CN111724869A - Shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method - Google Patents
Shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method Download PDFInfo
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- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C60/00—Computational materials science, i.e. ICT specially adapted for investigating the physical or chemical properties of materials or phenomena associated with their design, synthesis, processing, characterisation or utilisation
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/18—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mixtures of the silica-lime type
-
- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/10—Analysis or design of chemical reactions, syntheses or processes
-
- G—PHYSICS
- G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
- G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- G16C20/00—Chemoinformatics, i.e. ICT specially adapted for the handling of physicochemical or structural data of chemical particles, elements, compounds or mixtures
- G16C20/30—Prediction of properties of chemical compounds, compositions or mixtures
Abstract
The invention relates to a shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method, which comprises the following steps: 1) determining low shrinkage as a main design target according to the characteristics of the machine-made sandstone aggregate cast-in-place concrete; 2) establishing the relation between the concrete shrinkage and aggregate, an interface and slurry based on a prediction model of the concrete shrinkage and the elastic modulus; 3) the material selection principle and the optimization technology of the raw materials for the low-shrinkage concrete are defined. The invention innovating a shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method, the prepared machine-made sandstone aggregate cast-in-place concrete has good workability, mechanical property and durability, has the characteristics of low shrinkage and good shrinkage matching of different components of concrete, can be better used in heavy projects such as high-speed railways and the like, and greatly reduces the cracking capacity of cast-in-place concrete structures.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method.
Background
With the steady advance of engineering development strategies in the building field of China, major projects such as railways and highways are developed rapidly and are influenced by river sand resource mining-limiting policies and seasonality, river sand raw materials for concrete which meet requirements are in serious shortage, and mountain projects mainly in cloud, noble and river regions are particularly remarkable. This not only causes unstable quality and price rise of raw materials, but also affects construction period of projects, and in severe cases, causes insufficient durability and quality reduction of projects, and affects service performance and service life of projects. The application of the machine-made sandstone aggregate is a main measure for solving the difficulty of using the sand for the concrete and is an important direction for developing green building materials.
At present, machine-made sandstone aggregate is more researched in railway cast-in-place concrete. Research results show that the machine-made sand aggregate is feasible to be applied to railway cast-in-place concrete members, but the research on the shrinkage of railway machine-made sand aggregate cast-in-place concrete is very little. In recent years, the performance of the machine-made sandstone aggregate cast-in-place concrete for railways is systematically researched by iron institute Li-chemical construction and the like, and the machine-made sandstone aggregate cast-in-place concrete structure comprises a cast-in-place pile, a pier bearing platform, a tunnel lining and the like, but a mixing proportion design method of the machine-made sandstone aggregate cast-in-place concrete based on shrinkage control is not provided. Chinese patent CN 109369097A, a low shrinkage, anti-cracking and high performance mass concrete, Chinese patent CN 102701654B, a class of low shrinkage concrete, Chinese patent CN 103011727B, a low shrinkage concrete and Chinese patent CN 105461274B, a low shrinkage concrete disclose low shrinkage concrete formulations, but the patents lack theoretical support and guidance, lack consideration on shrinkage matching of different components of concrete and lack research on shrinkage of machine-made sand concrete.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and invents a machine-made sand aggregate cast-in-place concrete mix proportion design method based on shrinkage control.
The purpose of the invention can be realized by the following technical scheme: a machine-made sandstone aggregate cast-in-place concrete mix proportion design method based on shrinkage control is characterized by comprising the following steps: 1) determining low shrinkage as a main design target according to the characteristics of the machine-made sandstone aggregate cast-in-place concrete; 2) establishing the relation between the concrete shrinkage and aggregate, an interface and slurry based on a prediction model of the concrete shrinkage and the elastic modulus; 3) the material selection principle and the optimization technology of the raw materials for the low-shrinkage concrete are defined.
The method comprises the following steps of 1), removing a mould after the machine-made sand stone aggregate cast-in-place concrete is molded for 1d, and testing the shrinkage value during 360d maintenance, wherein the I grade is the grade with the shrinkage less than 350 × 10-6，
Grade shrinkage between 350 × 10-6~450×10-6，
In the order of shrinkage greater than 450 × 10-6。
Preferably, the low shrinkage rating is class I.
Establishing a shrinkage prediction model mainly based on the elastic modulus of the concrete, a concrete elastic modulus prediction model based on the elastic modulus of the aggregate and the slurry and a slurry elastic modulus prediction model based on the compressive strength of the slurry in the step 2) according to the relationship between the shrinkage of the concrete and the aggregate, the interface and the slurry.
Preferably, the calculation formula of the shrinkage prediction model based on the elastic modulus of the concrete in the step 2) is as follows:
sh（t, t0）=-khS(t)s∞607Et/(t0+τsh) （1）
in the formulash（t, t0) Shrinkage of concrete structure at age t, t being concrete shrinkage test age, t0To begin the drying age, khAs an environmental correction factor, EtIs the elastic modulus of the concrete at the t-age,s∞and τshIs a coefficient related to the concrete thickness, axial compressive strength, shape and water content.
Preferably, the calculation formula of the concrete elastic modulus prediction model based on the aggregate and slurry elastic modulus in the step 2) is as follows:
Et=EmVm+EgVg（2）
in the formula Em、EgModulus of elasticity, V, of the slurry and aggregate, respectivelym、VgVolume fractions of slurry and aggregate, respectively, and Vm+Vg=1。
Preferably, the calculation formula of the slurry elastic modulus prediction model based on the compressive strength of the slurry in the step 3) is as follows:
Em=4.0279σs 0.1794（3）
in the formula sigmasThe compressive strength of the slurry is obtained.
The vertical type (1) to (3) can be obtained,
sh（t, t0）=-khS(t)s∞607 (4.0279σs 0.1794Vm+EgVg)/(t0+τsh) （4）
the calculation formula (4) establishes the relationship between concrete shrinkage and aggregate, interface and slurry.
The material selection principle and the optimization technology of the raw materials for the low-shrinkage concrete in the step 3) mainly aim at aggregate, interface and slurry.
Preferably, the principle of selecting the aggregate in the step 3) is to select coarse aggregate with moderate elastic modulus and grain size, good grain shape and grading, and select machine-made sand with good grain shape and grading, low MB value and moderate stone powder content.
Preferably, the moderate elastic modulus is 50 GPa-100 GPa, the uniaxial compressive strength is 60 MPa-100 MPa, and the coarse aggregate is mainly selected from one of slant granite, granite speckled, granite flaky granite, quartz sandstone, orthobaric rock, granite, andesite and limestone.
Further preferably, the machine-made sandstone aggregate is 0 mm-20 mm continuous gradation, and the fineness modulus is 4.6-6.0.
More preferably, the coarse aggregate is preferably in a granular form in which the circularity 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.
More preferably, the machine-made sand has a particle shape with a circularity of greater than 0.85 and an aspect ratio of less than 1.5.
Further preferably, the machine-made sand is graded as sand in the zone II.
Further preferably, the machine-made sand has an MB value of less than 1.4 and a stone powder content of less than 10%.
Preferably, the interface optimization technology in step 3) is to reduce the thickness of the interface transition region and reduce the porosity of the interface transition region.
Further preferably, the thickness and porosity of the interface transition zone are reduced mainly by one or more of using a lower water-to-gel ratio, incorporating a water reducing agent and incorporating a large amount of silicon-based materials.
More preferably, the lower water-to-glue ratio is between 0.35 and 0.45.
More preferably, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.
More preferably, the silica-based material is one or more of fly ash, silica fume, rice hull ash, slag powder and metakaolin.
Preferably, the material selection principle of the slurry in the step 3) is to blend mineral admixtures which obviously 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.
Further preferably, the mineral admixture which is doped to remarkably improve the elasticity modulus of the slurry is a calcium-silicon ratio and ultrafine mineral admixture which can improve the calcium-silicon ratio in the cement slurry.
More preferably, the mineral admixture which is added to increase the calcium-silicon ratio of the cement paste is calcium carbonate powder.
More preferably, the superfine mineral admixture is mainly one or more of nano silicon dioxide and ground stone powder.
Further preferably, the gas content of the slurry is increased to control the gas content of the concrete to be less than 4%;
more preferably, the gas content of the slurry can be increased by using an air entraining agent.
Further preferably, the volume fraction of the slurry is 25-35%.
The shrinkage control mechanism-based sandstone aggregate cast-in-place concrete is composed of the same lithologic aggregate and stone powder admixture, and is supplemented with a cementing material, water, an additive and the like, and is prepared from the following components in parts by weight:
cement 100 with a strength grade >42.5 grade,
specific surface area of not less than 400m210-20 kg of ground stone powder,
10-55 parts of mineral admixture,
0 mm-20 mm continuous graded mixed machine-made sand aggregate 376 and 416,
0.4 to 1.0 percent of polycarboxylic acid high-efficiency water reducing agent,
0.01 to 0.05 percent of air entraining agent,
and 42-85.5 of water.
Adding a cementing material and machine-made sandstone aggregate into a stirrer in proportion, forcibly stirring for 60s, adding 3/4 water and an additive into the obtained mixture, forcibly stirring for 60s, then adding 1/4 water and the additive into the obtained mixture, and forcibly stirring for 60 s-180 s to obtain the concrete mixture.
Compared with the prior art, the invention has the following advantages: (1) the quantitative design of the low shrinkage of the mechanical sand aggregate. The shrinkage research on the machine-made sand aggregate cast-in-place concrete is less in the earlier invention, and the concrete prepared by the disclosed invention patent is still high in shrinkage, so that the design target of the low-shrinkage-grade machine-made sand aggregate cast-in-place concrete cannot be met. The low-shrinkage mechanism sandstone aggregate cast-in-place concrete is quantitatively designed based on the technologies of theoretical design, material optimization, optimization and the like. (2) The material selection principle is reasonable and reliable. On the basis of preferentially designing the low-shrinkage mechanism sandstone aggregate cast-in-place concrete, the shrinkage difference value among different components of the concrete is considered at the same time, which is not considered by other invention patents and is also an important characteristic for influencing the cracking of the concrete. The invention reduces the difference of elastic modulus and thermodynamic property of different components by optimizing raw materials. (3) The design method of the mix proportion is advanced. The design concept of the mixing proportion is that the same lithologic sandstone aggregate and stone powder admixture are supplemented with cementing materials, water, additives and the like, the mineral admixture is preferably selected from powder modification, the key index requirement of machine-made sand and the key index control of coarse aggregate, and the design of the mixing proportion of the machine-made sandstone aggregate cast-in-place concrete is provided through different components and different scales based on related theoretical support, so that the method has extremely high advancement.
A shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method is based on the following principle:
a shrinkage control-based machine-made sand aggregate cast-in-place concrete mix proportion design method aims to match elastic moduli of different components on the basis of meeting the overall low shrinkage design target of concrete, and establishes a prediction model of the shrinkage of the machine-made sand aggregate cast-in-place concrete and the correlation of aggregate, interface and slurry according to the following formula:
sh（t, t0）=-khS(t)s∞607 (4.0279σs 0.1794Vm+EgVg)/(t0+τsh)
in the formulash（t, t0) Shrinkage of concrete structure at age t, t being concrete shrinkage test age, t0To begin the drying age, khAs an environmental correction factor, EtIs the elastic modulus of the concrete at the t-age,s∞and τshIs a coefficient relating to the concrete thickness, axial compressive strength, shape and water content, Em、EgModulus of elasticity, V, of the slurry and aggregate, respectivelym、VgVolume fractions of slurry and aggregate, respectively, and Vm+Vg=1，σsThe compressive strength of the slurry is obtained.
Based on an optimization theoretical prediction model of concrete low shrinkage, the concrete elastic modulus is divided into three parts, namely aggregate, an interface and slurry, so that the relationship between the concrete shrinkage and raw materials for concrete can be better established.
In concrete, aggregate occupies a large volume fraction and acts as a framework, and the elastic modulus of aggregate is high, so that the elastic modulus of aggregate has a significant influence on the elastic modulus of concrete. When the modulus of elasticity of the coarse aggregate EgThe larger the volume fraction VgThe larger the concrete is, the larger the elastic modulus of the concrete is, and the lower the shrinkage degree of the concrete is; the larger the maximum particle size of the coarse aggregate is, the better the grading is, the larger the volume fraction occupied by the coarse aggregate is, and the elastic modulus of the concrete is further improved. Hair brushIt is not clear that too low shrinkage is sought, and on the basis of obtaining lower shrinkage, the shrinkage of different components is matched as much as possible, so that the modulus of elasticity, the maximum particle size and the volume fraction of the coarse aggregate need to be moderate. For the machine-made sand, the selection of the machine-made sand with good grain shape and gradation, low MB value and moderate stone powder content is beneficial to improving the workability of concrete.
For the interface, which is a key influencing factor for reducing 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. The method is improved by measures of using a lower water-to-gel ratio or doping a silicon-based mineral admixture and the like, and the main mechanism is to reduce the moisture, the porosity, the content of calcium hydroxide and the like in a transition region.
For the slurry, the C-S-H gel and the pores are mainly used, so that the elastic modulus of the C-S-H gel is improved mainly by improving the calcium-silicon ratio in the cement slurry, and the ultrafine stone powder and the mineral admixture are doped to play a role in promoting hydration of crystal nuclei and filling the pores of the cement stone, so that the elastic modulus of the slurry is improved, the volume fraction of the slurry is increased, the excellent workability of concrete is favorably realized, and the cement consumption can be greatly reduced by replacing the mineral material with higher content in the slurry, and the concrete shrinkage is reduced.
According to the raw material selection principle and the optimization technology, the low-shrinkage machine-made sand aggregate cast-in-place concrete can be prepared, and meanwhile, based on the characteristics that the elastic modulus of coarse aggregate is higher, and the elastic modulus of slurry and an interface is lower, the elastic modulus of the interface and the slurry are improved to match the elastic modulus difference between different components in the aspect of matching proportion design, and meanwhile, the elastic modulus of sand powder is matched by using stones, sands and powders with the same lithology.
Drawings
In order to illustrate the embodiments of the invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings described below are only one embodiment of the invention, and that other drawings may be derived from these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a machine-made sandstone aggregate cast-in-place concrete mix proportion design method based on deformation control.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples, which are given by way of illustration only and are not limiting to the scope of the invention.
Example 1: in the raw materials, the cement is P.O42.5 grade, and the consumption of the cement is 270kg/m3The water-to-gel ratio is 0.36, the coarse aggregate is andesite, the machine-made sandstone aggregate is 0 mm-20 mm continuous gradation, the fineness modulus is 5.2, the circularity of the coarse aggregate is 0.81, the needle sheet content is 4%, the fine aggregate is andesite machine-made sand, the gradation is medium sand in a region II, the MB value is 1.2, the stone powder content is 5%, the circularity of the machine-made sand is 0.86, the length-diameter ratio is 1.38, the fly ash is class II fly ash, and the using amount is 90kg/m3The amount of rice hull ash is 70kg/m3The specific surface area of the ground andesite powder is 450m2The dosage of the extract is 30kg/m3The gas content is 3%, and the volume fraction of the slurry is 25%.
Adding a cementing material and machine-made sandstone aggregate into a stirrer in proportion, forcibly stirring for 60s, adding 3/4 water and an additive into the obtained mixture, forcibly stirring for 60s, then adding 1/4 water and the additive into the obtained mixture, and forcibly stirring for 60 s-180 s to obtain the concrete mixture. The concrete size is 100mm multiplied by 400mm, the mould is removed after 1d of casting forming, the concrete is moved into a constant temperature and constant temperature room with the temperature of 20 +/-2 ℃ and the relative humidity of 60 +/-5%, and the drying shrinkage of the concrete is tested for 360 d.
Example 2: in the raw materials, the cement is P.O42.5 grade, and the consumption of the cement is 250kg/m3The water-to-gel ratio is 0.39, the coarse aggregate is inclined long granite, the machine-made sandstone aggregate is 0 mm-20 mm continuous gradation, the fineness modulus is 5.4, the circularity of the coarse aggregate is 0.83, the needle sheet content is 4%, the fine aggregate is inclined long granite machine-made sand, the gradation is medium sand in a zone II, the MB value is 1.0, the stone powder content is 6%, the circularity of the machine-made sand is 0.88, the length-diameter ratio is 1.36, the volume fraction of the aggregate is 80%, and the fly ash is grade II fly ash,the dosage is 80kg/m3The amount of rice hull ash is 60kg/m3The specific surface area of the finely ground slant-long granite powder is 450m2Per kg, in an amount of 25kg/m3The dosage of the nano silicon dioxide is 10kg/m3The gas content is 3.5%, and the volume fraction of the slurry is 30%.
Adding a cementing material and machine-made sandstone aggregate into a stirrer in proportion, forcibly stirring for 60s, adding 3/4 water and an additive into the obtained mixture, forcibly stirring for 60s, then adding 1/4 water and the additive into the obtained mixture, and forcibly stirring for 60 s-180 s to obtain the concrete mixture. The concrete size is 100mm multiplied by 400mm, the mould is removed after 1d of casting forming, the concrete is moved into a constant temperature and constant temperature room with the temperature of 20 +/-2 ℃ and the relative humidity of 60 +/-5%, and the drying shrinkage of the concrete is tested for 360 d.
Example 3: in the raw materials, the cement is P.O42.5 grade, and the consumption of the cement is 210kg/m3The water-cement ratio is 0.39, the coarse aggregate is limestone, the machine-made sandstone aggregate is 0 mm-20 mm continuous gradation, the fineness modulus is 5.5, the circularity of the coarse aggregate is 0.85, the needle sheet content is 4%, the fine aggregate is limestone machine-made sand, the gradation is medium sand in a zone II, the MB value is 0.8, the stone powder content is 7%, the circularity of the machine-made sand is 0.92, the length-diameter ratio is 1.32, and the class I fly ash is 30kg/m3The amount of rice hull ash is 50kg/m3The metakaolin is 50kg/m3The specific surface area of the limestone powder is 400m2The dosage of the extract is 20kg/m3The dosage of the nano silicon dioxide is 10kg/m3The gas content is 3.5%, and the volume fraction of the slurry is 35%.
Adding a cementing material and machine-made sandstone aggregate into a stirrer in proportion, forcibly stirring for 60s, adding 3/4 water and an additive into the obtained mixture, forcibly stirring for 60s, then adding 1/4 water and the additive into the obtained mixture, and forcibly stirring for 60 s-180 s to obtain the concrete mixture. The concrete size is 100mm multiplied by 400mm, the mould is removed after 1d of casting forming, the concrete is moved into a constant temperature and constant temperature room with the temperature of 20 +/-2 ℃ and the relative humidity of 60 +/-5%, and the drying shrinkage of the concrete is tested for 360 d.
The measured performance of the low shrinkage mechanism sandstone aggregate cast-in-place concrete mix proportion design and the contrast mechanism sandstone aggregate cast-in-place concrete mix proportion design provided by the embodiments 1-3 is shown in tables 1 and 2.
TABLE 1 test of the working performance of the machine-made sand aggregate cast-in-place concrete with different proportions
TABLE 2 shrinkage test of machine-made sand aggregate cast-in-place concrete with different proportions
As can be seen from Table 1, the concrete prepared in example 3 has good working properties and completely meets the construction requirements of cast-in-place concrete. As can be seen from Table 2, compared with the machine-made gravel aggregate cast-in-place concrete designed by the comparative mix proportion, the difference of the elastic modulus of different components of the concrete in the embodiments 1 to 3 is relatively small, and further, the different components of the concrete in the groups are relatively uniform in shrinkage, and the internal stress concentration of the concrete is weakened. Further analysis shows that the shrinkage is small, the elastic modulus of each component is closer, the design target of the invention is met, the long-term safe use of the machine-made sandstone aggregate cast-in-place concrete is favorably realized, and the cracking is not easy to occur.
Claims (11)
1. A machine-made sandstone aggregate cast-in-place concrete mix proportion design method based on shrinkage control is characterized by comprising the following steps: 1) determining low shrinkage as a main design target according to the characteristics of the machine-made sandstone aggregate cast-in-place concrete; 2) establishing the relation between the concrete shrinkage and aggregate, an interface and slurry based on a prediction model of the concrete shrinkage and the elastic modulus; 3) the material selection principle and the optimization technology of the raw materials for the low-shrinkage concrete are defined.
2. The shrinkage control-based machine-made gravel aggregate cast-in-place concrete mix proportion design method according to claim 1, wherein the machine-made gravel aggregate in step 1) is in-placeRemoving the mould after pouring concrete and forming for 1d, and testing the shrinkage value during maintenance for 360d, wherein the shrinkage of I grade is less than 350 × 10-6，
A shrinkage of order 350 × 10-6~450×10-6，
In order of shrinkage greater than 450 × 10-6。
3. The method for designing the mix proportion of the mechanical sandstone aggregate cast-in-place concrete based on the shrinkage control as claimed in claim 1, wherein the relationship between the shrinkage of the concrete and the aggregate, the interface and the slurry in the step 2) is established by the combination of a shrinkage prediction model mainly based on the elastic modulus of the concrete, a concrete elastic modulus prediction model based on the elastic modulus of the aggregate and the slurry and a slurry elastic modulus prediction model based on the compressive strength of the slurry.
4. The shrinkage control-based mechanical sand aggregate cast-in-place concrete mix proportion design method according to claim 3, wherein the calculation formula of the shrinkage prediction model based on the concrete elastic modulus in the step 2) is as follows:
sh（t, t0）=-khS(t)s∞607Et/(t0+τsh) （1）
in the formulash（t, t0) Shrinkage of concrete structure at age t, t being concrete shrinkage test age, t0To begin the drying age, khAs an environmental correction factor, EtIs the elastic modulus of the concrete at the t-age,s∞and τshIs a coefficient related to the concrete thickness, the axial compressive strength, the shape and the water content;
the calculation formula of the concrete elastic modulus prediction model based on the aggregate and slurry elastic modulus is as follows:
Et=EmVm+EgVg（2）
in the formula Em、EgModulus of elasticity, V, of the slurry and aggregate, respectivelym、VgVolume fractions of slurry and aggregate, respectively, and Vm+Vg=1；
The calculation formula of the slurry elastic modulus prediction model based on the compressive strength of the slurry is as follows:
Em=4.0279σs 0.1794（3）
in the formula sigmasThe compressive strength of the slurry is;
the vertical type (1) to (3) can be obtained,
sh（t, t0）=-khS(t)s∞607 (4.0279σs 0.1794Vm+EgVg)/(t0+τsh) （4）
the calculation formula (4) establishes the relationship between concrete shrinkage and aggregate, interface and slurry.
5. The shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method according to claim 1, wherein the material selection principle and optimization technology of the raw materials for the low-shrinkage concrete in the step 3) mainly aim at aggregate, interface and slurry.
6. The machine-made sandstone aggregate cast-in-place concrete mix proportion design method based on the shrinkage control as claimed in claim 5, wherein the aggregate selection principle in the step 3) is to select coarse aggregate with moderate elastic modulus and good grain size, grain shape and grading, and select machine-made sand with good grain shape and grading, low MB value and moderate stone powder content; the interface optimization technology is to reduce the thickness of the interface transition region and reduce the porosity of the interface transition region; the material selection principle of the slurry is to mix mineral admixture which obviously improves 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.
7. The shrinkage control-based machine-made gravel aggregate cast-in-place concrete mix proportion design method according to claim 6, wherein the material selection principle of the machine-made gravel aggregate in the step 3) has the following specific indexes: the machine-made sandstone aggregate has a mother rock elastic modulus of 50-100 GPa, a uniaxial compressive strength of 60-100 MPa, the mother rock is mainly one of long inclined granite, speckled granite, twisted granite, quartz sandstone, long rock, granite, andesite and limestone, and is 0-20mm continuous gradation, and the fineness modulus of the machine-made sandstone aggregate is 4.6-6.0; the particle shape of the coarse aggregate is preferably that the circularity of the coarse aggregate is more than 0.8, and the needle sheet content is less than 5 percent of the total mass of the coarse aggregate; the particle shape of the machine-made sand is preferably that the circularity is more than 0.85, the length-diameter ratio is less than 1.5, the machine-made sand grading is sand in a zone II, the MB value of the machine-made sand is less than 1.4, and the content of the stone powder is less than 10%.
8. The shrinkage control-based machine-made sand aggregate cast-in-place concrete mix proportion design method according to claim 6, wherein the interface optimization technology in the step 3) is to reduce the thickness and porosity of an interface transition zone, and the specific optimization technology is as follows: mainly by using one or more of materials with the water-to-glue ratio of 0.35-0.45, and adding a polycarboxylic acid high-efficiency water reducing agent and adding fly ash, silica fume, rice hull ash, slag powder and metakaolin.
9. The shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method as claimed in claim 6, wherein the material selection principle and optimization technology of the slurry in step 3) is to mix mineral admixtures which can significantly improve the elastic modulus of the slurry and reduce the gas content of the slurry, and the specific material selection principle and optimization technology are as follows: one or more of calcium carbonate powder, nano silicon dioxide and ground stone powder are doped, the gas content of the slurry can be increased by using an air entraining agent, the gas content is controlled to be less than 4%, and the volume fraction of the slurry is 25% -35%.
10. The shrinkage control-based machine-made sandstone aggregate cast-in-place concrete mix proportion design method according to claim 1, wherein the shrinkage control-based sandstone aggregate cast-in-place concrete is prepared from the same lithologic sandstone aggregate and stone powder admixture, as well as a cementing material, water, an additive and the like, and comprises the following components in parts by weight:
cement 100 with a strength grade >42.5 grade,
specific surface area of not less than 400m210-20 kg of ground stone powder,
10-70 parts of mineral admixture,
0-20mm continuous graded mixing mechanism sand aggregate 376-416,
0.4 to 1.0 percent of polycarboxylic acid high-efficiency water reducing agent,
0.01 to 0.05 percent of air entraining agent,
and 42-85.5 of water.
11. The method for designing the mixing proportion of the machine-made sandstone aggregate cast-in-place concrete based on the shrinkage control as claimed in claim 1, wherein the preparation method comprises the steps of adding a cementing material and the machine-made sandstone aggregate into a stirrer in proportion, forcibly stirring for 60s, adding 3/4 water and an additive into the obtained mixture, forcibly stirring for 60s, then adding 1/4 water and the additive into the obtained mixture, and forcibly stirring for 1min to 3min to obtain the concrete mixture.
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