A crack-resistant concrete and its preparation method

Abstract

This application belongs to the field of concrete technology, specifically providing a crack-resistant concrete and its preparation method. The crack-resistant concrete comprises the following components: cement, water, natural sand, crushed stone, fly ash, polycarboxylate superplasticizer, polypropylene fiber, montmorillonite, and a core-shell UV stabilizer. The concrete prepared by this application has advantages such as strong UV resistance, excellent crack resistance, and high durability, making it suitable for outdoor applications such as building exterior walls, bridges, and roads.

Description

Technical Field

[0001] This application belongs to the field of concrete technology, and in particular relates to a crack-resistant concrete and its preparation method. Background Technology

[0002] Concrete, as the most widely used basic material in construction engineering, is extensively used in outdoor applications such as building exteriors, bridges, and roads due to its wide availability and stable mechanical properties. However, long-term exposure to strong ultraviolet radiation can easily cause degradation of cement hydration products, leading to surface powdering, reduced strength, and accelerated corrosion of internal reinforcing steel. This severely impairs the load-bearing capacity and service life of the structure, resulting in significant safety hazards and economic losses. Therefore, improving the UV resistance of concrete is of great significance for extending the service life of buildings in outdoor environments.

[0003] Currently, the main methods for improving the UV resistance of concrete are coating the concrete surface with UV-resistant coatings or adding inorganic nano-UV-resistant fillers. However, these methods have certain limitations. Surface coatings are prone to wear and peeling, and require regular maintenance, increasing long-term costs. While directly adding inorganic nano-fillers can effectively absorb or reflect UV rays, these nanoparticles are prone to agglomeration in the concrete matrix, making uniform dispersion difficult. This not only affects the UV resistance but may also cause cracks due to stress concentration, reducing the mechanical properties of the concrete. Therefore, there is an urgent need to develop a type of concrete that can achieve synergistic effects in UV resistance and crack resistance, with uniform component dispersion and excellent long-term stability, to solve the problem of performance degradation of existing materials in complex outdoor environments.

[0004] Patent application CN115974467A discloses a UV-resistant and carbonation-resistant concrete and its preparation method. This method proposes two lines of defense: UV resistance and carbonation resistance. It employs a composite of benzotriazole with nano-TiO2 and modified T-ZnO whiskers to achieve a synergistic effect of absorption, reflection, and scattering, covering different wavelengths of ultraviolet radiation. However, it still does not solve the risk of agglomeration of nanomaterials in the concrete system. In addition, patent application CN119683934A pre-mixes a bio-based water-reducing agent with a UV-resistant additive under specific temperature and magnetic field conditions, effectively solving the problem of easy agglomeration and uneven dispersion of UV-resistant additives in concrete, significantly improving its dispersibility. However, this method relies on organic additives for UV resistance; long-term exposure to strong ultraviolet radiation can cause degradation of organic components, leading to a decrease in UV resistance and insufficient long-term durability. Summary of the Invention

[0005] To address the aforementioned issues and further improve the crack resistance and UV resistance of crack-resistant concrete, this application provides a crack-resistant concrete and its preparation method.

[0006] This application first provides a crack-resistant concrete, comprising the following raw materials in parts by weight: 35-45 parts cement, 18-22 parts water, 45-55 parts natural sand, 55-65 parts crushed stone, 8-12 parts fly ash, 0.15-0.25 parts polycarboxylate superplasticizer, 0.2-0.4 parts polypropylene fiber, 0.4-0.6 parts montmorillonite, and 1.2-1.8 parts core-shell UV stabilizer; the preparation method of the core-shell UV stabilizer includes the following steps:

[0007] The lignin colloidal solution was added to toluene containing tetrabutyl titanate and polyvinyl alcohol. After stirring and reacting, the precipitate was collected by centrifugation, treated with acid, washed, and then placed in a high-humidity environment to obtain the final product.

[0008] Furthermore, the volume ratio of tetrabutyl titanate to toluene is 1:(8-10).

[0009] Furthermore, the acid treatment temperature is 40-60°C.

[0010] Furthermore, the relative humidity of the high-humidity environment is 50-80%.

[0011] Furthermore, the preparation method of the lignin colloidal solution includes the following steps:

[0012] Sulfate lignin is uniformly dispersed in dimethyl isosorbide, and deionized water is added under vigorous stirring. The mixture is stirred continuously to obtain the final product.

[0013] Furthermore, the volume ratio of dimethyl isosorbide to deionized water is 1:(1.5-2.5).

[0014] Furthermore, the length of the polypropylene fiber is 0.5-2 mm.

[0015] Furthermore, the fineness modulus of the natural sand is 1.8-2.2.

[0016] This application also provides a method for preparing crack-resistant concrete, comprising the following steps:

[0017] S1: Dry-mix natural sand, gravel, and fly ash to obtain the first mixture;

[0018] S2: Dry-mix polypropylene fiber, montmorillonite, and cement to obtain a second mixture;

[0019] S3: Dry-mix the first mixture and the second mixture to obtain the third mixture;

[0020] S4: Dissolve the polycarboxylate superplasticizer in water, add the core-shell UV stabilizer, and mix thoroughly to obtain the fourth mixture;

[0021] S5: Pour the fourth mixture into the third mixture and mix wet to obtain the final product.

[0022] Furthermore, the dry mixing time is 2-3 minutes, and the wet mixing time is 3-4 minutes.

[0023] Compared with the prior art, this application has the following beneficial effects:

[0024] 1. The core-shell UV stabilizer of this application uses TiO2 as the shell and lignin as the core to synergistically construct a UV protection system. The TiO2 shell is completely and uniformly dispersed inside the concrete during the concrete mixing stage. With its high specific surface area at the nanoscale, it has an efficient ability to reflect and scatter ultraviolet rays, forming the first line of defense. During the drying and shrinkage process of the concrete, external forces can cause the TiO2 shell to crack, releasing the lignin core. As a natural ultraviolet absorber, lignin can fill the interior of the concrete, improve the overall UV resistance of the concrete, achieve long-term UV protection, and significantly extend the outdoor service life of the concrete.

[0025] 2. The TiO2 shell of the core-shell UV stabilizer prepared in this application can fill the tiny pores in concrete, optimize the internal structure, and improve the density. During concrete drying shrinkage, the TiO2 shell cracks, transferring internal stress and reducing the generation of micro-cracks inside the concrete. The cracked TiO2 shell synergizes with components such as polypropylene fibers, and the three work together to effectively reduce the probability of crack formation and improve the overall crack resistance.

[0026] 3. Adding polyvinyl alcohol during the preparation of TiO2 shell can improve the compatibility of the core-shell UV stabilizer with other components and reduce the occurrence of agglomeration. The hydroxyl groups rich in PVA can form hydrogen bonds with cement hydration products, enhance the interfacial bonding force with the cement matrix, and improve the toughness of the shell layer. This prevents premature breakage of the core-shell structure during the preparation process and ensures the stability of the core-shell structure during the preparation and molding stages. Attached Figure Description

[0027] Figure 1 The carbonation cross-section of the crack-resistant concrete prepared in Example 1 of this application is shown.

[0028] Figure 2 The carbonation cross-section of the crack-resistant concrete prepared in Example 2 of this application is shown.

[0029] Figure 3 The carbonation cross-section of the crack-resistant concrete prepared in Example 3 of this application is shown.

[0030] Figure 4 The carbonation cross-section of the crack-resistant concrete prepared in control group 1 of this application is shown.

[0031] Figure 5The carbonation cross-section of the crack-resistant concrete prepared in control group 2 of this application is shown. Detailed Implementation

[0032] To make the inventive objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments described herein. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0035] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0036] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0037] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0038] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0039] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0040] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0041] In this application, room temperature refers to 0~40℃, including but not limited to 10~40℃, or further to 20~30℃.

[0042] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0043] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0044] Example 1

[0045] The crack-resistant concrete of this embodiment comprises the following raw materials by weight: 40kg cement, 20kg water, 50kg natural sand, 60kg crushed stone, 10kg fly ash, 0.2kg polycarboxylate superplasticizer, 0.3kg polypropylene fiber, 0.5kg montmorillonite, and 1.5kg core-shell UV stabilizer; the cement is ordinary Portland cement with a grade of 42.5; the fineness modulus of the natural sand is 2.0; the fly ash is grade II fly ash; and the polypropylene fiber has a length of 1mm.

[0046] The method for preparing the lignin colloidal solution in this embodiment includes the following steps:

[0047] 10g of sulfate lignin was dissolved in 500mL of dimethyl isosorbide and sonicated at 50℃ for 30min until dissolved; 1000mL of deionized water was added under vigorous stirring and stirred for 20min to obtain lignin colloid.

[0048] The preparation method of the core-shell UV stabilizer in this embodiment includes the following steps:

[0049] Add 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol to 450 mL of toluene and stir for 1 h to obtain a titanium solution.

[0050] The lignin colloidal solution was discharged from the nozzle into the titanium solution at a rate of 500 drops / second, stirred slowly for 4 hours, centrifuged to collect the precipitate, washed with deionized water, transferred to 200 mL of 0.1 M nitric acid solution, stirred at 50 °C for 2 hours, centrifuged to collect the precipitate, washed successively with ethanol and deionized water, and then placed in an environment with 65% relative humidity.

[0051] The method for preparing crack-resistant concrete in this embodiment includes the following steps:

[0052] S1: Take natural sand, crushed stone, and fly ash and mix for 2.5 minutes to obtain the first mixture;

[0053] S2: Take polypropylene fiber, montmorillonite and cement and mix for 2.5 min to obtain the second mixture;

[0054] S3: Mix the first mixture and the second mixture and stir for 2.5 minutes to obtain the third mixture;

[0055] S4: Dissolve the polycarboxylate superplasticizer evenly in water, then add the core-shell UV stabilizer, stir for 10 minutes to ensure that each component is evenly dispersed in water, and obtain the fourth mixture;

[0056] S5: Slowly pour the fourth mixture into the mixer containing the third mixture and continue mixing for 3.5 minutes to obtain crack-resistant concrete.

[0057] Example 2

[0058] The crack-resistant concrete of this embodiment comprises the following raw materials by weight: 35kg cement, 18kg water, 45kg natural sand, 55kg crushed stone, 8kg fly ash, 0.15kg polycarboxylate superplasticizer, 0.2kg polypropylene fiber, 0.4kg montmorillonite, and 1.2kg core-shell UV stabilizer; the cement is ordinary Portland cement with a grade of 42.5; the fineness modulus of the natural sand is 1.8; the fly ash is grade II fly ash; and the polypropylene fiber has a length of 0.5mm.

[0059] The method for preparing the lignin colloidal solution in this embodiment includes the following steps:

[0060] 10g of sulfate lignin was dissolved in 500mL of dimethyl isosorbide and sonicated at 50℃ for 30min until dissolved; 750mL of deionized water was added under vigorous stirring and stirred for 20min to obtain lignin colloid.

[0061] The preparation method of the core-shell UV stabilizer in this embodiment includes the following steps:

[0062] Add 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol to 400 mL of toluene and stir for 1 h to obtain a titanium solution.

[0063] The lignin colloidal solution was discharged from the nozzle into the titanium solution at a rate of 500 drops / second, stirred slowly for 4 hours, centrifuged to collect the precipitate, washed with deionized water, transferred to 200 mL of 0.1 M nitric acid solution, stirred at 40 °C for 2 hours, centrifuged to collect the precipitate, washed successively with ethanol and deionized water, and then placed in an environment with 50% relative humidity.

[0064] The method for preparing crack-resistant concrete in this embodiment includes the following steps:

[0065] S1: Take natural sand, crushed stone and fly ash and stir for 2 minutes to obtain the first mixture;

[0066] S2: Take polypropylene fiber, montmorillonite and cement and mix for 2 minutes to obtain the second mixture;

[0067] S3: Mix the first mixture and the second mixture and stir for 2 minutes to obtain the third mixture;

[0068] S4: Dissolve the polycarboxylate superplasticizer evenly in water, then add the core-shell UV stabilizer, stir for 10 minutes to ensure that each component is evenly dispersed in water, and obtain the fourth mixture;

[0069] S5: Slowly pour the fourth mixture into the mixer containing the third mixture and continue mixing for 3 minutes to obtain crack-resistant concrete.

[0070] Example 3

[0071] The crack-resistant concrete of this embodiment comprises the following raw materials by weight: 45kg cement, 22kg water, 55kg natural sand, 65kg crushed stone, 12kg fly ash, 0.25kg polycarboxylate superplasticizer, 0.4kg polypropylene fiber, 0.6kg montmorillonite, and 1.8kg core-shell UV stabilizer; the cement is ordinary Portland cement with a grade of 42.5; the fineness modulus of the natural sand is 2.2; the fly ash is grade II fly ash; and the polypropylene fiber has a length of 2mm.

[0072] The method for preparing the lignin colloidal solution in this embodiment includes the following steps:

[0073] 10g of sulfate lignin was dissolved in 500mL of dimethyl isosorbide and sonicated at 50℃ for 30min until dissolved; 1250mL of deionized water was added under vigorous stirring and stirred for 20min to obtain lignin colloid.

[0074] The preparation method of the core-shell UV stabilizer in this embodiment includes the following steps:

[0075] Add 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol to 500 mL of toluene and stir for 1 h to obtain a titanium solution.

[0076] The lignin colloidal solution was discharged from the nozzle into the titanium solution at a rate of 500 drops / second, stirred slowly for 4 hours, centrifuged to collect the precipitate, washed with deionized water, transferred to 200 mL of 0.1 M nitric acid solution, stirred at 60 °C for 2 hours, centrifuged to collect the precipitate, washed successively with ethanol and deionized water, and then placed in an environment with 80% relative humidity.

[0077] The method for preparing crack-resistant concrete in this embodiment includes the following steps:

[0078] S1: Take natural sand, gravel, and fly ash and mix for 3 minutes to obtain the first mixture;

[0079] S2: Take polypropylene fiber, montmorillonite and cement and mix for 3 minutes to obtain the second mixture;

[0080] S3: Mix the first mixture and the second mixture and stir for 3 minutes to obtain the third mixture;

[0081] S4: Dissolve the polycarboxylate superplasticizer evenly in water, then add the core-shell UV stabilizer, stir for 10 minutes to ensure that each component is evenly dispersed in water, and obtain the fourth mixture;

[0082] S5: Slowly pour the fourth mixture into the mixer containing the third mixture and continue mixing for 4 minutes to obtain crack-resistant concrete.

[0083] Control group 1

[0084] The crack-resistant concrete in this control group comprises the following raw materials by weight: 40 kg cement, 20 kg water, 50 kg natural sand, 60 kg crushed stone, 10 kg fly ash, 0.2 kg polycarboxylate superplasticizer, 0.3 kg polypropylene fiber, and 0.5 kg montmorillonite. The cement used is ordinary Portland cement with a grade of 42.5. The fineness modulus of the natural sand is 2.0. The fly ash used is grade II fly ash. The polypropylene fiber has a length of 1 mm.

[0085] The preparation method of the crack-resistant concrete in this control group includes the following steps:

[0086] S1: Take natural sand, crushed stone, and fly ash and mix for 2.5 minutes to obtain the first mixture;

[0087] S2: Take polypropylene fiber, montmorillonite and cement and mix for 2.5 min to obtain the second mixture;

[0088] S3: Mix the first mixture and the second mixture and stir for 2.5 minutes to obtain the third mixture;

[0089] S4: Dissolve the polycarboxylate superplasticizer evenly in water to obtain the fourth mixture;

[0090] S5: Slowly pour the fourth mixture into the mixer containing the third mixture and continue mixing for 3.5 minutes to obtain crack-resistant concrete.

[0091] Control group 2

[0092] The crack-resistant concrete in this control group comprises the following raw materials by weight: 40 kg cement, 20 kg water, 50 kg natural sand, 60 kg crushed stone, 10 kg fly ash, 0.2 kg polycarboxylate superplasticizer, 0.3 kg polypropylene fiber, 0.5 kg montmorillonite, and 1.5 kg core-shell UV stabilizer; the cement used is ordinary Portland cement with a grade of 42.5; the fineness modulus of the natural sand is 2.0; the fly ash used is grade II fly ash; and the polypropylene fiber has a length of 1 mm.

[0093] The preparation method of the core-shell UV stabilizer in this control group includes the following steps:

[0094] Add 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol to 450 mL of toluene and stir for 1 h to obtain a titanium solution.

[0095] Deionized water was discharged from the nozzle into the titanium solution at a rate of 500 drops / second. The mixture was stirred slowly for 4 hours, and the precipitate was collected by centrifugation. After washing with deionized water, the precipitate was transferred to 200 mL of 0.1 M nitric acid solution, stirred at 50 °C for 2 hours, collected by centrifugation, washed successively with ethanol and deionized water, and then placed in an environment with 65% relative humidity.

[0096] The preparation method of the crack-resistant concrete in this control group includes the following steps:

[0097] S1: Take natural sand, crushed stone, and fly ash and mix for 2.5 minutes to obtain the first mixture;

[0098] S2: Take polypropylene fiber, montmorillonite and cement and mix for 2.5 min to obtain the second mixture;

[0099] S3: Mix the first mixture and the second mixture and stir for 2.5 minutes to obtain the third mixture;

[0100] S4: Dissolve the polycarboxylate superplasticizer evenly in water, then add the core-shell UV stabilizer, stir for 10 minutes to ensure that each component is evenly dispersed in water, and obtain the fourth mixture;

[0101] S5: Slowly pour the fourth mixture into the mixer containing the third mixture and continue mixing for 3.5 minutes to obtain crack-resistant concrete.

[0102] Performance testing

[0103] 1. Compressive strength test: The compressive strength of the crack-resistant concrete prepared in Examples 1-3 and Control Groups 1-2 was tested in accordance with the "GB / T50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete". The surface of each sample was observed to see if cracks were generated and the length of the cracks was recorded. The test sample was a 100mm×100mm×100mm specimen.

[0104] 2. Flexural strength test: The flexural strength of the crack-resistant concrete prepared in Examples 1-3 and Control Groups 1-2 was tested in accordance with the "GB / T50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete"; the test sample was a 100mm×100mm×400mm specimen.

[0105] 3. UV resistance test: A UV aging test chamber was used to simulate the UV irradiation environment. The crack-resistant concrete prepared in Examples 1-3 and Control Group 1-2 was placed in the UV aging test chamber and kept for 10 days. Carbonation test was carried out on the crack-resistant concrete prepared in Examples 1-3 and Control Group 1-2 in accordance with the "GB / T50082-2024 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". The carbonation depth after UV aging was used to characterize the UV resistance.

[0106] Table 1 Performance test results of crack-resistant concrete

[0107]

[0108] Analysis of Examples 1-3 and Control Groups 1-2 and in combination Figure 1-5As can be seen from the test data in Table 1, the crack-resistant concrete prepared in this application simultaneously possesses excellent mechanical properties, UV aging resistance, and crack resistance. Compared with Examples 1-3, Control Group 1, which did not add a core-shell UV stabilizer, showed significantly reduced compressive and flexural strengths and a greater carbonation depth; this indicates a lack of synergistic protection from the core-shell UV stabilizer, leading to decreased durability and crack resistance. Compared with Examples 1-3, Control Group 2, which used deionized water instead of lignin colloid in its core-shell UV stabilizer, exhibited better performance in all aspects than Control Group 1, but was still significantly inferior to Examples 1-3. This demonstrates that a simple TiO2 shell cannot achieve the intelligent release and long-term protection function of the core-shell structure under stress, verifying the role of lignin in achieving long-term UV resistance. In summary, the crack-resistant concrete prepared in this application improves the mechanical properties and UV stability of concrete through the structural design of the core-shell UV stabilizer and the synergistic effect of its components.

[0109] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A crack-resistant concrete, characterized by, The raw materials include the following parts by weight: 35-45 parts cement, 18-22 parts water, 45-55 parts natural sand, 55-65 parts crushed stone, 8-12 parts fly ash, 0.15-0.25 parts polycarboxylate superplasticizer, 0.2-0.4 parts polypropylene fiber, 0.4-0.6 parts montmorillonite, and 1.2-1.8 parts core-shell UV stabilizer. The preparation method of the core-shell UV stabilizer includes the following steps: adding a lignin colloidal solution to toluene containing tetrabutyl titanate and polyvinyl alcohol, stirring and reacting, centrifuging to collect the precipitate, and then treating it with acid, washing it, and placing it in a high-humidity environment to obtain the final product.

2. The anti-cracking concrete according to claim 1, characterized in that: The volume ratio of tetrabutyl titanate to toluene is 1:(8-10).

3. The anti-cracking concrete according to claim 1, wherein: The acid treatment temperature is 40-60℃.

4. The anti-cracking concrete according to claim 1, wherein: The relative humidity of the high-humidity environment is 50-80%.

5. The crack-resistant concrete according to claim 1, characterized in that: The preparation method of the lignin colloidal solution includes the following steps: Sulfate lignin is uniformly dispersed in dimethyl isosorbide, and deionized water is added under vigorous stirring. The mixture is stirred continuously to obtain the final product.

6. The crack-resistant concrete according to claim 5, characterized in that: The volume ratio of dimethyl isosorbide to deionized water is 1:(1.5-2.5).

7. The crack-resistant concrete according to claim 1, characterized in that: The polypropylene fiber has a length of 0.5-2 mm.

8. The crack-resistant concrete according to claim 1, characterized in that: The fineness modulus of the natural sand is 1.8-2.

2.

9. A method for preparing crack-resistant concrete, characterized in that, Includes the following steps: S1: Dry-mix natural sand, gravel, and fly ash to obtain the first mixture; S2: Dry-mix polypropylene fiber, montmorillonite, and cement to obtain a second mixture; S3: Dry-mix the first mixture and the second mixture to obtain the third mixture; S4: After dissolving the polycarboxylate superplasticizer in water, add the core-shell UV stabilizer and mix evenly to obtain the fourth mixture; the preparation method of the core-shell UV stabilizer includes the following steps: adding the lignin colloidal solution to toluene containing tetrabutyl titanate and polyvinyl alcohol, stirring and reacting, centrifuging to collect the precipitate, and then placing it in a high-humidity environment after acid treatment and washing to obtain the final product; S5: Pour the fourth mixture into the third mixture and mix wet to obtain the final product.

10. The method for preparing crack-resistant concrete according to claim 9, characterized in that: The dry mixing time is 2-3 minutes, and the wet mixing time is 3-4 minutes.

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