Microcapsule sustained-release material as well as preparation method and application thereof

Abstract

The invention relates to the field of temperature control and crack prevention of concrete, in particular to a microcapsule sustained-release material as well as a preparation method and application thereof. The microcapsule sustained-release material comprises an inner core and a coating layer, the inner core comprises a porous carbon material and a temperature suppression material, and the coating layer is a hot melt adhesive film. The microcapsule sustained-release material disclosed by the invention can realize three-stage sustained release of superposition of heat release, porous structure sustained release and temperature suppression material dissolution sustained release, and has a lasting and excellent temperature suppression effect; when the early temperature is low, the temperature suppression material is not consumed, concrete coagulation and demolding are basically not affected, the temperature suppression material is continuously released at the later high-temperature section, the highest temperature of the concrete is reduced, and the temperature shrinkage cracking risk of the concrete is reduced.

Description

Technical Field

[0001] The invention relates to the field of concrete temperature control and crack prevention, and in particular to a microcapsule sustained-release material and a preparation method and application thereof. Background Art

[0002] During the hydration process, cementitious materials release a large amount of hydration heat, which causes the concrete temperature to rise. During the cooling process, the structure in the restrained state is prone to thermal shrinkage and cracking. In recent years, medium-sized structures using high-strength concrete, such as tunnel linings, subway corridor side walls, and civil engineering basement exterior walls, have been affected by large cement consumption, ultra-fine cement, and C 3 Due to unfavorable factors such as high S content, the phenomenon of temperature shrinkage cracking is increasing. However, the existing materials used for temperature control and crack prevention of medium-sized concrete structures have the defect of poor temperature suppression effect, and the effect of suppressing concrete temperature shrinkage cracking is poor. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect of poor temperature suppression effect of the temperature control and crack prevention material in the prior art, thereby providing a microcapsule sustained-release material and a preparation method and application thereof.

[0004] To this end, the present invention provides the following technical solutions:

[0005] The invention provides a microcapsule sustained-release material, which comprises a core and a coating layer; the core comprises a porous carbon material and a temperature-suppressing material, and the coating layer is a hot-melt adhesive film.

[0006] In an optional embodiment, the mass ratio of the temperature suppression material, the porous carbon material and the hot melt adhesive film is (55-80): (40-50): (3-5).

[0007] Optionally, the particle size of the microcapsule sustained-release material is 0.05-0.6 mm.

[0008] Optionally, the microcapsule sustained-release material is divided according to particle size, including a first microcapsule sustained-release material, a second microcapsule sustained-release material and a third microcapsule sustained-release material; the particle size a of the first microcapsule sustained-release material is 0.05mm≤a<0.1mm; the particle size b of the second microcapsule sustained-release material is 0.1mm≤b<0.3mm; and the particle size c of the third microcapsule sustained-release material is 0.3mm≤c≤0.6mm.

[0009] Optionally, the mass ratio of the first microcapsule sustained-release material, the second microcapsule sustained-release material and the third microcapsule sustained-release material is (0.5-1.5):(0.5-1.5):(0.5-1.5).

[0010] The present invention further enhances the sustained-release effect (small-size particles are preferentially released, and large-size particles are slowly released) by setting a specific particle size gradation and using microcapsule sustained-release materials of different particle sizes for matching.

[0011] The particle size of the microcapsule sustained-release material in the present invention is controlled by conventional technical means in the art, and the microcapsule sustained-release material with a specific particle size distribution of the present invention can be obtained by adjusting the granulation process during the preparation process or performing screening and combination after the preparation.

[0012] In an optional embodiment, the temperature-suppressing material includes modified starch.

[0013] Optionally, the modification method of the starch in the modified starch includes one or more of physical denaturation, chemical denaturation and enzymatic denaturation; the physical denaturation, chemical denaturation and enzymatic denaturation can be carried out by conventional methods in the art.

[0014] Optionally, the modified starch includes one or more of hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin.

[0015] Optionally, the modified starch includes hydroxypropyl distarch phosphate, sodium starch octenylsuccinate and yellow dextrin.

[0016] Optionally, the mass ratio of hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin is (10-20): (15-20): (30-40).

[0017] In an optional embodiment, the porous carbon material includes one or more of activated carbon, carbon nanotubes, carbon aerogel and biochar.

[0018] Optionally, the biochar comprises sewage sludge derived carbon material.

[0019] Optionally, the method for preparing the sludge-derived carbon material comprises the following steps: sintering the sludge under a protective atmosphere to obtain the sludge-derived carbon material.

[0020] Optionally, the protective atmosphere includes nitrogen or an inert atmosphere; the inert atmosphere includes argon or helium.

[0021] Optionally, the sintering temperature is 800-1000° C. and the sintering time is 1-2 h.

[0022] In an optional embodiment, the melting point of the hot melt adhesive film is 50-65°C.

[0023] Optionally, the hot melt adhesive film is a TPU (thermoplastic polyurethane elastomer) hot melt adhesive film.

[0024] In another aspect, the present invention provides a method for preparing the microcapsule sustained-release material, comprising the following steps:

[0025] The temperature-suppressing material, the porous carbon material and water are mixed and granulated to obtain granules;

[0026] The granules are mixed with a molten hot melt adhesive film to prepare a microcapsule sustained-release material.

[0027] In an optional embodiment, the step of mixing the temperature-suppressing material, the porous carbon material and water and granulating to obtain granules comprises:

[0028] Mixing the temperature-suppressing material and water to obtain a first mixed solution;

[0029] After the first mixed liquid is heated to a target temperature, it is mixed with a porous carbon material to obtain a second mixed liquid, which is then granulated to obtain pellets.

[0030] Optionally, the first mixed liquid has a solid content of 25-35%.

[0031] Optionally, the target temperature is 50-60°C.

[0032] In an optional embodiment, the porous carbon material further includes an acid washing process before use, and the purpose of the acid washing is to obtain more pores.

[0033] Optionally, the pickling reagent includes a sulfuric acid solution, and the concentration of the sulfuric acid solution is 0.8-1.2 mol / L.

[0034] The present invention does not impose any particular limitation on the amount of the pickling reagent, as long as it can completely immerse the porous carbon material.

[0035] Optionally, the pickling temperature is 20-30°C and the time is 22-26h.

[0036] Optionally, the granulation method is centrifugal spray granulation.

[0037] Optionally, after granulation, cooling is performed to obtain pellets.

[0038] Optionally, the cooling method is natural cooling or air cooling, and the cooling target temperature is ≤30°C.

[0039] Optionally, air cooling is performed by introducing room temperature air into the pellets. The present invention does not impose any particular limitation on the rate at which room temperature air is introduced, and it is only necessary to cool the pellets to a target temperature.

[0040] In an optional implementation, the molten hot melt adhesive film is obtained by preheating the hot melt adhesive film.

[0041] Optionally, the preheating temperature is 90-110°C.

[0042] Optionally, the pellets are mixed with the molten hot melt adhesive film at a rotation speed of 250-350 r / min; and the mixture is mixed until a homogeneous mixture is formed.

[0043] Optionally, the mixing time is 5-10 minutes.

[0044] In an optional embodiment, the granules are mixed with a hot melt adhesive film and sealed by mechanical friction to obtain a microcapsule sustained-release material.

[0045] The present invention also provides application of the microcapsule sustained-release material or the microcapsule sustained-release material prepared by the preparation method in controlling concrete temperature shrinkage cracking.

[0046] In an optional embodiment, the concrete includes concrete for tunnel lining, concrete for subway tunnel side walls, or concrete for industrial and civil basement exterior walls.

[0047] The technical solution of the present invention has the following advantages:

[0048] 1. The present invention provides a microcapsule sustained-release material, which comprises a core and a coating layer; the core comprises a porous carbon material and a temperature-suppressing material, and the coating layer is a hot-melt adhesive film.

[0049] Microcapsule sustained-release materials can achieve three-level sustained-release, namely, thermal release, porous structure sustained-release, and temperature-inhibiting material dissolution sustained-release, and have a long-lasting and excellent temperature-inhibiting effect. Specifically, after the microcapsule sustained-release material is added to the concrete, it is not released directly, and the cement hydration process is not affected at this time; as the cement hydration temperature rises, when the temperature rises to 40-50°C, the outermost hot-melt adhesive film melts first, opening the surface pores of the porous carbon material, and the temperature-inhibiting material (modified starch) near the surface quickly wraps around the surface of the cement particles to form a complex, inhibiting cement hydration, which is a release; the cement continues to hydrate and will break through the complex coating. At this time, the temperature-inhibiting material inside the porous carbon material will be released from the inside due to the concentration difference, and continue to inhibit hydration, which is a secondary release; at the same time, the temperature-inhibiting material itself increases in solubility as the temperature rises, forming a tertiary release; in this way, a three-level sustained-release structure is formed. As the temperature increases, more is released, and the inhibition is stronger, so that when the temperature is low in the early stage, the temperature-inhibiting material is not consumed, which basically does not affect the concrete coagulation and demolding, and is continuously released in the later high-temperature stage, reducing the maximum temperature of the concrete and reducing the risk of concrete temperature shrinkage and cracking.

[0050] 2. The temperature-suppressing material of the present invention includes modified starch, and the modified starch includes hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin. The mass ratio of hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin is (10-20): (15-20): (30-40). Hydroxypropyl distarch phosphate is a modified starch cross-linked with phosphate. Phosphate has a good temperature-suppressing effect on cement hydration. The temperature-suppressing effect of hydroxypropyl distarch phosphate after phosphate cross-linking and hydroxypropyl etherification is better than that of conventional modified starch; sodium starch octenyl succinate has the characteristics of being hydrophobic and lipophilic, and dissolving after heating, and can achieve sustained release during the hydration and temperature rise process; compared with the first two, yellow dextrin has a smaller weight and a faster dissolution rate. The three can be combined at different mass ratios to form a sustained-release combination with different dissolution rates.

[0051] 3. The porous carbon material of the present invention includes one or more of activated carbon, carbon nanotubes, carbon aerogel and biochar, and the biochar includes sludge-derived carbon material. Biochar itself has the advantages of wide sources, renewability, and environmental protection, and the sludge-derived carbon material can achieve adjustable pore size during the preparation process, which is conducive to the preparation of the microcapsule sustained-release material of the present invention.

[0052] 4. The hot melt adhesive film of the present invention is a TPU hot melt adhesive film, which has excellent mechanical properties and durability, becomes sticky when heated, and dries quickly after cooling, and is suitable for preparing the microcapsule sustained-release material of the present invention.

[0053] 5. The present invention provides a method for preparing a microcapsule sustained-release material, comprising the following steps: mixing and granulating the temperature-suppressing material, porous carbon material and water to obtain granules; mixing the granules with a molten hot-melt adhesive film to obtain a microcapsule sustained-release material. The present invention adopts a two-time encapsulation process, the first encapsulation: the porous carbon material is encapsulated in the temperature-suppressing material by mixing and granulating; the second encapsulation: the hot-melt adhesive film is encapsulated by high-speed stirring mechanical friction.

[0054] 6. The present invention sets the particle size of the final microcapsule sustained-release material to 0.05-0.6 mm. Within this particle size range, the microcapsule sustained-release material has the best sustained-release effect and temperature-suppressing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1It is a schematic diagram of the temperature rise of a single cement, a first mixed material and a second mixed material in the present invention;

[0057] Figure 2 It is a schematic diagram of the temperature rise of a single cement and a third mixed material in the present invention;

[0058] Figure 3 It is a schematic diagram of the temperature rise of a single cement and a fourth mixed material in the present invention;

[0059] Figure 4 It is a schematic diagram of the temperature rise of a single cement, a fifth mixed material and a sixth mixed material in the present invention;

[0060] Figure 5 It is the temperature and stress curve diagram of two concrete specimens in the present invention. DETAILED DESCRIPTION

[0061] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0062] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0063] In the examples of the present invention, hydroxypropyl distarch phosphate was purchased from Hangzhou Prostar Starch Co., Ltd., model number HP-CF W0390;

[0064] Sodium starch octenylsuccinate was purchased from Hangzhou Ruilin Chemical Co., Ltd., model SS0S-A;

[0065] Yellow dextrin was purchased from Shandong Chengshun Chemical Technology Co., Ltd.;

[0066] The sludge comes from Zhuhai Weiligao Biotechnology Co., Ltd.;

[0067] TPU hot melt adhesive film was purchased from Dongguan Meidinglian New Materials Co., Ltd. with a melting point of 50-65°C.

[0068] Example 1

[0069] This embodiment provides a method for preparing a microcapsule sustained-release material, comprising the following steps:

[0070] In a nitrogen atmosphere, the sludge was sintered at 900°C for 1.5 hours to obtain a sludge-derived carbon material; the sludge-derived carbon material was immersed in a 1 mol / L sulfuric acid solution at a temperature of 25°C for 24 hours to obtain an acid-washed sludge-derived carbon material;

[0071] Mix 10g of hydroxypropyl distarch phosphate, 20g of sodium starch octenylsuccinate, 30g of yellow dextrin and water to obtain a first mixed solution with a mass solid content of 30%; heat the first mixed solution to 50°C, mix it with 40g of acid-washed sludge-derived carbon material to obtain a second mixed solution, and then perform centrifugal spray granulation. After the granulation is completed, naturally cool it to 25°C to obtain pellets; preheat the TPU hot melt adhesive film to 100°C, add 5g of the preheated TPU hot melt adhesive film to the high-speed stirred pellets, stir at a speed of 300r / min, stir for 10min, and obtain a microcapsule sustained-release material by mechanical friction sealing.

[0072] The particle size of the microcapsule sustained-release material is 0.05-0.6mm (the particle size a of the first microcapsule sustained-release material is 0.05mm≤a<0.1mm; the particle size b of the second microcapsule sustained-release material is 0.1mm≤b<0.3mm; the particle size c of the third microcapsule sustained-release material is 0.3mm≤c≤0.6mm; the mass ratio of the first microcapsule sustained-release material, the second microcapsule sustained-release material and the third microcapsule sustained-release material is 1:1:1).

[0073] Example 2

[0074] This embodiment provides a method for preparing a microcapsule sustained-release material, comprising the following steps:

[0075] The same method as in Example 1 was used to prepare the acid-washed sludge-derived carbon material;

[0076] Mix 20g of hydroxypropyl distarch phosphate, 15g of sodium starch octenylsuccinate, 40g of yellow dextrin and water to obtain a first mixed solution with a mass solid content of 28%; heat the first mixed solution to 55°C, mix it with 45g of acid-washed sludge-derived carbon material to obtain a second mixed solution, and then perform centrifugal spray granulation. After the granulation is completed, naturally cool it to 25°C to obtain pellets; preheat the TPU hot melt adhesive film to 95°C, add 4g of the preheated TPU hot melt adhesive film to the high-speed stirred pellets, stir at a speed of 280r / min, stir for 8min, and obtain a microcapsule sustained-release material by mechanical friction sealing.

[0077] The particle size of the microcapsule sustained-release material is 0.05-0.6mm (the particle size a of the first microcapsule sustained-release material is 0.05mm≤a<0.1mm; the particle size b of the second microcapsule sustained-release material is 0.1mm≤b<0.3mm; the particle size c of the third microcapsule sustained-release material is 0.3mm≤c≤0.6mm; the mass ratio of the first microcapsule sustained-release material, the second microcapsule sustained-release material and the third microcapsule sustained-release material is 0.5:0.5:1).

[0078] Example 3

[0079] This embodiment provides a method for preparing a microcapsule sustained-release material, comprising the following steps:

[0080] The same method as in Example 1 was used to prepare the acid-washed sludge-derived carbon material;

[0081] Mix 20g of hydroxypropyl distarch phosphate, 20g of sodium starch octenylsuccinate, 30g of yellow dextrin and water to obtain a first mixed solution with a mass solid content of 33%; heat the first mixed solution to 58°C, mix it with 50g of acid-washed sludge-derived carbon material to obtain a second mixed solution, and then perform centrifugal spray granulation. After the granulation is completed, naturally cool it to 25°C to obtain pellets; preheat the TPU hot melt adhesive film to 105°C, add 3g of the preheated TPU hot melt adhesive film to the high-speed stirred pellets, stir at a speed of 350r / min, stir for 6min, and obtain a microcapsule sustained-release material by mechanical friction sealing.

[0082] The particle size of the microcapsule sustained-release material is 0.05-0.6mm (the particle size a of the first microcapsule sustained-release material is 0.05mm≤a<0.1mm; the particle size b of the second microcapsule sustained-release material is 0.1mm≤b<0.3mm; the particle size c of the third microcapsule sustained-release material is 0.3mm≤c≤0.6mm; the mass ratio of the first microcapsule sustained-release material, the second microcapsule sustained-release material and the third microcapsule sustained-release material is 0.8:1.2:1).

[0083] Comparative Example 1

[0084] The commercially available ordinary cement hydration inhibitor was purchased from Tianjin Baoming Co., Ltd. and the model is BM-Y.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing a temperature-suppressing material, comprising the following steps:

[0087] 10 g of hydroxypropyl distarch phosphate, 20 g of sodium starch octenylsuccinate and 30 g of yellow dextrin were mixed to obtain a temperature-suppressing material.

[0088] Test Example 1

[0089] (1) Cement Standard cement (PI 425, production batch 20230709) was used to mix the cement with the microcapsule sustained-release material prepared in Example 1 to obtain a first mixed material (the amount of the microcapsule sustained-release material in the first mixed material was 0.2 wt %).

[0090] The cement was mixed with the commercially available ordinary cement hydration inhibitor in Comparative Example 1 to obtain a second mixed material (the amount of the commercially available ordinary cement hydration inhibitor in the second mixed material was 0.2 wt %).

[0091] Under a constant temperature of 20°C, the temperature rise of single cement, the first mixed material and the second mixed material were tested in a foam box, and a schematic diagram of the temperature rise of single cement, the first mixed material and the second mixed material was obtained, as shown in FIG. Figure 1 As shown. Figure 1 It can be seen that, on the one hand, compared with the second mixed material, the first mixed material significantly reduces the temperature rise of cement hydration, and the first mixed material achieves a lasting temperature suppression effect. This may be because the commercially available ordinary cement hydration inhibitor in the second mixed material exerts a one-time temperature suppression effect, while the microcapsule sustained-release material in the first mixed material has a three-level sustained release, achieving a lasting and excellent temperature suppression effect; on the other hand, compared with the second mixed material, the first mixed material basically does not affect the coagulation of cement. This shows that the microcapsule sustained-release material prepared in Example 1 can significantly suppress the temperature rise of cement hydration without delaying coagulation, and has a lasting and excellent temperature suppression effect.

[0092] (2) Cement was Jinyu Jidong Cement (P·O 425, production batch 20240311), and the cement was mixed with the microcapsule sustained-release material prepared in Example 2 to obtain a third mixed material (the amount of the microcapsule sustained-release material in the third mixed material was 0.2 wt %). Under a constant temperature of 20° C., the temperature rise of the single cement and the third mixed material was tested in a foam box, and a schematic diagram of the temperature rise of the single cement and the third mixed material was obtained, as shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the microcapsule sustained-release material prepared in Example 2 can significantly inhibit the temperature rise of cement hydration without substantially affecting cement coagulation, and has a long-lasting and excellent temperature-inhibiting effect.

[0093] (3) Cement was Jinyu Jidong cement (P·O 425, production batch 20240728), and the cement was mixed with the microcapsule sustained-release material prepared in Example 3 to obtain a fourth mixed material (the amount of the microcapsule sustained-release material in the fourth mixed material was 0.2 wt %). Under a constant temperature of 20° C., the temperature rise of the single cement and the fourth mixed material was tested in a foam box, and a schematic diagram of the temperature rise of the single cement and the fourth mixed material was obtained, as shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the microcapsule sustained-release material prepared in Example 3 can significantly inhibit the temperature rise of cement hydration without substantially affecting cement coagulation, and has a long-lasting and excellent temperature-inhibiting effect.

[0094] (4) Cement was prepared using Jinyu Jidong cement (P·O 425, production batch 20231105). The cement was mixed with the microcapsule sustained-release material prepared in Example 1 to obtain a fifth mixed material (the amount of the microcapsule sustained-release material in the fifth mixed material was 0.2 wt %).

[0095] The cement was mixed with the temperature-suppressing material in Comparative Example 2 to obtain a sixth mixed material (the amount of the slow-release material in the sixth mixed material was 0.2 wt %).

[0096] Under a constant temperature of 20°C, the temperature rise of the single cement, the fifth mixed material and the sixth mixed material was tested in a foam box, and a schematic diagram of the temperature rise of the single cement, the fifth mixed material and the sixth mixed material was obtained, as shown in FIG. Figure 4 As shown. Figure 4 It can be seen that, on the one hand, compared with the sixth mixed material, the fifth mixed material further reduces the temperature rise of cement hydration and has little effect on coagulation. This further shows that the microcapsule material prepared by adding porous carbon material and hot melt adhesive film has a multi-stage sustained release effect, which can achieve excellent temperature suppression effect without affecting coagulation.

[0097] Test Example 2

[0098] According to the mix ratio in Table 1 (cement is Jinyu Jidong cement (P·O 425, production batch 20231105), water reducer is polycarboxylic acid water reducer, and water reduction rate is 30%), concrete specimens 1 and 2 are prepared in the laboratory, both with dimensions of 1500mm×150mm×150mm; concrete specimens 1 and 2 are subjected to temperature and stress tests using a temperature stress testing machine (HYTSTM-II produced by Beijing Hangyuan Pingyang Technology Development Co., Ltd.), and the temperature and stress curves of the two concrete specimens are obtained, as shown in FIG. Figure 5 As shown; Figure 5 In the figure, the red and black lines are temperature curves; the blue and green lines are stress curves.

[0099] Table 1 Concrete mix ratio

[0100]

[0101] from Figure 5It can be seen that compared with concrete specimen 1, the maximum temperature of concrete specimen 2 is reduced by △T1-10.8℃, which proves that the microcapsule sustained-release material has a good peak-cutting effect. As the temperature drops, at a certain moment, the tensile stress of the concrete specimen will exceed the tensile strength of the concrete, and the constrained specimen will crack. The cracking temperature characterizes the cracking trend of the tested concrete. It is a comprehensive evaluation indicator for factors such as temperature history, elastic modulus, stress relaxation, and tensile strength. The lower the cracking temperature, the smaller the risk of cracking and the smaller the tendency of early thermal cracks. Figure 5 It can be seen that the cracking temperature of concrete specimen 2 is lower than that of concrete specimen 1 by △T2. Concrete specimen 1 cracks at 21℃, and the cracking temperature of concrete specimen 2 after adding microcapsule slow-release material is reduced to near 0℃, which has an excellent effect of inhibiting concrete temperature shrinkage cracking. The cracking stress indicates the ultimate tensile strength of concrete. Figure 5 It can be seen that the stress levels of the two are similar, both around 2.5MPa, indicating that the microcapsule sustained-release material has almost no effect on the ultimate tensile strength of concrete.

[0102] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A microcapsule sustained-release material, characterized in that: The microcapsule sustained-release material comprises a core and a coating layer; the core comprises a porous carbon material and a temperature-suppressing material, and the coating layer is a hot-melt adhesive film.

2. The microcapsule sustained-release material according to claim 1, characterized in that: The mass ratio of the temperature-suppressing material, the porous carbon material and the hot-melt adhesive film is (55-80): (40-50): (3-5); Optionally, the particle size of the microcapsule sustained-release material is 0.05-0.6 mm.

3. The microcapsule sustained-release material according to claim 1, characterized in that: The temperature-inhibiting material includes modified starch; Optionally, the modified starch includes one or more of hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin; Optionally, the modified starch includes hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin; Optionally, the mass ratio of hydroxypropyl distarch phosphate, sodium starch octenyl succinate and yellow dextrin is (10-20): (15-20): (30-40).

4. The microcapsule sustained-release material according to claim 1, characterized in that: The porous carbon material includes one or more of activated carbon, carbon nanotubes, carbon aerogel and biochar; Optionally, the biochar comprises sewage sludge-derived carbon material; Optionally, the method for preparing the sludge-derived carbon material comprises the following steps: sintering the sludge under a protective atmosphere to obtain the sludge-derived carbon material.

5. The microcapsule sustained-release material according to claim 1, characterized in that: The melting point of the hot melt adhesive film is 50-65°C; Optionally, the hot melt adhesive film is a TPU hot melt adhesive film.

6. The method for preparing the microcapsule sustained-release material according to any one of claims 1 to 5, characterized in that: The following steps are involved: The temperature-suppressing material, the porous carbon material and water are mixed and granulated to obtain granules; The granules are mixed with a molten hot melt adhesive film to prepare a microcapsule sustained-release material.

7. The method for preparing the microcapsule sustained-release material according to claim 6, characterized in that: The steps of mixing the temperature-suppressing material, the porous carbon material and water and granulating to obtain granules include: Mixing the temperature-suppressing material and water to obtain a first mixed solution; After heating the first mixed liquid to a target temperature, mixing it with a porous carbon material to obtain a second mixed liquid, and then granulating it to obtain pellets; Optionally, the first mixed liquid has a mass solid content of 25-35%; Optionally, the target temperature is 50-60°C.

8. The method for preparing the microcapsule sustained-release material according to claim 6, characterized in that: The molten hot melt adhesive film is obtained by preheating the hot melt adhesive film; Optionally, the preheating temperature is 90-110°C; Optionally, the rotation speed of mixing the pellets with the molten hot melt adhesive film is 250-350 r / min.

9. Use of the microcapsule sustained-release material according to any one of claims 1 to 5 or the microcapsule sustained-release material prepared by the preparation method according to claims 6 to 8 in controlling temperature shrinkage cracking of concrete.

10. The use according to claim 9, characterized in that: The concrete includes concrete for tunnel lining, concrete for subway corridor side walls or concrete for industrial and civil basement exterior walls.

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