Anti-crack concrete and preparation method thereof

Abstract

The invention belongs to the technical field of concrete, and particularly provides anti-crack concrete and a preparation method thereof. The anti-crack concrete comprises the following components: cement, water, natural sand, broken stone, fly ash, a polycarboxylic acid water reducing agent, polypropylene fibers, montmorillonite and a core-shell anti-ultraviolet agent. The prepared concrete has the advantages of being high in ultraviolet resistance, excellent in crack resistance, high in durability and the like, and is suitable for outdoor scenes such as building outer walls, bridges and roads.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to an anti-cracking concrete and a preparation method thereof. BACKGROUND

[0002] As the most widely used basic material in construction engineering, concrete is widely used in outdoor scenes such as building exterior walls, bridges and roads due to its advantages of wide material sources and stable mechanical properties. However, concrete is prone to degradation of internal cement hydration products when exposed to strong ultraviolet light for a long time, leading to surface powdering, strength reduction, and accelerated corrosion of internal steel bars, which seriously damages the load-bearing capacity and service life of the structure, and brings huge safety hazards and economic losses. Therefore, improving the anti-ultraviolet ability of concrete is of great significance to prolong the service life of buildings in outdoor environments.

[0003] At present, the methods for improving the anti-ultraviolet performance of concrete mainly include coating an anti-ultraviolet coating on the surface of the concrete or adding inorganic nano anti-ultraviolet fillers. However, these methods have certain limitations. The surface coating is easy to wear and peel off, and needs regular maintenance, which increases the later cost. Although the direct addition of inorganic nano fillers can effectively absorb or reflect ultraviolet light, these nano particles are prone to agglomeration in the concrete matrix, which is difficult to disperse uniformly, not only affects the anti-ultraviolet effect, but also may cause cracks due to stress concentration, reducing the mechanical properties of the concrete. Therefore, it is urgent to develop a kind of concrete that can realize the synergistic effect of anti-ultraviolet and anti-cracking, and has uniform component dispersion and excellent long-term stability, to solve the performance degradation problem of existing materials in outdoor complex environments.

[0004] The patent application file with the publication number CN115974467A proposes an anti-ultraviolet and anti-carbonization concrete and a preparation method thereof. The method proposes two lines of defense of "anti-ultraviolet" and "anti-carbonization", and uses benzotriazole, nano TiO2 and modified T-ZnO whiskers to realize the synergistic effect of absorption, reflection and scattering, and covers different wave bands of ultraviolet light. However, the agglomeration risk of nano materials in the concrete system still exists. In addition, the patent application file with the publication number CN119683934A effectively solves the problems of easy agglomeration and uneven dispersion of anti-ultraviolet additives in concrete by pre-mixing bio-based water reducing agent and anti-ultraviolet additives under specific temperature and magnetic field conditions, significantly improving the dispersity. However, this method relies on organic additives for anti-ultraviolet, and the organic components are prone to degradation when exposed to strong ultraviolet light for a long time, which may lead to the attenuation of anti-ultraviolet performance and insufficient long-term durability. SUMMARY

[0005] In view of the above problems, in order to further improve the anti-cracking performance and anti-ultraviolet ability of the anti-cracking concrete, the present application provides an anti-cracking concrete and a preparation method thereof.

[0006] The application provides an anti-cracking concrete, which comprises the following raw materials in parts by weight: cement 35-45 parts, water 18-22 parts, natural sand 45-55 parts, gravel 55-65 parts, fly ash 8-12 parts, polycarboxylic acid water reducing agent 0.15-0.25 parts, polypropylene fiber 0.2-0.4 parts, montmorillonite 0.4-0.6 parts and core-shell anti-ultraviolet agent 1.2-1.8 parts; and the preparation method of the core-shell anti-ultraviolet agent comprises the following steps: The lignin colloidal solution is added into toluene containing tetrabutyl titanate and polyvinyl alcohol, the precipitate is collected by centrifugation after stirring and reaction, and then the precipitate is subjected to acid treatment, washing and placement in a high-humidity environment to obtain the core-shell anti-ultraviolet agent.

[0007] Further, the volume ratio of tetrabutyl titanate to toluene is 1:(8-10).

[0008] Further, the temperature of the acid treatment is 40-60 DEG C.

[0009] Further, the relative humidity of the high-humidity environment is 50-80%.

[0010] Further, the preparation method of the lignin colloidal solution comprises the following steps: The lignin sulfate is uniformly dispersed into dimethyl isosorbide, and deionized water is added under vigorous stirring, and the mixture is continuously stirred to obtain the lignin colloidal solution.

[0011] Further, the volume ratio of dimethyl isosorbide to deionized water is 1:(1.5-2.5).

[0012] Further, the length of the polypropylene fiber is 0.5-2 mm.

[0013] Further, the fineness modulus of the natural sand is 1.8-2.2.

[0014] The application further provides a preparation method of the anti-cracking concrete, which comprises the following steps: S1: dry mixing natural sand, gravel and fly ash to obtain a first mixture; S2: dry mixing polypropylene fiber, montmorillonite and cement to obtain a second mixture; S3: dry mixing the first mixture and the second mixture to obtain a third mixture; S4: dissolving polycarboxylic acid water reducing agent in water, adding core-shell anti-ultraviolet agent and mixing uniformly to obtain a fourth mixture; S5: pouring the fourth mixture into the third mixture for wet mixing to obtain the anti-cracking concrete.

[0015] Further, the dry mixing time is 2-3 min, and the wet mixing time is 3-4 min.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1、The core-shell anti-ultraviolet agent of the present application takes TiO2 as the shell and lignin as the core, and cooperatively constructs an ultraviolet protection system. The TiO2 shell layer is uniformly dispersed in the concrete during the mixing and stirring stage, and forms a first protective barrier by virtue of the high specific surface area of the nanoscale, high-efficiency ultraviolet reflection and scattering ability; during the drying shrinkage process of the concrete, external force can cause the TiO2 shell layer to break, releasing the lignin in the core, and the lignin as a natural ultraviolet absorber can fill the concrete and improve the overall ultraviolet resistance of the concrete, achieving long-term ultraviolet resistance and significantly prolonging the outdoor service life of the concrete.

[0017] 2、The TiO2 shell layer of the core-shell anti-ultraviolet agent prepared in the present application can fill the small pores in the concrete, optimize the internal structure, and improve the compactness; during the drying shrinkage of the concrete, the TiO2 shell layer breaks, transferring internal stress and reducing the generation of fine cracks in the concrete. The broken TiO2 shell layer cooperates with components such as polypropylene fibers, and the three components work together to effectively reduce the probability of crack generation and improve the overall crack resistance.

[0018] 3、The addition of polyvinyl alcohol during the preparation of the TiO2 shell can improve the compatibility of the core-shell anti-ultraviolet agent with other components and reduce the occurrence of agglomeration; the hydroxyl groups in PVA can form hydrogen bonds with the cement hydration products, enhancing the interfacial bonding force with the cement matrix, improving the toughness of the shell layer, avoiding premature rupture of the core-shell structure during preparation, and ensuring the stability of the core-shell structure during preparation and molding. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Carbonation section of the anti-cracking concrete prepared in Example 1 of the present application.

[0020] Figure 2 Carbonation section of the anti-cracking concrete prepared in Example 2 of the present application.

[0021] Figure 3 Carbonation section of the anti-cracking concrete prepared in Example 3 of the present application.

[0022] Figure 4 Carbonation section of the anti-cracking concrete prepared in Control Group 1 of the present application.

[0023] Figure 5 Carbonation section of the anti-cracking concrete prepared in Control Group 2 of the present application. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and beneficial technical effects of the present application clearer, the present application will be further described in detail below in conjunction with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based upon the embodiments in the present application, any other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0025] 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 the present application belongs. The terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] In the case of using "comprising", "having", and "including" in the description herein, it is intended to cover non-exclusive inclusion, unless using the explicit limitation term, such as "only", "consisting of", etc., another component can be added.

[0027] The words "preferably", "more preferably", "particularly preferably", "best" and the like in the present application are used to describe the embodiments of the present application which can provide certain advantages in certain situations. However, other embodiments can also be preferred in the same or other situations. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not useful, nor does it imply that these other embodiments are excluded from the scope of the present application. That is, in the present application, "preferably", "more preferably", "particularly preferably", "best" and the like are only to describe the implementation or embodiment with better effects, but do not constitute a limitation on the protection scope of the present application.

[0028] In the present application, "further", "even further", "in particular" and the like are used to describe purposes and indicate differences in content, but should not be understood as a limitation on the protection scope of the present application.

[0029] In the present application, "at least one" means one or more, such as one, two, and two or more. The meaning of "a plurality of" or "several" is at least two, such as two, three, etc. The meaning of "a plurality of layers" is at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise explicitly specified.

[0030] When a range of values is disclosed, unless otherwise stated, the endpoints of the ranges are included. The disclosure of a range of values includes each and every value and sub-range within the range. Further, ranges of values for materials, such as amounts, are disclosed. Unless otherwise stated, a range includes each and every value and sub-range within the range. In addition, unless otherwise indicated, individual values and sub-ranges within ranges are included.

[0031] Unless specifically stated otherwise, all steps within a process can be performed sequentially or in parallel. For example, the method includes steps (a) and (b), which can mean that the method can include steps (a) followed by (b), or steps (b) followed by (a), etc. Also, the method can include steps (c), which can mean that the method can include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc. The singular form "a", "an", and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a" or "an" means "at least one" or "one or more" unless otherwise indicated.

[0032] In this application, "above" or "below" includes the number itself. For example, 1 or below includes 1.

[0033] In this application, room temperature refers to 0-40℃, including but not limited to 10-40℃, or further 20-30℃.

[0034] The application will be further described by the following examples, but the scope of the application is not limited by the examples.

[0035] When a numerical range is given in the examples, it is understood that, unless otherwise stated in the application, each numerical range has two endpoints and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the application have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise noted, the conditions in the examples were carried out under conventional conditions or manufacturer's recommendations. Unless otherwise noted, all reagents or instruments were conventional products that can be purchased on the market. In addition to the specific methods, devices, materials used in the examples, any method, device and material of the prior art similar or equivalent to the methods, devices and materials described in the examples can also be used to implement the application according to the prior art mastered by those skilled in the art and the description of the application.

[0036] Example 1 The anti-cracking concrete of the embodiment comprises raw materials in the following weights: 40 kg of cement, 20 kg of water, 50 kg of natural sand, 60 kg of gravel, 10 kg of fly ash, 0.2 kg of polycarboxylate superplasticizer, 0.3 kg of polypropylene fiber, 0.5 kg of montmorillonite, and 1.5 kg of core-shell anti-ultraviolet agent; the cement is ordinary portland cement with a mark of 42.5; the natural sand has a fineness modulus of 2.0; the fly ash is selected from secondary fly ash; and the polypropylene fiber has a length of 1 mm.

[0037] The preparation method of the lignin colloidal solution of the embodiment comprises the following steps: 10 g of sulfonated lignin is dissolved in 500 mL of dimethyl isosorbide at 50°C for 30 min under ultrasonic treatment; 1000 mL of deionized water is added under vigorous stirring, and stirring is performed for 20 min to obtain a lignin colloid.

[0038] The preparation method of the core-shell anti-ultraviolet agent of the embodiment comprises the following steps: 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol are added to 450 mL of toluene, and stirring is performed for 1 h to obtain a titanium solution; The lignin colloidal solution is discharged from the nozzle into the titanium solution at a speed of 500 drops per second, and slow stirring is performed for 4 h; the precipitate is collected by centrifugation, transferred to 200 mL of 0.1M nitric acid solution after washing with deionized water, and stirred at 50°C for 2 h; the precipitate is collected by centrifugation, washed with ethanol and deionized water in sequence, and then placed in an environment with a relative humidity of 65%.

[0039] The preparation method of the anti-cracking concrete of the embodiment comprises the following steps: S1: natural sand, gravel, and fly ash are stirred for 2.5 min to obtain a first mixture; S2: polypropylene fiber, montmorillonite, and cement are stirred for 2.5 min to obtain a second mixture; S3: the first mixture and the second mixture are mixed and stirred for 2.5 min to obtain a third mixture; S4: the polycarboxylate superplasticizer is uniformly dissolved in water, and the core-shell anti-ultraviolet agent is added, and stirring is performed for 10 min to ensure that the components are uniformly dispersed in the water to obtain a fourth mixture; S5: the fourth mixture is slowly poured into the stirrer containing the third mixture, and continuous stirring is performed for 3.5 min to obtain the anti-cracking concrete.

[0040] Example 2 The anti-cracking concrete of the embodiment comprises raw materials in the following weights: 35 kg of cement, 18 kg of water, 45 kg of natural sand, 55 kg of gravel, 8 kg of fly ash, 0.15 kg of polycarboxylate superplasticizer, 0.2 kg of polypropylene fiber, 0.4 kg of montmorillonite, and 1.2 kg of core-shell anti-ultraviolet agent; the cement is ordinary portland cement with a mark of 42.5; the natural sand has a fineness modulus of 1.8; the fly ash is selected from secondary fly ash; and the polypropylene fiber has a length of 0.5 mm.

[0041] The preparation method of the lignin colloidal solution of the embodiment comprises the following steps: 10 g of sulfonated lignin is dissolved in 500 mL of dimethyl isosorbide, and ultrasonic treatment is performed at 50 DEG C for 30 min until the lignin is dissolved; 750 mL of deionized water is added under vigorous stirring, and stirring is performed for 20 min to obtain a lignin colloid.

[0042] The preparation method of the core-shell anti-ultraviolet agent of the embodiment comprises the following steps: 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol are added to 400 mL of toluene, and stirring is performed for 1 h to obtain a titanium solution; The lignin colloidal solution is discharged from a nozzle into the titanium solution at a speed of 500 drops per second, and slow stirring is performed for 4 h; the precipitate is collected by centrifugation, transferred to 200 mL of 0.1 M nitric acid solution after washing with deionized water, and stirred at 40 DEG C for 2 h; the precipitate is collected by centrifugation, washed with ethanol and deionized water in sequence, and then placed in an environment with a relative humidity of 50%.

[0043] The preparation method of the anti-cracking concrete of the embodiment comprises the following steps: S1: natural sand, gravel, and fly ash are stirred for 2 min to obtain a first mixture; S2: polypropylene fiber, montmorillonite, and cement are stirred for 2 min to obtain a second mixture; S3: the first mixture and the second mixture are mixed and stirred for 2 min to obtain a third mixture; S4: polycarboxylate superplasticizer is uniformly dissolved in water, and then the core-shell anti-ultraviolet agent is added, and stirring is performed for 10 min to ensure that the components are uniformly dispersed in the water to obtain a fourth mixture; S5: the fourth mixture is slowly poured into a stirrer containing the third mixture, and stirring is continuously performed for 3 min to obtain the anti-cracking concrete.

[0044] Example 3 The anti-cracking concrete of the embodiment comprises raw materials in the following weights: 45 kg of cement, 22 kg of water, 55 kg of natural sand, 65 kg of gravel, 12 kg of fly ash, 0.25 kg of polycarboxylate superplasticizer, 0.4 kg of polypropylene fiber, 0.6 kg of montmorillonite, and 1.8 kg of core-shell anti-ultraviolet agent; the cement is ordinary portland cement with a mark of 42.5; the natural sand has a fineness modulus of 2.2; the fly ash is selected from secondary fly ash; and the polypropylene fiber has a length of 2 mm.

[0045] The preparation method of the lignin colloidal solution of the embodiment comprises the following steps: 10 g of sulfonated lignin is dissolved in 500 mL of dimethyl isosorbide, and ultrasonic treatment is performed at 50°C for 30 min until the lignin is dissolved; 1250 mL of deionized water is added under vigorous stirring, and stirring is performed for 20 min to obtain a lignin colloid.

[0046] The preparation method of the core-shell anti-ultraviolet agent of the embodiment comprises the following steps: 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol are added to 500 mL of toluene, and stirring is performed for 1 h to obtain a titanium solution; The lignin colloidal solution is discharged from the nozzle into the titanium solution at a speed of 500 drops per second, and slow stirring is performed for 4 h; the precipitate is collected by centrifugation, transferred to 200 mL of 0.1M nitric acid solution after washing with deionized water, and stirred at 60°C for 2 h; the precipitate is collected by centrifugation, washed with ethanol and deionized water in sequence, and then placed in an environment with a relative humidity of 80%.

[0047] The preparation method of the anti-cracking concrete of the embodiment comprises the following steps: S1: natural sand, gravel, and fly ash are stirred for 3 min to obtain a first mixture; S2: polypropylene fiber, montmorillonite, and cement are stirred for 3 min to obtain a second mixture; S3: the first mixture and the second mixture are mixed and stirred for 3 min to obtain a third mixture; S4: the polycarboxylate superplasticizer is uniformly dissolved in water, and the core-shell anti-ultraviolet agent is added, and stirring is performed for 10 min to ensure that the components are uniformly dispersed in the water to obtain a fourth mixture; S5: the fourth mixture is slowly poured into the stirrer containing the third mixture, and continuous stirring is performed for 4 min to obtain the anti-cracking concrete.

[0048] Control group 1 The anti-cracking concrete of the control group comprises the following raw materials by weight: 40 kg of cement, 20 kg of water, 50 kg of natural sand, 60 kg of gravel, 10 kg of fly ash, 0.2 kg of polycarboxylate superplasticizer, 0.3 kg of polypropylene fiber, and 0.5 kg of montmorillonite; the cement is ordinary portland cement with a mark of 42.5; the natural sand has a fineness modulus of 2.0; the fly ash is selected from secondary fly ash; and the polypropylene fiber has a length of 1 mm.

[0049] The preparation method of the anti-cracking concrete of the control group comprises the following steps: S1: stirring the natural sand, the gravel, and the fly ash for 2.5 min to obtain a first mixture; S2: stirring the polypropylene fiber, the montmorillonite, and the cement for 2.5 min to obtain a second mixture; S3: mixing the first mixture and the second mixture and stirring for 2.5 min to obtain a third mixture; S4: uniformly dissolving the polycarboxylate superplasticizer in the water to obtain a fourth mixture; S5: slowly pouring the fourth mixture into the stirrer containing the third mixture, and continuously stirring for 3.5 min to obtain the anti-cracking concrete.

[0050] Control group 2 The anti-cracking concrete of the control group comprises the following raw materials by weight: 40 kg of cement, 20 kg of water, 50 kg of natural sand, 60 kg of gravel, 10 kg of fly ash, 0.2 kg of polycarboxylate superplasticizer, 0.3 kg of polypropylene fiber, 0.5 kg of montmorillonite, and 1.5 kg of core-shell anti-ultraviolet agent; the cement is ordinary portland cement with a mark of 42.5; the natural sand has a fineness modulus of 2.0; the fly ash is selected from secondary fly ash; and the polypropylene fiber has a length of 1 mm.

[0051] The preparation method of the core-shell anti-ultraviolet agent of the control group comprises the following steps: adding 50 mL of tetrabutyl titanate and 1 g of polyvinyl alcohol into 450 mL of toluene, stirring for 1 h to obtain a titanium solution; slowly stirring for 4 h while deionized water is discharged from a nozzle into the titanium solution at a speed of 500 drops per second, centrifuging to collect the precipitate, transferring the precipitate to 200 mL of 0.1 M nitric acid solution after washing with deionized water, stirring at 50°C for 2 h, centrifuging to collect, sequentially washing with ethanol and deionized water, and then placing in a 65% relative humidity environment.

[0052] The preparation method of the anti-cracking concrete of the control group comprises the following steps: S1: stirring the natural sand, the gravel, and the fly ash for 2.5 min to obtain a first mixture; S2: Stir the polypropylene fiber, montmorillonite and cement for 2.5 min to obtain a second mixture; S3: Mix the first mixture and the second mixture and stir for 2.5 min to obtain a third mixture; S4: Dissolve the polycarboxylic acid water reducer in water uniformly, then add the core-shell anti-ultraviolet agent, stir for 10 min to ensure that each component is uniformly dispersed in water to obtain a fourth mixture; S5: Slowly pour the fourth mixture into the stirrer containing the third mixture, continue to stir for 3.5 min to obtain the anti-cracking concrete.

[0053] Performance test 1. Compressive strength test: The anti-cracking concrete prepared in Examples 1-3 and Control Groups 1-2 was tested for compressive strength according to the “GB / T50081-2019 Standard for Testing Methods for Physical and Mechanical Properties of Concrete”. Observe whether cracks are generated on the surface of each sample and record the length of the cracks; the test sample is a 100mm x 100mm x 100mm specimen.

[0054] 2. Flexural strength test: The anti-cracking concrete prepared in Examples 1-3 and Control Groups 1-2 was tested for flexural strength according to the “GB / T50081-2019 Standard for Testing Methods for Physical and Mechanical Properties of Concrete”; the test sample is a 100mm x 100mm x 400mm specimen.

[0055] 3. Anti-ultraviolet test: The anti-cracking concrete prepared in Examples 1-3 and Control Groups 1-2 was placed in an ultraviolet aging test box for 10 days to simulate an ultraviolet irradiation environment. The carbonation test was performed on the anti-cracking concrete prepared in Examples 1-3 and Control Groups 1-2 according to the “GB / T50082-2024 Standard for Testing Methods for Long-term Performance and Durability of Ordinary Concrete”. The carbonation depth after ultraviolet aging was used to characterize the anti-ultraviolet ability.

[0056] Table 1 Performance test results of anti-cracking concrete Analysis of Examples 1-3 and Control Groups 1-2 and combination Figures 1-5As can be seen from the test data in Table 1, the anti-cracking concrete prepared in the application has excellent mechanical properties, anti-UV aging performance and anti-cracking performance. Compared with Examples 1-3, the anti-cracking concrete of Control Group 1 has no core-shell anti-UV agent added, and the compressive strength and flexural strength of the anti-cracking concrete are significantly reduced, and the carbonation depth is also greater; indicating that the lack of core-shell anti-UV agent synergistic protection, the durability and anti-cracking of the concrete are reduced. Compared with Examples 1-3, the core-shell anti-UV agent of Control Group 2 does not use lignin colloid, and only deionized water is used instead, and the performance is better than that of Control Group 1, but it is still significantly worse than that of Examples 1-3. This shows that the simple TiO2 shell cannot realize the intelligent release and long-acting protection function of the core-shell structure under stress, and verifies the role of lignin in realizing long-term anti-UV. In summary, the anti-cracking concrete prepared in the application improves the mechanical properties and anti-UV stability of the concrete through the structural design of the core-shell anti-UV agent and the synergistic effect of the components.

[0057] Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A crack-resistant concrete, characterized in that, 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: 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.

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

3. The crack-resistant concrete according to claim 1, characterized in that: The acid treatment temperature is 40-60℃.

4. The crack-resistant concrete according to claim 1, characterized in that: 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: Dissolve the polycarboxylate superplasticizer in water, add the core-shell UV stabilizer, and mix thoroughly to obtain the fourth mixture; 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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