CN113880494B - Super-hydrophobic water-based emulsion for cement-based materials and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of cement concrete anticorrosion, and specifically discloses a super-hydrophobic water-based emulsion for cement-based materials, a preparation method and application thereof. The emulsion includes an aqueous phase and modified microparticles dispersed therein. Wherein: the modified particle is a core-shell structure formed by modifying inorganic nanoparticles wrapped on the surface of hydrophobic substances, and the modified inorganic nanoparticles are two-layered structures formed by lipophilic substances bonded to the surface of hydrophilic inorganic nanoparticles. Affinity particles. In the present invention, the core-shell structure formed by the modified inorganic nanoparticles wrapped on the surface of the hydrophobic substance is used as the effective component of the emulsion (i.e. modified particles). After the emulsion is added to the concrete, the modified particles pass through the polar groups on the surface Through physical or weak chemical adsorption on the surface of cement particles, the cement is completely hydrated. After a certain age, the hydrophobic substances are released to build a hydrophobic network structure, and finally the cement concrete has both mechanical strength and super-hydrophobic properties.

Description

Superhydrophobic water-based emulsion for cement-based materials and its preparation method and application

technical field

The invention relates to the technical field of cement concrete anticorrosion, in particular to a super-hydrophobic water-based emulsion for cement-based materials and a preparation method and application thereof.

Background technique

Seawater is rich in chloride ions, magnesium ions and sulfate ions, and these ions will enter the concrete with the seawater and cause corrosion to the concrete. Seawater is saturated with oxygen under the action of mechanical agitation and strong natural convection on the sea surface, so ordinary steel materials are severely corroded in the ocean. Although inspired by the lotus leaf effect, there has been a technology to improve the durability of concrete through hydrophobic anticorrosion (the principle is to prevent chloride ions, magnesium ions and sulfate ions from entering concrete by reducing water permeability). However, if only imitating the superhydrophobic surface of the lotus leaf, applying a superhydrophobic coating on the concrete surface will cause problems such as cracking of the surface hydrophobic layer, aging of the coating, peeling of the coating, weak mechanical properties, etc., and it is difficult to achieve true hydrophobic anticorrosion.

In order to solve this problem, volumetric hydrophobic concrete was born. However, the existing hydrophobic concrete is difficult to achieve both strength and hydrophobicity. The active agent will restrict the entry of water in the concrete system, so that the cement cannot be fully hydrated, thereby reducing the mechanical strength of the cement-based material. In addition, the hydrophobic emulsion will form defects during the cement hydration process of the cement-based material, resulting in a decrease in the mechanical strength of the cement-based material; at the same time, the release of hydrophobic substances in the existing hydrophobic emulsion is too fast, which will lead to incomplete cement hydration of the cement-based material. Therefore, the mechanical strength is generally low. In short, due to the reduction of strength by hydrophobic emulsion surfactants, the super-hydrophobic performance and high-strength performance of cement-based materials are always at the expense of the other.

Contents of the invention

In view of the above problems, the present invention provides a super-hydrophobic aqueous emulsion for cement-based materials and its preparation method and application. The technical solution of the present invention focuses on the modification of the hydrophobic emulsion and the innovation of the cement anti-corrosion system. The slow-release body formed by the modified inorganic nanoparticles and the hydrophobic substance effectively overcomes the incompatibility between the hydrophobic emulsion and the cement particles and causes the cement water problem of obstruction. To achieve the above object, the present invention has the following technical solutions.

In the first aspect of the present invention, there is provided a superhydrophobic aqueous emulsion for cement-based materials, the emulsion includes an aqueous phase and modified particles dispersed therein. Wherein: the modified particles are a core-shell structure formed by wrapping modified inorganic nanoparticles on the surface of hydrophobic substances, and the modified inorganic nanoparticles are two-layered structures formed by bonding lipophilic substances to the surface of hydrophilic inorganic nanoparticles. Affinity particles.

Further, the hydrophobic substance includes: at least one of fluorosilanes, siloxanes and the like.

Optionally, the fluorosilanes include any one of tridecafluorooctyltriethoxysilane, heptadecafluorodecyltriethoxysilane, etc., and the siloxanes include polydimethyl Any one of base siloxane, n-octyltriethoxysilane, isobutyltriethoxysilane, etc. In the present invention, the superhydrophobic performance is given to the cement concrete after the hydrophobic substance is released later, thereby preventing chloride ions, magnesium ions and sulfate ions in seawater from entering the concrete.

Further, the hydrophilic inorganic nanoparticles include: at least one of nano-silicon dioxide, nano-titanium dioxide, nano-bentonite, nano-diatomaceous earth and the like. Such inorganic nanoparticles are hydrophilic, and after the emulsion of the present invention is added to cement concrete, the hydrophilic inorganic nanoparticles can prevent the release of hydrophobic substances in the cement in the early stage of hydration, and prevent the hydrophobic substances from affecting the hydration of cement.

Further, the particle size of the hydrophilic inorganic nanoparticles is preferably controlled between 20-90nm.

Further, the lipophilic substance is selected from silanes, etc. Optionally, the silanes include hexamethyldisilazane (HMDS), γ-aminopropyltriethoxysilane, γ-form Any one of acryloyloxypropyltrimethoxysilane and the like. This kind of lipophilic substance can bond with the above-mentioned functional groups on the surface of the inorganic nanoparticles and then attach to the surface of the inorganic nanoparticles, so that the inorganic nanoparticles are both hydrophobic and hydrophilic, that is, amphiphilic. The amphiphilicity of inorganic nanoparticles, that is, the wettability of inorganic nanoparticles, is a key factor determining the stability of the emulsion, because it determines the adsorption energy of inorganic nanoparticles at the oil-water interface, and the inorganic nanoparticles have a strong effect on the water phase and the water phase. The wetting effect of the oil phase is equivalent, and the adsorption energy at the water-oil interface reaches the maximum at this time, and the better the stability of the emulsion (that is, the oil phase can be wrapped by using inorganic nanoparticles). At the same time, because the inorganic nanoparticles have amphiphilicity, they can be bonded to the cement through the hydrophilic end in the concrete system (through the formation of hydrogen bonds between hydroxyl groups).

In a second aspect of the present invention, the preparation method for the super-hydrophobic water-based emulsion for cement-based materials is provided, comprising the steps of:

(1) Disperse the hydrophilic inorganic nanoparticles in ethanol to form a dispersion liquid, and set aside.

(2) After heating the dispersion liquid, add the lipophilic substance, and then keep warm for the reaction. After the end, the solid product is separated, washed and dried to obtain the modified inorganic nanoparticles, which are ready for use.

(3) Dispersing the modified inorganic nanoparticles in water, then adding the hydrophobic substance and mechanically stirring at a high speed to obtain a super-hydrophobic water-based emulsion.

Further, in the preparation method, the mass ratio of hydrophilic inorganic nanoparticles, lipophilic substances, hydrophobic substances, and water is 0.2-2.0:0.2-2.0:10.0-50.0:50.0-90.0.

Further, in step (1), the ratio of the hydrophilic inorganic nanoparticles to ethanol is 1g:50ml, and after mixing the inorganic nanoparticles with ethanol, ultrasonically disperses into a dispersion liquid, which is convenient for the later stage of the inorganic nanoparticles. Modified to make its surface bonded with lipophilic substances to become amphiphilic nanoparticles.

Further, in step (2), the heating temperature is 60-70°C, and the heat preservation reaction time is 5-12h. Under heating conditions, it helps to increase the activity of the reactive group. The lipophilic substance contains a hydrophobic/lipophilic functional group, and when the lipophilic substance is connected to the surface of the hydrophilic inorganic nanoparticle through a reaction, the hydrophilic inorganic nanoparticle becomes a substance carrying a hydrophobic/lipophilic functional group, and then In addition to the hydrophilicity of the inorganic nanoparticles themselves, the obtained modified inorganic nanoparticles have both hydrophilicity and lipophilicity.

Further, in step (2), the solid product is separated from the reaction liquid by means of centrifugation or filtration, then the solid product is washed with water, and then dried at a temperature range of 65-120°C to obtain the modified inorganic Nanoparticles.

Further, in step (3), ultrasonically disperse the modified inorganic nanoparticles in water again, add the hydrophobic substance and then perform magnetic stirring first, then carry out high-speed shear stirring, and add a defoamer after completion to continue stirring, that is superhydrophobic emulsion. In this step, the modified inorganic nanoparticles are wrapped on the surface of the hydrophobic substance by adsorption, preventing the release of the hydrophobic substance therein at the initial stage of cement hydration, and preventing the hydrophobic substance from affecting the cement hydration. In addition, because inorganic nanoparticles are rich in silicon, aluminum, and calcium elements, their role in cement can promote cement hydration, dense pore structure,

In the third aspect of the present invention, the application of the superhydrophobic water-based emulsion for cement-based materials in construction engineering and other fields is provided. It is preferably used in cement concrete. Preferably, the mass fraction of the super-hydrophobic emulsion in cement concrete is 0.5-3%.

Compared with the prior art, the present invention has the following beneficial effects:

(1) In the present invention, the core-shell structure formed by wrapping the modified inorganic nanoparticles on the surface of the hydrophobic substance is the effective component of the emulsion (i.e. modified particles). After the emulsion is added to concrete, the modified particles pass through the poles on the surface. The active groups are physically or weakly chemically adsorbed on the surface of cement particles, so that the cement is completely hydrated. After a predetermined age, the hydrophobic substances are released to build a hydrophobic network structure. The reason why the above effects can be achieved is that in the early stage of hydration, the water in the cement concrete system will first react with the modified inorganic nanoparticles on the outside, which is equivalent to the protection of the internal hydrophobic substances, thus preventing the hydrophobic substances in the cement Released at the initial stage of hydration, the cement hydration process can be fully carried out to ensure the strength of concrete. With the continuous reaction and consumption of the modified inorganic nanoparticles, the internal hydrophobic substances are gradually exposed and released. At this time, the hydration process of the cement has been fully carried out, the cement hydration network is well established, and the release of the hydrophobic substances no longer affects the strength of the concrete. At the same time, the released hydrophobic substances begin to build a hydrophobic network structure, and finally make the cement concrete have both mechanical strength and super-hydrophobic properties.

(2) In the present invention, the core-shell modified particles formed by wrapping modified inorganic nanoparticles on the surface of hydrophobic substances also have the effect of making up for the decline in concrete strength caused by hydrophobic substances. The reason is that in the emulsion, the modified inorganic nanoparticles Also as a substance to stabilize the emulsion, it can improve the dispersibility of the emulsion.

(3) The super-hydrophobic water-based emulsion of the present invention not only significantly reduces the excessively high emulsifier dosage in the preparation process of the original hydrophobic emulsion, saves costs, but is also non-toxic and harmless to the human body, and is environmentally friendly. In addition, the invented super-hydrophobic water-based emulsion The emulsion is a transparent emulsion, which basically does not change the appearance and color of the cement concrete after being added to the cement concrete.

Description of drawings

Fig. 1 is the rendering and microscopic view of the superhydrophobic aqueous emulsion prepared in the following first embodiment.

Fig. 2 is the effect diagram of cement concrete surface wettability test in the following examples.

Fig. 3 is a schematic diagram of the action mechanism of the superhydrophobic aqueous emulsion in the following examples.

Detailed ways

The present invention is further described below in conjunction with specific examples, and these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention, and the preferred implementation method and material described in the text are only used for demonstration, below in conjunction with specific implementation mode to this invention Detailed description of the invention.

first embodiment

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh silicon dioxide powder (particle size 20-90nm), HMDS, polydimethylsiloxane, water in sequence according to the weight ratio of 1.5:1.5:30:65, set aside.

(2) Add the silicon dioxide powder in step (1) into ethanol, the ratio of the silicon dioxide powder to ethanol is 1g:50ml, and ultrasonicate for 15min to form a dispersion liquid, which is ready for use.

(3) Stir the dispersion in step (2) in a water bath at a temperature of 60°C for 15 minutes, then heat it in a water bath to 65°C, add HMDS, and then keep it warm for 8 hours. After completion, add the obtained reaction to the centrifuge After centrifugation, the separated solid product was washed with water, and then vacuum-dried at 105° C. to obtain modified silica particles for future use.

(4) Add the modified silicon dioxide nanoparticles in the step (3) into the water for ultrasonication for 15min, then add the polydimethylsiloxane and then magnetically stir for 20min, and then stir in a high-speed shear (10000r /min) and stirred for 10 minutes, and finally added defoamer and magnetically stirred for 2 minutes to obtain a super-hydrophobic water-based emulsion, as shown in Figure 1.

second embodiment

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh nano diatomite powder, γ-aminopropyltriethoxysilane (KH550), tridecafluorooctyltriethoxysilane and water in sequence according to the weight ratio of 2.0:2.0:50:90, spare.

(2) Add the nano-diatomite powder in step (1) into ethanol, the ratio of the nano-diatomite powder to ethanol is 1g:50ml, and ultrasonicate for 15min to form a dispersion liquid, which is ready for use.

(3) Stir the dispersion in step (2) in a water bath at a temperature of 60°C for 15 minutes, then heat it in a water bath to 70°C, add KH550, and then keep it warm for 5 hours. After completion, add the obtained reaction to the centrifuge After centrifugation, the separated solid product is washed with water, and then vacuum-dried at 120° C. to obtain modified nano-diatomite particles for future use.

(4) Add the modified nano-diatomite nanoparticles in the step (3) into the water for ultrasonication for 15min, then add tridecafluorooctyltriethoxysilane and then magnetically stir for 20min, and then stir in the high-speed shearing machine (10000r/min) under stirring for 10min, and finally add antifoaming agent and magnetically stir for 2min to obtain a super-hydrophobic water-based emulsion.

third embodiment

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh nano-bentonite powder, γ-methacryloxypropyltrimethoxysilane (KH570), heptadecafluorodecyltriethoxysilane, water, set aside.

(2) Add the nano-bentonite powder in step (1) into ethanol, the ratio of the nano-bentonite powder to ethanol is 1g:50ml, and ultrasonicate for 15min to form a dispersion liquid for later use.

(3) Stir the dispersion in step (2) in a water bath at a temperature of 60°C for 15 minutes, then keep the water bath at 60°C and add KH570 to keep it warm for 12 hours. After completion, add the obtained reaction to a centrifuge for centrifugation , washing the separated solid product with clean water, and then vacuum-drying at a temperature of 65°C to obtain modified nano-bentonite particles for future use.

(4) Add the modified nano-bentonite nanoparticles in the step (3) into the water for ultrasonication for 15min, then add heptadecafluorodecyltriethoxysilanes and then magnetically stir for 20min, then in a high-speed shear ( Stir at 10000r/min) for 10min, and finally add defoamer and magnetically stir for 2min to obtain a super-hydrophobic water-based emulsion.

Fourth embodiment

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh nano-titanium dioxide powder, HMDS, isobutyltriethoxysilane, and water sequentially according to the weight ratio of 0.2:0.2:10:55, and set aside.

(2) Add the nano-titanium dioxide powder in step (1) into ethanol, the ratio of the nano-titanium dioxide powder to ethanol is 1g:50ml, and ultrasonicate for 15 minutes to form a dispersion liquid for later use.

(3) Stir the dispersion in step (2) in a water bath at a temperature of 60°C for 15 minutes, then heat it in a water bath to 65°C, add HMDS, and keep it warm for 10 hours. After completion, add the obtained reaction to the centrifuge After centrifugation, the separated solid product is washed with water, and then vacuum-dried at a temperature of 90° C. to obtain modified nano-titanium dioxide particles, which are ready for use.

(4) Add the modified nano-titanium dioxide nanoparticles in the step (3) into the water for ultrasonic 15min, then add isobutyltriethoxysilane and then magnetically stir for 20min, then in a high-speed shear (10000r/min ) under stirring for 10 minutes, and finally adding a defoamer and magnetically stirring for 2 minutes to obtain a super-hydrophobic water-based emulsion.

The first test example

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh silicon dioxide powder (particle size 20-90nm), polydimethylsiloxane, and water in sequence according to the weight ratio of 1.5:30:65, and set aside.

(2) Add the silicon dioxide powder in step (1) into the water and sonicate for 15 minutes, then add polydimethylsiloxane and stir magnetically for 20 minutes, then stir for 10 minutes under a high-speed shear (10000r/min) , and finally add defoamer and magnetically stir for 2 minutes to obtain a super-hydrophobic water-based emulsion.

The second test example

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh nanometer diatomite powder, tridecafluorooctyltriethoxysilane and water sequentially according to the weight ratio of 2.0:50:90, and set aside.

(2) Add the nanometer diatomaceous earth nanoparticles in the step (1) into the water for ultrasonication for 15min, then add tridecafluorooctyltriethoxysilane and then magnetically stir for 20min, and then stir in a high-speed shearing machine (10000r /min) and stirred for 10 minutes, and finally added defoamer and magnetically stirred for 2 minutes to obtain a super-hydrophobic water-based emulsion.

The third test example

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh the nano-bentonite powder, heptadecafluorodecyltriethoxysilane and water sequentially according to the weight ratio of 1.5:30:50, and set aside.

(2) Add the nano-bentonite nanoparticles in the step (1) into water for ultrasonication for 15 minutes, then add heptadecafluorodecyltriethoxysilane and then magnetically stir for 20 minutes, then place the mixture under high-speed shearing machine (10000r/min) Stir for 10 minutes, and finally add defoamer and magnetically stir for 2 minutes to obtain a super-hydrophobic water-based emulsion.

Fourth test example

A kind of preparation method for the superhydrophobic aqueous emulsion of cement-based material, comprises the steps:

(1) Weigh silicon dioxide powder (particle size 20-90nm), HMDS, polydimethylsiloxane, water in sequence according to the weight ratio of 1.5:1.5:30:65, set aside.

(2) Add the silicon dioxide powder and HMDS in the step (1) into water for ultrasonication for 15 minutes, then add polydimethylsiloxane and stir magnetically for 20 minutes, then stir under a high-speed shear (10000r/min) After 10 minutes, finally add defoamer and magnetically stir for 2 minutes to obtain a super-hydrophobic water-based emulsion.

Take the super-hydrophobic water-based emulsion prepared in the above-mentioned embodiments and test examples, mix it with cement mortar and make a test block, test its mechanical properties, water absorption rate, and the results of electrochemical corrosion performance are shown in the following table.

Table 1

category 28d compressive strength 240h water absorption Corrosion potential first embodiment 40.1MPa 4.3% -81mV The first test example 31.6 MPa 6.16% -91.2mV performance improvement 26.9% 43.25% 12.59%

As shown in Table 1, the first test example lacks the modification of inorganic nanoparticle silica, and silica does not possess good amphiphilicity, so that it does not have sufficient adsorption energy at the oil-water interface, and the emulsion is in an unstable state. Silica cannot effectively wrap hydrophobic substances, resulting in a significant decrease in the strength of the cement-based test block. In addition, the water absorption rate and corrosion potential of the cement-based test block in this example are also significantly reduced, indicating that the hydrophobicity and corrosion resistance of the cement-based test block have been effectively improved at the same time.

Table 2

category 28d compressive strength 240h water absorption Corrosion potential second embodiment 40.4MPa 4.47% -84.5mV The second test example 30.7MPa 5.6% -92.2mV performance increase 31.6% 25.28% 9.11%

As shown in Table 2, the second test example lacks the modification of inorganic nanoparticle diatomite, and diatomite does not have certain amphiphilicity, so that it does not have sufficient adsorption energy at the oil-water interface, and the emulsion is in an unfavorable state. In a stable state, diatomite cannot wrap hydrophobic substances well, resulting in a significant decrease in the strength of the cement-based test block. In addition, the water absorption rate and corrosion potential of the cement-based test block in this example are also significantly reduced, indicating that the hydrophobicity and corrosion resistance of the cement-based test block have been effectively improved at the same time.

table 3

category 28d compressive strength 240h water absorption Corrosion potential third embodiment 42.6MPa 5.33% -91.5mV The third test example 31.9MPa 7.02% -102.7mV performance improvement 33.5% 31.70% 12.24%

As shown in Table 3, the third test example lacks the modification of inorganic nano-particle bentonite, and bentonite does not have certain amphiphilicity, so that it does not have sufficient adsorption energy at the oil-water interface, and the emulsion is in an unstable state. Bentonite cannot wrap hydrophobic substances well, resulting in a significant decrease in the strength of cement-based test blocks. In addition, the water absorption rate and corrosion potential of the cement-based test block in this example are also significantly reduced, indicating that the hydrophobicity and corrosion resistance of the cement-based test block have been effectively improved at the same time.

Table 4

category 28d compressive strength 240h water absorption Corrosion potential first embodiment 40.1MPa 4.3% -81mV Fourth test example 27.4 MPa 6.11% -92.7mV performance improvement 46.4% 42.09% 14.44%

As shown in Table 4, in the fourth test example, ultrasonication of inorganic nanoparticle silica and modifier HMDS did not change the original hydrophilicity of silica. On the contrary, due to the presence of HMDS in the emulsion, the emulsion The steady state is even worse, and the mechanical strength of the cement-based test block deteriorates significantly. In addition, the water absorption rate and corrosion potential of the cement-based test block in this example are also significantly reduced, indicating that the hydrophobicity and corrosion resistance of the cement-based test block have been effectively improved at the same time.

Figure 1 from left to right shows the emulsions prepared by the first embodiment, the second embodiment, the fourth embodiment, the first test example and the fourth test example respectively. By comparison, it is found that oil-water layering occurs in the test example, and the stability of the emulsion is poor. , while the emulsion stability of the examples is good. At the same time, the optical microscope image of the hydrophobic emulsion of the fourth embodiment is shown, the particle size is about 8 μm, and the dispersion performance is good.

Figure 2 shows that after the hydrophobic emulsion prepared in the first embodiment is mixed with cement mortar, the macroscopic hydrophobic performance of the mortar is improved, and the water contact angle of the modified mortar section reaches 134.51°, indicating that it has excellent superhydrophobic performance.

Figure 3 shows an explanatory diagram of the action mechanism of the hydrophobic emulsion mixed with mortar in the embodiment of the present invention. After the emulsion is added to the concrete, the modified silicon dioxide, etc., can pass through the polar groups on its surface through physical or weak chemical methods. Adsorbed on the surface of cement particles, the cement is completely hydrated. After a certain age, the hydrophobic substances are released to build a hydrophobic network structure, and finally the cement concrete has both mechanical strength and super-hydrophobic properties.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still understand the foregoing embodiments The recorded technical solutions are modified, or some of the technical features are equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. Superhydrophobic aqueous emulsion for cement-based materials, characterized in that the emulsion includes a water phase and modified particles dispersed therein; wherein: the modified particles are formed by wrapping modified inorganic nanoparticles on the surface of a hydrophobic substance core-shell structure; the modified inorganic nanoparticles are amphiphilic particles formed by bonding lipophilic substances on the surface of hydrophilic inorganic nanoparticles, and the inorganic nanoparticles are rich in silicon, aluminum, and calcium elements; The hydrophobic substance includes at least one of fluorosilanes and siloxanes; the fluorosilanes include any of tridecafluorooctyltriethoxysilane and heptadecafluorodecyltriethoxysilane One; the siloxanes include any one of polydimethylsiloxane, n-octyltriethoxysilane, and isobutyltriethoxysilane; The hydrophilic inorganic nanoparticles include: at least one of nano-silicon dioxide, nano-titanium dioxide, nano-bentonite, and nano-diatomite; The lipophilic substance is selected from silanes, and the silanes include hexamethyldisilazane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane any of the The preparation method of the described super-hydrophobic aqueous emulsion for cement-based materials comprises the steps: (1) Dispersing the hydrophilic inorganic nanoparticles in ethanol to form a dispersion liquid for later use; (2) Add the lipophilic substance after heating the dispersion, and then keep warm for the reaction. After the end, the solid product is separated, washed and dried to obtain the modified inorganic nanoparticles, and set aside; (3) Dispersing the modified inorganic nanoparticles in water, then adding the hydrophobic substance and mechanically stirring at high speed to obtain a super-hydrophobic water-based emulsion; In the preparation method, the mass ratio of hydrophilic inorganic nanoparticles, lipophilic substances, hydrophobic substances, and water is 0.2-2.0:0.2-2.0:10.0-50.0:50.0-90.0. 2. the superhydrophobic aqueous emulsion for cement-based materials according to claim 1, characterized in that, the particle diameter of the hydrophilic inorganic nanoparticles is controlled between 20 ~ 90nm. 3. The superhydrophobic water-based emulsion for cement-based materials according to claim 1, characterized in that, in step (1), the ratio of the hydrophilic inorganic nanoparticles to ethanol is 1g:50ml. 4. The superhydrophobic water-based emulsion for cement-based materials according to claim 1, characterized in that, in step (2), the heating temperature is 60-70°C, and the heat preservation reaction time is 5-12h. 5. The superhydrophobic water-based emulsion for cement-based materials according to claim 1, characterized in that in step (2), the solid product is separated from the reaction solution by centrifugation or filtration, and then the solid product is washed with water The solid product is then dried at a temperature range of 65-120° C. to obtain modified inorganic nanoparticles. 6. The superhydrophobic water-based emulsion for cement-based materials according to any one of claims 1-5, characterized in that, in step (3), after adding the hydrophobic substance, magnetic stirring is first performed, and then shear stirring is performed, After completion, add defoamer and continue stirring to obtain super-hydrophobic water-based emulsion. 7. the application of the superhydrophobic aqueous emulsion for cement-based materials described in claim 1-6 in the construction engineering field. 8. The application according to claim 7, characterized in that it is used in cement concrete. 9. application according to claim 8, is characterized in that, the massfraction of described superhydrophobic aqueous emulsion in cement concrete is 0.5～3%.

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