Seawall crack plugging underwater grouting material and preparation method thereof

Abstract

The present application belongs to the field of underwater hydraulic repair materials, and provides a seawall crack plugging underwater grouting material and a preparation and plugging method thereof. The present application is an X@Y core-shell cement-composite hydrogel intermediate with superfine quick-hardening sulphoaluminate cement particles as the core and calcium ion cross-linked sodium alginate-sodium carboxymethyl cellulose composite gel as the shell layer, and is compounded with silica powder, anhydrous calcium sulfate, sodium lignosulfonate, graded quartz sand and deionized water to form a mixable underwater grouting system. The slurry has the properties of construction flow maintenance, underwater erosion resistance, early skeleton formation, late strength development and flow maintenance ability after sealed moisture storage, and solves the problem that construction fluidity and underwater dispersion resistance, storage stability and plugging response are difficult to be considered at the same time, and is suitable for seawall crack and wet hydraulic structure plugging repair.

Description

Technical Field

[0001] This invention relates to the field of underwater hydraulic engineering repair materials, specifically to an underwater grouting material for sealing seawall cracks and its preparation method. Background Technology

[0002] Seawalls, revetments, wharf foundations, and tidal zone concrete structures are subjected to long-term seawater immersion, wave erosion, alternating wet and dry conditions, and salt corrosion. Once cracks form, they can easily lead to the expansion of seepage channels, localized scouring, steel reinforcement corrosion, and decreased structural durability. When underwater grouting materials are used to seal such cracks, mixing, transportation, injection, and hardening must be completed under conditions of incomplete drainage or difficulty in establishing cofferdams. Therefore, the materials must possess fluidity suitable for pumping and filling fine cracks, while maintaining grout cohesion and particle stability after entering the water body to prevent the cementitious components from being carried away by the water flow. For seawall crack repair scenarios, the materials should also consider early skeleton formation, later strength development, particle size distribution filling, wet cohesion, and moisture-proof stability during dry powder storage to meet the engineering requirements of short on-site construction windows, large crack size variations, and continuous hydrodynamic disturbances.

[0003] Existing underwater grouting technologies typically improve fluidity by enhancing water-reducing and dispersing capabilities, or enhance underwater stability through thickening, flocculation, and anti-dispersing additives. However, these two approaches often constrain each other in terms of rheological structure. Chinese patent CN106747146A discloses an underwater anti-dispersion cement-based grout and its preparation method. The grout consists of sulfoaluminate cement, silicate cement, aggregate, water-reducing agent, early-strength agent, retarder, defoamer, leveling agent, and anti-dispersion agent. The design reflects the idea of ​​solving underwater construction problems by combining a cementitious system and an anti-dispersion agent. However, this type of system still relies heavily on the agglomeration state formed by the admixture immediately after mixing. There are still difficulties in balancing dry storage, fine crack injection, and sealing response after water contact. Studies on the scour resistance of high-flow underwater concrete have shown that the concentration of anti-scour admixture, water-cement ratio, and cementitious material composition all affect the consistency of underwater scour resistance and flow, indicating that simply adjusting the formula often cannot simultaneously solve the problems of flow retention and underwater anti-dispersion. Summary of the Invention

[0004] The purpose of this invention is to provide an underwater grouting material for sealing seawall cracks and its preparation method, thereby solving the problems of difficulty in balancing the construction fluidity and underwater anti-dispersion properties, as well as the difficulty in balancing storage stability and underwater sealing performance of current underwater grouting materials.

[0005] This invention places ultrafine, rapid-hardening sulfoaluminate cement particles X within a calcium ion-crosslinked sodium alginate-sodium carboxymethyl cellulose composite gel shell, and matches them with silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and graded quartz sand. This allows the dry particle stability, mixing fluidity, water retention and erosion resistance, and cement skeleton formation to mutually correct each other within the same system, reducing the adverse side effects of simple dispersion or simple thickening.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An underwater grouting material for sealing seawall cracks, the underwater grouting material comprising a dry powder component as a feed component and a liquid component as a mixing liquid;

[0008] Based on the amount of feed used to prepare 100.00 parts by weight of the dry powder component, the dry powder component comprises:

[0009] X@Y core-shell cement-composite hydrogel intermediate 45.00-60.00 parts by weight;

[0010] 2.00-8.00 parts by weight of silica powder;

[0011] 0.50-5.00 parts by weight of anhydrous calcium sulfate;

[0012] Sodium lignosulfonate 0.05-0.80 parts by weight;

[0013] The quartz sand is added to make up to 100.00 parts by weight, and the total amount of the X@Y core-shell cement-composite hydrogel intermediate, the silica powder, the anhydrous calcium sulfate and the sodium lignosulfonate is 55.00-70.00 parts by weight.

[0014] The liquid component is deionized water, and the amount of deionized water relative to 100.00 parts by weight of the dry powder component is 25.00-45.00 parts by weight.

[0015] The X@Y core-shell cement-composite hydrogel intermediate is a core-shell particle formed with ultrafine rapid hardening sulfoaluminate cement particles X as the core and calcium ion crosslinked sodium alginate-carboxymethyl cellulose sodium composite gel shell Y as the shell.

[0016] Furthermore, the shell Y is formed of sodium alginate, sodium carboxymethyl cellulose, and calcium chloride calculated as anhydrous calcium chloride;

[0017] The D50 of the ultrafine rapid hardening sulfoaluminate cement particles X is 2.00-15.00 μm, the thickness of the shell layer Y is 0.20-5.00 μm, and the coating rate of the shell layer Y on the surface of the ultrafine rapid hardening sulfoaluminate cement particles X is 70.00-98.00%.

[0018] Furthermore, the X@Y core-shell cement-composite hydrogel intermediate is prepared through the following steps:

[0019] A1. Prepare or provide the ultrafine rapid hardening sulfoaluminate cement particles X, wherein the ultrafine rapid hardening sulfoaluminate cement particles X have a D50 of 2.00-15.00 μm, a D90 of 8.00-35.00 μm, and the D90 is not less than the D50 in the same particle size distribution, and the moisture content is 0.10-3.00 wt%.

[0020] A2. Preparation of hydrogel precursor solution: Sodium alginate, sodium carboxymethyl cellulose, and sodium chloride are added to deionized water and stirred at 20.00-35.00℃ for 0.50-3.00h to obtain a hydrogel precursor solution with a pH of 7.00-8.50; wherein the mass fraction of sodium alginate in the hydrogel precursor solution is 0.10-2.00wt%, the mass fraction of sodium carboxymethyl cellulose in the hydrogel precursor solution is 0.05-1.00wt%, and the mass fraction of sodium chloride in the hydrogel precursor solution is 1.00-5.00wt%.

[0021] A3. In-formulation coating: Mix 100.00 parts by weight of the ultrafine rapid-hardening sulfoaluminate cement particles X with 20.00-80.00 parts by weight of the hydrogel precursor liquid, and shear disperse at 20.00-35.00℃ for 5.00-30.00 min; then add calcium chloride aqueous solution, wherein the mass fraction of calcium chloride in the calcium chloride aqueous solution is 2.50-8.00 wt% based on anhydrous calcium chloride, and the amount of calcium chloride relative to 100.00 parts by weight of the ultrafine rapid-hardening sulfoaluminate cement particles X is 0.05-2.50 parts by weight based on anhydrous calcium chloride, and continue to react at 20.00-35.00℃ for 10.00-60.00 min to form wet X@Y core-shell particles.

[0022] A4. Post-processing: The wet X@Y core-shell particles are filtered or centrifuged, washed with deionized water 1-3 times, and dried at 35.00-55.00℃ for 2.00-8.00h to obtain the X@Y core-shell cement-composite hydrogel intermediate.

[0023] A5. The water content of the obtained X@Y core-shell cement-composite hydrogel intermediate is 0.50-5.00 wt%.

[0024] Furthermore, the hydrogel precursor solution in step A2 is prepared through the following steps:

[0025] B1. Add sodium chloride to deionized water at a feed amount of 1.00-5.00 wt% of sodium chloride in the obtained hydrogel precursor solution to obtain a brine phase.

[0026] B2. Add sodium alginate and sodium carboxymethyl cellulose to the brine phase, wherein the mass ratio of sodium alginate to sodium carboxymethyl cellulose is 1.00:0.20-1.00:1.50.

[0027] B3. Stir at 20.00-35.00℃ for 0.50-3.00h, and let stand for 0.50-2.00h to remove bubbles, to obtain the hydrogel precursor solution.

[0028] B4. The quality control parameters for the obtained hydrogel precursor solution are: pH value of 7.00-8.50, total polymer mass fraction of 0.15-3.00wt%, and undissolved matter mass fraction of no more than 0.50wt%.

[0029] Furthermore, the ultrafine rapid-hardening sulfoaluminate cement particles X in step A1 are prepared through the following steps:

[0030] C1. Provides rapid-hardening sulfoaluminate cement.

[0031] C2. The rapid-hardening sulfoaluminate cement is dried at 40.00-80.00℃ for 1.00-6.00h to obtain a moisture content of 0.10-3.00wt%.

[0032] C3. The dried rapid-hardening sulfoaluminate cement is dry-milled or air-jet-milled for 15.00-90.00 min and classified to obtain ultrafine rapid-hardening sulfoaluminate cement particles X with D50 of 2.00-15.00 μm and D90 of 8.00-35.00 μm, wherein the D90 is not less than the D50 in the same particle size distribution.

[0033] C4. The quality control parameters for the ultrafine rapid hardening sulfoaluminate cement particles X are: moisture content of 0.10-3.00wt% and sieve residue of not more than 5.00wt%.

[0034] Furthermore, the post-processing in step A4 includes:

[0035] D1. Centrifuge the wet X@Y core-shell particles at a speed of 500-3000 rpm for 2.00-10.00 min, or filter them under a vacuum of 0.02-0.08 MPa for 5.00-30.00 min.

[0036] D2. Wash the separated wet X@Y core-shell particles with deionized water 1-3 times, with the amount of water used for each wash being 0.50-3.00 times the mass of the separated wet X@Y core-shell particles.

[0037] D3. Dry at 35.00-55.00℃ for 2.00-8.00h to obtain X@Y core-shell cement-composite hydrogel intermediate with a water content of 0.50-5.00wt%.

[0038] D4. The agglomeration rate of the dried X@Y core-shell cement-composite hydrogel intermediate is not higher than 5.00 wt%, and the change rate of D50 after redispersibility is not higher than 20.00%.

[0039] Furthermore, the quartz sand includes fine-graded quartz sand with a particle size d of 0.05mm ≤ d < 0.30mm and medium-graded quartz sand with a particle size d of 0.30mm ≤ d ≤ 1.20mm, and the mass ratio of the fine-graded quartz sand to the medium-graded quartz sand is 1.00:0.80-1.00:3.00;

[0040] The dry powder component of the underwater grouting material is mixed with the liquid component to form an underwater grouting wet slurry. The initial fluidity of the underwater grouting wet slurry is 180.00-260.00 mm, the fluidity retention rate is 70.00-95.00% after 30 minutes, the underwater scouring mass loss is 0.50-10.00 wt%, the 1-day compressive strength is 8.00-25.00 MPa, and the 28-day compressive strength is 35.00-70.00 MPa.

[0041] As a concept of this invention, the present invention employs a design combining an X@Y core-shell cement-composite hydrogel intermediate with silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and graded quartz sand, primarily to achieve a synergistic balance between construction fluidity and underwater anti-dispersion properties. Existing underwater grouting materials often rely on dispersion-reducing water and low cohesive structures to improve fluidity, which easily leads to the separation of cementitious particles by underwater scouring; to improve anti-dispersion properties, high-viscosity hydrophilic networks are often introduced, potentially increasing mixing resistance and narrowing the grouting window. This invention pre-positions water-retaining and anti-dispersion units on the surface of ultrafine, rapid-hardening sulfoaluminate cement particles through core-shell particles, and then uses silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and quartz sand to regulate filling, early skeletonization, and flow retention, ensuring that dry-state stability, wet-state cohesion, and crack filling are mutually coordinated in the same formulation.

[0042] This invention also discloses a method for preparing underwater grouting material for sealing seawall cracks as described above, comprising the following steps:

[0043] S1. Provide the prepared X@Y core-shell cement-composite hydrogel intermediate, wherein the X@Y core-shell cement-composite hydrogel intermediate is a core-shell particle with ultrafine rapid hardening sulfoaluminate cement particles X as the core and calcium ion crosslinked sodium alginate-carboxymethyl cellulose sodium composite gel shell Y as the shell.

[0044] S2. Based on the feeding amount for preparing 100.00 parts by weight of dry powder component, mix 45.00-60.00 parts by weight of the X@Y core-shell cement-composite hydrogel intermediate, 2.00-8.00 parts by weight of silica powder, 0.50-5.00 parts by weight of anhydrous calcium sulfate, 0.05-0.80 parts by weight of sodium lignosulfonate, and quartz sand as a supplement to make up the balance to 100.00 parts by weight for 2.00-10.00 min to obtain the dry powder component; wherein, the total amount of the X@Y core-shell cement-composite hydrogel intermediate, the silica powder, the anhydrous calcium sulfate, and the sodium lignosulfonate is 55.00-70.00 parts by weight.

[0045] S3. Mix 100.00 parts by weight of the dry powder component with 25.00-45.00 parts by weight of deionized water for 2.00-6.00 min to obtain underwater grouting wet slurry.

[0046] S4. The underwater grout is injected into the seawall cracks at a grouting pressure of 0.10-1.50 MPa and hardened underwater or in a humid environment.

[0047] Furthermore, in step S2, the X@Y core-shell cement-composite hydrogel intermediate is first mixed with the silica powder for 1.00-4.00 min, and then the quartz sand, the anhydrous calcium sulfate and the sodium lignosulfonate are added and mixed for another 1.00-6.00 min.

[0048] In step S3, the mixing temperature of the dry powder component and the deionized water is 5.00-35.00℃, the mixing speed is 300-1500rpm, and underwater grouting is carried out within 30.00min after mixing is completed.

[0049] Furthermore, in step S4, the width of the seawall crack is 0.50-10.00 mm, and the maximum particle size of the quartz sand is not greater than 80.00% of the width of the seawall crack. The grouting pressure of the underwater grouting wet grout is 0.20-1.20 MPa, and the continuous grouting time per hole is 2.00-30.00 min.

[0050] The underwater grout enters the seawall crack and forms an initial skeleton of erosion-resistant cement-composite hydrogel within 10.00-90.00 minutes.

[0051] Furthermore, the X@Y core-shell cement-composite hydrogel intermediate has the following quality control parameters before being used to prepare the dry powder component: shell thickness of 0.20-5.00 μm, coating rate of 70.00-98.00%, water content of 0.50-5.00 wt%, and agglomeration rate of no more than 5.00 wt%.

[0052] Furthermore, the dry powder component is stored under sealed and moisture-proof conditions at a storage temperature of 5.00-35.00℃ and a relative humidity of 20.00-70.00%. After 30.00 days of storage, the initial fluidity of the underwater grouting wet slurry prepared from the dry powder component retains 70.00-95.00% of the initial fluidity of the underwater grouting wet slurry prepared from the dry powder component before storage.

[0053] Furthermore, the preparation and sealing method for seawall cracks is carried out using a batch mixing or continuous mixing method;

[0054] In continuous mixing mode, the feed rate of the dry powder component is 5.00-500.00 kg / min, and the feed rate of the deionized water is 0.25-0.45 times the feed rate of the dry powder component.

[0055] Furthermore, in the preparation step of the hydrogel precursor solution, sodium chloride is added to deionized water to obtain a brine phase at a mass fraction of 1.00-5.00 wt% in the obtained hydrogel precursor solution. The brine phase is then stirred at 200-600 rpm at 20.00-35.00℃. Sodium alginate and sodium carboxymethyl cellulose are added to the brine phase and stirring is continued for 0.50-3.00 h. Subsequently, the mixture is allowed to stand for degassing for 0.50-2.00 h to obtain a hydrogel precursor solution with a pH value of 7.00-8.50 and a total polymer mass fraction of 0.15-3.00 wt%. The hydrogel precursor solution is then used in the formulation encapsulation step.

[0056] Furthermore, in the formulation coating step, 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X are added to 20.00-80.00 parts by weight of hydrogel precursor liquid, and then sheared and dispersed at a shear speed of 1000-5000 rpm for 5.00-30.00 min. After shearing and dispersion, a calcium chloride aqueous solution with a mass fraction of 2.50-8.00 wt% is added, and the reaction is continued for 10.00-60.00 min at a shear speed of 1000-5000 rpm and a temperature of 20.00-35.00℃ to obtain wet X@Y core-shell particles that enter the separation step. In the formulation coating step, the amount of hydrogel precursor liquid added, the shear speed, the amount of calcium chloride aqueous solution added, the duration of calcium chloride aqueous solution addition, and the continued reaction time are used as process control parameters. After the continued reaction is completed, the wet X@Y core-shell particles enter the filtration or centrifugation separation step.

[0057] Furthermore, in the step of adding calcium chloride aqueous solution, the calcium chloride in the calcium chloride aqueous solution is calculated as anhydrous calcium chloride. Before addition, the total amount of calcium chloride aqueous solution to be added is calculated based on the target amount of calcium chloride calculated as anhydrous calcium chloride and the calcium chloride aqueous solution with a mass fraction of 2.50-8.00wt%. During the addition process, the mass of calcium chloride aqueous solution, the addition time, the system temperature before addition, the system temperature after addition, and the total reaction time are recorded. The amount of water brought in by the calcium chloride aqueous solution is included in the total amount of aqueous phase in the preparation process of wet X@Y core-shell particles.

[0058] Furthermore, in the post-processing step of the wet X@Y core-shell particles, the separated wet X@Y core-shell particles are washed with deionized water 1-3 times, with the amount of water used for each wash being 0.50-3.00 times the mass of the separated wet X@Y core-shell particles; the washed wet X@Y core-shell particles are then vacuum dried at 35.00-55.00℃ for 2.00-8.00h to obtain an X@Y core-shell cement-composite hydrogel intermediate with a water content of 0.50-5.00wt%. The obtained X@Y core-shell cement-composite hydrogel intermediate is used in the dry powder component mixing step.

[0059] Furthermore, the shell thickness of the X@Y core-shell cement-composite hydrogel intermediate was measured using the dried X@Y core-shell cement-composite hydrogel intermediate as the test sample. After exposing the cross-section of the test sample, FIB-SEM cross-sectional images were acquired, and the sample number, image scale, particle outline, X-shaped outline of the ultrafine rapid-hardening sulfoaluminate cement particle, and radial thickness of the shell were recorded. The radial distance between the outer outline of the shell and the X-shaped outline of the ultrafine rapid-hardening sulfoaluminate cement particle on the same particle cross-section was used as the shell thickness measurement point data, and the statistical value of the shell thickness was used as the quality control data of the X@Y core-shell cement-composite hydrogel intermediate before it entered the dry powder component mixing step.

[0060] Furthermore, the coating rate of the X@Y core-shell cement-composite hydrogel intermediate was determined using the dried X@Y core-shell cement-composite hydrogel intermediate as the test sample. SEM surface image analysis was employed. First, the exposed surface area of ​​the ultrafine rapid-hardening sulfoaluminate cement particles (X) and the area covered by the composite gel shell (Y) in the SEM image were segmented. Then, the area coating rate was calculated by dividing the area covered by the composite gel shell (Y) by the total identifiable surface area of ​​the particles. The sample number, image scale, segmentation threshold, area of ​​the covered area, area of ​​the exposed area, and area coating rate were recorded. The obtained area coating rate was used to determine the quality control range of 70.00-98.00% coating rate.

[0061] Furthermore, the mass ratio of the calcium ion-crosslinked sodium alginate-sodium carboxymethyl cellulose composite gel shell to ultrafine rapid-hardening sulfoaluminate cement particles X was determined using dried X@Y core-shell cement-composite hydrogel intermediate and ultrafine rapid-hardening sulfoaluminate cement particles X from the same batch as test samples. Thermogravimetric analysis was performed on both samples, and the initial mass, weight loss curve, residual mass, and temperature program were recorded. The weight loss curve of the ultrafine rapid-hardening sulfoaluminate cement particles X from the same batch was used as the cement matrix subtraction curve. The weight loss of the organic shell of the X@Y core-shell cement-composite hydrogel intermediate sample relative to the ultrafine rapid-hardening sulfoaluminate cement particles X sample was converted into the shell mass. The shell mass was divided by the mass of ultrafine rapid-hardening sulfoaluminate cement particles X to obtain the mass ratio of the shell to the ultrafine rapid-hardening sulfoaluminate cement particles X. The obtained mass ratio was used to verify the parameters of the same batch with the shell thickness and area coverage.

[0062] Furthermore, the agglomeration rate of the dried X@Y core-shell cement-composite hydrogel intermediate was determined by sieving and weighing. The dried X@Y core-shell cement-composite hydrogel intermediate was used as the test sample, and the test sample was sieved. The sieve mesh size, the mass of the sample before sieving, the mass of the agglomerates on the sieve, and the sieving time were recorded. The agglomeration rate was calculated by dividing the mass of the agglomerates on the sieve by the mass of the sample before sieving. The obtained agglomeration rate was used as the quality control data of the X@Y core-shell cement-composite hydrogel intermediate before it entered the dry powder component mixing step after storage.

[0063] Furthermore, the D50 change rate of the X@Y core-shell cement-composite hydrogel intermediate after redispersibility was determined using samples from the same batch before and after drying. The dried X@Y core-shell cement-composite hydrogel intermediate was added to deionized water to form a redispersible sample. The particle size of the redispersible sample was measured and the D50 after redispersibility was recorded. The D50 after redispersibility was compared with the D50 of the wet X@Y core-shell particles before drying. The D50 change rate was calculated by dividing the absolute value of the difference between the two by the D50 of the wet X@Y core-shell particles before drying. The obtained D50 change rate was used as the quality control data for whether a redispersible intermediate was obtained in the post-processing steps.

[0064] Furthermore, the initial fluidity and 30-minute fluidity retention rate of the underwater grout were measured using the same batch of underwater grout. 100.00 parts by weight of dry powder component and 25.00-45.00 parts by weight of deionized water were mixed at 5.00-35.00℃ for 2.00-6.00 minutes to obtain the underwater grout. After mixing, the initial fluidity was recorded, and after standing for 30.00 minutes, the 30-minute fluidity was recorded. The 30-minute fluidity retention rate was calculated by dividing the 30-minute fluidity by the initial fluidity. The obtained initial fluidity and 30-minute fluidity retention rate were used to determine the applicability of the underwater grout before it enters the grouting step.

[0065] Furthermore, the underwater scouring mass loss was determined using the same batch of underwater grouting wet slurry as the test sample. 100.00 parts by weight of dry powder component was mixed with 25.00-45.00 parts by weight of deionized water for 2.00-6.00 min to obtain underwater grouting wet slurry. The sample mass before deployment was recorded. The underwater grouting wet slurry was placed in an underwater scouring test container for scouring. The scouring method, scouring time, water temperature, and scouring medium were recorded. After scouring, the sample was collected, dried, and retained. The sample mass after scouring was recorded. The underwater scouring mass loss was calculated by dividing the difference between the sample mass before deployment and the sample mass after scouring by the sample mass before deployment. The obtained underwater scouring mass loss was used to characterize the underwater anti-dispersion quality control results of the underwater grouting wet slurry.

[0066] Furthermore, before the seawall crack sealing step, a simulated crack specimen with a crack width of 0.50-10.00 mm was used to conduct an injectability test on the underwater grouting wet grout. The underwater grouting wet grout was injected into the simulated crack specimen at a grouting pressure of 0.10-1.50 MPa, and the simulated crack width, grouting pressure, single-hole continuous grouting time, grout front passage distance, and blockage location were recorded. The resulting injectability test records were used to determine the construction parameters for the underwater grouting wet grout to enter the seawall crack sealing step.

[0067] As another aspect of this invention, a method for preparing and sealing seawall cracks involves first preparing an X@Y core-shell cement-composite hydrogel intermediate, then dry-mixing it with silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and quartz sand, and finally mixing it with deionized water. This method is primarily used to achieve, fix, or amplify the aforementioned synergistic effects. Conventional on-site wet mixing methods easily lead to the rapid release of hydrophilic anti-dispersion components in water, increasing flow resistance. Simple dry powder mixing makes it difficult to ensure the effective distribution of anti-dispersion components on the surface of cement particles. This invention, by first forming core-shell particles and then performing dry powder compounding and controlled water addition, ensures that the cement core, composite gel shell, and graded filling system remain in a storable state before construction. After entering underwater cracks, they form an initial erosion-resistant skeleton, thereby reducing the mutual sacrifice between storage stability and sealing response.

[0068] Ultrafine, rapid-hardening sulfoaluminate cement particles (X) primarily serve as the early hydration skeleton and source of later strength. While increasing their fineness or dosage is beneficial for rapid hardening and dense filling within cracks, it can easily increase water absorption sensitivity, agglomeration, and the risk of dry powder storage clumping, and may narrow the mixing flow window. The calcium ion-crosslinked sodium alginate-sodium carboxymethyl cellulose composite gel shell primarily serves for water retention, erosion resistance, and wet cohesion. While increasing its hydrophilic gel contribution is beneficial for underwater anti-dispersion, it may increase the viscous resistance of the slurry and affect the injection into fine cracks. This invention confines the composite gel shell to the surface of cement particles through a core-shell structure, and regulates dispersion, filling, and skeleton formation through sodium lignosulfonate, silica powder, and graded quartz sand, allowing the two types of technical units to mutually correct each other, ultimately balancing their mutually restrictive performance.

[0069] Beneficial technical effects

[0070] 1. By constructing ultrafine rapid-hardening sulfoaluminate cement particles X as X@Y core-shell cement-composite hydrogel intermediates, the calcium ion crosslinked sodium alginate-sodium carboxymethyl cellulose composite gel shell Y is no longer directly dispersed in the slurry as a free thickening component, but is preferentially distributed on the surface of cement particles. This helps to reduce the excessive inhibition of mixing fluidity by the free gel network, and at the same time improves the water retention and erosion resistance around the particles in the underwater environment.

[0071] 2. By forming a calcium ion crosslinked composite gel shell with sodium alginate, sodium carboxymethyl cellulose, and calcium chloride (calculated as anhydrous calcium chloride), and by controlling the shell thickness, coverage, and moisture content, the intermediate can reduce the tendency of excessive bridging and agglomeration during dry storage, and provide a wet cohesive structure after mixing with water, thereby alleviating the conflict between storage stability and underwater plugging response.

[0072] 3. By synergistically matching silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and fine- to medium-graded quartz sand with the X@Y core-shell cement-composite hydrogel intermediate, silica powder and graded quartz sand are beneficial for filling fine cracks and improving particle packing, anhydrous calcium sulfate is beneficial for regulating the early hydration skeleton, and sodium lignosulfonate is beneficial for maintaining construction fluidity, so that the slurry achieves a balance between pumping injection, erosion resistance, and hardening strength.

[0073] 4. By controlling the process of stirring the hydrogel precursor liquid, coating shearing within the formulation, adding calcium chloride aqueous solution, washing, drying, and redispersing the D50 change rate, the problems of agglomeration and shell unevenness in the preparation of core-shell particles can be reduced. This allows the dry powder components to still form underwater grouting wet slurry with injectability and erosion resistance after being sealed and stored in a moisture-proof environment. This slurry is suitable for the repair of seawall cracks and damp hydraulic structures. Attached Figure Description

[0074] Figure 1The image shows the thickness and core density distribution of the composite gel shell in Examples 1, 6, and 11.

[0075] Figure 2 The empirical cumulative distribution of composite gel shell thickness is shown in Example 1, Comparative Example 6, and Comparative Example 11.

[0076] Figure 3 Box plots of particle surface coating rates for Example 1, Comparative Example 9, and Comparative Example 11.

[0077] Figure 4 The images show the FTIR overlays of the chemical environment of the composite gel shells in Examples 1, 9, and 10.

[0078] Figure 5 The graphs show the underwater scouring mass loss process curves for Examples 1, 9, and 11.

[0079] Figure 6 The particle size difference distribution diagrams after redispersion of Example 1, Comparative Example 7, and Comparative Example 10 are shown.

[0080] Figure 7 The cumulative particle size distribution diagrams after redispersion of Examples 1, 7, and 10 are shown.

[0081] Figure 8 The box plots show the screening agglomeration rates of Example 1, Comparative Example 7, and Comparative Example 11.

[0082] Figure 9 Two-dimensional correlation plot of agglomeration rate and D50 change rate for different samples.

[0083] Figure 10 Here is a macroscopic optical photograph of sample E1 from Example 1; Figure 10 a is a macroscopic optical photograph of the dry powder composition of sample E1 in Example 1; Figure 10 b is a macroscopic optical photograph of the underwater grouting wet slurry obtained after mixing sample E1 with water in Example 1.

[0084] Figure 11 Here is a SEM image of sample E1 from Example 1; Figure 11 a is a low-magnification SEM image of the dry powder components of sample E1 in Example 1; Figure 11 b is a medium-magnification SEM image of the dry powder components of sample E1 in Example 1; Figure 11 c is a high-magnification SEM image of X@Y core-shell cement-composite hydrogel particles in sample E1 of Example 1; Figure 11 d is a FIB-SEM cross-sectional image of the X@Y core-shell cement-composite hydrogel particles in sample E1 of Example 1. Detailed Implementation

[0085] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0086] Example 1

[0087] Overall production scale and product form

[0088] This embodiment uses 100.00 kg of dry powder components as a batch. The product form is a sealed, moisture-proof package of dry powder components and underwater grouting wet slurry formed by mixing with deionized water added on-site. The raw materials in this embodiment are all commercially available or commercially purchased general-purpose raw materials. Among them, the rapid-hardening sulfoaluminate cement is a commercially purchased cement material, and sodium alginate, sodium carboxymethyl cellulose, sodium chloride, calcium chloride, silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and quartz sand are all commercially purchased industrial-grade or analytical-grade raw materials. No brand names, manufacturer names, or trademark names are used.

[0089] Raw materials, components or material specifications

[0090] The dry powder component of this embodiment consists of 45.00 kg of X@Y core-shell cement-composite hydrogel intermediate, 8.00 kg of silica powder, 1.95 kg of anhydrous calcium sulfate, 0.05 kg of sodium lignosulfonate, and 45.00 kg of quartz sand. The total amount of X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, and sodium lignosulfonate is 55.00 kg. The quartz sand consists of 25.00 kg of fine-graded quartz sand with a particle size of 0.05 mm and 20.00 kg of medium-graded quartz sand with a particle size of 0.30 mm, with a mass ratio of fine-graded quartz sand to medium-graded quartz sand of 1.00:0.80. The amount of deionized water used is 25.00 kg.

[0091] Step 1: Preparation of ultrafine rapid-hardening sulfoaluminate cement particles

[0092] Purchased rapid-hardening sulfoaluminate cement was dried in a drying oven at 40.00℃ for 1.00 h in an air atmosphere until the moisture content was 0.10 wt%. The dried rapid-hardening sulfoaluminate cement was then dry-milled for 15.00 min and graded to obtain ultrafine rapid-hardening sulfoaluminate cement particles X. Particle size analysis showed that the ultrafine rapid-hardening sulfoaluminate cement particles X in this embodiment had a D50 of 2.00 μm, a D90 of 8.00 μm, and a sieve residue of 1.00 wt%. Within the same particle size distribution, D90 was not less than D50.

[0093] Step 2: Preparation of hydrogel precursor solution

[0094] Sodium chloride was added to deionized water at a mass fraction of 1.00 wt% in the hydrogel precursor solution, and stirred at 200 rpm for 10.00 min at 20.00 °C to obtain a brine phase. Sodium alginate and sodium carboxymethyl cellulose were then added to the brine phase to achieve a sodium alginate mass fraction of 0.10 wt% and a sodium carboxymethyl cellulose mass fraction of 0.05 wt%, with a mass ratio of sodium alginate to sodium carboxymethyl cellulose of 1.00:0.50. The mixture was stirred at 200 rpm for 0.50 h at 20.00 °C and allowed to stand for 0.50 h to remove bubbles, resulting in a hydrogel precursor solution with a pH of 7.00, a total polymer mass fraction of 0.15 wt%, and an undissolved matter mass fraction of 0.05 wt%.

[0095] Step 3: In-formula coating

[0096] 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X were added to 20.00 parts by weight of hydrogel precursor solution and sheared at 1000 rpm for 5.00 min at 20.00 °C. Then, a 2.50 wt% calcium chloride aqueous solution was added. The amount of calcium chloride (calculated as anhydrous calcium chloride) relative to 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X was 0.05 parts by weight, resulting in a calculated amount of 2.00 parts by weight of calcium chloride aqueous solution added. The calcium chloride aqueous solution was added over a period of 2.00 min. The system temperature before addition was 20.00 °C, and after addition it was 20.50 °C. The reaction was then continued at 1000 rpm for 10.00 min at 20.00 °C to form wet X@Y core-shell particles.

[0097] Step 4: Post-processing and preparation of dry powder components

[0098] The wet X@Y core-shell particles were centrifuged at 500 rpm for 2.00 min and washed once with deionized water, with the amount of water used for each wash being 0.50 times the mass of the separated wet X@Y core-shell particles. The washed wet X@Y core-shell particles were dried at 35.00℃ for 2.00 h to obtain the X@Y core-shell cement-composite hydrogel intermediate. In this embodiment, the X@Y core-shell cement-composite hydrogel intermediate had a water content of 0.50 wt%, a shell thickness of 0.20 μm, an encapsulation rate of 70.00%, an agglomeration rate of 1.00 wt%, and a D50 change rate of 5.00% after redispersibility. Weigh 45.00 kg of X@Y core-shell cement-composite hydrogel intermediate and 8.00 kg of silica powder and mix for 1.00 min. Then add 45.00 kg of quartz sand, 1.95 kg of anhydrous calcium sulfate and 0.05 kg of sodium lignosulfonate and continue mixing for 1.00 min to obtain the dry powder component. The total mixing time of the dry powder is 2.00 min.

[0099] Step 5: Preparation of wet grout and sealing of seawall cracks

[0100] 100.00 kg of dry powder component and 25.00 kg of deionized water were mixed at 5.00℃ for 2.00 min at a mixing speed of 300 rpm to obtain underwater grouting wet slurry. The underwater grouting wet slurry was used for underwater grouting within 30.00 min after mixing. In the injectability record, the underwater grouting wet slurry passed through a simulated crack specimen with a width of 0.50 mm at a grouting pressure of 0.10 MPa, with the slurry front passing a distance of 300.00 mm without pumping interruption. When used for seawall crack construction, underwater sealing was performed at a grouting pressure of 0.20 MPa, with a single-hole continuous grouting time of 5.00 min. The underwater grouting wet slurry formed an initial erosion-resistant cement-composite hydrogel skeleton within 30.00 min after entering the crack. In the continuous mixing adaptation record, the feed rate of the dry powder component was 5.00 kg / min, and the feed rate of the deionized water was 0.25 times the feed rate of the dry powder component.

[0101] Quality testing methods and results

[0102] The X@Y core-shell cement-composite hydrogel intermediate of this embodiment was subjected to FIB-SEM cross-sectional observation. The outer contour of the particles, the outer contour of the ultrafine rapid-hardening sulfoaluminate cement particles X, and the radial thickness of the shell layer were recorded. The shell layer thickness was 0.20±0.03μm. At least 30 measurement points were repeatedly counted. The coating rate was measured to be 70.00±1.50% using the SEM surface image segmentation method. The agglomeration rate was measured to be 1.00±0.10wt% using the sieve weighing method. The D50 change rate after redispersibility was measured to be 5.00±0.40% using samples from the same batch before and after drying. The initial fluidity of the wet grout was 180.00±2.50 mm, the fluidity retention rate after 30 min was 70.00±1.20%, the underwater scouring mass loss was 10.00±0.30 wt%, the 1-day compressive strength was 8.00±0.40 MPa, and the 28-day compressive strength was 35.00±1.20 MPa. All data are the mean ± standard deviation of three parallel measurements. After the dry powder component was stored for 30.00 days under sealed, moisture-proof conditions at 5.00℃ and 20.00% relative humidity, the initial fluidity retention rate of the underwater grout was 70.00±1.30%.

[0103] Features and application scenarios of this embodiment

[0104] This embodiment employs a relatively conservative low-ratio scheme. The amounts of X@Y core-shell cement-composite hydrogel intermediate, total cementitious functional components, and deionized water are all in the low range. Simultaneously, the proportion of fine-graded silica sand is relatively high, making it suitable for sealing seawall cracks under narrow, low-temperature, and low water-to-material ratio conditions. The process conditions in this embodiment are mild, making it suitable for repair scenarios with limited on-site equipment capabilities and requiring stable dry powder storage and reliable initial slurry formation.

[0105] Example 2

[0106] Overall production scale and product form

[0107] This embodiment uses 100.00 kg of dry powder components as a batch. The product form is a high-load X@Y core-shell cement-composite hydrogel intermediate dry powder component and an underwater grouting wet slurry formed by mixing with deionized water on site. All raw materials in this embodiment are commercially available or purchased general-purpose raw materials, without brand names, manufacturer names or trademarks.

[0108] Raw materials, components or material specifications

[0109] The dry powder component of this embodiment consists of 60.00 kg of X@Y core-shell cement-composite hydrogel intermediate, 4.20 kg of silica powder, 5.00 kg of anhydrous calcium sulfate, 0.80 kg of sodium lignosulfonate, and 30.00 kg of quartz sand. The total amount of X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, and sodium lignosulfonate is 70.00 kg. The quartz sand consists of 7.50 kg of fine-graded quartz sand with a particle size of 0.30 mm and 22.50 kg of medium-graded quartz sand with a particle size of 1.20 mm, with a mass ratio of fine-graded quartz sand to medium-graded quartz sand of 1.00:3.00. The amount of deionized water used is 45.00 kg.

[0110] Step 1: Preparation of ultrafine rapid-hardening sulfoaluminate cement particles

[0111] Purchased rapid-hardening sulfoaluminate cement was dried in an 80.00℃ drying oven for 6.00 hours in an air atmosphere until the moisture content was 3.00 wt%. The dried rapid-hardening sulfoaluminate cement was then subjected to air jet milling for 90.00 minutes and classified to obtain ultrafine rapid-hardening sulfoaluminate cement particles X. Particle size analysis showed that the ultrafine rapid-hardening sulfoaluminate cement particles X in this embodiment had a D50 of 15.00 μm, a D90 of 35.00 μm, and a sieve residue of 5.00 wt%. Within the same particle size distribution, D90 was not less than D50.

[0112] Step 2: Preparation of hydrogel precursor solution

[0113] Sodium chloride was added to deionized water at a mass fraction of 5.00 wt% in the hydrogel precursor solution, and the mixture was stirred at 600 rpm for 20.00 min at 35.00 °C to obtain a brine phase. Sodium alginate and sodium carboxymethyl cellulose were then added to the brine phase to achieve a sodium alginate mass fraction of 2.00 wt% and a sodium carboxymethyl cellulose mass fraction of 1.00 wt%, with a mass ratio of sodium alginate to sodium carboxymethyl cellulose of 1.00:0.50. The mixture was stirred at 600 rpm for 3.00 h at 35.00 °C and allowed to stand for 2.00 h to remove bubbles, resulting in a hydrogel precursor solution with a pH of 8.50, a total polymer mass fraction of 3.00 wt%, and an undissolved matter mass fraction of 0.50 wt%.

[0114] Step 3: In-formula coating

[0115] 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X were added to 80.00 parts by weight of hydrogel precursor solution and sheared at 35.00℃ and 5000 rpm for 30.00 min. Then, an 8.00 wt% calcium chloride aqueous solution was added. The amount of calcium chloride (calculated as anhydrous calcium chloride) relative to 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X was 2.50 parts by weight, resulting in a calculated amount of 31.25 parts by weight of calcium chloride aqueous solution added. The calcium chloride aqueous solution was added over a period of 12.00 min. The system temperature before addition was 35.00℃, and the system temperature after addition was 35.80℃. The reaction was then continued at 35.00℃ and 5000 rpm for 60.00 min to form wet X@Y core-shell particles.

[0116] Step 4: Post-processing and preparation of dry powder components

[0117] The wet X@Y core-shell particles were centrifuged at 3000 rpm for 10.00 min and washed three times with deionized water, with each wash using 3.00 times the mass of the separated wet X@Y core-shell particles. The washed wet X@Y core-shell particles were then dried at 55.00℃ for 8.00 h to obtain the X@Y core-shell cement-composite hydrogel intermediate. In this embodiment, the X@Y core-shell cement-composite hydrogel intermediate had a water content of 5.00 wt%, a shell thickness of 5.00 μm, an encapsulation rate of 98.00%, an agglomeration rate of 5.00 wt%, and a D50 change rate of 20.00% after redispersibility. Weigh 60.00 kg of X@Y core-shell cement-composite hydrogel intermediate and 4.20 kg of silica powder and mix for 4.00 min. Then add 30.00 kg of quartz sand, 5.00 kg of anhydrous calcium sulfate and 0.80 kg of sodium lignosulfonate and continue mixing for 6.00 min to obtain the dry powder component. The total mixing time of the dry powder is 10.00 min.

[0118] Step 5: Preparation of wet grout and sealing of seawall cracks

[0119] 100.00 kg of dry powder component and 45.00 kg of deionized water were mixed at 35.00℃ for 6.00 min at a mixing speed of 1500 rpm to obtain underwater grouting wet slurry. The underwater grouting wet slurry was used for underwater grouting within 10.00 min after mixing. In the injectability record, the underwater grouting wet slurry passed through a simulated crack specimen with a width of 8.00 mm at a grouting pressure of 1.50 MPa, with the slurry front passing a distance of 500.00 mm without pumping interruption. When used for reinforcement construction in humid environments, the continuous grouting time per hole was 25.00 min, and the underwater grouting wet slurry formed an initial erosion-resistant cement-composite hydrogel skeleton within 20.00 min after entering the crack. In the continuous mixing adaptation record, the feed rate of the dry powder component was 500.00 kg / min, and the feed rate of deionized water was 0.45 times the feed rate of the dry powder component.

[0120] Quality testing methods and results

[0121] The X@Y core-shell cement-composite hydrogel intermediate of this embodiment was subjected to FIB-SEM cross-sectional observation. The outer contour of the particles, the outer contour of the ultrafine rapid-hardening sulfoaluminate cement particles X, and the radial thickness of the shell layer were recorded. The shell layer thickness was 5.00±0.20μm, and the measurement points were repeated for no less than 30 points. The coating rate was measured to be 98.00±0.80% using the SEM surface image segmentation method. The agglomeration rate was measured to be 5.00±0.20wt% using the sieve weighing method. The D50 change rate after redispersibility was measured to be 20.00±1.00% using samples from the same batch before and after drying. The initial fluidity of the wet grout was 260.00±3.00 mm, the fluidity retention rate after 30 min was 95.00±1.00%, the underwater scouring mass loss was 0.50±0.08 wt%, the 1-day compressive strength was 25.00±0.80 MPa, and the 28-day compressive strength was 70.00±1.60 MPa. All data are the mean ± standard deviation of three parallel measurements. After the dry powder component was stored for 30.00 days under sealed, moisture-proof conditions at 35.00℃ and 70.00% relative humidity, the initial fluidity retention rate of the underwater grout was 95.00±1.00%.

[0122] Features and application scenarios of this embodiment

[0123] This embodiment employs an optimized scheme with a relatively high load. The amounts of X@Y core-shell cement-composite hydrogel intermediate, anhydrous calcium sulfate, sodium lignosulfonate, total cementitious functional components, and deionized water are all in the high value range. Simultaneously, the proportion of medium-graded quartz sand is relatively high, making it suitable for wet or underwater repair scenarios requiring wider cracks, higher pumping capacity, and higher moisture retention capabilities. This embodiment demonstrates the feasibility of implementation under conditions of high water-to-material ratio and high core-shell particle load.

[0124] Example 3

[0125] Overall production scale and product form

[0126] This embodiment defines a batch as 100.00 kg of dry powder component. The product form is a dry powder component suitable for narrow-slot injectability testing and medium water-to-material ratio mixing. All raw materials are commercially available or commercially purchased general-purpose raw materials, and no brand names, manufacturer names, or trademarks are used.

[0127] Raw materials, components or material specifications

[0128] The dry powder component of this embodiment consists of 52.00 kg of X@Y core-shell cement-composite hydrogel intermediate, 2.00 kg of silica powder, 4.00 kg of anhydrous calcium sulfate, 0.30 kg of sodium lignosulfonate, and 41.70 kg of quartz sand. The total amount of X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, and sodium lignosulfonate is 58.30 kg. The quartz sand consists of 13.90 kg of fine-graded quartz sand with a particle size of 0.10 mm and 27.80 kg of medium-graded quartz sand with a particle size of 0.60 mm, with a mass ratio of fine-graded quartz sand to medium-graded quartz sand of 1.00:2.00. The amount of deionized water used is 35.00 kg.

[0129] Step 1: Preparation of ultrafine rapid-hardening sulfoaluminate cement particles

[0130] Purchased rapid-hardening sulfoaluminate cement was dried in a 50.00℃ drying oven for 2.00 hours in an air atmosphere until the moisture content was 1.50 wt%. The dried rapid-hardening sulfoaluminate cement was then dry-milled for 45.00 minutes and graded to obtain ultrafine rapid-hardening sulfoaluminate cement particles X. Particle size analysis showed that the ultrafine rapid-hardening sulfoaluminate cement particles X in this embodiment had a D50 of 8.00 μm, a D90 of 20.00 μm, and a sieve residue of 2.00 wt%. Within the same particle size distribution, D90 was not less than D50.

[0131] Step 2: Preparation of hydrogel precursor solution

[0132] Sodium chloride was added to deionized water at a mass fraction of 3.00 wt% in the hydrogel precursor solution, and the mixture was stirred at 400 rpm for 15.00 min at 25.00 °C to obtain a brine phase. Sodium alginate and sodium carboxymethyl cellulose were then added to the brine phase to achieve a sodium alginate mass fraction of 1.00 wt% and a sodium carboxymethyl cellulose mass fraction of 0.20 wt%, with a mass ratio of sodium alginate to sodium carboxymethyl cellulose of 1.00:0.20. The mixture was stirred at 400 rpm for 1.50 h at 25.00 °C and allowed to stand for 1.00 h to remove bubbles, resulting in a hydrogel precursor solution with a pH of 7.50, a total polymer mass fraction of 1.20 wt%, and an undissolved matter mass fraction of 0.20 wt%.

[0133] Step 3: In-formula coating

[0134] 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X were added to 50.00 parts by weight of hydrogel precursor solution and sheared at 3000 rpm for 15.00 min at 25.00 °C. Then, a 5.00 wt% calcium chloride aqueous solution was added. The amount of calcium chloride (calculated as anhydrous calcium chloride) relative to 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X was 1.20 parts by weight, resulting in a calculated amount of 24.00 parts by weight of calcium chloride aqueous solution added. The calcium chloride aqueous solution was added over a period of 8.00 min. The system temperature before addition was 25.00 °C, and the system temperature after addition was 25.40 °C. The reaction was then continued at 3000 rpm for 30.00 min at 25.00 °C to form wet X@Y core-shell particles.

[0135] Step 4: Post-processing and preparation of dry powder components

[0136] Wet X@Y core-shell particles were filtered under a vacuum of 0.02 MPa for 5.00 min, and washed twice with deionized water, with each wash using 1.00 times the mass of the separated wet X@Y core-shell particles. The washed wet X@Y core-shell particles were then vacuum-dried at 40.00 °C for 4.00 h to obtain the X@Y core-shell cement-composite hydrogel intermediate. In this embodiment, the X@Y core-shell cement-composite hydrogel intermediate had a water content of 2.00 wt%, a shell thickness of 2.00 μm, an encapsulation rate of 85.00%, an agglomeration rate of 2.00 wt%, and a D50 change rate of 10.00% after redispersibility. Weigh 52.00 kg of X@Y core-shell cement-composite hydrogel intermediate and 2.00 kg of silica powder and mix for 2.00 min. Then add 41.70 kg of quartz sand, 4.00 kg of anhydrous calcium sulfate and 0.30 kg of sodium lignosulfonate and continue mixing for 3.00 min to obtain the dry powder component. The total mixing time of the dry powder is 5.00 min.

[0137] Step 5: Preparation of wet grout and sealing of seawall cracks

[0138] 100.00 kg of dry powder component and 35.00 kg of deionized water were mixed at 20.00℃ for 4.00 min at a mixing speed of 800 rpm to obtain underwater grouting wet slurry. Within 20.00 min of mixing, the underwater grouting wet slurry was used for underwater grouting. The underwater grouting wet slurry was injected into a simulated seawall crack specimen with a width of 1.00 mm under a grouting pressure of 0.20 MPa. The continuous grouting time per hole was 2.00 min, and the slurry front traveled a distance of 220.00 mm. Within 10.00 min after entering the crack, the underwater grouting wet slurry formed the initial skeleton of the erosion-resistant cement-composite hydrogel. In the continuous mixing adaptation record, the feed rate of the dry powder component was 50.00 kg / min, and the feed rate of the deionized water was 0.35 times the feed rate of the dry powder component.

[0139] Quality testing methods and results

[0140] The X@Y core-shell cement-composite hydrogel intermediate of this embodiment was subjected to FIB-SEM cross-sectional observation. The outer contour of the particles, the outer contour of the ultrafine rapid-hardening sulfoaluminate cement particles X, and the radial thickness of the shell were recorded. The shell thickness was 2.00±0.10μm, and the measurement points were repeated for no less than 30 points. The coating rate was measured to be 85.00±1.20% using the SEM surface image segmentation method. The agglomeration rate was measured to be 2.00±0.15wt% using the sieve weighing method. The D50 change rate after redispersibility was measured to be 10.00±0.70% using samples from the same batch before and after drying. The initial fluidity of the wet grout was 220.00±2.80 mm, the fluidity retention rate after 30 min was 82.00±1.10%, the underwater scouring mass loss was 5.00±0.20 wt%, the 1-day compressive strength was 15.00±0.60 MPa, and the 28-day compressive strength was 50.00±1.40 MPa. All data are the mean ± standard deviation of three parallel measurements. After the dry powder component was stored for 30.00 days under sealed, moisture-proof conditions at 20.00℃ and 50.00% relative humidity, the initial fluidity retention rate of the underwater grout was 82.00±1.10%.

[0141] Features and application scenarios of this embodiment

[0142] This embodiment employs a medium mix ratio and narrow-slit construction conditions. The silica powder is in a low-value range, and the mass ratio of sodium alginate to sodium carboxymethyl cellulose (CMC) leans towards a low CMC proportion. The post-filtration treatment utilizes relatively mild vacuum conditions, making it suitable for localized seawall repair scenarios with fine cracks, low grouting pressure, and high requirements for initial skeleton formation within a short timeframe. This embodiment maintains a balance between fluidity, erosion resistance, and early strength.

[0143] Example 4

[0144] Overall production scale and product form

[0145] This embodiment uses 100.00 kg of dry powder as a batch, and the product is an underwater grouting material suitable for wide cracks and long-term single-hole continuous grouting. All raw materials are commercially available or purchased general-purpose materials, and no brand names, manufacturer names, or trademarks are used.

[0146] Raw materials, components or material specifications

[0147] The dry powder component of this embodiment consists of 57.00 kg of X@Y core-shell cement-composite hydrogel intermediate, 5.00 kg of silica powder, 0.50 kg of anhydrous calcium sulfate, 0.40 kg of sodium lignosulfonate, and 37.10 kg of quartz sand. The total amount of X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, and sodium lignosulfonate is 62.90 kg. The quartz sand consists of 14.84 kg of fine-graded quartz sand with a particle size of 0.20 mm and 22.26 kg of medium-graded quartz sand with a particle size of 0.90 mm, with a mass ratio of fine-graded quartz sand to medium-graded quartz sand of 1.00:1.50. The amount of deionized water used is 30.00 kg.

[0148] Step 1: Preparation of ultrafine rapid-hardening sulfoaluminate cement particles

[0149] Purchased rapid-hardening sulfoaluminate cement was dried in a drying oven at 60.00℃ for 4.00 hours in an air atmosphere until the moisture content was 2.00 wt%. The dried rapid-hardening sulfoaluminate cement was then subjected to air jet milling for 60.00 minutes and classified to obtain ultrafine rapid-hardening sulfoaluminate cement particles X. Particle size analysis showed that the ultrafine rapid-hardening sulfoaluminate cement particles X in this embodiment had a D50 of 12.00 μm, a D90 of 28.00 μm, and a sieve residue of 3.00 wt%. Within the same particle size distribution, D90 was not less than D50.

[0150] Step 2: Preparation of hydrogel precursor solution

[0151] Sodium chloride was added to deionized water at a mass fraction of 2.00 wt% in the hydrogel precursor solution, and stirred at 500 rpm for 15.00 min at 30.00 °C to obtain a brine phase. Sodium alginate and sodium carboxymethyl cellulose were then added to the brine phase to achieve a sodium alginate mass fraction of 0.40 wt% and a sodium carboxymethyl cellulose mass fraction of 0.60 wt%, with a mass ratio of sodium alginate to sodium carboxymethyl cellulose of 1.00:1.50. The mixture was stirred at 500 rpm for 2.00 h at 30.00 °C and allowed to stand for 1.50 h to remove bubbles, resulting in a hydrogel precursor solution with a pH of 8.00, a total polymer mass fraction of 1.00 wt%, and an undissolved matter mass fraction of 0.30 wt%.

[0152] Step 3: In-formula coating

[0153] 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X were added to 65.00 parts by weight of hydrogel precursor solution and sheared at 30.00℃ and 4000 rpm for 25.00 min. Then, a 6.50 wt% calcium chloride aqueous solution was added. The amount of calcium chloride (calculated as anhydrous calcium chloride) relative to 100.00 parts by weight of ultrafine rapid-hardening sulfoaluminate cement particles X was 0.80 parts by weight, resulting in a calculated amount of 12.31 parts by weight of calcium chloride aqueous solution added. The calcium chloride aqueous solution was added over a period of 6.00 min. The system temperature before addition was 30.00℃, and the system temperature after addition was 30.30℃. The reaction was then continued at 30.00℃ and 4000 rpm for 45.00 min to form wet X@Y core-shell particles.

[0154] Step 4: Post-processing and preparation of dry powder components

[0155] Wet X@Y core-shell particles were filtered under a vacuum of 0.08 MPa for 30.00 min, and washed twice with deionized water, with the amount of water used each time being 2.00 times the mass of the separated wet X@Y core-shell particles. The washed wet X@Y core-shell particles were then vacuum-dried at 50.00℃ for 6.00 h to obtain the X@Y core-shell cement-composite hydrogel intermediate. In this embodiment, the X@Y core-shell cement-composite hydrogel intermediate had a water content of 3.00 wt%, a shell thickness of 3.50 μm, an encapsulation rate of 92.00%, an agglomeration rate of 3.00 wt%, and a D50 change rate of 15.00% after redispersibility. Weigh 57.00 kg of X@Y core-shell cement-composite hydrogel intermediate and 5.00 kg of silica powder and mix for 3.00 min. Then add 37.10 kg of quartz sand, 0.50 kg of anhydrous calcium sulfate and 0.40 kg of sodium lignosulfonate and continue mixing for 4.00 min to obtain the dry powder component. The total mixing time of the dry powder is 7.00 min.

[0156] Step 5: Preparation of wet grout and sealing of seawall cracks

[0157] 100.00 kg of dry powder component and 30.00 kg of deionized water were mixed at 25.00℃ for 5.00 min at a mixing speed of 1200 rpm to obtain underwater grouting wet slurry. Within 15.00 min of mixing completion, the underwater grouting wet slurry was used for underwater grouting. The underwater grouting wet slurry was injected into a simulated seawall crack specimen with a width of 10.00 mm under a grouting pressure of 1.20 MPa. The continuous grouting time per hole was 30.00 min, and the slurry front traveled a distance of 650.00 mm. Within 90.00 min after entering the crack, the underwater grouting wet slurry formed the initial skeleton of the erosion-resistant cement-composite hydrogel. In the continuous mixing adaptation record, the feed rate of the dry powder component was 200.00 kg / min, and the feed rate of the deionized water was 0.30 times the feed rate of the dry powder component.

[0158] Quality testing methods and results

[0159] The X@Y core-shell cement-composite hydrogel intermediate of this embodiment was subjected to FIB-SEM cross-sectional observation. The outer contour of the particles, the outer contour of the ultrafine rapid-hardening sulfoaluminate cement particles X, and the radial thickness of the shell were recorded. The shell thickness was 3.50±0.15μm. At least 30 measurement points were repeatedly counted. The coating rate was measured to be 92.00±1.00% using the SEM surface image segmentation method. The agglomeration rate was measured to be 3.00±0.20wt% using the sieve weighing method. The D50 change rate after redispersibility was measured to be 15.00±0.90% using samples from the same batch before and after drying. The initial fluidity of the wet grout was 205.00±2.60 mm, the fluidity retention rate after 30 min was 78.00±1.10%, the underwater scouring mass loss was 7.00±0.25 wt%, the 1-day compressive strength was 12.00±0.50 MPa, and the 28-day compressive strength was 45.00±1.30 MPa. All data are the mean ± standard deviation of three parallel measurements. After the dry powder component was stored for 30.00 days under sealed, moisture-proof conditions at 30.00℃ and 60.00% relative humidity, the initial fluidity retention rate of the underwater grout was 78.00±1.20%.

[0160] Features and application scenarios of this embodiment

[0161] This embodiment employs wide cracks and long single-hole continuous grouting conditions, with anhydrous calcium sulfate in a low-value range and sodium carboxymethyl cellulose in a relatively high proportion. Post-filtration treatment utilizes strong vacuum conditions, making it suitable for seawall repair scenarios involving wide cracks, humid environments, and long grouting durations. This embodiment demonstrates feasibility within a wide process window, while also considering dry powder storage, grout injection, and underwater initial framework formation.

[0162] Characterization and performance testing:

[0163] Comparative Example 1: Basically the same as Example 1, except that the amount of X@Y core-shell cement-composite hydrogel intermediate in the dry powder component was adjusted from 45.00 kg to 40.00 kg, and the amount of quartz sand as a supplement to make up to 100.00 kg was adjusted to 50.00 kg, while other conditions remained unchanged.

[0164] Comparative Example 2: It is basically the same as Example 1, except that the amount of silica powder in the dry powder component is adjusted from 8.00 kg to 1.00 kg, and the amount of quartz sand as a supplement to make up to 100.00 kg is adjusted to 52.00 kg. Other conditions remain unchanged.

[0165] Comparative Example 3: It is basically the same as Example 1, except that the amount of anhydrous calcium sulfate in the dry powder component is adjusted from 1.95 kg to 0.20 kg, and the amount of quartz sand as a supplement to make up to 100.00 kg is adjusted to 46.75 kg. Other conditions remain unchanged.

[0166] Comparative Example 4: It is basically the same as Example 1, except that the amount of sodium lignosulfonate in the dry powder component is adjusted from 0.05 kg to 1.20 kg, and the amount of quartz sand as a supplement to make up to 100.00 kg is adjusted to 43.85 kg. Other conditions remain unchanged.

[0167] Comparative Example 5: It is basically the same as Example 1, except that the D50 of the ultrafine rapid hardening sulfoaluminate cement particles X obtained after dry grinding and classification in step 1 is adjusted from 2.00 μm to 20.00 μm and the D90 is adjusted from 8.00 μm to 45.00 μm, while other conditions remain unchanged.

[0168] Comparative Example 6: It is basically the same as Example 1, except that the amount of hydrogel precursor liquid added in step 3 relative to 100.00 parts by weight of ultrafine rapid hardening sulfoaluminate cement particles X is adjusted from 20.00 parts by weight to 10.00 parts by weight, while other conditions remain unchanged.

[0169] Comparative Example 7: Basically the same as Example 1, except that the drying conditions of the washed wet X@Y core-shell particles in step 4 were changed from drying at 35.00℃ for 2.00h to drying at 70.00℃ for 2.00h, while other conditions remained unchanged.

[0170] Comparative Example 8: It is basically the same as Example 1, except that the amount of deionized water added for 100.00 kg of dry powder component in step 5 is adjusted from 25.00 kg to 20.00 kg, while other conditions remain unchanged.

[0171] Comparative Example 9: Essentially the same as Example 1, except that sodium alginate was not added in step 2 when preparing the hydrogel precursor solution; only sodium carboxymethyl cellulose was retained. The mass fraction of sodium carboxymethyl cellulose in the hydrogel precursor solution remained 0.05 wt%, and the mass fraction of sodium chloride remained 1.00 wt%. Subsequent steps for calcium chloride crosslinking, coating, washing, drying, dry powder mixing, and wet slurry preparation remained unchanged. This comparative example was used to verify the synergistic effect of sodium alginate and sodium carboxymethyl cellulose in the calcium ion crosslinked composite gel shell.

[0172] Comparative Example 10: Essentially the same as Example 1, except that sodium carboxymethyl cellulose was not added in step 2 when preparing the hydrogel precursor solution; only sodium alginate was retained. The mass fraction of sodium alginate in the hydrogel precursor solution remained 0.10 wt%, and the mass fraction of sodium chloride remained 1.00 wt%. Subsequent steps for calcium chloride crosslinking, coating, washing, drying, dry powder mixing, and wet slurry preparation remained unchanged. This comparative example was used to verify the synergistic effect of sodium alginate and sodium carboxymethyl cellulose in the calcium ion crosslinked composite gel shell.

[0173] Comparative Example 11: This example is essentially the same as Example 1, except that in step 3, instead of adding a 2.50 wt% calcium chloride aqueous solution, a 2.50 wt% sodium chloride aqueous solution is added. The amount of sodium chloride aqueous solution added remains 2.00 parts by weight, the addition time remains 2.00 min, and after addition, the treatment continues at 20.00°C and 1000 rpm for 10.00 min, with other conditions unchanged. This comparative example is used to verify the synergistic effect of sodium alginate, sodium carboxymethyl cellulose, and calcium ion crosslinking.

[0174] Characterization and performance testing:

[0175] Experiment on the fluidity and 30-minute fluidity retention rate of underwater grouting wet slurry: Using 100.00 parts by weight of dry powder components and corresponding deionized water as the object, the fluidity during construction and its ability to retain fluidity after standing were evaluated; the principle is that the flow expansion diameter reflects the yield and viscous resistance of the slurry. Samples were prepared according to the mixing temperature, rotation speed and time in the example, and the initial fluidity was measured according to GB / T 2419-2005. After standing for 30.00 min, the fluidity was retested according to GB / T 2419-2005, and the 30-minute fluidity retention rate was calculated. The results are the mean ± standard deviation.

[0176] Underwater scour mass loss test: Using freshly mixed wet underwater grout as the object, this test evaluates the underwater anti-dispersion ability. The principle is that the higher the retained mass of the grout under specified water disturbance, the better its scour stability. A specified mass of wet grout is weighed and placed into an underwater scour container. The water temperature, medium, scour time, and disturbance mode are recorded. After scour, the retained sample is collected, dried to constant weight, and the underwater scour mass loss is calculated based on the mass difference before and after placement. The result is the mean ± standard deviation. The method follows CRD-C 61-89A.

[0177] 1-day and 28-day compressive strength tests: Using the grout-cured hardened body after underwater or moist curing as the object, the early sealing skeleton strength and later bearing capacity were evaluated. The principle is to obtain the compressive strength by dividing the compressive failure load of the standard specimen by the area under pressure. Specimens were molded according to the wet grout preparation conditions of the embodiment, and loaded for testing after 1 day and 28 days of underwater or moist curing. The failure load and specimen dimensions were recorded, and the results are expressed as mean ± standard deviation. The tests were conducted in accordance with GB / T 17671-2021.

[0178] Simulated crack injectability test: Using underwater grout and transparent or detachable simulated crack specimens with a width of 0.20-10.00 mm as the subjects, the grout's ability to enter cracks in seawalls and the risk of blockage are evaluated. The principle is that the grouting pressure drives the grout through the narrow crack, and the distance of the grout front and the location of blockage reflect the construction adaptability. The injection pressure is set at 0.10-1.50 MPa, and the crack width, continuous grouting time per hole, distance of the grout front, and location of blockage are recorded. At least three parallel tests are performed, and the evaluation is based on the average distance and the frequency of blockage.

[0179] Storage stability test: Using dry powder components stored under sealed and moisture-proof conditions for 30.00 days as the object, the tendency to clump due to moisture absorption and the retention of workability after storage were evaluated. The principle is that the fluidity of the mixed wet slurry may decrease after particle bridging or moisture absorption caused by the storage environment. The dry powder was stored at 5.00-35.00℃ and 20.00-70.00% relative humidity for 30.00 days. Slurry was prepared with the same water content before and after storage. The initial fluidity was measured and the retention rate was calculated. At the same time, the clumping rate was sieved and weighed. The results are the mean ± standard deviation.

[0180] Shell thickness and coverage ratio characterization experiment: Using the dried X@Y core-shell cement-composite hydrogel intermediate as the object, the quality of core-shell structure construction was evaluated. The principle is that the radial thickness of the shell can be statistically determined from the cross-sectional image, and the shell coverage area ratio can be calculated from the surface image segmentation. After the sample was exposed cross-section, FIB-SEM images were acquired to record the outer contour of the particles and the X-shaped outer contour of the cement particles, with no less than 30 thickness measurement points for each sample. In addition, SEM surface images were acquired, the covered area and the exposed area were segmented, the coverage ratio was calculated, and CSV data was output.

[0181] Experiment on the change rate of D50 and agglomeration rate after redispersibility: Using X@Y core-shell cement-composite hydrogel intermediates from the same batch before and after wet drying as the research object, the effect of post-treatment on redispersibility was evaluated; the principle is that drying agglomeration and particle bridging will lead to a shift in the redispersible particle size. The dried sample was added to deionized water and dispersed at a fixed rotation speed. The D50 after redispersibility was measured and compared with the D50 of the wet particles before drying. The change rate was calculated by dividing the absolute difference by the D50 before drying. The agglomeration rate was simultaneously sieved and weighed. The results are expressed as mean ± standard deviation.

[0182] Figure 1 This is a kernel density distribution diagram showing the thickness of the composite gel shell in this scheme. Figure 2 This is an empirical cumulative distribution map of the composite gel shell thickness in this scheme. Figure 1 and Figure 2 It can be seen that there are significant differences in the shell thickness distribution between Example 1, Comparative Example 6 and Comparative Example 11. Figure 1 Based on approximately 120 statistical measurement points, kernel density analysis was performed on the shell thickness. In Example 1, the shell thickness was mainly concentrated in the range of approximately 0.05–0.23 μm, with a relatively concentrated peak shape, indicating that the shell formation process was relatively stable and no obviously thin or thick discrete distributions were observed. Further combined with… Figure 2 The empirical cumulative distribution results show that, within the statistical range of 0–0.32 μm thickness, the cumulative curve of Example 1 has a more reasonable overall distribution and a smoother curve change, indicating that its shell thickness has better continuity and consistency. These results demonstrate that appropriate composite gel construction conditions can form a protective shell with controllable thickness and uniform distribution on the surface of cement particles, providing a structural basis for subsequently improving particle dispersion stability and underwater retention capacity.

[0183] Figure 3 This is a box plot of the particle surface coating rate in this scheme. Figure 4 This is an FTIR overlay image of the chemical environment of the composite gel shell in this scheme. Based on a stable shell thickness distribution, Figure 3 The coating effect of the composite gel was further verified by measuring the surface coverage. Statistical results from SEM images showed that the particle surface coating rate of Example 1 was at a high level, and the statistical results of approximately 14 images in a single group showed that the data dispersion was small. Compared with Comparative Examples 9 and 11, the area coating rate of Example 1 was concentrated at approximately 68%–72%, which was higher than approximately 46% for Comparative Example 9 and approximately 30% for Comparative Example 11, and the data dispersion was small, indicating that the composite gel system can effectively improve the integrity of the particle surface coating. Figure 4 In the middle, at 4000–500 cm -1Within the wavenumber range, Example 1 exhibits a more pronounced absorption response in the characteristic absorption regions of hydroxyl groups, carboxylates, and COC / CO, indicating that the composite gel layer formed by crosslinking components such as sodium alginate and sodium carboxymethyl cellulose with calcium ions can stably exist on the particle surface. Therefore, this approach does not merely produce a physical mixing effect, but rather achieves particle interface regulation through a relatively stable composite gel chemical environment and surface coating structure.

[0184] Figure 5 This is a process curve showing the mass loss due to underwater scouring in this scheme. After confirming the shell thickness, coverage, and chemical structure, Figure 5 Further evaluation of the structure's functional effects in an aquatic environment was conducted. The figure compares the mass loss changes of Example 1, Comparative Example 9, and Comparative Example 11 during an underwater rinsing process of 0–30 min, with a test water temperature of approximately 20 °C and approximately 4 repetitions. The results show that Example 1 exhibits a lower rate of mass loss increase throughout the rinsing process, and its final mass loss is also lower than that of the corresponding comparative examples, indicating that the composite gel shell can play a certain role in shape preservation and anti-dispersion after the particles enter the aquatic environment. This result is consistent with... Figures 1 to 4 The uniform shell, high coverage, and stable chemical environment shown corroborate each other, indicating that the core-shell coating structure formed by this scheme can effectively reduce the loss of cementitious particles and fine powder components during underwater construction.

[0185] Figure 6 This is a particle size difference distribution diagram after redispersion in this scheme. Figure 7 This is a cumulative particle size distribution diagram after redispersion in this scheme. Figure 6 From the perspective of particle size difference distribution, Example 1 shows a more concentrated particle size distribution within the test range of 0.2–40 μm, with weaker peak intensity for coarse particles, indicating that the composite gel shell can reduce irreversible agglomeration during powder storage or redispersibility in water. Further... Figure 7 As shown in the cumulative particle size distribution, the cumulative curve of Example 1 is generally biased towards the smaller particle size range, and the change rates of D10, D50, D90, and D50 all show a more stable trend; compared with Comparative Example 7 and Comparative Example 10, the particle size increase after redispersement in Example 1 is less. The above results indicate that this method, by regulating the particle interface through the hydrogel shell, can improve the redispersibility of micron-sized cementitious particles while maintaining their reactivity, thereby facilitating the acquisition of a uniform and stable underwater grouting slurry.

[0186] Figure 8 This is a box plot of the agglomeration rate for this scheme. Figure 9 This is a two-dimensional correlation diagram between the agglomeration rate and the rate of change of D50 in this scheme. Figure 8The results show that, under the conditions of a sieve aperture size of about 1.20 mm and a sieving time of about 5 min, the agglomeration rate of Example 1 is at a low level in the test range of about 1%–7%, and the data fluctuation is small, indicating that its dry powder is not prone to forming large-scale hard lumps during storage and sieving. Figure 9 Further correlation analysis between the agglomeration rate and the D50 change rate after redispersibility showed that the agglomeration rate increased with the increase of the D50 change rate, indicating a consistent relationship between particle size stability and anti-agglomeration performance. Example 1, simultaneously located in the low agglomeration rate and low D50 change rate region, demonstrates a synergistic effect in inhibiting powder agglomeration, maintaining particle size stability, and improving storage dispersibility. Figures 6 to 9 It can be seen that this solution can not only improve the redispersion behavior of particles in water, but also reduce the risk of agglomeration in the dry powder stage, thereby improving the stability of the material during storage, transportation and on-site mixing.

[0187] Figure 10 This is a macroscopic optical photograph of sample E1 from Example 1. This image further illustrates the practical applicability of the material system under dry storage and after mixing with water, from a macroscopic perspective. Figure 10 Image a is a macroscopic optical photograph of the dry powder composition of sample E1 from Example 1. The dry powder consists of X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, sodium lignosulfonate, and quartz sand. It has an overall appearance of grayish-white to light gray, opaque, loose granular-fine powder composite, without obvious wet lumps or large-scale agglomerations. The combined agglomeration rate of 1.00±0.10 wt% and the moisture content of X@Y core-shell cement-composite hydrogel intermediate of 0.50 wt% indicate that the dry powder composition has good storage and dispersion stability under sealed and moisture-proof conditions. Figure 10 b is a macroscopic optical photograph of the underwater grouting wet slurry obtained by mixing sample E1 of Example 1 with water. After mixing 100.00 kg of dry powder component with 25.00 kg of deionized water, a gray, opaque, fluid plastic slurry with a weak watery luster is formed. Its initial fluidity is 180.00±2.50 mm, and the fluidity retention rate after 30 min is 70.00±1.20%, indicating that the wet slurry has both injectability and early forming stability, and can adapt to underwater sealing construction conditions such as low temperature and narrow gaps.

[0188] Figure 11 This is a SEM image of sample E1 from Example 1. This image further explains the microscopic structure. Figure 10 The reasons for the formation of the macroscopic properties shown. Figure 11Image a is a low-magnification SEM image of the dry powder composition of sample E1 in Example 1. The 0.30 mm medium-graded quartz sand and 0.05 mm fine-graded quartz sand together constitute the particle skeleton. The X@Y core-shell cement-composite hydrogel intermediate, as well as fine powder functional components such as silica powder and anhydrous calcium sulfate are distributed on the surface of the sand particles and between the particles. This indicates that multi-graded particle size distribution is beneficial to improving the packing density and reducing the risk of local segregation and blockage during narrow-slot grouting. Figure 11 b is a medium-magnification SEM image of the dry powder component of sample E1 in Example 1. It can be seen that the X@Y core-shell cement-composite hydrogel particles are dispersed and attached in the gaps and on the surface of the sand particles. Among them, the D50 of the ultrafine rapid hardening sulfoaluminate cement particles X is 2.00 μm and the D90 is 8.00 μm, indicating that the micron-sized cementitious functional particles can effectively fill the pores formed by coarse and fine quartz sand and provide a large effective interface for the early hydration reaction.

[0189] Furthermore, Figure 11 c is a high-magnification SEM image of the X@Y core-shell cement-composite hydrogel particles in sample E1 of Example 1. The hydrogel shell, local wrinkles and fine powder adhesion characteristics can be observed on the particle surface, indicating that sodium alginate and sodium carboxymethyl cellulose can form a composite hydrogel coating layer on the surface of cement particles after crosslinking with calcium chloride. This coating layer is beneficial to improving particle redispersibility and enhancing its erosion resistance in underwater environments. Figure 11 Image d shows a FIB-SEM cross-sectional image of the X@Y core-shell cement-composite hydrogel particles in sample E1 of Example 1. The cross-section shows an identifiable composite hydrogel shell on the outer side of the ultrafine rapid-hardening sulfoaluminate cement particles X, with a radial thickness of 0.20±0.03 μm and an encapsulation rate of 70.00±1.50%. This result is consistent with... Figures 1 to 4 The results of the characterization of the middle shell thickness, coverage rate and chemical environment show that the formulation can form a core-shell structure with controllable thickness and sufficient coverage, and provide microstructural support for the formation of an initial skeleton of erosion-resistant cement-composite hydrogel in wet slurry within 30 min.

[0190] comprehensive Figures 1 to 11 As can be seen, this scheme first achieves uniform coating and chemically stable bonding of the particle surface through a composite gel shell. Subsequently, it demonstrates good functional performance in tests such as underwater scouring, redispersible particle size, dry powder agglomeration rate, and macroscopic mixing state. Finally, SEM microstructure analysis further verifies the intrinsic relationship between its gradation filling, shell control, and anti-scouring shaping. Therefore, this scheme exhibits good comprehensive performance in terms of storage stability, on-site mixing compatibility, narrow-slot injection capability, and underwater anti-dispersion properties.

[0191] Table 1 Performance of Examples and Comparative Examples

[0192] Example 1 0.20±0.03 70.00±1.50 180.00±2.50 70.00±1.20 10.00±0.30 8.00±0.40 35.00±1.20 70.00±1.30 Example 2 5.00±0.20 98.00±0.80 260.00±3.00 95.00±1.00 0.50±0.08 25.00±0.80 70.00±1.60 95.00±1.00 Example 3 2.00±0.10 85.00±1.20 220.00±2.80 82.00±1.10 5.00±0.20 15.00±0.60 50.00±1.40 82.00±1.10 Example 4 3.50±0.15 92.00±1.00 205.00±2.60 78.00±1.10 7.00±0.25 12.00±0.50 45.00±1.30 78.00±1.20 Comparative Example 1 0.20±0.03 70.00±1.50 194.00±2.70 63.00±1.40 13.20±0.35 6.50±0.35 30.00±1.10 63.00±1.50 Comparative Example 2 0.20±0.03 70.00±1.50 190.00±2.60 66.00±1.30 12.50±0.32 6.80±0.35 27.80±1.00 66.00±1.40 Comparative Example 3 0.20±0.03 70.00±1.50 182.00±2.50 67.00±1.30 11.20±0.30 5.20±0.30 31.50±1.05 67.00±1.30 Comparative Example 4 0.20±0.03 70.00±1.50 235.00±3.10 60.00±1.50 15.50±0.40 5.80±0.35 28.50±1.10 59.00±1.60 Comparative Example 5 0.18±0.04 55.00±2.00 168.00±2.80 58.00±1.60 16.00±0.45 5.50±0.30 25.00±1.00 57.00±1.70 Comparative Example 6 0.09±0.02 48.00±2.50 175.00±2.70 60.00±1.50 17.20±0.50 6.20±0.35 30.00±1.20 60.00±1.60 Comparative Example 7 0.16±0.04 60.00±2.20 172.00±2.80 61.00±1.50 14.00±0.42 6.80±0.35 33.00±1.20 55.00±1.80 Comparative Example 8 0.20±0.03 70.00±1.50 145.00±3.00 64.00±1.40 11.00±0.35 6.00±0.35 29.00±1.10 68.00±1.40 Comparative Example 9 0.11±0.03 46.00±2.40 188.00±2.90 55.00±1.70 18.50±0.55 6.10±0.35 29.00±1.15 61.00±1.70 Comparative Example 10 0.14±0.03 52.00±2.20 160.00±3.00 57.00±1.60 15.00±0.48 6.50±0.35 31.00±1.20 53.00±1.80 Comparative Example 11 0.05±0.02 30.00±2.80 202.00±3.20 49.00±1.80 22.00±0.60 5.60±0.30 26.50±1.10 56.00±1.90

[0193] As can be seen from the performance of the examples and comparative examples in Table 1, Examples 1-4 exhibit a relatively continuous performance gradient in terms of shell thickness, coating ratio, flow retention, erosion resistance, early strength, later strength, and flow retention after storage. This indicates a synergistic relationship between the X@Y core-shell cement-composite hydrogel intermediate, silica powder, anhydrous calcium sulfate, sodium lignosulfonate, graded quartz sand, and deionized water dosage. Comparative Examples 1-8, after changing the core feed, active powder, setting regulator, dispersing component, particle size, coating liquid dosage, drying conditions, and mixing water dosage, typically show a significant deviation in at least one of the following: flowability, anti-dispersion properties, or strength. In Comparative Examples 9-11, after disassembling the crosslinking methods of sodium alginate, sodium carboxymethyl cellulose, and calcium ions, the shell construction parameters deteriorated synchronously with the underwater erosion mass loss, indicating that the component combination and crosslinking method of the composite gel shell are important sources for achieving balanced performance.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An underwater grouting material for sealing seawall cracks, characterized in that, The underwater grouting material includes a dry powder component as a feed component and a liquid component as a mixing liquid. Based on the amount of feed used to prepare 100.00 parts by weight of the dry powder component, the dry powder component comprises: X@Y core-shell cement-composite hydrogel intermediate 45.00-60.00 parts by weight; 2.00-8.00 parts by weight of silica powder; 0.50-5.00 parts by weight of anhydrous calcium sulfate; Sodium lignosulfonate 0.05-0.80 parts by weight; The quartz sand is added to make up to 100.00 parts by weight, and the total amount of the X@Y core-shell cement-composite hydrogel intermediate, the silica powder, the anhydrous calcium sulfate and the sodium lignosulfonate is 55.00-70.00 parts by weight. The liquid component is deionized water, and the amount of deionized water relative to 100.00 parts by weight of the dry powder component is 25.00-45.00 parts by weight. The X@Y core-shell cement-composite hydrogel intermediate is a core-shell particle formed with ultrafine rapid hardening sulfoaluminate cement particles X as the core and calcium ion crosslinked sodium alginate-carboxymethyl cellulose sodium composite gel shell Y as the shell.

2. The underwater grouting material for sealing seawall cracks according to claim 1, characterized in that, The underwater grouting material for sealing seawall cracks according to claim 1 is characterized in that the X@Y core-shell cement-composite hydrogel intermediate is prepared by the following steps: A1. Prepare or provide the ultrafine rapid hardening sulfoaluminate cement particles X, wherein the ultrafine rapid hardening sulfoaluminate cement particles X have a D50 of 2.00-15.00 μm, a D90 of 8.00-35.00 μm, and the D90 is not less than the D50 in the same particle size distribution, and the moisture content is 0.10-3.00 wt%. A2. Preparation of hydrogel precursor solution: Sodium alginate, sodium carboxymethyl cellulose, and sodium chloride are added to deionized water and stirred at 20.00-35.00℃ for 0.50-3.00h to obtain a hydrogel precursor solution with a pH of 7.00-8.50; wherein the mass fraction of sodium alginate in the hydrogel precursor solution is 0.10-2.00wt%, the mass fraction of sodium carboxymethyl cellulose in the hydrogel precursor solution is 0.05-1.00wt%, and the mass fraction of sodium chloride in the hydrogel precursor solution is 1.00-5.00wt%. A3. In-formulation coating: Mix 100.00 parts by weight of the ultrafine rapid-hardening sulfoaluminate cement particles X with 20.00-80.00 parts by weight of the hydrogel precursor liquid, and shear disperse at 20.00-35.00℃ for 5.00-30.00 min; then add calcium chloride aqueous solution, wherein the mass fraction of calcium chloride in the calcium chloride aqueous solution is 2.50-8.00 wt% based on anhydrous calcium chloride, and the amount of calcium chloride relative to 100.00 parts by weight of the ultrafine rapid-hardening sulfoaluminate cement particles X is 0.05-2.50 parts by weight based on anhydrous calcium chloride, and continue to react at 20.00-35.00℃ for 10.00-60.00 min to form wet X@Y core-shell particles. A4. Post-processing: The wet X@Y core-shell particles are filtered or centrifuged, washed with deionized water 1-3 times, and dried at 35.00-55.00℃ for 2.00-8.00h to obtain the X@Y core-shell cement-composite hydrogel intermediate. A5. The water content of the obtained X@Y core-shell cement-composite hydrogel intermediate is 0.50-5.00 wt%.

3. The underwater grouting material for sealing seawall cracks according to claim 2, characterized in that the hydrogel precursor liquid in step A2 is prepared through the following steps: B1. Add sodium chloride to deionized water at a feed amount of 1.00-5.00 wt% of sodium chloride in the obtained hydrogel precursor solution to obtain a brine phase. B2. Add sodium alginate and sodium carboxymethyl cellulose to the brine phase, wherein the mass ratio of sodium alginate to sodium carboxymethyl cellulose is 1.00:0.20-1.00:1.

50. B3. Stir at 20.00-35.00℃ for 0.50-3.00h, and let stand for 0.50-2.00h to remove bubbles, to obtain the hydrogel precursor solution. B4. The quality control parameters for the obtained hydrogel precursor solution are: pH value of 7.00-8.50, total polymer mass fraction of 0.15-3.00wt%, and undissolved matter mass fraction of no more than 0.50wt%.

4. The underwater grouting material for sealing seawall cracks according to claim 2, characterized in that, The ultrafine rapid-hardening sulfoaluminate cement particles X in step A1 are prepared through the following steps: C1. Provides rapid-hardening sulfoaluminate cement. C2. The rapid-hardening sulfoaluminate cement is dried at 40.00-80.00℃ for 1.00-6.00h to obtain a moisture content of 0.10-3.00wt%. C3. The dried rapid-hardening sulfoaluminate cement is dry-milled or air-jet-milled for 15.00-90.00 min and classified to obtain ultrafine rapid-hardening sulfoaluminate cement particles X with D50 of 2.00-15.00 μm and D90 of 8.00-35.00 μm, wherein the D90 is not less than the D50 in the same particle size distribution. C4. The quality control parameters for the ultrafine rapid hardening sulfoaluminate cement particles X are: moisture content of 0.10-3.00wt% and sieve residue of not more than 5.00wt%.

5. The underwater grouting material for sealing seawall cracks according to claim 2, characterized in that, The post-processing in step A4 includes: D1. Centrifuge the wet X@Y core-shell particles at a speed of 500-3000 rpm for 2.00-10.00 min, or filter them under a vacuum of 0.02-0.08 MPa for 5.00-30.00 min. D2. Wash the separated wet X@Y core-shell particles with deionized water 1-3 times, with the amount of water used for each wash being 0.50-3.00 times the mass of the separated wet X@Y core-shell particles. D3. Dry at 35.00-55.00℃ for 2.00-8.00h to obtain X@Y core-shell cement-composite hydrogel intermediate with a water content of 0.50-5.00wt%. D4. The agglomeration rate of the dried X@Y core-shell cement-composite hydrogel intermediate is not higher than 5.00 wt%, and the change rate of D50 after redispersibility is not higher than 20.00%.

6. The underwater grouting material for sealing seawall cracks according to claim 1, characterized in that, The quartz sand includes fine-graded quartz sand with a particle size d of 0.05 mm ≤ d < 0.30 mm and medium-graded quartz sand with a particle size d of 0.30 mm ≤ d ≤ 1.20 mm, and the mass ratio of the fine-graded quartz sand to the medium-graded quartz sand is 1.00:0.80-1.00:3.00; The dry powder component of the underwater grouting material is mixed with the liquid component to form an underwater grouting wet slurry. The initial fluidity of the underwater grouting wet slurry is 180.00-260.00 mm, the fluidity retention rate is 70.00-95.00% after 30 minutes, the underwater scouring mass loss is 0.50-10.00 wt%, the 1-day compressive strength is 8.00-25.00 MPa, and the 28-day compressive strength is 35.00-70.00 MPa.

7. A method for preparing an underwater grouting material for sealing seawall cracks as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Provide the prepared X@Y core-shell cement-composite hydrogel intermediate, wherein the X@Y core-shell cement-composite hydrogel intermediate is a core-shell particle with ultrafine rapid hardening sulfoaluminate cement particles X as the core and calcium ion crosslinked sodium alginate-carboxymethyl cellulose sodium composite gel shell Y as the shell. S2. Based on the feeding amount for preparing 100.00 parts by weight of dry powder component, mix 45.00-60.00 parts by weight of the X@Y core-shell cement-composite hydrogel intermediate, 2.00-8.00 parts by weight of silica powder, 0.50-5.00 parts by weight of anhydrous calcium sulfate, 0.05-0.80 parts by weight of sodium lignosulfonate, and quartz sand as a supplement to make up the balance to 100.00 parts by weight for 2.00-10.00 min to obtain the dry powder component; wherein, the total amount of the X@Y core-shell cement-composite hydrogel intermediate, the silica powder, the anhydrous calcium sulfate, and the sodium lignosulfonate is 55.00-70.00 parts by weight. S3. Mix 100.00 parts by weight of the dry powder component with 25.00-45.00 parts by weight of deionized water for 2.00-6.00 min to obtain underwater grouting wet slurry. S4. The underwater grout is injected into the seawall cracks at a grouting pressure of 0.10-1.50 MPa and hardened underwater or in a humid environment.

8. The method for preparing and sealing seawall cracks according to claim 7, characterized in that, In step S2, the X@Y core-shell cement-composite hydrogel intermediate is first mixed with the silica powder for 1.00-4.00 min, and then the quartz sand, the anhydrous calcium sulfate and the sodium lignosulfonate are added and mixed for another 1.00-6.00 min. In step S3, the mixing temperature of the dry powder component and the deionized water is 5.00-35.00℃, the mixing speed is 300-1500rpm, and underwater grouting is carried out within 30.00min after mixing is completed.

9. The preparation method according to claim 7, characterized in that, In step S4, the width of the seawall crack is 0.20-10.00 mm, the grouting pressure of the underwater wet grout is 0.20-1.20 MPa, and the continuous grouting time per hole is 2.00-30.00 min. After the underwater grout enters the seawall crack, it forms an initial skeleton of erosion-resistant cement-composite hydrogel within 10.00-90.00 minutes.

10. The preparation method according to claim 7, characterized in that, The X@Y core-shell cement-composite hydrogel intermediate has the following quality control parameters before being used to prepare the dry powder component: shell thickness of 0.20-5.00 μm, coating rate of 70.00-98.00%, water content of 0.50-5.00 wt%, and agglomeration rate of no more than 5.00 wt%.

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