A type of concrete for wind turbine towers and its preparation method

Abstract

This invention provides a concrete for wind turbine towers and its preparation method, belonging to the field of building materials technology. The method includes the following steps: Methyl laurate and methyl palmitate are thoroughly mixed, then dried diatomaceous earth is added and vacuum impregnated to obtain a composite phase change material; SiO2-modified ethyl cellulose is added to anhydrous ethanol and ultrasonically treated, then the composite phase change material is added, mixed, stirred, filtered, and vacuum dried to obtain a microcapsule composite phase change material; zinc phosphate, phosphoric acid, water, KH560, and cobalt-modified biochar are mixed and stirred, then pretreated steel fibers are added and impregnated, ultrasonically treated and continuously stirred, and dried to obtain surface-modified steel fibers; sand and gravel aggregates, cement, surface-modified steel fibers, microcapsule composite phase change material, mineral admixtures, additives, and water are mixed evenly to obtain concrete for wind turbine towers. This invention can improve the mechanical strength and corrosion resistance of concrete while also improving its freeze-thaw resistance.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a type of concrete for wind turbine towers and its preparation method. Background Technology

[0002] With the increasing global demand for renewable energy, wind power has become a core component of green energy. Its high efficiency, cleanliness, and sustainability make it an important means of addressing climate change and environmental issues. As a key component of wind power systems, wind turbine towers not only need to withstand the immense pressure of wind but also face the challenges of various extreme environments. Wind turbine towers are typically installed in locations with unique climatic conditions, such as coastal areas, high-altitude and frigid regions, and mountainous areas. The natural environmental factors in these areas pose significant challenges to the long-term operation and structural stability of wind turbine towers, thus requiring high-quality materials for the concrete used in the tower casing.

[0003] While concrete, as a key structural material for wind turbine towers, possesses a certain strength, its brittle nature makes it prone to cracking during long-term use, leading to a decline in durability. Especially under extreme climatic conditions, the brittleness of concrete becomes more pronounced. Particularly in cold regions, when the concrete of wind turbine towers undergoes periodic freeze-thaw cycles, the internal moisture freezes and expands in the pores, then shrinks upon thawing, causing cracks in the concrete and directly affecting the structural safety of the wind turbine tower. In addition, wind turbine towers are typically exposed to harsh environmental conditions, subjected to long-term erosion by salt spray, moisture, and acidic rainwater. Chlorides and acidic substances in salt spray and moisture can penetrate into the concrete, corroding the steel fibers. After corrosion, the steel fibers expand, leading to cracks in the concrete. These cracks not only reduce the compressive strength of the concrete but also significantly decrease its physical and mechanical properties, thus affecting the structural stability of the wind turbine tower. Furthermore, wind turbine towers are constantly exposed to wind and vibration environments. The periodic vibration of the wind generates internal stress within the wind turbine tower structure, which also requires the concrete used for wind turbine towers to have good mechanical properties.

[0004] Therefore, there is a need to provide concrete for wind turbine towers and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of this, the present invention provides concrete for wind turbine towers and its preparation method, which can improve the mechanical strength and corrosion resistance of concrete while improving its freeze-thaw resistance.

[0006] To achieve the above objectives, the present invention provides a method for preparing concrete for wind turbine towers, comprising the following steps:

[0007] S1. By mass, 20-30 parts of methyl lauryl ester and 10-15 parts of methyl palmitate are thoroughly mixed, and then 30 parts of dried diatomaceous earth are added. The mixture is then vacuum impregnated to obtain a composite phase change material. 2-5 parts of SiO2-modified ethyl cellulose are added to anhydrous ethanol and ultrasonically treated. Then, 30-40 parts of the composite phase change material are added, mixed, stirred, filtered, and vacuum dried to obtain a microcapsule composite phase change material.

[0008] S2. By weight, mix 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 5-8 parts KH560, and 0.5-3 parts cobalt-modified biochar material, then add pretreated steel fibers for impregnation, ultrasonically treat and continuously stir, and dry to obtain surface-modified steel fibers.

[0009] S3. By weight, mix 1000-1200 parts of sand and gravel aggregate, 800-900 parts of cement, 150-200 parts of surface-modified steel fiber, 10-30 parts of microcapsule composite phase change material, 160-200 parts of mineral admixture, 17-25 parts of additives and 150-220 parts of water to prepare concrete for wind turbine towers.

[0010] This invention employs microencapsulation technology to prepare microcapsule composite phase change materials. The composite phase change material is obtained by encapsulating diatomaceous earth loaded with methyl laurate and methyl palmitate using SiO2-modified ethyl cellulose. This results in finer surface pores in the diatomaceous earth, preventing the desorption and exudation of methyl laurate and methyl palmitate within the diatomaceous earth. This avoids impacting the loading efficiency of the diatomaceous earth and the subsequent excessive exudation of methyl laurate and methyl palmitate on the subsequent hydration process of the concrete used in wind turbine towers, thereby affecting the overall freeze-thaw resistance and mechanical strength. The microcapsule composite phase change material can absorb / release latent heat at the phase change point, delaying supercooling or superheating of the matrix to reduce the overall thermal and cold loads of the concrete material. When the temperature decreases, the microcapsule composite phase change material releases latent heat, slowing down the rate of temperature drop within the entire structure, delaying the occurrence of supercooling in the matrix, mitigating crack propagation caused by extreme temperature changes, effectively improving overall freeze-thaw resistance, extending building life, and reducing maintenance costs.

[0011] In addition, the nano-silica in SiO2-modified ethyl cellulose forms a rigid skeleton, which provides mechanical support and can also disperse certain stress, further improving the overall durability and mechanical properties; the nano-silica particles increase the density of the matrix and participate in the cement hydration process around the fiber, which significantly improves the overall adhesive performance of the material.

[0012] This invention improves the overall compressive strength of concrete by incorporating surface-modified steel fibers, while simultaneously allowing the fibers to act as bridges between surrounding cracks in the concrete matrix, thus reducing crack formation. Furthermore, this invention, through cobalt-modified biochar material combined with surface phosphorylation, endows the steel fibers with excellent corrosion resistance and strong bonding strength with the matrix. The Co in the cobalt-modified biochar material... 2+ / Co 3+ Redox reactions catalyze phosphate conversion, accelerating the formation of a denser passivation layer on the steel fiber surface, further isolating it from corrosive substances and water erosion. In addition, the addition of cobalt-modified biochar material increases the surface roughness of the steel fiber, resulting in stronger mechanical interlocking between the steel fiber and the cement paste in the concrete matrix, thereby improving the interfacial bonding strength and further reducing crack formation.

[0013] Optionally, the composite phase change material is obtained by thoroughly mixing methyl laurate and methyl palmitate, adding dried diatomaceous earth, and impregnating it under vacuum at 30°C and -0.1MPa for 24 hours; the dried diatomaceous earth is obtained by drying diatomaceous earth at 60~70°C for 16~24 hours.

[0014] Diatomaceous earth itself has a rich microporous structure and a large specific surface area. This invention utilizes a vacuum impregnation method to allow methyl laurate and methyl palmitate to fully enter and be vacuum adsorbed into the pore structure of diatomaceous earth, forming a composite phase change material with a high specific surface area, which can store and release heat more efficiently.

[0015] Optionally, the SiO2-modified ethyl cellulose is prepared by mixing 20 parts by mass of modified ethyl cellulose and 20-50 parts by mass of a 5% nano-silica suspension, stirring at 50°C for 3-5 hours, filtering, washing with deionized water 2-5 times, and vacuum drying at 60-80°C for 8-12 hours.

[0016] The modified ethyl cellulose is prepared by adding 10 parts by weight of ethyl cellulose to 50 parts by weight of a 30% aqueous solution of terminal amino hyperbranched polyamide, mixing and stirring at 100-140°C for 6-10 hours, filtering, washing with deionized water 2-5 times, and vacuum drying at 60-80°C for 8-12 hours.

[0017] This invention uses amino-terminated hyperbranched polyamide to modify ethyl cellulose, thereby achieving the formation of a rigid framework by grafting nano-silica onto the surface, which effectively reduces the impact of the composite phase change material on the overall mechanical strength.

[0018] Optionally, in step S1, the ultrasonic treatment time is 10-15 min, the mixing and stirring time is 30 min, and the vacuum drying temperature is 60-80℃ and the time is 8-12 h.

[0019] Optionally, the cobalt-modified biochar material is prepared by adding 10-15 parts by weight of rice straw powder and 20-40 parts by weight of cobalt sulfate heptahydrate to 100 parts by weight of deionized water, ultrasonically treating for 30-50 minutes, mixing and stirring for 1-2 hours, drying in an oven at 60°C for 12-16 hours, and then pyrolyzing at high temperature in a muffle furnace at 600°C for 3 hours.

[0020] The rice straw powder is obtained by washing rice straw with water, drying it in an oven at 60°C for 24 hours, and then processing it into fine powder using a mixer.

[0021] This invention utilizes the pyrolysis of rice straw at high temperatures to form biochar, thus realizing the utilization of renewable resources. Cobalt sulfate heptahydrate provides cobalt ions to form cobalt oxides or other compounds during the pyrolysis process, which are uniformly distributed on the surface of the biochar.

[0022] Optionally, the pretreated steel fibers are prepared by sequentially rinsing the steel fibers with acetone and deionized water, acid washing with a 10% sulfuric acid solution at 60°C for 3-5 minutes, and rinsing with deionized water.

[0023] This invention uses rinsing to remove residual grease and surface contaminants from steel fibers, and acid pickling to provide a suitable basis for the nucleation of subsequent phosphate coatings.

[0024] Optionally, in step S2, the mixing and stirring time is 10-15 min, the impregnation temperature is 40℃-65℃ and the time is 20-30 min, the ultrasonic treatment and continuous stirring time is 30-50 min, and the drying time is 24-36 h.

[0025] Optionally, in step S3, 10-15 parts by weight of recycled tire rubber particles are added and mixed with sand and gravel aggregate, cement, surface-modified steel fiber, microcapsule composite phase change material, mineral admixture, additives and water to prepare concrete for wind turbine towers.

[0026] The recycled tire rubber granules are made from crushed waste tires.

[0027] Preferably, the recycled tire rubber granules are black, irregular granules with a particle size of approximately 1.0 mm.

[0028] This invention incorporates recycled tire rubber particles into the preparation of concrete for wind turbine towers, enabling the recycling of waste tire rubber. When the concrete is subjected to external forces, the flexibility of the recycled tire rubber particles can reduce the stress directly acting on the concrete matrix, thereby reducing the occurrence of cracks.

[0029] Optionally, the mineral admixture is silica fume and fly ash, and the additives are polycarboxylate superplasticizer and sodium gluconate retarder.

[0030] The present invention also provides a concrete for wind turbine towers, which is prepared using the above-described method for preparing concrete for wind turbine towers.

[0031] The present invention uses the above-mentioned proportions to better utilize the comprehensive performance of the concrete for wind turbine towers.

[0032] The above-described technical solution of the present invention has at least the following beneficial effects:

[0033] 1. This invention prepares microencapsulated composite phase change materials using microencapsulation technology. By encapsulating diatomaceous earth loaded with methyl laurate and methyl palmitate using SiO2-modified ethyl cellulose, the resulting composite phase change material exhibits finer surface pores in the diatomaceous earth. This prevents desorption and exudation of the phase change material within the diatomaceous earth, avoiding negative impacts on the loading efficiency of the diatomaceous earth and the subsequent hydration process of the concrete used in wind turbine towers due to excessive exudation of methyl laurate and methyl palmitate, which in turn affects the overall freeze-thaw resistance and mechanical strength. This material can absorb / release latent heat at the phase change point, regulating temperature changes, slowing down the cooling rate, delaying the supercooling state, and enhancing freeze-thaw resistance.

[0034] 2. In this invention, nano-silica in SiO2-modified ethyl cellulose is used as a rigid skeleton to provide mechanical support, effectively disperse stress, and thus enhance the durability and mechanical properties of the composite material.

[0035] 3. This invention improves the compressive strength of concrete and reduces crack formation by incorporating surface-modified steel fibers. At the same time, it combines cobalt-modified biochar materials with phosphorylation treatment to give the steel fibers good corrosion resistance and bonding strength. Cobalt ions promote phosphate conversion, accelerate the formation of a passivation layer on the surface of the steel fibers, enhance corrosion resistance and improve interfacial bonding, and reduce crack formation. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0037] Example 1

[0038] 60 parts of diatomaceous earth were dried at 70℃ for 24 hours to obtain dried diatomaceous earth. 30 parts of methyl lauryl acid and 15 parts of methyl palmitate were thoroughly mixed, and then 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1 MPa vacuum for 24 hours to obtain a composite phase change material. 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide. The mixture was stirred at 130℃ for 8 hours, filtered, washed four times with deionized water, and then dried under vacuum at 70℃ for 9 hours to obtain modified ethyl cellulose. Cellulose; 20 parts of modified ethyl cellulose and 50 parts of nano silica suspension with a mass concentration of 5% were mixed and stirred at 50℃ for 4 h. After filtration, the mixture was washed 5 times with deionized water and vacuum dried at 70℃ for 10 h to obtain SiO2-modified ethyl cellulose; 5 parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 15 min. Then, 40 parts of composite phase change material were added and mixed and stirred for 30 min. After filtration, the mixture was vacuum dried at 80℃ for 12 h to obtain microcapsule composite phase change material.

[0039] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. Ten parts of rice straw fine powder and 40 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 50 minutes, mixed and stirred for 2 hours, dried in an oven at 60℃ for 16 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then subjected to a mass concentration [unspecified] at 60℃. Pretreated steel fibers were obtained by acid washing with 10% sulfuric acid solution for 5 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 8 parts KH560 (CAS: 2530-83-8), and 3 parts cobalt-modified biochar material were mixed and stirred for 15 min. The pretreated steel fibers were then added and impregnated at 65℃ for 25 min. The mixture was ultrasonically treated and stirred continuously for 50 min. Finally, it was dried at room temperature for 30 h to obtain surface-modified steel fibers.

[0040] 1200 parts of sand and gravel aggregate, 15 parts of recycled tire rubber granules, 900 parts of cement, 200 parts of surface-modified steel fiber, 30 parts of microencapsulated composite phase change material, 140 parts of silica fume, 60 parts of fly ash, 15 parts of polycarboxylate superplasticizer, 10 parts of sodium gluconate retarder, and 220 parts of water were mixed and stirred evenly to prepare concrete for wind turbine towers. Among them, the recycled tire rubber granules were processed from waste rubber tires and were black irregular particles with a particle size of about 1.0 mm.

[0041] Example 2

[0042] 60 parts of diatomaceous earth were dried at 65℃ for 24 hours to obtain dried diatomaceous earth; 20 parts of methyl laurate and 10 parts of methyl palmitate were thoroughly mixed, and then 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1MPa vacuum for 24 hours to obtain a composite phase change material; 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, mixed and stirred at 100℃ for 6 hours, filtered, washed twice with deionized water, and dried under vacuum at 65℃ for 10 hours to obtain modified ethyl cellulose. SiO2-modified ethyl cellulose was prepared by mixing 20 parts of modified ethyl cellulose and 30 parts of nano-silica suspension with a mass concentration of 5%, stirring at 50°C for 3.5 h, filtering, washing three times with deionized water, and vacuum drying at 65°C for 8 h. Four parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 15 min. Then, 40 parts of composite phase change were added, mixed and stirred for 30 min, filtered, and vacuum dried at 80°C for 12 h to obtain microcapsule composite phase change material.

[0043] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. 15 parts of rice straw fine powder and 40 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 50 minutes, mixed and stirred for 2 hours, dried in an oven at 60℃ for 16 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then processed at 60℃ with a mass concentration of [missing information]. Pretreated steel fibers were obtained by acid washing with 10% sulfuric acid solution for 5 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 8 parts KH560 (CAS: 2530-83-8), and 1.5 parts cobalt-modified biochar material were mixed and stirred for 15 min. The pretreated steel fibers were then added and impregnated at 65℃ for 30 min. The mixture was ultrasonically treated and stirred continuously for 50 min. Finally, it was dried at room temperature for 36 h to obtain surface-modified steel fibers.

[0044] 1200 parts of sand and gravel aggregate, 15 parts of recycled tire rubber granules, 900 parts of cement, 200 parts of surface-modified steel fiber, 20 parts of microencapsulated composite phase change material, 120 parts of silica fume, 50 parts of fly ash, 15 parts of polycarboxylate superplasticizer, 7 parts of sodium gluconate retarder, and 200 parts of water were mixed and stirred evenly to prepare concrete for wind turbine towers. Among them, the recycled tire rubber granules were processed from waste rubber tires and were black irregular particles with a particle size of about 1.0 mm.

[0045] Example 3

[0046] 60 parts of diatomaceous earth were dried at 70℃ for 16 hours to obtain dried diatomaceous earth; 28 parts of methyl lauryl acid and 15 parts of methyl palmitate were thoroughly mixed, and then 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1MPa vacuum for 24 hours to obtain a composite phase change material; 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, and the mixture was stirred at 100℃ for 6 hours. After filtration, the mixture was washed twice with deionized water and dried under vacuum at 70℃ for 8 hours to obtain modified ethyl cellulose. Cellulose; 20 parts of modified ethyl cellulose and 20 parts of nano-silica suspension with a mass concentration of 5% were mixed and stirred at 50℃ for 3h. After filtration, the mixture was washed twice with deionized water and dried under vacuum at 60℃ for 8h to obtain SiO2-modified ethyl cellulose; 2 parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 10min. Then, 30 parts of composite phase change material were added and mixed and stirred for 30min. After filtration, the mixture was dried under vacuum at 60℃ for 12h to obtain microcapsule composite phase change material.

[0047] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. 12 parts of rice straw fine powder and 25 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 30 minutes, mixed and stirred for 1 hour, dried in an oven at 60℃ for 12 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then subjected to a solution with a mass concentration of [missing information - likely a specific concentration]. Pretreated steel fibers were obtained by acid washing with 10% sulfuric acid solution for 4 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 5 parts KH560 (CAS: 2530-83-8), and 0.5 parts cobalt-modified biochar material were mixed and stirred for 10 min. The pretreated steel fibers were then added and impregnated at 45℃ for 20 min. The mixture was ultrasonically treated and stirred continuously for 30 min. Finally, it was dried at room temperature for 24 h to obtain surface-modified steel fibers.

[0048] 1000 parts of sand and gravel aggregate, 10 parts of recycled tire rubber granules, 800 parts of cement, 150 parts of surface-modified steel fiber, 12 parts of microencapsulated composite phase change material, 100 parts of silica fume, 40 parts of fly ash, 12 parts of polycarboxylate superplasticizer, 5 parts of sodium gluconate retarder, and 150 parts of water are mixed and stirred evenly to prepare concrete for wind turbine towers. Among them, the recycled tire rubber granules are black irregular particles with a particle size of about 1.0 mm, which are made by crushing and processing waste rubber tires.

[0049] Example 4

[0050] 60 parts of diatomaceous earth were dried at 70℃ for 18 hours to obtain dried diatomaceous earth; 25 parts of methyl lauryl acid and 15 parts of methyl palmitate were thoroughly mixed, and 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1MPa vacuum for 24 hours to obtain a composite phase change material; 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, mixed and stirred at 120℃ for 8 hours, filtered, washed three times with deionized water, and dried under vacuum at 65℃ for 10 hours to obtain modified ethyl cellulose. SiO2-modified ethyl cellulose was prepared by adding 20 parts of modified ethyl cellulose to 35 parts of nano-silica suspension with a mass concentration of 5% and stirring at 50°C for 4.5 h, filtering, washing 4 times with deionized water, and vacuum drying at 75°C for 11 h; 3 parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 12 min, then 38 parts of composite phase change material were added and mixed and stirred for 30 min, filtered, and vacuum dried at 75°C for 10 h.

[0051] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. 14 parts of rice straw fine powder and 40 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 40 minutes, mixed and stirred for 2 hours, dried in an oven at 60℃ for 15 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then subjected to a mass concentration [unspecified] at 60℃. Pretreated steel fibers were obtained by acid washing with 10% sulfuric acid solution for 4 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 7 parts KH560 (CAS: 2530-83-8), and 3 parts cobalt modified biochar material were mixed and stirred for 12 min. The pretreated steel fibers were then added and impregnated at 60℃ for 25 min. The mixture was ultrasonically treated and stirred continuously for 45 min. Finally, it was dried at room temperature for 30 h to obtain surface-modified steel fibers.

[0052] 1100 parts of sand and gravel aggregate, 12 parts of recycled tire rubber granules, 820 parts of cement, 170 parts of surface-modified steel fiber, 15 parts of microencapsulated composite phase change material, 110 parts of silica fume, 50 parts of fly ash, 12 parts of polycarboxylate superplasticizer, 6 parts of sodium gluconate retarder, and 170 parts of water were mixed and stirred evenly to prepare concrete for wind turbine towers. Among them, the recycled tire rubber granules were processed from waste rubber tires and were black irregular particles with a particle size of about 1.0 mm.

[0053] Example 5

[0054] 65 parts of diatomaceous earth were dried at 60℃ for 24 hours to obtain dried diatomaceous earth; 25 parts of methyl lauryl acid and 10 parts of methyl palmitate were thoroughly mixed, and then 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1MPa vacuum for 24 hours to obtain a composite phase change material; 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, mixed and stirred at 140℃ for 10 hours, filtered, washed four times with deionized water, and dried under vacuum at 80℃ for 12 hours to obtain modified ethyl cellulose. SiO2-modified ethyl cellulose was prepared by mixing 20 parts of modified ethyl cellulose and 50 parts of nano-silica suspension with a mass concentration of 5%, stirring at 50°C for 5 hours, filtering, washing three times with deionized water, and vacuum drying at 80°C for 12 hours. 5 parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 12 minutes. Then, 35 parts of composite phase change material were added, mixed and stirred for 30 minutes, filtered, and vacuum dried at 70°C for 12 hours to obtain microcapsule composite phase change material.

[0055] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. 12 parts of rice straw fine powder and 40 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 40 minutes, mixed and stirred for 1.5 hours, dried in an oven at 60℃ for 16 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then subjected to a mass concentration [unspecified] at 60℃. Pretreated steel fibers were obtained by pickling with 10% sulfuric acid solution for 5 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 8 parts KH560 (CAS: 2530-83-8), and 2.5 parts cobalt-modified biochar material were mixed and stirred for 13 min. The pretreated steel fibers were then added and impregnated at 65℃ for 25 min. The mixture was ultrasonically treated and stirred continuously for 35 min. Finally, it was dried at room temperature for 28 h to obtain surface-modified steel fibers.

[0056] 1200 parts of sand and gravel aggregate, 10 parts of recycled tire rubber granules, 800 parts of cement, 160 parts of surface-modified steel fiber, 20 parts of microencapsulated composite phase change material, 120 parts of silica fume, 60 parts of fly ash, 10 parts of polycarboxylate superplasticizer, 10 parts of sodium gluconate retarder, and 220 parts of water were mixed and stirred evenly to prepare concrete for wind turbine towers. Among them, the recycled tire rubber granules were processed from waste rubber tires and were black irregular particles with a particle size of about 1.0 mm.

[0057] Example 6

[0058] 60 parts of diatomaceous earth were dried at 60℃ for 16 hours to obtain dried diatomaceous earth; 20 parts of methyl lauryl acid and 15 parts of methyl palmitate were thoroughly mixed, and then 30 parts of dried diatomaceous earth were added. The mixture was impregnated at 30℃ and -0.1MPa vacuum for 24 hours to obtain a composite phase change material; 10 parts of ethyl cellulose were added to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, mixed and stirred at 100℃ for 6 hours, filtered, washed twice with deionized water, and dried under vacuum at 60℃ for 8 hours to obtain modified ethyl cellulose. SiO2-modified ethyl cellulose was prepared by mixing 20 parts of modified ethyl cellulose and 20 parts of nano-silica suspension with a mass concentration of 5%, stirring at 50°C for 3 hours, filtering, washing twice with deionized water, and vacuum drying at 60°C for 8 hours. Two parts of SiO2-modified ethyl cellulose were added to 100 parts of anhydrous ethanol and ultrasonically treated for 10 minutes. Then, 30 parts of composite phase change material were added, mixed and stirred for 30 minutes, filtered, and vacuum dried at 60°C for 8 hours to obtain microcapsule composite phase change material.

[0059] After washing the rice straw with water, it was dried in an oven at 60℃ for 24 hours, and then processed into fine powder using a mixer to obtain rice straw fine powder. Ten parts of rice straw fine powder and 20 parts of cobalt sulfate heptahydrate were added to 100 parts of deionized water, ultrasonicated for 30 minutes, mixed and stirred for 1 hour, dried in an oven at 60℃ for 12 hours, and then pyrolyzed in a muffle furnace at 600℃ for 3 hours to obtain cobalt-modified biochar material. Steel fibers were washed sequentially with acetone and deionized water, and then subjected to a solution with a mass concentration of [missing information - likely a specific concentration]. Pretreated steel fibers were obtained by acid washing with 10% sulfuric acid solution for 3 min and rinsing with deionized water. 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 5 parts KH560 (CAS: 2530-83-8), and 0.5 parts cobalt-modified biochar material were mixed and stirred for 12 min. The pretreated steel fibers were then added and impregnated at 40℃ for 25 min. The mixture was ultrasonically treated and stirred continuously for 30 min. Finally, it was dried at room temperature for 24 h to obtain surface-modified steel fibers.

[0060] 1000 parts of sand and gravel aggregate, 900 parts of cement, 150 parts of surface-modified steel fiber, 10 parts of microcapsule composite phase change material, 140 parts of silica fume, 40 parts of fly ash, 15 parts of polycarboxylate superplasticizer, 5 parts of sodium gluconate retarder, and 160 parts of water are mixed and stirred evenly to prepare concrete for wind turbine towers.

[0061] The present invention also includes comparative examples and related experiments.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that no microcapsule composite phase change material was added, while the other preparation methods and components are completely the same, and the concrete for wind turbine towers is finally obtained.

[0064] Comparative Example 2

[0065] Compared with Example 1, the only difference is that a composite phase change material is directly added to replace the microcapsule composite phase change material, while the other preparation methods and components are completely the same, and the concrete for wind turbine towers is finally obtained.

[0066] Comparative Example 3

[0067] Compared with Example 1, the only difference is that steel fibers are directly added to replace surface-modified steel fibers, while the other preparation methods and components are completely the same, and the concrete for wind turbine towers is finally obtained.

[0068] Performance testing

[0069] Mechanical properties of the concrete for wind turbine towers prepared in Examples 1-6 and Comparative Examples 1-3 were tested. The compressive strength and flexural strength of the samples prepared in Examples 1-6 and Comparative Examples 1-3 were tested in accordance with the national standard GB / T50081-2019 Test Methods for Physical and Mechanical Properties of Concrete to evaluate their mechanical properties. The specific mechanical property test results are shown in Table 1.

[0070] Table 1: Mechanical Performance Test Table

[0071]

[0072] As shown in Table 1, the concrete for wind turbine towers prepared in Examples 1-6 of this invention can all meet the ultra-high strength (C80 grade) requirements of wind turbine towers, and their mechanical properties are significantly better than those of Comparative Examples 2 and 3. Compared to Comparative Example 2, Example 1 significantly improves its overall mechanical properties by using microencapsulated composite phase change materials instead of composite phase change materials; Comparative Example 3 also has a significant impact on mechanical properties due to the lack of surface modification of steel fibers; Example 6 has slightly lower mechanical strength compared to Examples 1-5 because it does not contain recycled tire rubber particles.

[0073] The wind turbine towers prepared in Examples 1-6 and Comparative Examples 1-3 were poured into molds with concrete, vibrated and molded, and cured with moisture. After demolding for 24 hours, the towers were moved to a standard curing room for curing for 90 days to obtain samples. The samples prepared using Examples 1-6 and Comparative Examples 1-3 were subjected to 5 freeze-thaw cycles in accordance with the freeze-thaw resistance test method in the national standard GB / T4111-2013 Test Methods for Concrete Blocks and Bricks. The surface damage of the samples was checked and the compressive strength after freeze-thaw cycles was tested. The compressive strength loss rate (%) was calculated using formula (Ⅰ) to evaluate the freeze-thaw resistance of the samples.

[0074] (I)

[0075] In formula (Ⅰ), , The compressive strength of the sample before freeze-thaw cycles. The compressive strength of the specimens after freeze-thaw cycles is shown in Table 2. The apparent condition of the specimens after freeze-thaw cycles and the specific freeze-thaw resistance test results of the compressive strength loss rate (%) are shown in Table 2.

[0076] Table 2: Freeze-thaw resistance test table

[0077]

[0078] As shown in Table 2, the concrete samples used for wind turbine towers of the present invention performed well after 5 freeze-thaw cycles, with no obvious spalling on the surface. However, Comparative Examples 1 to 3 all showed problems after freeze-thaw cycles, and the compressive strength loss rate increased significantly. Among them, Comparative Example 1 showed a significant decrease in freeze-thaw resistance because it did not contain microcapsule composite phase change material.

[0079] Salt spray corrosion tests were conducted on the concrete samples for wind turbine towers prepared using Examples 1-6 and Comparative Examples 1-3 after curing. The corrosion tests were carried out at room temperature. The salt spray rules were as follows: artificial seawater with a concentration of 20 times was prepared, and salt spray was sprayed onto the concrete surface once every 6 hours, four times a day, for a test period of 90 days. Finally, the degree of surface damage and deterioration of the test samples was observed, and the mass loss rate (%) of the samples was calculated using formula (II) to evaluate the corrosion resistance of the samples. The composition of the artificial seawater with a concentration of 20 times used in the test is shown in Table 3.

[0080] Table 3: Composition of artificial seawater at 20x concentration

[0081]

[0082] (II)

[0083] In formula (II), K m The mass loss rate (%) of the sample. m 0 represents the initial mass of the sample. m Table 1 shows the mass of the sample after a 90-day salt spray corrosion test. The specific corrosion resistance test results of the sample's appearance and mass loss rate (%) after the 90-day salt spray corrosion test are shown in Table 4.

[0084] Table 4: Corrosion Resistance Test Table

[0085]

[0086] As shown in Table 4, the samples prepared by curing the concrete for wind turbine towers according to the present invention still showed good performance after 90 days of salt spray corrosion testing, indicating that the concrete for wind turbine towers prepared by the present invention has good corrosion resistance. Comparative Examples 2 and 3 showed significantly reduced corrosion resistance, and both developed cracks after the salt spray corrosion test. In Comparative Example 3, the lack of modification of the steel fibers caused the steel fibers to rust and expand, leading to internal cracking, overall material spalling, a significantly increased mass loss rate, and a significant decrease in corrosion resistance.

[0087] In summary, the concrete for wind turbine towers prepared by this invention has achieved significant improvements in mechanical properties, freeze-thaw resistance, and corrosion resistance, and can be better applied to wind turbine tower materials to improve the service life of wind turbine towers.

[0088] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing concrete for wind turbine towers, characterized in that, Includes the following steps: S1. By weight, 20-30 parts of methyl laurate and 10-15 parts of methyl palmitate are thoroughly mixed, and then 30 parts of dried diatomaceous earth are added. The mixture is then vacuum impregnated to obtain a composite phase change material. 2-5 parts of SiO2-modified ethyl cellulose are added to anhydrous ethanol and ultrasonically treated. Then, 30-40 parts of the composite phase change material are added, mixed, stirred, filtered, and vacuum dried to obtain a microcapsule composite phase change material. The SiO2-modified ethyl cellulose is composed of 20 parts by weight of modified ethyl cellulose and 20-50 parts by weight of... The modified ethyl cellulose was prepared by mixing a 5% (w / w) nano-silica suspension, stirring at 50°C for 3-5 hours, filtering, washing with deionized water 2-5 times, and vacuum drying at 60-80°C for 8-12 hours; the modified ethyl cellulose was prepared by adding 10 parts of ethyl cellulose to 50 parts of a 30% (w / w) aqueous solution of terminal amino hyperbranched polyamide, mixing and stirring at 100-140°C for 6-10 hours, filtering, washing with deionized water 2-5 times, and vacuum drying at 60-80°C for 8-12 hours. S2. By weight, mix 30 parts zinc phosphate, 200 parts phosphoric acid, 800 parts water, 5-8 parts KH560, and 0.5-3 parts cobalt-modified biochar material, then add pretreated steel fibers for impregnation, ultrasonically treat and continuously stir, and dry to obtain surface-modified steel fibers. Cobalt-modified biochar material is prepared by adding 10-15 parts by weight of rice straw powder and 20-40 parts by weight of cobalt sulfate heptahydrate to 100 parts by weight of deionized water, ultrasonically treating for 30-50 minutes, mixing and stirring for 1-2 hours, drying in an oven at 60℃ for 12-16 hours, and then pyrolyzing in a muffle furnace at 600℃ for 3 hours. Rice straw powder is prepared by washing rice straw with water, drying it in an oven at 60℃ for 24 hours, and then processing it into fine powder using a mixer. Pretreated steel fibers are prepared by washing steel fibers with acetone and deionized water sequentially, acid washing with a 10% sulfuric acid solution at 60℃ for 3-5 minutes, and then rinsing with deionized water. S3. By weight, mix 1000-1200 parts of sand and gravel aggregate, 800-900 parts of cement, 150-200 parts of surface-modified steel fiber, 10-30 parts of microcapsule composite phase change material, 140-200 parts of mineral admixture, 17-25 parts of additives and 150-220 parts of water to prepare concrete for wind turbine towers.

2. The method for preparing concrete for wind turbine towers according to claim 1, characterized in that, The composite phase change material is obtained by thoroughly mixing methyl laurate and methyl palmitate, adding dried diatomaceous earth, and impregnating it under vacuum of -0.1 MPa at 30°C for 24 hours; the dried diatomaceous earth is obtained by drying diatomaceous earth at 60~70°C for 16~24 hours.

3. The method for preparing concrete for wind turbine towers according to claim 1, characterized in that, In step S1, the ultrasonic treatment time is 10-15 minutes, the mixing and stirring time is 30 minutes, and the vacuum drying temperature is 60-80℃ for 8-12 hours.

4. The method for preparing concrete for wind turbine towers according to claim 1, characterized in that, In step S2, the mixing and stirring time is 10-15 minutes, the impregnation temperature is 40℃-65℃ and the time is 20-30 minutes, the ultrasonic treatment and continuous stirring time is 30-50 minutes, and the drying time is 24-36 hours.

5. The method for preparing concrete for wind turbine towers according to claim 1, characterized in that, In step S3, 10-15 parts by weight of recycled tire rubber particles were added and mixed with sand and gravel aggregate, cement, surface-modified steel fiber, microcapsule composite phase change material, mineral admixture, additives and water to prepare concrete for wind turbine towers. The recycled tire rubber granules are made from crushed waste tires.

6. A method for preparing concrete for wind turbine towers according to claim 1, characterized in that, The mineral admixtures are silica fume and fly ash, and the additives are polycarboxylate superplasticizer and sodium gluconate retarder.

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