast concrete component in this example, as detailed below: γ-aminopropyltriethoxysilane (silane coupling agent) and perfluoropolyether polyfluorosiloxane (fluorinated polysiloxane) were added to butyl acetate in a weight ratio of 1:1 to form an 80 wt% superhydrophobic coating solution for later use. The prepared superhydrophobic coating solution was uniformly sprayed onto the surface of precast concrete components with a coating thickness of 800 μm. The remaining steps were the same as in Example 1.

[0034] Example 7 A precast frost-resistant concrete component differs from Example 1 in that a superhydrophobic layer is coated on the surface of the precast concrete component in this example, as detailed below: γ-aminopropyltriethoxysilane (silane coupling agent) and perfluoropolyether polyfluorosiloxane (fluorinated polysiloxane) were added to butyl acetate at a weight ratio of 1:0.8 to form an 80wt% superhydrophobic coating solution for later use. The prepared superhydrophobic coating solution was uniformly sprayed onto the surface of precast concrete components to a thickness of 700μm. The remaining steps were the same as in Example 1.

[0035] Example 8 A precast frost-resistant concrete component differs from Example 1 in that a superhydrophobic layer is coated on the surface of the precast concrete component in this example, as detailed below: γ-aminopropyltriethoxysilane (silane coupling agent) and perfluoropolyether polyfluorosiloxane (fluorinated polysiloxane) were added to butyl acetate in a weight ratio of 1:1.2 to form an 80 wt% superhydrophobic coating solution for later use. The prepared superhydrophobic coating solution was uniformly sprayed onto the surface of precast concrete components to a thickness of 900 μm. The remaining steps were the same as in Example 1.

[0036] Comparative Example Comparative Example 1 A precast concrete component resistant to freezing, which differs from Example 1 in that phase change self-healing microcapsules were not added in this comparative example.

[0037] Comparative Example 2 A precast concrete component resistant to freezing, which differs from Example 1 in that polyacrylamide fiber was not added in this comparative example.

[0038] Performance testing Detection methods / test methods

[0039] Compressive strength: The mechanical properties of the antifreeze concrete precast components prepared in the examples and comparative examples were tested in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The specific results are shown in Table 1. Freeze-thaw resistance: The slow freezing method test was carried out in accordance with the "Test Method for Freeze-Thaw Resistance of Concrete" (GB / T50082-2024). The test was conducted by cyclic freezing and thawing between -20℃ and 20℃. The mass loss and compressive strength loss were measured every 25 cycles and recorded in Table 1.

[0040] Table 1 Test Data

[0041] Combining Examples 1-3 and Comparative Example 1 with Table 1, it can be seen that the experimental data of Examples 1-3 are all superior to those of Comparative Example 1, indicating that the addition of phase change self-healing microcapsules can significantly improve the freeze-thaw resistance and durability of precast concrete components. The phase change material in the phase change self-healing microcapsules undergoes a phase change when the temperature changes, absorbing or releasing heat, regulating the internal temperature of the concrete, and reducing cracking caused by temperature stress. Simultaneously, when cracks appear in the concrete, the microcapsules rupture to release the repair material, quickly filling the cracks and preventing moisture intrusion, further enhancing the freeze-thaw resistance and durability of the concrete.

[0042] Combining Examples 1-3 and Comparative Example 2 with Table 1, it can be seen that the experimental data of Examples 1-3 are all superior to those of Comparative Example 2. This indicates that polyacrylamide fibers form a randomized support system inside the concrete, effectively constraining the propagation of microcracks, absorbing some of the internal stress caused by frost heave or drying shrinkage, and reducing the probability of crack initiation and propagation, thereby improving the frost resistance and durability of precast concrete components. The addition of polyacrylamide fibers enhances the toughness of concrete, enabling it to better resist damage caused by freeze-thaw cycles.

[0043] As can be seen from Examples 1-5 and Table 1, the phase change self-healing microcapsules prepared by the method of this application can improve the freeze-thaw resistance of precast concrete components to a certain extent.

[0044] Combining Examples 1 and 6-8 with Table 1, it can be seen that the experimental data of Examples 6-8 are all better than those of Example 1. This indicates that the further coating of the superhydrophobic coating can significantly reduce water penetration and inhibit the intrusion of corrosive media. Together with the dense substrate formed by steam curing, it constitutes a "barrier-self-healing" dual protection system, which greatly improves the durability of precast components in environments such as freeze-thaw cycles.

[0045] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A precast frost-resistant concrete component, characterized in that, Including the following parts by weight of raw materials: 300-360 parts cement, 40-60 parts fly ash, 90-110 parts mineral powder, 642-662 parts natural sand, 1000-1100 parts crushed stone, 7-9 parts admixture, 150-170 parts water, 0.5-1.5 parts polyacrylamide fiber, and 3-8 parts phase change self-healing microcapsules.

2. The precast frost-resistant concrete component according to claim 1, characterized in that: The phase change self-healing microcapsules comprise 60-80 parts of hemihydrate gypsum powder, 20-40 parts of organosilicon prepolymer, 25-35 parts of stearic acid, 0.05-0.15 parts of platinum catalyst, 0.25-0.4 parts of nano-silica, and 0.02-0.05 parts of diethyl maleate.

3. The precast frost-resistant concrete component according to claim 1, characterized in that, The preparation of the phase change self-healing microcapsules includes the following steps: (1) Mix hemihydrate gypsum powder, organosilicon prepolymer, diethyl maleate and platinum catalyst and granulate to form wet particles with a particle size of 50-80 μm. (2) Stearic acid is heated to complete liquefaction and then mixed with nano-silica. Its viscosity is controlled to be 200-300 mPa·s. After atomization, it is evenly sprayed onto the surface of wet particles. Particles with a particle size between 100-150 μm are collected to obtain phase change self-healing microcapsules.

4. A precast frost-resistant concrete component according to claim 1, characterized in that: The organosilicon prepolymer is a vinyl-terminated polydimethylsiloxane.

5. A precast frost-resistant concrete component according to claim 1, characterized in that: The admixtures include polycarboxylate superplasticizer accounting for 80-85 wt% of the total admixtures, air-entraining agent accounting for 10-12 wt% of the total admixtures, and retarder accounting for 5-8 wt% of the total admixtures.

6. The method for preparing frost-resistant precast concrete components according to any one of claims 1-5, characterized in that, Includes the following steps: After mixing cement, fly ash, mineral powder, natural sand and crushed stone, dry mix for 40-60 seconds; add water, admixtures and polyacryl alcohol fiber and stir evenly, then add phase change self-healing microcapsules, reduce the speed and stir, and then put it into a mold for preliminary shaping. The pre-formed concrete is steam-cured under the following conditions: temperature controlled at 40-50℃, humidity ≥95%, and curing time of 6-8 hours to obtain frost-resistant precast concrete components.

7. The method for preparing a precast frost-resistant concrete component according to claim 1, characterized in that: The concrete surface after steam curing is sprayed with a superhydrophobic layer, which includes a silane coupling agent and a fluorinated polysiloxane, with a weight ratio of silane coupling agent to fluorinated polysiloxane of 1:0.8-1.

2.

8. A precast frost-resistant concrete component according to claim 1, characterized in that: The superhydrophobic layer is formed by uniformly mixing all raw materials and then spraying them evenly onto the surface of precast concrete components, with a spray thickness of 700-900μm.

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