A centrifugally cast corrosion-resistant concrete pipe and its preparation method

Abstract

This application relates to the field of concrete pipe technology, specifically disclosing a centrifugally cast corrosion-resistant concrete pipe and its preparation method. A centrifugally cast corrosion-resistant concrete pipe includes a pipe body and a fiberglass reinforcement cage embedded within the pipe body. The pipe body is centrifugally cast from corrosion-resistant polymer concrete, which comprises: magnesium phosphate cement, fly ash, slag powder, manufactured sand, fiberglass, styrene-acrylic emulsion, double-shell microcapsules, admixtures, and water. The double-shell microcapsules include a core material, an inner shell, and an outer shell, from the inside out. 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. The concrete pipe of this application exhibits excellent corrosion resistance, and the double-shell microcapsules enable protection and repair of the concrete pipe in corrosive environments.

Description

Technical Field

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

[0002] Concrete pipes, as an important building material, have numerous applications in urban infrastructure construction, industrial production, and water conservancy projects. In municipal engineering, they play a crucial role in water supply and drainage systems. Whether it's the rapid discharge of urban rainwater or the proper collection and transportation of domestic sewage, concrete pipes efficiently complete their tasks, effectively reducing the risk of urban flooding and ensuring the normal operation of residents' lives. In transportation engineering, concrete pipes are used for roadbed drainage in highway and railway construction, ensuring the stability of road structures and extending road lifespan. Furthermore, in scenarios such as irrigation, mine drainage, and chemical wastewater treatment, concrete pipes play an irreplaceable and vital role due to their excellent mechanical properties, high cost-effectiveness, and relatively simple installation process.

[0003] Currently, concrete pipe technology is constantly developing. For example, patent application CN117739176A discloses a steel cylinder concrete pipe and its manufacturing method. This involves sequentially setting several layers of prestressed steel wires on the outside of the pipe core and then placing a prestressed concrete protective layer outside these layers. The prestressed steel wires provide prestress to the concrete pipe, achieving multi-layer winding of prestressed steel wires. This improves the pipe's load-bearing capacity without increasing the pipe wall thickness and solves the problems of protective layer delamination and detachment under high working pressure or deep soil cover. However, in practical applications, existing reinforced concrete pipes still have significant drawbacks. When in corrosive environments, such as industrial wastewater discharge areas or coastal saline-alkali areas, the pipes are highly susceptible to chemical corrosion. Long-term corrosion not only significantly shortens the pipe's service life but also often leads to serious problems such as rusting, cracking, and even leakage.

[0004] A thorough analysis of the root causes of these problems reveals two key issues. First, the concrete used in existing reinforced concrete pipes inherently possesses a porous structure, with interconnected or semi-connected pores providing channels for corrosive media to penetrate, thus resulting in poor corrosion resistance. Second, when corrosive media penetrate into the pipe, the reinforcing steel inside rusts. As corrosion deepens, the mechanical properties of the steel gradually decline, failing to provide sufficient support and constraint for the concrete structure, leading to concrete cracking. Once cracks appear in the concrete, corrosive media can more easily penetrate deeper into the pipe, creating a vicious cycle and accelerating pipe damage. Therefore, effectively improving the corrosion resistance of pipes and overcoming the drawbacks of traditional pipes caused by steel corrosion, thereby reducing maintenance costs and extending the service life of concrete pipes, has become a critical technical challenge that urgently needs to be addressed in the field of concrete pipe technology. Summary of the Invention

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

[0006] This application provides a centrifugally cast corrosion-resistant concrete pipe using the following technical solution:

[0007] A centrifugally cast corrosion-resistant concrete pipe includes a pipe body and a fiberglass reinforcement cage embedded in the pipe body. The pipe body is centrifugally cast from corrosion-resistant polymer concrete, which comprises the following raw materials in parts by weight:

[0008] 40-50 parts of magnesium phosphate cement;

[0009] 10-15 parts fly ash;

[0010] 5-10 parts of slag powder;

[0011] 50-70 parts of manufactured sand;

[0012] 3-5 parts glass fiber;

[0013] 10-25 parts of styrene-acrylic emulsion;

[0014] 10-20 parts of double-shell structured microcapsules;

[0015] 0.5-1.5 parts of admixture;

[0016] 20-30 parts water;

[0017] The double-shell structured microcapsule comprises a core material, an inner shell, and an outer shell, from the inside out. 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.

[0018] By adopting the above technical solution, the pipe body is centrifugally cast using corrosion-resistant polymer concrete. The various raw materials in the corrosion-resistant polymer concrete work synergistically; magnesium phosphate cement, fly ash, slag powder, and manufactured sand form the concrete skeleton; glass fiber enhances toughness and provides excellent water resistance, alkali resistance, and weather resistance. In the concrete, it fills the pores of the magnesium phosphate cement stone, improving the concrete's density and thus enhancing its corrosion resistance. Simultaneously, the polymer molecules in the styrene-acrylic emulsion can form a continuous protective film on the concrete surface, isolating it from external corrosive media. The glass fiber reinforcement cage replaces traditional steel bars, avoiding the problem of steel bar corrosion, significantly improving the pipeline's corrosion resistance, overcoming the drawbacks of traditional steel bars caused by corrosion, extending the pipeline's service life, and reducing maintenance costs.

[0019] By introducing microcapsules with a double-shell structure using phenolic resin and nano-titanium dioxide as the core material, the phenolic resin contains active groups such as hydroxyl and hydroxymethyl groups. When the microcapsules rupture and release the phenolic resin, it can undergo a condensation reaction with the unreacted active groups in the styrene-acrylic resin to form a cross-linked structure. As the reaction proceeds, the phenolic resin gradually solidifies, forming a robust three-dimensional network. This network can grow in the cracks and pores of concrete, filling these defects, improving the density of the concrete, enhancing its impermeability and corrosion resistance, and achieving the repair and protection of 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 reinforcing and filling role, 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 also decompose organic pollutants and some corrosive substances on the concrete surface, reducing their erosion of the concrete, thereby improving the corrosion resistance and durability of the concrete, and achieving the repair and protection of concrete.

[0020] The outer shell, a polymethacrylic acid-acrylamide copolymer, exhibits good pH sensitivity. When concrete pipelines encounter corrosive environments, pH changes cause carboxyl groups on the polymethacrylic acid-acrylamide copolymer molecular chains to protonate, increasing the copolymer's solubility and causing chain extension. This change leads to a looser outer shell structure and alters the interface between the outer and inner shells. 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 polymethacrylic acid-acrylamide copolymer molecular chains of the outer shell extend, the carboxyl groups on these chains react with the active groups of the inner shell, such as through esterification or amidation. These reactions disrupt the inner shell structure, promoting its rupture and accurately releasing the core material's repair particles. By designing a double-shell structure, the mechanical strength of the double-shell structure can be guaranteed, ensuring the microcapsules do not rupture under normal operating conditions such as concrete preparation and transportation. Furthermore, it enables the accurate and rapid release of the core material when the pipeline faces corrosive environments, achieving both repair and protection of the concrete.

[0021] Optionally, the double-shell structured microcapsules are prepared using the following method:

[0022] A. Mix nano-titanium dioxide, liquid phenolic resin and epoxy resin, stir at 60-70℃ for 1-3 hours, then ultrasonically disperse for 20-30 minutes to obtain core material-epoxy resin mixture, then add cyclohexane and emulsifier, stir for 20-30 minutes, then add polyamide curing agent and stir for 20-30 minutes to obtain emulsion.

[0023] B. Aqueous solution is prepared by mixing methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water. Emulsion is added to aqueous solution, followed by ammonium persulfate solution. The temperature is raised to 50-60℃ and the reaction is carried out for 1-3 hours. After cooling, the solid product is separated by centrifugation. The solid product is then washed and dried to obtain double-shell microcapsules.

[0024] By adopting the above technical solution, a method for preparing double-shell microcapsules is provided, which ensures the stability and uniformity of the microcapsule structure. The method employs a two-layer emulsion process, first preparing a core material-epoxy resin emulsion, and then forming the outer shell through interfacial polymerization. This step-by-step process ensures complete encapsulation of the core material and precise molding of the double-shell structure, which is beneficial for improving the performance of the double-shell microcapsules and thus helps enhance the corrosion resistance of corrosion-resistant polymer concrete.

[0025] Optionally, in step A, the mass ratio of nano-titanium dioxide, liquid phenolic resin and epoxy resin is 1:(5-8):(10-12).

[0026] Optionally, in step A, the amount of cyclohexane added is 30%-50% of the epoxy resin, the amount of emulsifier added is 3%-5% of the epoxy resin, and the amount of polyamide curing agent added is 30%-40% of the epoxy resin.

[0027] 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).

[0028] Optionally, in step B, the mass ratio of the aqueous solution to the emulsion is (3-5):1.

[0029] Optionally, in step B, the mass concentration of the ammonium persulfate solution is 10%-15%, and the amount of ammonium persulfate solution added is 3%-5% of the total mass of methacrylic acid and acrylamide.

[0030] By employing the above technical solution, the proportions of raw materials used in microcapsule preparation are precisely controlled, ensuring both 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 possess high mechanical strength, while the outer shell (polymethacrylic acid-acrylamide) precisely responds to corrosive environments. Furthermore, the synergistic reaction between the raw materials enhances the overall performance of the microcapsules.

[0031] Optionally, the fiberglass cage is formed by winding fiberglass reinforcing bars, the diameter of which is 5-7mm, and the fiberglass cage has a diamond-shaped mesh structure with a side length of 40-60mm.

[0032] By adopting the above technical solutions, the shape of the glass fiber reinforced cage is defined. Its rhomboid mesh structure, appropriate spacing and diameter enhance the mechanical properties of the pipeline while avoiding stress concentration that could damage the pipe body. It replaces steel bars to prevent corrosion and works synergistically with corrosion-resistant concrete to improve the overall corrosion resistance of concrete pipelines.

[0033] Optionally, the solid content of the styrene-acrylic emulsion is 40%-50%.

[0034] By adopting the above technical solution, the solid content of 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 concrete's impermeability and corrosion resistance.

[0035] This application also provides a method for preparing centrifugally cast corrosion-resistant concrete pipes, using the following technical solution:

[0036] A method for preparing a centrifugally cast corrosion-resistant concrete pipe includes the following steps:

[0037] S1. Mix magnesium phosphate cement, fly ash, slag powder, manufactured sand, glass fiber, styrene-acrylic emulsion, double-shell microcapsules, admixtures and water, and stir for 5-10 minutes to obtain corrosion-resistant polymer concrete.

[0038] S2. Place the fiberglass reinforcement cage in the mold, then inject corrosion-resistant polymer concrete into the mold for centrifugal molding. After curing and demolding, the centrifugally cast corrosion-resistant concrete pipe is obtained.

[0039] Through standardized pipeline preparation processes, mixing and stirring ensure uniform dispersion of raw materials, centrifugal molding makes the concrete dense and structurally uniform, and curing and demolding processes ensure pipeline strength and dimensional accuracy, thus ensuring the stable production of high-quality corrosion-resistant concrete pipelines.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. This application uses fiberglass reinforced concrete (FRP) cages to replace traditional steel bars and centrifugally casts the pipe body with corrosion-resistant polymer concrete, significantly improving the corrosion resistance of the concrete pipeline. The FRP cages possess excellent corrosion resistance, fundamentally eliminating concrete cracking caused by steel bar corrosion and effectively preventing pipeline damage due to decreased mechanical properties of the steel bars. In the corrosion-resistant polymer concrete, magnesium phosphate cement, fly ash, slag powder, and manufactured sand form a robust skeleton, while fiberglass 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 concrete's density and impermeability. The synergistic effect of these multiple materials comprehensively improves the pipeline's corrosion resistance, extends its service life, reduces maintenance costs, and effectively solves the problem of poor durability of traditional reinforced concrete pipelines in corrosive environments.

[0042] 2. This application introduces a double-shell microcapsule structure with phenolic resin and nano-titanium dioxide as the core material, achieving intelligent repair and improved corrosion resistance of concrete pipelines. When the pipeline encounters corrosion, the polymethacrylic acid-acrylamide copolymer on the outer layer of the microcapsule undergoes protonation due to changes in environmental pH, increasing its solubility, extending its molecular chains, and loosening its structure. It then undergoes esterification or amidation reactions with the inner shell, causing the inner shell to rupture and precisely releasing the core material. The unreacted active groups in the phenolic resin and styrene-acrylic resin condense to form a robust three-dimensional network that fills cracks and pores. Nano-titanium dioxide enhances the protective film's performance through physical adsorption and decomposes organic pollutants and corrosive substances on the concrete surface through photocatalysis. This intelligent repair mechanism can respond promptly to corrosion damage to the pipeline, effectively repairing the concrete structure and further enhancing the pipeline's corrosion resistance and durability.

[0043] 3. This application clarifies the preparation method and raw material ratio of the double-shell microcapsule structure, and standardizes the preparation process of concrete pipes, ensuring the stability and reliability of product quality. Precise microcapsule preparation technology and raw material ratios ensure that the inner shell has sufficient mechanical strength to withstand external forces during concrete preparation and transportation, while simultaneously enabling the outer shell to possess precise pH sensitivity, achieving accurate release of the core material. Standardized pipe preparation processes ensure uniform dispersion of concrete raw materials and a dense and uniform pipe structure, thereby stably producing high-quality corrosion-resistant concrete pipes and ensuring the consistency and stability of product performance. Attached Figure Description

[0044] Figure 1 The infrared spectrum of the double-shell microcapsule prepared in Example 1. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments.

[0046] Example of preparation of double-shell structured microcapsules

[0047] Preparation Example 1

[0048] The double-shell structured microcapsules were prepared using the following method:

[0049] A. Mix 1 kg of nano titanium dioxide, 5 kg of liquid phenolic resin and 10 kg of epoxy resin E51, stir at 60℃ and 300 rpm for 1 h, then ultrasonically disperse at an ultrasonic frequency of 40 kHz for 20 min to obtain a core material-epoxy resin mixture. Next, add 3 kg of cyclohexane and 0.3 kg of emulsifier, stir at 10000 rpm for 20 min, then add 3 kg of polyamide 650 curing agent, and continue stirring at 10000 rpm for 20 min to obtain an emulsion.

[0050] 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 phase solution. Add the emulsion to the aqueous phase solution at a mass ratio of 3:1, and then add 0.06 kg of 10% ammonium persulfate solution. Heat to 50°C and react for 1 h. Nitrogen gas is introduced for protection during the reaction. After the reaction is completed, cool to room temperature and separate the solid product by centrifugation. Wash the solid product three times with deionized water and anhydrous ethanol, respectively. Then dry it in a vacuum drying oven at 40°C for 6 h to obtain a double-shell microcapsule.

[0051] Preparation Example 2

[0052] The double-shell structured microcapsules were prepared using the following method:

[0053] 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℃ and 300 rpm for 2 h, then ultrasonically disperse at 35 kHz for 25 min to obtain a core material-epoxy resin mixture. Next, add 4.4 kg of cyclohexane and 0.44 kg of emulsifier, stir at 10000 rpm for 25 min, then add 3.85 kg of polyamide 650 curing agent, and continue stirring at 10000 rpm for 25 min to obtain an emulsion.

[0054] B. Aqueous solution was prepared by mixing 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. Emulsion was added to the aqueous solution at a mass ratio of 4:1, followed by 0.12 kg of 12% ammonium persulfate solution. The mixture was heated to 55°C and reacted for 2 h under nitrogen protection. After the reaction, the mixture was cooled to room temperature and the solid product was separated by centrifugation. The solid product was washed three times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 40°C for 6 h to obtain double-shell microcapsules.

[0055] Preparation Example 3

[0056] The double-shell structured microcapsules were prepared using the following method:

[0057] A. Mix 1 kg of nano titanium dioxide, 8 kg of liquid phenolic resin and 12 kg of epoxy resin E51, stir at 70℃ and 300 rpm for 3 h, then ultrasonically disperse at 30 kHz for 30 min to obtain a core material-epoxy resin mixture. Next, add 6 kg of cyclohexane and 0.6 kg of emulsifier, stir at 10000 rpm for 30 min, then add 4.8 kg of polyamide 650 curing agent, and continue stirring at 10000 rpm for 30 min to obtain an emulsion.

[0058] 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 phase solution. Add the emulsion to the aqueous phase solution at a mass ratio of 5:1, and then add 0.2 kg of 15% ammonium persulfate solution. Heat to 60°C and react for 3 h, with nitrogen gas purging during the reaction. After the reaction, cool to room temperature and separate the solid product by centrifugation. Wash the solid product three times with deionized water and anhydrous ethanol, and then dry it in a vacuum drying oven at 40°C for 6 h to obtain a double-shell microcapsule.

[0059] Preparation Example 4

[0060] Single-shell microcapsules, with a core material of phenolic resin and nano-titanium dioxide, and an outer shell of epoxy resin-polyamide curing agent copolymer, were prepared using the following method:

[0061] A. Mix 1 kg of nano titanium dioxide, 8 kg of liquid phenolic resin and 12 kg of epoxy resin E51, stir at 70℃ and 300 rpm for 3 h, then ultrasonically disperse at 30 kHz for 30 min to obtain a core material-epoxy resin mixture. Next, add 6 kg of cyclohexane and 0.6 kg of emulsifier, stir at 10000 rpm for 30 min, then add 4.8 kg of polyamide 650 curing agent, and continue stirring at 10000 rpm for 30 min to obtain an emulsion.

[0062] B. The emulsion was heated to 45°C and reacted for 3 hours. Nitrogen gas was introduced for protection during the reaction. After the reaction was completed, the mixture was cooled to room temperature and the solid product was separated by centrifugation. The solid product was washed three times with deionized water and anhydrous ethanol, respectively. Then, it was dried in a vacuum drying oven at 40°C for 6 hours to obtain a single-shell microcapsule with an epoxy resin-polyamide curing agent copolymer as the outer shell.

[0063] Preparation Example 5

[0064] Single-shell microcapsules, with a core material of phenolic resin and nano-titanium dioxide, and an outer shell of polymethacrylic acid-acrylamide copolymer, were prepared using the following method:

[0065] A. Add 1 kg of nano-titanium dioxide and 8 kg of liquid phenolic resin to 6 kg of cyclohexane, stir at 70℃ and 300 rpm for 3 h, and then disperse by ultrasonication 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 and 15 kg of deionized water to form an aqueous phase solution, and add the core material dispersion to the aqueous phase solution under stirring at 10000 rpm, and continue stirring for 30 min to form an emulsion;

[0066] B. Add 0.2 kg of 15% ammonium persulfate solution to the emulsion, purge with nitrogen for protection, heat to 60°C and react for 3 h, purge with nitrogen during the reaction, cool to room temperature after the reaction is complete, 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 a single-shell structure microcapsule with polymethacrylic acid-acrylamide copolymer as the outer shell.

[0067] Example

[0068] Example 1

[0069] A centrifugally cast corrosion-resistant concrete pipe includes a pipe body and a fiberglass reinforcement cage embedded in the pipe body. The fiberglass reinforcement cage is formed by winding fiberglass bars with a diameter of 5 mm. The fiberglass reinforcement cage has a rhomboid mesh structure with a side length of 40 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material composition and formula of the corrosion-resistant polymer concrete are shown in Table 1. The average length of the fiberglass is 20 mm, the solid content of the styrene-acrylic emulsion is 40%, the double-shell microcapsules are selected from those prepared in Example 1, and the admixture is a polycarboxylate superplasticizer.

[0070] Example 2

[0071] A centrifugally cast corrosion-resistant concrete pipe includes a pipe body and a fiberglass reinforcement cage embedded in the pipe body. The fiberglass reinforcement cage is formed by winding fiberglass bars with a diameter of 6 mm. The fiberglass reinforcement cage has a rhomboid mesh structure with a side length of 50 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material composition and formula of the corrosion-resistant polymer concrete are shown in Table 1. The average length of the fiberglass is 20 mm, the solid content of the styrene-acrylic emulsion is 45%, the double-shell microcapsules are selected from those prepared in Example 1, and the admixture is a polycarboxylate superplasticizer.

[0072] Example 3

[0073] A centrifugally cast corrosion-resistant concrete pipe includes a pipe body and a fiberglass reinforcement cage embedded in the pipe body. The fiberglass reinforcement cage is formed by winding fiberglass bars with a diameter of 7 mm. The fiberglass reinforcement cage has a rhomboid mesh structure with a side length of 60 mm. The pipe body is centrifugally cast from corrosion-resistant polymer concrete. The raw material composition and formula of the corrosion-resistant polymer concrete are shown in Table 1. The average length of the fiberglass is 20 mm, the solid content of the styrene-acrylic emulsion is 50%, the double-shell microcapsules are selected from those prepared in Example 1, and the admixture is a polycarboxylate superplasticizer.

[0074] Table 1. Raw material composition and dosage (kg) of corrosion-resistant polymer concrete

[0075]

[0076] Example 4

[0077] The centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that the double-shell structure microcapsules in this example are the double-shell structure microcapsules prepared in Preparation Example 2.

[0078] Example 5

[0079] The centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that the double-shell structure microcapsules in this example are the double-shell structure microcapsules prepared in Example 3.

[0080] Comparative Example

[0081] Comparative Example 1

[0082] A centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that no styrene-acrylic emulsion is added to the corrosion-resistant polymer concrete raw materials in this comparative example.

[0083] Comparative Example 2

[0084] A centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that the corrosion-resistant polymer concrete raw material in this comparative example does not contain double-shell microcapsules.

[0085] Comparative Example 3

[0086] A centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that an equal amount of single-shell microcapsules prepared in Preparation Example 4 are used instead of double-shell microcapsules in this comparative example.

[0087] Comparative Example 4

[0088] A centrifugally cast corrosion-resistant concrete pipe differs from Example 3 in that an equal amount of single-shell microcapsules prepared in Preparation Example 5 are used instead of double-shell microcapsules in this comparative example.

[0089] Performance testing

[0090] The concrete pipes prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to compressive strength testing. According to the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2009), chloride ion penetration resistance tests were conducted using the RCM method to measure chloride ion migration depth and calculate diffusion coefficients. Sulfate erosion resistance tests were also performed. The test results are shown in Table 2.

[0091] Table 2 Detection Results

[0092]

[0093] The compressive strength of Examples 1-5 is between 130.2 and 131.8 MPa, and the chloride ion diffusion coefficient is 1.01 × 10⁻⁶. −12 -1.07×10 −12 m 2The concrete pipes prepared in this application have stable compressive strength and good corrosion resistance, with a strength between 0.5 and 0.5, and their sulfate resistance rating reaches KS150.

[0094] Comparative Example 1, without the addition of styrene-acrylic emulsion, had a chloride ion diffusion coefficient of 3.25 × 10⁻⁶. −12 m 2 / s, because styrene-acrylic emulsion can form a protective film on the concrete surface, preventing chloride ion penetration, thus leading to a significant increase in the chloride ion diffusion coefficient and a decrease in the sulfate attack resistance level to KS90. This indicates that the addition of styrene-acrylic emulsion plays an important role in improving the corrosion resistance of concrete.

[0095] Comparative Example 2, without the addition of double-shell microcapsules, had a chloride ion diffusion coefficient of 2.94 × 10⁻⁶. −12 m 2 / s, the sulfate resistance rating is reduced to KS90. Because the core material of the double-shell microcapsules, once released, can fill pores, enhance the protective film performance, prevent chloride ion penetration, and resist sulfate attack, it has a significant effect on improving the corrosion resistance of concrete.

[0096] Comparative Examples 3 and 4 used single-shell microcapsules, with chloride ion diffusion coefficients of 2.33 × 10⁻⁶ and 2.33 × 10⁻⁶, respectively. − 12 m 2 / s and 1.98×10 −12 m 2 The pH value was significantly higher than that of Examples 1-5, indicating that the double-shell microcapsules are more effective in resisting chloride ion penetration. The pH sensitivity of the outer shell allows for more precise release of the core material, a function that a single-shell structure cannot achieve. Comparative Examples 3 and 4, which used single-shell microcapsules, also showed lower sulfate resistance than Examples 1-5, again because the intelligent repair mechanism of the double-shell microcapsules is more effective in dealing with sulfate-eroded environments.

[0097] 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 centrifugally cast corrosion-resistant concrete pipe, characterized in that, The system includes a pipe body and a fiberglass reinforcement cage embedded within the pipe body. The pipe body is constructed by centrifugal casting of corrosion-resistant polymer concrete, which comprises the following raw materials in parts by weight: 40-50 parts of magnesium phosphate cement; 10-15 parts fly ash; 5-10 parts of slag powder; 50-70 parts of manufactured sand; 3-5 parts glass fiber; 10-25 parts of styrene-acrylic emulsion; 10-20 parts of double-shell structured microcapsules; 0.5-1.5 parts of admixture; 20-30 parts water; The double-shell structured microcapsule comprises a core material, an inner shell, and an outer shell, from the inside out. 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 structured microcapsules were prepared using the following method: A. Mix nano-titanium dioxide, liquid phenolic resin and epoxy resin, stir at 60-70℃ for 1-3 hours, then ultrasonically disperse for 20-30 minutes to obtain core material-epoxy resin mixture, then add cyclohexane and emulsifier, stir for 20-30 minutes, then add polyamide curing agent and stir for 20-30 minutes to obtain emulsion. B. Aqueous solution is prepared by mixing methacrylic acid, acrylamide, N,N'-methylenebisacrylamide, sodium dodecylbenzenesulfonate and deionized water. Emulsion is added to aqueous solution, followed by ammonium persulfate solution. The temperature is raised to 50-60℃ and the reaction is carried out for 1-3 hours. After cooling, the solid product is separated by centrifugation. The solid product is then washed and dried to obtain double-shell 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. A centrifugally cast corrosion-resistant concrete pipe according to claim 3, characterized in that, In step A, the amount of cyclohexane added is 30%-50% of the epoxy resin, the amount of emulsifier added is 3%-5% of the epoxy resin, and the amount of polyamide curing agent added is 30%-40% of the 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, characterized in that, In step B, the mass concentration of the ammonium persulfate solution is 10%-15%, and the amount of ammonium persulfate solution added 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 fiberglass cage is formed by winding fiberglass reinforcing bars, the diameter of which is 5-7mm. The fiberglass cage has a diamond-shaped mesh structure with a side length of 40-60mm.

9. A 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, The steps include the following: S1. Mix magnesium phosphate cement, fly ash, slag powder, manufactured sand, glass fiber, styrene-acrylic emulsion, double-shell microcapsules, admixtures and water, and stir for 5-10 minutes to obtain corrosion-resistant polymer concrete. S2. Place the fiberglass reinforcement cage in the mold, then inject corrosion-resistant polymer concrete into the mold for centrifugal molding. After curing and demolding, the centrifugally cast corrosion-resistant concrete pipe is obtained.

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