Non-dispersing agent for keeping concrete flowing in water

Abstract

The invention discloses a non-dispersing agent for keeping concrete flowing in water, and belongs to the technical field of building materials, the non-dispersing agent comprises the following components by mass: 15-25% of an amphiphilic cellulose ether derivative; 10%-18% of a modified chitosan-acrylamide grafted copolymer; 8%-15% of a slow-release polycarboxylic acid water reducer; 5%-10% of nano silicon dioxide aerogel; 3%-8% of a bio-based delayed coagulation triggering agent; and 2%-5% of a self-repairing microbial capsule. Through a composite additive system, the loss rate of suspended solids is reduced to be within 1.2%, the slump loss within 2 hours is only 3%, and the problem of underwater segregation is solved; by utilizing a synergistic protection and self-repairing technology, the chloride ion diffusion coefficient is reduced by nearly 3 times, 0.3 mm cracks are repaired in 7 days, and the elastic modulus retention rate after freeze-thaw cycle reaches 91%. The underwater strength retention rate exceeds 95%, and the strength in 7 days reaches 80% of a design value. The ratio of the bio-based raw materials is 43%, the construction efficiency is improved by 87.5%, the cost in 30 years is reduced by 36.7%, and the method is widely applicable to environments and fills the blank of industrial test standards.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a concrete that can keep flowing in water without dispersing. Background Art

[0002] Underwater concrete pouring faces complex environments such as water erosion, pressure fluctuations, and ion erosion. These requirements require concrete to be resistant to dispersion, preventing cement paste loss (traditional technology has a suspended matter loss rate > 5%); self-compacting, achieving uniform filling without vibration (ordinary concrete has a gap pass rate < 0.6); durable, resisting chloride ion penetration (conventional admixture Cl⁻ diffusion coefficient > 5×10⁻¹²m² / s); and strength retention: underwater curing strength must reach at least 90% of the strength in air (traditional technology only achieves 75%-85%). Defects of existing technology: (1) Insufficient anti-dispersant performance: Cellulose ethers (such as HPMC): High dosage (>3%) leads to poor fluidity and slow static viscosity recovery (>5min), making them unable to adapt to dynamic water flow environments; Flocculants (such as polyacrylamide): Cationic PAM easily reacts with SO4²⁻ in cement and becomes ineffective, and residual monomers pollute the environment (acrylamide residue >0.01%); (2) Uncontrollable release of water reducer: Traditional polycarboxylate water reducers release quickly in alkaline environments (release > 80% in 30 minutes), resulting in a large loss of fluidity over time (slump loss > 15% in 2 hours); (3) Limitations of self-repair technology: Chemical crystallization repair agents (such as penetrating crystallization waterproofing agents) can only repair cracks less than 0.1mm and rely on a continuous water supply; microbial repair systems are easily inhibited by the high alkalinity of concrete (pH>12), and the spore survival rate is less than 50%; (4) Environmental defects: The production of naphthalene-based and melamine-based water reducers consumes high energy (>3 tons of CO2 / ton of product) and contains harmful substances such as formaldehyde.

[0003] Based on this, the present invention designs a concrete that remains fluid in water without dispersant to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned problems and to provide a concrete that remains fluid in water and does not disperse.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A concrete agent that keeps it fluid and non-dispersible in water, comprising: Amphiphilic cellulose ether derivatives 15%~25% Modified chitosan-acrylamide graft copolymer 10%~18% Slow-release polycarboxylate water reducer 8%~15% Nano-silica aerogel 5%~10% Bio-based retarding trigger 3%~8% Self-repairing microbial capsules 2%~5% Remainder of composite mineral carrier (ultrafine slag + silica fume).

[0006] As a further description of the above technical solution: The amphiphilic cellulose ether derivative is an esterification product of hydroxypropyl methylcellulose and dodecyl succinic anhydride, with a degree of substitution controlled at 0.3-0.6 and an apparent viscosity of an aqueous solution of 8000-12000 mPa·s (2% concentration, 20°C).

[0007] As a further description of the above technical solution: The modified chitosan copolymer is prepared by: a) chitosan is pretreated with a deacetylation degree of ≥90%, and then free radical graft polymerization is carried out with acrylamide monomer under nitrogen protection; b) introducing epoxypropyltrimethylammonium chloride for quaternization modification, with a cationic degree of 1.2~1.8mmol / g; c) The intrinsic viscosity of the final product is controlled within the range of 450-650 mL / g (1 M NaCl, 25°C).

[0008] As a further description of the above technical solution: The slow-release polycarboxylate water-reducing agent has a core-shell structure: Core: Highly adsorbable polycarboxylic acid containing phosphate groups (adsorption capacity ≥ 18 mg / g cement); Shell: pH-responsive polyethylene glycol-ε-caprolactone copolymer, which gradually decomposes when pH>10.5.

[0009] As a further description of the above technical solution: The bio-based retarding trigger is composed of the following: Complex of gluconolactone and calcium ligninsulfonate (molar ratio 1:0.6~0.8); Sodium alginate-coated nano-calcium carbonate particles (D50 = 200-400 nm); A complex chelating agent of trisodium citrate and potassium tartrate.

[0010] As a further description of the above technical solution: The self-repairing microbial capsule adopts a three-layer coating technology: Inner layer: Bacillus sphaericus co-immobilized with nutrient solution; Middle layer: pH-sensitive gelatin-gum arabic microcapsules; Outer layer: polyurethane waterproof protective film.

[0011] As a further description of the above technical solution: The composite mineral carrier satisfies the following gradation: Ultrafine slag (specific surface area ≥ 600m² / kg) accounts for 60%~70% of the total carrier; Silica fume (SiO2 content ≥ 92%, average particle size 0.1~0.3μm) accounts for 30%~40%; After mechanical activation treatment, the two formed a porous composite structure (porosity 35%~45%).

[0012] As a further description of the above technical solution: The application features include The dosage is 1.8%~2.5% of the total mass of the cementitious material; Suitable for self-compacting underwater concrete pouring within a water depth of 30m; Initial slump ≥650mm, 2h underwater anti-dispersion (suspended matter content) ≤1.2%; The 28d compressive strength retention rate is ≥95% (compared with curing in air).

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. A composite system of an amphiphilic cellulose ether derivative (viscosity recovery time <2 minutes) and a modified chitosan copolymer (zeta potential of +25mV) significantly reduces suspended solids loss from >5% in conventional technologies to ≤1.2% (measured data in Example 2: 0.9%) through intermolecular synergistic adsorption, fundamentally eliminating the problem of cement slurry loss during underwater application. Combined with a core-shell structured, this system achieves precise release of the admixture (85% release rate within 60 minutes), ensuring an initial concrete slump of ≥650mm and a 2-hour slump loss of only 3%, far exceeding the 15% or more loss rate of conventional technologies. This ensures that the concrete maintains excellent self-compacting pouring properties underwater, effectively addressing the industry challenges of segregation and difficult forming during underwater construction.

[0014] 2. Utilizing the synergistic effect of cationic chitosan (chloride ion adsorption capacity of 1.8 mmol / g) and nano-aerogel, a highly effective chloride ion barrier is constructed, reducing the chloride ion diffusion coefficient to 1.8×10⁻¹²m² / s, nearly three times the efficiency of traditional technologies, significantly delaying steel corrosion. The three-layer coated microbial capsules automatically activate at the crack site (pH ≤ 9), eliminating the need for a continuous external water supply. Within 7 days, they can repair a 0.3mm crack, achieving a 92% repair rate, far exceeding the 0.1mm repair limit of chemical repair agents. After 300 freeze-thaw cycles, the concrete's relative dynamic elastic modulus remained at 91%, a 23 percentage point increase compared to the control group. By optimizing the pore structure, the proportion of harmful pores was reduced from 25% to 10%, significantly enhancing frost resistance and effectively extending the service life of concrete structures in underwater environments.

[0015] 3. Under underwater construction conditions, the concrete's 28-day compressive strength retention rate is ≥95% (measured at 96.5% in Example 2), significantly surpassing the 75%-85% achieved with conventional technologies. This makes it particularly suitable for extreme conditions such as deep-sea high pressure (0.3 MPa). Its rapid early strength development, reaching 80% of the design value within just seven days, compared to only 60%-70% with conventional technologies, effectively shortens construction schedules, reduces underwater work time, and significantly improves construction safety and efficiency.

[0016] 4. Bio-based raw materials account for as much as 43%, and carbon emissions during the production process are 38% lower than traditional naphthalene-based admixtures. CO2 emissions for every ton of product produced are less than 1.2 tons, which fully meets the green building material standards and contributes to the sustainable development of the construction industry. During the construction process, with its excellent self-compacting properties, there is no need for underwater vibration, and the construction efficiency is increased from 8m³ / h to 15m³ / h, an efficiency increase of 87.5%; the application of self-repairing technology reduces the cost of crack grouting by 50%. It has been calculated that within the 30-year life cycle, the total cost per cubic meter of concrete will drop from 1,220 yuan to 850 yuan, a reduction of 36.7%, bringing significant cost savings to engineering construction.

[0017] 5. This technology can be stably applied in complex underwater environments with a pH range of 8-13, a water temperature of 5-35°C, and a water depth of ≤30m. This breaks through the traditional technology's reliance on strongly alkaline environments (pH>12), greatly expanding the application range of underwater concrete. The product strictly complies with international mainstream standards such as JTS202-2011 and ASTMC942. At the same time, it innovatively establishes anti-dispersion test methods under dynamic water flow and high-pressure environments, filling the industry's technical gaps and providing more scientific and reliable technical standards and application solutions for underwater concrete construction. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] The present invention provides a technical solution: a concrete that remains fluid in water and does not disperse, comprising: the following components in percentage by mass: Amphiphilic cellulose ether derivatives 15%~25% Modified chitosan-acrylamide graft copolymer 10%~18% Slow-release polycarboxylate water reducer 8%~15% Nano-silica aerogel 5%~10% Bio-based retarding trigger 3%~8% Self-repairing microbial capsules 2%~5% Remainder of composite mineral carrier (ultrafine slag + silica fume).

[0020] The amphiphilic cellulose ether derivative is an esterification product of hydroxypropyl methylcellulose and dodecyl succinic anhydride, with a degree of substitution controlled at 0.3-0.6 and an apparent viscosity of the aqueous solution of 8000-12000 mPa·s (2% concentration, 20°C); The modified chitosan copolymer is prepared by: a) chitosan is pretreated with a deacetylation degree of ≥90%, and then free radical graft polymerization is carried out with acrylamide monomer under nitrogen protection; b) introducing epoxypropyltrimethylammonium chloride for quaternization modification, with a cationic degree of 1.2~1.8mmol / g; c) The intrinsic viscosity of the final product is controlled within 450-650 mL / g (1 M NaCl, 25°C); The slow-release polycarboxylate water-reducing agent has a core-shell structure: Core: Highly adsorbable polycarboxylic acid containing phosphate groups (adsorption capacity ≥ 18 mg / g cement); Shell: pH-responsive polyethylene glycol-ε-caprolactone copolymer, which gradually decomposes when pH>10.5.

[0021] The bio-based retarding trigger is composed of the following: Complex of gluconolactone and calcium ligninsulfonate (molar ratio 1:0.6~0.8); Sodium alginate-coated nano-calcium carbonate particles (D50 = 200-400 nm); Complex chelating agent of trisodium citrate and potassium tartrate The self-repairing microbial capsule adopts a three-layer coating technology: Inner layer: Bacillus sphaericus co-immobilized with nutrient solution; Middle layer: pH-sensitive gelatin-gum arabic microcapsules; Outer layer: polyurethane waterproof protective film.

[0022] The composite mineral carrier satisfies the following gradation: Ultrafine slag (specific surface area ≥ 600m² / kg) accounts for 60%~70% of the total carrier; Silica fume (SiO2 content ≥ 92%, average particle size 0.1~0.3μm) accounts for 30%~40%; After mechanical activation treatment, the two formed a porous composite structure (porosity 35%~45%).

[0023] According to the above application characteristics include: The dosage is 1.8%~2.5% of the total mass of the cementitious material; Suitable for self-compacting underwater concrete pouring within a water depth of 30m; Initial slump ≥650mm, 2h underwater anti-dispersion (suspended matter content) ≤1.2%; The 28d compressive strength retention rate is ≥95% (compared with curing in air).

[0024] Example 1: Formulation and preparation Formula composition (mass percentage) Preparation process (1) Synthesis of amphiphilic cellulose ether derivatives Hydroxypropyl methylcellulose (HPMC) and dodecyl succinic anhydride were mixed in a molar ratio of 1:0.4, and the mixture was esterified at 80°C for 6 hours. The degree of substitution was controlled to 0.45, and the product was spray-dried to obtain a white powder.

[0025] Esterification reaction of amphiphilic cellulose ether Selection of esterifying agent: The molar ratio of dodecyl succinic anhydride (DSA) to HPMC is 0.4:1. Below this ratio, the degree of substitution is insufficient (<0.3), and above this ratio, the water solubility of the product decreases (cloud point <40°C).

[0026] Reaction control: The reaction was carried out at 80°C for 6 hours. The intensity of the ester carbonyl peak at 1720 cm⁻¹ was monitored by online FTIR to ensure that the degree of substitution reached 0.45±0.02.

[0027] Spray drying parameters: inlet temperature 180°C, outlet temperature 85°C, ensuring powder moisture content ≤ 2%, particle size D50 = 45 μm.

[0028] (2) Preparation of modified chitosan copolymer Chitosan with a deacetylation degree of 92% was dissolved in 2% acetic acid solution under nitrogen protection, and acrylamide (chitosan: monomer = 1:3) and ammonium persulfate initiator were added and reacted at 60°C for 4 hours; Add epoxypropyltrimethylammonium chloride (quaternizing agent), adjust the pH to 8.5, react at 50°C for 2 hours, dialyze and dry to obtain a cationic copolymer.

[0029] Chitosan graft copolymerization Optimization of free radical initiation: ammonium persulfate (APS) concentration 0.5wt%, initiation temperature 60℃, grafting efficiency reached 78% (nitrogen content change calculated by elemental analysis).

[0030] Quaternization modification: The amount of epoxypropyltrimethylammonium chloride used was 30% of the mass of chitosan. After the reaction, the cationicity increased from 0.2 mmol / g to 1.5 mmol / g (determined by colloid titration).

[0031] (3) Synthesis of slow-release polycarboxylate water reducer Core synthesis: Methacrylic acid and allyl phosphate are copolymerized (molar ratio 5:1) to produce polycarboxylic acid containing phosphoric acid groups; Shell coating: Polyethylene glycol (PEG2000) and ε-caprolactone (molar ratio 1:2) were ring-opening polymerized to form a pH-sensitive shell; The core is wrapped with the shell through emulsion polymerization to produce core-shell structured particles (particle size 80~120nm).

[0032] Preparation of core-shell water reducer Core design: Phosphate groups account for 15% (XPS analysis), and the adsorption capacity reaches 22 mg / g cement (adsorption isotherm determined by UV spectrophotometry).

[0033] Shell responsiveness: PEG-PCL copolymer, composed of 65% ε-caprolactone, was completely degraded within 48 hours at pH 10.5 (GPC monitoring showed a decrease in molecular weight from 8000 Da to 2000 Da).

[0034] (4) Self-repairing microbial capsule encapsulation Inner layer: Bacillus sphaericus spores are mixed with glucose and calcium nitrate nutrient solution and adsorbed on diatomaceous earth carrier; Middle layer: gelatin-gum arabic (mass ratio 3:1) cross-linked at pH 4.5 to form microcapsules that encapsulate the bacteria; Outer layer: Spray polyurethane prepolymer (Desmodur® L75) to form a 5~10μm waterproof membrane.

[0035] Microbial encapsulation Nutrient solution formula: glucose: calcium nitrate: yeast extract = 5:3:1 (mass ratio), ensuring that the calcium carbonate production within 72 hours after spore recovery is ≥1.2g / L; Polyurethane coating: film thickness 8μm (SEM measurement), water permeability <0.1g / (m²·h) (ASTME96 standard), compressive strength ≥15MPa (micro-force tester).

[0036] (5) Compounding of composite admixtures Homogenize the components and composite mineral carrier (ultrafine slag and silica fume activated by ball milling for 2 hours) in a dry powder mixer for 30 minutes according to the formula ratio, and control the moisture content to ≤1%; Example 2: Application Performance Testing Concrete mix ratio (kg / m³) Durability improvement verification 1. Chloride ion curing ability Curing path: a) Cationic chitosan adsorbs Cl⁻ via ion exchange (adsorption capacity 1.8 mmol / g); b) Physical retention of Cl⁻ in nanoaerogel pores (Zeta potential -18 mV).

[0037] Measured data: 2. Shrinkage compensation mechanism Expansion source: Nano calcium carbonate particles hydrate to form ettringite (XRD detection characteristic peak d = 9.73Å) Shrinkage comparison: 3. Microstructure Characterization (1) SEM-EDS analysis Interfacial transition zone (ITZ): The ITZ thickness of the experimental group was 1.2 μm (2.8 μm in the control group), the Ca / Si ratio decreased from 2.1 to 1.5, and the CSH gel was denser.

[0038] Crack repair products: EDS shows that the Ca content in the repaired area is 32.5wt%, O 47.1wt%, and C 15.3wt% (characteristic proportion of calcite).

[0039] (2) Mercury intrusion pore analysis 4. Full life cycle cost analysis Engineering Application Guide Mixing process Dry mixing stage: premix the composite admixture with the cementitious material for 60 seconds (speed 45 rpm) Wet mixing stage: add water and stir for 120s (speed 60rpm), control the outlet temperature ≤35℃ Key points of underwater pouring The buried depth of the conduit is always ≥1.5m, and the pouring rate is maintained at 8-12m³ / h When the ambient water temperature is greater than 5°C, the initial slump can be lowered to 620mm to reduce the risk of segregation. Quality acceptance standards Construction parameters and test results Technical effect analysis Anti-dispersion mechanism Dynamic viscosity adjustment: The hydrophilic chain segments of the amphiphilic cellulose ether form a hydrogen bond network with the cationic groups of chitosan, which dissociates under shear force (pumping) (viscosity drops to 1500mPa·s) and quickly reorganizes after entering water and standing (viscosity recovers to 9500mPa·s), effectively locking the cement particles.

[0040] Intelligent slow-release water reduction: The water-reducing agent shell decomposes at pH>10.5 (mid-stage of cement hydration), and the release rate reaches 85% within 60 minutes, ensuring that the fluidity lasts for more than 2 hours.

[0041] Self-repair function verification When water seeps into the cracks and the pH drops below 9, the gelatin-gum arabic microcapsules dissolve, releasing Bacillus metabolism to produce CO3²⁻, which combines with Ca²+ to form calcite (XRD detects a characteristic peak of CaCO3), filling a 0.3mm crack within 7 days.

[0042] Environmental protection and economy Bio-based ingredients account for 43%, and carbon emissions from the production process are 38% lower than those from traditional naphthalene-based admixtures; Maintenance costs per cubic meter of concrete are reduced by 52% (no underwater vibration and post-crack grouting are required).

[0043] Example 3: Verification of adaptability to deep-sea environment 1. Test environment and equipment configuration Pressure simulation system A cylindrical high-pressure curing tank (2m in diameter, 5m in height) is used, equipped with a hydraulic servo control system, which can accurately simulate the water pressure at a depth of 0~50m (0~0.5MPa), with a pressure fluctuation error of ≤±0.02MPa.

[0044] Water temperature control: Maintain a constant temperature of 10±1℃ (simulating deep sea low temperature environment) through an external circulation cooling system.

[0045] Concrete pouring device Conduit casting equipment: a steel conduit with an inner diameter of 250 mm, equipped with an anti-recoil valve, and the bottom of the conduit is 1.2 m away from the bottom of the pool.

[0046] Automatic vibration system: two modes are set: no vibration (to verify self-compacting performance) and low-frequency vibration (5Hz, comparison group).

[0047] 2. Specimen preparation and test grouping Specimen specifications Compressive strength test piece: 150mm×150mm×150mm cube, 6 pieces per group Anti-segregation test piece: Prepare U-shaped tube test mold according to JTS202-2011 (inner diameter 100mm, height 1.5m) Durability test piece: 100mm×100mm×400mm prism, 4 pieces per group Comparison group settings 3. Key Performance Test Methods 3.1. Segregation resistance test (U-tube method) step: a. Pour fresh concrete into the left side of the U-shaped tube and let it stand for 30 minutes to simulate underwater stay. b. Open the middle valve and record the height difference of concrete on both sides ΔH c. Collect the cement slurry seeping from the bottom of the pipe, dry it at 105℃ and weigh the loss rate Calculation formula: Cement slurry loss rate = mass of seepage slurry | total slurry mass of specimen × 100% Measured data: 3.2. Intensity Development Monitoring Maintenance system: The high-pressure curing tank has a constant pressure of 0.3MPa and a water temperature of 10°C. Remove the mold after 7 days and continue curing until 28 days Test equipment: Microcomputer-controlled electro-hydraulic servo press (3000kN range, accuracy ±0.5%) Intensity curve: 3.3 Freeze-thaw cycle durability test Test conditions: According to GB / T50082-2009 quick freezing method, cycle temperature -18℃~+5℃ Each cycle is 2 hours (freezing 1 hour + melting 1 hour), a total of 300 times Evaluation indicators: Mass loss rate: Relative dynamic elastic modulus: Test results: 4. Mechanism Analysis and Engineering Value 4.1 Source of Anti-segregation Advantage Nano-aerogel adsorption effect: Nano-SiO2 aerogel with a specific surface area of 300m² / g captures free water through physical adsorption, reducing the tendency of slurry segregation (Zeta potential increases from -35mV to -18mV).

[0048] Cationic complexation: The quaternary ammonium groups (+25 mV) of the chitosan copolymer combine with the negative charges on the surface of cement particles to form a dense flocculated structure (SEM shows floc size ≤ 10 μm).

[0049] 4.2 Key to Improving Strength Retention Rate Synergy of slow-release water-reducing agent: The core-shell water-reducing agent had a release rate of 92% at 7 days, continuously dispersed cement particles, and promoted the densification of CSH gel (the porosity measured by mercury intrusion was only 8.7%, while that of the control group was 14.2%).

[0050] 4.3 Breakthrough in freeze-thaw durability Self-healing system activation: freeze-thaw cracks (average width 0.15 mm) triggered the release of microbial capsules, and XRD detected new calcite in the cracks (CaCO3 content reached 18.7 wt%).

[0051] Optimized pore structure: The bubble spacing coefficient was reduced to 0.12mm (control group 0.25mm), significantly improving frost resistance (durability index DF = 95 calculated according to Powers formula) V. Comparison of Economic Benefits Through precise environmental simulation and multi-dimensional performance testing, this verification test confirmed the comprehensive performance advantages of the admixture of the present invention under deep-sea high-pressure and low-temperature conditions, providing a reliable technical solution for projects such as cross-sea bridge pile foundations and submarine immersed tube tunnels.

[0052] Data support and comparative verification: in conclusion: This invention, through a multi-component collaborative design, overcomes the technical challenges of achieving optimal balance between anti-dispersion, fluidity, durability, and environmental performance in underwater concrete. Measured performance surpasses existing technologies and industry standards. Its high performance, long life, and low maintenance cost offer innovative material solutions for deep-sea engineering, cross-sea transportation hubs, and marine resource development, driving the rapid development of underwater concrete technology towards intelligent and green development.

[0053] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A concrete that remains fluid in water and does not dispersant, characterized in that: include: It is composed of the following components in percentage by mass: Amphiphilic cellulose ether derivatives 15%~25% Modified chitosan-acrylamide graft copolymer 10%~18% Slow-release polycarboxylate water reducer 8%~15% Nano-silica aerogel 5%~10% Bio-based retarding trigger 3%~8% Self-repairing microbial capsules 2%~5% Remainder of composite mineral carrier (ultrafine slag + silica fume).

2. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The amphiphilic cellulose ether derivative is an esterification product of hydroxypropyl methylcellulose and dodecyl succinic anhydride, with a degree of substitution controlled at 0.3-0.6 and an apparent viscosity of an aqueous solution of 8000-12000 mPa·s (2% concentration, 20°C).

3. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The modified chitosan copolymer is prepared by: a) chitosan is pretreated with a deacetylation degree of ≥90%, and then free radical graft polymerization is carried out with acrylamide monomer under nitrogen protection; b) introducing epoxypropyltrimethylammonium chloride for quaternization modification, with a cationic degree of 1.2~1.8mmol / g; c) The intrinsic viscosity of the final product is controlled within the range of 450-650 mL / g (1 M NaCl, 25°C).

4. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The slow-release polycarboxylate water-reducing agent has a core-shell structure: Core: Highly adsorbable polycarboxylic acid containing phosphate groups (adsorption capacity ≥ 18 mg / g cement); Shell: pH-responsive polyethylene glycol-ε-caprolactone copolymer, which gradually decomposes when pH>10.

5.

5. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The bio-based retarding trigger is composed of the following: Complex of gluconolactone and calcium ligninsulfonate (molar ratio 1:0.6~0.8); Sodium alginate-coated nano-calcium carbonate particles (D50 = 200-400 nm); A complex chelating agent of trisodium citrate and potassium tartrate.

6. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The self-repairing microbial capsule adopts a three-layer coating technology: Inner layer: Bacillus sphaericus co-immobilized with nutrient solution; Middle layer: pH-sensitive gelatin-gum arabic microcapsules; Outer layer: polyurethane waterproof protective film.

7. The concrete according to claim 1, wherein the concrete remains fluid in water and does not disperse. The composite mineral carrier satisfies the following gradation: Ultrafine slag (specific surface area ≥ 600m² / kg) accounts for 60%~70% of the total carrier; Silica fume (SiO2 content ≥ 92%, average particle size 0.1~0.3μm) accounts for 30%~40%; After mechanical activation treatment, the two formed a porous composite structure (porosity 35%~45%).

8. A concrete prepared according to any one of claims 1 to 7 which remains fluid in water and does not dispersant, characterized in that The application features include The dosage is 1.8%~2.5% of the total mass of the cementitious material; Suitable for self-compacting underwater concrete pouring within a water depth of 30m; Initial slump ≥650mm, 2h underwater anti-dispersion (suspended matter content) ≤1.2%; The 28d compressive strength retention rate is ≥95% (compared with curing in air).

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