Grouting material for offshore wind power foundation structure and preparation method thereof

Abstract

The invention provides a grouting material for an offshore wind power foundation structure and a preparation method of the grouting material, and relates to the technical field of cement-based grouting materials. The grouting material comprises a solid raw material and a liquid raw material, the solid raw material comprises a diversified gel material system, straight steel fibers, hook-end steel fibers and auxiliaries, and the diversified gel material system is mainly composed of Portland cement, high-activity silica fume, fly ash microspheres, superfine limestone powder, superfine slag powder and quartz sand; the auxiliary agent comprises a chemical additive and a bio-based self-repairing agent. The grouting material has the technical effects of high early-stage and later-stage strength, high elastic modulus, excellent corrosion resistance, good environmental protection property and self-repairing function, solves the problems of environmental adaptation and structural maintenance of offshore wind power foundation structures, can bear complex and irregular impact load on the sea, can resist corrosion of seawater, and has the advantages of high strength, high elasticity modulus, excellent corrosion resistance and good self-repairing performance. And micro cracks are self-repaired, and the harsh application requirements of offshore wind power engineering are better met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cement-based grouting materials, in particular to a grouting material for offshore wind power foundation structures and a preparation method thereof. BACKGROUND

[0002] With the growing demand for renewable energy worldwide, offshore wind power has received widespread attention and vigorous development as a clean, efficient and sustainable form of energy. Offshore wind power not only provides stable power supply, but also effectively reduces greenhouse gas emissions, helping to achieve global climate change goals. However, the construction and maintenance of offshore wind power facilities face complex marine environmental challenges, especially in the connection and fixation of foundation structures, which have extremely stringent performance requirements for grouting materials.

[0003] Offshore wind power facilities are exposed to seawater, waves, salt spray and marine organisms for a long time. These environmental factors pose a great challenge to the foundation structure of the wind power facility, requiring grouting materials to have high strength, high durability, high fluidity and good corrosion resistance. Domestic and foreign scholars and engineering and technical personnel have carried out a lot of work on the preparation and performance of high-performance offshore wind power grouting materials. Research content involves material composition and ratio optimization, preparation process and construction technology, performance testing and evaluation methods, and other aspects. By reasonably selecting the type of cement, adding fly ash and mineral powder and other active admixtures, and using high-efficiency water reducing agents and other admixtures, the comprehensive performance of the grouting material can be significantly improved. In addition, the application of multi-scale design and simulation, environmental adaptability and long-term performance evaluation, and other frontier technologies also provides new ideas and methods for the research and development of high-performance grouting materials.

[0004] Despite the significant progress made, the research and application of high-performance offshore wind power grouting materials still face some challenges, such as the balance between material cost and economic benefit, the optimization of construction technology and quality control, the evaluation of long-term performance and environmental impact, etc.

[0005] Therefore, it is of great significance to research and develop a multi-element cementitious material system offshore wind power grouting material with excellent workability, mechanical properties, corrosion resistance and self-repairing function for promoting the development of offshore wind power industry.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The first object of the present application is to provide a grouting material for offshore wind power foundation structures, which has good workability, micro-expansion characteristics, and high early and late strength, high elastic modulus, and excellent durability. Compared with conventional grouting material products, the material has excellent comprehensive performance and is more suitable for the harsh application requirements of offshore wind power engineering.

[0008] The second objective of this invention is to provide a method for preparing grouting materials for offshore wind power foundation structures.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: This invention provides a grouting material for offshore wind power foundation structures, the grouting material comprising solid raw materials and liquid raw materials; The solid raw materials include: a diversified gel material system, straight steel fibers, hooked steel fibers, and additives, wherein: The diversified gel material system is mainly composed of silicate cement, highly active silica fume, fly ash microspheres, ultrafine limestone powder, ultrafine slag powder and quartz sand. The additives include chemical admixtures and bio-based self-healing agents. The bio-based self-healing agent is a microbial self-healing agent using guar soybean powder as a carrier. Guar soybean powder is mixed with *Bacillus pasteurellii* spore fermentation broth, urea, and calcium chloride solution to form a slurry, which is then freeze-dried to produce a uniform composite powder. The guar soybean powder has a galactomannan molecular network structure with a particle size distribution of D50 ≤ 75 μm and D90 ≤ 150 μm; the *Bacillus pasteurellii* spore fermentation broth should have a spore concentration ≥ 10. 9 CFU / mL; The highly reactive silica fume has a SiO2 content >93% and a density of 2.05 g / cm³. 3 The average particle size is 0.1 μm ~ 0.2 μm, and the specific surface area is >22000 m². 2 / kg; The straight steel fibers account for 1-2% of the solid raw materials, and the straight steel fibers have a diameter of 0.20-0.22 mm, a length of 11-12 mm, and a density of 7800-7850 kg / m³. The proportion of the hooked steel fiber in the solid raw material is 1~2%, the diameter of the hooked steel fiber is 0.20~0.22mm, the length is 11~12mm, and the density is 7800~7850 kg / m³.

[0010] The liquid raw material is water.

[0011] Furthermore, the mass ratio of the liquid raw material to the solid raw material is 0.08~0.09:1.

[0012] Furthermore, the additives include water-reducing agents, defoamers, expanding agents, and rust inhibitors; Preferably, the water-reducing agent is PC-1006 polycarboxylate powder water-reducing agent; Preferably, the defoamer is a powdered solid mineral oil-based defoamer; Preferably, the expanding agent is an EP 2 type plastic expanding agent; Preferably, the rust inhibitor is DC-1008 with internally incorporated migration-type rust inhibitor (MCI).

[0013] Preferably, the bio-based self-healing agent is a light yellow to light brown porous powder with a main particle size distribution between 150 and 180 μm, a moisture content of ≤5%, a bulk density between 0.35 and 0.50 g / cm³, and an angle of repose of ≤40°, exhibiting excellent dry flowability and easy uniform mixing with cementitious materials in a dry powder state. Its core function lies in loading highly active microbial spores, with a spore survival rate of ≥70% and an annual activity decay rate of ≤10% under dry and sealed storage conditions at 4℃. After activation by water, this powder can effectively induce calcium carbonate precipitation in a simulated concrete pore fluid environment, exhibiting significant biomineralization ability. Tests were conducted with an internal admixture dosage of 2.0% of the total mass of the solid raw materials in the grouting material. Under 28-day standard curing conditions, this material can achieve efficient self-healing of cracks with a width not exceeding 0.3 mm, and the impermeability of the repaired specimen can be restored to more than 80% of the baseline value.

[0014] Furthermore, the bio-based self-healing agent mainly comprises three parts: a specific bacterial strain (Bacillus pasteurellii), a nutrient source (urea, calcium chloride), and a carrier (guar bean powder). Its preparation process mainly includes steps such as dry mixing of materials, low-temperature slurry preparation, rapid freezing and molding, freeze-drying, pulverization, and packaging. Specifically, firstly, under low-temperature and stirring conditions, the dry mixture of guar bean powder and trehalose is slowly added to deionized water cooled to 4±2℃ to form a uniform basic gel. The mass ratio of guar bean powder to deionized water is 1:(15-20), and the amount of trehalose added is 1-2% of the dry weight of the guar bean powder. Subsequently, under continuous ice bath cooling to maintain the slurry temperature below 10℃, a pre-cooled mixed solution of urea and calcium chloride, as well as a suspension of Bacillus pasteurellii spores, are sequentially added to the basic gel, and the mixture is adjusted... The pH of the slurry was adjusted to 7.0-7.5 to obtain a homogeneous composite slurry with a total solid content of 10-15%, wherein the molar ratio of urea to calcium chloride was controlled at 1.0:(1.0-1.2). Then, the composite slurry was rapidly deep-frozen and transferred to a freeze dryer, where it underwent a low-temperature primary drying process followed by a heated secondary drying process to finally obtain a dry porous solid with a moisture content of less than 5%. Finally, the solid was pulverized, sieved, and sealed in a dry environment to obtain the desired microbial self-healing composite powder.

[0015] Furthermore, based on parts by mass, the solid raw material comprises the following components: 32.5-42.5 parts silicate cement, 2.5-6.5 parts high-activity silica fume, 1-2 parts fly ash microspheres, 1.5-4.5 parts ultrafine limestone powder, 2.5-5.5 parts ultrafine slag powder, 50-60 parts quartz sand, 0.7-1.1 parts water-reducing agent, 0.07-0.2 parts defoamer, 1.5-2 parts rust inhibitor, 0.5-1.5 parts bio-based self-healing agent, 0.2-1.2 parts expansion agent, 1.7-2.0 parts straight steel fiber, and 1.7-2.0 parts hooked steel fiber.

[0016] Furthermore, the specific surface area of ​​the ultrafine limestone powder is 500-700 m². 2 / kg; Furthermore, the density of the ultrafine slag powder is 2.86 g / cm³. 3 Specific surface area is 600-800 m² 2 / kg; Furthermore, the fly ash microspheres are spherical glassy particles with a particle size of 4-5 μm and a specific surface area of ​​900 m². 2 / kg; Furthermore, the silicate cement is P.II52.5 silicate cement.

[0017] Furthermore, the quartz sand is a three-graded quartz sand system, and the gradation percentage of the quartz sand aggregate is: 2.00mm~0.59mm: 54%; 0.60mm~0.27mm: 23%; 0.28mm~0.10mm: 23%.

[0018] Furthermore, the bio-based self-healing agent is a light yellow to light brown porous powder with a main particle size distribution between 150 and 180 μm, a moisture content of ≤5%, a bulk density between 0.35 and 0.50 g / cm³, and an angle of repose of ≤40°, exhibiting excellent dry flowability and easy uniform mixing with cementitious materials in a dry powder state. Its core function lies in loading highly active microbial spores, with a spore survival rate of ≥70% and an annual activity decay rate of ≤10% under dry and sealed storage conditions at 4℃. After activation by water, this powder can effectively induce calcium carbonate precipitation in a simulated concrete pore fluid environment, exhibiting significant biomineralization ability. Tests were conducted with an internal admixture dosage of 2.0% of the total mass of the solid raw materials in the grouting material. Under 28-day standard curing conditions, this material can achieve efficient self-healing of cracks with a width not exceeding 0.3 mm, and the impermeability of the repaired specimen can be restored to more than 80% of the baseline value.

[0019] The present invention provides a method for preparing the above-mentioned grouting material, the method comprising: Weigh the solid raw materials according to the mass fractions, mix them evenly to obtain a solid material, add the liquid raw material water to the solid material and stir to form a slurry to obtain the grouting material.

[0020] Furthermore, the method of stirring into a slurry includes: Stir the solid material at a slow speed for 1-2 minutes, then add liquid raw material water and stir for 2-3 minutes. Then increase the stirring speed and stir at a fast speed for 5-6 minutes.

[0021] Furthermore, the rotation speed of the slow stirring is 135~145 rpm, the revolution speed is 57~67 rpm, and the temperature is 20~25℃; Furthermore, the rotation speed of the rapid stirring is 275~295 rpm, the revolution speed is 115~135 rpm, and the temperature is 20~25℃.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The grouting material for offshore wind power foundations provided by this invention is composed of the raw materials of this grouting material. This grouting material for offshore wind power foundations not only possesses excellent workability and micro-expansion characteristics, but also exhibits high early and late strength, high elastic modulus, and excellent durability. Furthermore, it partially replaces chemical additives with a bio-based grouting modifier, resulting in green, environmentally friendly, and economical benefits. Compared to conventional grouting products, the grouting material of this application has superior comprehensive performance, capable of withstanding complex and irregular impact loads at sea and resisting seawater erosion, thus better meeting the stringent application requirements of offshore wind power projects.

[0023] It should be noted that the bio-based self-healing agent of this application is prepared by mixing guar bean powder with Bacillus pasteurellium spore fermentation broth, urea, and calcium chloride solution to form a slurry, which is then freeze-dried. The preparation process includes steps such as dry mixing of materials, low-temperature slurry preparation, rapid freezing and molding, freeze-drying, pulverization and packaging (see Example 1 for details). In the grouting material of this application, the galactomannan molecular network structure of the bio-based self-healing agent can effectively "lock" in free water, giving the grouting material good water retention, ensuring full hydration, reducing shrinkage, and providing a stable microenvironment for spore activation, germination and subsequent biochemical reactions. At the same time, it has good compatibility with polycarboxylate superplasticizers. The superplasticizer is responsible for dispersing cement particles and releasing free water, while the galactomannan is responsible for stabilizing the released water and the newly formed suspension system. The two work synergistically to give the grouting material good workability and stability. By incorporating dormant Pasteurella spores and nutrients into the grouting material using guar soybean flour, the microorganisms are activated when microcracks appear and seawater seeps in. The galactomannan in the guar soybean flour is gradually broken down into monosaccharides by microbial enzymes, providing the microorganisms with the sustained energy needed for growth and urease production. Ultimately, calcium carbonate is produced at the cracks, automatically "healing" the damage. This can significantly extend the service life of deep-sea wind turbine foundations, which are difficult to maintain manually.

[0024] The present invention provides a method for preparing grouting materials. The method first involves mixing solid raw materials to obtain a solid material, then adding liquid raw material (water) to the solid material and stirring to form a slurry to obtain the grouting material. This preparation method has the advantages of simple and efficient processing, and is suitable for both factory production and on-site preparation. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The images show actual straight steel fibers and hooked steel fibers in the solid raw materials of this invention. Figure 2 This is a diagram of the galactomannan molecular network structure of the bio-based grout modifier in this invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] According to one aspect of the present invention, a grouting material for offshore wind power foundation structures, the grouting material comprising solid raw materials and liquid raw materials; The solid raw materials include: a diversified gel material system, straight steel fibers, hooked steel fibers, and additives, wherein: The diversified gel material system is mainly composed of silicate cement, highly active silica fume, fly ash microspheres, ultrafine limestone powder, ultrafine slag powder and quartz sand. The additives include chemical admixtures and bio-based self-healing agents. The bio-based self-healing agent is a microbial self-healing agent using guar soybean powder as a carrier. Guar soybean powder is mixed with *Bacillus pasteurellii* spore fermentation broth, urea, and calcium chloride solution to form a slurry, which is then freeze-dried to produce a uniform composite powder. The guar soybean powder has a galactomannan molecular network structure with a particle size distribution of D50 ≤ 75 μm and D90 ≤ 150 μm; the *Bacillus pasteurellii* spore fermentation broth should have a spore concentration ≥ 10. 9 CFU / mL; The highly reactive silica fume has a SiO2 content >93% and a density of 2.05 g / cm³. 3 The average particle size is 0.1 μm ~ 0.2 μm, and the specific surface area is >22000 m². 2 / kg; The straight steel fibers account for 1-2% of the solid raw materials, and the straight steel fibers have a diameter of 0.20-0.22 mm, a length of 11-12 mm, and a density of 7800-7850 kg / m³. The proportion of the hooked steel fiber in the solid raw material is 1~2%, the diameter of the hooked steel fiber is 0.20~0.22mm, the length is 11~12mm, and the density is 7800~7850 kg / m³.

[0029] The liquid raw material is water.

[0030] The grouting material for offshore wind power foundation structures provided by this invention comprises, as its solid raw materials, a diversified gel material system, straight steel fibers, hooked steel fibers, and additives, wherein: The diversified gel material system, through the multi-component composite of ultrafine slag powder, ultrafine limestone powder, fly ash microspheres, silicate cement, and highly active silica fume, achieves a multi-scale synergistic effect of physical filling and chemical activity activation, significantly improving the performance of the grouting material. Specifically: 1. The complementary activity of ultrafine slag powder and ultrafine limestone powder in co-admixture. Ultrafine slag powder exhibits significant pozzolanic activity, undergoing a pozzolanic reaction to generate low-calcium CSH gel, consuming CH4 and thus improving density and later-stage strength. Ultrafine limestone powder, on the other hand, is an inert admixture with no pozzolanic activity. Its main function is to optimize particle size distribution through physicochemical processes. Simultaneously, its surface CaCO3 can react with C3A in cement to form aluminocarbonates, accelerating hydration and refining the pore structure. The pozzolanic reaction of slag powder consumes CH4, while the aluminocarbonation reaction of limestone powder provides additional nucleation sites. The interaction between these two mineral admixtures with different activities increases the chemical interaction and induction of particles in the system, thereby enhancing the chemical activity of the powder.

[0031] 2. Ultrafine slag powder, ultrafine limestone powder, fly ash microspheres, and highly active silica fume have different particle sizes. The combined blending of particles of different sizes allows for denser particle packing, reducing pore structure and promoting the development of grout strength. This creates a high-density, low-defect hardened structure at the microscale, while at the macroscale, the grout possesses high strength, high durability, and high rheological stability. Figure 1 The images show actual straight steel fibers and hooked steel fibers in the solid raw materials of this invention.

[0032] See Figure 1 The addition of straight and hooked steel fibers in this application significantly improves the toughness, impact resistance, and fatigue resistance of the grout, making it more suitable for offshore wind turbine foundations that need to withstand dynamic loads. Specifically, the straight steel fibers in the grout enhance the interfacial bonding with the matrix through mechanical interlocking force, while the hooked steel fibers provide higher pull-out resistance due to their end anchoring effect. The synergy of the two can effectively optimize the load transfer efficiency of the grout. At the same time, the straight and hooked steel fibers are uniformly dispersed in the matrix of the offshore wind turbine foundation structure to form a three-dimensional mesh support structure, which can effectively bridge cracks, delay crack propagation, and absorb energy, thereby improving the crack resistance and toughness of the matrix.

[0033] Furthermore, the applicant would like to emphasize that the high-activity silica fume of this application is an ultrafine, amorphous powder material with a high specific surface area, obtained by oxidizing gaseous SiO to form SiO2 vapor in a high-temperature zone of 2000℃ during the high-temperature smelting of ferrosilicon alloys or industrial silicon in an electric arc furnace, followed by rapid cooling and condensation in a low-temperature zone of 1100℃, and then collecting it through a high-efficiency dust collection device. Therefore, the high-activity silica fume described in this application has an SiO2 content >93% and a density of 2.05 g / cm³.3 Specific surface area > 22000 m² 2 / kg; tests showed that the addition of the above-mentioned highly active silica fume had a significant impact on the performance of the final grouting material.

[0034] This application does not have specific restrictions on the source of highly reactive silica fume; it can use silica fume with SiO2 content > 93% and density 2.05 g / cm³. 3 Specific surface area > 22000 m² 2 Highly active silica fume meeting the requirements of / kg is sufficient.

[0035] Therefore, the grouting material of this application, derived from its raw material composition, not only possesses excellent workability and micro-expansion characteristics, but also exhibits high early and late strength, high elastic modulus, and superior durability. Compared to conventional grouting products, the grouting material of this application boasts superior comprehensive performance, capable of withstanding complex and irregular impact loads at sea and resisting seawater erosion, thus better meeting the stringent application requirements of offshore wind power projects.

[0036] Specifically, the grouting material of this invention for offshore wind power foundation structures has been tested and verified to have the following excellent properties: initial flowability ≥300mm, 30min flowability ≥270mm; 1-day compressive strength ≥45MPa, 3-day compressive strength ≥70MPa, 28-day compressive strength ≥125MPa; 1-day flexural strength ≥10MPa, 3-day flexural strength ≥16MPa, 28-day flexural strength ≥23MPa; 3-hour vertical expansion rate 0.2%~0.9%, difference between 24-hour and 3-hour vertical expansion rate 0.02%~0.50%; static compressive modulus of elasticity ≥45GPa; freeze-thaw resistance grade F900 or higher; chloride ion diffusion coefficient ≤1.0×10 -12 m² / s; 1-day water-land intensity ratio ≥80%, 3-day water-land intensity ratio ≥90%, 28-day water-land intensity ratio ≥90%; chloride ion content ≤0.06%.

[0037] In a preferred embodiment of the present invention, the mass ratio of the liquid raw material to the solid raw material is 0.08~0.09:1.

[0038] As a preferred embodiment, excessive liquid raw material will lead to a decrease in slurry cohesion, resulting in stratification and bleeding, a significant reduction in strength, increased porosity, accelerated chloride ion penetration, damage to freeze-thaw resistance and fatigue resistance, and serious harm to durability. Excessive solid raw material will cause a sharp increase in slurry viscosity, loss of fluidity, and during the slurry hardening process, the hardened body will generate shrinkage stress due to lack of water, resulting in structural microcracks, hardening shrinkage and cracking.

[0039] In a preferred embodiment of the present invention, the chemical additives include water-reducing agents, defoamers, expanding agents, and rust inhibitors; Preferably, the water-reducing agent is PC-1006 polycarboxylate powder water-reducing agent; the defoamer is powdered solid mineral oil-based defoamer; the expanding agent is EP 2 type plastic expanding agent; and the rust inhibitor is DC-1008 internally mixed migration type rust inhibitor (MCI). It should be noted that the present invention adds a migratory rust inhibitor to the grouting material, which utilizes its active migration and penetration characteristics to produce a synergistic effect with straight steel fibers and hooked steel fibers. This enables the straight steel fibers, hooked steel fibers and the surface of the reinforcing bars to form a dense protective film, blocking the electrochemical corrosion reaction caused by chloride ion erosion, and significantly enhancing the long-term durability and structural service safety of the grouting material in highly corrosive environments such as marine and saline environments.

[0040] In a preferred embodiment of the present invention, the bio-based self-healing agent has a galactomannan molecular network structure, and its preparation process includes raw material processing, endosperm separation and refining and pulverizing steps.

[0041] Figure 2 This is a diagram of the galactomannan molecular network structure of the bio-based self-healing agent in this invention.

[0042] See Figure 2 The galactomannan molecular network structure of the bio-based self-healing agent effectively "locks in" free water, giving the grout excellent water retention, ensuring full hydration, reducing shrinkage, and providing a stable microenvironment for spore activation, germination, and subsequent biochemical reactions. Simultaneously, it exhibits good compatibility with polycarboxylate superplasticizers. The superplasticizer disperses cement particles and releases free water, while the galactomannan stabilizes the released water and the newly formed suspension system. The two work synergistically, giving the grout excellent workability and stability. By incorporating dormant Bacillus pasteurellii spores and nutrients into the grout using guar soybean powder, when microcracks appear later and seawater seeps in, the microorganisms are activated. The galactomannan in the guar soybean powder is gradually broken down into monosaccharides by microbial enzymes, providing the sustained energy needed for microbial growth and urease production. Ultimately, calcium carbonate is produced at the cracks, automatically "healing" the damage. This can significantly extend the service life of deep-sea wind power foundations, which are difficult to maintain manually.

[0043] Preferably, the bio-based self-healing agent is a light yellow to light brown porous powder with a main particle size distribution between 150 and 180 μm, a moisture content of ≤5%, a bulk density between 0.35 and 0.50 g / cm³, and an angle of repose of ≤40°, exhibiting excellent dry flowability and easy uniform mixing with cementitious materials in a dry powder state. Its core function lies in loading highly active microbial spores, with a spore survival rate of ≥70% and an annual activity decay rate of ≤10% under dry and sealed storage conditions at 4°C.

[0044] In a preferred embodiment of the present invention, the solid raw material comprises the following components by mass parts: 32.5-42.5 parts silicate cement, 2.5-6.5 parts high-activity silica fume, 1-2 parts fly ash microspheres, 1.5-4.5 parts ultrafine limestone powder, 2.5-5.5 parts ultrafine slag powder, 50-60 parts quartz sand, 0.7-1.1 parts water-reducing agent, 0.07-0.2 parts defoamer, 0.2-1.2 parts expansion agent, 1.5-2 parts rust inhibitor, 0.5-1.5 parts bio-based self-healing agent, 1.7-2.0 parts straight steel fiber, and 1.7-2.0 parts hooked steel fiber.

[0045] As a preferred embodiment, the grouting material obtained by compounding the above-mentioned mass proportions has high strength, high durability, high fluidity and good corrosion resistance, which can fully meet the requirements of offshore wind power facilities.

[0046] In some specific embodiments, by weight, silicate cement includes, but is not limited to, a point value or a range between any two of 32.5 parts, 35 parts, 37.5 parts, 40 parts, or 42.5 parts; highly active silica fume includes, but is not limited to, a point value or a range between any two of 2.5 parts, 3.5 parts, 4.5 parts, 5.5 parts, or 6.5 parts; fly ash microspheres include, but are not limited to, a point value or a range between any two of 1 part, 1.5 parts, or 2 parts; ultrafine limestone powder includes, but is not limited to, a point value or a range between any two of 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4.5 parts; and ultrafine slag powder includes, but is not limited to, a point value or a range between any two of 2.5 parts, 3 parts, 4 parts, 4.5 parts, or 5.5 parts. In some specific embodiments, by weight, the quartz sand includes, but is not limited to, any one of 50 parts, 53 parts, 55 parts, 57 parts or 60 parts, or a range of any two of them. In some specific embodiments, by weight, the water-reducing agent includes, but is not limited to, a point value or a range between any two of any one of 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, or 1.1 parts; the defoamer includes, but is not limited to, a point value or a range between any two of any one of 0.07 parts, 0.09 parts, 0.12 parts, 0.18 parts, or 0.2 parts; the plasticizing agent includes, but is not limited to, a point value or a range between any two of any one of 0.2 parts, 0.6 parts, 0.8 parts, or 1.2 parts; the rust inhibitor includes, but is not limited to, a point value or a range between any two of any one of 1.5 parts, 1.6 parts, 1.8 parts, 1.9 parts, or 2.0 parts; and the bio-based self-healing agent includes, but is not limited to, a point value or a range between any two of any one of 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, or 1.5 parts.

[0047] In some specific embodiments, the straight steel fibers and the hooked steel fibers, by weight, include, but are not limited to, point values ​​of any one of 1.7 parts, 1.8 parts, 1.9 parts, or 2.0 parts, or range values ​​between any two.

[0048] In a preferred embodiment of the present invention, the silicate cement is P.II52.5 silicate cement.

[0049] In a preferred embodiment of the present invention, the specific surface area of ​​the ultrafine limestone powder is 500-700 m². 2 / kg; the density of the ultrafine slag powder is 2.86 g / cm³. 3 Specific surface area is 600-800 m² 2 / kg; As a preferred embodiment, this application employs two mineral admixtures with different activities—ultrafine limestone powder and ultrafine slag powder—to mutually enhance the pozzolanic effect, increasing the chemical interaction and induction activation between particles in the system, thereby improving the chemical activity of the powder. In some specific embodiments, the specific surface area of ​​the ultrafine limestone powder includes, but is not limited to, 500 m². 2 / kg, 550m 2 / kg, 600m 2 / kg or 700m 2 / kg is a point value of any one of them or a range of values ​​between any two; the surface area of ​​ultrafine slag powder is including but not limited to 600m². 2 / kg, 650m 2 / kg, 700m 2 A point value of either / kg or 800m2 / kg, or a range of values ​​between the two; In a preferred embodiment of the present invention, the fly ash microspheres are spherical glassy particles with a particle size of 4-5 μm and a specific surface area of ​​920 m².2 / kg; In one preferred embodiment, the fly ash microspheres are hollow microspheres containing nitrogen and carbon dioxide gases, obtained from fly ash raw materials from large-scale thermal power plants using supercritical extraction technology through separation, processing, and purification. They are highly active spherical glassy bodies formed at 1500℃. Due to their smooth and rounded shape and small particle size, these fly ash microspheres can act as "ball bearings" and dense fillers in grouting materials, improving the fluidity of the grouting material, reducing hydration heat release, and improving the pore structure, resulting in a denser hardened cement paste. In some specific embodiments, the particle size of the fly ash microspheres includes, but is not limited to, a value of any one of 4μm, 4.5μm, or 5μm, or a range between any two.

[0050] The fly ash used in this application was obtained by the Qiangdong Mineral Products Processing Plant in Lingshou County through the above-mentioned process using fly ash from a large thermal power plant as raw material. It has a particle size of 4-5 μm and a specific surface area of ​​920 m². 2 The highly active spherical glass particles per kg have a smooth and glossy shape and a small particle size. In grout, they can act as "balls" and dense fillers, improving the fluidity of the grout, reducing the heat of hydration, and improving the pore structure, making the hardened cement paste more compact.

[0051] In a preferred embodiment of the present invention, the quartz sand is a three-graded quartz sand system, and the gradation percentage of the quartz sand aggregate is: 2.00mm~0.59mm: 54%; 0.60mm~0.27mm: 23%; 0.28mm~0.10mm: 23%.

[0052] As a preferred embodiment, the above-described three-graded quartz sand system of this application has been verified to have good working performance and mechanical properties.

[0053] According to one aspect of the present invention, a method for preparing the above-mentioned grouting material, the method comprising: Weigh the solid raw materials according to the mass fractions, mix them evenly to obtain a solid material, add the liquid raw material water to the solid material and stir to form a slurry to obtain the grouting material.

[0054] The present invention provides a method for preparing grouting materials. The method first involves mixing solid raw materials to obtain a solid material, then adding liquid raw material (water) to the solid material and stirring to form a slurry to obtain the grouting material. This preparation method has the advantages of simple and efficient processing, and is suitable for both factory production and on-site preparation.

[0055] In a preferred embodiment of the present invention, the method of stirring into a slurry includes: stirring the solid material at a slow stirring speed for 1 to 2 minutes, then adding liquid raw material water and stirring for 2 to 3 minutes, and then increasing the stirring speed and stirring at a fast stirring speed for 5 to 6 minutes.

[0056] In the above preferred embodiment, the slow stirring has a rotation speed of 135~145 rpm, a revolution speed of 57~67 rpm, and a temperature of 20~25℃; the fast stirring has a rotation speed of 275~295 rpm, a revolution speed of 115~135 rpm, and a temperature of 20~25℃.

[0057] The technical solution of the present invention will be further described below with reference to the embodiments.

[0058] In the following examples and comparative examples, the amounts of each raw material are parts by weight. The manufacturers and models of the raw materials used are shown in Table 1. Raw materials not listed in Table 1 were all purchased from commercially available sources.

[0059] Table 1:

[0060] Examples 1-5 A grouting material for offshore wind power foundation structures, wherein the solid phase raw material composition of the grouting material is shown in Table 2.

[0061] Table 2:

[0062] In the above embodiments, the highly reactive silica fume has a SiO2 content > 93% and a density of 2.05 g / cm³. 3 The average particle size is 0.1 μm ~ 0.2 μm, and the specific surface area is >22000 m². 2 / kg; The specific surface area of ​​the ultrafine limestone powder is 500~700 m². 2 / kg, with a fineness of 1200~1300 mesh; The density of the ultrafine slag powder is 2.86 g / cm³. 3 Specific surface area is 600~800 m² 2 / kg, average particle size 6.0μm; The fly ash microspheres are spherical glassy particles with a particle size of 4-5 μm and a specific surface area of ​​900 m². 2 / kg; The quartz sand is a three-graded quartz sand system, and the gradation percentage of the quartz sand aggregate is: 2.00mm~0.59mm: 54%; 0.60mm~0.27mm: 23%; 0.28mm~0.10mm: 23%.

[0063] The straight steel fibers have a diameter of 0.20~0.22mm, a length of 11~12mm, and a density of 7800~7850 kg / m³. The hook-shaped steel fiber has a diameter of 0.20~0.22mm, a length of 11~12mm, and a density of 7800~7850 kg / m³.

[0064] The preparation method of the bio-based self-healing agent in this embodiment includes the following steps: 1. Under low temperature and continuous mechanical stirring, slowly and evenly add the dry mixture of guar bean powder and trehalose to deionized water cooled to 4±2℃, controlling the mass ratio of guar bean powder to deionized water to be 1:(15-20), and the amount of trehalose added is 1-2% of the dry weight of guar bean powder. Continue stirring until a homogeneous, viscous base gel without visible particles is formed.

[0065] 2. Place the container containing the base gel in an ice-water bath to ensure the slurry temperature remains below 10°C throughout the subsequent operations. While continuously stirring at low speed, first add the pre-prepared and cooled urea and calcium chloride mixture, followed by the slow addition of the *Bacillus pasteurellii* spore suspension. After the addition is complete, adjust the pH of the slurry to 7.0-7.5 using a dilute acid or alkali solution to obtain a homogeneous composite slurry with a total solids content of 10-15%. The molar ratio of urea to calcium chloride should be controlled at 1.0:(1.0-1.2).

[0066] 3. Quickly transfer the above composite slurry into a shallow dish, ensuring the slurry is spread to a thickness not exceeding 10 mm, and immediately place it in an ultra-low temperature environment of -40℃ to -80℃ for rapid deep freezing until it is completely solidified.

[0067] 4. Transfer the frozen solid to a pre-cooled freeze dryer. First, perform primary drying at low temperature (e.g., -40℃ to -20℃) and high vacuum (≤30 Pa) for a sufficient time to sublimate and remove most of the free water. Then, gradually increase the temperature to 25-30℃ for secondary drying to remove residual bound water, finally obtaining a porous dry solid with a moisture content of less than 5%.

[0068] 5. In a dry environment, gently pulverize the freeze-dried porous solid and sieve it through an 80-100 mesh screen. Place the resulting uniform powder in a sealed container with a built-in desiccant to equilibrate the moisture content, then immediately seal it in a moisture-proof and light-proof package and store it at a low temperature.

[0069] The prepared bio-based self-healing agent is a light yellow to light brown porous powder with a main particle size distribution between 150 and 180 μm, a moisture content of ≤5%, a bulk density between 0.35 and 0.50 g / cm³, and an angle of repose of ≤40°, exhibiting excellent dry flowability and easy uniform mixing with gelling materials in a dry powder state. The spore survival rate is ≥70%, and the annual activity decay rate is ≤10% under dry and sealed storage conditions at 4℃.

[0070] The method for preparing the grouting material includes the following steps: The solid raw material was stirred at a slow speed for 2 minutes, then the liquid raw material water was added and stirred for 2 minutes. Then the stirring speed was increased and stirred at a fast speed for 5 minutes to obtain the grouting material. Wherein: the mass ratio of liquid raw material water to solid raw material is 0.08~0.09:1; the rotation speed of the slow stirring is 140 rpm, the revolution speed is 65 rpm, and the temperature is 20℃; the rotation speed of the fast stirring is 285 rpm, the revolution speed is 125 rpm, and the temperature is 20℃.

[0071] Comparative Examples 1-9 A grouting material for offshore wind power foundation structures, wherein the solid phase raw material composition of the grouting material is shown in Tables 3 and 4.

[0072] Table 3:

[0073] Table 4:

[0074] Note: The “-” in Tables 3 and 4 above indicates the same as in Example 1.

[0075] The preparation method of the grouting material is the same as in Example 1.

[0076] Comparative Example 11 The difference between this comparative example and Example 1 is that the Runfeng brand P.II52.5 silicate cement produced by China Resources Company was replaced with Dunshi brand P·O52.5 cement produced by Tangshan Jidong Cement Co., Ltd.

[0077] Comparative Example 12 The difference between this comparative example and Example 1 is that the high-activity silica fume was replaced with a common silica fume from the building materials market, whose 28-day activity index is 105%. Comparative Example 13 The difference between this comparative example and Example 1 is that the fly ash microspheres were replaced with ordinary fly ash from a building materials market, which has a 28-day activity index of 70%. Comparative Example 14 The difference between this comparative example and Example 1 is that: ultrafine limestone powder is replaced with ordinary limestone powder, with a specific surface area of ​​350 m2 / kg; ultrafine slag powder is replaced with ordinary slag powder, with a specific surface area of ​​400 m2 / kg. Comparative Example 15 The difference between this comparative example and Example 1 is that the aggregate gradation percentage of the three-graded quartz sand system used is: 2.00mm~0.60mm:47%, 0.60mm~0.28mm:25%, 0.28mm~0.10mm:28%.

[0078] Comparative Example 16 This comparative example is identical to Example 1 except that "the mass ratio of liquid raw material water to solid raw material is 0.15:1 during the preparation of grouting material".

[0079] Experimental Example 1 The grouting materials obtained in Examples 1-5 and Comparative Examples 1-16 were subjected to performance tests. The test methods for mortar fluidity and vertical expansion rate were in accordance with GB / T50448-2015 "Technical Specification for Application of Cement-based Grouting Materials", the test methods for air content and bleeding rate were in accordance with GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", and the test methods for compressive strength and flexural strength were in accordance with GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)".

[0080] The specific experimental results are shown in Tables 5 to 7: Table 5:

[0081] Table 6:

[0082] Table 7:

[0083] As can be seen from the above, the grouting materials provided in Examples 1 to 5 of the present invention, through the synergistic effect of a multi-component cementitious material system, high-performance admixtures and steel fiber reinforcement, and after a reasonable preparation method, possess both high strength and excellent workability. Furthermore, after being immersed and cured in water for a certain period of time, the crack healing area ratio and compressive strength recovery rate are relatively high, meeting the stringent performance requirements of grouting materials in complex marine environments.

[0084] Comparative Examples 1 to 8 are comparative examples used to investigate the composition and content of raw materials in this application. Among them: Comparative Example 1 uses ultrafine slag powder alone, which significantly reduces early strength and slows down later strength growth. It lacks the micro-filling effect of ultrafine limestone powder, resulting in deteriorated particle size distribution and decreased density. At the same time, the hydration activity of slag powder alone is insufficient. Comparative Example 2 uses ultrafine limestone powder alone, which reduces mechanical strength and impermeability. Since limestone powder has no activity and only plays a filling role, it lacks the pozzolanic activity of slag powder, resulting in a loose slurry structure. In Comparative Example 3, the amount of water-reducing agent added was 0.4 parts. The fluidity decreased significantly, the porosity increased, the water demand increased, resulting in a higher water-cement ratio. After hardening, the internal defects increased, and the compressive strength and durability decreased significantly. In Comparative Example 4, the amount of defoamer added was 0.04 parts. The air content increased significantly, the density decreased, and the air bubbles in the hardened body could not be effectively eliminated, forming macroscopic pores, which led to a simultaneous decrease in compressive strength, frost resistance and impermeability. In Comparative Example 5, the amount of expansion agent added was 0.1 parts, the expansion rate decreased, the expansion in the plastic stage was insufficient and could not offset the settlement shrinkage, cracks were prone to appear after hardening, and the bonding strength between the steel fiber and the matrix interface decreased. In Comparative Example 6, the amount of rust inhibitor added was 1.0 part. The chloride ion diffusion coefficient increased, the hardened grout's ability to resist chloride ion corrosion was impaired, and its long-term durability and serviceability were significantly reduced.

[0085] Comparative Example 7: The amount of bio-based self-healing agent added was 0 parts. The expansion rate decreased, the later compressive and flexural strength decreased, the fluidity decreased, the impermeability decreased, and after a certain period of water immersion curing, the number of cracks increased significantly. Comparative Example 8, which uses only straight steel fibers, shows reduced toughness and crack resistance, lacks the anchoring effect of end-hooked fibers, and the fibers are easily pulled out when cracks propagate. In Comparative Example 9, which used only hook-shaped steel fibers, the fluidity was significantly reduced, falling below the specification requirements, and the viscosity of the freshly mixed material increased. In Comparative Example 11, the silicate cement of Example 1 was replaced with Dunshi brand P•O52.5 cement produced by Tangshan Jidong Cement Co., Ltd., resulting in a decrease in early strength, a slow development of strength, and an increase in long-term shrinkage. Comparative Example 12: Replacing the highly active silica fume with a common silica fume from the building materials market resulted in a decrease in overall strength. The common silica fume has low activity and large particle size, which cannot effectively fill the gaps in the cement, leading to a weakening of the interface transition zone, an increase in the chloride ion diffusion coefficient, and a decrease in durability. Comparative Example 13 replaced fly ash microspheres with ordinary fly ash from a building materials market. The water demand increased and the density decreased. Ordinary fly ash has an irregular morphology and high carbon content, which destroys the particle size distribution, resulting in faster loss of fluidity and decreased strength. Comparative Example 14 showed that replacing ultrafine limestone powder with ordinary limestone powder significantly increased porosity; The aggregate gradation of Comparative Example 15 is different from that of Example 1, resulting in water bleeding, reduced strength, increased porosity, and reduced bulk density, leading to insufficient slurry coating and an increase in weak interfacial areas. In Comparative Example 16, the implementation method with a mass ratio of liquid raw material water to solid raw material of 0.15:1 resulted in severe performance degradation, significant strength loss, and stratification of the slurry and aggregate.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grouting material for offshore wind power foundation structures, characterized in that, The grouting material includes solid raw materials and liquid raw materials; The solid raw materials include: a diversified gel material system, straight steel fibers, hooked steel fibers, and additives, wherein: The diversified gel material system is mainly composed of silicate cement, highly active silica fume, fly ash microspheres, ultrafine limestone powder, ultrafine slag powder and quartz sand. The additives include chemical admixtures and bio-based self-healing agents; The bio-based self-healing agent is a microbial self-healing agent with guar bean powder as a carrier. Guar bean powder is mixed with Bacillus pasteurellium spore fermentation broth, urea, and calcium chloride solution to form a slurry, which is then freeze-dried to produce a uniform composite powder. The guar flour has a galactomannan molecular network structure with a particle size distribution of D50 ≤ 75 μm and D90 ≤ 150 μm; the Bacillus pasteurellium spore fermentation broth should have a spore concentration ≥ 10. 9 CFU / mL; The highly reactive silica fume has a SiO2 content >93% and a density of 2.05 g / cm³. 3 The average particle size is 0.1μm~0.2μm, and the specific surface area is >22000m². 2 / kg; The straight steel fibers account for 1-2% of the solid raw materials, and the straight steel fibers have a diameter of 0.20-0.22 mm, a length of 11-12 mm, and a density of 7800-7850 kg / m³. The proportion of the hooked steel fiber in the solid raw material is 1~2%, the diameter of the hooked steel fiber is 0.20~0.22mm, the length is 11~12mm, and the density is 7800~7850 kg / m³. The liquid raw material is water.

2. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The mass ratio of the liquid raw material to the solid raw material is 0.08~0.09:

1.

3. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The chemical additives include water-reducing agents, defoamers, expanding agents, and rust inhibitors; Preferably, the water-reducing agent is PC-1006 polycarboxylate powder water-reducing agent; Preferably, the defoamer is a powdered solid mineral oil-based defoamer; Preferably, the expanding agent is an EP 2 type plastic expanding agent; Preferably, the rust inhibitor is DC-1008 internally mixed with a migration-type rust inhibitor; Preferably, the bio-based self-healing agent is a light yellow to light brown porous loose powder with a main particle size distribution between 150 and 180 μm, a moisture content of ≤5%, a bulk density between 0.35 and 0.50 g / cm³, and an angle of repose of ≤40°, exhibiting excellent dry flowability and easy to mix uniformly with cementitious materials in a dry powder state.

4. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The solid raw material comprises the following components by mass parts: 32.5-42.5 parts silicate cement, 2.5-6.5 parts high-activity silica fume, 1-2 parts fly ash microspheres, 1.5-4.5 parts ultrafine limestone powder, 2.5-5.5 parts ultrafine slag powder, 50-60 parts quartz sand, 0.7-1.1 parts water-reducing agent, 0.07-0.2 parts defoamer, 0.2-1.2 parts expansion agent, 1.5-2 parts rust inhibitor, 0.5-1.5 parts bio-based self-healing agent, 1.7-2.0 parts straight steel fiber, and 1.7-2.0 parts hooked steel fiber.

5. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The specific surface area of ​​the ultrafine limestone powder is 500-700 m². 2 / kg, with a fineness of 1200~1300 mesh; And / or, the density of the ultrafine slag powder is 2.86 g / cm³. 3 Specific surface area is 600-800 m² 2 / kg, average particle size 6.0μm; And / or, the fly ash microspheres are spherical glassy particles with a particle size of 4-5 μm and a specific surface area of ​​900 m². 2 / kg.

6. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The silicate cement is P.II52.5 silicate cement.

7. The grouting material for offshore wind power foundation structures according to claim 1, characterized in that, The quartz sand is a three-graded quartz sand system, with the following aggregate gradation percentages: 2.00mm~0.59mm: 54%; 0.60mm~0.27mm: 23%. 0.28mm~0.10mm: 23%.

8. A method for preparing a grouting material according to any one of claims 1 to 7, characterized in that, The preparation method includes: Weigh the solid raw materials according to the mass fractions, mix them evenly to obtain a solid material, add the liquid raw material water to the solid material and stir to form a slurry to obtain the grouting material.

9. The method for preparing the grouting material according to claim 8, characterized in that, The method of stirring into a slurry includes: Stir the solid raw material at a slow speed for 1-2 minutes, then add the liquid raw material water and stir for 2-3 minutes. Then increase the stirring speed and stir at a fast speed for 5-6 minutes.

10. The method for preparing the grouting material according to claim 9, characterized in that, The slow stirring has a rotation speed of 135~145 rpm, a revolution speed of 57~67 rpm, and a temperature of 20~25℃; The rapid stirring has a rotation speed of 275~295 rpm, a revolution speed of 115~135 rpm, and a temperature of 20~25℃.

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