Self-repairing concrete pier and preparation method thereof

Abstract

The application relates to the field of concrete, and particularly discloses a self-repairing concrete pier and a preparation method thereof; the self-repairing concrete pier comprises concrete, a self-repairing material and protective paint, the self-repairing material comprises a fiber net and a composite repair agent, raw materials of the composite repair agent comprise a repair agent and a mesoporous silica ball for loading the repair agent, the mesoporous silica ball loaded with the repair agent is coated with an encapsulating agent on the surface; the repair agent comprises triethanolamine and aspartic acid; and the encapsulating agent comprises chitosan and silica sol; the fiber net and the composite repair agent are used to synergistically enhance the anti-cracking and anti-impact performance of the concrete, the mesoporous silica ball is used to load the repair agent, and the self-repairing performance of the concrete is realized to be persistent.

Description

Technical Field

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

[0002] Traditional concrete bollards are widely used in highway and urban road environments, primarily for separating lanes, preventing vehicles from crossing boundaries, or protecting pedestrian safety. However, traditional concrete bollards are prone to breakage when subjected to high-speed impacts, failing to effectively absorb and disperse impact forces, leading to structural damage or even complete failure. In recent years, with the increase in traffic volume and vehicle speed, higher requirements have been placed on the impact resistance and durability of concrete bollards.

[0003] Currently, the industry mainly addresses the impact resistance issue of concrete piers by increasing concrete reinforcement or using ultra-high performance concrete (UHPC). However, steel corrosion can exacerbate concrete cracking, resulting in insufficient long-term durability. Summary of the Invention

[0004] To address the shortcomings of existing concrete, this application provides a self-healing concrete pier and its preparation method.

[0005] Firstly, this application provides a self-healing concrete pier, employing the following technical solution: A self-healing concrete pier includes concrete, a self-healing material, and a protective coating. The self-healing material includes a fiber mesh and a composite repair agent. The composite repair agent consists of a repair agent and mesoporous silica spheres for loading the repair agent. The surface of the mesoporous silica spheres loaded with the repair agent is coated with an encapsulating agent. The repair agent includes triethanolamine and aspartic acid. The encapsulating agent includes chitosan and silica sol.

[0006] By adopting the above technical solution, the use of fiber mesh covering the concrete surface can improve the tensile strength of the concrete. The crystals and gels generated during concrete hydration, as well as the cement paste, can fill the fiber mesh, achieving a strong mechanical bond and promoting the integration of the fiber mesh with the concrete matrix. The fiber mesh forms a continuous three-dimensional network inside the concrete. When the pier is subjected to impact or compression, the concentrated stress is quickly dispersed to a wider area by the fiber mesh, avoiding local stress overload, reducing large-area cracking of the concrete, inhibiting the continued extension and propagation of microcracks, and improving the impact and bending resistance of the concrete pier. At the same time, the outermost layer of the concrete, coated with a protective coating, can prevent the intrusion of moisture and corrosive media, preventing foreign substances from causing cracks in the concrete.

[0007] The use of mesoporous silica spheres to load the repair agent serves two purposes. First, as rigid particles, they enhance the internal strength of concrete and consume crack propagation energy. Second, the mesoporous silica spheres utilize their internal pores to adsorb triethanolamine and aspartic acid. The hydroxyl and tertiary amine groups in the triethanolamine molecule, as well as the amino and carboxyl groups in the aspartic acid molecule, can form strong hydrogen bonds with the silanol groups contained in the mesoporous silica spheres, resulting in electrostatic adsorption. Combined with an encapsulating agent, the repair agent is firmly sealed within the silica pores, reducing premature leakage of the repair agent during mixing and settling stages, and improving the durability of the concrete's self-healing performance.

[0008] When concrete is subjected to external impact or cracks are generated, the tensile force of the cracks and the impact stress can destroy the encapsulation effect of the mesoporous silica spheres, which can promote the release of the repair agents triethanolamine and aspartic acid. Triethanolamine and aspartic acid can then directly react with calcium ions in the concrete to form calcium crystal precipitates, which directly fill the exposed cracks and seal them, thereby restoring the density and strength of the concrete and achieving self-healing performance.

[0009] Chitosan and silica sol are used to double-encapsulate mesoporous silica spheres. The inner layer uses chitosan to form a film that prevents premature leakage of the repair agent, while the outer layer of silica sol generates a gel in the concrete system through a pozzolanic effect, which enhances the compatibility of the mesoporous silica spheres with the concrete system. This achieves both sealing and volume enhancement effects, thereby improving the overall density and self-healing performance of the concrete pier.

[0010] Preferably, the fiber mesh has a pore size of 200-400 μm, and the mesoporous silica spheres have a particle size of 300-500 μm.

[0011] By adopting the above technical solution, the fiber mesh laid on the concrete surface, with a pore size of 200-400μm, effectively limits the crack opening width. Simultaneously, it physically confines the mesoporous silica spheres carrying the repair agent within the concrete system. When subjected to external impact, it also promotes the timely release of the repair agent from the microspheres, achieving a self-healing effect. The pore size of the fiber mesh is smaller than the particle size of the mesoporous silica spheres, which can largely trap the mesoporous silica spheres carrying the repair agent, reducing the premature damage caused by microsphere migration to the concrete pier surface and improving the durability of the concrete's self-healing performance.

[0012] Preferably, the mesoporous silica spheres are pre-aminated and then loaded with a repair agent, comprising the following specific steps: dissolving the mesoporous silica spheres in anhydrous ethanol, adding aminosilane and mixing, stirring and centrifuging, drying to obtain aminated mesoporous silica spheres, then mixing the aminated mesoporous silica spheres, the repair agent and ethanol, stirring evenly, centrifuging, vacuum drying to obtain mesoporous silica microspheres loaded with the repair agent, and then coating the mesoporous silica microspheres loaded with the repair agent with an encapsulating agent to complete the process.

[0013] By adopting the above technical solution, the mesoporous silica spheres are modified with aminosilane in advance, and a large number of amino groups are firmly grafted onto the inner wall and outer surface of the microspheres, increasing the adsorption sites of the micropores, promoting the repair agent to be firmly loaded inside the mesoporous silica microspheres, increasing the loading capacity of the mesoporous silica microspheres, and thus improving the self-healing performance of concrete.

[0014] Preferably, the mass ratio of the mesoporous silica spheres to aminosilane and the repair agent is 1:(1-1.5):(0.5-0.8).

[0015] Preferably, the mesoporous silica microspheres loaded with the repair agent are first coated with chitosan and then coated with silica sol.

[0016] By adopting the above technical solution, the chitosan coating first forms a tough organic film that can absorb the internal stress generated by the drying shrinkage of the silica sol, thus inhibiting the cracking and peeling of the outer inorganic shell. The silica sol coating on the outer layer effectively blocks calcium and hydroxide ions from entering the pores, slowing down the degradation rate of the chitosan film. Simultaneously, it enhances the strength of the mesoporous silica microspheres loaded with the repair agent, preventing premature release of the repair agent and improving the durability of the stone pier's self-healing performance.

[0017] Preferably, the protective coating comprises the following raw materials in parts by weight: 20-35 parts of amino-terminated polyether, 20-35 parts of isocyanate, 25-40 parts of epoxy silicone oil, 1-3 parts of diamino diglycidyl ether, and 10-25 parts of polyether polyol.

[0018] Preferably, the method for preparing the protective coating includes the following specific steps: Under the protection of nitrogen, terminal epoxy silicone oil is dropped into terminal amino polyether and heated to react. Then, diamino diglycidyl ether is added and mixed to react, resulting in mixture A. Polyether polyol is mixed with isocyanate and heated to react, resulting in mixture B. Mixtures A and B are then mixed to obtain a protective coating.

[0019] By adopting the above technical solution, the terminal epoxy silicone oil can open the ring and graft polysiloxane onto the copolymer backbone. The terminal amino polyether and polysiloxane segments can undergo block copolymerization reaction, making it easier to curl when subjected to external force. At the same time, the use of organosilicon thermal decomposition to generate a silicon-oxygen network structure can improve the thermal stability and toughness of the protective coating.

[0020] Polyether polyols react with isocyanates to form semi-prepolymers, which are then reacted with amino-terminated polyether-polysiloxane block copolymers under the action of diamino diglycidyl ether. The diamino diglycidyl ether molecule has an epoxy ring at its terminal end and amino groups at both ends, which can participate in the reaction between amino groups and isocyanate prepolymers to synthesize polyurea. This promotes the embedding of epoxy rings and organosilicon segments into the polyurea main chain, enabling the prepared protective coating to have both good tensile strength and flexibility. Under long-term outdoor use, it can reduce cracking and improve the corrosion resistance and crack resistance of concrete piers.

[0021] On the other hand, due to the embedding of epoxy groups from terminal epoxy silicone oil and diaminodiglycidyl ether in the polyurea backbone, when the concrete pier cracks under external force, the mesoporous silica spheres release the repair agent. In the alkaline environment rich in hydroxide ions within the concrete system, the primary amine in the aspartic acid molecular chain of the repair agent undergoes a ring-opening reaction with the epoxy groups in the polyurea structure. Multiple molecular chains crosslink to form a network structure, enhancing the viscosity of the concrete system and acting as a bond in the concrete cracks, further enhancing the self-healing effect of the concrete. Simultaneously, the triethanolamine in the repair agent can use its tertiary amine groups to attack the epoxy ring, lowering the reaction activation energy and enhancing the crosslinking reaction between the epoxy groups in the polyurea structure and the repair agent, achieving efficient crack bonding and preventing crack propagation.

[0022] Preferably, the heating reaction temperature of the mixture A is 75-85℃, and the heating reaction temperature of the mixture B is 75-85℃.

[0023] Secondly, this application provides a method for preparing a self-healing concrete pier, which adopts the following technical solution: A method for preparing a self-healing concrete pier includes the following specific steps: The concrete is mixed with the composite repair agent and then poured into a special mold for stone piers. After pouring, the fiber mesh is laid on the concrete surface and pressed evenly into the concrete to fix it. The surface is then smoothed with concrete. Finally, a protective coating is applied to the concrete surface. After curing, a self-healing concrete stone pier is obtained.

[0024] By employing the above-mentioned technical solutions, the synergistic effect of fiber mesh and composite repair agents in concrete can reduce large-area cracking, inhibit the continued extension and expansion of micro-cracks, seal cracks, and thus restore the density and strength of the concrete. The outermost layer is coated with a protective coating to inhibit corrosion of the concrete pier surface by external corrosive media. Through the synergistic effect of multiple actions, the crack resistance and impact resistance of the concrete are enhanced.

[0025] Preferably, the concrete is UHPC concrete and the fiber mesh is glass fiber mesh.

[0026] In summary, this application has the following beneficial effects: 1. This application utilizes a combination of fiber mesh and composite repair agent to synergistically enhance the crack resistance and impact resistance of concrete. The use of mesoporous silica spheres loaded with the repair agent enhances the internal strength of the concrete and consumes crack propagation energy. Furthermore, the mesoporous silica spheres, through their internal pores, can adsorb triethanolamine and aspartic acid. When the concrete is subjected to external impact or cracks appear, the encapsulation effect on the surface of the mesoporous silica spheres is disrupted, causing the release of the triethanolamine and aspartic acid repair agents. These triethanolamine and aspartic acid can directly react with calcium ions in the concrete to form calcium crystals, which directly fill the exposed cracks, sealing them and achieving a self-healing effect in the concrete.

[0027] 2. In this application, terminal epoxy silicone oil is used to graft polysiloxane onto the polyurea molecular chain. The thermal decomposition of organosilicon produces a silicon-oxygen network structure, which can improve the thermal stability and toughness of the protective coating. At the same time, diaminodiglycidyl ether is used as a chain extender to promote the embedding of epoxy groups and organosilicon segments into the polyurea molecular chain. When the concrete pier cracks under external force, the aspartic acid and triethanolamine in the repair agent crosslink with the epoxy ring, bonding the expanded cracks in a timely manner, thereby improving the self-healing ability of the concrete. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] All raw materials used in the examples are commercially available.

[0030] Preparation example of composite repair agent

[0031] Preparation Example 1 The composite repair agent raw materials include a repair agent and mesoporous silica spheres used to load the repair agent. The average particle size of the mesoporous silica spheres is 400 μm, and the average pore size is 100 nm. The repair agent includes triethanolamine and aspartic acid, with a mass ratio of 1:1. The surface of the mesoporous silica spheres loaded with the repair agent is coated with an encapsulating agent, which includes chitosan and silica sol. The average particle size of the silica sol is 20 nm, and the mass ratio of chitosan to silica sol is 1:1.

[0032] The preparation method of the composite repair agent includes the following specific steps: S1: Dissolve the repair agent in ethanol, then mix the mesoporous silica spheres with the dissolved repair agent. The mass ratio of the mesoporous silica spheres to the repair agent is 1:0.7. Stir slowly for 6 hours, centrifuge, and vacuum dry to obtain mesoporous silica microspheres loaded with the repair agent. Mix chitosan with a 2% (w / w) aqueous acetic acid solution to obtain a 2% (w / w) chitosan solution. Mix silica sol with water evenly to obtain a 5% (w / w) silica sol dispersion.

[0033] S2: Slowly mix the chitosan solution with the mesoporous silica microspheres loaded with the repair agent, stir slowly, centrifuge, wash and dry at 40°C to obtain chitosan-coated mesoporous silica microspheres. Then disperse the chitosan-coated mesoporous silica microspheres in a silica sol dispersion with a mass ratio of chitosan, silica sol and mesoporous silica microspheres of 0.5:0.5:1. Stir slowly, centrifuge and dry, wash and dry at 30°C to obtain the composite repair agent.

[0034] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that the encapsulant on the surface of the mesoporous silica spheres is chitosan.

[0035] The preparation method of the composite repair agent includes the following specific steps: S1: Dissolve the repair agent in ethanol, then mix the mesoporous silica balls with the dissolved repair agent. The mass ratio of the mesoporous silica balls to the repair agent is 1:0.7. Stir slowly for 6 hours, centrifuge, and vacuum dry to obtain mesoporous silica microspheres loaded with the repair agent. Mix chitosan with a 2% (w / w) aqueous acetic acid solution to obtain a 2% (w / w) chitosan solution.

[0036] S2: Mix chitosan solution with mesoporous silica microspheres loaded with repair agent. The mass ratio of chitosan to mesoporous silica microspheres is 0.5:1. Stir slowly, centrifuge, wash and dry at 40℃ to obtain chitosan-coated mesoporous silica microspheres, thus obtaining the composite repair agent.

[0037] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that the encapsulant on the surface of the mesoporous silica spheres is silica sol.

[0038] The preparation method of the composite repair agent includes the following specific steps: S1: Dissolve the repair agent in ethanol, then mix the mesoporous silica balls with the dissolved repair agent. The mass ratio of the mesoporous silica balls to the repair agent is 1:0.7. Stir slowly for 6 hours, centrifuge, and vacuum dry to obtain mesoporous silica microspheres loaded with the repair agent. Mix the silica sol with water evenly to obtain a silica sol dispersion with a mass fraction of 5%.

[0039] S2: Mix the mesoporous silica microspheres loaded with the repair agent with the silica sol dispersion, stir slowly, centrifuge and dry, wash and then dry at 30°C to obtain the composite repair agent.

[0040] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that... The preparation method of the composite repair agent includes the following specific steps: S1: Dissolve the repair agent in ethanol, then mix the mesoporous silica spheres with the dissolved repair agent. The mass ratio of the mesoporous silica spheres to the repair agent is 1:0.7. Stir slowly for 6 hours, centrifuge, and vacuum dry to obtain mesoporous silica microspheres loaded with the repair agent. Mix chitosan with a 2% (w / w) aqueous acetic acid solution to obtain a 2% (w / w) chitosan solution. Mix silica sol with water evenly to obtain a 5% (w / w) silica sol dispersion.

[0041] S2: Disperse mesoporous silica microspheres in silica sol dispersion, stir slowly, centrifuge and dry, wash and dry again at 30℃. Then, slowly drop chitosan solution into the aqueous solution of mesoporous silica microspheres coated with silica sol, stir slowly, centrifuge, wash and dry at 40℃. The mass ratio of chitosan, silica sol and mesoporous silica microspheres is 0.5:0.5:1 to obtain the composite repair agent.

[0042] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that the mesoporous silica spheres were pre-aminated.

[0043] The preparation method of the composite repair agent includes the following specific steps: S1: Mesoporous silica spheres were mixed with aminosilane KH-550, stirred, centrifuged, and dried to obtain aminated mesoporous silica spheres. The repair agent was dissolved in ethanol, and then the aminated mesoporous silica spheres were mixed with the dissolved repair agent. The mass ratio of mesoporous silica spheres, aminosilane and repair agent was 1:1.2:0.7. The mixture was stirred slowly for 6 hours, centrifuged, and vacuum dried to obtain mesoporous silica microspheres loaded with repair agent. Chitosan was mixed with a 2% (w / w) aqueous acetic acid solution to obtain a 2% (w / w) chitosan solution. Silica sol was mixed evenly with water to obtain a 5% (w / w) silica sol dispersion.

[0044] S2: Mix the chitosan solution with the mesoporous silica microspheres loaded with the repair agent, stir slowly, centrifuge, wash and dry at 40°C to obtain chitosan-coated mesoporous silica microspheres. Then disperse the chitosan-coated mesoporous silica microspheres in a silica sol dispersion with a mass ratio of chitosan, silica sol and mesoporous silica microspheres of 0.5:0.5:1. Stir slowly, centrifuge and dry, wash and dry at 30°C to obtain the composite repair agent.

[0045] Preparation Example 6 The difference between Preparation Example 6 and Preparation Example 5 is that the mass ratio of mesoporous silica spheres to aminosilane and repair agent is 1:1:0.5.

[0046] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 5 is that the mass ratio of mesoporous silica spheres to aminosilane and repair agent is 1:1.5:0.8.

[0047] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 1 is that the surface of the mesoporous silica spheres is not coated with an encapsulating agent.

[0048] The preparation method of the composite repair agent includes the following specific steps: Mesoporous silica spheres were mixed with a repair agent dissolved in ethanol at a mass ratio of 1:0.7. The mixture was stirred slowly for 6 hours, centrifuged, and vacuum dried to obtain mesoporous silica microspheres loaded with the repair agent. Example Example 1

[0049] This embodiment provides a self-healing concrete pier, including concrete, self-healing material and protective coating. The concrete is UHPC concrete, purchased from Tianjin Keen Construction Technology Co., Ltd. The self-healing material includes fiber mesh and composite repair agent. The composite repair agent is derived from Preparation Example 1. The fiber mesh is glass fiber mesh with an average pore size of 300 μm. The protective coating comprises the following raw materials in parts by weight: 27 kg of amino-terminated polyether, 27 kg of isocyanate, 32 kg of epoxy silicone oil, 2 kg of diamino diglycidyl ether, and 17 kg of polyether polyol; wherein the amino-terminated polyether is D2000, the isocyanate is hexamethylene diisocyanate, the viscosity of the epoxy silicone oil (25℃) is 1500 mpa.s, and the polyether polyol is polytetrahydrofuran ether diol PTMEG-2000.

[0050] The preparation method of self-healing concrete piers includes the following specific steps: S1: Under the protection of nitrogen, terminal epoxy silicone oil is added dropwise to terminal amino polyether and heated at 80°C for 12 hours. Then, diamino diglycidyl ether is added dropwise and mixed, and the reaction is continued at 80°C to obtain mixture A. Under the protection of nitrogen, polyether polyol and isocyanate are mixed and heated at 80°C for 4 hours to obtain mixture B. Mixtures A and B are mixed to obtain a protective coating.

[0051] S2: Mix concrete and composite repair agent at a mass ratio of 10:1, stir evenly, and then pour into a special mold for stone piers. After pouring, lay fiber mesh on the concrete surface and press the fiber mesh evenly into the concrete by 0.5mm. Fix the fiber mesh and smooth the surface with concrete. Finally, apply protective coating to the concrete surface to form a coating with an average thickness of 2mm. After curing, a self-healing concrete stone pier is obtained.

[0052] Example 2

[0053] The difference between Example 2 and Example 1 is that the average pore size of the fiber mesh in the self-healing concrete pier material is 500 μm.

[0054] Example 3 The difference between Example 3 and Example 1 is that the protective coating in the self-healing concrete pier raw material includes the following raw materials in parts by weight: 20 kg of amino-terminated polyether, 35 kg of isocyanate, 25 kg of epoxy silicone oil, 1 kg of diamino diglycidyl ether, and 25 kg of polyether polyol.

[0055] Example 4 The difference between Example 4 and Example 1 is that the protective coating in the self-healing concrete pier raw material includes the following raw materials in parts by weight: 35 kg of amino-terminated polyether, 20 kg of isocyanate, 40 kg of epoxy silicone oil, 3 kg of diamino diglycidyl ether, and 10 kg of polyether polyol.

[0056] Example 5 The difference between Example 5 and Example 1 is that the protective coating in the self-healing concrete pier material does not use end epoxy silicone oil.

[0057] The preparation method of self-healing concrete piers includes the following specific steps: S1: Under the protection of nitrogen, diamino diglycidyl ether is added dropwise to the amino-terminated polyether to obtain mixture A; under the protection of nitrogen, polyether polyol and isocyanate are mixed and heated at 80°C for 4 hours to obtain mixture B; mixtures A and B are mixed to obtain a protective coating.

[0058] S2: Mix concrete and composite repair agent at a mass ratio of 10:1, stir evenly, and then pour into a special mold for stone piers. After pouring, lay fiber mesh on the concrete surface and press the fiber mesh evenly into the concrete by 0.5mm. Fix the fiber mesh and smooth the surface with concrete. Finally, apply protective coating to the concrete surface to form a coating with an average thickness of 2mm. After curing, a self-healing concrete stone pier is obtained.

[0059] Example 6 The difference between Example 6 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 4.

[0060] Example 7 The difference between Example 7 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 5.

[0061] Example 8 The difference between Example 8 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 6.

[0062] Example 9 The difference between Example 9 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 7.

[0063] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 2.

[0064] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 3.

[0065] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material is derived from Preparation Example 8.

[0066] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the composite repair agent in the self-healing concrete pier raw material does not use mesoporous silica ball-loaded repair agent.

[0067] The preparation method of self-healing concrete piers includes the following specific steps: S1: Under the protection of nitrogen, terminal epoxy silicone oil is added dropwise to terminal amino polyether and heated at 80°C for 12 hours. Then, diamino diglycidyl ether is added dropwise and mixed, and the reaction is continued at 80°C to obtain mixture A. Under the protection of nitrogen, polyether polyol and isocyanate are mixed and heated at 80°C for 4 hours to obtain mixture B. Mixtures A and B are mixed to obtain a protective coating.

[0068] S2: Mix concrete and repair agent at a mass ratio of 10:1, stir evenly, and then pour into a special mold for stone piers. After pouring, lay fiber mesh on the concrete surface and press the fiber mesh evenly into the concrete by 0.5mm. Fix the fiber mesh and smooth the surface with concrete. Finally, apply protective coating to the concrete surface to form a coating with an average thickness of 2mm. After curing, a self-healing concrete stone pier is obtained.

[0069] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the self-healing concrete pier does not use fiber mesh.

[0070] Performance testing The self-healing concrete stone blocks provided in Examples 1-9 and Comparative Examples 1-5 of this application were subjected to the following performance tests, and the specific test results are shown in Table 1.

[0071] Detection methods I. Self-healing effect Ten circular specimens (φ100*50mm) of concrete stone piers prepared in this application were made. After 7 days of curing, through cracks with a width of 0.2-0.5mm were created using a universal testing machine. The initial water seepage through the through cracks was tested using an anti-seepage device. The specimens were then soaked in water for curing, and the water seepage was tested after 10 days and 30 days of soaking. Finally, the degree of repair of the concrete cracks was evaluated by the ratio of the water seepage after curing to the initial water seepage. The lower the ratio, the better the crack repair. When the result is 0, it means that the crack has been repaired. The water seepage of each test was taken as the average value of all specimens.

[0072] II. Crack Resistance Using standard point line gauges, film rulers, comparison cards, and feeler gauges, the crack condition of the concrete stone piers prepared in this application was measured on the 7th day of curing, and the total length of the cracks, the average length of the cracks, and the maximum width of the cracks were recorded.

[0073] III. Compressive Strength The compressive strength of the concrete stone pier prepared in this application was tested after 28 days of curing, in accordance with the standard GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0074] IV. Permeability Grade The water permeability resistance of the concrete stone piers prepared in this application was tested in accordance with GB / T 50082-2009, "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".

[0075] Table 1: Performance Test Results Data Table

[0076] The performance test results show that the self-healing concrete pier prepared in this application has good self-healing properties, can fill cracks in a timely manner, reduce crack propagation, and improve the durability of the concrete pier. A comparison between Comparative Example 1 and Example 1 shows that in Comparative Example 1, without the use of fiber mesh, the compressive strength of the prepared concrete is significantly reduced, and the self-healing performance is also decreased. This further illustrates that the synergistic effect of fiber mesh and self-healing material in this application enables the prepared concrete pier to possess both good compressive strength and self-healing properties.

[0077] A comparison of Examples 1 and 2 shows that Example 2 uses fiber mesh with a larger pore size than mesoporous silica spheres. Performance testing results show that the self-healing performance of the concrete prepared in Example 2 is reduced. This further illustrates that in the concrete system, mesoporous silica spheres can partially migrate to the surface. During the manufacturing and processing process, they may be subjected to external friction, which may cause premature release of the repair agent or detachment from the concrete surface, thereby reducing the self-healing performance of the concrete.

[0078] A comparison of Examples 1 and 5 shows that Example 5 does not use end-epoxy silicone oil. Performance test results show that the impermeability of the concrete prepared in Example 5 is significantly reduced, and its self-healing performance is also reduced. This further illustrates that the repair agent used in this application can react with the epoxy groups in the end-epoxy silicone oil, enhance the viscosity of the concrete system, and thus bond small cracks, thereby enhancing the self-healing performance of the concrete.

[0079] A comparison of Examples 1 and 6 shows that in Example 6, the mesoporous silica microspheres were first encapsulated with silica sol and then chitosan. The performance test results show that the self-healing effect of the concrete was reduced, further indicating that the encapsulation sequence used for the mesoporous silica microspheres in Example 1 was superior.

[0080] As can be seen from Examples 7-9, pre-ammoniation modification of mesoporous silica spheres can enhance the loading effect of mesoporous silica microspheres on the repair agent, thereby improving the self-healing performance of concrete.

[0081] As can be seen from Comparative Examples 1-2, changing any component of the encapsulant used in this application results in a decrease in the self-healing performance of the prepared concrete, as shown by the performance test results. This further illustrates that the encapsulant used in this application, which combines chitosan and silica sol, enhances the stability of the repair agent within the mesoporous silica microsphere channels through a dual action. Simultaneously, it promotes the timely release of the repair agent from the mesoporous silica microsphere channels, generating calcium crystal precipitates in the concrete and achieving the self-healing performance of the concrete.

[0082] Comparative Examples 3 and 4 show that in Comparative Example 3, the surface of the mesoporous silica spheres was not coated with a sealant, while in Comparative Example 4, the repair agent was directly added to the concrete system. Performance testing results indicate that the self-healing performance of the concrete further decreased significantly. The concrete prepared in Comparative Example 4 almost lost its self-healing properties, and microcracks were also generated during the curing shrinkage of the concrete. This further illustrates that without a sealant coating on the surface of the mesoporous silica spheres, the repair agent may directly contact calcium ions in the concrete system, directly generating calcium precipitates. Consequently, when cracks appear in the concrete, it can no longer fill the cracks, leading to the loss of self-healing properties.

[0083] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A self-healing concrete pier, characterized in that, The invention includes concrete, self-healing materials, and protective coatings. The self-healing materials include fiber mesh and composite repair agents. The composite repair agents are made from repair agents and mesoporous silica spheres for loading the repair agents. The surface of the mesoporous silica spheres loaded with repair agents is coated with an encapsulating agent. The repair agents include triethanolamine and aspartic acid. The encapsulating agents include chitosan and silica sol.

2. The self-healing concrete pier according to claim 1, characterized in that, The fiber mesh has a pore size of 200-400 μm, and the mesoporous silica spheres have a particle size of 300-500 μm.

3. The self-healing concrete pier according to claim 2, characterized in that, The mesoporous silica spheres are pre-aminated and then loaded with a repair agent, including the following specific steps: dissolving the mesoporous silica spheres in anhydrous ethanol, adding aminosilane and mixing, stirring and centrifuging, drying to obtain aminated mesoporous silica spheres, then mixing the aminated mesoporous silica spheres, the repair agent and ethanol, stirring evenly, centrifuging, vacuum drying to obtain mesoporous silica microspheres loaded with the repair agent, and then coating the mesoporous silica microspheres loaded with the repair agent with an encapsulating agent to complete the process.

4. The self-healing concrete pier according to claim 3, characterized in that, The mass ratio of the mesoporous silica spheres to aminosilane and the repair agent is 1:(1-1.5):(0.5-0.8).

5. The self-healing concrete pier according to claim 3, characterized in that, The mesoporous silica microspheres loaded with the repair agent were first coated with chitosan and then coated with silica sol.

6. The self-healing concrete pier according to claim 1, characterized in that, The protective coating comprises the following raw materials in parts by weight: 20-35 parts of amino-terminated polyether, 20-35 parts of isocyanate, 25-40 parts of epoxy silicone oil, 1-3 parts of diamino diglycidyl ether, and 10-25 parts of polyether polyol.

7. The self-healing concrete pier according to claim 6, characterized in that, The preparation method of the protective coating includes the following specific steps: Under the protection of nitrogen, terminal epoxy silicone oil is dropped into terminal amino polyether and heated to react. Then, diamino diglycidyl ether is added and mixed to react, resulting in mixture A. Polyether polyol is mixed with isocyanate and heated to react, resulting in mixture B. Mixtures A and B are then mixed to obtain a protective coating.

8. The self-healing concrete pier according to claim 4, characterized in that, The heating reaction temperature of mixture A is 75-85℃, and the heating reaction temperature of mixture B is 75-85℃.

9. A method for preparing a self-healing concrete pier as described in any one of claims 1-8, characterized in that, The specific steps include the following: The concrete is mixed with the composite repair agent and then poured into a mold. After pouring, the fiber mesh is laid on the concrete surface and pressed evenly into the concrete to fix it. The surface is then smoothed with concrete. Finally, a protective coating is applied to the concrete surface. After curing, a self-healing concrete pier is obtained.

10. The method for preparing a self-healing concrete pier according to claim 9, characterized in that, The concrete is UHPC concrete, and the fiber mesh is glass fiber mesh.

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