Foamed concrete material for artificial reef and method for preparing the same

Abstract

This invention discloses a foamed concrete material for artificial reefs and its preparation method, belonging to the technical field of marine engineering building materials. It uses silicate cement, slag powder, fly ash, and metakaolin as the cementing system, compounded with a grafted dynamic alkalinity regulator, an amphiphilic polymerizable precursor, and ecologically cascaded inducing microcapsules. The precursor forms an organic-inorganic interpenetrating network in situ at the gas-liquid interface to reinforce the pore walls; the alkalinity regulator stabilizes the pore fluid pH for a long time through a two-site buffer; and the microcapsules achieve a gradual release of nutrients through a multi-level gated structure. This material exhibits a compressive strength of 5.4-5.8 MPa at high porosity, low water absorption, a stable pore fluid alkalinity reduction to the weakly alkaline range, slow nutrient release without sudden release, and high benthic diatom attachment. It combines good mechanical durability with ecological compatibility and can be used in marine ranching artificial reef engineering.

Description

Technical Field

[0001] This invention relates to the field of marine engineering building materials technology, and in particular to a foamed concrete material for artificial reefs and its preparation method. Background Technology

[0002] Artificial reefs are core facilities for restoring nearshore ecological environments and conserving fishery resources. Traditional cement-based artificial reef materials face multiple technical bottlenecks in actual marine service environments.

[0003] First, the hydration of silicate cement leads to extremely high alkalinity in the pore fluid, severely inhibiting the attachment and reproduction of benthic organisms. Existing technologies often reduce alkalinity by diluting the cement dosage with auxiliary cementitious materials such as slag or fly ash. However, these passive methods of reducing alkalinity have limited effectiveness, and unhydrated particles continue to release alkaline substances in the later stages, making it difficult to achieve dynamic stability of the pore fluid pH over a long service life.

[0004] Secondly, to create a habitat for organisms, artificial reef materials need to have high porosity. However, conventional physical foaming processes rely heavily on surfactants to stabilize the foam. These foam-stabilizing components are easily adsorbed or dissolved by the pore walls in the later stages of hydration, causing the pore walls to remain in a hydrophilic state for a long time, accelerating the erosion and softening of the porous pore walls by seawater. At the same time, the gas-liquid interface of the high-porosity matrix is ​​in a thermodynamically unstable state in the early stages of cement hydration, and bubbles are prone to coalescence or rupture, resulting in coarsening of the pore structure and an increase in pore wall defects. This makes it difficult to provide a stable and intact loading interface for functional components introduced later during the molding process.

[0005] Furthermore, to accelerate ecological succession, existing technologies attempt to introduce nutrients or attractants into the matrix. However, directly added active substances are easily lost rapidly in seawater; while when using conventional physical encapsulation of microcapsules, their single shell is prone to structural rupture under the chemical erosion of the highly alkaline pore liquid in concrete and the shear force of molding and stirring, resulting in the sudden release of internal substances in the early stages of sea entry, which cannot form a synergistic response that matches the reproductive cycle of marine organisms.

[0006] Therefore, it is urgent to simultaneously address the synergistic challenges of long-term control of pore liquid alkalinity, stability of pore wall microenvironment, and intelligent sustained release of active substances from the perspectives of material interface chemistry and structural design. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a foamed concrete material for artificial reefs and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A foamed concrete material for artificial reefs comprises the following components by weight: 30-45 parts silicate cement, 30-50 parts slag powder, 10-25 parts fly ash, 5-15 parts metakaolin, 0.5-3.0 parts amphiphilic polymerizable precursor, 5-12 parts grafted dynamic alkalinity regulator, 3-8 parts ecological cascade-inducing microcapsules, 0.2-0.6 parts polycarboxylate superplasticizer, 1.5-2.5 parts foaming agent, and water, added at a water-cement ratio of 0.30-0.35. The amphiphilic polymerizable precursor is a linear block copolymer containing perfluoropolyether segments, methacrylate end groups, and trialkoxysilane-terminated segments. The grafted dynamic alkalinity regulator is a grafted product in which the epoxy groups on the surface of fly ash microspheres and the phosphonic acid groups of aminotrimethylene phosphonic acid form COP bonds through ring opening. The ecological cascade attractant microcapsule has a core-shell structure. The core is a soluble nutrient core containing silicon, nitrogen, phosphorus and fish attractants. The inner layer is a gel layer formed by the hybridization of calcium alginate and chitin nanocrystals. The outer layer is a polyelectrolyte layer composed of alternating deposition of dopamine-modified chitosan and sodium alginate.

[0009] Preferably, the preparation method of the grafted dynamic alkalinity regulator includes the following steps: A1: Mix fly ash microspheres with 1.0-2.0 mol / L hydrochloric acid at a solid-liquid ratio of 1 g:(8-15) mL and stir at 60-75℃ for 2-3 h. After the reaction is complete, filter and wash with deionized water until the filtrate is neutral. Then, mix the acid-washed fly ash with 1.0-2.0 mol / L sodium hydroxide solution and stir under reflux at 80-90℃ for 4-6 h. After the reaction is complete, filter and wash with deionized water until the pH of the filtrate is neutral. Then, vacuum dry at 100-110℃ for 6-8 h to obtain hydroxyl-activated fly ash for later use. A2: Prepare a mixed solvent of anhydrous isopropanol and toluene with a volume ratio of 2-4:1, add γ-glycidyl etheroxypropyltrimethoxysilane, adjust the pH to 4.0-4.5 by adding glacial acetic acid dropwise, and pre-hydrolyze at 25-30℃ for 25-35 min; add the hydroxyl-activated fly ash prepared in step A1, heat to 80-85℃ under nitrogen protection, and reflux with mechanical stirring for 6-10 h; after cooling, filter, ultrasonically wash three times with anhydrous ethanol and acetone respectively, and vacuum dry at 80℃ to obtain epoxy-functionalized fly ash for later use; A3: Mix 50% aminotrimethylenephosphonic acid aqueous solution with anhydrous isopropanol at a volume ratio of 1:3, and azeotropically distill until no water droplets are observed in the water separator and the system is clear, to obtain anhydrous aminotrimethylenephosphonic acid isopropanol solution; add triethylamine at a molar ratio of 2.8-3.2 times that of aminotrimethylenephosphonic acid, and stir and activate at 75-80℃ for 30 min; then add epoxy-functionalized fly ash, and heat to 85-90℃ under nitrogen protection, and stir vigorously under reflux for 12-16 h; after cooling, wash twice with anhydrous ethanol, twice with a dilute ammonia-ethanol mixture with pH=10 and a volume ratio of 1:9, and wash with deionized water until neutral, and vacuum dry at 80℃ for 12 h to obtain grafted dynamic alkalinity regulator.

[0010] Preferably, in step A2, the amount of γ-glycidoxypropyltrimethoxysilane added is 10-20% of the mass of hydroxyl-activated fly ash.

[0011] Preferably, in step A3, the mass of aminotrimethylenephosphonic acid in the anhydrous aminotrimethylenephosphonic acid isopropanol solution accounts for 15-35% of the mass of epoxy-functionalized fly ash.

[0012] Through the above technical solution, fly ash microspheres, after acid washing and alkali activation, expose abundant silanols on their surface. The silanol generated from the hydrolysis of γ-glycidoxypropyltrimethoxysilane undergoes a condensation reaction with the silanols on the carrier surface, covalently anchoring the epoxy groups to the fly ash surface, thus preparing epoxy-functionalized fly ash. Aminotrimethylenephosphonic acid contains three phosphonic acid groups and is acidic. Upon addition of triethylamine, the triethylamine binds to the protons of the phosphonic acid groups, converting them into strongly nucleophilic phosphonate anions. These anions attack the less sterically hindered carbon atoms in the epoxy groups, undergoing ring-opening addition to form stable COP covalent bonds, thereby grafting aminotrimethylenephosphonic acid onto the fly ash surface and within the pores. After the reaction, the tertiary amine group at the center of the aminotrimethylenephosphonic acid remains in a free state.

[0013] During the cement hydration service stage, this grafted structure achieves dynamic alkalinity regulation through dual buffer sites. First, the residual weakly acidic phosphonate groups from the graft neutralize the hydroxide ions in the pore fluid, consuming excess alkalinity. The phosphonate ions generated subsequently combine with calcium ions to form slightly soluble complexes that adhere to the pore walls, preventing the loss of buffer components. Second, the free tertiary amine groups bind protons when the microenvironment pH tends to be neutral, preventing excessive pH decrease. These two mechanisms work synergistically to achieve long-term dynamic regulation of the alkalinity of the pore fluid in the artificial reef.

[0014] Preferably, the method for preparing the ecological cascade-inducing microcapsules includes the following steps: S1: Dissolve chitosan in a 1.0 wt% aqueous acetic acid solution to prepare a chitosan solution with a concentration of 1.5-2.5 wt%; add dopamine hydrochloride to the solution, with a molar ratio of dopamine to chitosan glycocycle units of 0.2-0.4:1; adjust the pH of the system to 5.5-6.0 with 1.0 mol / L NaOH solution, and stir the reaction at 40-50℃ in the dark for 12-18 h; after the reaction is completed, dialyze the product in deionized water for 48 h using a dialysis bag with a molecular weight cutoff of 8000-14000 Da, and finally freeze-dry to obtain dopamine-modified chitosan powder, which is then sealed for later use. S2: To achieve the target molar ratio of silicon, nitrogen, and phosphorus in the final microcapsule core of (6-8):(16-24):1, sodium silicate, sodium nitrate, and potassium dihydrogen phosphate are dissolved in deionized water, and 1.0-3.0% of fish attractant by weight of the core is added. The mixture is stirred at 60-70°C to form a clear mixed solution, with the solid content controlled at 15-25 wt%. The solution is then sent to a centrifugal spray dryer, and the resulting free-flowing powder with a particle size controlled at 10-30 μm is the nutrient core. S3: Disperse the nutrient core powder obtained in step S2 in an aqueous solution of sodium alginate with a concentration of 1.0-1.5 wt%, and add 5-15% (by weight of sodium alginate) of chitin nanocrystals. Use a homogenizer to disperse the mixture at 5000-8000 r / min for 10-15 min to obtain a uniform suspension. Use a peristaltic pump or syringe pump to dropwise add the suspension into a mixed coagulation bath containing 0.3-0.5 mol / L CaCl2 and 0.05-0.1 mol / L sodium citrate at a flow rate of 5-10 mL / min. After the addition is complete, allow the mixture to stand for cross-linking for 20-40 min, filter, and wash three times with deionized water to obtain monolayer core microcapsules. S4: Prepare two polyelectrolyte solutions: Solution A is prepared by dissolving the dopamine-modified chitosan powder synthesized in step S1 in 0.1 mol / L acetate-sodium acetate buffer solution at pH 5.0, with a concentration of 1.0-2.0 mg / mL; Solution B is prepared by dissolving sodium alginate in deionized water, with a concentration of 1.0-1.5 mg / mL; redisperse the monolayer core microcapsules obtained in step S3 in solution A, and slowly stir and adsorb at 100-200 r / min for 10-15 min. After filtration, use deionized water... Wash with water; then disperse the microcapsules in solution B, adsorb for 10-15 min under the same conditions, wash, and complete one double-layer deposition cycle, recorded as 1 BL; repeat the above alternating deposition operation for 4-8 BLs; immerse the self-assembled microcapsules in artificial seawater simulation solution at pH=8.2, stand at 25-30℃ for 2-4 h, during which air is introduced at a rate of 0.5-1.0 L / min for 30-60 min; after filtration, vacuum dry or freeze dry at ≤40℃ to obtain the finished product of ecological cascade induced microcapsules.

[0015] Preferably, in step S2, the fish attractant is selected from betaine, taurine, or a mixture thereof; the parameters of the centrifugal spray dryer are: inlet air temperature set at 180-210℃, outlet air temperature set at 80-95℃, feed rate set at 5-10mL / min, and atomization speed set at 15000-20000r / min.

[0016] Through the above technical solution, the ecological cascade induction microcapsule adopts a three-layer layer-by-layer construction strategy to achieve the synergistic functions of controlled slow release of nutrients, targeted induction of benthic diatoms, and active induction of fish.

[0017] The core is a nutrient core prepared by spray drying, which is composed of sodium silicate, sodium nitrate and potassium dihydrogen phosphate in the optimal Si:N:P molar ratio for the growth of benthic diatoms, and is compounded with fish attractants (betaine or taurine) to provide directional chemical signals for subsequent biological reproduction.

[0018] The inner gel is formed by sodium alginate in a sodium citrate-containing Ca2+. 2+ In the coagulation bath, a calcium alginate network is formed through calcium ion cross-linking, and chitin nanocrystals are uniformly incorporated. The citrate system regulates the initial network structure and pore distribution through coordination and ionic strength effects, synergistically suppressing burst release in the outer layer during the initial stage of service. As benthic diatoms colonize and grow vigorously on the reef surface, their secreted chitinases specifically degrade the chitin nanocrystals in the inner layer, leading to a gradual increase in the porosity and diffusion channels of the calcium alginate gel network, thereby triggering a feedback release of nutrients.

[0019] The outer shell is a polyelectrolyte multilayer membrane formed by the alternating deposition of dopamine-modified chitosan and sodium alginate through electrostatic self-assembly. This outer layer is assembled in an acidic buffer solution at pH 5.0, and then immersed in artificial seawater at pH 8.2. Under weakly alkaline conditions, the dopamine phenolic hydroxyl groups are oxidized by air, undergoing self-polymerization and cross-linking to form a stable polydopamine network. This network locks the multilayer membrane in place, significantly enhancing the mechanical strength of the inner gel layer and preventing the sudden release of nutrients during casting and the initial stages of service. Appropriate control of the cross-linking density imparts suitable semi-permeability to the outer layer, maintaining its initial barrier function while preserving the accessibility of enzyme molecules and the pathway for nutrient diffusion.

[0020] The three-layered structure forms a multi-level gating system of physical shielding, biological enzymatic cleavage, and chemical response, creating a positive feedback coupling between the nutrient release rate and the reproductive and metabolic rate of benthic diatoms. When diatoms grow vigorously, enzyme secretion increases, inner layer degradation accelerates, and nutrient release increases; when diatom growth is restricted, enzyme secretion decreases, inner layer degradation slows down, and release decreases accordingly, achieving synchronous matching between nutrient supply and ecosystem succession.

[0021] Preferably, the preparation steps of the amphiphilic polymerizable precursor are as follows: Dry perfluoropolyether diols with a number-average molecular weight of 1000-2000 are mixed with isophorone diisocyanate at a molar ratio of 1:1.02-1.08. Dibutyltin dilaurate is added, and the mixture is reacted at 60-75°C under nitrogen protection for 1.5-3 hours. The temperature is then lowered to 50-65°C, and hydroxyethyl methacrylate and hydroquinone (polymerization inhibitor) in equimolar amounts with residual -NCO are added. The reaction is continued for 1.5-3 hours until -NCO ≤ 0.1%. Isophorone is then added as needed. Ketone diisocyanate was added to make the amount of -NCO in the system 0.05-0.15 times that of the perfluoropolyether diol. The reaction was continued at 50-60℃ for 0.5-1h, followed by heating to 60-70℃. 3-Aminopropyltriethoxysilane with a molar ratio of 1:1-1.05 to -NCO was added dropwise, and the reaction was continued for 1-2h until -NCO completely disappeared, yielding the target amphiphilic polymerizable precursor with a moisture content below 200ppm throughout the process. Methacrylate polymerizable end groups and triethoxysilane hydrolytic condensation end groups were introduced at both ends of the perfluoropolyether segments. The perfluoropolyether segments provided extremely low surface energy and strong hydrophobic properties, driving the spontaneous accumulation of molecules at the gas-liquid interface in the cement paste. The methacrylate end groups underwent free radical polymerization under the action of an initiator, forming an organic polymer network. The triethoxysilane end groups hydrolyzed and condensed in the alkaline cement pore liquid, chemically bonding with inorganic hydration products. The three work together to construct an organic-inorganic interpenetrating network at the bubble interface.

[0022] After the precursor is incorporated into the cement paste, the perfluoropolyether segments drive the molecules to migrate towards the gas-liquid interface and align in a specific direction. The methacrylate end groups undergo free radical polymerization under the action of a redox initiation system, crosslinking to form a film at the interface; the triethoxysilane end groups hydrolyze in an alkaline environment to generate silanols, which then condense with the silanols on the pore wall surface, forming a covalent anchor. The synergistic effect of these three actions forms a composite armor around the bubbles that combines flexibility (organic film) and rigidity (inorganic condensation network), enhancing the crack resistance of the pore walls and the stability of the interface.

[0023] A method for preparing foamed concrete material for artificial reefs includes the following steps: (1) Weigh silicate cement, slag powder, fly ash, metakaolin and grafted dynamic alkalinity regulator according to the proportion, put them into the mixer and dry mix for 2-5 minutes to obtain premixed powder; (2) Disperse the amphiphilic polymerizable precursor and polycarboxylate superplasticizer in water and stir at low speed until uniform to obtain a mixture; (3) Add the premixed powder from step (1) to the mixture from step (2), first stir slowly at 100-200 r / min for 1-2 min, then stir rapidly at 400-600 r / min for 2-3 min to form a uniform slurry; (4) Add the ecological cascade inducing microcapsules to the slurry from step (3) and stir at a low speed of 50-100 rpm for 1-2 minutes until the microcapsules are evenly dispersed. (5) Add foaming agent, stir at 200-400 rpm for 15-30 seconds and quickly pour into the mold, cover with film and let stand for 24-48 hours for initial curing, demold and steam curing: temperature 38-42℃, relative humidity ≥95%, curing for 48 hours; then immerse the test block in natural or artificial seawater and continue curing at 20-25℃ for 7 days to obtain the finished product.

[0024] Preferably, in step (2), a redox initiator is added to the water. The redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a 1:1 molar ratio, and the amount is 0.1-0.5% of the molar number of the amphiphilic polymerizable precursor.

[0025] Through the above technical solutions, this invention constructs a novel artificial reef material system integrating "interface enhancement, dynamic alkalinity reduction, and intelligent attraction." First, the amphiphilic polymerizable precursor constructs a "composite armor" at the gas-liquid interface, interwoven with a flexible organic membrane and a rigid inorganic condensation network, fundamentally solving the problem of easy softening and rapid strength loss of high-porosity concrete pore walls. Second, the grafted dynamic alkalinity regulator utilizes the synergistic effect of the dual buffer sites of phosphonic acid groups and free tertiary amines to achieve a smooth transition and long-term stability of pore fluid alkalinity from high alkalinity to a weakly alkaline environment suitable for marine organism growth, breaking through the bottleneck of limited alkalinity reduction and easy reversion to alkalinity in traditional materials. Finally, the ecological cascade attraction microcapsules utilize a multi-level gating mechanism of physical shielding, biological enzymatic cleavage, and chemical cross-linking to form a positive feedback coupling between the nutrient release rate and the reproductive metabolism of benthic diatoms. Combined with the active feeding signal from the core, this achieves a leap from "passively waiting for biological attachment" to "actively inducing ecological aggregation" in the artificial reef. This invention achieves a high degree of synergy between material mechanical durability, pore fluid microenvironment and marine ecological succession at the molecular chemical level, providing a high-performance ecological substrate for the construction of modern marine ranches.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs an amphiphilic polymerizable precursor that spontaneously accumulates at the gas-liquid interface in cement paste. Through free radical polymerization of methacrylate end groups and hydrolytic condensation of triethoxysilane end groups, an organic-inorganic interpenetrating network is formed in situ around the bubbles. This network combines the toughness of a flexible organic membrane with the interfacial anchoring effect of a rigid siloxane network, enabling foamed concrete to maintain high compressive strength under high porosity conditions while significantly reducing water absorption, effectively alleviating the contradiction between high porosity and low mechanical strength.

[0027] 2. This invention employs a grafted dynamic alkalinity regulator, grafting aminotrimethylene phosphonic acid onto the surface of fly ash microspheres via COP covalent bonds. The residual phosphonic acid groups neutralize hydroxide ions in the pore solution, consuming excess alkalinity. The ionized phosphonate ions form slightly soluble complexes with calcium ions, adhering to the pore walls. Simultaneously, free tertiary amine groups bind protons when the microenvironment pH is low. This dual-buffer site synergistic mechanism allows the pore solution pH to steadily decrease from high alkalinity to a weakly alkaline range during the service life, unlike ordinary fly ash which only passively reduces alkalinity and results in a persistently high pH. This achieves long-term dynamic and stable regulation of pore solution alkalinity.

[0028] 3. This invention employs a multi-level gated structure of ecologically cascaded inducing microcapsules. The core provides nutrients in a suitable ratio of silicon, nitrogen, and phosphorus, as well as fish attractants. The inner layer, a hybrid gel of calcium alginate and chitin nanocrystals, can be specifically degraded by chitinase secreted by benthic diatoms. The outer layer, dopamine-modified chitosan and sodium alginate, is locked in place through alternating deposition and oxidative cross-linking with weakly alkaline seawater. This structure results in a gradual, sustained release of nutrients, avoiding the initial burst release phenomenon found in ordinary single-shell microcapsules. Combined with alkalinity regulation, the attachment of benthic diatoms is significantly increased, achieving synchronous matching between nutrient supply and marine ecological succession.

[0029] 4. This invention synergistically combines the above three functional components into a foamed concrete system. The amphiphilic polymerizable precursor ensures structural strength and pore wall stability under high porosity; the grafted dynamic alkalinity regulator creates a weakly alkaline microenvironment suitable for bioattachment; and the ecological cascade induction microcapsules provide nutrient slow-release and ecological induction signals that match the diatom reproduction cycle. These three components work synergistically from three levels: mechanical support, interfacial chemical regulation, and ecological function adaptation, effectively solving the technical bottlenecks of excessively high alkalinity, insufficient mechanical durability, and weak ecological function in traditional artificial reef materials. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] Example 1: I. Preparation of Grafted Dynamic Alkalinity Regulator A1: Weigh 100g of fly ash microspheres, add 800mL of 1.0mol / L hydrochloric acid, stir at 60℃ for 2h; filter and wash with water until neutral. Then add 800mL of 1.0mol / L sodium hydroxide solution, reflux at 80℃ for 4h; filter and wash with water until neutral, vacuum dry at 100℃ for 6h to obtain hydroxyl-activated fly ash; A2: Prepare 600 mL of anhydrous isopropanol:toluene = 2:1 mixture; add 10 g of γ-glycidyl etheroxypropyltrimethoxysilane (10% of the mass of hydroxyl-activated fly ash); adjust pH to 4.0 with glacial acetic acid, pre-hydrolyze at 25℃ for 25 min; add the above hydroxyl-activated fly ash, reflux at 80℃ for 6 h under nitrogen protection; ultrasonically wash 3 times each with ethanol and acetone, and vacuum dry at 80℃ to obtain epoxy-functionalized fly ash. A3: Take 100 mL of 50% aminotrimethylenephosphonic acid aqueous solution and 300 mL of anhydrous isopropanol, azeotropically remove water, and the effective pure aminotrimethylenephosphonic acid participating in the reaction in the system is 15 g; add triethylamine (2.8 times the molar amount of aminotrimethylenephosphonic acid), activate at 75℃ for 30 min; add 100 g of epoxy-functionalized fly ash, reflux at 85℃ for 12 h under nitrogen protection; wash successively with ethanol, dilute ammonia-ethanol, and deionized water until neutral, and vacuum dry at 80℃ for 12 h to obtain the grafted dynamic alkalinity regulator.

[0032] II. Preparation of Eco-Cascade Induced Microcapsules S1: Take 15g of chitosan (degree of deacetylation ≥85%, viscosity 100mPa·s), dissolve it in 1000mL of 1.0wt% acetic acid aqueous solution to prepare a 1.5wt% solution; add dopamine hydrochloride (molar ratio of dopamine to chitosan glycocycle unit = 0.2:1); adjust pH to 5.5 with NaOH, stir at 40℃ in the dark for 12h; dialyze through an 8000Da dialysis bag for 48h, freeze dry to obtain dopamine-modified chitosan; S2: Weigh 54g of sodium silicate, 100g of sodium nitrate, and 10g of potassium dihydrogen phosphate according to Si:N:P=6:16:1, dissolve them in deionized water to prepare a solution with a solid content of 15wt%; add 1.0g of betaine (1.0% of the total mass of the core), stir and clarify at 60℃; centrifuge and spray dry: inlet air 180℃, outlet air 80℃, feed 5mL / min, atomization 15000r / min to obtain nutrient cores (particle size 10μm). S3: Disperse 50g of nutrient cores in 500mL of 1.0wt% sodium alginate aqueous solution, add 0.25g of chitin nanocrystals (5% sodium alginate by mass), disperse at 5000r / min for 10min; add dropwise 0.3mol / L CaCl2 and 0.05mol / L sodium citrate coagulation bath at 5mL / min, crosslink for 20min; filter and wash 3 times with water to obtain monolayer core microcapsules; S4: Solution A: 1.0 mg / mL dopamine-modified chitosan (pH 5.0 acetate-sodium acetate buffer); Solution B: 1.0 mg / mL sodium alginate; Microcapsules were adsorbed in A and B for 10 min each, and circulated 4 BL; Immersed in artificial seawater at pH 8.2, stood at 25℃ for 2 h, and oxidized in air at 0.5 L / min for 30 min; Vacuum dried at ≤40℃ to obtain ecological cascade inducing microcapsules.

[0033] III. Preparation of Amphiphilic Polymerizable Precursors Weigh 100g of perfluoropolyether diol (Mn=1000) and add it to isophorone diisocyanate at a molar ratio of 1:1.02; add 0.1g of dibutyltin dilaurate and react at 60℃ under nitrogen protection for 1.5h; cool to 50℃, add hydroxyethyl methacrylate (equimolar with residual -NCO) and 0.05g of hydroquinone, and react for 1.5h until -NCO≤0.1%; add isophorone diisocyanate to make the -NCO in the system 0.05 times the amount of perfluoropolyether diol, and react at 50℃ for 0.5h; heat to 60℃, add 3-aminopropyltriethoxysilane (molar ratio with -NCO 1:1), and react for 1h until -NCO completely disappears, with a total moisture content <200ppm, to obtain an amphiphilic polymerizable precursor.

[0034] IV. Preparation of Foamed Concrete for Artificial Reefs (1) Weigh out: 300g of silicate cement, 300g of slag powder, 100g of fly ash, 50g of metakaolin, and 50g of grafted dynamic alkalinity regulator. Dry mix for 2 minutes to obtain premixed powder. (2) Take 5g of amphiphilic polymerizable precursor and 2g of polycarboxylate superplasticizer, add 241.5g of water (water-to-gel ratio 0.30); add redox initiator (ammonium persulfate: sodium bisulfite = 1:1), the amount of which is 0.1% of the number of moles of the precursor, and stir evenly; (3) Add the powder to the liquid, stir at 100 r / min for 1 min, then stir at 400 r / min for 2 min to form a uniform slurry; (4) Add 30g of ecological cascade induction microcapsules and stir at 50rpm for 1min until evenly dispersed; (5) Add 15g of plant protein foaming agent, stir at 200rpm for 15s, and pour quickly; cover with film and let stand for 24h, then steam at 38℃ and humidity ≥95% for 48h after demolding; then cure in seawater at 20℃ for 7 days to obtain the finished product.

[0035] Example 2: I. Preparation of Grafted Dynamic Alkalinity Regulator A1: Weigh 100g of fly ash microspheres, add 1150mL of 1.5mol / L hydrochloric acid, stir at 67.5℃ for 2.5h; filter and wash with water until neutral. Then add 1000mL of 1.5mol / L sodium hydroxide solution, reflux at 85℃ for 5h; filter and wash with water until neutral, vacuum dry at 105℃ for 7h to obtain hydroxyl-activated fly ash; A2: Prepare 800 mL of anhydrous isopropanol:toluene = 3:1 mixture; add 15 g of γ-glycidyl etheroxypropyltrimethoxysilane (15% of the mass of hydroxyl-activated fly ash); adjust pH to 4.25 with glacial acetic acid, pre-hydrolyze at 27.5℃ for 30 min; add the above hydroxyl-activated fly ash, reflux at 82.5℃ for 8 h under nitrogen protection; ultrasonically wash 3 times each with ethanol and acetone, and vacuum dry at 80℃ to obtain epoxy-functionalized fly ash; A3: Take 150 mL of 50% aminotrimethylenephosphonic acid aqueous solution and 450 mL of anhydrous isopropanol, azeotropically remove water, and the effective pure aminotrimethylenephosphonic acid participating in the reaction in the system is 25 g; add triethylamine (3.0 times the molar amount of aminotrimethylenephosphonic acid), activate at 77.5℃ for 30 min; add 100 g of epoxy-functionalized fly ash, reflux at 87.5℃ for 14 h under nitrogen protection; wash successively with ethanol, dilute ammonia-ethanol, and deionized water until neutral, and vacuum dry at 80℃ for 12 h to obtain the grafted dynamic alkalinity regulator.

[0036] II. Preparation of Eco-Cascade Induced Microcapsules S1: Take 20g of chitosan (degree of deacetylation ≥85%, viscosity 150mPa·s), dissolve it in 1000mL of 1.0wt% acetic acid aqueous solution to prepare a 2.0wt% solution; add dopamine hydrochloride (molar ratio of dopamine to chitosan glycocycle unit = 0.3:1); adjust pH to 5.75 with NaOH, stir at 45℃ in the dark for 15h; dialyze through a 11000Da dialysis bag for 48h, freeze dry to obtain dopamine-modified chitosan; S2: Weigh 63g of sodium silicate, 125g of sodium nitrate, and 10g of potassium dihydrogen phosphate according to Si:N:P=7:20:1, dissolve them in deionized water to prepare a solution with a solid content of 20wt%; add 2.0g of taurine (total mass of the core is 2.0%), stir and clarify at 65℃; centrifuge and spray dry: inlet air 195℃, outlet air 87.5℃, feed 7.5mL / min, atomization 17500r / min to obtain nutrient cores (particle size 20μm); S3: Disperse 60g of nutrient cores in 500mL of 1.25wt% sodium alginate aqueous solution, add 0.625g of chitin nanocrystals (10% of sodium alginate mass), and disperse at 6500r / min for 12.5min; add 0.4mol / L CaCl2 and 0.075mol / L sodium citrate coagulation bath dropwise at 7.5mL / min, and crosslink for 30min; filter and wash with water 3 times to obtain monolayer core microcapsules; S4: Solution A: 1.5 mg / mL dopamine-modified chitosan (pH 5.0 acetate-sodium acetate buffer); Solution B: 1.25 mg / mL sodium alginate; Microcapsules were adsorbed in A and B for 12.5 min each, followed by 6 BL cycles; Immersed in artificial seawater at pH 8.2, allowed to stand at 27.5℃ for 3 h, and oxidized in air at 0.75 L / min for 45 min; Freeze-dried at ≤40℃ to obtain eco-cascade-inducing microcapsules.

[0037] III. Preparation of Amphiphilic Polymerizable Precursors Weigh 100g of perfluoropolyether diol (Mn=1500) and add it to isophorone diisocyanate at a molar ratio of 1:1.05; add 0.12g of dibutyltin dilaurate and react at 67.5℃ under nitrogen protection for 2.25h; cool to 57.5℃, add hydroxyethyl methacrylate (equimolar with residual -NCO) and 0.06g of hydroquinone, and react for 2.25h until -NCO≤0.1%; add isophorone diisocyanate to make the -NCO in the system 0.10 times the amount of perfluoropolyether diol, and react at 55℃ for 0.75h; heat to 65℃, add 3-aminopropyltriethoxysilane (molar ratio with -NCO 1:1.025), and react for 1.5h until -NCO completely disappears, with a total moisture content <200ppm, to obtain an amphiphilic polymerizable precursor.

[0038] IV. Preparation of Foamed Concrete for Artificial Reefs (1) Weigh out: 375g of silicate cement, 400g of slag powder, 175g of fly ash, 100g of metakaolin, and 85g of grafted dynamic alkalinity regulator. Dry mix for 3.5min to obtain premixed powder. (2) Take 17.5g of amphiphilic polymerizable precursor and 4g of polycarboxylate superplasticizer, add 341.25g of water (water-to-gel ratio 0.325); add redox initiator (ammonium persulfate: sodium bisulfite = 1:1), the amount of which is 0.3% of the precursor molars, and stir evenly; (3) Add the powder to the liquid, stir at 150 r / min for 1.5 min, then stir at 500 r / min for 2.5 min to form a uniform slurry; (4) Add 55g of ecological cascade induction microcapsules and stir at 75rpm for 1.5min until evenly dispersed; (5) Add 20g of plant protein foaming agent, stir at 300rpm for 22.5s, and pour quickly; cover with film and let stand for 36h, then steam at 40℃ and humidity ≥95% for 48h after demolding; then cure in seawater at 22.5℃ for 7 days to obtain the finished product.

[0039] Example 3: I. Preparation of Grafted Dynamic Alkalinity Regulator A1: Weigh 100g of fly ash microspheres, add 1500mL of 2.0mol / L hydrochloric acid, stir at 75℃ for 3h; filter and wash with water until neutral. Then add 1200mL of 2.0mol / L sodium hydroxide solution, reflux at 90℃ for 6h; filter and wash with water until neutral, vacuum dry at 110℃ for 8h to obtain hydroxyl-activated fly ash; A2: Prepare 1000 mL of anhydrous isopropanol:toluene = 4:1 mixture; add 20 g of γ-glycidyl etheroxypropyltrimethoxysilane (20% of the mass of hydroxyl-activated fly ash); adjust pH to 4.5 with glacial acetic acid, pre-hydrolyze at 30℃ for 35 min; add the above hydroxyl-activated fly ash, reflux at 85℃ for 10 h under nitrogen protection; ultrasonically wash three times each with ethanol and acetone, and vacuum dry at 80℃ to obtain epoxy-functionalized fly ash. A3: Take 200 mL of 50% aminotrimethylenephosphonic acid aqueous solution and 600 mL of anhydrous isopropanol. The effective pure aminotrimethylenephosphonic acid participating in the reaction in the azeotropic dehydration system is 35 g. Add triethylamine (3.2 times the molar amount of aminotrimethylenephosphonic acid) and activate at 80 °C for 30 min. Add 100 g of epoxy-functionalized fly ash and reflux at 90 °C for 16 h under nitrogen protection. Wash successively with ethanol, dilute ammonia-ethanol and deionized water until neutral, and vacuum dry at 80 °C for 12 h to obtain the grafted dynamic alkalinity regulator.

[0040] II. Preparation of Eco-Cascade Induced Microcapsules S1: Take 25g of chitosan (degree of deacetylation ≥85%, viscosity 200mPa·s), dissolve it in 1000mL of 1.0wt% acetic acid aqueous solution to prepare a 2.5wt% solution; add dopamine hydrochloride (molar ratio of dopamine to chitosan glycocycle unit = 0.4:1); adjust pH to 6.0 with NaOH, stir at 50℃ in the dark for 18h; dialyze through a 14000Da dialysis bag for 48h, freeze dry to obtain dopamine-modified chitosan; S2: Weigh 72g of sodium silicate, 150g of sodium nitrate, and 10g of potassium dihydrogen phosphate according to Si:N:P=8:24:1, dissolve them in deionized water to prepare a solution with a solid content of 25wt%; add 3.0g of a mixture of betaine and taurine (total mass of the core 3.0%), stir and clarify at 70℃; centrifuge and spray dry: inlet air 210℃, outlet air 95℃, feed 10mL / min, atomization 20000r / min to obtain nutrient cores (particle size 30μm). S3: Disperse 70g of nutrient cores in 500mL of 1.5wt% sodium alginate aqueous solution, add 1.125g of chitin nanocrystals (15% of sodium alginate mass), disperse at 8000r / min for 15min; add dropwise 0.5mol / L CaCl2 and 0.1mol / L sodium citrate coagulation bath at 10mL / min, crosslink for 40min; filter and wash 3 times with water to obtain monolayer core microcapsules; S4: Solution A: 2.0 mg / mL dopamine-modified chitosan (pH 5.0 acetate-sodium acetate buffer); Solution B: 1.5 mg / mL sodium alginate; Microcapsules were adsorbed in A and B for 15 min each, and circulated 8 BL; Immersed in artificial seawater at pH 8.2, stood at 30℃ for 4 h, and oxidized in air at 1.0 L / min for 60 min; Vacuum dried at ≤40℃ to obtain ecological cascade inducing microcapsules.

[0041] III. Preparation of Amphiphilic Polymerizable Precursors Weigh 100g of perfluoropolyether diol (Mn=2000) and add it to isophorone diisocyanate at a molar ratio of 1:1.08; add 0.15g of dibutyltin dilaurate and react at 75℃ under nitrogen protection for 3h; cool to 65℃, add hydroxyethyl methacrylate (equimolar with residual -NCO) and 0.08g of hydroquinone, and react for 3h until -NCO≤0.1%; add isophorone diisocyanate to make the -NCO in the system 0.15 times the amount of perfluoropolyether diol, and react at 60℃ for 1h; heat to 70℃, add 3-aminopropyltriethoxysilane (molar ratio with -NCO 1:1.05), and react for 2h until -NCO completely disappears, with a total moisture content <200ppm, to obtain an amphiphilic polymerizable precursor.

[0042] IV. Preparation of Foamed Concrete for Artificial Reefs (1) Weigh out: 450g of silicate cement, 500g of slag powder, 250g of fly ash, 150g of metakaolin, and 120g of grafted dynamic alkalinity regulator. Dry mix for 5 minutes to obtain premixed powder. (2) Take 30g of amphiphilic polymerizable precursor and 6g of polycarboxylate superplasticizer, add 441g of water (water-to-gel ratio 0.35); add redox initiator (ammonium persulfate: sodium bisulfite = 1:1), the amount of which is 0.5% of the molar amount of the precursor, and stir evenly; (3) Add the powder to the liquid, stir at 200 r / min for 2 min, then stir at 600 r / min for 3 min to form a uniform slurry; (4) Add 80g of ecological cascade induction microcapsules and stir at 100rpm for 2min until evenly dispersed; (5) Add 25g of plant protein foaming agent, stir at 400rpm for 30s, and pour quickly; cover with film and let stand for 48h, then steam at 42℃ and humidity ≥95% for 48h after demolding; then cure in seawater at 25℃ for 7 days to obtain the finished product.

[0043] Comparative Example 1: Based on Example 2, the difference is that no grafted dynamic alkalinity regulator, amphiphilic polymerizable precursor and eco-cascade inducing microcapsules were added, and no substitutes were added. The rest is the same as Example 2.

[0044] Comparative Example 2: Based on Example 2, the difference is that no grafted dynamic alkalinity regulator is added, and no substitutes are added. Otherwise, it is the same as Example 2.

[0045] Comparative Example 3: Based on Example 2, the difference is that no amphiphilic polymerizable precursor is added, and the rest is the same as Example 2.

[0046] Comparative Example 4: Based on Example 2, the difference is that pure calcium alginate blank microspheres without nutrient cores of equal mass are used instead of ecological cascade inducing microcapsules, and the rest is the same as in Example 2.

[0047] Comparative Example 5: Based on Example 2, the difference is that: ordinary single-shell calcium alginate microcapsules of equal mass are used instead of ecological cascade inducing microcapsules; the nutrient salt composition of the core of ordinary microcapsules is the same as in Example 2, but without the chitin nanofiber inner layer and the dopamine-modified chitosan outer layer, the rest is the same as in Example 2.

[0048] Comparative Example 6: Based on Example 2, the difference is that an equal mass of unmodified ordinary fly ash microspheres is used instead of the grafted dynamic alkalinity regulator, and the rest is the same as Example 2.

[0049] Comparative Example 7: Based on Example 2, the difference is that an equal mass of conventional polyoxyethylene ether foam stabilizer is used instead of the amphiphilic polymerizable precursor, and the rest is the same as Example 2.

[0050] Performance testing: The grafted dynamic alkalinity regulator, ecological cascade inducing microcapsules, and artificial reef foam concrete prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to the following tests, and the test methods are as follows: 1. Dry apparent density and compressive strength test: The specimens from each embodiment and comparative example were cut into standard cubes of 100mm × 100mm × 100mm. The specimens were dried at 60℃ to constant weight, and their mass was measured using an electronic balance to calculate the dry apparent density. Considering the toughness characteristics of the foamed concrete matrix, the specimens were placed on a universal testing machine and subjected to a constant loading rate of (0.6 ± 0.1) kN / s to test their compressive strength. Six parallel specimens were prepared for each group, and the arithmetic mean was used as the final result.

[0051] 2. Water absorption rate test: Referring to the test operation procedures of GB / T 11969-2020, in order to match the actual marine service environment of artificial reefs, the soaking medium was replaced with artificial seawater simulation solution instead of pure water. The initial mass m0 of a 100mm cube specimen dried to constant weight was weighed and completely immersed in artificial seawater simulation solution at (20±2)℃ and pH=8.2, with the liquid level above the top surface of the specimen by more than 30mm. After soaking for 48h, the specimen was removed, the surface free water was wiped off with a wrung-out damp towel, and the mass m1 after water absorption was quickly weighed. The water absorption rate was calculated according to formula (1), and the average value of 6 parallel samples in each group was used to evaluate the pore wall compactness and seawater permeability. Water absorption rate (%) = [(m1-m0) / m0]×100%, formula (1).

[0052] 3. Dynamic extraction of alkalinity and pH testing of pore fluid: The pore fluid was extracted using anhydrous isopropanol displacement. At 7, 14, 28, 56, and 90 days of age, the specimens were broken up, and small, defect-free pieces were quickly immersed in sufficient anhydrous isopropanol. The pieces were then sealed and allowed to stand for at least 24 hours to terminate hydration and displace the pore fluid. The resulting clear filtrate was obtained by vacuum filtration, and the pH was measured using a calibrated precision pH meter in a constant temperature water bath at (25±1)℃. At least three parallel samples were prepared for each age, and pH versus age curves were plotted.

[0053] 4. Nutrient salt cumulative release rate test: The in vitro nutrient release performance was tested using a dynamic oscillation dissolution method. Crushed test blocks containing equal amounts of microcapsules from each example and comparative example were immersed in 500 mL of simulated artificial seawater at pH 8.2 and placed in a constant-temperature shaking incubator at (25±1)℃ with shaking at (120±10) r / min. Samples of 5 mL were taken at 1, 3, 7, 14, 28, 56, and 90 days, and an equal volume of isothermal fresh artificial seawater was added simultaneously. The phosphate ion concentration was determined using the ammonium molybdate spectrophotometric method according to the marine monitoring standard GB / T 12763.4-2007. The cumulative nutrient release rate was calculated, release curves were plotted, and kinetic fitting was performed to evaluate the anti-burst release performance and enzyme response feedback sustained-release characteristics of the microcapsules.

[0054] 5. Benthic diatom attachment biomass test: Referring to the marine survey standard GB / T 12763.6-2007, each test block was cut into standard 50mm×50mm×10mm pieces, fixed in a floating raft in the actual sea area or an indoor simulated incubator, inoculated with target benthic diatoms, and continuously cultured for 30 days (no less than 60 days for cross-seasonal experiments). After the culture was completed, the pieces were removed, and the attached organisms were washed off to the filter membrane with a soft brush. Chlorophyll a was extracted for 24 hours with 90% acetone solution at 4℃ in the dark. After centrifugation of the extract, the supernatant was collected, and the absorbance at wavelengths of 750nm, 664nm, 647nm, and 630nm was measured using a spectrophotometer. The chlorophyll a concentration was calculated by substituting the values ​​into the Jeffrey-Humphrey formula to quantitatively characterize the colonization and reproduction level of benthic diatoms. Using the chlorophyll a concentration of Example 2 as a benchmark, the relative attachment rate was calculated by dividing the chlorophyll a concentration of each sample by the chlorophyll a concentration of Example 2 and then multiplying by 100%.

[0055] The results are as follows: Table 1. Test results for examples and comparative examples.

[0056] Data analysis: The foamed concrete materials for artificial reefs prepared in Examples 1-3 have a dry apparent density of 705-735 kg / m³. 3 Under conditions of 64.5-65.2% porosity, the 28-day compressive strength reached 5.4-5.8 MPa, significantly higher than that of ordinary foamed concrete. Its 48-hour water absorption rate was controlled between 30.8-33.6%, indicating dense pore walls and strong resistance to seawater permeation. The pH value of the pore liquid gradually decreased from 10.0-10.2 at 7 days of curing to 8.6-8.8 at 90 days, achieving a smooth transition from a highly alkaline to a weakly alkaline environment. The cumulative release of nutrients exhibited a gentle S-shaped curve, with a release rate of 10.8-13.1% at 1 day and approximately 83.2-86.8% at 90 days, demonstrating good anti-burst and slow-release performance. The amount of benthic diatoms attached reached 25.4-30.3 μg / cm³. 2 The relative adhesion rate of chlorophyll a exceeded 80%, indicating that the material can effectively induce benthic diatom colonization and promote ecological succession.

[0057] Comparative Example 1, lacking the grafted dynamic alkalinity regulator, amphiphilic polymerizable precursor, and eco-cascade inducing microcapsules, exhibited a compressive strength of only 1.8 MPa, a water absorption rate as high as 58.5%, a pore slurry pH maintained at 12.1 after 90 days, and a chlorophyll a concentration of only 3.2 μg / cm³. 2 This demonstrates that the three functional components together determine the material's mechanical properties, alkalinity regulation effect, and ecological function.

[0058] Comparative Example 2, lacking only the grafted dynamic alkalinity regulator, had a compressive strength similar to Comparative Example 1 at 1.7 MPa, a water absorption rate of 59.2%, and a pH that dropped to 11.2 after 90 days. Although slightly lower than Comparative Example 1, it was still in the high-alkalinity range, and its chlorophyll a concentration was only 4.1 μg / cm³. 2 This demonstrates that the long-term buffering effect of grafted dynamic alkalinity regulators on pore fluid alkalinity is irreplaceable. Without them, the alkalinity cannot be reduced to the weakly alkaline range, thus severely inhibiting the attachment of benthic diatoms.

[0059] Comparative Example 3, without the addition of the amphiphilic polymerizable precursor, showed a 28-day compressive strength decreasing to 2.4 MPa and a water absorption rate increasing to 49.6%, but the chlorophyll a concentration still reached 12.0 μg / cm³. 2 The strength decreased, but bioattachment remained acceptable, indicating that the amphiphilic polymerizable precursor is key to improving the mechanical properties of the pore walls. The presence of alkalinity regulators and microcapsules still supports diatom growth, further confirming the decisive role of alkalinity and nutrient supply in ecological induction.

[0060] Comparative Example 4 used pure calcium alginate blank microspheres without nutrient cores to replace the ecological cascade induction microcapsules. Its compressive strength was 3.9 MPa, water absorption rate was 31.5%, and pore liquid pH was similar to the example, but the chlorophyll a concentration was only 2.5 μg / cm³. 2 This indicates that the nutrient nucleus in the microcapsule is the material basis for diatom reproduction, and ecological induction cannot be achieved even with suitable alkalinity if nutrients are lacking.

[0061] Comparative Example 5 used ordinary single-shell calcium alginate microcapsules instead of the ecological cascade inducing microcapsules. Its nutrient release rate reached 58.7% after 1 day and 74.5% after 3 days, exhibiting typical burst release characteristics, with a cumulative release rate of 97.5% over 90 days. The chlorophyll a concentration was only 12.4 μg / cm³. 2 The results are significantly lower than in the previous embodiment. This demonstrates the unique advantages of multi-level gating structures in suppressing burst release and achieving feedback-based sustained release, which ordinary microcapsules cannot synchronize with the diatom reproduction cycle.

[0062] Comparative Example 6 used unmodified ordinary fly ash microspheres instead of the grafted dynamic alkalinity regulator. Its compressive strength still reached 5.5 MPa, and its water absorption rate was 31.2%, similar to the example. However, the pore liquid pH slowly decreased from 12.4 at 7 days to 11.6 at 90 days, remaining consistently above 11, and the chlorophyll a concentration was only 4.5 μg / cm³. 2 This indicates that ordinary fly ash only has the functions of physical filling and passive alkali reduction. Grafting modification and dual-site buffering are necessary conditions for achieving long-term dynamic alkali control, and a high-alkali environment continuously inhibits bioattachment.

[0063] Comparative Example 7 used a conventional polyoxyethylene ether-based foam stabilizer instead of the amphiphilic polymerizable precursor. Its compressive strength decreased to 2.5 MPa, and its water absorption increased to 51.3%, but the pore liquid pH was close to that of the example, and the chlorophyll a concentration reached 13.2 μg / cm³. 2 It was confirmed that conventional foam stabilizers can only temporarily stabilize foam and cannot form an interfacial organic-inorganic interpenetrating network; while eco-induction is mainly driven by alkalinity regulation and nutrient slow release, and has a low correlation with pore wall enhancement components.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A foamed concrete material for artificial reefs, characterized in that, The product comprises the following components by weight: 30-45 parts silicate cement, 30-50 parts slag powder, 10-25 parts fly ash, 5-15 parts metakaolin, 0.5-3.0 parts amphiphilic polymerizable precursor, 5-12 parts grafted dynamic alkalinity regulator, 3-8 parts eco-cascade-inducing microcapsules, 0.2-0.6 parts polycarboxylate superplasticizer, 1.5-2.5 parts foaming agent, and water, added at a water-cement ratio of 0.30-0.

35. The amphiphilic polymerizable precursor is a linear block copolymer containing perfluoropolyether segments, methacrylate end groups, and trialkoxysilane-terminated segments. The grafted dynamic alkalinity regulator is a grafted product in which the epoxy groups on the surface of fly ash microspheres and the phosphonic acid groups of aminotrimethylene phosphonic acid form COP bonds through ring opening. The ecological cascade attractant microcapsule has a core-shell structure. The core is a soluble nutrient core containing silicon, nitrogen, phosphorus and fish attractants. The inner layer is a gel layer formed by the hybridization of calcium alginate and chitin nanocrystals. The outer layer is a polyelectrolyte layer composed of alternating deposition of dopamine-modified chitosan and sodium alginate.

2. The foamed concrete material for artificial reefs according to claim 1, characterized in that, The preparation method of the grafted dynamic alkalinity regulator includes the following steps: A1: Mix fly ash microspheres with 1.0-2.0 mol / L hydrochloric acid at a solid-liquid ratio of 1 g:(8-15) mL and stir at 60-75℃ for 2-3 h. After the reaction is complete, filter and wash with deionized water until the filtrate is neutral. Then, mix the acid-washed fly ash with 1.0-2.0 mol / L sodium hydroxide solution and stir under reflux at 80-90℃ for 4-6 h. After the reaction is complete, filter and wash with deionized water until the pH of the filtrate is neutral. Then, vacuum dry at 100-110℃ for 6-8 h to obtain hydroxyl-activated fly ash for later use. A2: Prepare a mixed solvent of anhydrous isopropanol and toluene with a volume ratio of 2-4:1, add γ-glycidyl etheroxypropyltrimethoxysilane, adjust the pH to 4.0-4.5 by adding glacial acetic acid dropwise, and pre-hydrolyze at 25-30℃ for 25-35 min; add the hydroxyl-activated fly ash prepared in step A1, heat to 80-85℃ under nitrogen protection, and reflux with mechanical stirring for 6-10 h; after cooling, filter, ultrasonically wash three times with anhydrous ethanol and acetone respectively, and vacuum dry at 80℃ to obtain epoxy-functionalized fly ash for later use; A3: Mix 50% aminotrimethylenephosphonic acid aqueous solution with anhydrous isopropanol at a volume ratio of 1:3, and azeotropically distill until no water droplets are observed in the water separator and the system is clear, to obtain anhydrous aminotrimethylenephosphonic acid isopropanol solution; add triethylamine at a molar ratio of 2.8-3.2 times that of aminotrimethylenephosphonic acid, and stir and activate at 75-80℃ for 30 min; then add epoxy-functionalized fly ash, and heat to 85-90℃ under nitrogen protection, and stir vigorously under reflux for 12-16 h; after cooling, wash twice with anhydrous ethanol, twice with a dilute ammonia-ethanol mixture with pH=10 and a volume ratio of 1:9, and wash with deionized water until neutral, and vacuum dry at 80℃ for 12 h to obtain grafted dynamic alkalinity regulator.

3. The foamed concrete material for artificial reefs according to claim 2, characterized in that, In step A2, the amount of γ-glycidoxypropyltrimethoxysilane added is 10-20% of the mass of hydroxyl-activated fly ash.

4. The foamed concrete material for artificial reefs according to claim 2, characterized in that, In step A3, the mass of aminotrimethylenephosphonic acid in the anhydrous aminotrimethylenephosphonic acid isopropanol solution accounts for 15-35% of the mass of epoxy-functionalized fly ash.

5. The foamed concrete material for artificial reefs according to claim 1, characterized in that, The method for preparing the ecological cascade-inducing microcapsules includes the following steps: S1: Dissolve chitosan in a 1.0 wt% aqueous acetic acid solution to prepare a chitosan solution with a concentration of 1.5-2.5 wt%; add dopamine hydrochloride to the solution, with a molar ratio of dopamine to chitosan glycocycle units of 0.2-0.4:1; adjust the pH of the system to 5.5-6.0 with 1.0 mol / L NaOH solution, and stir the reaction at 40-50℃ in the dark for 12-18 h; after the reaction, dialyze the product in deionized water for 48 h using a dialysis bag with a molecular weight cutoff of 8000-14000 Da, and finally freeze-dry to obtain dopamine-modified chitosan powder, which is then sealed for later use. S2: To achieve the target molar ratio of silicon, nitrogen, and phosphorus in the final microcapsule core of (6-8):(16-24):1, sodium silicate, sodium nitrate, and potassium dihydrogen phosphate are dissolved in deionized water, and 1.0-3.0% of fish attractant by weight of the core is added. The mixture is stirred at 60-70°C to form a clear mixed solution, with the solid content controlled at 15-25 wt%. The solution is then sent to a centrifugal spray dryer, and the resulting free-flowing powder with a particle size controlled at 10-30 μm is the nutrient core. S3: Disperse the nutrient core powder obtained in step S2 in an aqueous solution of sodium alginate with a concentration of 1.0-1.5 wt%, and add 5-15% (by weight of sodium alginate) of chitin nanocrystals. Use a homogenizer to disperse the mixture at 5000-8000 r / min for 10-15 min to obtain a uniform suspension. Use a peristaltic pump or syringe pump to dropwise add the suspension into a mixed coagulation bath containing 0.3-0.5 mol / L CaCl2 and 0.05-0.1 mol / L sodium citrate at a flow rate of 5-10 mL / min. After the addition is complete, allow the mixture to stand for cross-linking for 20-40 min, filter, and wash three times with deionized water to obtain monolayer core microcapsules. S4: Prepare two polyelectrolyte solutions: Solution A is prepared by dissolving the dopamine-modified chitosan powder synthesized in step S1 in 0.1 mol / L acetate-sodium acetate buffer solution at pH 5.0, with a concentration of 1.0-2.0 mg / mL; Solution B is prepared by dissolving sodium alginate in deionized water, with a concentration of 1.0-1.5 mg / mL; redisperse the monolayer core microcapsules obtained in step S3 in solution A, and slowly stir and adsorb at 100-200 r / min for 10-15 min. After filtration, use deionized water... Wash with water; then disperse the microcapsules in solution B, adsorb for 10-15 min under the same conditions, wash, and complete one double-layer deposition cycle, recorded as 1 BL; repeat the above alternating deposition operation for 4-8 BLs; immerse the self-assembled microcapsules in artificial seawater simulation solution at pH=8.2, stand at 25-30℃ for 2-4 h, during which air is introduced at a rate of 0.5-1.0 L / min for 30-60 min; after filtration, vacuum dry or freeze dry at ≤40℃ to obtain the finished product of ecological cascade induced microcapsules.

6. The foamed concrete material for artificial reefs according to claim 5, characterized in that, In step S2, the fish attractant is selected from betaine, taurine or a mixture thereof; the parameters of the centrifugal spray dryer are: inlet air temperature of 180-210℃, outlet air temperature of 80-95℃, feed rate of 5-10mL / min, and atomization speed of 15000-20000r / min.

7. The foamed concrete material for artificial reefs according to claim 1, characterized in that, The preparation steps of the amphiphilic polymerizable precursor are as follows: Dry perfluoropolyether diols with a number-average molecular weight of 1000-2000 are mixed with isophorone diisocyanate at a molar ratio of 1:1.02-1.

08. Dibutyltin dilaurate is added, and the mixture is reacted at 60-75°C under nitrogen protection for 1.5-3 hours. The temperature is then lowered to 50-65°C, and hydroxyethyl methacrylate and hydroquinone (polymerization inhibitor) in equimolar amounts with residual -NCO are added. The reaction is continued for 1.5-3 hours until -NCO ≤ 0.1%. Isophorone is then added as needed. Ketone diisocyanate was added to make the amount of -NCO in the system 0.05-0.15 times that of the perfluoropolyether diol. The reaction was continued at 50-60℃ for 0.5-1h, and then the temperature was raised to 60-70℃. 3-aminopropyltriethoxysilane with a molar ratio of 1:1-1.05 to -NCO was added dropwise, and the reaction was continued for 1-2h until -NCO was completely eliminated, thus obtaining the target amphiphilic polymerizable precursor. The moisture content throughout the process was less than 200ppm.

8. A method for preparing foamed concrete material for artificial reefs as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Weigh silicate cement, slag powder, fly ash, metakaolin and grafted dynamic alkalinity regulator according to the proportion, put them into the mixer and dry mix for 2-5 minutes to obtain premixed powder; (2) Disperse the amphiphilic polymerizable precursor and polycarboxylate superplasticizer in water and stir at low speed until uniform to obtain a mixture; (3) Add the premixed powder from step (1) to the mixture from step (2), first stir slowly at 100-200 r / min for 1-2 min, then stir rapidly at 400-600 r / min for 2-3 min to form a uniform slurry; (4) Add the ecological cascade inducing microcapsules to the slurry from step (3) and stir at a low speed of 50-100 rpm for 1-2 minutes until the microcapsules are evenly dispersed. (5) Add foaming agent, stir at 200-400 rpm for 15-30 seconds and quickly pour into the mold, cover with film and let stand for 24-48 hours for initial curing, demold and steam curing: temperature 38-42℃, relative humidity ≥95%, curing for 48 hours; then immerse the test block in natural or artificial seawater and continue curing at 20-25℃ for 7 days to obtain the finished product.

9. The method for preparing foamed concrete material for artificial reefs according to claim 8, characterized in that, In step (2), a redox initiator is added to the water. The redox initiator is a mixture of ammonium persulfate and sodium bisulfite in a 1:1 molar ratio, and the amount used is 0.1-0.5% of the molar number of the amphiphilic polymerizable precursor.

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