Low temperature resistant crack resistant concrete and preparation method thereof

Abstract

The present application relates to the field of concrete, specifically disclosing a low-temperature-resistant and crack-resistant concrete and its preparation method. The low-temperature-resistant and crack-resistant concrete comprises the following raw materials by weight: 95-105 parts of mineral material and 3-9 parts of modified polyurethane; the modified polyurethane comprises the following raw materials by weight: 4-8 parts of polyurethane and 1.3-1.7 parts of modified hydrotalcite; the modified hydrotalcite comprises the following raw materials by weight: 2.1-2.9 parts of hydrotalcite and 0.4-0.8 parts of vinyl prepolymer; and the preparation method comprises: weighing 95-105 parts of mineral material, placing it at 20°C to 30°C, and mixing it with 3-9 parts of modified polyurethane and stirring it evenly. The low-temperature-resistant and crack-resistant concrete of the present application has the advantage of improving the durability of low-temperature-resistant and crack-resistant concrete, which still has some shortcomings.

Description

Technical Field

[0001] The present application relates to the field of concrete technology, and more specifically, to a low-temperature resistant and crack-resistant concrete and a preparation method thereof. Background Art

[0002] Concrete, a rigid building material, is made by mixing a binder (usually Portland cement, also known as ordinary cement or Portland cement) with mineral aggregates (such as clean sand and gravel or crushed stone) and sufficient water to solidify and bind the cement. With the rapid urbanization and increasing demands for building functionality, shortcomings in the performance and applicability of existing concrete materials have become apparent. Western China's high-altitude regions, characterized by large diurnal temperature swings, severe cold and dry conditions, strong solar radiation, and deep permafrost, experience severe freeze-thaw damage to concrete, significantly reducing its durability. After 5 to 10 years of use, concrete building materials on the Qinghai-Tibet Plateau can develop surface pulverization, exposed aggregates, and crumble with light tapping. This significantly shortens the service life of concrete structures and poses safety risks. Therefore, improving the low-temperature crack resistance and performance of concrete in these high-altitude regions is crucial for extending its service life.

[0003] Polyurethane concrete is widely used in building materials because of its excellent low-temperature resistance, good flexibility at low temperatures, and resistance to cracking after repeated freezing and thawing. However, since polyurethane itself is not resistant to ultraviolet rays, long-term exposure to ultraviolet rays will cause polyurethane aging, thereby affecting the durability of concrete. Summary of the Invention

[0004] In order to improve the defect that the durability of low-temperature resistant and crack-resistant concrete is still insufficient, the present application provides a low-temperature resistant and crack-resistant concrete and a preparation method thereof.

[0005] In the first aspect, the present application provides a low-temperature resistant and crack-resistant concrete, which adopts the following technical solutions:

[0006] A low-temperature resistant and crack-resistant concrete comprising the following raw materials in parts by weight: 95-105 parts of mineral material and 3-9 parts of modified polyurethane;

[0007] The modified polyurethane comprises the following raw materials in parts by mass: 4-8 parts of polyurethane and 1.3-1.7 parts of modified hydrotalcite;

[0008] The modified hydrotalcite comprises the following raw materials in parts by mass: 2.1-2.9 parts of hydrotalcite and 0.4-0.8 parts of vinyl prepolymer.

[0009] Because polyurethane contains urethane bonds and ether bonds, these bonds are easily broken under ultraviolet light, causing material degradation. Ultraviolet rays can excite oxygen atoms in polyurethane to produce free radicals, thereby triggering a chain oxidation reaction. This photooxidation will destroy the long-chain molecular structure of polyurethane and reduce its physical properties. Hydrotalcite has a layered structure, consisting of two layers of positively charged metal hydroxide layers and a layer of negatively charged interlayer anions. Its interlayer anions can absorb ultraviolet rays, thereby reducing the damage of ultraviolet rays to polyurethane. The anti-aging properties of polyurethane are also improved, thereby improving the durability of concrete.

[0010] Since hydrotalcite, as an inorganic substance, has strong hydrophilicity, it has poor dispersion when mixed with polyurethane. Vinyl prepolymer has unique hydrophilicity. This hydrophilic property enables the vinyl prepolymer to be adsorbed on the surface of hydrotalcite particles, forming a coating layer, which reduces direct contact between hydrotalcite particles and thus reduces the possibility of hydrotalcite agglomeration.

[0011] Preferably, the vinyl prepolymer comprises the following raw materials in parts by mass: 1.5-3.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1-1.6 parts of acrylic acid, 0.5-0.9 parts of sodium p-styrenesulfonate, 0.5-1.5 parts of dimethyldiallylammonium chloride, 3-3.8 parts of acrylamide, 0.02-0.08 parts of initiator and 0.15-0.21 parts of modified phosphide.

[0012] Since 2-acrylamido-2-methylpropanesulfonic acid contains sulfonic acid groups, the sulfonic acid groups can interact with the metal ions of hydrotalcite. Acrylic acid contains carboxyl groups and can also interact with the surface of hydrotalcite. Sodium p-styrenesulfonate contains benzene rings and sulfonic acid groups. The benzene rings provide hydrophobic effects, and the sulfonic acid groups provide hydrophilic effects, which help to regulate the interfacial interaction between the prepolymer and hydrotalcite. Dimethyldiallylammonium chloride is a cationic monomer that can neutralize the negative charges on the surface of hydrotalcite, reduce the electrostatic attraction between particles, and thus improve dispersibility. The macromolecular chains formed by polymerization of acrylamide can provide steric hindrance, thereby reducing the agglomeration between hydrotalcite particles.

[0013] Preferably, the preparation method of the vinyl prepolymer is as follows: 1.5-3.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1-1.6 parts of acrylic acid, 0.5-0.9 parts of sodium p-styrenesulfonate and 0.15-0.21 parts of modified phosphide are weighed and added to a beaker, 15-25 ml of deionized water is added for dissolution, the pH value is adjusted, and then 0.5-1.5 parts of dimethyldiallylammonium chloride, 3-3.8 parts of acrylamide and 0.02-0.08 parts of initiator are added, and the mixture is stirred evenly to completely dissolve all monomers. After nitrogen is passed through for 5-15 minutes, the mixture is placed in a constant temperature water bath at 45-55° C. and reacted for 4-8 hours. The mixture is washed with anhydrous ethanol and then sheared and granulated.

[0014] Preferably, the modified phosphide comprises the following raw materials: 1-3 g of triaminomethylphosphine oxide, 1-2 g of hexachlorocyclotriphosphazene, 0.5-1.5 g of melamine, 35-65 ml of N,N-dimethylformamide, and 2-8 ml of triethylamine.

[0015] Since concrete is mainly composed of inorganic materials such as cement, sand, gravel and water, these materials do not contain organic combustible substances under normal conditions, so they are not easy to burn and have good flame retardant properties. Polyurethane contains a large amount of carbon and hydrogen atoms. During the combustion process, these carbon and hydrogen atoms easily react chemically with oxygen, thereby releasing heat and combustible gases, accelerating the combustion process, and thus causing the overall flame retardant properties of concrete to decline.

[0016] Triaminomethylphosphine oxide contains phosphorus, which can form phosphoric acid or its derivatives during combustion. These substances can act as an acid source to promote carbonization, forming a carbon layer to isolate oxygen and heat, thereby preventing further combustion. Since hexachlorocyclotriphosphazene and melamine can form a polyphosphazene structure, the polyphosphazene structure formed by hexachlorocyclotriphosphazene and melamine is rich in P and N elements, which can also improve the flame retardant properties of triaminomethylphosphine oxide. Hexachlorocyclotriphosphazene contains multiple chlorine atoms and phosphorus atoms, which can absorb ultraviolet energy. Melamine itself has a certain ultraviolet light stabilization effect. Therefore, the addition of modified phosphide can not only improve the ultraviolet resistance of the modified polyurethane, but also improve the flame retardant properties of the polyurethane.

[0017] Preferably, the preparation method of the modified phosphide is as follows: 1-3 g of triamine methylphosphine oxide is weighed and dispersed in 15-25 ml of N, N-dimethylformamide, and placed in an ice bath for stirring; 1-2 g of hexachlorocyclotriphosphazene is weighed and added to a beaker, and ultrasonically dispersed with 5-15 ml of N, N-dimethylformamide, and then added dropwise to the triamine methylphosphine oxide dispersion; after the addition is complete, the reaction is continued for 25-35 minutes to obtain a dispersion liquid 1; 0.5-1.5 g of melamine is weighed and added to a beaker, and 15-25 ml of After ultrasonic dispersion, N,N-dimethylformamide is added dropwise to the above dispersion liquid 1 to obtain dispersion liquid 2. 2-8 ml of triethylamine is continued to be added dropwise to the above dispersion liquid 2. After the addition is completed, the reaction is continued for 25-35 minutes to obtain dispersion liquid 3. The evenly stirred dispersion liquid 3 is poured into a high-pressure reactor and reacted at 100-140°C for 24-28 hours. The mixture is then centrifuged at a high speed. The product is then dried at 75-85°C for 2-8 hours and ground into powder.

[0018] Preferably, the modified hydrotalcite is prepared by weighing 2.1-2.9 parts of hydrotalcite and 0.4-0.8 parts of vinyl prepolymer, mixing them evenly, drying them in an oven at 75-85°C for 6-10 hours, extruding them into granules at 210-250°C on an extruder, and injection molding them.

[0019] Preferably, the preparation method of the modified polyurethane is as follows: 1.3-1.7 parts of modified hydrotalcite are added to 4-8 parts of polyurethane and stirred evenly, and then placed in a high-speed shearing machine for shearing treatment.

[0020] In a second aspect, the present application provides a method for preparing low-temperature resistant and crack-resistant concrete, which adopts the following technical solution:

[0021] A preparation method of low-temperature resistant and crack-resistant concrete comprises the following steps: weighing 95-105 parts of mineral materials, placing them at 20-30 DEG C, and mixing them with 3-9 parts of modified polyurethane and stirring them evenly.

[0022] In summary, this application has the following beneficial effects:

[0023] 1. Since polyurethane contains urethane bonds and ether bonds, these bonds are easily broken under ultraviolet radiation, leading to material degradation. Ultraviolet rays can excite oxygen atoms in polyurethane to produce free radicals, thereby triggering a chain oxidation reaction. This photooxidation will destroy the long-chain molecular structure of polyurethane and reduce its physical properties. Hydrotalcite has a layered structure, consisting of two layers of positively charged metal hydroxide layers and a layer of negatively charged interlayer anions. Its interlayer anions can absorb ultraviolet rays, thereby reducing the damage of ultraviolet rays to polyurethane. The anti-aging properties of polyurethane are also improved, thereby improving the durability of concrete.

[0024] Since hydrotalcite, as an inorganic substance, has strong hydrophilicity, it has poor dispersion when mixed with polyurethane. Vinyl prepolymer has unique hydrophilicity. This hydrophilic property enables the vinyl prepolymer to be adsorbed on the surface of hydrotalcite particles, forming a coating layer, which reduces direct contact between hydrotalcite particles and thus reduces the possibility of hydrotalcite agglomeration.

[0025] 2. 2-Acrylamido-2-methylpropanesulfonic acid contains sulfonic acid groups, which can interact with the metal ions of hydrotalcite. Acrylic acid contains carboxyl groups, which can also interact with the surface of hydrotalcite. Sodium p-styrenesulfonate contains benzene rings and sulfonic acid groups. The benzene rings provide hydrophobicity, and the sulfonic acid groups provide hydrophilicity, which help regulate the interfacial interaction between the prepolymer and hydrotalcite. Diallylammonium chloride is a cationic monomer that can neutralize the negative charges on the surface of hydrotalcite, reducing the electrostatic attraction between particles and thus improving dispersibility. The macromolecular chains formed by polymerization of acrylamide can provide steric hindrance, thereby reducing the agglomeration of hydrotalcite particles.

[0026] 3. Since concrete is mainly composed of inorganic materials such as cement, sand, gravel and water, these materials do not contain organic combustible substances under normal conditions, so they are not easy to burn and have good flame retardant properties. Polyurethane contains a large amount of carbon and hydrogen atoms. During the combustion process, these carbon and hydrogen atoms easily react chemically with oxygen, thereby releasing heat and combustible gases, accelerating the combustion process, and thus causing the overall flame retardant properties of concrete to decline.

[0027] Triaminomethylphosphine oxide contains phosphorus, which can form phosphoric acid or its derivatives during combustion. These substances can act as an acid source to promote carbonization, forming a carbon layer to isolate oxygen and heat, thereby preventing further combustion. Since hexachlorocyclotriphosphazene and melamine can form a polyphosphazene structure, the polyphosphazene structure formed by hexachlorocyclotriphosphazene and melamine is rich in P and N elements, which can also improve the flame retardant properties of triaminomethylphosphine oxide. Hexachlorocyclotriphosphazene contains multiple chlorine atoms and phosphorus atoms, which can absorb ultraviolet energy. Melamine itself has a certain ultraviolet light stabilization effect. Therefore, the addition of modified phosphide can not only improve the ultraviolet resistance of the modified polyurethane, but also improve the flame retardant properties of the polyurethane. DETAILED DESCRIPTION

[0028] The present application is further described in detail below in conjunction with Examples 1-14 and Comparative Examples 1-3.

[0029] raw material

[0030] Minerals: Suzhou Gangsong Building Materials Co., Ltd.; Polyurethane: Shenyang Yilepux Chemical Co., Ltd.; Hydrotalcite: CAS: 12304-65-3; 2-Acrylamido-2-methylpropanesulfonic acid: CAS: 15214-89-8; Acrylic acid: CAS: 79-10-7; Sodium p-styrenesulfonate: CAS: 2695-37-6; Deionized water: CAS: 7732-18-5; Sodium hydroxide: CAS: 1310-73-2; Diallyldimethylammonium chloride: CAS: 7398-69-8; Propylene Amide CAS: 79-06-1; Ammonium persulfate CAS: 7727-54-0; Sodium bisulfite CAS: 7631-90-5; Nitrogen CAS: 7727-37-9; Anhydrous ethanol CAS: 64-17-5; Triaminomethylphosphine oxide CAS: 545-55-1; Hexachlorocyclotriphosphazene CAS: 940-71-6; Melamine CAS: 108-78-1; N,N-Dimethylformamide CAS: 68-12-2; Triethylamine CAS: 121-44-8.

[0031] Example

[0032] Example 1

[0033] A low-temperature resistant and crack-resistant concrete comprises the following raw materials: 100g of mineral material and 6g of modified polyurethane.

[0034] Specifically, the preparation method of low temperature resistant and crack resistant concrete includes the following steps:

[0035] S1: Weigh 2 g of triaminomethylphosphine oxide and disperse it in 20 ml of N,N-dimethylformamide. Place the mixture in an ice bath and stir. Weigh 1.5 g of hexachlorocyclotriphosphazene and add it to a beaker. Ultrasonic disperse the mixture with 10 ml of N,N-dimethylformamide and then add the mixture dropwise to the triaminomethylphosphine oxide dispersion. After the addition is complete, continue the reaction for 20 minutes to obtain dispersion 1.

[0036] S2: Weigh 1 g of melamine into a beaker, disperse it with 20 ml of N,N-dimethylformamide by ultrasonication, and then add it dropwise to the dispersion 1 in S1 to obtain dispersion 2;

[0037] S3: Weigh 5 ml of triethylamine and continue to add it dropwise to the dispersion 2 of S2. After the addition is complete, continue the reaction for 30 minutes to obtain dispersion 3. Pour the evenly stirred dispersion 3 into an autoclave and react at 120°C for 26 hours. Then, centrifuge at a high speed. Then, dry the product in an oven at 80°C for 5 hours and grind it into powder to obtain the modified phosphide.

[0038] S4: Weigh 2.5 g of 2-acrylamido-2-methylpropanesulfonic acid, 1.3 g of acrylic acid, 0.7 g of sodium p-styrenesulfonate, and 0.18 g of modified phosphide into a beaker, add 20 ml of deionized water to dissolve, add 30% sodium hydroxide aqueous solution dropwise until the solution pH = 7, then add 1 g of dimethyldiallylammonium chloride, 3.4 g of acrylamide, and 0.05 g of initiator, stir evenly to completely dissolve all monomers, pass nitrogen for 10 min, seal with plastic wrap, place in a constant temperature water bath at 50°C, react for 6 h, wash with anhydrous ethanol, and then shear and granulate to obtain a vinyl prepolymer;

[0039] Wherein, the initiator includes 0.03g ammonium persulfate and 0.02g sodium bisulfite;

[0040] S5: Weigh 2.5 g of hydrotalcite and 0.6 g of vinyl prepolymer and mix them evenly. Dry them in an oven at 80°C for 8 h, extrude them into pellets on an extruder at 230°C, and then injection mold them to obtain modified hydrotalcite.

[0041] S6: adding 1.5 g of modified hydrotalcite to 6 g of polyurethane and stirring evenly, and then placing the mixture into a high-speed shearing machine for shearing to obtain modified polyurethane;

[0042] S7: Weigh 100 g of mineral material, place it at 25° C., and mix it with 6 g of modified polyurethane according to a conventional method to obtain low-temperature resistant and crack-resistant concrete.

[0043] Example 2-3

[0044] The difference from Example 1 is that the addition amount of each component of the low-temperature resistant and crack-resistant concrete is different, as shown in Table 1.

[0045] Table 1 Addition amount of each component of low temperature resistant and crack resistant concrete in Examples 1-3 (g)

[0046]

[0047] Example 4

[0048] The difference from Example 1 is that the modified hydrotalcite is replaced by an equal amount of carbon black.

[0049] Example 5

[0050] The difference from Example 1 is that the modified phosphide is replaced by an equal amount of triaminomethylphosphine oxide.

[0051] Example 6

[0052] The difference from Example 1 is that no modified phosphide is added.

[0053] Examples 7-8

[0054] The difference from Example 1 is that the addition amount of each component of the modified phosphide is different, as shown in Table 2.

[0055] Table 2 Addition amount of each component of modified phosphide in Example 1 and Examples 7-8

[0056]

[0057] Examples 9-10

[0058] The difference from Example 1 is that the addition amounts of the components of the vinyl prepolymer are different, as shown in Table 3.

[0059] Table 3 Addition amount of each component of vinyl prepolymer in Example 1 and Examples 9-10

[0060]

[0061] Examples 11-12

[0062] The difference from Example 1 is that the addition amount of each component of the modified hydrotalcite is different, as shown in Table 4.

[0063] Table 4 Addition amount of each component of modified hydrotalcite in Example 1 and Examples 11-12 (g)

[0064]

[0065] Examples 13-14

[0066] The difference from Example 1 is that the addition amount of each component of the modified polyurethane is different, as shown in Table 5.

[0067] Table 5 Addition amount of each component of modified polyurethane in Example 1 and Examples 13-14 (g)

[0068]

[0069] Comparative Example

[0070] Comparative Example 1

[0071] The difference from Example 1 is that no vinyl prepolymer is added.

[0072] Comparative Example 2

[0073] The difference from Example 1 is that no modified hydrotalcite is added.

[0074] Comparative Example 3

[0075] The difference from Example 1 is that no modified polyurethane is added.

[0076] Performance testing

[0077] Detection method

[0078] 1. Durability test

[0079] Three samples were taken from each of Examples 1-14 and Comparative Examples 1-3. The electric flux, chloride ion diffusion coefficient, and carbonation depth of the concrete were measured in accordance with GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete". The sample size was 100 mm × 100 mm × 100 mm, and durability testing was performed.

[0080] The test data is shown in Table 6.

[0081] Table 6 Durability test table of Examples 1-14 and Comparative Examples 1-3

[0082]

[0083] Combining Example 1 and Comparative Example 1 and Table 6, it can be seen that compared with Example 1, the electric flux and chloride ion diffusion coefficient of Comparative Example 1 after 28 days of sample curing are greatly increased, which shows that the addition of vinyl prepolymer can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0084] The reason is that vinyl prepolymer has unique hydrophilicity. This hydrophilic property enables vinyl prepolymer to be adsorbed on the surface of hydrotalcite particles, forming a coating layer, which reduces direct contact between hydrotalcite particles and thus reduces the possibility of hydrotalcite agglomeration. Therefore, hydrotalcite and polyurethane can be better mixed, thereby improving the anti-aging properties of polyurethane and thus improving the durability of concrete.

[0085] Combining Example 1 and Comparative Example 2 with Table 6, it can be seen that compared with Example 1, the electric flux and chloride ion diffusion coefficient of Comparative Example 2 after 28 days of curing also increased significantly, indicating that the addition of modified hydrotalcite can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0086] The reason is that the modified hydrotalcite has a layered structure, consisting of two layers of positively charged metal hydroxide layers and a layer of negatively charged interlayer anions. The interlayer anions can absorb ultraviolet rays, thereby reducing the damage of ultraviolet rays to polyurethane. The anti-aging properties of polyurethane are also improved, thereby improving the durability of concrete.

[0087] Combining Example 1 and Comparative Example 3 with Table 6, it can be seen that compared with Example 1, the electric flux and chloride ion diffusion coefficient of Comparative Example 3 after 28 days of sample curing also increased significantly. This shows that compared with conventional concrete, the addition of modified polyurethane can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0088] Combining Example 1 and Examples 2-3 with Table 6, it can be seen that, compared with Example 1, the electric flux and chloride ion diffusion coefficient of the samples of Example 2 and Example 3 increased after 28 days of sample curing. This shows that the addition amount of each component of the low-temperature resistant and crack-resistant concrete affects the durability of the low-temperature resistant and crack-resistant concrete to a certain extent.

[0089] Combining Example 1 and Example 4 with Table 6, it can be seen that, compared with Example 1, the electric flux and chloride ion diffusion coefficient of the sample in Example 4 increased significantly after 28 days of curing. This shows that, compared with the addition of carbon black, the addition of modified hydrotalcite can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0090] Combining Example 1 and Example 5 and Table 6, it can be seen that, compared with Example 1, the electric flux and chloride ion diffusion coefficient of the sample in Example 5 increased significantly after 28 days of sample curing. This shows that, compared with the addition of triaminomethylphosphine oxide alone, the addition of modified phosphide can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0091] Combining Example 1 and Example 6 and Table 6, it can be seen that, compared with Example 1, the electric flux and chloride ion diffusion coefficient of the sample in Example 6 increased significantly after 28 days of sample curing. This shows that, compared with not adding modified phosphide, adding modified phosphide can effectively improve the durability of low-temperature resistant and crack-resistant concrete.

[0092] Combining Example 1 with Examples 7-8 and Table 6, it can be seen that, relative to Example 1, the electric flux and chloride ion diffusion coefficient of the samples of Examples 7 and 8 increased slightly after 28 days of curing. This indicates that the addition amount of each component of the modified phosphide affects the durability of the low-temperature resistant and crack-resistant concrete.

[0093] Combining Example 1 with Examples 9-10 and Table 6, it can be seen that, relative to Example 1, the electric flux and chloride ion diffusion coefficient of the samples of Examples 9 and 10 increased slightly after 28 days of curing. This indicates that the addition amount of each component of the vinyl prepolymer affects the durability of the low-temperature resistant and crack-resistant concrete.

[0094] Combining Example 1 with Examples 11-12 and Table 6, it can be seen that, relative to Example 1, the electric flux and chloride ion diffusion coefficient of the samples of Examples 11 and 12 increased slightly after 28 days of curing. This indicates that the addition amount of each component of the modified hydrotalcite affects the durability of the low-temperature-resistant and crack-resistant concrete.

[0095] Combining Example 1 and Examples 13-14 with Table 6, it can be seen that, relative to Example 1, the electric flux and chloride ion diffusion coefficient of the samples of Example 13 and Example 14 increased slightly after 28 days of curing. This shows that the addition amount of each component of the modified polyurethane affects the durability of the low-temperature resistant and crack-resistant concrete.

[0096] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low temperature resistant and crack resistant concrete, characterized in that: The method comprises the following raw materials in parts by weight: 95-105 parts of mineral material and 3-9 parts of modified polyurethane; The modified polyurethane comprises the following raw materials in parts by mass: 4-8 parts of polyurethane and 1.3-1.7 parts of modified hydrotalcite; The modified hydrotalcite comprises the following raw materials in parts by weight: 2.1-2.9 parts of hydrotalcite and 0.4-0.8 parts of vinyl prepolymer; The vinyl prepolymer comprises the following raw materials in parts by mass: 1.5-3.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1-1.6 parts of acrylic acid, 0.5-0.9 parts of sodium p-styrenesulfonate, 0.5-1.5 parts of dimethyldiallylammonium chloride, 3-3.8 parts of acrylamide, 0.02-0.08 parts of initiator and 0.15-0.21 parts of modified phosphide; The preparation method of the vinyl prepolymer comprises the following steps: weighing 1.5-3.5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 1-1.6 parts of acrylic acid, 0.5-0.9 parts of sodium p-styrenesulfonate and 0.15-0.21 parts of modified phosphide into a beaker, adding 15-25 ml of deionized water for dissolution, adjusting the pH value, then adding 0.5-1.5 parts of dimethyldiallylammonium chloride, 3-3.8 parts of acrylamide and 0.02-0.08 parts of initiator, stirring evenly to completely dissolve all monomers, passing nitrogen for 5-15 minutes, placing in a constant temperature water bath at 45-55° C., reacting for 4-8 hours, washing with anhydrous ethanol and then shearing and granulating.

2. The low temperature resistant and crack resistant concrete according to claim 1, characterized in that: The modified phosphide comprises the following raw materials: 1-3g of triaminomethylphosphine oxide, 1-2g of hexachlorocyclotriphosphazene, 0.5-1.5g of melamine, 35-65ml of N,N-dimethylformamide, and 2-8ml of triethylamine.

3. The low temperature resistant and crack resistant concrete according to claim 2, characterized in that: The preparation method of the modified phosphide comprises the following steps: weighing 1-3 g of triamine methylphosphine oxide, dispersing the mixture in 15-25 ml of N, N-dimethylformamide, and placing the mixture in an ice bath for stirring; weighing 1-2 g of hexachlorocyclotriphosphazene, adding the mixture to a beaker, ultrasonically dispersing the mixture with 5-15 ml of N, N-dimethylformamide, and then dropwise adding the mixture to the triamine methylphosphine oxide dispersion; after the addition is complete, continuing the reaction for 25-35 minutes to obtain a dispersion solution 1; weighing 0.5-1.5 g of melamine, adding the mixture to a beaker, and adding the mixture to a beaker with 15-25 ml of N, N-dimethylformamide; After ultrasonic dispersion, N,N-dimethylformamide is added dropwise to the above dispersion liquid 1 to obtain dispersion liquid 2. 2-8 ml of triethylamine is continued to be added dropwise to the above dispersion liquid 2. After the addition is completed, the reaction is continued for 25-35 minutes to obtain dispersion liquid 3. The evenly stirred dispersion liquid 3 is poured into a high-pressure reactor and reacted at 100-140°C for 24-28 hours. The mixture is then centrifuged at a high speed. The product is then dried at 75-85°C for 2-8 hours and ground into powder.

4. The low temperature resistant and crack resistant concrete according to claim 3, characterized in that: The preparation method of the modified hydrotalcite comprises the following steps: weighing 2.1-2.9 parts of hydrotalcite and 0.4-0.8 parts of vinyl prepolymer, mixing them uniformly, drying them in an oven at 75-85° C. for 6-10 hours, extruding them into granules at 210-250° C. on an extruder, and injection molding them.

5. The low temperature resistant and crack resistant concrete according to claim 4, characterized in that: The preparation method of the modified polyurethane comprises the following steps: adding 1.3-1.7 parts of modified hydrotalcite to 4-8 parts of polyurethane, stirring the mixture evenly, and then placing the mixture into a high-speed shearing machine for shearing.

6. The method for preparing low-temperature resistant and crack-resistant concrete according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: weighing 95-105 parts of mineral materials, placing the materials at 20-30 DEG C, and mixing the materials with 3-9 parts of modified polyurethane to form a uniform mixture.

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