Underwater anti-dispersion cement-based grouting repair material and preparation method thereof

Abstract

The invention discloses an underwater anti-dispersion cement-based grouting repair material and a preparation method thereof. The grouting repair material comprises a liquid material polyurethane prepolymer and a powder material, the polyurethane prepolymer is prepared by mixing a polyol oligomer, diisocyanate, a hydrophilic chain extender and a catalyst, and the powder material comprises cement, high belite cement, a mineral admixture, aggregate, an anti-dispersing agent, an expanding agent, a water reducing agent, a powder waterproof agent, a defoaming agent and a reinforcing agent. According to the invention, the setting time of the grouting material is regulated and controlled by adjusting the type and proportion of the cement; the polyurethane prepolymer and the cement paste have a synergistic effect, and under the flowing water condition, the dispersion resistance of the slurry can be remarkably enhanced through the synergistic effect of the polyurethane prepolymer and the cement paste, and the slurry loss phenomenon is effectively reduced; the grouting repair material disclosed by the invention is applied to the repair process of hydraulic structures, and has the characteristics of realization of regulation and control of setting time within a certain range, high strength, strong bonding force of new and old interfaces, excellent dispersion resistance and the like.

Description

Technical Field

[0001] This invention relates to the technical field of cement-based grouting repair materials, specifically to an underwater anti-dispersion cement-based grouting repair material and its preparation method. Background Technology

[0002] In the field of underwater engineering construction and repair, traditional cement-based materials face significant challenges. The complexity of the underwater environment, the fluidity and pressure of water, and the various chemicals present make it difficult for ordinary cement-based grouting materials to function properly during underwater construction. When repairing underwater bridge foundations or underwater port structures, ordinary grouting materials are easily diluted and dispersed by water, and their excessively long setting time leads to material loss, failing to effectively fill defects within the structure. Therefore, it is necessary to develop an anti-dispersion repair material for underwater hydraulic structures. Anti-dispersion agents are high-molecular polymer materials. When directly incorporated into cement-based materials, their chemical structure and physical properties alter the pore structure of the cement-based materials. Some anti-dispersion agents may occupy space in the cement paste, and their presence during cement hydration may hinder the normal filling of cement hydration products.

[0003] Currently, in the field of underwater non-dispersible concrete, the commonly used flocculants are mainly polyacrylamide-based and cellulose-based. These two types of flocculants have significant drawbacks. They tend to introduce a large number of pores into the concrete, failing to effectively promote the densification of the structure during the hardening process, directly leading to a significant increase in porosity and consequently a significant reduction in material strength. Simultaneously, the addition of flocculants prolongs the concrete setting time. When encountering flowing water erosion conditions, newly poured concrete cannot quickly reach sufficient strength and is unable to effectively resist the erosive effects of water flow, potentially leading to serious consequences such as material loss or structural damage. Therefore, to address the specific needs of hydraulic structure repair work, there is an urgent need to develop an underwater anti-dispersion repair material. This material should possess characteristics such as controllable setting time within a certain range, high strength, strong adhesion between new and old interfaces, and excellent anti-dispersion performance, to effectively ensure the safety, stability, and long-term use of hydraulic structures. Summary of the Invention

[0004] To address the problems existing in the above-mentioned background technology, the present invention provides an underwater anti-dispersion cement-based grouting repair material and its preparation method. It is applied to the repair process of hydraulic structures and has the characteristics of controlling the setting time within a certain range, high strength, strong adhesion between new and old interfaces, and excellent anti-dispersion performance.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: An underwater anti-dispersion cement-based grouting repair material includes a liquid component and a powder component. The liquid component is a polyurethane prepolymer with an isocyanate index R preferably in the range of 3 to 4. The polyurethane prepolymer is prepared by mixing the following raw material components: 100-150 parts of polyol oligomers; 35-80 parts of diisocyanate; 2-5 parts of hydrophilic chain extender; 1-2 parts catalyst; The powder comprises the following components in parts by weight: 80-120 parts cement High-Belly cement (grade 62.5) 10-30 parts 5-10 parts of mineral admixtures Collect 15-20 parts, Anti-dispersant 1-1.5 parts, 1-1.5 parts of expanding agent, Water-reducing agent 0.1~0.5 parts, 0.5-1.5 parts of powder waterproofing agent, Defoamer 0.1~0.5 parts, 0.5-1.5 parts of reinforcing agent; The mass ratio of the powder to the liquid is controlled within the range of 10:1 to 3.

[0006] Furthermore, the polyol oligomers described in this invention are selected from any one or a mixture of more than one of polyoxypropylene glycol (PPG), polyoxyethylene glycol (PEG), and polytetrahydrofuran ether glycol (PTMG).

[0007] Furthermore, the diisocyanate of the present invention is selected from any one or a mixture of more than one of diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), and isophorone diisocyanate (IPDI); the isocyanate index (R) is 3 to 4.

[0008] Furthermore, the catalyst described in this invention is selected from any one or a mixture of one or more amine catalysts and organometallic catalysts.

[0009] Furthermore, the hydrophilic chain extender described in this invention is sodium 1,4-butanediol-2-sulfonate.

[0010] Furthermore, the antidispersant described in this invention is SBT. ® -NDA underwater anti-dispersion concrete admixture; Furthermore, the aggregate described in this invention is composed of three types of quartz sand with fineness of 40-80 mesh, 80-120 mesh, and 120-200 mesh, with the following mass percentages of each component: 30%-50% 40-80 mesh quartz sand, 30%-50% 80-120 mesh quartz sand, and 10%-30% 120-200 mesh quartz sand. Optimizing the aggregate gradation helps to construct a more compact particle packing structure and reduce the porosity inside the material.

[0011] The cement described in this invention is selected from any one or a mixture of two of silicate cement (grade 52.5) ​​and sulfoaluminate cement (grade 52.5).

[0012] Furthermore, the mineral admixtures of the present invention are spherical fly ash and silica fume, with a mass ratio of spherical fly ash to silica fume of 2~3:1; the spherical particles of fly ash can reduce slurry friction and improve fluidity, while the micro-filling effect of silica fume can further reduce the risk of bleeding. Within this ratio range, the advantages of both can be taken into account.

[0013] Furthermore, the water-reducing agent of the present invention is selected from any one or a mixture of TC-PC500 powder polycarboxylate water-reducing agent, TC-PC100-T powder polycarboxylate water-reducing agent and TC-PC400 powder polycarboxylate water-reducing agent.

[0014] Furthermore, the expanding agent described in this invention is selected from any one or a mixture of calcium sulfoaluminate expanding agents and calcium oxide expanding agents.

[0015] Furthermore, the powder waterproofing agent of the present invention is selected from any one or a mixture of one or more of Waterproof Agent Powder 8208, BSPOWDER D and BS POWDER B.

[0016] Furthermore, the defoamer described in this invention is selected from any one or a mixture of more than one of polysiloxane defoamers and organosilicon defoamers.

[0017] Furthermore, the reinforcing agent described in this invention is selected from either zirconium silicone or sodium metafeldtate.

[0018] Furthermore, the preparation method of the liquid polyurethane prepolymer of the present invention includes the following steps: (1) Add the measured amount of polyol oligomer to the reactor and heat it to 110~120℃ for vacuum dehydration for 1.5~2h; (2) After the water content is reduced to 0.05%, cool down to 60°C, add diisocyanate and sodium 1,4-butanediol-2-sulfonate and polymerize at 75~85°C for 2~3 hours; (3) After the reaction in step (2) is completed, cool down to 60°C, add catalyst and continue stirring for 30 minutes, then seal and discharge to obtain polyurethane prepolymer.

[0019] Furthermore, the present invention also provides a method for preparing the above-mentioned underwater anti-dispersion cement-based grouting repair material, comprising the following steps: taking each raw material according to the weight parts, mixing them evenly, and packaging them.

[0020] Furthermore, the present invention also provides a method for using an underwater anti-dispersion cement-based grouting repair material, specifically: first, the powder of the grouting material is thoroughly mixed with water, and the powder and water are mixed in a predetermined ratio to form a slurry; then, liquid polyurethane prepolymer is added to the slurry and further stirred until it is uniformly mixed, and then grouting operations can be carried out. During this process, the mass ratio of powder, water and polyurethane prepolymer is controlled within the range of 10:0.33~0.35:1~3.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The company's self-developed SBT is adopted. ® -NDA underwater anti-dispersion concrete admixture forms a special protective film on the surface of the grouting material, effectively preventing cement paste loss and aggregate dispersion during underwater pouring. It imparts good fluidity to the grouting material, allowing it to self-level and self-compact underwater. This is particularly beneficial for complex underwater structures, such as irregular holes and gaps in underwater foundations, effectively filling them and ensuring structural integrity.

[0022] (2) By adjusting the type and proportion of cement and coordinating them, the setting time of the grouting material can be effectively controlled. The setting time can be controlled within the range of 10 to 100 minutes, thus meeting the special needs of various construction environments. At the same time, the presence of high belite cement can significantly improve the long-term strength and high-temperature stability of concrete. It has excellent resistance to chemical corrosion and carbonation and is suitable for harsh environments.

[0023] (3) The polyurethane prepolymer and cement grout work synergistically to exhibit superior performance advantages. Under dynamic water conditions, the synergistic effect of the two can significantly enhance the anti-dispersion ability of the grout and effectively reduce grout loss. The polyurethane prepolymer has excellent fluidity and can easily penetrate into the capillary pores of cracks, bonding tightly with the substrate to form a strong adhesive layer. This adhesive layer has good adaptability and can cope with slight deformation, thus effectively avoiding secondary leakage problems. Moreover, the heat released during cement hydration can accelerate the polymerization reaction between polyurethane prepolymer and water. At the same time, as a high-performance gas absorber, the CO2 produced by cement during the polymerization reaction of polyurethane prepolymer and water will react chemically with the unhydrated cement particles to form calcium carbonate. This series of reactions not only accelerates the hardening speed of the grout but also greatly shortens the curing time. In addition, the reaction products can fill the pores, further improving the density and durability of concrete. Furthermore, the products formed after the polyurethane prepolymer is cured construct a continuous polymer network structure in the cement-based grouting material. This unique structure effectively improves the original rigidity of cement-based materials, significantly enhances the material's ability to resist dynamic loads, and enables it to have more reliable performance in complex and ever-changing engineering environments.

[0024] (4) The addition of powder waterproofing agent can provide long-lasting and effective waterproofing performance for grouting materials, and has the properties of inhibiting efflorescence of the substrate and enhancing the substrate's resistance to freeze-thaw cycles. In addition, if microcracks appear during later use, the active ingredients in the reinforcing agent will still exist and can be reactivated when there is water, and will continue to generate crystals to fill the cracks, playing a certain degree of self-repair role, extending the service life of the structure, and reducing maintenance costs and repair frequency. Attached Figure Description

[0025] Figure 1 The images show the appearance of the grouting repair materials prepared according to the embodiments and comparative examples of the present invention after curing, wherein (a) is Example 5, (b) is Comparative Example 1, and (c) is Comparative Example 2.

[0026] Figure 2 The following are comparisons of the underwater anti-dispersion effects of embodiments, comparative examples, and ordinary cement-based grouting materials of the present invention, wherein (a) is an ordinary cement-based grouting material, (b) is Example 5, and (c) is Comparative Example 7.

[0027] Figure 3 The waterproofing effect of the grouting repair materials prepared in Example 5 and Comparative Example 11 is shown, with Example 5 on the left and Comparative Example 11 on the right. Specific implementation methods The preferred embodiments of the present invention will now be described in more detail and completely. The embodiments provided below are only some embodiments of the present invention and not all of them. Any changes or substitutions to the materials made by those skilled in the art based on the inspiration of the present invention shall still fall within the protection scope of the present invention.

[0028] Example 1 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: Weigh each raw material according to the formula, and mix them thoroughly to obtain powder.

[0029] The liquid preparation steps are as follows: In a reactor equipped with a stirrer, nitrogen protection device, and reflux condenser, according to the isocyanate index 3, 100 parts of polyoxyethylene glycol (PEG) were added, and the mixture was heated to 110°C and vacuum dehydrated for 1.5 hours. After the water content was measured to be less than 0.05%, the mixture was cooled to 60°C, and 38 parts of diphenylmethane diisocyanate (MDI) and 2 parts of sodium 1,4-butanediol-2-sulfonate were added. The mixture was reacted at 80°C for 2 hours. After cooling to 60°C, 1 part of organotin catalyst was added, and the mixture was stirred for 30 minutes. The mixture was then sealed and discharged to obtain the polyurethane prepolymer.

[0030] The mass ratio of powder, water, and polyurethane prepolymer should be controlled within the range of 10:0.33:1. The powder and water of the grouting material should be thoroughly mixed evenly, and the powder and water should be mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer should be added to the slurry and further stirred until uniformly mixed.

[0031] Example 2 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: Weigh each raw material according to the formula, and mix them thoroughly to obtain powder.

[0032] The liquid preparation steps are as follows: In a reactor equipped with a stirrer, nitrogen protection device, and reflux condenser, according to the isocyanate index 4, 150 parts of polyoxyethylene glycol (PEG) were added, and the mixture was heated to 110°C and vacuum dehydrated for 2 hours. After the water content was measured to be below 0.05%, the mixture was cooled to 60°C, and 80 parts of dicyclohexylmethane diisocyanate (HMDI) and 5 parts of sodium 1,4-butanediol-2-sulfonate were added. The mixture was reacted at 80°C for 3 hours. After cooling to 60°C, 2 parts of organotin catalyst were added, and the mixture was stirred for 30 minutes. The mixture was then sealed and discharged to obtain the polyurethane prepolymer.

[0033] The mass ratio of powder, water, and polyurethane prepolymer should be controlled within the range of 10:0.34:2. The powder and water of the grouting material should be thoroughly mixed evenly, and the powder and water should be mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer should be added to the slurry and further stirred until uniformly mixed.

[0034] Example 3 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: Weigh each raw material according to the formula, and mix them thoroughly to obtain powder.

[0035] The liquid preparation steps are as follows: In a reactor equipped with a stirrer, nitrogen protection device, and reflux condenser, according to an isocyanate index of 3.5, 120 parts of polytetrahydrofuran ether diol (PTMG) were added, and the mixture was heated to 110°C and vacuum dehydrated for 2 hours. After the water content was measured to be below 0.05%, the mixture was cooled to 60°C, and 48 parts of isophorone diisocyanate (IPDI) and 3 parts of sodium 1,4-butanediol-2-sulfonate were added. The mixture was reacted at 80°C for 3 hours. After cooling to 60°C, 1.5 parts of organotin catalyst were added, and the mixture was stirred for 30 minutes. The mixture was then sealed and discharged to obtain the polyurethane prepolymer.

[0036] The mass ratio of powder, water, and polyurethane prepolymer should be controlled within the range of 10:0.35:3. The powder and water of the grouting material should be thoroughly mixed evenly, and the powder and water should be mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer should be added to the slurry and further stirred until uniformly mixed.

[0037] Example 4 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: Weigh each raw material according to the formula, and mix them thoroughly to obtain powder.

[0038] The liquid preparation steps are the same as those for the polyurethane prepolymer preparation in Example 2.

[0039] The mass ratio of powder, water, and polyurethane prepolymer should be controlled within the range of 10:0.33:1. The powder and water of the grouting material should be thoroughly mixed evenly, and the powder and water should be mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer should be added to the slurry and further stirred until uniformly mixed.

[0040] Example 5 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: According to the established formula, all kinds of raw materials are accurately weighed, and then the raw materials are thoroughly stirred and mixed until uniform, so as to obtain powder.

[0041] The preparation process of the liquid material is exactly the same as the preparation method of the polyurethane prepolymer in Example 2.

[0042] The mass ratio of powder, water, and polyurethane prepolymer is controlled within the range of 10:0.33:1. The powder and water of the grouting material are thoroughly mixed evenly, and the powder and water are mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer is added to the slurry, and the mixture is further stirred and mixed evenly to obtain the underwater anti-dispersion cement-based grouting repair material.

[0043] Example 6 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: According to the established formula, all kinds of raw materials are accurately weighed, and then the raw materials are thoroughly stirred and mixed until uniform, so as to obtain powder.

[0044] The preparation process of the liquid material is exactly the same as the preparation method of the polyurethane prepolymer in Example 2.

[0045] The mass ratio of powder, water, and polyurethane prepolymer is controlled within the range of 10:0.33:1. The powder and water of the grouting material are thoroughly mixed evenly, and the powder and water are mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer is added to the slurry, and the mixture is further stirred and mixed evenly to obtain the underwater anti-dispersion cement-based grouting repair material.

[0046] Example 7 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: According to the established formula, all kinds of raw materials are accurately weighed, and then the raw materials are thoroughly stirred and mixed until uniform, so as to obtain powder.

[0047] The preparation process of the liquid material is exactly the same as the preparation method of the polyurethane prepolymer in Example 2.

[0048] The mass ratio of powder, water, and polyurethane prepolymer is controlled within the range of 10:0.33:1. The powder and water of the grouting material are thoroughly mixed evenly, and the powder and water are mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer is added to the slurry, and the mixture is further stirred and mixed evenly to obtain the underwater anti-dispersion cement-based grouting repair material.

[0049] Example 8 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: According to the established formula, all kinds of raw materials are accurately weighed, and then the raw materials are thoroughly stirred and mixed until uniform, so as to obtain powder.

[0050] The preparation process of the liquid material is exactly the same as the preparation method of the polyurethane prepolymer in Example 2.

[0051] The mass ratio of powder, water, and polyurethane prepolymer is controlled within the range of 10:0.33:1. The powder and water of the grouting material are thoroughly mixed evenly, and the powder and water are mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer is added to the slurry, and the mixture is further stirred and mixed evenly to obtain the underwater anti-dispersion cement-based grouting repair material.

[0052] Example 9 The underwater anti-dispersion cement-based grouting repair material comprises two parts: liquid and powder. By mass, the powder component includes: According to the established formula, all kinds of raw materials are accurately weighed, and then the raw materials are thoroughly stirred and mixed until uniform, so as to obtain powder.

[0053] The preparation process of the liquid material is exactly the same as the preparation method of the polyurethane prepolymer in Example 2.

[0054] The mass ratio of powder, water, and polyurethane prepolymer is controlled within the range of 10:0.33:1. The powder and water of the grouting material are thoroughly mixed evenly, and the powder and water are mixed according to the predetermined ratio to form a slurry. Then, the polyurethane prepolymer is added to the slurry, and the mixture is further stirred and mixed evenly to obtain the underwater anti-dispersion cement-based grouting repair material.

[0055] Comparative Example 1 The difference between Comparative Example 1 and Example 5 is that no polyurethane prepolymer was added.

[0056] Comparative Example 2 The difference between Comparative Example 2 and Example 5 is that the liquid polyurethane prepolymer did not contain the hydrophilic chain extender sodium 1,4-butanediol-2-sulfonate, but instead used 1,4-butanediol.

[0057] Comparative Example 3 The difference between Comparative Example 3 and Example 5 is that the isocyanate index of the polyurethane prepolymer is 2.

[0058] Comparative Example 4 The difference between Comparative Example 4 and Example 5 is that the isocyanate index of the polyurethane prepolymer is 5.

[0059] Comparative Example 5 The difference between Comparative Example 5 and Example 5 is that the powder does not contain high-belite cement, and all high-belite cement is replaced with silicate cement.

[0060] Comparative Example 6 The difference between Comparative Example 6 and Example 5 is that the powder contains no reinforcing agent.

[0061] Comparative Example 7 The difference between Comparative Example 7 and Example 5 is that the anti-dispersant in the powder is acrylamide.

[0062] Comparative Example 8 The difference between Comparative Example 8 and Example 5 is that all the aggregates in the powder were replaced with 40-80 mesh quartz sand.

[0063] Comparative Example 9 The difference between Comparative Example 9 and Example 5 is that the powder contains no defoamer.

[0064] Comparative Example 10 The difference between Comparative Example 10 and Example 5 is that the powder contains no expanding agent.

[0065] Comparative Example 11 The difference between Comparative Example 11 and Example 5 is that the powder contains no waterproofing agent.

[0066] Comparative Example 12 The difference between Comparative Example 12 and Example 5 is that the proportion of mineral admixtures in the powder (fly ash: silica fume = 1:5).

[0067] Comparative Example 13 The difference between Comparative Example 13 and Example 5 is as follows: The liquid material in this comparative example was prepared by mixing 150 parts of polyoxyethylene glycol (PEG), 80 parts of dicyclohexylmethane diisocyanate (HMDI), 5 parts of sodium 1,4-butanediol-2-sulfonate and 2 parts of organotin catalyst at room temperature until the mixture was homogeneous.

[0068] To comprehensively evaluate the performance of underwater anti-dispersion cement-based grouting repair materials, the following test methods were designed: Setting time, compressive strength and flexural strength: The relevant testing methods in GB / T 17671-2021 "Test Methods for Strength of Cement Mortar" shall be adopted.

[0069] Bleeding rate: The relevant test methods in GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" were adopted.

[0070] Suspended solids content: The relevant testing methods in DL / T 5117-2021 "Test Procedure for Underwater Non-dispersible Concrete" were adopted.

[0071] Impermeability strength, secondary impermeability strength and bonding strength: The relevant testing methods in GB / T23440—2025 "Inorganic Waterproof and Leak-stopping Materials" shall be adopted.

[0072] Flowability and water-to-land strength ratio: The relevant test methods in DL / T 5117-2021 "Test Procedure for Underwater Non-dispersible Concrete" were adopted.

[0073] The material test results of the above embodiments and comparative examples are shown in Tables 1 and 2.

[0074] Table 1 Performance test results of underwater anti-dispersion cement-based grouting repair materials in each embodiment Table 2 Performance test results of underwater anti-dispersion cement-based grouting repair materials for each comparative example As can be seen from Table 1, Table 2, and the attached figures: Compared to Example 5, Comparative Example 1 did not add polyurethane prepolymer. Although the compressive strength of the prepared grouting repair material was improved to a certain extent, the flexural strength was significantly reduced, resulting in a significant decrease in the toughness of the material. Consequently, the material's ability to resist dynamic loads was also weakened.

[0075] Compared to Example 5, the polyurethane prepolymer in Comparative Example 2 did not contain a hydrophilic chain extender, preventing the material from forming a stable and homogeneous phase with the cement paste, thus hindering the material's performance. Compared to traditional hydrophilic chain extenders—2,2-dimethylolbutyric acid (DMBA) and dimethylolpropionic acid (DMPA)—sodium 1,4-butanediol-2-sulfonate exhibits strong electrostatic repulsion, high adsorption stability, and the ability to effectively promote microphase separation, significantly improving the material's mechanical properties while delaying cement hydration. In contrast, carboxylate-type hydrophilic chain extenders primarily work by inhibiting the early hydration rate of cement through complexation, but they do not show significant effectiveness in improving the material's mechanical properties. Figure 1 It can be seen that the grouting repair materials prepared in Example 5 and Comparative Examples 1 and 2 have the following appearance after curing: 2.

[0076] Compared to Example 5, the polyurethane prepolymer in Comparative Example 3 has a lower isocyanate index, resulting in higher flexibility of the polyurethane prepolymer chain segments, which helps to improve the toughness of the material. However, the amount of isocyanate is relatively small. When the prepared grouting material is formed subsequently, these small amounts of isocyanate participate in the formation and construction of the molecular chain, which prevents the mechanical properties of the material from being improved as expected.

[0077] Compared to Example 5, the polyurethane prepolymer in Comparative Example 4 has a higher isocyanate index, increased hard segment content, and restricted chain segment movement, which usually improves the mechanical strength of the material but may lead to increased brittleness and reduced flexibility. However, excessive free isocyanate groups in the polymer result in rapid water reaction, excessive foaming, and an excessively large expansion ratio, which is not conducive to the uniform distribution and dense filling of the grout in the cement matrix, thus affecting the overall performance of the grouting material.

[0078] Compared to Example 5, Comparative Example 5 did not contain high-belite cement in its powder composition. Compared to ordinary Portland cement, high-belite cement exhibits significantly lower heat of hydration. In engineering structures such as concrete, temperature stress induced by heat of hydration is a major factor leading to cracking. High-belite cement, with its low heat of hydration, can effectively reduce this risk of cracking. Furthermore, this cement demonstrates excellent volume stability, as well as superior impermeability, freeze-thaw resistance, and carbonation resistance—properties crucial for ensuring the long-term durability of engineering structures. High-belite cement exhibits good late-stage strength gain, meaning its strength continues to increase during the long-term service life of the engineering structure, thus significantly extending its service life.

[0079] Compared to Example 5, the powder in Comparative Example 6 lacked a reinforcing agent, significantly impacting the material's impermeability. While the material without a reinforcing agent possessed some waterproofing properties, this primarily relied on the closed-cell effect of polyurethane. The reinforcing agent, however, exhibits chemical crystallization, filling the pores formed by the polyurethane at the microscopic level, thereby constructing a double waterproof barrier. Particularly noteworthy is its self-healing ability in the event of secondary leakage, resulting in a longer service life.

[0080] Compared to Example 5, Comparative Example 7 used polyacrylamide, a traditional anti-dispersant agent, in its powder. While achieving good anti-dispersibility, the suspended solids content increased to some extent, indicating that some components of the grouting material were not effectively bound, leading to an increase in suspended solids content. This phenomenon suggests that some components in the grouting material were not effectively bound by polyacrylamide, exhibiting a certain degree of segregation tendency. Furthermore, the introduction of polyacrylamide also caused an increase in viscosity, significantly affecting the material's flowability and causing numerous inconveniences in actual construction operations. The self-developed SBT®-NDA underwater anti-dispersibility concrete admixture demonstrated superior performance. It forms a special protective film on the surface of the grouting material. This protective film acts as a robust barrier, effectively preventing the loss of cement paste and the dispersion of aggregates during underwater pouring, ensuring the integrity and stability of the material. Simultaneously, thanks to advanced molecular design technology, this admixture endows the grouting material with good flowability, ensuring anti-dispersibility performance while also balancing ease and efficiency in construction. Figure 2 This study compares the underwater anti-dispersion effects of Example 5, Comparative Example 7, and ordinary cement-based grouting materials, comparing the effects of having and not having anti-dispersion additives and different types of anti-dispersion additives.

[0081] Compared to Example 5, Comparative Examples 8-11 achieved a significant improvement in material density through systematic aggregate gradation optimization and simultaneous precise optimization of functional additives (including defoamers, expanding agents, and waterproofing agents). Specifically, optimized aggregate gradation helps to construct a denser particle packing structure, reducing the porosity inside the material; while the optimization of functional additives, based on different mechanisms of action, further improves the microstructure and properties of the material. Defoamers effectively eliminate bubbles generated during material preparation, avoiding defects caused by the presence of bubbles; expanding agents produce a moderate expansion effect during material hardening, filling the internal micropores; and waterproofing agents enhance the material's impermeability, preventing internal structural damage caused by water intrusion. These combined effects significantly improve the material's density, thereby achieving a significant enhancement of the material's mechanical properties. Figure 3 To demonstrate the waterproofing effect of the grouting repair materials prepared in Example 5 and Comparative Example 11, after adding the waterproofing agent, the material surface exhibits significant hydrophobic properties, effectively preventing further water leakage.

[0082] Compared to Example 5, Comparative Example 12 uses a non-limited mineral admixture ratio (fly ash: silica fume = 1:5). Fly ash particles are mostly spherical glassy particles, which can act as ball bearings between aggregates, reducing friction between the grout and aggregates, thereby improving the workability and increasing the fluidity of concrete. Silica fume, on the other hand, has a large specific surface area and a high water demand. Adding silica fume will lead to a significant increase in water consumption, resulting in reduced fluidity of the cement-based grouting material. Simultaneously, the setting time is shortened, limiting later-stage strength growth.

[0083] Compared to Example 5, in Comparative Example 13, the components of the liquid were directly incorporated into the cement-based grouting material without undergoing a polymerization reaction. In this case, because no polymerization reaction occurs, the active groups on the polyether molecular chain and the isocyanate groups in the isocyanate are difficult to effectively combine through chemical bonds. Simultaneously, the polyether and isocyanate differ in density, and insufficient stirring during mixing may lead to stratification of the system. Furthermore, the isocyanate groups preferentially react with water in the system to generate insoluble urea compounds. These reaction products are highly likely to induce gelation of the system, or even precipitation, severely affecting the material's performance stability. Finally, it should be noted that the above embodiments provide a simplified description of the preferred embodiment of the present invention. For those skilled in the art, any changes, modifications, substitutions, or alterations to the embodiments of the present invention, inspired by the principles of the present invention, fall within the protection scope of the present invention.

Claims

1. An underwater anti-dispersion cement-based grouting repair material, characterized in that, It includes liquid and powder components, wherein the liquid component is a polyurethane prepolymer, which is prepared by mixing the following raw material components: 100-150 parts of polyol oligomers; 35-80 parts of diisocyanate; 2-5 parts of hydrophilic chain extender; 1-2 parts catalyst; The powder comprises the following components in parts by weight: 80-120 parts cement 10-30 parts of high-Belitte cement 5-10 parts of mineral admixtures Collect 15-20 parts, Anti-dispersant 1-1.5 parts, 1-1.5 parts of expanding agent, Water-reducing agent 0.1~0.5 parts, 0.5-1.5 parts of powder waterproofing agent, Defoamer 0.1~0.5 parts, 0.5-1.5 parts of reinforcing agent; The mass ratio of the powder to the liquid is controlled within the range of 10:1 to 3.

2. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The isocyanate index R in the polyurethane prepolymer is 3~4.

3. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The high belite cement has a strength grade of 62.

5.

4. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The polyol oligomer is selected from any one or a mixture of more than one of polyoxypropylene glycol, polyoxyethylene glycol and polytetrahydrofuran ether glycol; The diisocyanate is selected from any one or a mixture of more than one of diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate; The catalyst is selected from any one or a mixture of one or more amine catalysts and organometallic catalysts. The hydrophilic chain extender is sodium 1,4-butanediol-2-sulfonate.

5. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The antidispersant is SBT. ® -NDA underwater anti-dispersion concrete admixture.

6. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The aggregate is composed of three types of quartz sand with fineness of 40-80 mesh, 80-120 mesh, and 120-200 mesh, and the mass percentage of each component is as follows: 30%-50% 40-80 mesh quartz sand, 30%-50% 80-120 mesh quartz sand, and 10%-30% 120-200 mesh quartz sand; The cement is selected from any one or a mixture of two of the following: grade 52.5 silicate cement and grade 52.5 sulfoaluminate cement. The mineral admixture is spherical fly ash and silica fume, with a mass ratio of 2~3:

1.

7. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The water-reducing agent is selected from any one or a mixture of TC-PC500 powder polycarboxylate water-reducing agent, TC-PC100-T powder polycarboxylate water-reducing agent and TC-PC400 powder polycarboxylate water-reducing agent; The expanding agent is selected from any one or a mixture of calcium sulfoaluminate expanding agents and calcium oxide expanding agents; The powder waterproofing agent is selected from any one or a mixture of more than one of Waterproof Agent Powder 8208, BS POWDER D and BS POWDER B; The defoamer is selected from any one or a mixture of polysiloxane defoamers and organosilicon defoamers; The reinforcing agent is selected from either zirconium silicone or sodium metafeldtate.

8. The underwater anti-dispersion cement-based grouting repair material according to claim 1, characterized in that, The preparation method of the liquid polyurethane prepolymer includes the following steps: (1) Add the measured amount of polyol oligomer to the reactor and heat it to 110~120℃ for vacuum dehydration for 1.5~2h; (2) After the water content is reduced to 0.05%, cool down to 60°C, add diisocyanate and sodium 1,4-butanediol-2-sulfonate and polymerize at 75~85°C for 2~3 hours; (3) After the reaction in step (2) is completed, cool down to 60°C, add catalyst and continue stirring for 30 minutes, then seal and discharge to obtain polyurethane prepolymer.

9. A method for preparing the underwater anti-dispersion cement-based grouting repair material according to any one of claims 1 to 8, characterized in that, The process includes the following: taking each ingredient by weight, mixing them evenly, and packaging.

10. A method of using the underwater anti-dispersion cement-based grouting repair material according to any one of claims 1 to 8, characterized in that, Specifically, the powder of the grouting material is first thoroughly mixed with water, and the powder and water are mixed in a predetermined ratio to form a slurry. Then, liquid polyurethane prepolymer is added to the slurry and further stirred until it is evenly mixed. After that, the grouting operation can be carried out. The mass ratio of the powder, water, and liquid polyurethane prepolymer is controlled within the range of 10:0.33~0.35:1~3.

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