Slow-release hydrophobic microcapsule and preparation method of cement-based material thereof

Abstract

The invention discloses a slow-release hydrophobic microcapsule and a preparation method of a cement-based material thereof. Wherein the microcapsule wall structure is mainly an interpenetrating network structure formed by polyvinyl alcohol and sodium alginate, the polyvinyl alcohol is cross-linked by boric acid, the sodium alginate is cross-linked by calcium ions, and the cross-linked polyvinyl alcohol and sodium alginate are linked through hydrogen-bond interaction to form an interpenetrating network system. And meanwhile, the carboxymethyl cellulose serving as a thickening agent and a stabilizing agent can promote the formation of the microspheres and increase the strength of the microspheres in the process of synthesizing the microcapsule wall material. Hydroxyl-terminated polydimethylsiloxane is wrapped in the microcapsule, and a hydroxyl group of the hydroxyl-terminated polydimethylsiloxane reacts with a carboxyl group in sodium alginate, so that the hydroxyl-terminated polydimethylsiloxane is wrapped in the microcapsule. The microcapsule is doped into a neat paste test block to prepare a cement-based material, the cement-based material can be normally hydrated to ensure the strength, and meanwhile, the cement-based material has a hydrophobic characteristic in the service period to prevent invasion of water and corrosive ions and adhesion of inorganic matters and microorganisms.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and specifically discloses a slow-release hydrophobic microcapsule and a method for preparing a cement-based material using the microcapsule. Background Art

[0002] At different stages of the life cycle of cement-based materials, their surface wettability needs to present differentiated characteristics: hydrophilic properties need to be maintained during hydration reactions and microstructure formation to ensure that water molecules fully participate in the formation of the cementitious phase and the development of the crystal structure; and during the service stage, they need to be converted into hydrophobic surface properties, aiming to reduce the surface energy barrier effect, inhibit the capillary penetration of external moisture and corrosive ions into the internal pore network, and weaken the van der Waals force and electrostatic interaction, thereby reducing the adhesion tendency of inorganic salt deposits and microbial flora on the material surface.

[0003] The hydrophobic modification of cement-based materials can be divided into two categories: surface modification and overall modification. The method of preparing hydrophobic cement-based materials by surface modification only involves the surface layer, so when cracks or surface wear occur, the exposed internal structure will show the original hydrophilicity and lose the hydrophobic effect; the hydrophobic cement-based materials prepared by overall modification often lead to insufficient cement hydration in the cement-based materials, thereby reducing the mechanical properties of the cement-based materials. Summary of the invention

[0004] Technical problem: The present invention discloses a method for preparing a sustained-release hydrophobic microcapsule and a cement-based material thereof. The sustained-release hydrophobic microcapsule doped into the cement-based material can ensure the normal hydration of the cement-based material, thereby ensuring the strength of the cement-based material, while slowly releasing the internal hydrophobic substance to complete the overall hydrophobicity transformation of the cement-based material after a period of time, giving the material excellent hydrophobic effect and waterproof penetration performance.

[0005] Technical solution: A method for preparing a sustained-release hydrophobic microcapsule of the present invention comprises the following steps:

[0006] Step 1. Add polyvinyl alcohol into deionized water, and fully dissolve the polyvinyl alcohol in the deionized water by heating and magnetic stirring;

[0007] Step 2. Add sodium alginate into deionized water and fully dissolve the sodium alginate in the deionized water by a mechanical stirrer;

[0008] Step 3. adding carboxymethyl cellulose to deionized water, and heating and magnetic stirring to obtain a carboxymethyl cellulose solution;

[0009] Step 4. Add the emulsifier OP-10 into deionized water first, and then add the hydroxyl-terminated polydimethylsiloxane under strong stirring to prepare an emulsion system;

[0010] Step 5. preparing a first mixed solution of boric acid and calcium chloride under stirring;

[0011] Step 6. Mix the materials obtained in steps 1, 2, 3, and 4 to obtain a second mixed solution;

[0012] Step 7. Add the second mixed solution of step 6 to the first mixed solution of step 5, stir with a magnetic stirrer, and after the reaction is completed, perform vacuum filtration at room temperature, wash, and dry to obtain a microcapsule product.

[0013] in,

[0014] The specific steps of step 1 are: at room temperature, 4 to 10 parts of polyvinyl alcohol are weighed by weight and added to 100 parts of deionized water, and stirred at 65-75 degrees Celsius for 1-2 hours by a magnetic stirrer to completely dissolve it to obtain a polyvinyl alcohol solution.

[0015] The specific steps of step 2 are: weigh 2 to 5 parts of sodium alginate by weight, add it to 100 parts of deionized water, and use a mechanical stirrer at 80 degrees Celsius to obtain a sodium alginate solution.

[0016] The specific steps of step 3 are: weigh 1 to 2 parts of carboxymethyl cellulose by weight, add it to 100 parts of deionized water, and stir it with a magnetic stirrer at 20-30 degrees Celsius for 30-60 minutes to obtain a carboxymethyl cellulose solution.

[0017] The specific steps of step 4 are: first weigh 1 part of emulsifier OP-10 by weight and add it to 100 parts of deionized water, and then add 5 parts of hydroxyl-terminated polydimethylsiloxane under high-speed and strong stirring to form an emulsion system.

[0018] The specific steps of step 5 are: weighing 6 parts of boric acid by weight and dissolving them in 100 parts of deionized water to obtain a boric acid solution; weighing 6 parts of calcium chloride by weight and dissolving them in 100 parts of deionized water to obtain a calcium chloride solution; taking 10 parts of the boric acid solution and 10 parts of the calcium chloride solution respectively and mixing them under the action of a magnetic stirrer to form the desired first mixed solution.

[0019] The specific steps of step 6 are: weigh 10 parts by weight of the solutions obtained in steps 1, 2, 3 and 4, and mix them under magnetic stirring to obtain a second mixed solution.

[0020] The specific steps of step 7 are: weigh 10 parts by weight of the second mixed solution obtained in step 7 and drop them into 10 parts of the first mixed solution obtained in step 6. After the reaction is completed, the mixture is filtered under reduced pressure, washed and dried to obtain microcapsules.

[0021] The obtained microcapsules are nearly round in shape, with a particle size of 0.8 mm and a capsule wall structure of an interpenetrating network system.

[0022] The method for preparing cement-based materials by using the slow-release hydrophobic microcapsules of the present invention is as follows: the prepared microcapsules are mixed into the clean slurry test block at 0.5-2% of the weight of the clean slurry test block to obtain the cement-based material.

[0023] Beneficial effects: Compared with the prior art, the present invention has at least the following advantages:

[0024] The cement-based product of the present invention can ensure normal hydration to give it good mechanical strength, and can also exhibit hydrophobic properties during service to inhibit the capillary penetration of external moisture and corrosive ions into the internal pore network, thus overcoming the shortcomings of surface modification and overall modification of traditional cement-based materials. This is because the sustained-release hydrophobic microcapsules of the present invention have the following special properties: first, good sustained-release control ability, the double-layer capsule wall structure of the microcapsules is composed of a mesh structure formed by cross-linking polyvinyl alcohol and boric acid, and an ionic gel network structure formed by cross-linking sodium alginate and calcium chloride. The interpenetrating network structure formed by the multiple cross-linking system effectively limits the diffusion rate of the hydrophobic agent and achieves long-term sustained release; second, excellent alkaline stability, the high pH environment (about 13) of the cement-based system easily destroys the structure of some organic microcapsules, but the polyvinyl alcohol-boric acid cross-linking network has good tolerance in an alkaline environment, and the gel network of calcium alginate can further provide a stable physical barrier, so that the microcapsules maintain structural integrity in a cement-based environment; third, suitable mechanical properties, the cross-linking network of polyvinyl alcohol provides a certain flexibility to the microcapsules, and the ionic cross-linking layer of sodium alginate-calcium chloride gives the microcapsules a higher mechanical strength, so that it will not break in advance during concrete mixing and hardening, ensuring the effective release of the hydrophobic agent. At the same time, the present invention also introduces carboxymethyl cellulose into the microcapsule wall material, further improving the alkali resistance and mechanical strength of the sustained-release microcapsules. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a photograph of the sustained-release hydrophobic microcapsules synthesized in Example 5 of the present invention;

[0026] Figure 2 is the contact angle of the modified cement-based material prepared in Example 5 of the present invention on the 19th day of curing;

[0027] Figure 3 is the change in contact angle of the modified cement-based material prepared in Example 5 of the present invention and the control group after curing for different time periods;

[0028] Figure 4 is the compressive strength of the modified cement-based material prepared in Example 5 of the present invention and the control group after curing for different times;

[0029] Figure 5 It is a microscopic schematic diagram of the sustained-release hydrophobic microcapsules synthesized in Example 5 of the present invention;

[0030] Figure 6 This is a schematic diagram of the cement-based material prepared in Example 5 of the present invention before and after service. Specific implementation methods

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and the best embodiments.

[0033] The present invention provides a method for preparing a sustained-release hydrophobic microcapsule and a cement-based material thereof, which comprises a capsule core material of hydroxyl-terminated polydimethylsiloxane, a capsule wall material of polyvinyl alcohol, sodium alginate and carboxymethyl cellulose. The microcapsule wall structure is mainly an interpenetrating network structure formed by polyvinyl alcohol and sodium alginate, the polyvinyl alcohol is cross-linked by boric acid, the sodium alginate is cross-linked by calcium ions, and the cross-linked polyvinyl alcohol and sodium alginate are linked together by hydrogen bonding to form an interpenetrating network system. At the same time, the carboxymethyl cellulose in the wall material can promote the formation of microspheres and increase the strength of the microspheres in the process of synthesizing microcapsules as a thickener and stabilizer. Hydroxyl-terminated polydimethylsiloxane is encapsulated in the microcapsule, and its hydroxyl group reacts with the carboxyl group in the sodium alginate to be encapsulated inside the microcapsule.

[0034] Example 1: A sustained-release hydrophobic microcapsule for cement-based materials and a preparation method thereof comprises the following steps:

[0035] (1) Weigh 4 parts of polyvinyl alcohol, 2 parts of sodium alginate, and 1 part of carboxymethyl cellulose, respectively, and dissolve them in 100 parts of deionized water and stir them under heating conditions, wherein the temperature for dissolving the polyvinyl alcohol is set at 65-75 degrees Celsius, the speed is set at 800 r / min, and the time is 1-2 hours; wherein the temperature for dissolving the sodium alginate is set at 80 degrees Celsius, the speed is set at 1200 r / min, and the time is 30-40 minutes. It should be noted that the sodium alginate is added to the deionized water in 4 portions to facilitate dissolution; wherein the temperature for dissolving the carboxymethyl cellulose is set at 20-30 degrees Celsius, the speed is set at 800 r / min, and the time is 30-60 minutes; take 1 part of each of the three solutions to prepare a mixed solution for standby use.

[0036] (2) First, weigh 1 part of emulsifier OP-10 and add it to 100 parts of deionized water at 800 r / min, then increase the speed to 1600 r / min, set the temperature at 20-25 degrees Celsius, add 5 parts of hydroxyl-terminated polydimethylsiloxane and react for 15-20 minutes; after the emulsion is formed, let it stand for 3 hours to ensure the stability of the emulsion and set aside.

[0037] (3) Under the condition of 500 r / min, weigh 6 parts of calcium chloride and 6 parts of boric acid and dissolve them in 100 parts of deionized water respectively to prepare two solutions; then take 10 parts of each of the two solutions to prepare a mixed solution for later use.

[0038] (4) Take 10 parts of the solutions prepared in steps (1) and (2) to form a mixed solution, and add it dropwise into the mixed solution prepared in step (3) at 800 r / min to form microcapsules; filter under reduced pressure, wash and dry to obtain the desired product.

[0039] The prepared sustained-release hydrophobic microcapsules were placed in a simulated pore solution, where the microcapsules could exist stably for 3 days. The simulated pore solution contained 0.002 mol / L Ca(OH) 2 , 0.25mol / L NaOH, 0.54mol / L KOH, and 0.003mol / L K 2 SO 4 of mixed solution.

[0040] Example 2: A sustained-release hydrophobic microcapsule for cement-based materials and a preparation method thereof, comprising the following steps:

[0041] (1) Weigh 6 parts of polyvinyl alcohol, 3 parts of sodium alginate, and 1 part of carboxymethyl cellulose and dissolve them in 100 parts of deionized water respectively, and stir them under heating conditions, wherein the temperature for dissolving the polyvinyl alcohol is set at 65-75 degrees Celsius, the speed is set at 800 r / min, and the time is 1-2 hours; wherein the temperature for dissolving the sodium alginate is set at 80 degrees Celsius, the speed is set at 1200 r / min, and the time is 30-40 minutes. It should be noted that the sodium alginate is added to the deionized water in 4 portions to facilitate dissolution; wherein the temperature for dissolving the carboxymethyl cellulose is set at 20-30 degrees Celsius, the speed is set at 800 r / min, and the time is 30-60 minutes; take 1 part of each of the three solutions to prepare a mixed solution for standby use.

[0042] (2) First, weigh 1 part of emulsifier OP-10 and add it to 100 parts of deionized water at 800 r / min, then increase the speed to 1600 r / min, set the temperature at 20-25 degrees Celsius, add 5 parts of hydroxyl-terminated polydimethylsiloxane and react for 15-20 minutes; after the emulsion is formed, let it stand for 3 hours to ensure the stability of the emulsion and set aside.

[0043] (3) Under the condition of 500 r / min, weigh 6 parts of calcium chloride and 6 parts of boric acid and dissolve them in 100 parts of deionized water respectively to prepare two solutions; then take 10 parts of each of the two solutions to prepare a mixed solution for later use.

[0044] (4) Take 10 parts of the solutions prepared in steps (1) and (2) to form a mixed solution, and add it dropwise into the mixed solution prepared in step (3) at 800 r / min to form microcapsules; filter under reduced pressure, wash and dry to obtain the desired product.

[0045] The prepared sustained-release hydrophobic microcapsules were placed in a simulated pore solution, where the microcapsules could exist stably for 5 days. The simulated pore solution contained 0.002 mol / L Ca(OH) 2 , 0.25mol / L NaOH, 0.54mol / L KOH, and 0.003mol / L K 2 SO 4 of mixed solution.

[0046] Example 3: A sustained-release hydrophobic microcapsule for cement-based materials and a preparation method thereof, comprising the following steps:

[0047] (1) Weigh 8 parts of polyvinyl alcohol, 4 parts of sodium alginate, and 1 part of carboxymethyl cellulose, respectively, and dissolve them in 100 parts of deionized water, and stir them under heating conditions. The temperature for dissolving the polyvinyl alcohol is set at 65-75 degrees Celsius, the speed is set at 800 r / min, and the time is 1-2 hours; the temperature for dissolving the sodium alginate is set at 80 degrees Celsius, the speed is set at 1200 r / min, and the time is 30-40 minutes. It should be noted that the sodium alginate is added to the deionized water in 4 portions to facilitate dissolution; the temperature for dissolving the carboxymethyl cellulose is set at 20-30 degrees Celsius, the speed is set at 800 r / min, and the time is 30-60 minutes; take 1 part of each of the three solutions to prepare a mixed solution for standby use.

[0048] (2) First, weigh 1 part of emulsifier OP-10 and add it to 100 parts of deionized water at 800 r / min, then increase the speed to 1600 r / min, set the temperature at 20-25 degrees Celsius, add 5 parts of hydroxyl-terminated polydimethylsiloxane and react for 15-20 minutes; after the emulsion is formed, let it stand for 3 hours to ensure the stability of the emulsion and set aside.

[0049] (3) Under the condition of 500 r / min, weigh 6 parts of calcium chloride and 6 parts of boric acid and dissolve them in 100 parts of deionized water respectively to prepare two solutions; then take 10 parts of each of the two solutions to prepare a mixed solution for later use.

[0050] (4) Take 10 parts of the solutions prepared in steps (1) and (2) to form a mixed solution, and add it dropwise into the mixed solution prepared in step (3) at 800 r / min to form microcapsules; filter under reduced pressure, wash and dry to obtain the desired product.

[0051] The prepared sustained-release hydrophobic microcapsules were placed in a simulated pore solution, where the microcapsules could be stably present for 9 days. The simulated pore solution contained 0.002 mol / L Ca(OH) 2 , 0.25mol / L NaOH, 0.54mol / L KOH, and 0.003mol / L K 2 SO 4 of mixed solution.

[0052] Example 4: A sustained-release hydrophobic microcapsule for cement-based materials and a preparation method thereof, comprising the following steps:

[0053] (1) Weigh 10 parts of polyvinyl alcohol, 5 parts of sodium alginate, and 1 part of carboxymethyl cellulose and dissolve them in 100 parts of deionized water respectively, and stir them under heating conditions, wherein the temperature for dissolving the polyvinyl alcohol is set at 65-75 degrees Celsius, the speed is set at 800 r / min, and the time is 1-2 hours; wherein the temperature for dissolving the sodium alginate is set at 80 degrees Celsius, the speed is set at 1200 r / min, and the time is 30-40 minutes. It should be noted that the sodium alginate is added to the deionized water in 4 portions to facilitate dissolution; wherein the temperature for dissolving the carboxymethyl cellulose is set at 20-30 degrees Celsius, the speed is set at 800 r / min, and the time is 30-60 minutes; take 1 part of each of the three solutions to prepare a mixed solution for standby use.

[0054] (2) First, weigh 1 part of emulsifier OP-10 and add it to 100 parts of deionized water at 800 r / min, then increase the speed to 1600 r / min, set the temperature at 20-25 degrees Celsius, add 5 parts of hydroxyl-terminated polydimethylsiloxane and react for 15-20 minutes; after the emulsion is formed, let it stand for 3 hours to ensure the stability of the emulsion and set aside.

[0055] (3) Under the condition of 500 r / min, weigh 6 parts of calcium chloride and 6 parts of boric acid and dissolve them in 100 parts of deionized water respectively to prepare two solutions; then take 10 parts of each of the two solutions to prepare a mixed solution for later use.

[0056] (4) Take 10 parts of the solutions prepared in steps (1) and (2) to form a mixed solution, and add it dropwise into the mixed solution prepared in step (3) at 800 r / min to form microcapsules; filter under reduced pressure, wash and dry to obtain the desired product.

[0057] The prepared sustained-release hydrophobic microcapsules were placed in a simulated pore solution, where the microcapsules could be stably present for 11 days. The simulated pore solution contained 0.002 mol / L Ca(OH) 2 , 0.25mol / LNaOH, 0.54mol / LKOH, and 0.003mol / LK 2 SO4 of mixed solution.

[0058] Example 5: A sustained-release hydrophobic microcapsule for cement-based materials and a preparation method thereof, comprising the following steps:

[0059] (1) Weigh 10 parts of polyvinyl alcohol, 5 parts of sodium alginate, and 2 parts of carboxymethyl cellulose and dissolve them in 100 parts of deionized water respectively, and stir them under heating conditions, wherein the temperature for dissolving polyvinyl alcohol is set at 65-75 degrees Celsius, the speed is set at 800 r / min, and the time is 1-2 hours; wherein the temperature for dissolving alginic acid is set at 80 degrees Celsius, the speed is set at 1200 r / min, and the time is 30-40 minutes. It should be noted that sodium alginate is added to deionized water in 4 portions to facilitate dissolution; wherein the temperature for dissolving carboxymethyl cellulose is set at 20-30 degrees Celsius, the speed is set at 800 r / min, and the time is 30-60 minutes; take 1 part of each of the three solutions to prepare a mixed solution for standby use.

[0060] (2) First, weigh 1 part of emulsifier OP-10 and add it to 100 parts of deionized water at 800 r / min, then increase the speed to 1600 r / min, set the temperature at 20-25 degrees Celsius, add 5 parts of hydroxyl-terminated polydimethylsiloxane and react for 15-20 minutes; after the emulsion is formed, let it stand for 3 hours to ensure the stability of the emulsion and set aside.

[0061] (3) Under the condition of 500 r / min, weigh 6 parts of calcium chloride and 6 parts of boric acid and dissolve them in 100 parts of deionized water respectively to prepare two solutions; then take 10 parts of each of the two solutions to prepare a mixed solution for later use.

[0062] (4) Take 10 parts of the solutions prepared in steps (1) and (2) to form a mixed solution, and add it dropwise into the mixed solution prepared in step (3) at 800 r / min to form microcapsules; filter under reduced pressure, wash and dry to obtain the desired product.

[0063] (5) Two types of 40 mm*40 mm*40 mm concrete paste specimens with a water-cement ratio of 0.5 were prepared, one group without doping with sustained-release hydrophobic microcapsules as a control group, and one group doped with microcapsules as an experimental group.

[0064] The prepared sustained-release hydrophobic microcapsules were placed in a simulated pore solution, and the microcapsules could exist stably for 19 days. The composition of the simulated pore solution was 0.002 mol / L Ca(OH) 2 , 0.25mol / LNaOH, 0.54mol / LKOH, and 0.003mol / LK 2 SO 4 of mixed solution.

[0065] Figure 1 This is a photo of the sustained-release hydrophobic microcapsules synthesized in Example 5 of the present invention. As can be seen from the photo, the sustained-release hydrophobic microcapsules are round and coated with emulsified hydroxyl-terminated polydimethylsiloxane (milky white).

[0066] Figure 2 It is the contact angle of the modified cement-based material prepared in Example 5 of the present invention on the 19th day of curing. As can be seen from the picture, the test block of the experimental group exhibits excellent hydrophobic performance after 19 days of curing.

[0067] Figure 3 The contact angle changes of the modified cement-based material prepared in Example 5 of the present invention and the control group at different curing times. As can be seen from the picture, the overall wettability transformation of the pure slurry test block occurred around the 17th day.

[0068] Figure 4 It is the compressive strength of the modified cement-based material prepared in Example 5 of the present invention and the control group after curing for different times. As can be seen from the picture, the strength of the modified pure slurry test block is slightly lower than that of the control group.

[0069] Figure 5 It is a microscopic schematic diagram of the sustained-release hydrophobic microcapsules synthesized in Example 5 of the present invention.

[0070] Figure 6 This is a schematic diagram of the cement-based material prepared in Example 5 of the present invention before and after service.

Claims

1. A method for preparing sustained-release hydrophobic microcapsules, characterized in that: The steps include: Step 1. Add polyvinyl alcohol into deionized water, and fully dissolve the polyvinyl alcohol in the deionized water by heating and magnetic stirring; Step 2. Add sodium alginate into deionized water and fully dissolve the sodium alginate in the deionized water by a mechanical stirrer; Step 3. adding carboxymethyl cellulose to deionized water, and heating and magnetic stirring to obtain a carboxymethyl cellulose solution; Step 4. Add the emulsifier OP-10 into deionized water first, and then add the hydroxyl-terminated polydimethylsiloxane under strong stirring to prepare an emulsion system; Step 5. preparing a first mixed solution of boric acid and calcium chloride under stirring; Step 6. Mix the materials obtained in steps 1, 2, 3, and 4 to obtain a second mixed solution; Step 7. Add the second mixed solution of step 6 to the first mixed solution of step 5, stir with a magnetic stirrer, and after the reaction is completed, perform vacuum filtration at room temperature, wash, and dry to obtain a microcapsule product.

2. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 1 are: at room temperature, 4 to 10 parts of polyvinyl alcohol are weighed by weight and added to 100 parts of deionized water, and stirred at 65-75 degrees Celsius for 1-2 hours by a magnetic stirrer to completely dissolve it to obtain a polyvinyl alcohol solution.

3. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 2 are: weigh 2 to 5 parts of sodium alginate by weight, add it to 100 parts of deionized water, and use a mechanical stirrer at 80 degrees Celsius to obtain a sodium alginate solution.

4. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 3 are: weigh 1 to 2 parts of carboxymethyl cellulose by weight, add it to 100 parts of deionized water, and stir it with a magnetic stirrer at 20-30 degrees Celsius for 30-60 minutes to obtain a carboxymethyl cellulose solution.

5. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 4 are: first weigh 1 part of emulsifier OP-10 by weight and add it to 100 parts of deionized water, and then add 5 parts of hydroxyl-terminated polydimethylsiloxane under high-speed and strong stirring to form an emulsion system.

6. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 5 are: weighing 6 parts of boric acid by weight and dissolving them in 100 parts of deionized water to obtain a boric acid solution; weighing 6 parts of calcium chloride by weight and dissolving them in 100 parts of deionized water to obtain a calcium chloride solution; taking 10 parts of the boric acid solution and 10 parts of the calcium chloride solution respectively and mixing them under the action of a magnetic stirrer to form the desired first mixed solution.

7. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 6 are: weigh 10 parts by weight of the solutions obtained in steps 1, 2, 3 and 4, and mix them under magnetic stirring to obtain a second mixed solution.

8. The method for preparing sustained-release hydrophobic microcapsules according to claim 1, characterized in that: The specific steps of step 7 are: weigh 10 parts by weight of the second mixed solution obtained in step 7 and drop them into 10 parts of the first mixed solution obtained in step 6. After the reaction is completed, the mixture is filtered under reduced pressure, washed and dried to obtain microcapsules.

9. The method for preparing sustained-release hydrophobic microcapsules according to claim 8, characterized in that: The obtained microcapsules are nearly round in shape, with a particle size of 0.8 mm and a capsule wall structure of an interpenetrating network system.

10. A method for preparing cement-based materials using the sustained-release hydrophobic microcapsules according to any one of claims 1 to 9, characterized in that: The prepared microcapsules are mixed into the clean slurry test block at 0.5-2% of the weight of the clean slurry test block to obtain a cement-based material.

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