A mix design method for cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control

Abstract

The present invention relates to a mix ratio design method for cast-in-place concrete with machine-made sand and gravel aggregates based on shrinkage control, comprising the following steps: 1) according to the characteristics of cast-in-place concrete with machine-made sand and gravel aggregates, low shrinkage is determined as the main design goal; 2) based on the prediction model of concrete shrinkage and elastic modulus, the relationship between concrete shrinkage and aggregates, interfaces and pastes is established; 3) the material selection principle and optimization technology for raw materials used for low shrinkage concrete are clarified. The present invention innovates the mix ratio design method for cast-in-place concrete with machine-made sand and gravel aggregates based on shrinkage control. The prepared cast-in-place concrete with machine-made sand and gravel aggregates has good workability, mechanical properties and durability, has the characteristics of low shrinkage and good shrinkage matching of different components of concrete, can better serve in major projects such as high-speed railways, and greatly reduces the cracking ability of cast-in-place concrete structures.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a mix ratio design method of cast-in-place concrete with machine-made sand and gravel aggregates based on shrinkage control. Background Art

[0002] With the steady advancement of the engineering development strategy in my country's construction field, major projects such as railways and highways have developed rapidly. However, due to the policy of limiting the extraction of river sand resources and seasonal effects, there is a serious shortage of river sand raw materials for concrete that meet the requirements, especially in mountainous projects mainly in Yunnan, Guizhou and Sichuan. This not only causes unstable quality and rising prices of raw materials, but also affects the construction period of the project. In severe cases, it leads to insufficient durability and quality decline of the project, affecting the service performance and service life of the project. The application of machine-made sand and gravel aggregate is the main measure to solve the difficulty of using sand for concrete, and it is also an important direction for the development of green building materials.

[0003] At present, there are many studies on machine-made sand and gravel aggregates in cast-in-place concrete for railways. The research results show that it is feasible to use machine-made sand and gravel aggregates in cast-in-place concrete components for railways, but there are few studies on the shrinkage of machine-made sand and gravel aggregate cast-in-place concrete for railways. In recent years, Li Huajian and others from the China Academy of Railway Sciences have systematically studied the performance of machine-made sand and gravel aggregate cast-in-place concrete for railways, including cast-in-place piles, pier caps, tunnel linings and other machine-made sand and gravel aggregate cast-in-place concrete structures, but have not proposed a mix design method for machine-made sand and gravel aggregate cast-in-place concrete based on shrinkage control. Chinese patent CN 109369097 A "A low-shrinkage, low-shrinkage, crack-resistant, high-performance large-volume concrete", Chinese patent CN 102701654 B "A type of low-shrinkage concrete", Chinese patent CN 103011727 B "A low-shrinkage concrete" and Chinese patent CN 105461274 B "A low-shrinkage concrete" disclose the formula of low-shrinkage concrete, but these patents lack theoretical support and guidance, lack consideration of the shrinkage matching of different components of concrete, and lack research on the shrinkage of machine-made sand concrete. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to invent a method for designing the mix ratio of cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control.

[0005] The object of the present invention can be achieved by the following technical scheme: a method for designing mix proportion of cast-in-place concrete with machine-made sand and gravel aggregates based on shrinkage control, characterized in that the method comprises the following steps: 1) according to the characteristics of cast-in-place concrete with machine-made sand and gravel aggregates, low shrinkage is determined as the main design goal; 2) based on the prediction model of concrete shrinkage and elastic modulus, the relationship between concrete shrinkage and aggregate, interface and paste is established; 3) the selection principle and optimization technology of raw materials for low shrinkage concrete are clarified.

[0006] In step 1), the cast-in-place concrete with machine-made sand and gravel aggregate is removed after one day of molding, and the shrinkage value after 360 days of curing is tested, which mainly includes three levels: Level I is a shrinkage of less than 350×10 -6 , The shrinkage level is between 350×10 -6 ~450×10 -6 , The shrinkage is greater than 450×10 -6 .

[0007] Preferably, the low shrinkage grade is grade I.

[0008] In the step 2), the relationship between the shrinkage of concrete and the aggregate, interface and paste is established mainly based on the combination of a shrinkage prediction model of concrete elastic modulus, a concrete elastic modulus prediction model based on the elastic modulus of aggregate and paste, and a paste elastic modulus prediction model based on the compressive strength of paste.

[0009] Preferably, the calculation formula of the shrinkage prediction model based on the elastic modulus of concrete in step 2) is:

[0010] ε sh (t, t0) = -k h S(t)ε s∞ 607E t / (t0+τ sh ) (1)

[0011] Where ε sh (t, t0) is the shrinkage of the concrete structure at age t, t is the age of concrete shrinkage test, t0 is the age of starting drying, k h is the environmental correction factor, E t is the elastic modulus of concrete at age t, ε s∞ and τ sh It is a coefficient related to the thickness, axial compressive strength, shape and moisture content of concrete.

[0012] Preferably, the calculation formula of the concrete elastic modulus prediction model based on the elastic modulus of aggregate and paste in step 2) is:

[0013] Et =E m V m +E g V g (2)

[0014] Where E m 、E g are the elastic modulus of paste and aggregate, V m 、V g are the volume fractions of paste and aggregate, respectively, and V m +V g =1.

[0015] Preferably, the calculation formula of the slurry elastic modulus prediction model based on the slurry compressive strength in step 3) is:

[0016] E m =4.0279σ s 0.1794 (3)

[0017] Where σ s is the compressive strength of the slurry.

[0018] Combining equations (1) to (3), we can get:

[0019] ε sh (t, t0) = -k h S(t)ε s∞ 607 (4.0279σ s 0.1794 V m +E g V g ) / (t0+τ sh ) (4)

[0020] Equation (4) establishes the relationship between concrete shrinkage and aggregate, interface and paste.

[0021] The material selection principles and optimization techniques for the low shrinkage concrete in step 3) are mainly aimed at aggregates, interfaces and pastes.

[0022] Preferably, the principle of aggregate selection in step 3) is to select coarse aggregate with moderate elastic modulus and particle size, good particle shape and gradation, and to select machine-made sand with good particle shape, gradation, low MB value and moderate stone powder content.

[0023] Further preferably, the moderate elastic modulus is 50 GPa to 100 GPa, the uniaxial compressive strength is 60 MPa to 100 MPa, and the coarse aggregate is mainly one of plagioclase granite, porphyritic granite, gneissic granite, quartz sandstone, syenite, granite, andesite and limestone.

[0024] Further preferably, the machine-made sand and gravel aggregate is continuously graded from 0 mm to 20 mm, and its fineness modulus is from 4.6 to 6.0.

[0025] Further preferably, the coarse aggregate particle shape is preferably that the roundness of the coarse aggregate is greater than 0.8, and the needle-like content is less than 5% of the total mass of the coarse aggregate.

[0026] Further preferably, the grain shape of the machine-made sand preferably has a roundness greater than 0.85 and an aspect ratio less than 1.5.

[0027] Further preferably, the machine-made sand is graded as medium sand in zone II.

[0028] Further preferably, the MB value of the machine-made sand is less than 1.4, and the stone powder content is less than 10%.

[0029] Preferably, the interface optimization technology in step 3) is to reduce the thickness of the interface transition zone and reduce the porosity of the interface transition zone.

[0030] Further preferably, the reduction of the thickness and porosity of the interface transition zone is mainly achieved by using one or more of a lower water-binder ratio, adding a water reducing agent, and adding a large amount of silicon-based material.

[0031] More preferably, the lower water-to-binder ratio is between 0.35 and 0.45.

[0032] More preferably, the water reducer is a polycarboxylic acid high-efficiency water reducer.

[0033] More preferably, the silicon-based material is one or more of fly ash, silica ash, rice husk ash, slag powder, and metakaolin.

[0034] Preferably, the material selection principle of the slurry in step 3) is to add mineral admixtures that significantly improve the elastic modulus of the slurry, and the optimization technology is to increase the gas content of the slurry and improve the volume fraction of the slurry.

[0035] Further preferably, the mineral admixture that significantly improves the elastic modulus of the slurry is an ultrafine mineral admixture that can increase the calcium-silicon ratio in the cement slurry.

[0036] More preferably, the mineral admixture added to increase the calcium-silicon ratio in the cement paste is calcium carbonate powder.

[0037] More preferably, the ultrafine mineral admixture is mainly one or more of nano silicon dioxide and ground stone powder.

[0038] Further preferably, the increasing of the slurry air content is to control the air content of the concrete to be less than 4%;

[0039] More preferably, the increase in the air content of the slurry can be achieved by using an air entraining agent.

[0040] More preferably, the slurry volume fraction is 25% to 35%.

[0041] The cast-in-place concrete with sand and gravel aggregate based on shrinkage control mechanism is composed of the same lithology aggregate and stone powder admixture supplemented with cementitious materials, water, admixtures, etc., and is prepared by the following components in parts by weight:

[0042] Cement with strength grade >42.5 100,

[0043] Specific surface area not less than 400m 2 / kg finely ground stone powder 10-20,

[0044] Mineral admixture 10-55,

[0045] 0mm~20mm continuous graded mixed machine-made sand and gravel aggregate 376-416,

[0046] Polycarboxylic acid high efficiency water reducing agent 0.4-1.0,

[0047] Air entraining agent 0.01-0.05,

[0048] Water 42-85.5.

[0049] The preparation method comprises the following steps: adding cementitious material and machine-made sand and gravel aggregate into a mixer in proportion, forcing stirring for 60 seconds, adding 3 / 4 water and admixture to the obtained mixture, forcing stirring for 60 seconds, and then adding 1 / 4 water and admixture to the obtained mixture, forcing stirring for 60 seconds to 180 seconds to obtain a concrete mixture.

[0050] Compared with the prior art, the present invention has the following advantages: (1) Quantitative design of low shrinkage of machine-made sand and gravel aggregate. Previous inventions have little research on the shrinkage of cast-in-place concrete with machine-made sand and gravel aggregate, and the shrinkage of concrete prepared by the disclosed invention patents is still relatively high, which cannot meet the design goal of low-shrinkage grade cast-in-place concrete with machine-made sand and gravel aggregate. The present invention is based on theoretical design, material selection and optimization techniques to quantitatively design low-shrinkage cast-in-place concrete with machine-made sand and gravel aggregate. (2) The material selection principle is appropriate and reliable. On the basis of giving priority to the design of low-shrinkage cast-in-place concrete with machine-made sand and gravel aggregate, the difference in shrinkage between different components of concrete is also considered, which is not considered by other invention patents and is also a very important characteristic affecting concrete cracking. The present invention reduces the differences in elastic modulus and thermodynamic properties of different components by optimizing raw materials. (3) The mix design method is advanced. The mix design concept of the present invention is that the same rock type sand and gravel aggregate and stone powder admixture are supplemented with cementitious materials, water, admixtures, etc. From the perspective of powder modification, key index requirements of machine-made sand, key index control of coarse aggregate, and optimization of mineral admixtures, based on relevant theoretical support, the mix design of cast-in-place concrete with machine-made sand and gravel aggregate is proposed through different components and different scales. The method is extremely advanced.

[0051] The principle of a mix design method for cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control is as follows:

[0052] The purpose of a mix design method for cast-in-place concrete with manufactured sand and gravel aggregate based on shrinkage control is to match the elastic modulus of different components on the basis of meeting the overall low shrinkage design target of concrete. For this purpose, a prediction model of shrinkage of cast-in-place concrete with manufactured sand and gravel aggregate related to aggregate, interface and paste is established as follows:

[0053] ε sh (t, t0) = -k h S(t)ε s∞ 607 (4.0279σ s 0.1794 V m +E g V g ) / (t0+τ sh )

[0054] Where ε sh (t, t0) is the shrinkage of the concrete structure at age t, t is the age of concrete shrinkage test, t0 is the age of starting drying, k h is the environmental correction factor, E t is the elastic modulus of concrete at age t, ε s∞ and τ sh is a coefficient related to the thickness, axial compressive strength, shape and moisture content of concrete, E m 、E gare the elastic modulus of paste and aggregate, V m 、V g are the volume fractions of paste and aggregate, respectively, and V m +V g =1,σ s is the compressive strength of the slurry.

[0055] Based on the optimization theoretical prediction model of low shrinkage of concrete, the elastic modulus of concrete is divided into three parts: aggregate, interface and paste, which can better establish the relationship between concrete shrinkage and concrete raw materials.

[0056] As for aggregates, in concrete, aggregates occupy a large volume fraction and play the role of skeleton. Moreover, the elastic modulus of aggregates is very high, so the elastic modulus of aggregates has a significant influence on the elastic modulus of concrete. g The larger the volume fraction V g The larger the coarse aggregate, the greater the elastic modulus of concrete and the lower its shrinkage; and the larger the maximum particle size of the coarse aggregate and the better the gradation, the larger its volume fraction can also be, thereby increasing the elastic modulus of concrete. The present invention does not pursue too low shrinkage. On the basis of obtaining a lower shrinkage, it tries to match the shrinkage of different components as much as possible. Therefore, the elastic modulus, maximum particle size and volume fraction of the coarse aggregate all need to be moderate. For machine-made sand, selecting machine-made sand with better particle shape and gradation, lower MB value and moderate stone powder content helps to improve the workability of concrete.

[0057] For the interface, it is a key factor affecting the reduction of the elastic modulus of concrete. In order to match the elastic modulus of aggregate as much as possible, the elastic modulus of the interface can be improved by reducing the thickness and porosity of the interface transition zone. Specifically, measures such as using a lower water-binder ratio or adding silicon-based mineral admixtures can be used to improve it. The main mechanism is to reduce the moisture, porosity and calcium hydroxide content in the transition zone.

[0058] For the paste, it is mainly composed of CSH gel and pores, so the improvement of its elastic modulus is mainly achieved by increasing the calcium-silicon ratio in the cement paste to improve the elastic modulus of the CSH gel. The addition of ultrafine stone powder and mineral admixtures can play the role of crystal nuclei to promote hydration and fill the pores of cement stone, thereby promoting the improvement of the elastic modulus of the paste. Increasing the volume fraction of the paste is conducive to achieving excellent workability of the concrete, and higher mineral material substitution in the paste can significantly reduce the amount of cement used and reduce concrete shrinkage.

[0059] Through the above-mentioned raw material selection principles and optimization technology, low-shrinkage cast-in-place concrete with machine-made sand and gravel aggregates can be formulated. At the same time, based on the characteristics that the elastic modulus of coarse aggregate is relatively high, while the elastic modulus of slurry and interface is relatively low, the present invention matches the difference in elastic modulus between different components in mix design by increasing the elastic modulus of the interface and slurry, and matches the elastic modulus of sand and gravel powder by using stone, sand and powder of the same lithology. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0061] Figure 1 The present invention is a flow chart of a method for designing a mix ratio of cast-in-place concrete with machine-made sand and gravel aggregates based on deformation control. DETAILED DESCRIPTION

[0062] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. These embodiments are only intended to illustrate the present invention but not to limit the scope of the present invention.

[0063] Example 1: Among the raw materials, cement is P.O42.5 grade, and the cement dosage is 270kg / m 3 The water-cement ratio is 0.36, the coarse aggregate is andesite, the machine-made sand and gravel aggregate is 0mm~20mm continuous grading, its fineness modulus is 5.2, the roundness of the coarse aggregate is 0.81, the needle-like content is 4%, the fine aggregate is andesite machine-made sand, the grading is II zone medium sand, the MB value is 1.2, the stone powder content is 5%, the roundness of the machine-made sand is 0.86, the aspect ratio is 1.38, the fly ash is II grade fly ash, and the dosage is 90kg / m 3 The amount of rice husk ash is 70kg / m 3 The specific surface area of ​​ground andesite powder is 450m 2 / kg, dosage is 30kg / m 3 , the gas content is 3%, and the slurry volume fraction is 25%.

[0064] Add cementitious materials and machine-made sand and gravel aggregates to the mixer in proportion, force stirring for 60s, add 3 / 4 water and admixtures to the resulting mixture, force stirring for 60s, then add 1 / 4 water and admixtures to the resulting mixture, force stirring for 60s to 180s to obtain a concrete mixture. The size of the concrete is 100mm×100mm×400mm. After pouring and forming for 1d, the mold is removed and moved into a constant temperature and constant temperature room with a temperature of 20±2℃ and a relative humidity of 60±5%, and the drying shrinkage of the concrete is tested for 360d.

[0065] Example 2: Among the raw materials, cement is P.O42.5 grade, and the amount of cement is 250kg / m 3 The water-cement ratio is 0.39, the coarse aggregate is plagioclase granite, the machine-made sand and gravel aggregate is 0mm~20mm continuous gradation, its fineness modulus is 5.4, the roundness of the coarse aggregate is 0.83, the needle-like content is 4%, the fine aggregate is plagioclase granite machine-made sand, the grading is II zone medium sand, MB value is 1.0, the stone powder content is 6%, the roundness of the machine-made sand is 0.88, the aspect ratio is 1.36, the volume fraction of the aggregate is 80%, the fly ash is II grade fly ash, and the dosage is 80kg / m 3 , the amount of rice husk ash is 60kg / m 3 The specific surface area of ​​the ground plagioclase granite powder is 450m 2 / kg, dosage is 25kg / m 3 , the dosage of nano silicon dioxide is 10kg / m 3 , the gas content is 3.5%, and the volume fraction of slurry is 30%.

[0066] Add cementitious materials and machine-made sand and gravel aggregates to the mixer in proportion, force stirring for 60s, add 3 / 4 water and admixtures to the resulting mixture, force stirring for 60s, then add 1 / 4 water and admixtures to the resulting mixture, force stirring for 60s to 180s to obtain a concrete mixture. The size of the concrete is 100mm×100mm×400mm. After pouring and forming for 1d, the mold is removed and moved into a constant temperature and constant temperature room with a temperature of 20±2℃ and a relative humidity of 60±5%, and the drying shrinkage of the concrete is tested for 360d.

[0067] Example 3: Among the raw materials, cement is P.O42.5 grade, and the cement dosage is 210kg / m 3 The water-cement ratio is 0.39, the coarse aggregate is limestone, the machine-made sand and gravel aggregate is 0mm~20mm continuous grading, its fineness modulus is 5.5, the roundness of the coarse aggregate is 0.85, the needle-like content is 4%, the fine aggregate is limestone machine-made sand, the grading is II zone medium sand, the MB value is 0.8, the stone powder content is 7%, the roundness of the machine-made sand is 0.92, the aspect ratio is 1.32, and the I-level fly ash is 30kg / m 3 , the amount of rice husk ash is 50kg / m 3 , the dosage of kaolin is 50kg / m 3 The specific surface area of ​​limestone powder is 400m 2 / kg, dosage is 20kg / m 3 , the dosage of nano silicon dioxide is 10kg / m 3 , the gas content is 3.5%, and the volume fraction of slurry is 35%.

[0068] Add cementitious materials and machine-made sand and gravel aggregates to the mixer in proportion, force stirring for 60s, add 3 / 4 water and admixtures to the resulting mixture, force stirring for 60s, then add 1 / 4 water and admixtures to the resulting mixture, force stirring for 60s to 180s to obtain a concrete mixture. The size of the concrete is 100mm×100mm×400mm. After pouring and forming for 1d, the mold is removed and moved into a constant temperature and constant temperature room with a temperature of 20±2℃ and a relative humidity of 60±5%, and the drying shrinkage of the concrete is tested for 360d.

[0069] The measured properties of the low shrinkage machine-made sand and gravel aggregate cast-in-place concrete mix design provided in Examples 1 to 3 and the comparative machine-made sand and gravel aggregate cast-in-place concrete mix design are shown in Tables 1 and 2.

[0070] Table 1 Performance test of cast-in-place concrete with different mix ratios of machine-made sand and gravel aggregate

[0071]

[0072] Table 2 Shrinkage performance test of cast-in-place concrete with different mix ratios of manufactured sand and gravel aggregate

[0073]

[0074] As can be seen from Table 1, the concrete prepared in Example 3 has good working performance and fully meets the construction requirements of cast-in-place concrete. As can be seen from Table 2, compared with the cast-in-place concrete with machine-made sand and gravel aggregate designed by the comparative mix ratio, the difference in elastic modulus of different components of the concrete in Examples 1 to 3 is relatively small, and it can be seen that the shrinkage between the different components of these groups of concrete is relatively uniform, and the internal stress concentration of the concrete is weakened. Further analysis shows that Example 3 not only has a small shrinkage, but also the elastic modulus between the components is closer, which meets the design objectives of the present invention, is conducive to the long-term and safe use of cast-in-place concrete with machine-made sand and gravel aggregate, and is not easy to crack.

Claims

1. A method for designing mix proportion of cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control, characterized in that: The following steps are involved: 1) According to the characteristics of cast-in-place concrete with machine-made sand and gravel aggregate, low shrinkage is determined as the design goal; 2) Based on the prediction model of concrete shrinkage and elastic modulus, the relationship between concrete shrinkage and aggregate, interface and paste was established; 3) The selection principle and optimization technology of raw materials for low shrinkage concrete were clarified; The relationship between the shrinkage of concrete and the aggregate, interface and paste in the step 2) is established by combining a shrinkage prediction model based on the elastic modulus of concrete, a concrete elastic modulus prediction model based on the elastic modulus of aggregate and paste, and a paste elastic modulus prediction model based on the compressive strength of paste; The calculation formula of the shrinkage prediction model based on the concrete elastic modulus in step 2) is: Ε sh (t,t0)=-k h S(t)ε s∞ 607E t / (t0+τ sh ) (1) Where ε sh (t, t0) is the shrinkage of the concrete structure at age t, t is the age of concrete shrinkage test, t0 is the starting drying age, k h is the environmental correction factor, E t is the elastic modulus of concrete at age t, ε s∞ and τ sh is a coefficient related to the thickness, axial compressive strength, shape and moisture content of concrete; The calculation formula of the concrete elastic modulus prediction model based on the elastic modulus of aggregate and paste is: E t =E m V m +E g V g (2) Where E m 、E g are the elastic modulus of paste and aggregate, V m 、V g are the volume fractions of paste and aggregate, respectively, and V m +V g =1; The calculation formula of the slurry elastic modulus prediction model based on the slurry compressive strength is: E m =4.0279σ s 0.1794 (3) Where σ s is the compressive strength of the slurry; Combining equations (1) to (3), we can get: e sh (t,t0)=-k h S(t)e s∞ 607(4.0279s s 0.1794 V m +E g V g ) / (t0+τ sh ) (4) Formula (4) establishes the relationship between concrete shrinkage and aggregate, interface and paste; The material selection principles and optimization techniques for low shrinkage concrete in step 3) are aimed at aggregates, interfaces and pastes; The specific indicators of the material selection principle of the machine-made sand and gravel aggregate in the step 3) are as follows: the elastic modulus of the parent rock of the machine-made sand and gravel aggregate is 50-100GPa, the uniaxial compressive strength is 60-100Mpa, the parent rock is one of plagioclase granite, porphyritic granite, gneissic granite, quartz sandstone, syenite, granite, andesite and limestone, the machine-made sand and gravel aggregate is 0-20mm continuous gradation, and its fineness modulus is 4.6-6.0; the roundness of the coarse aggregate is greater than 0.8, and the needle-like content is less than 5% of the total mass of the coarse aggregate; the particle shape of the machine-made sand is a roundness greater than 0.85, the aspect ratio is less than 1.5, the machine-made sand gradation is medium sand in zone II, the MB value of the machine-made sand is less than 1.4, and the stone powder content is less than 10%; The interface optimization technology in step 3) is to reduce the thickness and porosity of the interface transition zone. The specific optimization technology is as follows: by using a water-binder ratio of 0.35 to 0.45, adding a polycarboxylic acid high-efficiency water reducer and adding one or more of silicon-based materials, wherein the silicon-based material is one or more of fly ash, silica fume, rice husk ash, slag powder, and metakaolin materials; The material selection principle and optimization technology of the slurry in step 3) is to add mineral admixtures that significantly improve the elastic modulus of the slurry and reduce the gas content of the slurry. The specific material selection principles and optimization technologies are as follows: add one or more of calcium carbonate powder, nano-silicon dioxide, and ground stone powder.

2. The method for designing mix proportion of cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control according to claim 1 is characterized in that: In the step 1), the cast-in-place concrete with machine-made sand and gravel aggregate is removed after being formed for 1 day, and the shrinkage value after curing for 360 days is tested, including three levels: Level I is a shrinkage of less than 350×10 -6 , Grade II is the shrinkage between 350×10-6~450×10 -6 , Grade III is the shrinkage greater than 450×10 -6 .

3. The method for designing mix proportion of cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control according to claim 1 is characterized in that: The gas content of the slurry is increased by using an air-entraining agent and controlling the gas content to be less than 4% and the slurry volume fraction to be 25% to 35%.

4. The method for designing mix proportion of cast-in-place concrete with machine-made sand and gravel aggregate based on shrinkage control according to claim 1 is characterized in that: The cast-in-place concrete based on shrinkage-controlled machine-made sand and gravel aggregate is composed of machine-made sand and gravel aggregate of the same lithology and stone powder admixture supplemented with cementitious materials, water, and admixtures, and is prepared by the following components in parts by weight:

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