Centrifugal casting corrosion-resistant concrete pipeline and preparation method thereof

Abstract

The invention relates to the technical field of concrete pipelines, and particularly discloses a centrifugal casting corrosion-resistant concrete pipeline and a preparation method thereof. A centrifugal casting corrosion-resistant concrete pipeline comprises a pipe body and a glass fiber reinforcement cage embedded in the pipe body, and the pipe body is formed by centrifugal casting of corrosion-resistant polymer concrete. The corrosion-resistant polymer concrete is prepared from magnesium phosphate cement, fly ash, slag powder, machine-made sand, glass fibers, styrene-acrylic emulsion, double-layer shell structure microcapsules, an additive and water, the double-layer shell structure microcapsule comprises a core material, an inner layer shell and an outer layer shell from inside to outside, the core material is phenolic resin and nano titanium dioxide, the inner layer shell is an epoxy resin-polyamide curing agent copolymer, and the outer layer shell is a polymethylacrylic acid-acrylamide copolymer. The concrete pipeline has excellent corrosion resistance, and protection and repair of the concrete pipeline in a corrosion environment can be achieved through the double-layer shell structure microcapsules.

Description

Technical Field

[0001] This application relates to the technical field of concrete pipes, and more specifically, it relates to a centrifugally cast corrosion-resistant concrete pipe and its preparation method. Background Art

[0002] As an important building material, concrete pipes have many applications in many fields such as urban infrastructure construction, industrial production, and water conservancy projects. In municipal engineering, it plays a key role in the water supply and drainage system. Whether it is the rapid discharge of urban rainwater or the proper collection and transportation of domestic sewage, concrete pipes can efficiently complete the tasks, effectively reducing the risk of urban waterlogging and ensuring the normal operation of residents' lives. In traffic engineering, in highway and railway construction, concrete pipes are used for subgrade drainage, which can ensure the stability of the road structure and extend the service life of the road. In addition, in scenarios such as irrigation, mine drainage, and chemical wastewater treatment, concrete pipes play an irreplaceable and important role due to their good mechanical properties, high cost performance, and relatively simple installation process.

[0003] At present, the technology of concrete pipes is constantly developing. For example, the patent application document with the publication number CN117739176A discloses a steel cylinder type concrete pipe and its preparation method. By successively arranging several prestressed steel wire layers on the outer side of the pipe core and a prestressed concrete protective layer on the outer side of the prestressed steel wire layers, the several prestressed steel wire layers are used to provide prestress for the concrete pipe; realizing multi-layer winding of prestressed steel wires, improving the bearing capacity of the pipe without increasing the wall thickness of the pipe, and solving the problems of hollowing and peeling of the protective layer under high working pressure or deep overburden conditions. However, in actual applications, existing reinforced concrete pipes still have significant defects. When in a corrosive environment, such as industrial wastewater discharge areas, coastal saline-alkali areas, etc., the pipes are extremely vulnerable to chemical erosion. The long-term erosion effect will not only significantly shorten the service life of the pipes, but also often cause serious problems such as rusting, cracking, and even leakage.

[0004] Delving deep into the root causes of these problems, on the one hand, the concrete used in existing reinforced concrete pipes has its own pore structure. The connected or semi-connected pores provide penetration channels for corrosive media, so there is inherently a problem of poor corrosion resistance. On the other hand, when corrosive media penetrate into the pipe body, it will cause the steel bars inside the pipe to rust. As the degree of rusting deepens, the mechanical properties of the steel bars gradually decline, and they can no longer provide sufficient support and restraint for the concrete structure, thereby leading to concrete cracking. Once cracks appear in the concrete, corrosive media will more easily penetrate into the interior of the pipe, forming a vicious cycle and accelerating the damage of the pipe. Therefore, how to effectively improve the corrosion resistance of the pipe, overcome the drawbacks brought by the rusting of traditional pipes, and then reduce the maintenance cost of concrete pipes and extend their service life has become a key technical problem that urgently needs to be solved in the current technical field of concrete pipes. Summary of the Invention

[0005] In order to improve the corrosion resistance of concrete pipes, the present application provides a centrifugally cast corrosion-resistant concrete pipe and its preparation method.

[0006] The centrifugally cast corrosion-resistant concrete pipe provided by the present application adopts the following technical solutions: A centrifugally cast corrosion-resistant concrete pipe, comprising a pipe body and a glass fiber reinforcement cage buried in the pipe body. The pipe body is centrifugally cast from corrosion-resistant polymer concrete, and the corrosion-resistant polymer concrete is made from the following raw materials in parts by weight: 40 - 50 parts of magnesium phosphate cement; 10 - 15 parts of fly ash; 5 - 10 parts of slag powder; 50 - 70 parts of manufactured sand; 3 - 5 parts of glass fiber; 10 - 25 parts of styrene-acrylic emulsion; 10 - 20 parts of double-shell structure microcapsules; 0.5 - 1.5 parts of admixture; 20 - 30 parts of water; The double-shell structure microcapsules include a core material, an inner shell, and an outer shell from the inside to the outside. The core material is phenolic resin and nano-titanium dioxide, the inner shell is an epoxy resin-polyamide curing agent copolymer, and the outer shell is a polymethacrylic acid-acrylamide copolymer.

[0007] By adopting the above technical solution, a corrosion-resistant polymer concrete centrifugally cast pipe body is used. In the corrosion-resistant polymer concrete, each raw material acts synergistically. Magnesium phosphate cement, fly ash, slag powder, and manufactured sand form the concrete skeleton; glass fiber enhances toughness and has good water resistance, alkali resistance, and weather resistance. In the concrete, it can fill the pores of the magnesium phosphate cement stone, improve the compactness of the concrete, and thus enhance the corrosion resistance of the concrete. At the same time, the polymer molecules in the styrene-acrylic emulsion can form a continuous protective film on the surface of the concrete, playing a role in isolating external corrosion media. The glass fiber reinforcement cage replaces traditional steel bars, avoiding the problem of steel bar corrosion, significantly improving the corrosion resistance of the pipeline, overcoming the drawbacks brought by the corrosion of traditional steel bars, extending the service life of the pipeline, and reducing the maintenance cost.

[0008] By introducing double-shell structure microcapsules with phenolic resin and nano-titanium dioxide as the core materials, the phenolic resin contains active groups such as hydroxyl groups and hydroxymethyl groups. When the microcapsules rupture and release the phenolic resin, the phenolic resin can undergo a polycondensation reaction with the unreacted active groups in the styrene-acrylic resin to form a cross-linked structure. As the reaction progresses, the phenolic resin gradually solidifies to form a strong three-dimensional network. This network can grow in the cracks and pores of the concrete, filling these defects, improving the compactness of the concrete, enhancing its impermeability and corrosion resistance, and achieving the repair and protection of the concrete. Nano-titanium dioxide has high chemical activity and a large specific surface area. When it is released from the microcapsules, on the one hand, the nano-titanium dioxide particles can adhere to the surface of the styrene-acrylic resin through physical adsorption, playing a role in strengthening and filling, and improving the mechanical properties and barrier properties of the protective film formed by the styrene-acrylic resin. In addition, the photocatalytic effect of nano-titanium dioxide can decompose organic pollutants and some corrosive substances on the surface of the concrete, reducing their erosion of the concrete, thereby improving the corrosion resistance and durability of the concrete, and achieving the repair and protection of the concrete.

[0009] The outer shell poly(methacrylic acid-acrylamide) copolymer has good pH sensitivity. When the concrete pipe encounters a corrosive environment in the use environment, the change in pH in the environment will protonate the carboxyl groups on the molecular chain of the poly(methacrylic acid-acrylamide) copolymer, increasing the solubility of the copolymer and stretching the molecular chain. This change will cause the structure of the outer shell to become loose, and at the same time, it will also change the interface between the outer shell and the inner shell. Since the inner shell is an epoxy resin-polyamide curing agent copolymer, its molecular structure contains active groups such as hydroxyl (-OH) and amino (-NH2). When the molecular chain of the poly(methacrylic acid-acrylamide) copolymer in the outer shell stretches, the carboxyl groups on its molecular chain react with the active groups of the inner shell, such as esterification reaction or amidation reaction. These reactions will cause the structure of the inner shell to be damaged, thus promoting the rupture of the inner shell and accurately releasing the repair particles of the core material. By designing the double-layer shell structure, on the one hand, it can ensure the mechanical strength of the double-layer shell structure and ensure that the microcapsules do not rupture under normal working conditions such as concrete preparation and transportation. On the other hand, it can accurately and quickly release the core material when the pipeline faces a corrosive environment, realizing the repair and protection of concrete.

[0010] Optionally, the double-layer shell structure microcapsules are prepared by the following method: A. Mix nano-titanium dioxide, liquid phenolic resin and epoxy resin, stir at 60-70 °C for 1-3 h, then perform ultrasonic dispersion for 20-30 min to obtain a core material-epoxy resin mixture. Then add cyclohexane and emulsifier, stir for 20-30 min, and then add polyamide curing agent and stir for 20-30 min to obtain an emulsion; B. Mix methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water to obtain an aqueous solution. Add the emulsion to the aqueous solution, then add ammonium persulfate solution, heat up to 50-60 °C, react for 1-3 h, cool and then centrifuge to separate the solid product, and then wash and dry the solid product to obtain the double-layer shell structure microcapsules.

[0011] By adopting the above technical scheme, a preparation method of double-layer shell structure microcapsules is provided. The above preparation method can ensure the stable structure and uniform performance of the microcapsules. Using the double-layer emulsion method, first prepare the core material-epoxy resin emulsion, and then form the outer shell by interfacial polymerization. The step-by-step process ensures the complete encapsulation of the core material and the precise formation of the double-layer structure, which is beneficial to improving the use performance of the double-layer shell structure microcapsules and further helps to enhance the corrosion resistance of the corrosion-resistant polymer concrete.

[0012] Optionally, in step A, the mass ratio of nano-titanium dioxide, liquid phenolic resin and epoxy resin is 1:(5-8):(10-12).

[0013] Optionally, the addition amount of cyclohexane in step A is 30%-50% of the epoxy resin, the addition amount of the emulsifier is 3%-5% of the epoxy resin, and the addition amount of the polyamide curing agent is 30%-40% of the epoxy resin.

[0014] Optionally, in step B, the mass ratio of methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water is (1-3):1:(0.02-0.05):(0.05-0.1):(10-15).

[0015] Optionally, in step B, the mass ratio of the aqueous solution to the emulsion is (3-5):1.

[0016] Optionally, in step B, the mass concentration of the ammonium persulfate solution is 10%-15%, and the addition amount of the ammonium persulfate solution is 3%-5% of the total mass of methacrylic acid and acrylamide.

[0017] By adopting the above technical solution, the raw material ratio for preparing the microcapsules is defined to ensure the strength of the inner shell and the pH sensitivity of the outer shell. The appropriate ratio enables the inner shell (epoxy resin-polyamide) to have high mechanical strength, and the outer shell (polymethacrylic acid-acrylamide) to accurately respond to the corrosion environment. Moreover, the synergistic reaction between the raw materials improves the comprehensive performance of the microcapsules.

[0018] Optionally, the glass fiber reinforcement cage is formed by winding glass fiber bars. The diameter of the glass fiber bars is 5-7 mm, and the glass fiber reinforcement cage is in a rhombic grid structure with a side length of the rhombic grid being 40-60 mm.

[0019] By adopting the above technical solution, the shape of the glass fiber reinforcement cage is defined. Its rhombic grid structure, suitable spacing and diameter enhance the mechanical properties of the pipeline while avoiding stress concentration from damaging the pipe body; replacing steel bars eliminates rust, and cooperating with corrosion-resistant concrete improves the overall corrosion resistance of the concrete pipeline.

[0020] Optionally, the solid content of the styrene-acrylic emulsion is 40%-50%.

[0021] By adopting the above technical solution, the solid content of the styrene-acrylic emulsion is specified to ensure that it fully fills the pores in the concrete, forms a continuous and dense protective film, optimizes the polymer film-forming effect, and enhances the impermeability and corrosion resistance of the concrete.

[0022] This application also provides a preparation method for a centrifugally cast corrosion-resistant concrete pipeline, adopting the following technical solution: A preparation method for a centrifugally cast corrosion-resistant concrete pipeline includes the following steps: S1. Mix magnesium phosphate cement, fly ash, slag powder, manufactured sand, glass fiber, styrene-acrylic emulsion, double-layer shell structure microcapsules, admixtures and water, and stir for 5 - 10 min to obtain corrosion-resistant polymer concrete; S2. Place the glass fiber reinforcement cage in a mold, then inject the corrosion-resistant polymer concrete into the mold for centrifugal molding, and obtain a centrifugally cast corrosion-resistant concrete pipe after curing and demolding.

[0023] Through the standardized pipeline preparation process, mixing and stirring ensure the uniform dispersion of raw materials, centrifugal molding makes the concrete dense and the structure uniform, and the curing and demolding processes ensure the strength and dimensional accuracy of the pipeline, stably producing high-quality corrosion-resistant concrete pipes.

[0024] In summary, the present application has the following beneficial effects: 1. The present application uses a glass fiber reinforcement cage to replace traditional steel bars, and centrifugally casts the pipe body with corrosion-resistant polymer concrete, significantly improving the corrosion resistance of the concrete pipe. The glass fiber reinforcement cage has excellent corrosion resistance, fundamentally eliminating the problem of concrete cracking caused by steel bar corrosion, and effectively avoiding pipeline damage caused by the decline of the mechanical properties of steel bars. In the corrosion-resistant polymer concrete, magnesium phosphate cement, fly ash, slag powder and manufactured sand form a solid skeleton, glass fiber enhances its toughness, styrene-acrylic emulsion fills the pores and forms a continuous protective film on the concrete surface, isolating external corrosive media, and further enhancing the compactness and impermeability of the concrete. The synergistic effect of various raw materials comprehensively improves the corrosion resistance of the pipeline, extends its service life, reduces maintenance costs, and effectively solves the problem of poor durability of traditional reinforced concrete pipes in corrosive environments.

[0025] 2. The present application introduces double-layer shell structure microcapsules with phenolic resin and nano-titanium dioxide as the core materials, realizing the intelligent repair and corrosion resistance improvement of the concrete pipe. When the pipeline is corroded, the poly(methacrylic acid-acrylamide) copolymer on the outer layer of the microcapsule is protonated due to the change of environmental pH, its solubility increases, the molecular chain stretches, the structure becomes loose and undergoes an esterification or amidation reaction with the inner layer shell, prompting the inner layer shell to rupture and accurately release the core materials. The unreacted active groups in phenolic resin and styrene resin condense to form a strong three-dimensional network, filling cracks and pores; nano-titanium dioxide enhances the performance of the protective film through physical adsorption and decomposes organic pollutants and corrosive substances on the concrete surface by photocatalysis. This intelligent repair mechanism can respond in a timely manner when the pipeline is corroded, effectively repair the concrete structure, and further enhance the corrosion resistance and durability of the pipeline.

[0026] 3. The present application clarifies the preparation method of the double-shell structure microcapsules and the proportion of each raw material, and standardizes the preparation process of the concrete pipes, ensuring the stability and reliability of the product quality. The precise microcapsule preparation process and raw material proportion ensure that the inner shell has sufficient mechanical strength to withstand the external forces during the preparation and transportation of concrete, while enabling the outer shell to have precise pH sensitivity to achieve the accurate release of the core material. The standardized pipe preparation process ensures the uniform dispersion of the concrete raw materials and the dense and uniform structure of the pipe body, thus stably producing high-quality corrosion-resistant concrete pipes and ensuring the consistency and stability of the product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the infrared spectrogram of the double-shell structure microcapsules prepared in Preparation Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following further elaborates the present application in conjunction with the embodiments.

[0029] Preparation Examples of Double-Shell Structure Microcapsules Preparation Example 1 The double-shell structure microcapsules are prepared by the following method: A. Mix 1 kg of nano-titanium dioxide, 5 kg of liquid phenolic resin and 10 kg of epoxy resin E51, stir at 60 °C and 300 rpm for 1 h, then perform ultrasonic dispersion at an ultrasonic frequency of 40 kHz for 20 min to obtain a core material-epoxy resin mixture. Then add 3 kg of cyclohexane and 0.3 kg of emulsifier, stir at a speed of 10,000 rpm for 20 min, and then add 3 kg of polyamide 650 curing agent and continue to stir at a speed of 10,000 rpm for 20 min to obtain an emulsion; B. Mix 1 kg of methacrylic acid, 1 kg of acrylamide, 0.02 kg of N,N'-methylenebisacrylamide, 0.05 kg of sodium dodecylbenzenesulfonate and 10 kg of deionized water to obtain an aqueous solution. Add the emulsion to the aqueous solution at a mass ratio of the aqueous solution to the emulsion of 3:1. Then add 0.06 kg of ammonium persulfate solution with a mass concentration of 10%, heat up to 50 °C, react for 1 h, and introduce nitrogen for protection during the reaction. After the reaction, cool to room temperature, separate the solid product by centrifugation, wash the solid product three times with deionized water and anhydrous ethanol respectively, and then dry in a vacuum drying oven at 40 °C for 6 h to obtain the double-shell structure microcapsules.

[0030] Preparation Example 2 The double-shell structure microcapsules are prepared by the following method: A. Mix 1 kg of nano-titanium dioxide, 6.5 kg of liquid phenolic resin, and 11 kg of epoxy resin E51, stir at 65 °C and 300 rpm for 2 h, then perform ultrasonic dispersion at an ultrasonic frequency of 35 kHz for 25 min to obtain a core material-epoxy resin mixture. Then add 4.4 kg of cyclohexane and 0.44 kg of emulsifier, stir at a speed of 10,000 rpm for 25 min, and then add 3.85 kg of polyamide 650 curing agent, and continue to stir at a speed of 10,000 rpm for 25 min to obtain an emulsion; B. Mix 2 kg of methacrylic acid, 1 kg of acrylamide, 0.04 kg of N,N'-methylenebisacrylamide, 0.07 kg of sodium dodecylbenzenesulfonate, and 12 kg of deionized water to obtain an aqueous solution. Add the emulsion to the aqueous solution at a mass ratio of the aqueous solution to the emulsion of 4:1. Then add 0.12 kg of ammonium persulfate solution with a mass concentration of 12%, heat up to 55 °C, react for 2 h, introduce nitrogen protection during the reaction, cool to room temperature after the reaction, separate the solid product by centrifugation, wash the solid product three times with deionized water and anhydrous ethanol respectively, and then dry in a vacuum drying oven at a temperature of 40 °C for 6 h to obtain double-layer shell-structured microcapsules.

[0031] Preparation Example 3 The double-layer shell-structured microcapsules are prepared by the following method: A. Mix 1 kg of nano-titanium dioxide, 8 kg of liquid phenolic resin, and 12 kg of epoxy resin E51, stir at 70 °C and 300 rpm for 3 h, then perform ultrasonic dispersion at an ultrasonic frequency of 30 kHz for 30 min to obtain a core material-epoxy resin mixture. Then add 6 kg of cyclohexane and 0.6 kg of emulsifier, stir at a speed of 10,000 rpm for 30 min, and then add 4.8 kg of polyamide 650 curing agent, and continue to stir at a speed of 10,000 rpm for 30 min to obtain an emulsion; B. Mix 3 kg of methacrylic acid, 1 kg of acrylamide, 0.05 kg of N,N'-methylenebisacrylamide, 0.1 kg of sodium dodecylbenzenesulfonate, and 15 kg of deionized water to obtain an aqueous solution. Add the emulsion to the aqueous solution at a mass ratio of the aqueous solution to the emulsion of 5:1. Then add 0.2 kg of ammonium persulfate solution with a mass concentration of 15%, heat up to 60 °C, react for 3 h, introduce nitrogen protection during the reaction, cool to room temperature after the reaction, separate the solid product by centrifugation, wash the solid product three times with deionized water and anhydrous ethanol respectively, and then dry in a vacuum drying oven at a temperature of 40 °C for 6 h to obtain double-layer shell-structured microcapsules.

[0032] Preparation Example 4 Single-layer shell structure microcapsules with a core material of phenolic resin and nano-titanium dioxide and a shell of epoxy resin-polyamide curing agent copolymer are prepared by the following method: A. Mix 1 kg of nano-titanium dioxide, 8 kg of liquid phenolic resin and 12 kg of epoxy resin E51, stir at 70 °C and 300 rpm for 3 h, then perform ultrasonic dispersion at an ultrasonic frequency of 30 kHz for 30 min to obtain a core material-epoxy resin mixture. Then add 6 kg of cyclohexane and 0.6 kg of emulsifier, stir at a speed of 10,000 rpm for 30 min, and then add 4.8 kg of polyamide 650 curing agent and continue to stir at a speed of 10,000 rpm for 30 min to obtain an emulsion; B. Heat the emulsion to 45 °C and react for 3 h. During the reaction, nitrogen is introduced for protection. After the reaction, cool it to room temperature, separate the solid product by centrifugation, wash the solid product three times with deionized water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 40 °C for 6 h to obtain single-layer shell structure microcapsules with an epoxy resin-polyamide curing agent copolymer as the shell.

[0033] Preparation Example 5 Single-layer shell structure microcapsules with a core material of phenolic resin and nano-titanium dioxide and a shell of polymethacrylic acid-acrylamide copolymer are prepared by the following method: A. Add 1 kg of nano-titanium dioxide and 8 kg of liquid phenolic resin to 6 kg of cyclohexane, stir at 70 °C and 300 rpm for 3 h, and then perform ultrasonic dispersion at 30 kHz for 30 min to obtain a uniform core material dispersion. Mix 3 kg of methacrylic acid, 1 kg of acrylamide, 0.05 kg of N,N'-methylenebisacrylamide, 0.1 kg of sodium dodecylbenzenesulfonate with 15 kg of deionized water to form an aqueous solution. Under stirring at 10,000 rpm, add the core material dispersion to the aqueous solution and continue to stir for 30 min to form an emulsion; B. Add 0.2 kg of ammonium persulfate solution with a mass concentration of 15% to the emulsion, introduce nitrogen for protection, heat it to 60 °C and react for 3 h. During the reaction, nitrogen is introduced for protection. After the reaction, cool it to room temperature, separate the solid product by centrifugation, wash the solid product three times with deionized water and anhydrous ethanol respectively, and then dry it in a vacuum drying oven at 40 °C for 6 h to obtain single-layer shell structure microcapsules with a polymethacrylic acid-acrylamide copolymer as the shell.

[0034] Example Example 1 A centrifugally cast corrosion-resistant concrete pipe, comprising a pipe body and a glass fiber reinforcement cage embedded in the pipe body. The glass fiber reinforcement cage is formed by winding glass fiber bars. The diameter of the glass fiber bars is 5 mm. The glass fiber reinforcement cage is a rhombic grid structure, and the side length of the rhombic grid is 40 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material components and ratios of the corrosion-resistant polymer concrete are shown in Table 1. Among them, the average length of the glass fiber is 20 mm, the solid content of the styrene-acrylic emulsion is 40%, the double-shell structure microcapsules are the double-shell structure microcapsules prepared in Preparation Example 1, and the admixture is a polycarboxylate water reducer.

[0035] Example 2 A centrifugally cast corrosion-resistant concrete pipe, comprising a pipe body and a glass fiber reinforcement cage embedded in the pipe body. The glass fiber reinforcement cage is formed by winding glass fiber bars. The diameter of the glass fiber bars is 6 mm. The glass fiber reinforcement cage is a rhombic grid structure, and the side length of the rhombic grid is 50 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material components and ratios of the corrosion-resistant polymer concrete are shown in Table 1. Among them, the average length of the glass fiber is 20 mm, the solid content of the styrene-acrylic emulsion is 45%, the double-shell structure microcapsules are the double-shell structure microcapsules prepared in Preparation Example 1, and the admixture is a polycarboxylate water reducer.

[0036] Example 3 A centrifugally cast corrosion-resistant concrete pipe, comprising a pipe body and a glass fiber reinforcement cage embedded in the pipe body. The glass fiber reinforcement cage is formed by winding glass fiber bars. The diameter of the glass fiber bars is 7 mm. The glass fiber reinforcement cage is a rhombic grid structure, and the side length of the rhombic grid is 60 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material components and ratios of the corrosion-resistant polymer concrete are shown in Table 1. Among them, the average length of the glass fiber is 20 mm, the solid content of the styrene-acrylic emulsion is 50%, the double-shell structure microcapsules are the double-shell structure microcapsules prepared in Preparation Example 1, and the admixture is a polycarboxylate water reducer.

[0037] Table 1 Raw material components and dosages (kg) of corrosion-resistant polymer concrete

[0038] Example 4 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that in this example, the double-shell structure microcapsules are the double-shell structure microcapsules prepared in Preparation Example 2.

[0039] Example 5 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that in this example, the double-shell structure microcapsules are the double-shell structure microcapsules prepared in Preparation Example 3.

[0040] Comparative Example Comparative Example 1 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that styrene-acrylic emulsion is not added to the raw materials of the corrosion-resistant polymer concrete in this comparative example.

[0041] Comparative Example 2 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that double-shell structure microcapsules are not added to the raw materials of the corrosion-resistant polymer concrete in this comparative example.

[0042] Comparative Example 3 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that single-shell structure microcapsules prepared in Preparation Example 4 are used in equal amounts to replace the double-shell structure microcapsules in this comparative example.

[0043] Comparative Example 4 A centrifugally cast corrosion-resistant concrete pipe, which is different from Example 3 in that single-shell structure microcapsules prepared in Preparation Example 5 are used in equal amounts to replace the double-shell structure microcapsules in this comparative example.

[0044] Performance Detection Test The concrete pipes prepared in the above Examples 1-5 and Comparative Examples 1-4 were subjected to compressive strength detection. According to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009), the RCM method was used for the chloride ion penetration resistance test to measure the chloride ion migration depth, calculate the diffusion coefficient, and conduct the sulfate erosion resistance test. The test results are shown in Table 2.

[0045] Table 2 Detection Results

[0046] The compressive strength of Examples 1-5 is between 130.2-131.8 MPa, and the chloride ion diffusion coefficient is between 1.01×10 −12 −1.07×10 −12 m 2 / s, and the sulfate erosion resistance grades all reach KS150, indicating that the concrete pipes prepared in the examples of this application have stable compressive strength and good corrosion resistance.

[0047] In Comparative Example 1, styrene-acrylic emulsion was not added, and the chloride ion diffusion coefficient was 3.25×10 −12 m 2 / s. Since styrene-acrylic emulsion can form a protective film on the concrete surface to prevent chloride ion penetration, the chloride ion diffusion coefficient increases significantly, and the sulfate erosion resistance grade also decreases to KS90, indicating that adding styrene-acrylic emulsion plays an important role in improving the corrosion resistance of concrete.

[0048] In Comparative Example 2, the double-layer shell structure microcapsules were not added, and the chloride ion diffusion coefficient was 2.94×10 −12 m 2 / s, and the sulfate resistance grade decreased to KS90. Since the core material of the double-layer shell structure microcapsules can fill the pores and enhance the performance of the protective film after release, preventing chloride ion penetration and resisting sulfate erosion, it has a significant effect on improving the corrosion resistance of concrete.

[0049] In Comparative Example 3 and Comparative Example 4, single-layer shell structure microcapsules were used, and the chloride ion diffusion coefficients were 2.33×10 − 12 m 2 / s and 1.98×10 −12 m 2 / s, which were significantly higher than those in Examples 1-5, indicating that the double-layer shell structure microcapsules are more effective in resisting chloride ion penetration. The pH sensitivity of the outer shell enables the core material to be released more precisely, while the single-layer shell structure cannot achieve this function. In Comparative Example 3 and Comparative Example 4, the single-layer shell structure microcapsules were used, and the sulfate resistance grades were also lower than those in Examples 1-5. This is also because the intelligent repair mechanism of the double-layer shell structure microcapsules can more effectively cope with the sulfate erosion environment.

[0050] This specific embodiment is only an explanation of the present application, and it does not limit the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A centrifugally cast corrosion-resistant concrete pipe, characterized in that, It includes a pipe body and a glass fiber rib cage embedded in the pipe body. The pipe body is centrifugally cast from corrosion-resistant polymer concrete, and the corrosion-resistant polymer concrete is made from the following raw materials in parts by weight: 40-50 parts of magnesium phosphate cement; 10-15 parts of fly ash; 5-10 parts of slag powder; 50-70 parts of manufactured sand; 3-5 parts of glass fiber; 10-25 parts of styrene-acrylic emulsion; 10-20 parts of double-shell structure microcapsules; 0.5-1.5 parts of admixture; 20-30 parts of water; The double-shell structure microcapsules include a core material, an inner shell and an outer shell from the inside to the outside. The core material is phenolic resin and nano-titanium dioxide, the inner shell is an epoxy resin-polyamide curing agent copolymer, and the outer shell is a polymethacrylic acid-acrylamide copolymer.

2. The centrifugally cast corrosion-resistant concrete pipe according to claim 1, characterized in that, The double-shell structure microcapsules are prepared by the following method: A. Mix nano-titanium dioxide, liquid phenolic resin and epoxy resin, stir at 60-70 °C for 1-3 h, then perform ultrasonic dispersion for 20-30 min to obtain a core material-epoxy resin mixture. Then add cyclohexane and emulsifier, stir for 20-30 min, and then add polyamide curing agent and stir for 20-30 min to obtain an emulsion; B. Mix methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water to obtain an aqueous solution. Add the emulsion to the aqueous solution, then add ammonium persulfate solution, heat up to 50-60 °C, react for 1-3 h, cool and then centrifuge to separate out the solid product, and then wash and dry the solid product to obtain the double-shell structure microcapsules.

3. The centrifugally cast corrosion-resistant concrete pipe according to claim 2, characterized in that, In step A, the mass ratio of nano-titanium dioxide, liquid phenolic resin and epoxy resin is 1:(5-8):(10-12).

4. The centrifugally cast corrosion-resistant concrete pipe according to claim 3, wherein, In step A, the addition amount of cyclohexane is 30%-50% of epoxy resin, the addition amount of emulsifier is 3%-5% of epoxy resin, and the addition amount of polyamide curing agent is 30%-40% of epoxy resin.

5. A centrifugally cast corrosion-resistant concrete pipe according to claim 4, characterized in that, In step B, the mass ratio of methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water is (1-3):1:(0.02-0.05):(0.05-0.1):(10-15).

6. A centrifugally cast corrosion-resistant concrete pipe according to claim 5, characterized in that, In step B, the mass ratio of the aqueous solution to the emulsion is (3-5):

1.

7. A centrifugally cast corrosion-resistant concrete pipe according to claim 6, wherein, In step B, the mass concentration of the ammonium persulfate solution is 10%-15%, and the addition amount of the ammonium persulfate solution is 3%-5% of the total mass of methacrylic acid and acrylamide.

8. A centrifugally cast corrosion-resistant concrete pipe according to claim 1, characterized in that, The glass fiber rib cage is formed by winding glass fiber ribs. The diameter of the glass fiber ribs is 5-7 mm, and the glass fiber rib cage is a rhombic grid structure with a side length of the rhombic grid of 40-60 mm.

9. The centrifugally cast corrosion-resistant concrete pipe according to claim 1, characterized in that, The solid content of the styrene-acrylic emulsion is 40%-50%.

10. A method for preparing a centrifugally cast corrosion-resistant concrete pipe according to any one of claims 1-9, characterized in that, It includes the following steps: S1. Mix magnesium phosphate cement, fly ash, slag powder, manufactured sand, glass fiber, styrene-acrylic emulsion, double-shell structure microcapsules, admixture and water, and stir for 5-10 min to obtain corrosion-resistant polymer concrete; S2. Place the glass fiber reinforced cage into the mold, then inject corrosion-resistant polymer concrete into the mold for centrifugal molding. After curing and demolding, a centrifugally cast corrosion-resistant concrete pipe is obtained.

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