Concrete mix proportion design method based on machine-made sandstone powder as cementing material

Abstract

The invention relates to a concrete mix proportion design method based on machine-made sandstone powder, and relates to the technical field of concrete preparation, and the method comprises the following steps: according to a selected cementing material and the content of stone powder screened from machine-made sand, calculating to obtain a stone powder excess value; acquiring a mix proportion parameter of the reference concrete and the strength of the reference concrete; the excess stone powder in the machine-made sand is used as an inert mineral admixture, and the amount of cement replaced by the stone powder is calculated according to the substitution coefficient gamma c and the excess value of the stone powder; and testing the water demand ratio of the stone powder, and calculating to obtain the final water consumption of the concrete. The resource comprehensive utilization rate of the high-stone-powder-content dry-process machine-made sand can be increased, and the cement consumption is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of concrete preparation, and in particular to a concrete mix design method based on machine-made sand and gravel powder as a cementitious material. Background Art

[0002] The field of concrete mixing technology has made significant progress in recent years. Modern concrete has become an important material in the construction industry with its low water-cement ratio, high compressive strength and good fluidity. With the popularization of green and low-carbon concepts, the output of traditional mineral admixtures such as fly ash and slag has gradually decreased, making it difficult to meet the needs of large-scale infrastructure. In this context, machine-made sand has received widespread attention as an alternative resource, and the stone powder produced in the production process has potential utilization value.

[0003] To solve the problem of natural sand resource shortage, the industry usually adopts the following methods: First, waste stone chips are used to partially replace natural sand or machine-made sand, but this method has a low resource utilization rate; second, machine-made sand is made to meet national standards through water washing, but this process is prone to environmental pollution and leads to the loss of stone powder. In addition, there are studies that try to directly use stone powder as an admixture, but there is a lack of systematic design methods.

[0004] In the prior art, although various methods have been tried to utilize the stone powder in machine-made sand, there are still deficiencies in the application specifications and mix design of machine-made sand with high stone powder content. In particular, the problem of how to scientifically and rationally utilize excess stone powder as a cementitious material while ensuring the performance of concrete needs to be solved urgently. Summary of the invention

[0005] The present application provides a concrete mix design method based on machine-made sand and stone powder as a cementitious material, which can improve the comprehensive resource utilization rate of dry-process machine-made sand with high stone powder content and reduce cement consumption.

[0006] The present application provides a concrete mix design method based on machine-made sand and gravel powder as a cementitious material, which adopts the following technical solution: A concrete mix design method based on machine-made sand and gravel powder as a cementitious material, comprising: According to the selected cementitious material and the stone powder content screened out from the machine-made sand, the stone powder excess value is calculated; Obtaining the mix ratio parameters and benchmark concrete strength of the reference concrete; The excess stone powder in the machine-made sand is used as an inert mineral admixture and is added according to the substitution coefficient γ c Calculate the amount of cement replaced by stone powder by comparing with the excess value of stone powder; Test the water demand ratio of stone powder and calculate the final water consumption of concrete.

[0007] By adopting the above technical solution, after obtaining the available amount of stone powder from the current manufactured sand, the mix ratio parameters and strength of the reference concrete are obtained to provide a basis for adjusting the mix ratio of the concrete; the excess stone powder is used as an inert mineral admixture and the amount of cement replaced is calculated to improve the comprehensive utilization rate of resources, reduce the amount of cement used, and lower the production cost; the water demand ratio of the stone powder is tested to adjust the water consumption so that the workability and strength of the concrete meet the requirements.

[0008] In a preferred example of the present application, it can be further configured that: the step of calculating and obtaining the excess value of stone powder according to the selected cementitious material and the content of stone powder screened out from the manufactured sand includes: Determine the content of stone powder in the manufactured sand through a 45μm negative pressure screening test; According to the content of stone powder in the manufactured sand and the limit value of stone powder content, calculate the excess value of stone powder in the manufactured sand and adjust the composition of the cementitious material part in the manufactured sand concrete.

[0009] By adopting the above technical solution, the content of stone powder in the manufactured sand can be accurately determined, and the excess value of stone powder can be calculated based on the limit value of stone powder content, thereby providing a quantitative basis for subsequent adjustment of the composition of the cementitious material in the concrete, improving the utilization rate of stone powder resources, reducing the amount of cement used, and ensuring the stable performance of the concrete at the same time.

[0010] In a preferred example of the present application, it can be further configured that: before the step of calculating the excess value of stone powder in the manufactured sand according to the content of stone powder in the manufactured sand and the limit value of stone powder content and adjusting the composition of the cementitious material part in the manufactured sand concrete, it includes: Set the MB value of the manufactured sand ≤ 1.0, and the limit value of the stone powder content in the manufactured sand is between 0 and 20%.

[0011] By adopting the above technical solution, setting the MB value and the limit value of stone powder content can reduce the situation that it is difficult to design and produce the mix ratio of manufactured sand concrete according to the stone powder content due to the high content of stone powder, and make the overall performance of the concrete tend to be stable.

[0012] In a preferred example of the present application, it can be further configured that: the step of obtaining the mix ratio parameters and the strength of the reference concrete includes: Use the absolute volume method to calculate and obtain the amounts of sand, gravel and cementitious material of the reference concrete, and calculate the strength and water-cement ratio of the configured reference concrete, where the mix ratio parameters include the amount of cement, the amount of active mineral admixture, the amount of fine aggregate, the amount of coarse aggregate, and the amount of water.

[0013] By adopting the above technical solution, based on the absolute volume rather than the weight of each material, the density differences of different materials can be considered, thereby ensuring the accuracy of the concrete mix ratio, providing accurate basic data for the subsequent replacement of cement dosage with stone powder, and clarifying the dosage of each component in the mix ratio parameters, which helps to optimize resource utilization and reduce errors.

[0014] In a preferred example of the present application, it can be further configured as follows: The steps of calculating the sand and gravel dosage and the cementitious material dosage of the reference concrete by using the absolute volume method, and calculating the strength and water-cement ratio of the configured reference concrete, where the mix ratio parameters include the cement dosage, the dosage of active mineral admixtures, the fine aggregate dosage, the coarse aggregate dosage, and the water dosage, include: Calculating and obtaining the strength f of the reference concrete b , through the formula: f b =γ f ·γ s ·γ c ·f ce , where, γ f is the activity coefficient of fly ash, γ s is the activity coefficient of slag powder, and f ce is the strength grade of cement.

[0015] By adopting the above technical solution, comprehensively considering the influence of various factors on the concrete strength, the accuracy of strength prediction is improved, and further the scientificity and rationality of concrete mix ratio design are improved.

[0016] In a preferred example of the present application, it can be further configured as follows: Using the excess stone powder in the manufactured sand as an inert mineral admixture, and calculating the part of the stone powder replacing the cement dosage according to the replacement coefficient r c and the stone powder excess value, including: Obtaining the replacement coefficient of the stone powder, and the replacement coefficient γ of the stone powder c is obtained by linear interpolation according to the stone powder content and the concrete strength grade.

[0017] By adopting the above technical solution, the replacement coefficient of the stone powder can be determined by linear interpolation according to the stone powder content and the concrete strength grade, so as to accurately control the proportion of the stone powder replacing the cement dosage. This not only improves the utilization rate of the stone powder in the manufactured sand, but also can effectively reduce the cement dosage on the premise of ensuring the concrete performance, reduce the production cost and carbon emissions. The application of the linear interpolation method makes the value of the replacement coefficient more standardized and reasonable, meeting different engineering requirements.

[0018] In a preferred example of the present application, it can be further configured as follows: Using the excess stone powder in the manufactured sand as an inert mineral admixture, and according to the replacement coefficient γc Steps for calculating the amount of cement replaced by stone powder based on the excess value of stone powder, including: Set the required concrete strength as f and determine whether f b ≥ f; If not satisfied, according to the replacement coefficient γ of the stone powder c Obtain the mass m of cement replaced by stone powder c , through the formula: m c = m c0 - (γ c - 1)m s0 Δδ, where, m c0 is the original cement dosage, m s0 is the original fine aggregate dosage, Δδ is the excess value of stone powder, and the constraint condition is m c ≤ 0.2·m c0 , and the dosage m of active mineral admixture after replacing cement with stone powder f = m f0 , the coarse aggregate dosage m g = m g0 .

[0019] By adopting the above technical solution, setting the required concrete strength and determining whether the strength condition is satisfied, the mechanical properties of the final concrete meet the design requirements, minimizing the problem of insufficient strength caused by replacing cement with stone powder, and realizing the partial replacement effect of stone powder as an inert mineral admixture, effectively reducing the cement dosage, lowering the production cost and improving the resource utilization rate. Setting the constraint condition for the replaced cement quality limits the maximum ratio of stone powder replacing cement, preventing negative impacts on concrete performance caused by excessive replacement, and at the same time ensuring that the dosages of active mineral admixture and coarse aggregate remain unchanged, maintaining the stability of the overall concrete mix ratio.

[0020] In a preferred example of the present application, it can be further configured as: the steps for testing the water demand ratio of stone powder and calculating the final water consumption of concrete, including: Calculate and obtain the final water consumption m of concrete wa , through the formula: m wa = m wa0 - (1 - c)δ, where, m wa0 is the original water consumption, c is the water demand ratio of stone powder, and δ is the stone powder content.

[0021] By adopting the above technical solution, on the premise of ensuring the performance of concrete, the excess stone powder in the manufactured sand can be effectively utilized as part of the cementitious material, reducing the cement dosage, thereby achieving the effect of comprehensive utilization of resources and cost reduction.

[0022] In a preferred example, the present application can be further configured as follows: obtaining the substitution coefficient of stone powder, where the substitution coefficient γ of stone powder c Before the step of obtaining the value by linear interpolation according to the stone powder content and the concrete strength grade, the following steps are further included: Establish a two-dimensional interpolation table of concrete strength grade and stone powder content; According to the concrete strength grade and the stone powder content in the manufactured sand in the actual project, determine γ through bivariate linear interpolation c .

[0023] By adopting the above technical solution, establishing a two-dimensional interpolation table of concrete strength grade and stone powder content can quickly and accurately match the value range of the stone powder substitution coefficient γc according to the actual project requirements.

[0024] In summary, the present application has the following beneficial technical effects: 1. By calculating the excess value of stone powder and using it as an inert mineral admixture to replace part of the cement, the present application effectively reduces the cement consumption and lowers the production cost of concrete; 2. By using the stone powder substitution coefficient and the water demand ratio to optimize the concrete mix design, the present application improves the comprehensive resource utilization rate of manufactured sand with high stone powder content in concrete while ensuring that the concrete strength and water consumption meet the project requirements. Description of the Drawings

[0025] Figure 1 is a flowchart of a concrete mix design method based on stone powder in manufactured sand as a cementitious material in one embodiment of the present application.

[0026] Figure 2 is a sub-step flowchart of step S1 in one embodiment of the present application.

[0027] Figure 3 is a flowchart of the steps added before step S11 in one embodiment of the present application.

[0028] Figure 4 is a sub-step flowchart of step S2 in one embodiment of the present application.

[0029] Figure 5 is a sub-step flowchart of step S20 in one embodiment of the present application.

[0030] Figure 6 is a sub-step flowchart of step S3 in one embodiment of the present application Figure 1 .

[0031] Figure 7 is a sub-step flowchart of step S3 in one embodiment of the present application Figure 2 .

[0032] Figure 8 It is a sub-step flow chart of step S4 in one embodiment of the present application.

[0033] Figure 9 It is a flow chart of the steps added before step S30 in one embodiment of the present application. Detailed implementation manners

[0034] The following will Figures 1-9 make a further detailed description of the present application with reference to the appended

[0035] It should be noted that all actions of obtaining data or all actions of obtaining information or data in the present application are carried out in accordance with the corresponding data protection regulations and policies of the country where it is located and with the authorization of the corresponding users.

[0036] Refer to Figure 1 , a concrete mix design method based on manufactured sand powder as a cementitious material, specifically including: S1. Calculate and obtain the stone powder excess value according to the selected cementitious material and the stone powder content screened out from the manufactured sand.

[0037] Specifically, according to the selected cementitious material and the stone powder content (below 75μm) screened from the manufactured sand, they jointly constitute the cementitious material part in the manufactured sand concrete. Assuming the stone powder content in the manufactured sand is δ, and the stone powder content limit value δ 0 , when the concrete strength grade is C55 - C30, the stone powder content limit value δ0 is 7.0%; when the concrete strength grade ≤ C25, the stone powder content limit value δ0 is 10.0%.

[0038] S2. Obtain the mix proportion parameters of the reference concrete and the reference concrete strength.

[0039] Specifically, by obtaining the mix proportion parameters of the reference concrete, it can provide a standardized reference for the design of concrete to ensure that the performance of the concrete meets specific engineering requirements. Moreover, the determination of the reference concrete strength provides a scientific basis for the strength design of the concrete, which helps to improve the safety and reliability of the structure.

[0040] S3. Take the excess stone powder in the manufactured sand as an inert mineral admixture, and calculate and obtain the amount of stone powder replacing cement according to the replacement coefficient γ c and the stone powder excess value.

[0041] Specifically, "Technical Specification for Application of Limestone Powder in Concrete" JGJ / T 318 points out that the activity of stone powder can still reach more than 60% at 28 days. Therefore, this part of the stone powder exceeding the standard regulations can be regarded as an inert mineral admixture. By accurately calculating the replacement coefficient γ c, it is possible to achieve the optimal replacement amount of stone powder in concrete, thereby maximizing the utilization efficiency of resources while ensuring the performance of concrete.

[0042] S4. Test the water demand ratio of stone powder and calculate the final water consumption of concrete.

[0043] Specifically, precisely controlling the water consumption of concrete is crucial for preventing concrete cracking, improving the durability of concrete, and extending the service life of the structure. Therefore, by testing the water demand ratio of stone powder to adjust the water consumption, the workability and strength of concrete can be improved.

[0044] Reference Figure 2 , further, in one embodiment, step S1 is refined into the following sub-steps: S10. Determine the stone powder content in manufactured sand through a 45μm negative pressure screening test.

[0045] Specifically, during the production of dry powder manufactured sand, a large amount of stone powder is generated, and the stone powder content exceeds 10%, up to more than 20% at most. According to the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete" JGJ 52, artificial sand with a stone powder content not exceeding 10% can be used for concrete of grades C25 and below; artificial sand with a stone powder content not exceeding 7% can be used for concrete of grades C30 - C55. Then, by performing a 45μm negative pressure screening on the stone powder, the stone powder with a water-reducing effect can be screened out and combined with the cementitious material, which can further optimize the water consumption of concrete.

[0046] S11. Calculate the excess value of stone powder in manufactured sand based on the stone powder content in manufactured sand and the stone powder content limit, and adjust the composition of the cementitious material part in manufactured sand concrete.

[0047] Specifically, by precisely controlling the excess value of stone powder and dynamically optimizing the concrete mix ratio, stone powder can be more effectively used as a mineral admixture in concrete, reducing the cement consumption, lowering the cost, and at the same time improving the sustainability and environmental friendliness of concrete. In addition, this adjustment can also improve the workability and final strength of concrete, achieving the maximum utilization of resources.

[0048] In addition, reference Figure 3 , further, in one embodiment, before step S11, step S110 is added: S110. Set the MB value of manufactured sand ≤ 1.0, and the stone powder content limit in manufactured sand is between 0 and 20%.

[0049] Specifically, the control of the MB value ensures that the stone powder does not significantly increase the water demand of the concrete, thus helping to maintain the workability and strength of the concrete. At the same time, restricting the stone powder content within a reasonable range can avoid the negative impact of excessive stone powder content on the concrete performance, such as reducing strength or increasing shrinkage, which helps to improve the quality and stability of the concrete and achieve the efficient utilization of resources.

[0050] In addition, referring to Figure 4 , further, in one of the embodiments, step S2 is refined into the following sub-steps: S20. Calculate and obtain the sand and gravel dosage and the cementitious material dosage of the reference concrete by the absolute volume method, and calculate the strength and water-binder ratio of the reference concrete. The mix proportion parameters include the cement dosage, the dosage of active mineral admixtures, the fine aggregate dosage, the coarse aggregate dosage, and the water dosage.

[0051] Specifically, according to the provisions of the "Code for Design of Ordinary Concrete Mix Proportions" JGJ 55, the absolute volume method is used to obtain the sand and gravel dosage and the cementitious material dosage of the reference concrete. The absolute volume method takes into account the density differences of different materials. In concrete, the densities of cement, sand, stone powder, and water are different. The absolute volume method ensures the accuracy of the mix proportion by considering these density differences. And by measuring the volumes of the various constituent materials, the absolute volume method can more easily monitor whether the concrete mix proportion meets the design requirements, which is convenient for quality control.

[0052] Among the various parameters required for calculating the mix proportion of concrete, the active mineral admixtures mainly include fly ash, slag powder, etc. These materials can chemically react with the hydration products of cement, thereby improving the strength and durability of the concrete. Fine aggregates usually refer to natural sand, manufactured sand, stone powder, etc., which are smaller in particle size. Their function is to fill the voids in the concrete, enhance the density and crack resistance. Coarse aggregates refer to larger particles, such as crushed stone, pebbles, and broken bricks, etc., which mainly bear the load and provide volume stability.

[0053] In addition, referring to Figure 5 , further, in one of the embodiments, step S20 is refined into the following sub-steps: S200. Calculate and obtain the strength f b of the reference concrete through the formula: f b = γ f · γ s · γ c · f ce , where γ f is the activity coefficient of fly ash, γ s is the activity coefficient of slag powder, and f ce is the strength grade of cement.

[0054] Specifically, taking the manufactured sand powder concrete with a strength grade of C30 as an example, the steps to obtain the strength f of the reference concrete b include: It is known that according to the specified method in the Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete JGJ 52, it is tested and determined that the MB value of A sand ≤ 1.0, the stone powder content δ is 13.0%, the limit value of the stone powder content δ0 is 7.0%, and the excess value of the stone powder of the 1# limestone waste stone chips Δδ is calculated. Δδ = δ - δ 0 = 13.0 - 7.0% = 6.0%. The water demand ratio of the stone powder is 96%. The substitution coefficient is obtained as 1.1, the dosage of Class I fly ash is 30%, the S95 mineral powder is 30%, γ f takes 0.75, γ s takes 1.0, γ c takes the value of 1.1. Therefore, if f ce is the standard value of the 28-day compressive strength of cement, the strength f of the reference concrete b = γ f ·γ s ·γ c ·f ce = 35.0625 MPa.

[0055] In addition, referring to Figure 6 , further, in one of the embodiments, step S3 is refined into the following sub-steps: S30. Obtain the substitution coefficient of the stone powder. The substitution coefficient γ of the stone powder c is obtained by linear interpolation according to the stone powder content and the concrete strength grade.

[0056] Specifically, the substitution coefficient γ c is obtained by linear interpolation according to the stone powder content and the strength grade of the limestone waste stone chips concrete. The application of the linear interpolation method makes the value of the substitution coefficient more standardized and reasonable, adapts to different engineering requirements, thus accurately controlling the proportion of the stone powder replacing the cement dosage while improving the utilization rate of the stone powder in the manufactured sand, and can also effectively reduce the cement dosage on the premise of ensuring the concrete performance.

[0057] In addition, referring to Figure 7 , further, in one of the embodiments, step S3 is refined into the following sub-steps: S31. Set the required concrete strength as f, and judge whether it satisfies f b ≥ f.

[0058] Specifically, setting the required concrete strength and judging whether it meets the strength condition enables the mechanical properties of the final concrete to meet the design requirements, that is, the strength f of the reference concrete bWhen the concrete strength f is greater than or equal to the set requirement, it is possible to improve the accuracy of adjusting the concrete mix proportion to meet the strength requirement and reduce the problem of insufficient strength caused by replacing cement with stone powder.

[0059] S32. If not satisfied, then according to the substitution coefficient γ of the stone powder c Obtain the mass m of the stone powder replacing cement c , through the formula: m c = m c0 - (γ c - 1)m s0 Δδ, where, m c0 is the original cement dosage, m s0 is the original fine aggregate dosage, Δδ is the stone powder excess value, and the constraint condition is m c ≤ 0.2·m c0 , and the dosage m f of the active mineral admixture after replacing cement with stone powder = m f0 , the coarse aggregate dosage m g = m g0 .

[0060] Specifically, using stone powder as an inert mineral admixture can reduce the cement usage, lower costs, and at the same time improve the sustainability and environmental friendliness of concrete. Introducing the constraint condition m c ≤ 0.2·m c0 can improve the rationality of the cement dosage in concrete and avoid the negative impact on concrete performance caused by excessive replacement as much as possible. And while adjusting the cement dosage, keeping the dosage m f of the active mineral admixture and the coarse aggregate dosage m g unchanged helps to maintain the workability and volume stability of concrete.

[0061] For example, the mix proportion parameters of the C30 reference concrete determined by mix proportion calculation are as follows: the cement dosage m c0 is 180 kg, the dosages m f0 of fly ash and slag powder are 80 kg and 80 kg respectively, the fine aggregate dosage m s0 is 842 kg, and the coarse aggregate dosage m g0 is 1043 kg. Take the excess stone powder in the manufactured sand as an inert mineral admixture, calculate and determine the amount of cement replaced according to a certain substitution coefficient, and keep the bulk density unchanged, and calculate and determine the mix proportion parameters of the stone powder manufactured sand concrete. The substitution coefficient of the stone powder is taken as 1.1, and the mix proportion parameters of the C30 stone powder manufactured sand concrete determined by mix proportion calculation are as follows: Cement dosage m c = m c0 - (γ c-1) m s0 Δδ = 180 - (1.1 - 1) × 842 × 6% = 175 kg; The dosage of active mineral admixture m f = m f0 , the dosages of fly ash and slag powder are 80 kg and 80 kg respectively; The dosage of coarse aggregate m g = m g0 = 1099 kg; The dosage of fine aggregate m s = 849 kg.

[0062] Furthermore, the mix ratios, fresh properties and mechanical properties of the reference concrete and the concrete are shown in the following table respectively: Performance indexes of the concrete: In addition, referring to Figure 8 , furthermore, in one of the embodiments, step S4 is refined into the following sub-steps: S40. Calculate and obtain the final water consumption m wa of the concrete, through the formula: m wa = m wa0 - (1 - c)δ, wherein, m wa0 is the original water consumption, c is the water demand ratio of stone powder, and δ is the stone powder content.

[0063] Specifically, on the premise of ensuring the performance of the concrete, the excess stone powder in the manufactured sand is effectively utilized as part of the cementitious material, reducing the cement dosage, thereby achieving the effects of comprehensive resource utilization and cost reduction. For example, the water consumption m wa of the C30 reference concrete determined by mix ratio calculation is 160 kg, and through the formula m wa = m wa0 - (1 - c)δ = 157 kg.

[0064] In addition, referring to Figure 9 , furthermore, in one of the embodiments, before step S30, steps S300 and S301 are added: S300. Establish a two-dimensional interpolation table of concrete strength grade and stone powder content.

[0065] S301. According to the concrete strength grade and the manufactured sand stone powder content in the actual project, determine γ c through bivariate linear interpolation.

[0066] Specifically, the excess stone powder in the stone chips is used as an inert mineral admixture, and the substitution coefficient γ c is calculated according to a certain substitution coefficient, and the substitution coefficient γ c of the stone powder is calculated according to the following values according to different strength grades and substitution amounts: It should be understood that the sequence numbers of the steps in the above embodiments do not imply the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

Claims

1. A concrete mix design method based on machine-made sand and gravel powder as a cementitious material, characterized in that: include: According to the selected cementitious material and the stone powder content screened out from the machine-made sand, the stone powder excess value is calculated; Obtaining the mix ratio parameters and strength of benchmark concrete; The excess stone powder in the machine-made sand is used as an inert mineral admixture and is added according to the substitution coefficient γ c Calculate the amount of cement replaced by stone powder by comparing with the excess value of stone powder; Test the water demand ratio of stone powder and calculate the final water consumption of concrete.

2. The method according to claim 1, characterized in that: The step of calculating and obtaining the stone powder excess value according to the selected cementitious material and the stone powder content screened out from the machine-made sand comprises: The stone powder content in machine-made sand was determined by 45μm negative pressure screening test; According to the stone powder content and stone powder content limit in the machine-made sand, the excess stone powder in the machine-made sand is calculated and the composition of the cementitious material part in the machine-made sand concrete is adjusted.

3. The method according to claim 2, characterized in that Before the step of calculating the excess value of stone powder in the manufactured sand according to the stone powder content and the stone powder content limit in the manufactured sand and adjusting the composition of the cementitious material part in the manufactured sand concrete, the method comprises: Set the MB value of machine-made sand to ≤1.0, and control the stone powder content limit in the machine-made sand to between 0 and 20%.

4. The method according to claim 3, characterized in that: The step of obtaining the mix ratio parameters and the strength of the reference concrete includes: The absolute volume method is used to calculate the sand and gravel consumption and cementitious material consumption of the benchmark concrete, and the strength and water-cement ratio of the configured benchmark concrete are calculated, wherein the mix ratio parameters include cement consumption, active mineral admixture consumption, fine aggregate consumption, coarse aggregate consumption, and water consumption.

5. The method according to claim 4, characterized in that The step of using the absolute volume method to calculate the amount of sand and gravel and the amount of cementitious material of the reference concrete, and calculating the strength and water-binder ratio of the configured reference concrete, wherein the mix ratio parameters include the amount of cement, the amount of active mineral admixture, the amount of fine aggregate, the amount of coarse aggregate, and the amount of water, comprises: Calculate the strength f of the benchmark concrete b , through the formula: f b =c f ·c s ·c c ·f ce , Among them, γ f is the activity coefficient of fly ash, γ s is the activity coefficient of the mineral powder, f ce is the strength grade of cement.

6. The method according to claim 1, characterized in that The excess stone powder in the machine-made sand is used as an inert mineral admixture and is added according to the substitution coefficient r c The part of cement replaced by stone powder is calculated with the stone powder excess value, including: Obtain the substitution coefficient of the stone powder, the substitution coefficient of the stone powder γ c Linear interpolation is used to determine the value according to the stone powder content and concrete strength grade.

7. The method according to claim 5, characterized in that The excess stone powder in the machine-made sand is used as an inert mineral admixture and is added according to the substitution coefficient γ c The steps for calculating the amount of cement replaced by stone powder and the stone powder excess value include: Set the required concrete strength to f and determine whether it meets f. b ≥f; If not satisfied, then according to the substitution coefficient γ of the stone powder c Get the mass m of cement replaced by stone powder c , through the formula: m c =m c0 -(c) c -1)m s0 Dd, Among them, m c0 is the original cement consumption, m s0 is the original amount of fine aggregate, Δδ is the excess value of stone powder, and the constraint condition is m c ≤0.2·m c0 , and the amount of active mineral admixture after stone powder replaces cement m f =m f0 , coarse aggregate dosage m g =m g0 .

8. The method according to claim 7, characterized in that The step of testing the water demand ratio of stone powder and calculating the final water consumption of concrete comprises: Calculate the final water consumption of concrete m wa , through the formula: m wa =m wa0 -(1-c)δ, Among them, m wa0 is the original water consumption, c is the water demand ratio of stone powder, and δ is the stone powder content.

9. The method according to claim 6, characterized in that The stone powder substitution coefficient is obtained, and the stone powder substitution coefficient γ c Before the step of using linear interpolation to obtain values ​​according to the stone powder content and the concrete strength grade, it also includes: Establish a two-dimensional interpolation table of concrete strength grade and stone powder content; According to the concrete strength grade and the content of machine-made sand and gravel powder in the actual project, γ is determined by bivariate linear interpolation. c .

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