Anti-crack concrete and preparation method thereof

Abstract

The invention discloses anti-crack concrete and a preparation method thereof, and belongs to the field of concrete materials. The concrete is prepared from the following raw materials: cement, medium sand, gravel, fly ash, ion exchange silica fume, basalt fiber with the surface modified by fluoride, a water reducing agent and water. The concrete disclosed by the invention has relatively good durability in a humid and hot environment, and after a concrete sample is placed in a constant-temperature and constant-humidity environment with the temperature being 85 DEG C and the relative humidity being 85% for 1512 hours, the compressive strength is 45.9-46.4 MPa, the axial tensile strength is 6.8-7.0 MPa, and the splitting tensile strength is 7.5-7.6 MPa.

Description

Technical Field

[0001] The invention relates to crack-resistant concrete and a preparation method thereof, and belongs to the field of concrete materials. Background Art

[0002] Concrete cracking is the comprehensive result of concrete's own performance and the influence of the external environment. Concrete cracks caused by itself can be divided into "plastic cracks" and "stress cracks". Plastic cracks are caused by the plastic shrinkage of concrete and occur in the plastic stage of concrete. They are shrinkage cracks. Stress cracks are caused by the tensile stress generated in the concrete at a certain moment due to chemical shrinkage, drying shrinkage, cooling shrinkage, and alkali-aggregate reaction inside the concrete, which exceeds the tensile strength of the concrete at that time, resulting in cracks.

[0003] The core principle of concrete crack resistance is to form crack resistance from the material level by actively controlling the balance between shrinkage stress and tensile strength. Common methods include fiber reinforcement, chemical compensation for shrinkage, hydration heat regulation, and interface strengthening.

[0004] Among them, the expansion agent has limitations in improving the anti-cracking performance. The expansion effect of calcium sulfoaluminate depends on the formation of ettringite, which requires sufficient water and suitable temperature (30-40℃ is best). If the maintenance humidity is insufficient or the temperature is too high, the formation of ettringite will be hindered or even decomposed, resulting in expansion failure. For example, the internal temperature of a concrete structure with a thickness of more than 2m can reach more than 70℃, at which time the expansion agent can hardly play a role. In addition, the compounding and dosage of the expansion agent need to be precisely controlled, which makes construction difficult and the price is high.

[0005] Fiber reinforcement technology can greatly improve the crack resistance of concrete, and can greatly improve its crack resistance at a lower dosage. The commonly used fibers in fiber reinforcement technology are steel fiber, polypropylene fiber, and basalt fiber. All three fibers can improve the crack resistance of concrete by more than 30%. Among them, steel fiber and polypropylene fiber have lower costs, but their corrosion resistance is poor, and the prepared concrete has low durability in corrosive environments. Basalt fiber can keep the improvement of concrete's crack resistance performance above 40% in corrosive environments, and is the first choice in corrosive environments.

[0006] Studies have shown that micro cracks are easily formed on the fiber surface during the production process of basalt fiber, which may expand into macro cracks during long-term use, affecting durability. Experiments have found that untreated basalt fiber can cause concrete to lose strength in a hot and humid environment, which can be as much as 15-20%.

[0007] In summary, in the prior art solution of using fiber reinforcement technology to improve the crack resistance of concrete, basalt fiber can improve the crack resistance of concrete while maintaining high durability in a corrosive environment, but it will cause the strength of concrete to decrease in a hot and humid environment. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the prior art by specially treating the basalt fiber that enhances the crack resistance of concrete, and then optimizing the composition and proportion of the gel component through specially treated silica fume, thereby improving the crack resistance of concrete in a corrosive environment and reducing the strength loss of concrete in a hot and humid environment.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions: A crack-resistant concrete, wherein the raw material components of the concrete include cement, medium sand, crushed stone, fly ash, ion-exchanged silica fume, basalt fiber modified with surface fluoride, a water reducer and water, and the mass ratio of the components is 110-130:150-200:310-360:14-16:40-50:11-13:2.5-3.5:70-80.

[0010] The following are further improvements to the above technical solution: The cement is ordinary Portland cement with a strength grade of P·O42.5; The medium sand is machine-made sand with a bulk density of 1517 kg / m 3 ; The crushed stone is 5-25mm continuous gradation, and the bulk density is 1552kg / m 3 ; The fly ash is Class II Class C fly ash; The water reducer is a polycarboxylate water reducer, model number is PC-1007; The preparation method of the surface fluoride-modified basalt fiber is as follows: The basalt fiber is immersed in a 0.45-0.55 mol / L hydrochloric acid solution for surface activation, and the immersion time is 110-130 minutes. After the immersion is completed, it is washed and dried to obtain the surface-activated basalt fiber. Polyvinylidene fluoride and dimethylacetamide are mixed, and the polyvinylidene fluoride is completely dissolved by heating to 70°C to obtain a polyvinylidene fluoride solution, and then the surface-activated basalt fiber is added thereto, and the solution is stirred at a temperature of 5.5-6.5 hours. After the stirring is completed, the solvent is evaporated at 165°C, and then the temperature is controlled to be 575-625°C for calcination, and the calcination time is 85-100 minutes. After the calcination is completed, the surface fluoride-modified basalt fiber is obtained; The mass ratio of the basalt fiber to the hydrochloric acid solution is 1:6.5-7.5; The basalt fiber has a diameter of 7-9 μm, a length of 7.0-8.0 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%; The mass ratio of the polyvinylidene fluoride, dimethylacetamide and surface activated basalt fiber is 9-11:100-150:40-50; The molecular weight of the polyvinylidene fluoride is 1.1-1.5×10 5 g / mol.

[0011] The preparation method of the ion exchange silica fume is: The silica fume is mixed with a saturated aluminum chloride solution and stirred for 25-35 minutes, and then allowed to stand for 3.5-4.5 hours. After the standing is completed, the filtered solid is calcined at 710-730°C for 80-100 minutes. After the calcination is completed, ion exchange silica fume is obtained; The mass ratio of the silica fume to the saturated aluminum chloride solution is 1:14-16; The particle size of the silica fume is 0.11 μm, the silicon dioxide content is 85.2%, and the specific surface area is 27355 m 2 / kg.

[0012] The preparation method of the crack-resistant concrete is: The raw material components of a specified mass are mixed uniformly and subjected to standard curing to obtain a crack-resistant concrete.

[0013] Compared with the prior art, the present invention achieves the following beneficial effects: The concrete of the present invention has high strength. The compressive strength and flexural strength of the concrete are tested according to the method in GB / T50081-2019. The compressive strength is 52.2-52.7MPa, and the flexural strength is 19.1-19.4MPa. The concrete of the present invention has excellent crack resistance. According to the method in GB / T50081-2019, the axial tensile strength and splitting tensile strength of the concrete are tested. According to the method in GB / T50082-2024, the cracking area of ​​each crack in the concrete and the number of cracks per unit area are tested. The axial tensile strength is 7.5-7.7 MPa, the splitting tensile strength is 8.4-8.7 MPa, and the cracking area of ​​each crack in the concrete is 0.14-0.18 mm 2 / line, the number of cracks per unit area is 3-5 / m 2 ; The concrete of the present invention has good durability in a corrosive environment. According to the method in GB / T50082-2024, the concrete is subjected to a dry-wet cycle, and the medium used in the dry-wet cycle is 5% Na 2 SO 4Solution, the number of dry-wet cycles is 150 times, the axial tensile strength and splitting tensile strength of the concrete are tested after 150 dry-wet cycles. The axial tensile strength after 150 dry-wet cycles is 7.2-7.4MPa, and the splitting tensile strength is 8.2-8.4MPa; The concrete of the present invention has good durability in a hot and humid environment. The concrete sample is placed in a constant temperature and humidity environment with a temperature of 85°C and a relative humidity of 85%. After being placed for 504 hours, the compressive strength is 51.3-51.6MPa, the axial tensile strength is 7.3-7.5MPa, and the splitting tensile strength is 8.2-8.4MPa. After being placed for 1008 hours, the compressive strength is 48.2-48.8MPa, the axial tensile strength is 7.1-7.2MPa, and the splitting tensile strength is 7.8-8.0MPa. After being placed for 1512 hours, the compressive strength is 45.9-46.4MPa, the axial tensile strength is 6.8-7.0MPa, and the splitting tensile strength is 7.5-7.6MPa. DETAILED DESCRIPTION Example 1

[0014] A crack-resistant concrete, whose raw material components include cement, medium sand, crushed stone, fly ash, ion-exchanged silica fume, basalt fiber modified with surface fluoride, water reducing agent, and water, and the mass ratio of the components is 120:175:335:15:45:12:3:75; The cement is ordinary Portland cement with a strength grade of P·O42.5; The medium sand is machine-made sand with a bulk density of 1517 kg / m 3 ; The crushed stone is 5-25mm continuous gradation, and the bulk density is 1552kg / m 3 ; The fly ash is Class II Class C fly ash; The water reducer is a polycarboxylate water reducer, model number is PC-1007; The preparation method of the surface fluoride-modified basalt fiber is as follows: The basalt fiber is immersed in a 0.5 mol / L hydrochloric acid solution for surface activation. The immersion time is 120 minutes. After the immersion is completed, it is washed and dried to obtain the surface-activated basalt fiber. Polyvinylidene fluoride and dimethylacetamide are mixed, and the mixture is heated to 70°C to completely dissolve the polyvinylidene fluoride to obtain a polyvinylidene fluoride solution. The surface-activated basalt fiber is then added thereto, and the mixture is stirred at a temperature of 6 hours. After the stirring is completed, the solvent is evaporated at 165°C, and then the temperature is controlled to be 600°C for calcination. The calcination time is 90 minutes. After the calcination is completed, the surface fluoride-modified basalt fiber is obtained. The mass ratio of the basalt fiber to the hydrochloric acid solution is 1:7; The basalt fiber has a diameter of 8 μm, a length of 7.5 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%; The mass ratio of the polyvinylidene fluoride, dimethylacetamide and surface activated basalt fiber is 10:125:45; The molecular weight of the polyvinylidene fluoride is 1.3×10 5 g / mol.

[0015] The preparation method of the ion exchange silica fume is: The silica fume and the saturated aluminum chloride solution were mixed and stirred for 30 minutes, and then allowed to stand for 4 hours. After the standing was completed, the filtered solid was calcined at 720°C for 90 minutes. After the calcination was completed, ion exchange silica fume was obtained; The mass ratio of the silica fume to the saturated aluminum chloride solution is 1:15; The particle size of the silica fume is 0.11 μm, the silicon dioxide content is 85.2%, and the specific surface area is 27355 m 2 / kg.

[0016] The preparation method of the crack-resistant concrete is: The raw material components of a specified mass are mixed uniformly and subjected to standard curing to obtain a crack-resistant concrete. Example 2

[0017] A crack-resistant concrete, whose raw material components include cement, medium sand, crushed stone, fly ash, ion-exchanged silica fume, basalt fiber modified with surface fluoride, water reducing agent, and water, and the mass ratio of the components is 110:150:310:14:40:11:2.5:70; The cement is ordinary Portland cement with a strength grade of P·O42.5; The medium sand is machine-made sand with a bulk density of 1517 kg / m 3 ; The crushed stone is 5-25mm continuous gradation, and the bulk density is 1552kg / m 3 ; The fly ash is Class II Class C fly ash; The water reducer is a polycarboxylate water reducer, model number is PC-1007; The preparation method of the surface fluoride-modified basalt fiber is as follows: The basalt fiber was immersed in a 0.45 mol / L hydrochloric acid solution for surface activation. The immersion time was 110 min. After the immersion was completed, it was washed and dried to obtain the surface activated basalt fiber. Polyvinylidene fluoride and dimethylacetamide were mixed and heated to 70°C to completely dissolve the polyvinylidene fluoride to obtain a polyvinylidene fluoride solution. Then, the surface activated basalt fiber was added thereto, and the mixture was stirred at a temperature of 5.5 h. After the stirring was completed, the solvent was evaporated at 165°C. Then, the temperature was controlled to be 575°C for calcination. The calcination time was 100 min. After the calcination was completed, the surface fluoride-modified basalt fiber was obtained. The mass ratio of the basalt fiber to the hydrochloric acid solution is 1:7.5; The basalt fiber has a diameter of 7 μm, a length of 8.0 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%; The mass ratio of the polyvinylidene fluoride, dimethylacetamide and surface activated basalt fiber is 9:100:40; The molecular weight of the polyvinylidene fluoride is 1.1×10 5 g / mol.

[0018] The preparation method of the ion exchange silica fume is: The silica fume and the saturated aluminum chloride solution were mixed and stirred for 25 minutes, and then allowed to stand for 4.5 hours. After the standing was completed, the filtered solid was calcined at 710°C for 100 minutes. After the calcination was completed, ion exchange silica fume was obtained; The mass ratio of the silica fume to the saturated aluminum chloride solution is 1:14; The particle size of the silica fume is 0.11 μm, the silicon dioxide content is 85.2%, and the specific surface area is 27355 m 2 / kg.

[0019] The preparation method of the crack-resistant concrete is: The raw material components of a specified mass are mixed uniformly and subjected to standard curing to obtain a crack-resistant concrete. Example 3

[0020] A crack-resistant concrete, whose raw material components include cement, medium sand, crushed stone, fly ash, ion-exchanged silica fume, basalt fiber modified with surface fluoride, water reducing agent, and water, and the mass ratio of the components is 130:200:360:16:50:13:3.5:80; The cement is ordinary Portland cement with a strength grade of P·O42.5; The medium sand is machine-made sand with a bulk density of 1517 kg / m 3 ; The crushed stone is 5-25mm continuous gradation, and the bulk density is 1552kg / m 3 ; The fly ash is Class II Class C fly ash; The water reducer is a polycarboxylate water reducer, model number is PC-1007; The preparation method of the surface fluoride-modified basalt fiber is as follows: The basalt fiber is immersed in a 0.55 mol / L hydrochloric acid solution for surface activation. The immersion time is 130 minutes. After the immersion is completed, it is washed and dried to obtain the surface-activated basalt fiber. Polyvinylidene fluoride and dimethylacetamide are mixed, and the mixture is heated to 70°C to completely dissolve the polyvinylidene fluoride to obtain a polyvinylidene fluoride solution. The surface-activated basalt fiber is then added thereto, and the mixture is stirred at a temperature of 6.5 hours. After the stirring is completed, the solvent is evaporated at 165°C, and then the temperature is controlled to be 625°C for calcination. The calcination time is 85 minutes. After the calcination is completed, the surface-fluoride-modified basalt fiber is obtained. The mass ratio of the basalt fiber to the hydrochloric acid solution is 1:6.5; The basalt fiber has a diameter of 9 μm, a length of 7.0 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%; The mass ratio of the polyvinylidene fluoride, dimethylacetamide and surface activated basalt fiber is 11:150:50; The molecular weight of the polyvinylidene fluoride is 1.5×10 5 g / mol.

[0021] The preparation method of the ion exchange silica fume is: The silica fume and the saturated aluminum chloride solution were mixed and stirred for 35 minutes, and then allowed to stand for 3.5 hours. After the standing, the solid was filtered and calcined at 730°C for 80 minutes. After the calcination, ion exchange silica fume was obtained. The mass ratio of the silica fume to the saturated aluminum chloride solution is 1:16; The particle size of the silica fume is 0.11 μm, the silicon dioxide content is 85.2%, and the specific surface area is 27355 m 2 / kg.

[0022] The preparation method of the crack-resistant concrete is: The raw material components of a specified mass are mixed uniformly and subjected to standard curing to obtain a crack-resistant concrete.

[0023] Comparative Example 1 Different from Example 1, untreated basalt fibers are used as raw material components of concrete instead of basalt fibers modified with surface fluoride, and the amount is kept unchanged to prepare concrete; The untreated basalt fiber has a diameter of 8 μm, a length of 7.5 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%.

[0024] Comparative Example 2 Different from Example 1, untreated silica fume is used instead of ion-exchanged silica fume as a raw material component of concrete, and the amount is kept unchanged to prepare concrete; The untreated silica fume has a particle size of 0.11 μm, a silicon dioxide content of 85.2%, and a specific surface area of ​​27355 m 2 / kg.

[0025] Test Example 1 Strength Test The compressive strength and flexural strength of the concrete of Examples 1-3 and Comparative Examples 1-2 were tested according to the method in GB / T50081-2019. The results are shown in Table 1.

[0026] Table 1

[0027] In Example 1-3, by specially treating the basalt fiber that enhances the crack resistance of concrete, and then optimizing the composition and proportion of the gel component by specially treated silica fume, the mechanical properties of concrete can be improved, and both the compressive strength and the flexural strength are relatively high; Comparative Example 1 uses untreated basalt fiber instead of surface fluoride-modified basalt fiber as the raw material component of concrete, which will cause the mechanical properties of concrete to decrease, among which the decrease in flexural strength is more serious, and the compressive strength will also decrease to a certain extent; Comparative Example 2 uses untreated silica fume instead of ion exchange silica fume as a raw material component of concrete, which will cause the mechanical properties of concrete to decrease, among which the compressive strength decreases more seriously, and the flexural strength also decreases to a certain extent.

[0028] Test Example 2: Crack resistance test The concrete of Examples 1-3 and Comparative Examples 1-2 was tested for axial tensile strength and splitting tensile strength according to the method in GB / T50081-2019, and the crack area of ​​each crack in the concrete and the number of cracks per unit area were tested according to the method in GB / T50082-2024. The results are shown in Table 2.

[0029] Table 2

[0030] In Example 1-3, the basalt fiber for enhancing the crack resistance of concrete is specially treated, and the composition and proportion of the gel component are optimized by using specially treated silica fume, so that the crack resistance of concrete can be improved, the axial tensile strength and the splitting tensile strength are both high, the number of cracks is small, and the crack area is also small; Comparative Example 1 uses untreated basalt fiber instead of surface fluoride-modified basalt fiber as a raw material component of concrete, which will cause the crack resistance of concrete to decrease, the decrease of tensile strength and splitting tensile strength are more serious, the area of ​​cracks increases seriously, and the increase degree of the number of cracks is slightly higher; Comparative Example 2 uses untreated silica fume instead of ion exchange silica fume as the raw material component of concrete, which will cause the mechanical properties of concrete to decline, and the crack resistance of concrete to decline. Both the tensile strength and the splitting tensile strength will decrease to a large extent, the area of ​​the cracks will increase to a certain extent, and the number of cracks will increase seriously.

[0031] Test Example 3 Performance test in a corrosive environment The concrete of Example 1-3 and Comparative Example 1-2 was subjected to dry-wet cycle according to the method in GB / T50082-2024, and the medium used in the dry-wet cycle was 5% Na 2 SO 4 Solution, the number of dry-wet cycles is 150 times, and the axial tensile strength and splitting tensile strength of the concrete are tested after 150 dry-wet cycles. The results are shown in Table 3.

[0032] Table 3

[0033] In Example 1-3, by specially treating the basalt fiber that enhances the crack resistance of concrete, and then optimizing the composition and proportion of the gel component through specially treated silica fume, the durability of concrete in a corrosive environment can be improved, and high axial tensile strength and splitting tensile strength can still be maintained after dry-wet cycles; Comparative Example 1 uses untreated basalt fibers instead of surface fluoride-modified basalt fibers as the raw material component of concrete, which will cause the durability of concrete in a corrosive environment to decrease, and the axial tensile strength and splitting tensile strength to decrease more seriously; Comparative Example 2 uses untreated silica fume instead of ion-exchanged silica fume as a raw material component of concrete, which will cause the durability of concrete in a corrosive environment to decrease, and the axial tensile strength and splitting tensile strength will both decrease to a certain extent.

[0034] Test Example 4 Performance test in hot and humid environment The durability test of the concrete of Examples 1-3 and Comparative Examples 1-2 in a hot and humid environment was carried out. The concrete samples were placed in a constant temperature and humidity environment with a temperature of 85°C and a relative humidity of 85%. The placement time was 504h, 1008h, and 1512h, respectively. The performance changes of different samples after different placement time were tested, including the tests of compressive strength, axial tensile strength, and splitting tensile strength. The results are shown in Table 4.

[0035] Table 4

[0036] In Example 1-3, by specially treating the basalt fiber that enhances the crack resistance of concrete, and then optimizing the composition and proportion of the gel component by specially treated silica fume, the durability of concrete in a hot and humid environment can be improved, and high compressive strength, axial tensile strength, and splitting tensile strength can be maintained in a hot and humid environment for a long time; Comparative Example 1 uses untreated basalt fiber instead of surface fluoride-modified basalt fiber as a raw material component of concrete, which will cause the durability of concrete in a hot and humid environment to decrease. In a long-term hot and humid environment, the decrease in compressive strength is relatively low, while the decrease in axial tensile strength and splitting tensile strength is more serious; Comparative Example 2 uses untreated silica fume instead of ion exchange silica fume as a raw material component of concrete, which will cause the durability of concrete in a hot and humid environment to decrease. In a hot and humid environment for a long time, the compressive strength will decrease more seriously, and the axial tensile strength and splitting tensile strength will decrease to a certain extent.

Claims

1. A crack-resistant concrete, characterized in that: The raw materials of the concrete include cement, medium sand, crushed stone, fly ash, ion exchange silica fume, basalt fiber modified with surface fluoride, water reducing agent and water; The preparation method of the surface fluoride-modified basalt fiber is as follows: The basalt fiber is immersed in a hydrochloric acid solution for surface activation. After the immersion is completed, the basalt fiber is washed and dried to obtain the surface activated basalt fiber. Polyvinylidene fluoride and dimethylacetamide are mixed and heated to completely dissolve the polyvinylidene fluoride to obtain a polyvinylidene fluoride solution. The surface activated basalt fiber is then added thereto, and the mixture is stirred and heated. After the stirring is completed, the solvent is evaporated, and then calcined. After the calcination is completed, the basalt fiber with surface fluoride modified is obtained. The preparation method of the ion exchange silica fume is: The silica fume is mixed with a saturated aluminum chloride solution and stirred, and then allowed to stand after stirring. After the standing is completed, the mixture is filtered, and the filtered solid is calcined to obtain ion exchange silica fume.

2. The crack-resistant concrete according to claim 1, characterized in that: The raw materials of the concrete include cement, medium sand, crushed stone, fly ash, ion exchange silica fume, basalt fiber modified with surface fluoride, water reducing agent and water in a mass ratio of 110-130:150-200:310-360:14-16:40-50:11-13:2.5-3.5:70-80; The cement is ordinary Portland cement with a strength grade of P·O42.5; The medium sand is machine-made sand with a bulk density of 1517 kg / m 3 ; The crushed stone is 5-25mm continuous gradation, and the bulk density is 1552kg / m 3 ; The fly ash is Class II Class C fly ash; The water reducer is a polycarboxylate water reducer, model number is PC-1007.

3. The crack-resistant concrete according to claim 1, characterized in that: In the method for preparing the surface fluoride-modified basalt fiber, the immersion time is 110-130 minutes; The concentration of the hydrochloric acid solution is 0.45-0.55 mol / L; The heating temperature to completely dissolve the polyvinylidene fluoride is 70° C. The time of heat preservation and stirring is 5.5-6.5h; The temperature of the evaporating solvent is 165°C; The calcination method is to control the temperature to be 575-625° C. for calcination, and the calcination time is 85-100 minutes.

4. The crack-resistant concrete according to claim 1, characterized in that: In the method for preparing the surface fluoride-modified basalt fiber, the mass ratio of the basalt fiber to the hydrochloric acid solution is 1:6.5-7.5; The basalt fiber has a diameter of 7-9 μm, a length of 7.0-8.0 mm, a silicon dioxide content of 54.2%, and an aluminum oxide content of 13.5%; The mass ratio of the polyvinylidene fluoride, dimethylacetamide and surface activated basalt fiber is 9-11:100-150:40-50; The molecular weight of the polyvinylidene fluoride is 1.1-1.5×10 5 g / mol.

5. The crack-resistant concrete according to claim 1, characterized in that: In the method for preparing the ion exchange silica fume, the silica fume and the saturated aluminum chloride solution are mixed and stirred for 25-35 minutes; The standing time is 3.5-4.5h; The calcination method is to carry out calcination at 710-730° C. for 80-100 minutes.

6. The crack-resistant concrete according to claim 1, characterized in that: In the preparation method of the ion exchange silica fume, the mass ratio of silica fume to saturated aluminum chloride solution is 1:14-16; The particle size of the silica fume is 0.11 μm, the silicon dioxide content is 85.2%, and the specific surface area is 27355 m 2 / kg.

7. The method for preparing crack-resistant concrete according to claim 1, characterized in that: The preparation method comprises the following steps: mixing raw material components of a specified mass uniformly and performing standard curing to obtain a crack-resistant concrete.

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