Recycling method of retired wind power blade

Abstract

According to the recycling method of the retired wind power blade, the material values of different parts of the retired wind power blade are dug in a targeted mode, the main beam part rich in continuous fibers is processed into blocky crude fiber particles in consideration of the difference of the amount of the continuous fibers contained in the main beam part, the web plate part and the skin part of the blade; the web and the skin are processed into fine powder which is synergistically used for preparing the concrete material. According to the method, the blade is subjected to part-by-part differentiation treatment, the material of each part of the blade is endowed with adaptive functional positioning, idle components are avoided, and finally all-component high-value utilization is achieved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and building materials technology, and in particular to a method for recycling retired wind turbine blades. Background Technology

[0002] As the global energy structure shifts towards clean energy, wind power, as a crucial component of renewable energy, has achieved large-scale development. However, this is accompanied by the gradual decommissioning of early-operated wind turbine blades, generating a large amount of wind turbine blade waste. Statistics show that the number of decommissioned wind turbine blades globally is growing rapidly each year, and their harmless treatment and resource utilization have become a key bottleneck restricting the sustainable development of the wind power industry.

[0003] The core material of wind turbine blades is glass fiber reinforced polymer (GFRP), a composite material made of glass fiber and resin matrix. It possesses excellent properties such as lightweight, high strength, and corrosion resistance. However, its complex composition and strong chemical stability also pose significant challenges to waste recycling. Currently, the industry's recycling technologies for retired wind turbine blades mainly include the following categories: 1. Chemical recycling and pyrolysis recycling methods: These methods use chemical reagents to dissolve or pyrolyze the resin matrix at high temperatures, achieving the separation of glass fiber and resin. However, they have two major problems: firstly, the complex process and high equipment investment lead to high recycling costs, making large-scale application difficult; secondly, the use of chemical reagents or high-temperature environments can damage the structure of the glass fiber, reducing its mechanical properties and failing to fully realize its reinforcing potential; 2. Traditional mechanical crushing recycling method: This method uses mechanical crushing to process retired wind turbine blades into granular or powdered fillers, which are then directly incorporated into building materials such as concrete. However, this single recycling model has obvious shortcomings: on the one hand, the crushed mixed particles lack targeted treatment, and when used as fillers, they not only fail to improve the performance of concrete, but also cause the concrete strength to decrease due to problems such as poor interfacial bonding; on the other hand, this method does not distinguish between the reinforcing function of glass fibers in the blades and the potential utilization value of the resin matrix, resulting in a waste of resources.

[0004] In summary, existing technologies for recycling decommissioned wind turbine blades suffer from problems such as limited functionality, low resource utilization, and poor economic benefits. There is an urgent need to develop a new recycling and application technology that can combine material reinforcement and filling functions, adapt to the characteristics of different parts of the blade, and achieve high-value utilization of all components. This would provide a solution for the green treatment of decommissioned wind turbine blades and promote the innovative development of high-performance concrete materials. Summary of the Invention

[0005] To address the problems existing in the background technology, the present invention provides a method for recycling retired wind turbine blades. By accurately matching the material properties of each part of the blade with the functional requirements of concrete, the method achieves high-value utilization of all components of retired wind turbine blades while promoting the innovative development of high-performance concrete materials.

[0006] The specific details of the invention are as follows: This invention provides a method for recycling decommissioned wind turbine blades, the method comprising: The main beam of the blade is mechanically cut and processed into block-shaped coarse fiber particles. The blade's web and skin are mechanically crushed and processed into fine powder. The blocky coarse fiber particles and fine powder are used as filler aggregates in the preparation of concrete materials.

[0007] Optionally, the thickness of the blocky coarse fiber particles is 0.7-1.0 mm, the width is 2.5-4.0 mm, and the length is 50-70 mm.

[0008] Optionally, the particle size of the fine powder is 40-200 mesh.

[0009] Optionally, the step of using the blocky coarse fiber particles and fine powder as filler aggregate for concrete material preparation includes: The blocky coarse fiber particles are premixed with coarse aggregate, and then fine aggregate and fine powder are added. After dry mixing, a mixed aggregate is formed. Add cementitious materials to the mixed aggregates, dry mix, and then add an appropriate amount of water and admixtures to wet mix and obtain the concrete material.

[0010] Optionally, the amount of the blocky coarse fiber particles is 0.8%-1.5% based on the volume fraction of the concrete; and / or The fine powder is added at a rate of 5%-15%.

[0011] Optionally, the concrete material is grade C45-C60, and the amount of blocky coarse fiber particles is 1.2%-1.5% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 31%-40%. The fine powder is added at a rate of 8%-10%, and the total amount of fine aggregate and fine powder is added at a rate of 24%-34%. The amount of the cementitious material is 14%-18%, the amount of water is 5%-7.5%, and the amount of the admixture is less than 1%.

[0012] Optionally, the concrete material is grade C30-C45, and the amount of blocky coarse fiber particles is 1%-1.2% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 32%-38%. The fine powder content is 10%-12%, and the total content of the fine aggregate and the fine powder content is 32%-38%. The amount of the cementitious material is 13%-17%, the amount of water is 5.2%-8.5%, and the amount of the admixture is less than 1%.

[0013] Optionally, the concrete material is grade C15-C25, and the amount of blocky coarse fiber particles is 0.8%-1% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 30%-37%. The fine powder is added at a rate of 12%-15%, and the total amount of fine aggregate and fine powder is 35%-42%. The amount of the cementitious material is 10%-14%, the amount of water is 5%-8.4%, and the amount of the admixture is less than 1%.

[0014] Optionally, the coarse aggregate has a particle size of 5-25 mm, and the fine aggregate has a particle size of 0.16-5 mm.

[0015] Optionally, the concrete material is poured using a high-frequency wall-mounted vibrator.

[0016] This invention provides a method for recycling retired wind turbine blades. The method includes: mechanically cutting the main beam of the blade into block-shaped coarse fiber particles; mechanically crushing the web and skin of the blade into fine powder; and using the coarse fiber particles and fine powder as filler aggregates in conjunction with concrete material preparation.

[0017] Compared with the prior art, the present invention has the following advantages: This invention specifically explores the material value of different parts of retired wind turbine blades. Considering the varying amounts of continuous fibers in the main beam, web, and skin of the blade, the main beam, rich in continuous fibers, is processed into blocky coarse fiber particles, while the web and skin are processed into fine powder, which are then used synergistically in concrete material preparation. By differentiating the treatment of different parts of the blade, this invention assigns appropriate functional roles to the materials of each part, eliminating idle components and ultimately achieving high-value utilization of all components. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of a method for recycling decommissioned wind turbine blades provided in an embodiment of the present invention is shown. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0021] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0022] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Current recycling practices for decommissioned wind turbine blades primarily focus on developing single-function recycling materials. These either process the recycled materials into short fibers for concrete reinforcement, but this is limited by fiber length and dispersion, resulting in limited reinforcement effects and failing to meet the demands of high-performance concrete; or crush them into fine powder for use as filler, but this fails to address the core issues of insufficient tensile strength and poor toughness in concrete. Neither of these technologies achieves synergistic optimization of reinforcement and filler functions. Furthermore, the material composition, fiber content, and structural characteristics of different parts of a wind turbine blade, such as the main beam, web, and skin, vary significantly. Existing recycling solutions do not address these differences individually, instead employing a one-size-fits-all approach. This results in the recycling value of materials from different parts of the blade not being maximized, failing to achieve high-value utilization of all components.

[0025] In view of this, the present invention provides a method for recycling retired wind turbine blades. This invention specifically explores the material value of different parts of retired wind turbine blades. Considering the different amounts of continuous fibers in the main beam, web, and skin of the blade, the main beam, rich in continuous fibers, is processed into blocky coarse fiber particles, while the web and skin are processed into fine powder. These are used synergistically in concrete material preparation. The blocky coarse fiber particles, as a reinforcing phase, can form a spatial support network in the concrete, significantly improving the flexural strength, splitting tensile strength, and toughness of the concrete, solving the problem of limited reinforcement effects of traditional short fibers. The fine powder, as a filler and micro-reinforcing phase, reduces the internal porosity of the concrete through gradation optimization, increasing overall density and thus enhancing compressive stability and resistance to permeation and corrosion (e.g., reducing the chloride ion diffusion coefficient). Furthermore, the resin-based fine powder has good compatibility with cement hydration products, forming a transition layer on the surface of coarse aggregate and coarse fiber, improving interfacial bonding and avoiding interfacial delamination problems encountered when using single fibers or single powders. The recycling method provided by this invention assigns appropriate functional positioning to each part of the blade material, leaving no idle components, and ultimately achieving high-value utilization of all components.

[0026] Figure 1 A flowchart illustrating the method for recycling decommissioned wind turbine blades according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, the method includes: S1. Mechanically cut the main beam of the blade into block-shaped coarse fiber particles; S2. Mechanically crush the web and skin of the blades to process them into fine powder. S3. The blocky coarse fiber particles and fine powder are used as filler aggregates and used synergistically in the preparation of concrete materials.

[0027] In its specific implementation, this invention specifically explores the material value of different parts of retired wind turbine blades. Considering the varying amounts of continuous fibers in the main beam, web, and skin of the blade, the main beam, being the load-bearing core of the blade, utilizes continuous glass fiber reinforced resin (GFRP). This GFRP has a high fiber content (typically over 60%), continuous length, and excellent tensile strength and toughness, making it a natural reinforcing material. The web primarily serves a supporting and separating function, while the skin is responsible for aerodynamic shape and protection. Both have low fiber content (typically below 30%) and dispersed distribution, with a high resin matrix content and poor fiber continuity. Forcing them into fibers would not only result in weak reinforcement but also lead to stress concentration within the concrete due to short and unevenly dispersed fibers. However, both have a dense texture and can be crushed into uniformly sized powder, making them ideal filler materials.

[0028] This invention addresses the differences in glass fiber reinforced resin (GFRP) content across different parts of retired wind turbine blades by employing differentiated treatment for each part. For the main beam, mechanical cutting rather than crushing is chosen, prioritizing the preservation of fiber continuity and structural integrity. The cutting process does not damage the length or interlacing of the fiber bundles, and the resulting blocky coarse fiber particles maintain the mechanical activity of the fibers within the concrete. The web and skin are mechanically crushed into gradient fine powder, designed to meet the particle size distribution requirements of concrete. This particle size range precisely fills the tiny gaps between coarse aggregates and between coarse fiber particles and cement paste, solving the problems of large gaps and insufficient density in traditional concrete coarse aggregates.

[0029] This invention uses coarse fiber particles and fine powder as filler aggregates in synergistic application in concrete material preparation. After uniform dispersion, the coarse fiber particles form a three-dimensional support network within the concrete. On one hand, the high tensile strength of the fibers resists concrete cracking; on the other hand, the interfacial bonding force between the fibers and cement paste transfers the load borne by the concrete to the fibers, significantly improving the flexural and tensile properties of the concrete and compensating for the weakness and brittleness of cement paste. The fine powder, as a filler and micro-reinforcing phase, reduces the porosity of the concrete through gradation optimization, increasing overall density and thus enhancing compressive stability and resistance to penetration and corrosion (e.g., reducing the chloride ion diffusion coefficient). Furthermore, the resin-based fine powder exhibits good compatibility with cement hydration products, forming a transition layer on the surface of the coarse aggregate and coarse fiber, improving interfacial bonding and avoiding interfacial delamination problems encountered when using single fibers or single powders. Coarse fiber particles and fine powder are used together as filler aggregates in concrete materials. By adjusting the dosage, concrete of different strength grades can be obtained to meet the differentiated needs of concrete in high stress areas (C45-C60), general areas (C30-C45), and non-critical areas (C15-C25), thereby improving the resource utilization efficiency, economic benefits, and environmental benefits of retired wind turbine blades.

[0030] In some embodiments, the blocky coarse fiber particles have a thickness of 0.7-1.0 mm, a width of 2.5-4.0 mm, and a length of 50-70 mm.

[0031] In practical implementation, considering that the blocky coarse fiber particles are used as a reinforcing phase in concrete, when cracks appear inside the concrete, the fibers must have sufficient length to bridge the two ends of the crack; that is, to exert a bridging effect. Experimental verification of this invention revealed that if the length of the blocky coarse fiber particles is <50 mm, the fibers cannot be effectively anchored in the cement paste, and are easily pulled out when the crack expands, resulting in a significant reduction in the reinforcing and toughening effects. Conversely, if the blocky coarse fiber particles are too long (>70 mm), they are prone to entanglement and agglomeration during concrete mixing, forming localized fiber clusters, leading to increased porosity and stress concentration inside the concrete, which in turn reduces compressive strength and uniformity. At the same time, a length within 70 mm is suitable for the mixing intensity of conventional concrete mixing equipment (such as a forced mixer), ensuring uniform fiber dispersion.

[0032] Therefore, the present invention has determined through experiments that the preferred length of the blocky coarse fiber particles is 50-70 mm. Blocky coarse fiber particles in this length range can dissolve in concrete to form a continuous three-dimensional support network, which not only ensures the effectiveness of bridging cracks but also avoids agglomeration defects, ultimately achieving improved toughness.

[0033] Furthermore, the thickness of the blocky coarse fiber particles is preferably 0.7-1.0 mm. When the thickness is <0.7 mm, the fiber bundle is easily damaged by the cutting process or broken under load. When the thickness is >1.0 mm, the interfacial bonding area between the fiber and the cement slurry is relatively reduced, the load transfer efficiency decreases, and it is easy to cause insufficient cement slurry coating, forming interfacial cracks.

[0034] Furthermore, the width of the blocky coarse fiber particles is 2.5-4.0 mm. A width that is too narrow (<2.5 mm) will reduce the fiber's moment of inertia and result in insufficient bending resistance; a width that is too wide (>4.0 mm) will disrupt the continuity of the concrete aggregate gradation, creating large gaps between the fiber and the coarse aggregate and fine powder, affecting the density. A width of 2.5-4.0 mm ensures that the fiber possesses sufficient mechanical load-bearing capacity while also maintaining adequate contact with the cement paste, thus improving interfacial bond strength.

[0035] This invention uses multiple orthogonal experiments (variables being length, width, and thickness) to test the effects of different fiber sizes on concrete performance. The results show that when blocky coarse fiber particles meet the combination of length 50-70 mm, width 2.5-4.0 mm, and thickness 0.7-1.0 mm, the resulting concrete exhibits a flexural strength increase of over 30% and a splitting tensile strength increase of over 45%, while maintaining compressive strength without any decrease. Beyond this range (e.g., length 80 mm, thickness 0.5 mm), the fiber agglomeration rate is >15%, the concrete compressive strength decreases by 10%-15%, and the toughness increase is less than 20%.

[0036] In some embodiments, the particle size of the fine powder is 40-200 mesh.

[0037] In practical implementation, since the gaps between coarse aggregates, coarse fiber particles, and cement paste are mostly concentrated in the range of 100-400μm, in order to adapt to the concrete gradation and achieve efficient filling effect, this invention processes the web and skin parts into gradient fine powder with a particle size of 40-200 mesh during mechanical crushing. The fine powder in this particle size range is compatible with the size of cement particles and can form a thin and uniform transition layer on the surface of coarse aggregates and coarse fibers, improve the interfacial bonding state, and avoid interfacial peeling caused by single coarse powder or decreased fluidity of cement paste caused by single fine powder. Furthermore, the upper limit of the fine powder particle size is 40 mesh (≈380 μm). If the particle size is >40 mesh, the particles are too coarse to fit the tiny pores and will disrupt the continuity of aggregate gradation, leading to an increase in the internal porosity and a decrease in density of the concrete. The lower limit of the particle size is 200 mesh (≈75 μm). Fine powder above 200 mesh can fill the capillary pores of the cement paste itself, as well as the micro-voids between coarse powder and cement particles, forming a gradient filling effect where coarse powder fills large pores and fine powder fills micro-voids. If the particle size is <200 mesh, the powder is too fine and easily agglomerates, forming secondary voids and negating the filling effect. Experiments show that the agglomeration rate of fine powder above 250 mesh is >20%, and the impermeability of concrete decreases by 15%. On the other hand, the gradient particle size of 40-200 mesh can cover voids of different scales inside the concrete, reducing the porosity by more than 25%, and significantly improving the density, impermeability, and corrosion resistance.

[0038] In some embodiments, using the coarse fiber particles and fine powder as filler aggregates for concrete material preparation includes: The coarse fiber particles are premixed with coarse aggregate, and then fine aggregate and fine powder are added and dry-mixed to form mixed aggregate. Add cementitious materials to the mixed aggregates, dry mix, and then add an appropriate amount of water and admixtures to wet mix and obtain the concrete material.

[0039] In practice, different parts of the retired wind turbine blades are treated differently. The resulting coarse fiber particles and fine powder are used together in the preparation of concrete. Through the step-by-step feeding and dry mixing design, the problems of coarse fiber agglomeration, uneven dispersion of fine powder and weak interfacial bonding of components are precisely solved.

[0040] Specifically, the first step in the preparation process is to premix coarse fiber particles with coarse aggregate. Due to the rough surface and large mass of the coarse aggregate (5-31.5 mm in diameter), the friction and impact forces generated during mechanical mixing with the coarse fiber particles (50-70 mm in length) allow the coarse aggregate to act as a physical dispersion carrier. The coarse fibers are spread apart by the aggregate particles and uniformly adsorbed onto their surface, preventing fiber agglomeration caused by high inter-fiber friction when the coarse fibers are mixed alone. This effectively reduces the coarse fiber agglomeration rate, laying the foundation for the subsequent formation of a three-dimensional reinforcement network in the concrete and preventing weak areas and stress concentrations within the concrete due to agglomeration.

[0041] Specifically, the second step in the preparation process involves adding fine aggregate and fine powder to the pre-mixed coarse fiber particles and coarse aggregate, followed by further dry mixing to form a gradient-filled and dry-uniformed mixed aggregate, thus optimizing the particle size distribution and achieving a gradient filling from large voids to small voids. Under dry mixing conditions, fine aggregate (0.15-4.75 mm) fills the macroscopic voids between coarse aggregate and coarse fibers, while fine powder further fills the microscopic voids between fine aggregate and coarse aggregate, forming a gradient gradation of coarse aggregate → fine aggregate → fine powder. Furthermore, dry mixing eliminates moisture interference, preventing the fine powder from agglomerating due to water contact and allowing it to be evenly distributed within the aggregate gaps. The resulting mixed aggregate has a more continuous particle size distribution, laying a structural foundation for improving the density of subsequent concrete. Simultaneously, the fine powder comes into contact with the aggregate in advance, preventing it from being encapsulated by cement paste during subsequent wet mixing and thus failing to perform its filling function.

[0042] Specifically, the third step in the preparation process is to add cementitious materials to the mixed aggregates. The cementitious materials (such as cement of different grades with particle sizes of 1-100 μm) are uniformly attached to the surface of the mixed aggregates (coarse aggregates, coarse fibers, fine aggregates and fine powders) under dry mixing conditions through the mechanical force of stirring, forming a layer of dry cement. In this process, the cementitious materials can fully fill the tiny gaps between the fine powders and aggregates, and at the same time form preliminary physical adsorption with the surface of coarse fibers, which facilitates the interfacial bonding after the subsequent hydration reaction.

[0043] Specifically, the fourth step in the preparation process is to further add water and admixtures to the mixture for wet mixing. The addition of water can trigger the hydration reaction of the cementitious materials to generate cement stone. The admixtures reduce the water-cement ratio through surface activity, improve the fluidity of the cement paste, and ensure that the cement paste can fully coat all the mixed aggregate components, especially the surface of coarse fibers and the gaps between fine powders. The mechanical stirring in the wet mixing stage further integrates the components. The coarse fibers fix their three-dimensional distribution in the cement paste, and the fine powders are tightly combined with the hydration products, resulting in concrete with good workability and a uniform and dense internal structure. The reinforcing effect of coarse fibers and the filling effect of fine powders work together to effectively improve flexural strength and toughness, while maintaining stable compressive strength.

[0044] In some embodiments, the amount of the blocky coarse fiber particles is 0.8%-1.5% by volume fraction of the concrete; and / or The fine powder is added at a rate of 5%-15%.

[0045] In practical implementation, the blocky coarse fiber particles need to form a continuous three-dimensional support network in the concrete to effectively bridge cracks and transfer loads. Experimental studies have shown that if the dosage of blocky coarse fiber particles is less than 0.8%, the fiber distribution density is insufficient, the network is discontinuous and broken, and cracks cannot be effectively anchored during propagation. This results in limited improvement in flexural strength and toughness, failing to compensate for the tensile weakness of cement paste. When the dosage reaches 0.8%, the fiber network is initially formed, the splitting tensile strength of the concrete is improved, meeting the mechanical requirements of general areas, representing the minimum threshold for effective reinforcement. Further increasing the coarse fiber dosage to >1.5%, even after pre-mixing and dispersing with coarse aggregate, will still lead to increased agglomeration due to increased friction between fibers, forming internal stress concentration points. Simultaneously, excessive fibers will crowd out the aggregate gaps, reducing concrete workability and making compaction difficult during vibration, ultimately lowering compressive strength. Therefore, this invention recommends a preferred dosage of blocky coarse fiber particles of 0.8%-1.5%.

[0046] In practical implementation, the core function of fine powder is to fill the gradient voids between coarse aggregate, coarse fiber, and fine aggregate. Experiments have shown that if the fine powder content is less than 5%, the filling amount is insufficient, leading to excessively high concrete porosity, limited improvement in density, and insignificant improvement in impermeability and corrosion resistance, failing to realize the value of micro-filling and interface strengthening. When the content reaches 5%, the fine powder can initially fill the gaps between coarse aggregate, and the durability of concrete begins to improve significantly. The proportion of fine powder replacing fine aggregate should not be too high. If the content is greater than 15%, it will lead to insufficient proportion of concrete skeleton components (aggregates), weakening the overall load-bearing capacity. At the same time, excessive fine powder will increase the specific surface area, requiring more cement paste to coat it, which can easily lead to increased concrete viscosity, decreased fluidity, and bleeding or segregation. Therefore, this invention recommends a fine powder content of 5%-15%.

[0047] In some implementations, based on high-stress load-bearing scenarios (such as offshore wind turbine pile caps, core beams and columns of buildings, etc.), which need to withstand impact loads, bending stresses, and complex stress concentrations, the preferred dosage of blocky coarse fiber particles in concrete is 1.2%-1.5%, and the preferred dosage of fine powder is 8%-10%, with a water-cement ratio of 0.35-0.42. Among them, the 1.2%-1.5% coarse fiber can provide dual protection of active crack resistance and passive load-bearing capacity, making up for the brittleness of conventional concrete under dynamic loads and solving the core mechanical shortcomings under high stress. The 8%-10% fine powder only fills the macroscopic voids between coarse fibers and coarse / fine aggregates, as well as the microscopic voids on the fiber surface. It will not compete with coarse fibers for cement paste coating due to excessive fine powder, ensuring that a sufficiently thick hydration product transition layer can be formed on the fiber surface, avoiding weak interfacial bonding. A water-cement ratio of less than 0.42 can ensure high strength and low porosity, making it suitable for complex application environments such as marine and freeze-thaw environments.

[0048] As a specific example, the concrete material prepared in this embodiment for use in high-stress load-bearing scenarios meets the C45-C60 grade requirements. During preparation, based on the volume fraction of the concrete, the content of the blocky coarse fiber particles is 1.2%-1.5%, and the total content of the coarse aggregate and the blocky coarse fiber particles is 31%-40%; the content of the fine powder is 8%-10%, and the total content of the fine aggregate and the fine powder is 24%-34%; the content of the cementitious material is 14%-18%, the content of the water is 5%-7.5%, and the content of the admixture is less than 1%.

[0049] In some implementations, for the application of concrete materials in general scenarios, such as beams and columns of civil buildings, conventional wind power foundations, and non-core components of bridges, in order to meet the requirements of universality and balance, the preferred dosage of blocky coarse fiber particles in concrete is 1%-1.2%, the preferred dosage of fine powder is 10%-12%, and the water-cement ratio is 0.4-0.5. Among them, with a dosage of 1%-1.2% blocky coarse fiber particles, the fibers can form a dense and non-crowded three-dimensional support network, which not only meets the core requirements of tensile strength, crack resistance, and toughness in general scenarios, but also avoids redundant performance with high dosage, thus avoiding material waste. The dosage of 10%-12% fine powder can achieve full-scale void filling between coarse aggregate, coarse fiber, fine aggregate, and fine powder, which not only ensures that the compressive strength is comparable to that of the reference concrete, but also improves the impermeability and corrosion resistance through the compaction effect, making it suitable for complex environments such as humid and mildly corrosive environments.

[0050] As a specific example, the general-purpose concrete material prepared in this embodiment meets the C30-C45 grade requirements. During preparation, based on the volume fraction of the concrete, the content of the blocky coarse fiber particles is 1%-1.2%, and the total content of the coarse aggregate and the blocky coarse fiber particles is 32%-38%; the content of the fine powder is 10%-12%, and the total content of the fine aggregate and the fine powder is 32%-38%; the content of the cementitious material is 13%-17%; the content of the water is 5.2%-8.5%; and the content of the admixture is less than 1%.

[0051] In some implementations, for applications of concrete materials in non-critical / low-stress scenarios, such as secondary building components, roadbed concrete, and non-load-bearing walls, since there is no requirement for high-strength tensile / crack resistance, the content of blocky coarse fiber particles in the concrete can be relatively low, preferably 0.8%-1%, while the content of fine powder can be relatively high, preferably 12%-15%. The combination of high fine powder content (12%-15%) with low coarse fiber content (0.8%-1.0%) compensates for the density deficiency caused by insufficient fiber content through the filling effect, ensuring that the compressive strength does not decrease; the water-cement ratio is 0.5-0.6. Among them, 0.8%-1% of blocky coarse fiber particles can form a sparse but continuous three-dimensional fiber network, meeting the basic crack resistance requirements (such as avoiding shrinkage cracks); while a high dosage of 2%-15% of fine powder can maximize gradient filling, filling both the macroscopic voids of coarse aggregate and coarse fiber, and the microscopic voids of fine aggregate and cement particles, maximizing the reduction of concrete porosity and significantly improving density. Furthermore, the high dosage of fine powder can maximize the consumption of retired blade web and skin materials, enabling blade material utilization to exceed 95%; simultaneously, the fine powder replaces 12%-15% of fine aggregate, reducing the amount of natural sand used, effectively lowering concrete material costs, and meeting the core economic requirements of non-critical scenarios.

[0052] As a specific example, the concrete material provided by this invention for use in non-critical / low-stress scenarios meets the grade requirements of C15-C25. During preparation, based on the volume fraction of the concrete, the content of the blocky coarse fiber particles is 0.8%-1%, and the total content of the coarse aggregate and the blocky coarse fiber particles is 30%-37%; the content of the fine powder is 12%-15%, and the total content of the fine aggregate and the fine powder is 35%-42%; the content of the cementitious material is 10%-14%, the content of the water is 5%-8.4%, and the content of the admixture is less than 1%.

[0053] In some embodiments, the coarse aggregate has a particle size of 5-25 mm, and the fine aggregate has a particle size of 0.16-5 mm.

[0054] In some embodiments, the concrete material is poured using a high-frequency wall-mounted vibrator.

[0055] To enable those skilled in the art to more clearly understand the present invention, the following embodiments will be used to describe in detail a method for recycling decommissioned wind turbine blades according to the present invention.

[0056] Example 1 (1) Raw material preparation 1) Recycling and processing of decommissioned wind turbine blades Main beam section: Select glass fiber reinforced composite (GFRP) wind turbine blades that have been retired after 15 years of service. Separate the main beam (fiber content 65%) and process it into block coarse fiber particles through precision mechanical cutting. The size is controlled to be 60 mm (length) × 3.0 mm (width) × 0.9 mm (thickness). The fiber purity is ≥98%, with no obvious breakage or clumping.

[0057] Web / skin section: Separate the web and skin (fiber content 28%), crush them with a jaw crusher and then sieve them to prepare 40-200 mesh gradient fine powder, of which 80-120 mesh particles account for 60%, with uniform particle size distribution and moisture content ≤0.5%.

[0058] Core material processing: The PVC core material is separated and recycled separately, achieving an overall resource utilization rate of 95.6% for the blades.

[0059] 2) Conventional concrete raw materials Coarse aggregate: 5-25 mm continuously graded basalt crushed stone, mud content ≤1.0%, crushing value ≤12%.

[0060] Fine aggregate: natural river sand, fineness modulus 2.6, mud content ≤2.0%, mud lump content ≤0.5%.

[0061] Cementitious material: P O 42.5 ordinary Portland cement, specific surface area 350 m² 2 / kg; Grade II fly ash, water requirement ≤95%, cement to fly ash mass ratio is 7:3.

[0062] Admixture: Polycarboxylate superplasticizer, water reduction rate ≥30%, solid content 20%.

[0063] Mixing water: tap water, which meets the requirements of the "Standard for Water Used in Concrete" GB / T 14684-2011.

[0064] (2) Concrete preparation process (total mixing volume 1 m³) 3 ) 1) Mix design Reference concrete mix proportion (kg / m³) 3 ): 450 kg of cementitious materials (315 kg of cement and 135 kg of fly ash), 1180 kg of coarse aggregate, 650 kg of fine aggregate, 180 kg of water, 6.75 kg of admixture, and a water-cement ratio of 0.40.

[0065] The proportions of this embodiment are as follows: 1170 kg of coarse aggregate, 1.1% (30.2 kg) of blocky coarse fiber particles by volume, and a total content of 35% of coarse aggregate and coarse fiber; 520 kg of fine aggregate, 302 kg of fine powder (11% by volume), and a total content of 35% of fine aggregate and fine powder; the remaining components are the same as the reference group.

[0066] 2) Graded feeding and mixing process Premixing stage: 1170 kg of coarse aggregate and 30.2 kg of coarse fiber particles are put into a forced mixer, the speed is set to 30 r / min, and premixed for 30 seconds until the coarse fiber is uniformly adsorbed on the surface of the coarse aggregate without obvious agglomeration.

[0067] Dry mixing stage: Add 520 kg of fine aggregate and 302 kg of fine powder, maintain a rotation speed of 30 r / min, and dry mix for 60 seconds to form a uniform aggregate mixture (continuous particle size distribution, no fine powder agglomeration).

[0068] Dry mixing of cementitious materials: Add 450 kg of cementitious materials (cement + fly ash), increase the rotation speed to 35 r / min, and dry mix for 30 seconds to make the cementitious materials evenly coat the surface of the aggregates and form a dry mixing system.

[0069] Wet mixing stage: Mix 180 kg of water and 6.75 kg of admixture evenly in advance, slowly add to the mixer, and wet mix for 120 seconds at a speed of 35 r / min until the concrete mixture is uniform in color, without segregation or bleeding.

[0070] 3) Pouring and Vibration Process Mold preparation: Use 100mm×100mm×400mm prism molds (for bending and tensile tests), 150mm×150mm×150mm cube molds (for compressive tests), and Φ100mm×200mm cylinder molds (for durability tests). Apply release agent to the inner wall of the molds.

[0071] Pouring: The concrete mixture is poured into the test mold in two layers, with each layer being about 1 / 2 the height of the test mold. Aggregate accumulation should be avoided during the pouring process.

[0072] Vibration: A high-frequency wall-mounted vibrator (vibration frequency 120Hz, amplitude 0.8mm) was used and fixed to the outside of the test mold. The vibration time was extended by 40% compared with the conventional method (60 seconds per layer, total vibration time 120 seconds) until the concrete surface showed slurry and no obvious air bubbles overflowed.

[0073] Smoothing and curing: After vibration, smooth the surface of the test mold in time and place it in a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for 28 days.

[0074] 4) Comparison group settings A baseline control group (C40 conventional concrete, without coarse fibers and fine powder) was set up according to the baseline concrete mix proportion. Except for the absence of recycled materials, the mix proportion, mixing process, and curing conditions were completely consistent with those in this embodiment. Three parallel test blocks were prepared for each test item, and the average value was taken as the test result.

[0075] (3) Implementation process for effect verification 1) Test Content Slump test: Before pouring, take concrete mix and fill it into a slump cone in layers according to the standard method. After compaction, lift the cone and measure the slump height of the mix. At the same time, observe the cohesiveness and water retention.

[0076] Fiber dispersion test: After 28 days of curing, three cubic test blocks were randomly selected, crushed, and soaked in 5% NaOH solution for 72 hours (to dissolve the cementitious material). The fibers were filtered out, washed, dried, and weighed. The ratio of the actual fiber content to the designed dosage was calculated.

[0077] Mechanical property testing: Take out the test block after 28 days of curing, wipe off the surface moisture, place it on the testing machine, and load it according to the standard loading rate (compressive 0.5-0.8 MPa / s, tensile 0.05-0.08 MPa / s, bending 0.02-0.05 MPa / s), record the failure load, and calculate the corresponding strength.

[0078] Chloride ion diffusion coefficient test: The cylindrical specimen is cut into 50 mm thick slices, vacuum-saturated with water and placed in the test tank. A 60 V DC voltage is applied for 24 hours, the amount of electricity passing through the concrete is measured, and the chloride ion diffusion coefficient is calculated.

[0079] Permeability test: Place the test block on the permeability tester, starting from 0.1 MPa, increase the pressure by 0.1 MPa every 8 hours, and observe whether water seeps into the bottom surface of the test block until 2 out of 3 test blocks seep into the water. Record the pressure of the previous level as the permeability grade.

[0080] 2) Test Results Table 1 Test Results

[0081] Referring to the test results shown in Table 1, the concrete slump in this embodiment reached 185 mm, with good cohesiveness and water retention, and no segregation or bleeding; the fiber dispersion rate was 97.5%, proving that the graded feeding process and high-frequency vibrator effectively solved the problem of coarse fiber agglomeration and are compatible with conventional construction equipment.

[0082] In this embodiment, the concrete exhibits a slight increase in compressive strength, while its tensile, flexural, and toughness are all improved by more than 40%, achieving both reinforcement and toughening effects. This verifies the synergistic effect of the coarse fiber three-dimensional reinforcement network and the gradient filling of fine powder.

[0083] In this embodiment, the chloride ion diffusion coefficient of the concrete was reduced by 41.2%, and the impermeability grade reached P10. This indicates that the filling effect of the fine powder effectively reduced the internal pores of the concrete, blocked the penetration channels of harmful substances, and made it suitable for humid and mildly corrosive environments.

[0084] In this embodiment, the utilization rate of decommissioned blade materials in concrete reaches 95.6%, and fine powder replaces 11% of fine aggregate. The concrete material meets the requirements for use in general areas, and the cost of concrete material is reduced by 16.2%. This not only solves the problem of wind turbine blade waste disposal, but also reduces the cost of building materials, which is in line with the concept of circular economy.

[0085] Example 2 (1) Raw material preparation 1) Recycling and processing of decommissioned wind turbine blades Main beam section: GFRP blades of offshore wind turbines that have been retired after 12 years of service (fiber retention rate ≥90% after salt spray aging) are selected. The main beam structure (fiber content 68%) is separated and processed into block-shaped coarse fiber particles using CNC precision cutting equipment. The size is strictly controlled to 60 mm (length) × 3.5 mm (width) × 0.8 mm (thickness). The fiber bundle integrity is ≥95%, with no burrs or resin peeling. After soaking in salt water for 72 hours, there is no obvious corrosion, ensuring stability in the marine environment.

[0086] Web / Skin Section: The web and skin structure of the separated blades (fiber content 30%) are coarsely crushed by a jaw crusher and finely crushed by an impact crusher. After being graded and screened by a double-layer vibrating screen, fine powder with a gradient of 80-120 mesh is prepared, of which particles of about 100 mesh account for 70%. The particle size distribution is uniform, the moisture content is ≤0.3%, the resin content is ≥25%, and the chloride ion content is ≤0.02%, which meets the standard for admixtures for marine concrete.

[0087] Core material processing: The PVC core material is separated and recycled separately, achieving an overall resource utilization rate of 95.8% for the blades.

[0088] 2) Conventional concrete raw materials Coarse aggregate: 5-31.5 mm continuously graded granite crushed stone, mud content ≤0.5%, crushing value ≤10%, needle-like and flaky particle content ≤8%, mass loss rate ≤3% after freeze-thaw resistance test (50 cycles), suitable for marine freeze-thaw environment.

[0089] Fine aggregate: desalinated sea sand, fineness modulus 2.8, mud content ≤1.0%, mud lump content ≤0.3%, chloride ion content ≤0.03%, meeting the requirements for fine aggregate in marine concrete.

[0090] Cementitious material: P II 42.5R sulfate-resistant cement (sulfate resistance grade KS150), specific surface area 360m² 2 / kg; Grade I silica fume (SiO2 content ≥95%), S95 grade slag powder, cementitious material ratio is cement: silica fume: slag powder = 6:1:3, total usage 480 kg / m³ 3 .

[0091] Admixture: Polycarboxylate-based high-efficiency water-reducing agent for marine engineering, with a water reduction rate of ≥35%, solid content of 25%, and chloride ion content of ≤0.01%, possessing anti-salt pollution, retarding and plastic-preserving functions.

[0092] Mixing water: Desalinated seawater that meets standards, with a chloride ion content ≤200 mg / L and a pH value of 7.5-8.5.

[0093] (2) Concrete preparation process (total mixing volume 1m³) 3 ) 1) Mix design Standard C45 marine concrete mix proportion (kg / m³) 3 ): 520 kg of cementitious material, 1150 kg of coarse aggregate, 620 kg of fine aggregate, 208 kg of desalinated seawater, 7.8 kg of admixture, and a water-cement ratio of 0.40.

[0094] The proportions in this embodiment are as follows: 1130 kg of coarse aggregate, 1.3% (36.5 kg) of coarse fiber particles by volume, and 38% of the total coarse aggregate and coarse fiber by volume. 460 kg of fine aggregate, 252 kg of fine powder (9% by volume), and the total content of fine aggregate and fine powder is 29%. The remaining components (cementing materials, water, and additives) are consistent with the baseline group to ensure that the core performance in marine engineering scenarios is not degraded.

[0095] 2) Graded feeding and mixing process Premixing stage (30s): 1130 kg of coarse aggregate and 36.5 kg of coarse fiber particles are put into the mixer and the speed is set to 35 r / min. Through the impact and friction of the coarse aggregate, the coarse fiber is evenly adsorbed on the surface of the coarse aggregate, breaking the fiber entanglement and achieving preliminary dispersion.

[0096] Dry mixing stage (60s): Add 460 kg of desalinated sea sand and 252 kg of fine powder from the web, and maintain a rotation speed of 35 r / min. During the dry mixing process, the fine powder fills the macroscopic gaps between the coarse aggregate and coarse fiber, forming a continuous graded mixed aggregate without fine powder agglomeration.

[0097] Dry mixing of cementitious materials (30 seconds): Add 520 kg of cementitious materials (cement + silica fume + slag powder), increase the speed to 40 r / min, and dry mix to make the cementitious materials evenly coat the surface of the mixed aggregates, forming a dense dry coating layer, and avoid the cementitious materials from clumping when wet mixing.

[0098] Wet mixing stage (120 seconds): Mix 208 kg of desalinated seawater and 7.8 kg of marine engineering admixture evenly in advance, and add it to the mixer in two batches (70% first, and the remaining 30% after 30 seconds). Maintain a speed of 40 r / min for wet mixing until the concrete mixture has a uniform color, good cohesion, and no segregation or bleeding. The total mixing time is 240 seconds.

[0099] 3) Pouring and Vibration Process Mold preparation: Steel templates (12 mm thick, with rigidity to meet lateral pressure requirements) are used. The inner wall is coated with marine engineering release agent. The template size is 3 m × 2 m × 1.5 m (single-section casting size of pile cap), and vibration observation holes are reserved.

[0100] Casting process: Pumping is used, and the casting speed is controlled at 0.3 m. 3 The mixture is poured in 3 layers (500mm thick each) at a rate of 10 ...

[0101] Vibration process: A high-frequency wall-mounted vibrator (vibration frequency 130 Hz, amplitude 0.9 mm, power 5.5 kW) is used, arranged at 500 mm intervals along the outer side of the template. The conventional vibration time is 60 seconds per layer. In this embodiment, it is extended by 40% to 84 seconds per layer, with a total vibration time of 252 seconds. Vibration is carried out until the concrete surface is uniformly covered with slurry and no obvious air bubbles overflow. The density of the deeper layers is confirmed through observation holes.

[0102] Finishing and curing: A second finishing process is carried out within 3 hours after pouring to prevent surface shrinkage cracks; triple curing is adopted with "plastic film + geotextile + curing agent", the curing temperature is controlled at 15-25 ℃, the relative humidity is ≥90%, the standard curing is 28 days, and then seawater spray curing is adopted for 60 days to simulate the marine service environment.

[0103] 4) Comparison group settings A benchmark control group (C45 conventional marine concrete, without coarse fibers and fine powder) was set up according to the C45 marine concrete mix proportion. The mix proportion, mixing process, pouring vibration and curing conditions were completely consistent with those in this embodiment. Six parallel test blocks were prepared for each test item (higher number of parallel samples are required for marine engineering scenarios), and the average value was taken as the final result.

[0104] (3) Implementation process for effect verification 1) Test Content The same test items as in Example 1 will not be repeated here. In this example, a sulfate resistance test was also conducted: the test block was immersed in a 5% Na2SO4 solution, and the mass loss rate and strength change rate were tested every 30 days for 180 days to evaluate the durability in the marine sulfate environment.

[0105] 2) Test Results Table 2 Test Results

[0106] Referring to the test results shown in Table 2, the concrete in this embodiment has a slump of 188 mm, a spread of 525 mm, excellent cohesiveness and water retention, no segregation or bleeding, and a fiber dispersion rate of 97.8%, which fully meets the pumping and pouring requirements of offshore wind power pier caps. This proves that the graded feeding process and high-frequency vibrator effectively solve the problem of coarse fiber dispersion in marine concrete.

[0107] In this embodiment, the concrete compressive strength is basically equivalent to that of the benchmark group (47.5 MPa ≥ C45 design requirement after 28 days), the splitting tensile strength is increased by 50.0%, and the flexural strength is increased by 87.5%. This significantly improves the shortcomings of conventional marine concrete, which is weak in tensile strength and prone to brittle fracture. It can effectively resist wave impact and stress concentration in the pile cap area and reduce the risk of cracking.

[0108] In this embodiment, the chloride ion diffusion coefficient of concrete was reduced by 42.4%, and the mass loss rate against sulfate attack was reduced by 53.3%. This indicates that the gradient filling effect of fine powder effectively blocked the penetration channels of harmful substances such as chloride ions and sulfates in the marine environment, and extended the service life of the pile cap structure (expected to reach more than 50 years, meeting the design life of offshore wind power).

[0109] In this embodiment, the utilization rate of decommissioned wind turbine blade materials in concrete reaches 95.8%, and fine powder replaces 10% of sea sand, reducing the mining of natural aggregates. The physical recycling process avoids chemical pollution and the environmental pressure caused by the incineration or landfill of decommissioned wind turbine blades. At the same time, the performance of concrete materials meets the requirements for use in high-stress areas, and the cost of concrete materials is reduced by 15.8%, achieving a win-win situation of resource recycling and engineering benefits.

[0110] Example 3 (1) Raw material preparation 1) Recycling and processing of decommissioned wind turbine blades Main beam section: Select GFRP wind turbine blades that have been retired after 10 years of service, separate the main beam (fiber content 62%), and process it into block coarse fiber particles by mechanical cutting. The size is controlled to be 55 mm (length) × 3.0 mm (width) × 0.8 mm (thickness), with fiber purity ≥ 96% and no obvious agglomeration.

[0111] Web / skin section: Separate the web and skin (fiber content 26%), crush them with a crusher and then sieve them to prepare 40-200 mesh gradient fine powder, of which 80-120 mesh particles account for 55%, with uniform particle size distribution and moisture content ≤0.6%.

[0112] Core material processing: The PVC core material is separated and recycled separately, achieving an overall resource utilization rate of 95.5% for the blades.

[0113] 2) Conventional concrete raw materials Coarse aggregate: 5-31.5 mm continuously graded limestone crushed stone, with mud content ≤1.5%, crushing value ≤16%, and needle-like and flaky particle content ≤15%.

[0114] Fine aggregate: ordinary river sand, fineness modulus 2.3, mud content ≤3.0%, mud lump content ≤1.0%.

[0115] Cementitious material: P O 32.5 ordinary Portland cement, specific surface area 330 m² 2 / kg; Grade III fly ash (optional), cement to fly ash mass ratio of 8:2, total usage 320 kg, volume fraction 12%.

[0116] Admixture: Polycarboxylate superplasticizer, water reduction rate ≥25%, solid content 18%, volume fraction <1%.

[0117] Mixing water: tap water, volume fraction 7.2%.

[0118] (2) Concrete preparation process (total mixing volume 1m³) 3 ) 1) Mix design Standard C20 concrete mix proportion (kg / m³) 3 ): 320 kg of cementitious materials (256 kg of cement and 64 kg of fly ash), 1100 kg of coarse aggregate, 680 kg of fine aggregate, 230 kg of water, 4.8 kg of admixture, and a water-cement ratio of 0.50.

[0119] The proportions in this embodiment are as follows: 1080 kg of coarse aggregate, 0.9% (24.8 kg) of blocky coarse fiber particles by volume, and 34% of the total coarse aggregate and coarse fiber by volume. Fine aggregate 450 kg, fine powder volume fraction 13% (mass 358 kg), total fine aggregate and fine powder content (volume fraction) 39%; The remaining components are consistent with the reference group.

[0120] 2) Graded feeding and mixing process Premixing stage: 1080 kg of coarse aggregate and 24.8 kg of coarse fiber particles are put into a forced mixer, the speed is set to 28 r / min, and premixed for 30 seconds until the coarse fiber is uniformly adsorbed on the surface of the coarse aggregate without obvious agglomeration.

[0121] Dry mixing stage: Add 450 kg of fine aggregate and 358 kg of fine powder, maintain a rotation speed of 28 r / min, and dry mix for 60 seconds to form a uniform aggregate mixture without fine powder clumping.

[0122] Dry mixing of cementitious materials: Add 320 kg of cementitious materials (cement + fly ash), increase the rotation speed to 32 r / min, and dry mix for 30 seconds to make the cementitious materials evenly coat the surface of the aggregate.

[0123] Wet mixing stage: Mix 230 kg of water and 4.8 kg of admixture evenly in advance, slowly add to the mixer, and wet mix for 120 seconds at a speed of 32 r / min until the concrete mixture is uniform in color, without segregation or bleeding.

[0124] 3) Pouring and Vibration Process Mold preparation: Use 150 mm × 150 mm × 150 mm cube molds (for compressive strength testing) and 100 mm × 100 mm × 400 mm prism molds (for tensile strength testing). Apply release agent to the inner wall of the molds.

[0125] Pouring: The concrete mixture is poured into the test mold in two layers, with each layer being about 1 / 2 the height of the test mold. Aggregate accumulation should be avoided during the pouring process.

[0126] Vibration: Use an immersion vibrator (vibration frequency 90 Hz) and vibrate for 40 seconds per layer until the concrete surface is covered with slurry and no obvious air bubbles overflow.

[0127] Finishing and curing: After vibration, smooth the surface in time and place it in a curing room with a temperature of 20±3 ℃ and a relative humidity of ≥90% for 28 days.

[0128] 4) Comparison group settings A benchmark control group (without coarse fibers and fine powder) was set up according to the benchmark C20 concrete mix proportion. The mix proportion, mixing process, and curing conditions were completely consistent with those in this embodiment. Three parallel test blocks were prepared for each test item, and the average value was taken as the test result.

[0129] (3) Implementation process for effect verification 1) Test Content Slump test, fiber dispersion test, compressive strength test, splitting tensile strength test, and impermeability grade test. 2) Test Results Table 3 Test Results

[0130] Referring to the test results shown in Table 3, the concrete material obtained in this embodiment meets the usage requirements of C20 low-stress scenarios, and the workability of the concrete is suitable for the construction of infill walls; the coarse fiber content of 0.9% meets the foundation crack resistance requirements, the splitting tensile strength is increased by 27.8%, and shrinkage cracks are effectively reduced; the high content of fine powder of 13% fully fills the voids, the compressive strength is increased by 6.0%, and the impermeability grade reaches P8; the utilization rate of retired blade materials reaches 95.5%, maximizing the consumption of recycled materials, and the cost of concrete materials is reduced by 18.5%, which is suitable for the economic and environmental protection requirements of non-critical scenarios.

[0131] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0132] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0133] The above provides a detailed description of a method for recycling retired wind turbine blades provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for recycling decommissioned wind turbine blades, characterized in that, The method includes: The main beam of the blade is mechanically cut and processed into block-shaped coarse fiber particles. The blade's web and skin are mechanically crushed and processed into fine powder. The blocky coarse fiber particles and fine powder are used as filler aggregates in the preparation of concrete materials.

2. The method for recycling decommissioned wind turbine blades according to claim 1, characterized in that, The blocky coarse fiber particles have a thickness of 0.7-1.0 mm, a width of 2.5-4.0 mm, and a length of 50-70 mm.

3. The method for recycling decommissioned wind turbine blades according to claim 1, characterized in that, The particle size of the fine powder is 40-200 mesh.

4. The method for recycling decommissioned wind turbine blades according to claim 1, characterized in that, The step of using the blocky coarse fiber particles and fine powder as filler aggregates for concrete material preparation includes: The blocky coarse fiber particles are premixed with coarse aggregate, and then fine aggregate and fine powder are added. After dry mixing, a mixed aggregate is formed. Add cementitious materials to the mixed aggregates, dry mix, and then add an appropriate amount of water and admixtures to wet mix and obtain the concrete material.

5. The method for recycling decommissioned wind turbine blades according to claim 1 or 4, characterized in that, The concrete material is grade C15-C60, and the amount of the blocky coarse fiber particles is 0.8%-1.5% by volume; and / or The fine powder is added at a rate of 5%-15%.

6. The method for recycling decommissioned wind turbine blades according to claim 4, characterized in that, The concrete material is grade C45-C60, and the amount of blocky coarse fiber particles is 1.2%-1.5% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 31%-40%. The fine powder is added at a rate of 8%-10%, and the total amount of fine aggregate and fine powder is added at a rate of 24%-34%. The amount of the cementitious material is 14%-18%, the amount of water is 5%-7.5%, and the amount of the admixture is less than 1%.

7. The method for recycling decommissioned wind turbine blades according to claim 4, characterized in that, The concrete material is grade C30-C45, and the amount of blocky coarse fiber particles is 1%-1.2% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 32%-38%. The fine powder is added at a rate of 10%-12%, and the total amount of fine aggregate and fine powder is added at a rate of 32%-38%. The amount of the cementitious material is 13%-17%, the amount of water is 5.2%-8.5%, and the amount of the admixture is less than 1%.

8. The method for recycling decommissioned wind turbine blades according to claim 4, characterized in that, The concrete material is grade C15-C25, and the amount of blocky coarse fiber particles is 0.8%-1% by volume fraction of the concrete, and the total amount of coarse aggregate and blocky coarse fiber particles is 30%-37%. The fine powder is added at a rate of 12%-15%, and the total amount of fine aggregate and fine powder is 35%-42%. The amount of the cementitious material is 10%-14%, the amount of water is 5%-8.4%, and the amount of the admixture is less than 1%.

9. The method for recycling decommissioned wind turbine blades according to claim 4, characterized in that, The coarse aggregate has a particle size of 5-25 mm, and the fine aggregate has a particle size of 0.16-5 mm.

10. The method for recycling decommissioned wind turbine blades according to claim 4, characterized in that, The concrete material was poured using a high-frequency wall-mounted vibrator.

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