Anti-fatigue concrete sleeper and preparation method thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to an anti-fatigue concrete sleeper and a preparation method thereof. The anti-fatigue concrete sleeper comprises a concrete sleeper body and reinforcing steel bars arranged in the concrete sleeper body, the concrete sleeper body is formed by solidifying a concrete material, and the concrete material comprises cement, fly ash, silica fume, aggregate, an additive, fibers, a resin-based material, a curing agent and water. Through resin compounding and fiber component design, the concrete sleeper forms multiple anti-fatigue mechanisms under repeated dynamic loads; organic silicon modified epoxy resin and acrylic acid modified polyurethane resin are adopted to toughen the concrete sleeper, rigid support of a three-dimensional net structure is reserved, energy buffering is achieved through a flexible molecular chain, and stress concentration under repeated load of a train is reduced; by adjusting a curing system, the curing temperature of the resin material is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and in particular relates to an anti-fatigue concrete sleeper and a preparation method thereof. Background Art

[0002] Sleepers are crucial components of railway track structures, supporting rails, maintaining track gauge, and transferring train loads to the trackbed. They reduce vibration and impact during train operation, improving ride comfort. Compared to traditional wooden sleepers, concrete sleepers offer a longer service life, greater stability, lower maintenance requirements, and lower damage and scrap rates. They have become a crucial component in modern railway construction.

[0003] The pressure applied to the rails when a train passes changes dynamically, causing the sleepers to be constantly affected by complex stress states such as compression and bending. This is especially true on high-speed railways and heavy-load transport routes, where the dynamic loads borne by the sleepers are more significant due to the high traffic density and high axle load. In order to ensure the stability and safety of the track geometry, the sleepers are required to maintain their mechanical properties for a long time without significant deterioration, which places higher demands on the fatigue resistance of the sleepers. Currently, there are two types of concrete sleepers: ordinary reinforced concrete sleepers and prestressed reinforced concrete sleepers. Ordinary concrete sleepers have obvious deficiencies in overall bending resistance, impact resistance, and fatigue resistance. They have poor bending resistance and fatigue resistance under train load impact, and the concrete structure of the end sleepers is easily damaged and cracked. At the same time, since the end shoulder is a plain concrete structure without steel reinforcement, the shoulder has poor crack resistance and is prone to cracks and concrete falling, which in turn affects the strength of the track bed structure. However, the inherent brittleness of existing prestressed concrete means it can crack at any time when subjected to repeated loads. This is especially true when prestress loss exceeds a certain limit, reducing the effective prestress within the sleeper and potentially leading to premature fatigue damage. Furthermore, the tensioning of prestressed steel bars requires strict quality control. Inaccurate tensioning force, loose anchoring, or poor concrete pouring quality, including defects such as holes and honeycombs, can all negatively impact the sleeper's fatigue resistance.

[0004] Chinese patent application document with publication number CN113620669A discloses a concrete sleeper comprising PO42.5 silicate cement, a composite admixture, fine aggregate, a first coarse aggregate, a second coarse aggregate, a water reducer, and mixing water. The patent application further specifies that the particle size range of the first coarse aggregate is 5-10 mm, the particle size range of the second coarse aggregate is 10-20 mm, and both the first coarse aggregate and the second coarse aggregate are coarse aggregates of continuous particle size. The composite admixture comprises fly ash, limestone powder, and pyrite cinder. The mass percentages of the fly ash, limestone powder, and pyrite cinder in the composite admixture are 30%-40%, 40%-50%, and 10%-30%, respectively. This concrete sleeper improves the compressive strength and elastic modulus of concrete through particle grading and admixture content design, but the cement content in its formula is relatively high, releasing a large amount of heat during hydration. The sleeper is small in volume and has poor heat dissipation, which easily forms an internal and external temperature difference and causes temperature cracks. The pyrite slag in the composite admixture contains impurities such as sulfide and free calcium oxide. The sulfide can react with water in the concrete to generate acidic substances, destroying the passivation film of the steel bars and accelerating steel corrosion. The free calcium oxide will hydrate and expand in the later stage of cement hydration, resulting in poor volume stability of the concrete. Summary of the Invention

[0005] In order to solve the technical problems of cracking, poor volume stability and poor fatigue resistance of concrete sleepers in the above-mentioned prior art, the present invention provides a fatigue-resistant concrete sleeper and a preparation method thereof.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: A fatigue-resistant concrete sleeper comprises a concrete sleeper and a steel bar arranged inside the concrete sleeper. The concrete sleeper is formed by solidifying a concrete material. The concrete material comprises the following components in parts by mass: 200-300 parts of cement, 20-30 parts of fly ash, 10-20 parts of silica fume, 280-320 parts of aggregate, 10-20 parts of admixture, 25-40 parts of fiber, 15-20 parts of resin-based material, 5-10 parts of curing agent, and 70-90 parts of water; The resin-based material is composed of modified epoxy resin and modified polyurethane resin in a mass ratio of 11-15:4-8. The modified epoxy resin is an organosilicon-modified epoxy resin, and the modified polyurethane resin is an acrylic acid-modified polyurethane resin.

[0007] The present invention forms multiple anti-fatigue mechanisms for concrete sleepers under repeated dynamic loads through resin compounding and fiber component design. Cement and mineral admixtures synergistically improve the gel strength, improve the brittleness of concrete, and reduce shrinkage cracks. Among them, the compounding of silicone-modified epoxy resin and acrylic acid-modified polyurethane resin not only retains the high strength of epoxy resin and the rigid support of the three-dimensional network structure, but also realizes energy buffering through the flexible molecular chain of acrylic acid-modified polyurethane. Under repeated train loads, the flexible chain segments can absorb impact energy through deformation, reducing the damage to the cement matrix caused by stress concentration. In addition, after curing, the resin-based material can fill the pores inside the concrete, and while reducing the porosity of the concrete, it can form a dense interface with the cement hydration product. The polar groups in the resin interact with the hydroxyl groups on the surface of the aggregate and the CaCl2+ of the cement hydration product. 2+ It forms hydrogen bonds or coordination bonds, eliminates the loose defects in the traditional interface transition zone, significantly improves the density of concrete sleepers, and cooperates with cement and mineral admixtures to jointly improve the compressive strength and flexural strength to meet the sleeper's requirements for bearing capacity.

[0008] Furthermore, the preparation method of the modified epoxy resin is as follows: dissolving 1-allyloxy-2,3-propylene oxide in toluene, adding a catalyst and 1,1,3,3-tetraethyldisiloxane under the protection of an inert gas, heating the reaction, cooling, and rotary evaporation to obtain a toughening agent; mixing the toughening agent, bisphenol A epoxy resin, and toluene, and stirring evenly to obtain a modified epoxy resin.

[0009] The present invention adopts 1-allyloxy-2,3-propylene oxide and 1,1,3,3-tetraethyldisiloxane through a hydrosilylation reaction to prepare a toughening agent containing both rigid epoxy groups and flexible segments in the molecule, and modifies bisphenol A epoxy resin. The molecular chain of the siloxane segment in the toughening agent can rotate freely, and the siloxane bond can generate silanol groups through hydrolysis, forming hydrogen bonds with hydroxyl groups on the surface of the aggregate. The epoxy group can react with the oxide layer on the surface of the steel bar to enhance the interfacial bonding strength between the steel bar and the concrete. When the modified epoxy resin is mixed with concrete, the flexible segments are uniformly dispersed in the concrete matrix to form a composite structure of rigid epoxy network + flexible siloxane. Under repeated dynamic loads of the train, the flexible segments in the composite structure undergo elastic deformation to achieve a balance between strength and toughness. At the same time, the rigid epoxy network maintains the strength of the matrix, avoids plastic damage caused by excessive deformation, and improves the fatigue resistance of the concrete sleeper.

[0010] Furthermore, the mass parts of each component in the preparation method of the modified epoxy resin are: 50-60 parts of 1-allyloxy-2,3-propylene oxide, 2-5 parts of catalyst, 30-40 parts of 1,1,3,3-tetraethyldisiloxane, and 100-120 parts of bisphenol A epoxy resin.

[0011] Furthermore, in the preparation method of the modified epoxy resin, the catalyst is a platinum catalyst; the temperature of the temperature-raising reaction is 85-90° C., and the temperature-raising reaction time is 24-30 hours.

[0012] Furthermore, the preparation method of the modified polyurethane resin is as follows: dehydrated polyoxyethylene glycol is mixed with toluene diisocyanate, the temperature is raised to 70-80°C, the reaction is carried out for 3-4 hours, hydroxyethyl acrylate is added, the reaction is continued for 1-2 hours, the temperature is lowered to 45°C, acrylic acid and triethylamine are added, the reaction is stirred for 0.5-1 hour, deionized water is added, potassium persulfate is added after stirring evenly, the temperature is raised to 90-100°C, the reaction is kept warm for 3-4 hours, and reduced pressure distillation is performed to obtain the modified polyurethane resin.

[0013] In the present invention, polyoxyethylene glycol, toluene diisocyanate cyanoethyl acrylate are used as the main raw materials to synthesize waterborne polyurethane prepolymer, and then through chain extension, cross-linking, acrylic acid modification and other reactions, a modified polyurethane resin is prepared. By grafting acrylate segments onto the polyurethane resin segments, a certain rigidity is provided to the polyurethane resin, forming a rigid-flexible alternating network structure with the flexible polyurethane segments. In the concrete sleeper, the stress can be dispersed by segment slippage and stretching, thereby improving the toughness of the concrete. At the same time, the polar groups in the modified polyurethane resin molecules can react with cement hydration products, Ca 2+ Form hydrogen bonds or coordination bonds, improve interface bonding strength, optimize interface performance, and improve the fatigue resistance of concrete sleepers.

[0014] Furthermore, the mass parts of each component in the preparation method of the modified polyurethane resin are: 80-90 parts of polyoxyethylene glycol, 35-50 parts of toluene diisocyanate, 10-15 parts of hydroxyethyl acrylate, 10-15 parts of acrylic acid, 5-8 parts of triethylamine, and 3-5 parts of potassium persulfate.

[0015] Furthermore, the curing agent is composed of diethylenetriamine, dibutyltin dilaurate and semicarbazide in a mass ratio of 8-11:5-9:2-5.

[0016] In the present invention, diethylenetriamine, dibutyltin dilaurate and semicarbazide are used to form a curing system. Diethylenetriamine has strong nucleophilicity and high reactivity with the epoxy group of the modified epoxy resin, thereby effectively reducing the curing temperature of the modified epoxy resin. Dibutyltin dilaurate can activate the -NCO group in the modified polyurethane resin through coordination, thereby reducing the reaction temperature of the curing reaction. Semicarbazide has high reactivity with the -NCO group at room temperature, thereby realizing room-temperature curing of the modified polyurethane resin.

[0017] Furthermore, the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 2-4:5-9; the coarse aggregate is crushed stone of continuous particle size with a particle size range of 5-20 mm; the fine aggregate is machine-made sand of continuous particle size with a fineness modulus of 3.0.

[0018] Furthermore, the admixture is composed of a polycarboxylic acid high-performance water-reducing agent and a defoaming agent in a mass ratio of 10-12:3-5; the water reduction rate of the polycarboxylic acid high-performance water-reducing agent is 25%-30%, and the defoaming agent is polydimethylsiloxane.

[0019] In the present invention, the addition of a polycarboxylic acid high-performance water-reducing agent during the concrete mixing process can not only achieve efficient dispersion of cement particles, reduce the water-cement ratio, and improve the density of the concrete, but also prevent cement particles from agglomerating through steric hindrance, so that the cement forms a more uniform and dense interface transition zone on the aggregate surface; the defoaming agent can reduce the amount of bubbles generated during the concrete mixing process, improve the homogeneity of the concrete, and enhance the impermeability and durability of the concrete.

[0020] Furthermore, the fiber is one of carbon fiber, basalt fiber and glass fiber.

[0021] The present invention also provides a method for preparing the above-mentioned fatigue-resistant concrete sleeper, which is specifically: Mix cement, fly ash, silica fume, aggregate and water, add admixture, stir for 5-10 minutes, then continue to add resin, materials and curing agent, stir for 10-20 minutes, add fiber, stir for 5-10 minutes, pour into a sleeper mold with steel bars, vibrate on a vibration table for 2-5 minutes, demould after curing for 1 day, heat to 60-80℃ for steam curing at a heating rate of 10-15℃ / h, cool at a cooling rate of 5-10℃ / h to obtain fatigue-resistant concrete sleepers.

[0022] During the preparation process of the concrete sleeper of the present invention, the heating rate and cooling rate of steam curing are strictly controlled to avoid excessive heating rate, which increases internal defects of the concrete sleeper and reduces fatigue resistance, and excessive cooling rate, which accumulates residual stress and aggravates fatigue damage.

[0023] Compared with the prior art, the fatigue-resistant concrete sleeper and the preparation method thereof provided by the present invention have the following technical advantages: (1) The present invention, through resin compounding and fiber component design, enables the concrete sleeper to form multiple anti-fatigue mechanisms under repeated dynamic loads. Cement and mineral admixtures synergistically improve the gel strength, improve the brittleness of concrete, and reduce shrinkage cracks. (2) The present invention uses silicone-modified epoxy resin and acrylic acid-modified polyurethane resin to toughen concrete sleepers, which not only retains the rigid support of the three-dimensional network structure, but also achieves energy buffering through flexible molecular chains, reducing stress concentration under repeated train loads; (3) In the present invention, diethylenetriamine, dibutyltin dilaurate and semicarbazide are used to form a curing system, which effectively reduces the curing temperature of the resin material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the H NMR spectrum of the toughening agent in the modified epoxy resin prepared in Example 4; Figure 2 This is the infrared spectrum of the modified polyurethane resin obtained in Example 4. DETAILED DESCRIPTION

[0025] The following will be further described in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art may make various modifications based on the basic concept of the present invention, but as long as they do not depart from the basic concept of the present invention, they are all within the scope of the present invention.

[0026] Unless otherwise specified, the raw materials described in this embodiment are commercially available. The cement described in this embodiment is P·O 52.5 Portland cement; the molecular weight of the polyoxyethylene glycol described in the preparation method of the modified polyurethane resin is 1000-2000; the coarse aggregate is continuously graded crushed stone with a particle size range of 5-20 mm; and the fine aggregate is continuously graded machine-made sand with a fineness modulus of 3.0.

[0027] Preparation Example 1 The preparation method of the modified epoxy resin is as follows: 50g of 1-allyloxy-2,3-propylene oxide is dissolved in 150mL of dry toluene and stirred evenly; under nitrogen protection, 2g of platinum catalyst and 40g of 1,1,3,3-tetraethyldisiloxane are added; the temperature is raised to 85°C for reaction for 30h; the mixture is cooled to room temperature; the temperature is raised to 80°C for rotary evaporation to obtain a toughening agent; the toughening agent, 100g of bisphenol A epoxy resin and 50mL of toluene are mixed and stirred evenly to obtain a modified epoxy resin.

[0028] Preparation Example 2 The preparation method of the modified epoxy resin is as follows: 60g of 1-allyloxy-2,3-propylene oxide is dissolved in 150mL of dry toluene and stirred evenly; under nitrogen protection, 5g of platinum catalyst and 30g of 1,1,3,3-tetraethyldisiloxane are added; the temperature is raised to 90°C for reaction for 24h; the temperature is cooled to room temperature; the temperature is raised to 80°C for rotary evaporation to obtain a toughening agent; the toughening agent, 120g of bisphenol A epoxy resin and 50mL of toluene are mixed and stirred evenly to obtain a modified epoxy resin.

[0029] Preparation Example 3 The preparation method of the modified epoxy resin is as follows: 58g of 1-allyloxy-2,3-propylene oxide is dissolved in 150mL of dry toluene and stirred evenly; under nitrogen protection, 4g of platinum catalyst and 36g of 1,1,3,3-tetraethyldisiloxane are added; the temperature is raised to 88°C for reaction for 28h; the temperature is cooled to room temperature; the temperature is raised to 80°C for rotary evaporation to obtain a toughening agent; the toughening agent, 110g of bisphenol A epoxy resin and 50mL of toluene are mixed and stirred evenly to obtain a modified epoxy resin.

[0030] Preparation Example 4 The preparation method of the modified polyurethane resin is as follows: 80g of polyoxyethylene glycol is added to a four-necked flask, dehydrated at 100°C and a vacuum degree of -0.09MPa for 2h, cooled to 70°C, added with 35g of toluene diisocyanate, kept warm for reaction for 3h, added with 10g of hydroxyethyl acrylate, continued to react for 1h, cooled to 45°C, added with 10g of acrylic acid and 5g of triethylamine, stirred for reaction for 0.5h, added with 55g of deionized water, stirred at a speed of 1000rpm for 10min, added with 3g of potassium persulfate, heated to 90°C, kept warm for reaction for 3h, and distilled under reduced pressure at 40°C and -0.08MPa to obtain the modified polyurethane resin.

[0031] Preparation Example 5 The preparation method of the modified polyurethane resin is as follows: 90g of polyoxyethylene glycol is added to a four-necked flask, dehydrated at 120°C and a vacuum degree of -0.09MPa for 3h, cooled to 80°C, added with 50g of toluene diisocyanate, kept warm for reaction for 4h, added with 15g of hydroxyethyl acrylate, continued to react for 2h, cooled to 45°C, added with 15g of acrylic acid and 8g of triethylamine, stirred for reaction for 1h, added with 45g of deionized water, stirred at a speed of 1200rpm for 15min, added with 5g of potassium persulfate, heated to 100°C, kept warm for reaction for 4h, and distilled under reduced pressure at 50°C and -0.08MPa to obtain the modified polyurethane resin.

[0032] Preparation Example 6 The preparation method of the modified polyurethane resin is as follows: 86g of polyoxyethylene glycol is added to a four-necked flask, dehydrated at 115°C and a vacuum degree of -0.09MPa for 2.5h, cooled to 75°C, added with 42g of toluene diisocyanate, kept warm for reaction for 3.5h, added with 13g of hydroxyethyl acrylate, continued to react for 1.5h, cooled to 45°C, added with 13g of acrylic acid and 7g of triethylamine, stirred for reaction for 0.8h, added with 50g of deionized water, stirred at a speed of 1100rpm for 13min, added with 4g of potassium persulfate, heated to 95°C, kept warm for reaction for 3.5h, and distilled under reduced pressure at 45°C and -0.08MPa to obtain the modified polyurethane resin.

[0033] Example 1 A fatigue-resistant concrete sleeper comprises a concrete sleeper and steel bars arranged inside the concrete sleeper. The concrete sleeper is formed by solidifying concrete material. The concrete material comprises the following components in parts by mass: 200 parts cement, 30 parts fly ash, 20 parts silica fume, 280 parts aggregate, 10 parts admixture, 25 parts basalt fiber, 15 parts resin-based material, 5 parts curing agent, and 70 parts water; the resin-based material is composed of modified epoxy resin and modified polyurethane resin in a mass ratio of 11:4. The modified epoxy resin is prepared according to Preparation Example 1, and the modified polyurethane resin is prepared according to Preparation Example 4.

[0034] The curing agent is composed of diethylenetriamine, dibutyltin dilaurate and semicarbazide in a mass ratio of 8:5:2; the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 2:5; the admixture is composed of polycarboxylic acid high-performance water reducer and polydimethylsiloxane in a mass ratio of 10:3; the water reduction rate of the polycarboxylic acid high-performance water reducer is 25%.

[0035] The preparation method of the fatigue-resistant concrete sleeper is specifically as follows: Cement, fly ash, silica fume, aggregate and water are mixed, admixtures are added, and the mixture is stirred for 5 minutes. Then, resin, materials and curing agent are added and stirred for 10 minutes. Fiber is added and stirred for 5 minutes. The mixture is poured into a sleeper mold with steel bars and vibrated on a compaction table for 2 minutes. After curing for 1 day, the mixture is demoulded and heated to 60°C for steam curing at a heating rate of 10°C / h. The mixture is cooled at a cooling rate of 5°C / h to obtain fatigue-resistant concrete sleepers.

[0036] Example 2 A fatigue-resistant concrete sleeper comprises a concrete sleeper and steel bars arranged inside the concrete sleeper. The concrete sleeper is formed by solidifying concrete material. The concrete material comprises the following components in parts by mass: 300 parts of cement, 20 parts of fly ash, 10 parts of silica fume, 320 parts of aggregate, 20 parts of admixture, 40 parts of glass fiber, 20 parts of resin-based material, 10 parts of curing agent, and 90 parts of water; the resin-based material is composed of modified epoxy resin and modified polyurethane resin in a mass ratio of 15:8; the modified epoxy resin is prepared by Preparation Example 2, and the modified polyurethane resin is prepared by Preparation Example 5.

[0037] The curing agent is composed of diethylenetriamine, dibutyltin dilaurate and semicarbazide in a mass ratio of 11:9:5; the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 4:9; the admixture is composed of polycarboxylic acid high-performance water reducer and polydimethylsiloxane in a mass ratio of 12:5; the water reduction rate of the polycarboxylic acid high-performance water reducer is 30%.

[0038] The preparation method of the fatigue-resistant concrete sleeper is specifically as follows: Cement, fly ash, silica fume, aggregate and water are mixed, admixtures are added, and the mixture is stirred for 10 minutes. Then, resin, materials and curing agent are added and stirred for 20 minutes. Fiber is added and stirred for 10 minutes. The mixture is poured into a sleeper mold with steel bars and vibrated on a compaction table for 5 minutes. After curing for 1 day, the mixture is demoulded and heated to 80°C for steam curing at a heating rate of 15°C / h. The mixture is cooled at a cooling rate of 10°C / h to obtain fatigue-resistant concrete sleepers.

[0039] Example 3 A fatigue-resistant concrete sleeper comprises a concrete sleeper and steel bars arranged inside the concrete sleeper. The concrete sleeper is formed by solidifying concrete material. The concrete material comprises the following components in parts by mass: 260 parts cement, 27 parts fly ash, 15 parts silica fume, 300 parts aggregate, 17 parts admixture, 32 parts carbon fiber, 18 parts resin-based material, 8 parts curing agent, and 85 parts water; the resin-based material is composed of modified epoxy resin and modified polyurethane resin in a mass ratio of 13:6. The modified epoxy resin is prepared according to Preparation Example 3, and the modified polyurethane resin is prepared according to Preparation Example 6.

[0040] The curing agent is composed of diethylenetriamine, dibutyltin dilaurate and semicarbazide in a mass ratio of 9:7:4; the aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 3:7; the admixture is composed of polycarboxylic acid high-performance water reducer and polydimethylsiloxane in a mass ratio of 11:4; the water reduction rate of the polycarboxylic acid high-performance water reducer is 28%.

[0041] The preparation method of the fatigue-resistant concrete sleeper is specifically as follows: Cement, fly ash, silica fume, aggregate and water were mixed, admixtures were added, and the mixture was stirred for 8 minutes. Then, resin, materials and curing agent were added and stirred for 15 minutes. Fiber was added and stirred for 8 minutes. The mixture was poured into a sleeper mold with steel bars and vibrated on a compaction table for 4 minutes. After curing for 1 day, the mixture was demoulded and heated to 70°C for steam curing at a heating rate of 13°C / h. The mixture was cooled at a cooling rate of 8°C / h to obtain fatigue-resistant concrete sleepers.

[0042] Example 4 The fatigue-resistant concrete sleeper and its preparation method in this embodiment are similar to those in Example 3. The difference between this embodiment and Example 3 is that the resin-based material in this embodiment is composed of a modified epoxy resin and a modified polyurethane resin in a mass ratio of 12:7. The modified epoxy resin is prepared according to Preparation Example 3, and the modified polyurethane resin is prepared according to Preparation Example 6.

[0043] Comparative Example 1 The concrete sleepers and their preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that the resin-based materials in this comparative example are all modified epoxy resins, and the modified epoxy resins are prepared by Preparation Example 3.

[0044] Comparative Example 2 The concrete sleepers and their preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that the resin-based materials in this comparative example are all modified polyurethane resins, and the modified polyurethane resins are prepared by Preparation Example 6.

[0045] Comparative Example 3 The concrete sleeper and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that this comparative example uses an equal amount of bisphenol A epoxy resin instead of modified epoxy resin.

[0046] Comparative Example 4 The concrete sleeper and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of polyurethane resin is used instead of modified polyurethane resin in this comparative example. The preparation method of the polyurethane resin is as follows: 86 g of polyoxyethylene glycol is added to a four-necked flask, dehydrated at 115° C. and a vacuum degree of -0.09 MPa for 2.5 hours, cooled to 75° C., added 42 g of toluene diisocyanate, and kept warm for reaction for 3.5 hours, added 13 g of hydroxyethyl acrylate, continued to react for 1.5 hours, cooled to 45° C., added 13 g of deionized water and 7 g of triethylamine, stirred for reaction for 0.8 hours, added 50 g of deionized water, stirred at a rotation speed of 1100 rpm for 13 minutes, added 4 g of potassium persulfate, heated to 95° C., kept warm for reaction for 3.5 hours, and distilled under reduced pressure at 45° C. and -0.08 MPa to obtain a polyurethane resin.

[0047] Comparative Example 5 The concrete sleeper and the preparation method thereof in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that the mass ratio of the modified epoxy resin to the modified polyurethane resin in this comparative example is 2:7.

[0048] Comparative Example 6 The concrete sleeper and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that the curing agent in this comparative example is composed of dibutyltin dilaurate and semicarbazide in a mass ratio of 5:1.

[0049] Test example Mechanical properties test: According to GB / T 50081-2019, the compressive strength and elastic modulus of the concrete sleepers prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were tested. The test results are shown in Table 1.

[0050] Durability test: According to GB / T 50082-2024, the durability test was carried out on the concrete sleepers prepared in Examples 1 to 4 and Comparative Examples 1 to 6. The test results are shown in Table 2.

[0051] Fatigue resistance test: A fatigue testing machine was used to test the crack resistance of the concrete sleepers prepared in Examples 1 to 4 during fatigue. The load cycle characteristic Q = 0.2 was used. The maximum loaded column width, maximum loaded column height, remaining maximum column width, and remaining maximum column height were measured when Pmax = 220 kN, Pmin = 44 kN, and the number of fatigue cycles was 200. The number of cracks was recorded. The test results are shown in Table 3.

[0052] Table 1 Mechanical properties test results

[0053] Table 2 Durability test results

[0054] As can be seen from Table 1, the elastic modulus of the concrete sleeper provided by the present invention is 40.3-43.2 GPa, the 3d compressive strength is 41.5-45.5 MPa, the 7d compressive strength is 65.2-69.5 MPa, and the 28d compressive strength is 84.6-90.1 MPa, which shows that the concrete sleeper provided by the present invention has good mechanical properties and high elasticity, and can be used in rail transportation such as railways to better buffer and conduct rail vibrations.

[0055] As can be seen from Table 2, the aluminum ion diffusion coefficient of the concrete sleeper provided by the present invention is 2.9-3.2, the electric flux is 568-586C, P=84.9%-89.8% and ΔW=0.8%-1.2% after 300 freeze-thaw cycles, which shows that the concrete sleeper provided by the present invention has good freeze-thaw resistance and good durability.

[0056] Compared with Example 4, the resin-based materials in Comparative Example 1 are all modified epoxy resins, but the elastic modulus of the prepared concrete sleeper is reduced and the durability is poor. This shows that the modified polyurethane resin can form a rigid-flexible alternating network structure through its flexible segments, thereby improving the toughness of the concrete sleeper; in Comparative Example 2, the resin-based materials are all modified polyurethane resins, and in Comparative Example 3, an equal amount of bisphenol A epoxy resin is used instead of the modified epoxy resin, but the elastic modulus and compressive strength of the prepared concrete sleeper are reduced to varying degrees, and the durability is poor. This shows that the modified epoxy resin can not only improve the toughness of concrete, but also improve the mechanical properties of concrete. Although the unmodified epoxy resin can ensure the mechanical properties of the concrete sleeper, its elastic modulus is significantly reduced; in Comparative Example 4, acrylic acid is not used to modify the polyurethane resin, but the obtained The compressive strength of the concrete sleeper is significantly reduced and the durability is deteriorated, which shows that the use of acrylic acid to modify the polyurethane resin can effectively improve the rigidity of the polyurethane resin, so that it forms a rigid and flexible network structure in the concrete sleeper, and improves the elastic modulus and compressive strength of the concrete sleeper; in Comparative Example 5, the mass ratio of the modified epoxy resin and the modified polyurethane resin was changed, but the elastic modulus and compressive strength of the prepared concrete sleeper were reduced to varying degrees, and the durability was deteriorated, which shows that the modified epoxy resin and the modified polyurethane resin in the present invention have a synergistic effect; in Comparative Example 6, the type and dosage ratio of the curing agent were changed, and the elastic modulus and compressive strength of the prepared concrete sleeper were reduced to varying degrees, and the durability was deteriorated. This is because the change in the curing agent component and dosage leads to a deterioration in the curing effect of the modified epoxy resin and the modified polyurethane resin.

[0057] Table 3 Fatigue resistance test results

[0058] It can be seen from Table 3 that the concrete sleeper provided by the present invention has a maximum loaded column width of 0.020-0.040 mm, a remaining maximum column width of 0.015-0.025 mm, a maximum loaded column height of 20-28 mm, a remaining maximum column height of 8-13 mm, and a number of cracks of 0-2 under the conditions of load cycle characteristics Q=0.2, Pmax=220 kN, Pmin=44 kN, and fatigue times of 200 times. This fully demonstrates that the concrete sleeper provided by the present invention has good load fatigue resistance.

[0059] In addition, the present invention also conducted a nuclear magnetic hydrogen spectrum test on the toughening agent prepared in the preparation method of the modified epoxy resin in Example 4, and the test results are shown in FIG. Figure 1 .Depend on Figure 1It can be seen that the epoxy group has been incorporated into the silicone through the hydrosilylation reaction between 1-allyloxy-2,3-epoxypropylene and 1,1,3,3-tetraethyldisiloxane, which indicates that a hydrosilylation reaction has occurred between 1-allyloxy-2,3-epoxypropylene and 1,1,3,3-tetraethyldisiloxane.

[0060] The present invention also conducted infrared spectrum test on the modified polyurethane resin prepared in Example 4, and the test results are shown in FIG. Figure 2 .Depend on Figure 2 It can be seen that at 3310cm -1 and 1172cm -1 There are absorption peaks of -NH and C=O at 1125 cm -1 The stretching vibration peak of COC appears at 1230 cm -1 The characteristic peak of polyacrylic acid appeared at , which shows that the preparation of modified polyurethane resin was successful.

[0061] The above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Persons skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. Any equivalent modifications or alterations made by persons skilled in the art without departing from the technical spirit of the present invention are intended to fall within the scope of protection of the present invention.

Claims

1. A fatigue-resistant concrete sleeper, characterized in that: The concrete sleeper comprises a concrete sleeper and a steel bar arranged inside the concrete sleeper. The concrete sleeper is formed by solidifying a concrete material. The concrete material comprises the following components in parts by mass: 200-300 parts of cement, 20-30 parts of fly ash, 10-20 parts of silica fume, 280-320 parts of aggregate, 10-20 parts of admixture, 25-40 parts of fiber, 15-20 parts of resin-based material, 5-10 parts of curing agent, and 70-90 parts of water; The resin-based material is composed of modified epoxy resin and modified polyurethane resin in a mass ratio of 11-15:4-8. The modified epoxy resin is an organosilicon-modified epoxy resin, and the modified polyurethane resin is an acrylic acid-modified polyurethane resin.

2. The anti-fatigue concrete sleeper according to claim 1, characterized in that: The preparation method of the modified epoxy resin comprises the following steps: dissolving 1-allyloxy-2,3-propylene oxide in toluene, adding a catalyst and 1,1,3,3-tetraethyldisiloxane under the protection of an inert gas, heating the mixture for reaction, cooling the mixture, and rotary evaporating the mixture to obtain a toughening agent; and mixing the toughening agent, bisphenol A epoxy resin, and toluene, stirring the mixture uniformly, and obtaining the modified epoxy resin.

3. The anti-fatigue concrete sleeper according to claim 2, characterized in that: The mass parts of the components in the preparation method of the modified epoxy resin are: 50-60 parts of 1-allyloxy-2,3-epoxypropane, 2-5 parts of a catalyst, 30-40 parts of 1,1,3,3-tetraethyldisiloxane and 100-120 parts of a bisphenol A epoxy resin.

4. The anti-fatigue concrete sleeper according to claim 2, characterized in that: The catalyst is a platinum catalyst; the temperature of the temperature-raising reaction is 85-90° C., and the time of the temperature-raising reaction is 24-30 hours.

5. The anti-fatigue concrete sleeper according to claim 1, characterized in that: The preparation method of the modified polyurethane resin comprises the following steps: mixing dehydrated polyoxyethylene glycol and toluene diisocyanate, heating the mixture to 70-80° C., reacting the mixture for 3-4 hours, adding hydroxyethyl acrylate, continuing the reaction for 1-2 hours, cooling the mixture to 45° C., adding acrylic acid and triethylamine, stirring the mixture for 0.5-1 hour, adding deionized water, stirring the mixture evenly, adding potassium persulfate, heating the mixture to 90-100° C., keeping the temperature for reaction for 3-4 hours, and performing reduced pressure distillation to obtain the modified polyurethane resin.

6. The anti-fatigue concrete sleeper according to claim 5, characterized in that: The mass parts of the components in the preparation method of the modified polyurethane resin are: 80-90 parts of polyoxyethylene glycol, 35-50 parts of toluene diisocyanate, 10-15 parts of hydroxyethyl acrylate, 10-15 parts of acrylic acid, 5-8 parts of triethylamine and 3-5 parts of potassium persulfate.

7. The anti-fatigue concrete sleeper according to claim 1, characterized in that: The curing agent is composed of diethylenetriamine, dibutyltin dilaurate and semicarbazide in a mass ratio of 8-11:5-9:2-5.

8. The anti-fatigue concrete sleeper according to claim 1, characterized in that: The aggregate is composed of coarse aggregate and fine aggregate in a mass ratio of 2-4:5-9; the coarse aggregate is crushed stone of continuous particle size with a particle size range of 5-20 mm; the fine aggregate is machine-made sand of continuous particle size with a fineness modulus of 3.

0.

9. The anti-fatigue concrete sleeper according to claim 1, characterized in that: The admixture is composed of a polycarboxylic acid high-performance water-reducing agent and a defoaming agent in a mass ratio of 10-12:3-5; the water reduction rate of the polycarboxylic acid high-performance water-reducing agent is 25%-30%, the defoaming agent is polydimethylsiloxane; and the fiber is one of carbon fiber, basalt fiber, and glass fiber.

10. The method for preparing the fatigue-resistant concrete sleeper according to any one of claims 1 to 9, characterized in that: Specifically: Mix cement, fly ash, silica fume, aggregate and water, add admixture, stir for 5-10 minutes, then continue to add resin, materials and curing agent, stir for 10-20 minutes, add fiber, stir for 5-10 minutes, pour into a sleeper mold with steel bars, vibrate on a vibration table for 2-5 minutes, demould after curing for 1 day, heat to 60-80℃ for steam curing at a heating rate of 10-15℃ / h, cool at a cooling rate of 5-10℃ / h to obtain fatigue-resistant concrete sleepers.

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