Machine-made sand concrete mix proportion design method

Abstract

The invention relates to the technical field of building material preparation, and provides a machine-made sand concrete mix proportion design method which comprises the following steps: calculating the accumulation void ratio of graded broken stone under the closest accumulation condition based on a compressible accumulation model; based on the stacking void ratio of the graded broken stone, the thickness of a mortar wrapping layer and the gas content of the concrete, the use amount of the graded broken stone for each cubic meter of the concrete and the mortar volume are determined; determining the water-binder ratio of the machine-made sand concrete; determining the water consumption per cubic meter of concrete based on the water reducing rate of the admixture; based on the water consumption and the water-binder ratio, determining the dosage of a cementing material, the dosage of an additive and the dosage of fly ash and slag powder; and based on the volume of the mortar, the content of the stone powder in the machine-made sand, the density of the stone powder in the machine-made sand and the apparent density of the machine-made sand, determining the dosage of cement and the machine-made sand per cubic meter of concrete. According to the invention, the aggregate in the concrete can be ensured to have a relatively small void ratio and a relatively stable stacking structure, and the volume stability and the compactness of the concrete are improved.

Description

Technical Field

[0001] This invention relates to the field of building material preparation technology, and in particular to a method for designing the mix proportion of manufactured sand concrete. Background Technology

[0002] In recent years, with the shortage of natural sand resources, the problem of supply and demand imbalance of construction sand has become increasingly prominent. In order to effectively alleviate the risks, manufactured sand has become the best alternative resource. However, many problems have also been found in the application of manufactured sand, such as poor workability of manufactured sand concrete, large shrinkage, and relatively poor resistance to chloride ion penetration.

[0003] The aforementioned problems are mainly related to the concrete mix design method. Currently, the industry uses the "Specification for Mix Design of Ordinary Concrete" (JGJ55) for mix design. However, this standard's design method is based on natural sand, while manufactured sand and natural sand have significant differences in characteristics. For example, manufactured sand contains a certain amount of stone powder. The presence of stone powder leads to a higher actual powder content and a lower actual water-cement ratio in the concrete designed according to JGJ55, which can easily cause early shrinkage cracking and is detrimental to the volume stability of the concrete. On the other hand, in traditional concrete mix design, the composition of aggregates (such as crushed stone) is generally determined empirically for different particle size ranges, which is both time-consuming and labor-intensive. Furthermore, due to the lack of theoretical guidance, the gradation composition determined by empirical methods may not necessarily guarantee that the aggregate has a small porosity and a stable aggregate structure, thus failing to maximize the skeleton and stabilizing effects of the aggregate. At the same time, the low bulk density of the aggregate results in a relatively low density of concrete and poor workability under the same amount of cementitious materials, which is detrimental to the long-term durability of concrete. Summary of the Invention

[0004] The purpose of this invention is to solve at least one technical problem in the background art and to provide a method for designing the mix proportion of manufactured sand concrete.

[0005] To achieve the above objectives, the present invention provides a method for designing the mix proportion of manufactured sand concrete, comprising: The packing void ratio of graded crushed stone under the most compact packing condition was calculated based on the compressible packing model. Based on the porosity of graded crushed stone, the thickness of the mortar coating layer, and the air content of concrete, the amount of graded crushed stone and the volume of mortar per cubic meter of concrete are determined. The water-cement ratio of manufactured sand concrete is determined based on the concrete mix design strength and the stone powder content in the manufactured sand. The water consumption per cubic meter of concrete is determined based on the water reduction rate of the admixture. Based on water consumption and water-cement ratio, determine the dosage of cementitious materials, admixtures, fly ash, and slag powder; The amount of cement and manufactured sand used per cubic meter of concrete is determined based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand.

[0006] According to one aspect of the present invention, the calculation of the packing void ratio of graded crushed stone under the most compact packing condition based on a compressible packing model includes: Based on the measured apparent density and bulk density of the graded crushed stone, the actual bulk density of crushed stone of different particle sizes is calculated using the following formula. : ; In the formula, Let be the bulk density of the i-th type of crushed stone; Let be the apparent density of the i-th type of crushed stone; By substituting the actual packing density of crushed stone of different particle sizes into the compressible packing model, the particle size distribution and packing density of the graded crushed stone under the most compact packing state are calculated. Then, the packing porosity of the graded crushed stone under the most compact packing state is calculated according to the following formula: ; In the formula, The porosity is the packing porosity in the most compact packing state. This represents the packing density under the most compact packing condition.

[0007] According to one aspect of the present invention, determining the amount of graded crushed stone and the mortar volume per cubic meter of concrete based on the packing porosity of the graded crushed stone, the thickness of the mortar coating layer, and the air content of the concrete includes: Concrete is composed of mortar, aggregate, and air content, and therefore satisfies the following formula: ; In the formula: This refers to the volume of mortar. For the quality of crushed stone; The apparent density of graded crushed stone; The air content in concrete is taken as the median of the design value for air-entrained concrete, and 1.5% for non-air-entrained concrete. The mortar in concrete consists of two parts: mortar filling the voids in the crushed stone and mortar coating the surface of the crushed stone. Therefore, the following formula applies: ; In the formula: The thickness of the mortar coating layer gradually decreases as the concrete strength increases, ranging from 0.90mm to 1.4mm. The specific surface area of ​​graded crushed stone is calculated using the following formula: ; In the formula: This refers to the particle size distribution of graded crushed stone in its most compacted packing state. Let be the geometric mean of the maximum and minimum particle sizes of particle i in graded crushed stone. This is the aggregate specific surface area correction factor, ranging from 1.0 to 1.15. It is selected based on the degree to which the actual aggregate shape deviates from a spherical shape; the greater the deviation, the larger the value. Based on Japanese style The calculated mass of graded crushed stone used per cubic meter of concrete is: ; Based on this, the volume of mortar in concrete is determined by formula. Calculated.

[0008] According to one aspect of the present invention, the water-cement ratio of the manufactured sand concrete is determined based on the concrete mix design strength and the stone powder content in the manufactured sand as follows: The water-cement ratio of manufactured sand concrete is calculated using the following formula: ; In the formula: W / B is the water-cement ratio of manufactured sand concrete; To prepare the concrete for strength; Cement strength grade; , For regression coefficients, , ; This is the redundancy factor for the cement strength grade value; Let be the influence coefficient of the i-th admixture, where the influence coefficient of the i-th admixture includes the influence coefficient of fly ash, the influence coefficient of mineral powder, and the influence coefficient of manufactured sand and gravel powder.

[0009] According to one aspect of the invention, the water consumption per cubic meter of concrete is determined based on the water reduction rate of the admixture as follows: Under the condition of adding admixtures, the water consumption per cubic meter of concrete is calculated according to the following formula: ; In the formula: Water consumption per cubic meter of concrete; This is the estimated water consumption per cubic meter of concrete to meet the actual slump requirement when no admixtures are added. The water reduction rate is denoted by the admixture.

[0010] According to one aspect of the present invention, the determination of the dosage of cementitious materials, admixtures, and fly ash and slag powder based on water consumption and water-cement ratio is as follows: ; ; ; ; In the formula: The amount of cementitious material used per cubic meter of concrete; The amount of fly ash used per cubic meter of concrete; The amount of slag powder used per cubic meter of concrete; This refers to the dosage of admixtures per cubic meter of concrete. and This refers to the dosage of fly ash and slag powder in cementitious materials.

[0011] According to one aspect of the invention, the amount of cement and manufactured sand used per cubic meter of concrete is determined based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand. ; ; In the formula: The amount of cement used per cubic meter of concrete; The amount of manufactured sand used per cubic meter of concrete; This refers to the density of cement. The apparent density of manufactured sand The density of fly ash; The density of the slag powder; The density of water; The density of the admixture; The content of stone powder in manufactured sand; The density of the manufactured sand and gravel powder; The apparent density of the manufactured sand is given.

[0012] According to the present invention, stone powder in manufactured sand is treated as an inert admixture in cementitious materials. By determining the influence factor of stone powder on the strength of cementitious materials under different stone powder contents, the water-cement ratio of computer-made sand concrete is calculated. Concrete is considered as a material that fills the skeleton formed by coarse aggregate with mortar. In addition to filling the voids formed between aggregates, the mortar also coats the surface of coarse aggregate to ensure the fluidity of concrete, forming a mortar coating layer.

[0013] According to the present invention, the present invention designs concrete mix proportions based on the characteristics of manufactured sand, taking into account the influence of stone powder in manufactured sand on the strength of cementitious materials. Based on this, the calculated concrete water-cement ratio and cementitious material dosage are more reasonable, which can effectively reduce the problem of excessive concrete shrinkage and easy cracking caused by excessive powder content due to traditional design methods. This invention introduces a compressible packing model to calculate the densest packing composition of coarse aggregates, which can significantly save time and manpower spent on aggregate gradation adjustment, effectively ensure that the aggregates in concrete have a small porosity and a more stable packing structure, improve the volume stability and density of concrete, and benefit the long-term durability of concrete. Attached Figure Description

[0014] Figure 1 The flowchart schematically illustrates a method for designing the mix proportions of manufactured sand concrete according to one embodiment of the present invention. Detailed Implementation

[0015] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0016] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0017] Figure 1 A flowchart illustrating a method for designing the mix proportions of manufactured sand concrete according to one embodiment of the present invention is shown. Figure 1 As shown, in this embodiment, the method for designing the mix proportion of manufactured sand concrete includes: The density of cementitious materials, the density of water, the apparent density of manufactured sand, the density of stone powder in manufactured sand, the stone powder content, the apparent density and bulk density of graded crushed stone, and the density and water reduction rate of admixtures were determined respectively. The packing void ratio of graded crushed stone under the most compact packing condition was calculated based on the compressible packing model. Based on the porosity of graded crushed stone, the thickness of the mortar coating layer, and the air content of concrete, the amount of graded crushed stone and the volume of mortar per cubic meter of concrete are determined. The water-cement ratio of manufactured sand concrete is determined based on the concrete mix design strength and the stone powder content in the manufactured sand. The water consumption per cubic meter of concrete is determined based on the water reduction rate of the admixture. Based on water consumption and water-cement ratio, determine the dosage of cementitious materials, admixtures, fly ash, and slag powder; The amount of cement and manufactured sand used per cubic meter of concrete is determined based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand.

[0018] According to one embodiment of the present invention, the calculation of the packing void ratio of graded crushed stone under the most compact packing condition based on a compressible packing model includes: Based on the measured apparent density and bulk density of the graded crushed stone, the actual bulk density of crushed stone of different particle sizes is calculated using the following formula: ; By substituting the actual packing density of crushed stone of different particle sizes into the compressible packing model, the particle size distribution and packing density of the graded crushed stone under the most compact packing state are calculated. Then, the packing porosity of the graded crushed stone under the most compact packing state is calculated according to the following formula: ; In the formula, The porosity is the packing porosity in the most compact packing state. This represents the packing density under the most compact packing condition.

[0019] In this embodiment, the formula for the compressible packing model is as follows: ; ; ; ; In the formula: This refers to the actual bulk density of the particle (crushed stone) mixture; The virtual packing density of the particle mixture when the i-th particle is dominant; and These represent the virtual packing density when particles i and j are packed separately; This is the wall adhesion effect coefficient; The loosening effect coefficient; Let be the volume fraction of particle j in the mixture; K is the compaction factor, which characterizes the degree of influence of different packing methods on the packing density of particle mixtures. The scheme of this invention belongs to natural packing, and K=4.1 is taken.

[0020] and Let $\mathbf{i}$ and $\mathbf{j}$ be the geometric mean of the maximum and minimum particle sizes, respectively, and the formula for their calculation is: .

[0021] According to one embodiment of the present invention, the amount of graded crushed stone and the volume of mortar per cubic meter of concrete are determined based on the packing porosity of the graded crushed stone, the thickness of the mortar coating layer, and the air content of the concrete, including: Concrete is composed of mortar, aggregate, and air content, and therefore satisfies the following formula: ; In the formula: This refers to the volume of mortar. For the quality of crushed stone; The apparent density of graded crushed stone; The air content in concrete is taken as the median of the design value for air-entrained concrete, and 1.5% for non-air-entrained concrete. The mortar in concrete consists of two parts: mortar filling the voids in the crushed stone and mortar coating the surface of the crushed stone. Therefore, the following formula applies: ; In the formula: The thickness of the mortar coating layer gradually decreases as the concrete strength increases, ranging from 0.90mm to 1.4mm. The specific surface area of ​​graded crushed stone is calculated using the following formula: ; In the formula: This refers to the particle size distribution of graded crushed stone in its most compacted packing state. Let be the geometric mean of the maximum and minimum particle sizes of particle i in graded crushed stone. This is the aggregate specific surface area correction factor, ranging from 1.0 to 1.15. It is selected based on the degree to which the actual aggregate shape deviates from a spherical shape; the greater the deviation, the larger the value. Based on Japanese style The calculated mass of graded crushed stone used per cubic meter of concrete is: ; Based on this, the volume of mortar in concrete is determined by formula. Calculated.

[0022] According to one embodiment of the present invention, the water-cement ratio of the manufactured sand concrete is determined based on the concrete mix design strength and the stone powder content in the manufactured sand: The water-cement ratio of manufactured sand concrete is calculated using the following formula: ; In the formula: W / B is the water-cement ratio of manufactured sand concrete; To prepare the concrete for strength; Cement strength grade; , For regression coefficients, , ; The redundancy factor for the cement strength grade value is selected according to Table 5.1.4 in the standard "Specification for Mix Proportion Design of Ordinary Concrete" JGJ55; Let represent the influence coefficient of the i-th admixture, which includes the influence coefficients of fly ash, mineral powder, and manufactured sand and gravel powder. The influence coefficients of fly ash and mineral powder are obtained from Table 5.1.3 of standard JGJ 55, and the influence factors (coefficients) of manufactured sand and gravel powder are selected from Table 1 below: Table 1 Influence coefficient of manufactured sand and gravel powder According to one embodiment of the present invention, the water consumption per cubic meter of concrete is determined based on the water reduction rate of the admixture: Under the condition of adding admixtures, the water consumption per cubic meter of concrete is calculated according to the following formula: ; In the formula: Water consumption per cubic meter of concrete; This is the estimated water consumption per cubic meter of concrete to meet the actual slump requirement when no admixtures are added. The water reduction rate is denoted by the admixture.

[0023] According to one embodiment of the present invention, based on the water consumption and water-cement ratio, the amounts of cementitious materials, admixtures, fly ash, and slag powder are determined as follows: ; ; ; ; In the formula: The amount of cementitious material used per cubic meter of concrete; The amount of fly ash used per cubic meter of concrete; The amount of slag powder used per cubic meter of concrete; This refers to the dosage of admixtures per cubic meter of concrete. and This refers to the dosage of fly ash and slag powder in cementitious materials.

[0024] According to one embodiment of the present invention, based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand, the amount of cement and manufactured sand used per cubic meter of concrete is determined as follows: ; ; In the formula: The amount of cement used per cubic meter of concrete; The amount of manufactured sand used per cubic meter of concrete; This refers to the density of cement. The apparent density of manufactured sand The density of fly ash; The density of the slag powder; The density of water; The density of the admixture; The content of stone powder in manufactured sand; The density of the manufactured sand and gravel powder; The apparent density of the manufactured sand is given.

[0025] According to the above-described scheme of the present invention, stone powder in manufactured sand is treated as an inert admixture in cementitious materials. By determining the influence factor of stone powder on the strength of cementitious materials under different stone powder dosages, the water-cement ratio of computer-made sand concrete is calculated. Concrete is considered as a material that fills the skeleton formed by coarse aggregate with mortar. In addition to filling the voids formed between aggregates, in order to ensure the fluidity of concrete, part of the mortar also coats the surface of the coarse aggregate, forming a mortar coating layer.

[0026] According to the above-described scheme of the present invention, the present invention designs concrete mix proportions based on the characteristics of manufactured sand, taking into account the influence of stone powder in manufactured sand on the strength of cementitious materials. Based on this, the calculated concrete water-cement ratio and cementitious material dosage are more reasonable, which can effectively reduce the problem of excessive concrete shrinkage and easy cracking caused by excessive powder content due to traditional design methods. This invention introduces a compressible packing model to calculate the densest packing composition of coarse aggregates, which can significantly save time and manpower spent on aggregate gradation adjustment, effectively ensure that the aggregates in concrete have a small porosity and a more stable packing structure, improve the volume stability and density of concrete, and benefit the long-term durability of concrete.

[0027] Based on the above-described solution of the present invention, the solution of the present invention will be described in detail below by way of specific embodiments.

[0028] Example 1 This embodiment provides a C35 manufactured sand concrete for use in the side walls, top beams, and top slabs of subway engineering, with a slump requirement of (150±30) mm. The raw materials are as follows: the cement is P·O42.5R cement with a density of 3150 kg / m³. 3 The 28-day compressive strength is 50.3 MPa; the fly ash grade is Class F, Grade II, and the density is 2500 kg / m³. 3 The slag powder is grade S95 with a density of 2900 kg / m³. 3 The recommended dosage of the water-reducing agent is 2.0%, the water reduction rate is 27%, and the density is 1.02 g / cm³. 3 The apparent density of manufactured sand is 2650 kg / m³. 3 The stone powder content is 7%; the crushed stone adopts a two-stage mix design, and the apparent density is 2650 kg / m³. 3 The bulk density of the 5-16mm crushed stone is 1420kg / m³. 3 The bulk density of 16-31.5mm crushed stone is 1410kg / m³. 3 .

[0029] Based on the compressible packing model, the virtual packing density of 5-16mm crushed stone is 0.536, and the virtual packing density of 16-31.5mm crushed stone is 0.532. It is calculated that when the coarse aggregate is in the most compact packing state, the volume ratio of 5-16mm crushed stone is 44%, the volume ratio of 16-31.5mm crushed stone is 56%, the packing density of crushed stone is 0.592, and the packing porosity is 0.408.

[0030] The specific surface area of ​​the crushed stone was calculated, and a correction factor of 1.12 was used. The calculated specific surface area of ​​the crushed stone was 0.188 m². 2 / kg.

[0031] Assuming an air content of 1.5% per cubic meter of concrete and a mortar coating thickness of 1.0 mm, calculate the mortar volume and aggregate mass per cubic meter of concrete: ; ; ; ; The fly ash content is 15%, and the influence coefficient is taken. The coefficient is 0.87, the slag powder content is 10%, and the influence coefficient is taken as 0.87. Given a coefficient of 1.00, a stone powder content of 7% in the manufactured sand, and an admixture of approximately 15% in the cementitious materials, with an influence coefficient of 0.90, the water-cement ratio of the concrete is calculated as follows: ; Taking the upper limit of the design value of concrete slump as 180mm, and referring to the table, the estimated water consumption per cubic meter of concrete to meet the actual slump requirement without admixtures is 228kg / m³. 3 Based on the water reduction rate of the water-reducing agent (admixture), the water consumption per cubic meter of concrete is calculated as follows: ; The calculated amount of cementitious material used per cubic meter of concrete is 384 kg / m³. 3 The fly ash usage is 58 kg / m³. 3 The amount of slag powder used is 38 kg / m³. 3 The water-reducing agent dosage is 7.68 kg / m³. 3 .

[0032] The amount of cement and manufactured sand used per cubic meter of concrete is calculated as follows: ; ; Solving for cement usage 231 kg / m3 Manufactured sand usage It is 812 kg / m 3 .

[0033] The performance of the manufactured sand concrete designed using this invention is compared with that of the manufactured sand concrete designed according to standard JGJ 55. The concrete mix design is shown in Table 2, and the concrete performance is shown in Table 3.

[0034] Table 2 Mix Proportions for C35 Manufactured Sand Concrete Table 3 Performance of C35 manufactured sand concrete As shown in Table 3, the strength of the C35 concrete designed using this invention is lower than that designed according to standard JGJ 55, but it still meets the strength requirements for concrete mix design. Meanwhile, its workability, shrinkage resistance, and chloride ion penetration resistance are all superior to the latter. In summary, the mix design method provided by this invention is more suitable for manufactured sand concrete, enabling manufactured sand concrete to achieve low shrinkage and high durability while meeting the strength and workability requirements.

[0035] Example 2 This embodiment provides a C50 manufactured sand concrete for use in precast small box girders of bridge engineering. The slump requirement is (150±30) mm. The raw materials used are the same as in Embodiment 1. The mortar coating thickness is 0.95 mm, the fly ash content is 20%, the slag powder content is 10%, the water-reducing agent content is increased to 2.4%, and the water reduction rate is 31%. The mix proportion of the C50 manufactured sand concrete designed according to the present invention and the standard is shown in Table 4, and the concrete performance is shown in Table 5.

[0036] Table 4 Mix Proportions for C50 Manufactured Sand Concrete Table 5 Performance of C50 manufactured sand concrete As can be seen from Table 5, the overall performance of the manufactured sand concrete designed using the present invention is superior to that designed according to standard JGJ 55.

[0037] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for designing the mix proportions of manufactured sand concrete, characterized in that, include: The packing void ratio of graded crushed stone under the most compact packing condition was calculated based on the compressible packing model. Based on the porosity of graded crushed stone, the thickness of the mortar coating layer, and the air content of concrete, the amount of graded crushed stone and the volume of mortar per cubic meter of concrete are determined. The water-cement ratio of manufactured sand concrete is determined based on the concrete mix design strength and the stone powder content in the manufactured sand. The water consumption per cubic meter of concrete is determined based on the water reduction rate of the admixture. Based on water consumption and water-cement ratio, determine the dosage of cementitious materials, admixtures, fly ash, and slag powder; The amount of cement and manufactured sand used per cubic meter of concrete is determined based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand.

2. The method for designing the mix proportion of manufactured sand concrete according to claim 1, characterized in that, The calculation of the packing void ratio of graded crushed stone under the most compact packing condition based on the compressible packing model includes: Based on the measured apparent density and bulk density of the graded crushed stone, the actual bulk density of crushed stone of different particle sizes is calculated using the following formula. : ； In the formula, Let be the bulk density of the i-th type of crushed stone; Let be the apparent density of the i-th type of crushed stone; By substituting the actual packing density of crushed stone of different particle sizes into the compressible packing model, the particle size distribution and packing density of the graded crushed stone under the most compact packing state are calculated. Then, the packing porosity of the graded crushed stone under the most compact packing state is calculated according to the following formula: ； In the formula, The porosity is the packing void ratio under the most compact packing condition. This represents the packing density under the most compact packing condition.

3. The method for designing the mix proportion of manufactured sand concrete according to claim 2, characterized in that, The determination of the amount of graded crushed stone and the volume of mortar per cubic meter of concrete based on the packing porosity of the graded crushed stone, the thickness of the mortar coating layer, and the air content of the concrete includes: Concrete is composed of mortar, aggregate, and air content, and therefore satisfies the following formula: ； In the formula: This refers to the volume of mortar. For the quality of crushed stone; The apparent density of graded crushed stone; The air content in concrete is taken as the median of the design value for air-entrained concrete, and 1.5% for non-air-entrained concrete. The mortar in concrete consists of two parts: mortar filling the voids in the crushed stone and mortar coating the surface of the crushed stone. Therefore, the following formula applies: ； In the formula: The thickness of the mortar coating layer gradually decreases as the concrete strength increases, ranging from 0.90mm to 1.4mm. The specific surface area of ​​graded crushed stone is calculated using the following formula: ； In the formula: This refers to the particle size distribution of graded crushed stone in its most compacted packing state. Let be the geometric mean of the maximum and minimum particle sizes of particle i in graded crushed stone. This is the aggregate specific surface area correction factor, ranging from 1.0 to 1.

15. It is selected based on the degree to which the actual aggregate shape deviates from a spherical shape; the greater the deviation, the larger the value. Based on Japanese style The calculated mass of graded crushed stone used per cubic meter of concrete is: ； Based on this, the volume of mortar in concrete is determined by formula. Calculated.

4. The method for designing the mix proportion of manufactured sand concrete according to claim 3, characterized in that, Based on the concrete mix design strength and the stone powder content in the manufactured sand, the water-cement ratio of the manufactured sand concrete is determined as follows: The water-cement ratio of manufactured sand concrete is calculated using the following formula: ； In the formula: W / B is the water-cement ratio of manufactured sand concrete; To prepare the concrete for strength; Cement strength grade; , For regression coefficients, , ; This is the redundancy factor for the cement strength grade value; Let be the influence coefficient of the i-th admixture, where the influence coefficient of the i-th admixture includes the influence coefficient of fly ash, the influence coefficient of mineral powder, and the influence coefficient of manufactured sand and gravel powder.

5. The method for designing the mix proportion of manufactured sand concrete according to claim 4, characterized in that, Based on the water reduction rate of the admixture, the water consumption per cubic meter of concrete is determined as follows: Under the condition of adding admixtures, the water consumption per cubic meter of concrete is calculated according to the following formula: ； In the formula: Water consumption per cubic meter of concrete; This is the estimated water consumption per cubic meter of concrete to meet the actual slump requirement when no admixtures are added. The water reduction rate is denoted by the admixture.

6. The method for designing the mix proportion of manufactured sand concrete according to claim 5, characterized in that, The amounts of cementitious materials, admixtures, fly ash, and slag powder are determined based on water consumption and water-cement ratio as follows: ； ； ； ； In the formula: The amount of cementitious material used per cubic meter of concrete; The amount of fly ash used per cubic meter of concrete; The amount of slag powder used per cubic meter of concrete; This refers to the dosage of admixtures per cubic meter of concrete. and This refers to the dosage of fly ash and slag powder in cementitious materials.

7. The method for designing the mix proportion of manufactured sand concrete according to claim 6, characterized in that, Based on the mortar volume, the stone powder content in the manufactured sand, the density of the stone powder in the manufactured sand, and the apparent density of the manufactured sand, the amount of cement and manufactured sand used per cubic meter of concrete is determined as follows: ； ； In the formula: The amount of cement used per cubic meter of concrete; The amount of manufactured sand used per cubic meter of concrete; This refers to the density of cement. The apparent density of manufactured sand The density of fly ash; The density of the slag powder; The density of water; The density of the admixture; The content of stone powder in manufactured sand; The density of the manufactured sand and gravel powder; The apparent density of the manufactured sand is given.

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