Impermeable and anti-cracking concrete mix proportion design method

Abstract

The invention discloses an impervious and anti-cracking concrete mix proportion design method which comprises the following steps: determining theoretical water consumption according to slump and material parameters required by concrete, and further determining actual water consumption according to the water reducing rate of a water reducing agent; determining a water-binder ratio value range according to performance parameter requirements of concrete and a mineral admixture dosage range, and determining the dosage of a binding material according to actual water consumption; according to the performance parameters of each component in the concrete and the obtained water-binder ratio, determining the value range of the sand ratio required by the concrete reaching the expected strength grade, anti-permeability grade and anti-crack grade, and further determining the dosage of each component in the aggregate; a mixture is prepared by selecting an optimal mixing ratio from a plurality of groups of water-binder ratios, sand ratios and mixing ratios of mineral admixture parameters, and the requirements of C40 strength grade, P12 impermeability grade and crack resistance of concrete are met by adjusting the slurry-aggregate ratio and the fiber mixing amount of the mixture.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete preparation, and specifically to a method for designing the mix proportion of impermeable and crack-resistant concrete. Background Art

[0002] A deep diving pool is a diving entertainment facility with a relatively large depth. Different from traditional square or circular diving pools, a super-deep special-shaped diving pool adopts a more complex structural design to meet specific usage requirements or environmental conditions.

[0003] Since a deep diving pool is cast with mass concrete, and mass concrete often has problems with cracks, these cracks will seriously damage the strength, durability and overall stability of the structure. In addition, after being filled with water, it will form a relatively large pressure on the concrete of the pool wall and the pool bottom, which requires that the concrete not only meets the construction workability and mechanical properties, but also has good impermeability and crack resistance.

[0004] In terms of structural form, a deep diving pool usually adopts a concrete structure to ensure sufficient strength and stability, and at the same time, waterproof performance and crack resistance should also be considered. There is less research on the comprehensive analysis of the work performance, mechanical properties and durability of the concrete structure adopted by the deep diving pool and the optimization of its mix proportion in the existing concrete mix proportion design methods, resulting in the difficulty of the prepared concrete performance to meet the requirements of the bearing capacity and compressive capacity of the deep diving pool, especially in the deep water environment, it is difficult to cope with the challenges of water pressure and geological conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for designing the mix proportion of impermeable and crack-resistant concrete, and to determine the mix proportion of C40P12 mass concrete with better waterproof performance, higher crack resistance level and compliance with strength, so as to improve the durability and safety of the concrete structure of related projects.

[0006] The technical solution of the present invention is as follows: A method for designing the mix proportion of impermeable and crack-resistant concrete, comprising the following steps: S1 Determine the theoretical water consumption according to the required slump of the concrete and the material parameters, and then determine the actual water consumption according to the water reduction rate of the water reducing agent.

[0007] S2 Determine the range of water-binder ratio according to the performance parameter requirements of the concrete and the range of mineral admixture dosage, and determine the dosage of the binder and the dosage of each component therein according to the determined actual water consumption.

[0008] S3 Determine the range of sand ratio required for the concrete to reach the expected strength grade, impermeability grade and crack resistance grade according to the performance parameters of each component of the binder in the concrete and the obtained range of water-binder ratio, and then determine the dosage of each component in the aggregate.

[0009] S4 selects multiple water-binder ratio values, multiple sand ratios, and multiple mineral admixture dosages from the determined ranges of water-binder ratio, sand ratio, and mineral admixture dosage for configuration, designs multiple mix ratios with different water-binder ratios, sand ratios, and mineral admixture dosages, and selects the best one from the multiple mix ratios of water-binder ratio, sand ratio, and mineral admixture dosage to prepare the mixture.

[0010] S5 adjusts the paste-aggregate ratio and fiber dosage of the mixture prepared in S4 to make the mixture meet the requirements of concrete for workability, compressive strength, and impermeability and crack resistance performance.

[0011] In order to meet the requirements of concrete workability and strength and make the crack resistance of concrete meet the requirements of pumped concrete in engineering. When adjusting the paste-aggregate ratio and adding fibers, although the crack situation of concrete can be improved, it has an impact on workability and strength. Therefore, a suitable fiber dosage and the increased value of the paste-aggregate ratio need to be found to meet the requirements of various properties of C40P12 impermeable and crack-resistant concrete in engineering.

[0012] Further, the cementitious materials include: cement, fly ash, and ground granulated blast-furnace slag; the aggregates include: manufactured sand and coarse aggregates, and the coarse aggregates include crushed stones with different particle sizes. The mineral admixture dosage is the mass ratio of the fly ash and the ground granulated blast-furnace slag to the cementitious materials.

[0013] Further, the material parameters in S1 include: the material parameters of the cementitious materials, including: the cement parameters, using P.O42.5 cement; the fly ash parameters, using Class II fly ash; the ground granulated blast-furnace slag parameters, using S95 grade ground granulated blast-furnace slag, and the mass ratio of fly ash to ground granulated blast-furnace slag is 2:3; the material parameters of the aggregates, including: the manufactured sand parameters, belonging to medium sand according to the fineness modulus (2.8) and particle size; the coarse aggregates, including: crushed stones with a particle size of 5mm - 16mm and crushed stones with a particle size of 16mm - 25mm, and the mass ratio of crushed stones with a particle size of 5mm - 16mm to crushed stones with a particle size of 16mm - 25mm is 3:7; the water-reducing agent parameters and the expansive agent parameters, using a high-efficiency pumping agent as the water-reducing agent with a water reduction rate of 22%; using a HEA type expansive agent as the expansive agent, and the main component is CaCO3.

[0014] Further, the concrete performance parameter requirements in S2 include: concrete strength grade, cement surplus coefficient, fly ash influence coefficient, ground granulated blast-furnace slag influence coefficient, crushed stone regression coefficient, and standard deviation.

[0015] Further, according to the designed strength f of the concrete cuo 、the cement strength grade f ceg 、the cement surplus coefficient γ c 、the fly ash influence coefficient γf 、Mineral powder influence coefficient γ s 、Gravel regression coefficient a a and a b The method for determining the water - binder ratio W / B is as follows: Calculate the 28 - day mortar compressive strength f of cement ce =γ c f ceg .

[0016] Calculate the 28 - day mortar compressive strength f of the binder b =γ f γ s f ce .

[0017] Calculate the water - binder ratio W / B = (a a* f b ) / (f cuo +a a a b f b ).

[0018] Considering the changes in the content of mineral admixtures, the durability of concrete, the principle of the maximum water - binder ratio, and the characteristics of raw materials, the reference water - binder ratio is selected: 0.35 - 0.40. The designed value range of the content of mineral admixtures is 25% - 35%. It can meet the requirements of various working performances and strength of C40P12 impermeable and crack - resistant concrete in engineering. C40P12 concrete refers to concrete with a strength grade of C40 and an impermeability grade of P12.

[0019] Furthermore, according to the water - binder ratio and slump, the designed value range of the sand ratio of medium sand in S3 is 35% - 40%.

[0020] Furthermore, the actual water consumption per cubic meter of concrete is determined according to the formula m wo =m wk (1 - w R ), where w R is the water - reducing rate of the water - reducing agent, and m wk is the theoretical water consumption.

[0021] Furthermore, the designed values of different water - binder ratios in S4 are 0.36, 0.38, and 0.4 respectively; the designed values of different sand ratios are 35%, 38%, and 40% respectively; the designed values of different contents of mineral admixtures are 25%, 30%, and 35% respectively.

[0022] Furthermore, first test the work performance and compressive strength grade of the mixture prepared with the selected mix ratio. Under the condition of meeting the work performance, then adjust the paste - aggregate ratio and fiber content in S5.

[0023] Compared with the prior art, the beneficial effects of the present invention are: Through exploring the workability of concrete under different mix ratios, as well as the development trends of compressive strength, impermeability and crack resistance, and optimizing the design according to the test results, the mix ratio of C40P12 mass concrete with good waterproof performance, high crack resistance grade and compliance with strength requirements is determined. Through the mix ratio design method of the present invention, it can be ensured that the strength of the concrete reaches the design requirements, and it has good durability and can be used stably for a long time. At the same time, a reasonable mix ratio design can make the strength of the concrete meet the requirements while reducing the usage amount of raw materials as much as possible, so as to achieve the purpose of reducing production costs. By correctly selecting the proportions of each component in the mix ratio and parameters such as the water-binder ratio, the concrete has good crack resistance and durability, so as to achieve better use effects. In addition, by exploring the workability of concrete under different mix ratios, as well as the development trends of compressive strength, impermeability and crack resistance, and optimizing the design according to the test results, the mix ratio of mass concrete with good waterproof performance, high crack resistance grade and compliance with the strength of C40 is determined, improving the durability and safety of related projects. Specific embodiments

[0024] The specific embodiments of the present invention will be described in detail below.

[0025] Embodiment The requirements for the mix ratio design of underwater impermeable and crack-resistant mass concrete are to meet the workability, mechanical properties, crack resistance and impermeability of the concrete in the underwater special-shaped diving pool environment. The workability of the concrete refers to various physical, chemical and mechanical properties of the concrete during the construction process, such as workability, setting time, ductility and durability, etc.

[0026] In this embodiment, the slump requirement for pumped concrete is 180mm±20mm, the slump loss in 1h is ±30mm, the compressive strength grade is C40, the impermeability grade is P12, and problems such as surface cracks of the concrete caused by the large lateral pressure of groundwater on the pool wall need to be overcome. An impermeable and crack-resistant concrete mix ratio design method includes the following steps: S1 Determine the theoretical water consumption according to the required slump of the concrete and material parameters, and then determine the actual water consumption according to the water reduction rate of the water reducer; the actual water consumption per cubic meter of concrete is determined according to the formula m wo =m wk (1-w R ), where w R is the water reduction rate of the water reducer, m wk is the theoretical water consumption, and the theoretical water consumption is determined according to the slump by referring to relevant specifications.

[0027] The material parameters include: Cement parameters: P.O42.5 cement is used; Fly ash parameters: Class II fly ash is used. P.O is the code for ordinary Portland cement, where "P" represents cement and "O" represents ordinary, and 42.5 indicates the strength grade of the cement.

[0028] Mineral powder parameters: S95 grade mineral powder is used, and the mass ratio of fly ash to mineral powder is 2:3. S95 grade mineral powder refers to granulated blast furnace slag powder that complies with the national standard GB / T18046 - 2000, and its activity index is greater than or equal to 95% at 28 days.

[0029] Mechanism sand parameters: According to the fineness modulus (2.8) and particle size, it belongs to medium sand.

[0030] Coarse aggregate, including: crushed stone with a particle size of 5mm - 16mm and crushed stone with a particle size of 16mm - 25mm, and the mass ratio of crushed stone with a particle size of 5mm - 16mm to crushed stone with a particle size of 16mm - 25mm is 3:7.

[0031] Water reducing agent: High - efficiency pumping agent is used, and the water reducing rate (W R ) is 22%.

[0032] Expansion agent: HEA type expansion agent is used, and the main component is CaCO3.

[0033] Performance parameters include the slump, strength grade, cement surplus coefficient, fly ash influence coefficient, mineral powder influence coefficient, crushed stone regression coefficient, and standard deviation required for the concrete. The slump requirement for pumped concrete is 180mm, and the maximum aggregate size of the concrete is 25mm. According to the slump required in the project, the slump specification is consulted to determine the theoretical water consumption at this time as 210kg / m 3 - 235kg / m 3 , and then through the water reducing rate (W R ) of the water reducing agent and the formula m wo = m wk (1 - w R ), the actual water consumption per cubic meter of concrete is determined to be 163.8kg / m 3 - 183.3kg / m 3 .

[0034] S2 determines the range of water - binder ratio according to the performance parameter requirements of the concrete and the range of mineral admixture dosage, and determines the dosage of the binder and the dosage of each component therein according to the determined actual water consumption. The mineral admixture dosage is the mass ratio of the fly ash and the mineral powder to the binder. Specifically, the performance parameter requirements of the concrete are: the designed strength f cuo of the concrete, the strength grade f ceg of the cement, the cement surplus coefficient γ c of the cement, the fly ash influence coefficient γf 、Mineral powder influence coefficient γ s 、Regression coefficient a of crushed stone a and a b , the water-binder ratio W / B is determined through the performance parameter requirements of concrete and the dosage range of mineral admixtures; where f ce = γ c f ceg , f b = γ f γ s f ce , W / B = (a a* f b ) / (f cuo + a a a b f b ).

[0035] ① Calculate the 28-day mortar compressive strength of cement.

[0036] The cement used is Hongshi P.O 42.5 cement, and the cement strength grade f ceg = 42.5 MPa, the cement surplus coefficient γ c = 1.16, and the obtained 28-day mortar compressive strength of cement f ce = γ c f ceg = 1.16 × 42.5 = 49.3 MPa.

[0037] ② Calculate the 28-day mortar compressive strength of the binder.

[0038] Given that the 28-day mortar compressive strength of cement f ce = 49.3 MPa, the minimum dosage of mineral admixture is 25%, and the influence coefficient γ f of fly ash is taken as 0.8, and the influence coefficient γ s of mineral powder is taken as 1.00, and the obtained 28-day mortar compressive strength of the binder f b = γ f γ s f ce = 0.8 × 1 × 49.3 = 39.4 MPa.

[0039] ③ Calculate the water-binder ratio of concrete.

[0040] Given that the predetermined strength f cuo of concrete = 48.2 MPa, the 28-day mortar compressive strength of the binder f b = 39.4 MPa, and it is mixed with crushed stone, a a = 0.53, a b = 0.20, calculate the water-binder ratio: W / B = (a a fb ) / (f cuo +a a a b f b ) = 0.53×39.4 / (48.2 + 0.53×0.20×39.4) = 0.40。

[0041] Consider the mineral admixture content variation, concrete durability, maximum water-binder ratio principle, and raw material characteristics to select the reference water-binder ratio: 0.35 - 0.40.

[0042] S3 Determine the range of sand ratio required for concrete to meet the expected strength grade, impermeability grade, and crack resistance grade based on the performance parameters of each component of the binder in the concrete and the obtained water-binder ratio range, and then determine the dosage of each component in the aggregate.

[0043] S4 Select multiple water-binder ratio values, multiple sand ratio values, and multiple mineral admixture content values within the determined water-binder ratio range, sand ratio range, and mineral admixture content range for configuration, design multiple mix ratios with different water-binder ratios, sand ratios, and mineral admixture contents, and select the best mix ratio from the multiple mix ratios of water-binder ratio, sand ratio, and mineral admixture content to prepare the mixture; it can meet the requirements of pumped concrete for slump, compressive strength, impermeability grade, and crack resistance grade.

[0044] Meet the requirements of pumped concrete for slump, compressive strength, impermeability grade, and crack resistance grade by adjusting the water-binder ratio, sand ratio, and mineral admixture content. The three water-binder ratio values are 0.36, 0.38, and 0.4 respectively; the three sand ratio values are 35%, 38%, and 40% respectively; the three mineral admixture content values are 25%, 30%, and 35% respectively.

[0045] S5 Adjust the paste-aggregate ratio and fiber content of the mixture prepared in S4 to make the mixture meet the requirements of concrete for workability, compressive performance, and impermeability and crack resistance performance. The added fiber can be polypropylene fiber. In order to meet the requirements of concrete workability and strength and make the crack resistance of the concrete meet the requirements of pumped concrete in engineering. When adjusting the paste-aggregate ratio and adding fiber, although it can improve the crack situation of the concrete, it has an impact on workability and strength. Therefore, it is necessary to find a suitable fiber content and the increased value of the paste-aggregate ratio to meet the requirements of various properties of C40P12 impermeable and crack-resistant concrete in engineering. After adjustment, the workability of the C40P12 impermeable and crack-resistant concrete mixture is good, without bleeding and segregation, the paste carries the aggregate to flow, the slump at the time of discharge is 180mm ± 20mm, and the slump after 1h is 150mm - 180mm, and all performance indicators meet the design and construction requirements.

[0046] It should be noted that the test process is divided into two major parts, namely the basic mix proportion design and the optimized mix proportion design. The water-binder ratio, sand ratio, and mineral admixture are three variables in the basic mix proportion design. Through 27 groups of tests with 3×3×3, the two mix proportions with the best workability and compressive strength grade are obtained.

[0047] The optimized mix proportion is to design 8 groups of mix proportion tests with 2×2×2 by adjusting the paste-aggregate ratio and fiber dosage on the premise of 2 groups of basic mix proportions.

[0048] Application Example 1: According to a method for designing the mix proportion of impermeable and crack-resistant concrete, the required slump of the pumped concrete in this project is 180mm±20mm, and the maximum particle size of the crushed stone is 25mm. The theoretical water consumption is determined to be 220kg / m 3 , and the actual water consumption is determined to be 172.28kg / m 3 .

[0049] The designed value range of the mineral admixture content is 25%-35%, and the designed value range of the water-binder ratio is 0.35-0.4.

[0050] According to the maximum particle size of the crushed stone being 25mm and the range of the water-binder ratio, the designed value range of the sand ratio is 35%-40%; the theoretical concrete dosage is 2350kg / m 3 -2450kg / m 3 .

[0051] Among the 27 groups of mix proportions, a group of basic mix proportion with a water-binder ratio of 0.38, a mineral admixture content of 25%, and a sand ratio of 40% is selected, which consists of the following materials: 172.28kg of water per cubic meter of concrete; 340.04kg of cement; 45.34kg of fly ash; 68.01kg of slag powder; 8.61kg of water reducer; 709.73kg of manufactured sand; 1064.60kg of coarse aggregate; 36.27kg of expansion agent.

[0052] S5 meets the requirements of the concrete for workability, compressive performance, and impermeability and crack resistance by increasing the paste-aggregate ratio by 2% and adding 0.9kg / m³ of fiber dosage on the basis of the basic mix proportion. The final mix proportion obtained consists of the following materials: 179.33kg of water per cubic meter of concrete; 354.33kg of cement; 47.33kg of fly ash; 71.00kg of slag powder; 11.81kg of water reducer; 698.00kg of manufactured sand; 1048.00kg of coarse aggregate; 38.67kg of expansion agent; 0.9kg of fiber.

[0053] Application Example 2: According to a design method for the mix proportion of impermeable and crack - resistant concrete, the required slump of the pumped concrete in this project is 180mm ± 20mm, the maximum size of the crushed stone is 25mm, and the theoretical water consumption is determined to be 232.50kg / m 3 , and according to the water - reducing rate of the water - reducing agent, the actual water consumption is determined to be 181.35kg / m 3 .

[0054] The designed value range of the mineral admixture content is 25% - 35%, and the designed value range of the water - binder ratio is 0.35 - 0.4.

[0055] According to the maximum size of the crushed stone being 25mm and the range of the water - binder ratio, the designed value range of the sand ratio is 35% - 40%; the theoretical concrete dosage is 2350kg / m 3 - 2450kg / m 3 .

[0056] Among 27 groups of mix proportions, a basic mix proportion with a water - binder ratio of 0.40, a mineral admixture content of 25%, and a sand ratio of 38% is selected, which consists of the following materials: water consumption per cubic meter of concrete is 181.35kg; cement dosage is 340.04kg; fly ash dosage is 45.34kg; slag powder dosage is 68.01kg; water - reducing agent dosage is 8.16kg; manufactured sand dosage is 670.80kg; coarse aggregate dosage is 1094.47kg; expansive agent dosage is 36.27kg.

[0057] By increasing the paste - aggregate ratio by 2% and adding a fiber content of 0.9kg / m³ on the basis of the basic mix proportion to meet the requirements of the concrete for workability, compressive performance, and impermeability and crack - resistance performance, the final mix proportion obtained consists of the following materials: water consumption per cubic meter of concrete is 190.33kg; cement dosage is 356.87kg; fly ash dosage is 47.58kg; slag powder dosage is 71.37kg; water - reducing agent dosage is 11.90kg; manufactured sand dosage is 666.16kg; coarse aggregate dosage is 1086.89kg; expansive agent dosage is 38.07kg; fiber dosage is 0.9kg.

[0058] The performance of a C40P12 impermeable and crack - resistant concrete prepared in Application Example 1 and Application Example 2 is tested, and the results are as follows:

[0059] The following conclusions are drawn from the performance test results of a C40P12 impermeable and crack - resistant concrete prepared in Application Example 1 and Application Example 2: (1) Polypropylene fibers will cause a decrease in the fluidity of concrete. When other factors remain unchanged, with the increase in fiber content, the inhibitory effect of polypropylene fibers on the fluidity of concrete gradually strengthens. However, increasing the paste-aggregate ratio can improve the fluidity loss of concrete caused by adding fibers. With the increase in the paste-aggregate ratio, the fluidity of concrete increases within a certain range.

[0060] (2) After adding fibers, the early compressive strength of concrete is slightly increased, but with the gradual increase in the content of polypropylene fibers, its enhancing effect on the compressive capacity of concrete gradually decreases. At the same time, although increasing the paste-aggregate ratio will slightly decrease the compressive strength of concrete, when the water-binder ratio is small, appropriately increasing the paste-aggregate ratio after adding fibers can still ensure the strength of concrete. The impermeability grade of C40 concrete can all reach P12.

[0061] (3) With the increase in fiber dosage, the number and area of cracks when concrete cracks show a decreasing trend, the higher the crack resistance grade of the obtained concrete, and the stronger the ability of concrete to resist early restrained deformation. At the same time, increasing the paste-aggregate ratio will have an adverse effect on the crack resistance performance of concrete. Therefore, considering the two factors comprehensively, it is concluded that when the water-binder ratio is 0.4, the sand ratio is 38% and the water-binder ratio is 0.38, the sand ratio is 40%, controlling the mineral admixture at 25%. At this time, adding 0.9 kg / m³ of polypropylene fibers and increasing the paste-aggregate ratio by 2%, the two groups of mix-ratio concretes obtained have good workability, the compressive strength is greater than 45 Mpa, the impermeability grade is P39, and the crack resistance grade is grade II, which can meet the requirements of engineering construction and the crack resistance performance at the same time.

[0062] The above discloses only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A design method for the mix proportion of impermeable and crack-resistant concrete, characterized in that It includes the following steps: Determine the theoretical water consumption according to the required slump of the concrete and the material parameters, and then determine the actual water consumption according to the water reduction rate of the water reducing agent; Determine the range of water-binder ratio according to the performance parameter requirements of the concrete and the range of mineral admixture content, and determine the dosage of the binder and the dosage of each component therein according to the determined actual water consumption; Determine the range of sand ratio required for the concrete to meet the expected strength grade, impermeability grade and crack resistance grade according to the performance parameters of each component of the binder in the concrete and the obtained range of water-binder ratio, and determine the dosage of each component in the aggregate according to the range of sand ratio; Select multiple water-binder ratio values, multiple sand ratio values and multiple mineral admixture content values within the determined range of water-binder ratio, range of sand ratio and range of mineral admixture content for configuration, design multiple mix ratios with different water-binder ratios, sand ratios and mineral admixture contents, and select the best mix ratio from the multiple mix ratios of water-binder ratio, sand ratio and mineral admixture content to prepare the mixture; Adjust the paste-aggregate ratio and fiber content of the prepared mixture to make the mixture meet the requirements of the concrete for workability, compressive performance, impermeability and crack resistance performance.

2. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 1, characterized in that, The binder includes: cement, fly ash and slag powder; the aggregate includes: manufactured sand and coarse aggregate, and the coarse aggregate includes gravels with different particle sizes; the content of the mineral admixture is the mass ratio of the fly ash and the slag powder to the binder.

3. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 2, characterized in that, The material parameters include: The material parameters of the binder, including: cement parameters, using P.O42.5 cement; fly ash parameters, using Class II fly ash; slag powder parameters, using S95 grade slag powder, and the mass ratio of fly ash and slag powder is 2:3; The material parameters of the aggregate, including: manufactured sand parameters, using medium sand; the coarse aggregate includes: gravels with a particle size of 5mm - 16mm and gravels with a particle size of 16mm - 25mm, and the mass ratio of the gravels with a particle size of 5mm - 16mm and the gravels with a particle size of 16mm - 25mm is 3:7; Water reducing agent parameters and expansion agent parameters, the water reducing agent uses a high-efficiency pumping agent with a water reduction rate of 22%; the expansion agent uses a HEA type expansion agent.

4. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 1, characterized in that, The performance parameter requirements of the concrete include: concrete strength grade, cement surplus coefficient, fly ash influence coefficient, slag powder influence coefficient, gravel regression coefficient and standard deviation.

5. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 4, characterized in that, According to the design strength f of concrete cuo , the strength grade f of cement ceg , the surplus coefficient γ of cement c , the influence coefficient γ of fly ash f , the influence coefficient γ of slag powder s , the regression coefficient a of crushed stone a and a b The method for determining the water-binder ratio W / B is as follows: Calculate the compressive strength f of cement mortar ce =γ c f ceg ; Calculate the compressive strength f of the cementitious material mortar b =γ f γ s f ce ; Calculate the water-cement ratio W / B = (a a* f b ) / (f cuo + a a a b f b ); Select the reference water-binder ratio: 0.35 - 0.40; The designed value range of the mineral admixture content is 25% - 35%.

6. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 1, characterized in that, The actual water consumption per cubic meter of concrete is determined according to the formula m wo =m wk (1 - w R ), where w R is the water reduction rate of the water reducing agent, and m wk is the theoretical water consumption.

7. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 1, characterized in that, The selected different designed values of the water-binder ratio are 0.36, 0.38 and 0.4 respectively; the selected different designed values of the sand ratio are 35%, 38% and 40% respectively; the selected different designed values of the mineral admixture content are 25%, 30% and 35% respectively.

8. A method for designing the mix proportion of impermeable and crack-resistant concrete according to claim 1, characterized in that, First, test the workability and compressive grade of the mixture prepared according to the selected mix ratio, and then adjust the paste-aggregate ratio and fiber content of the prepared mixture.

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