A high-viscosity anti-permeation special caulking paste for bolt holes and a preparation method thereof

Abstract

The application discloses a high-viscosity anti-permeation special caulking paste for bolt holes and a preparation method thereof, and belongs to the technical field of building materials. The caulking paste is prepared by mixing and stirring Portland cement, heavy calcium carbonate, layered-branching composite calcium hydroxysilicate-magnesium calcium aluminate, porous cage-shaped hydrophobically modified calcium zinc aluminosilicate, latex powder, hydroxypropyl methyl cellulose ether, polypropylene fiber, calcium formate, organic silicon water-repellent agent, starch ether and water. The layered-branching composite calcium hydroxysilicate-magnesium calcium aluminate is prepared by parallel flow co-precipitation of a calcium source, an aluminum source, a magnesium source and a silicon source in the presence of a template agent and a buffer solution, and then hydrothermal calcination, so as to form a layer plate-whisker interlocking structure. The porous cage-shaped hydrophobically modified calcium zinc aluminosilicate is prepared by a sol-gel method through step-by-step temperature control complexation, template assembly, calcination and fluorosilane hydrophobic modification, so as to form a porous cage-shaped structure. The application is suitable for plugging of concrete structure bolt holes.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a high-viscosity, impermeable caulking compound for bolt holes and its preparation method. Background Technology

[0002] Bolt holes are a common type of pre-reserved opening during the assembly of precast components and the fixing of formwork. If these holes are not properly sealed, they become weak channels for rainwater seepage and the intrusion of harmful media, seriously affecting the durability of concrete structures. Statistics show that leakage problems caused by improperly sealed bolt holes account for more than 30% of building exterior wall leakage accidents. Therefore, developing specialized caulking materials for bolt holes with high bonding strength, excellent impermeability, and good construction adaptability has significant engineering implications and socio-economic benefits.

[0003] Currently, commonly used caulking materials in engineering mainly include polyurethane, epoxy resin, acrylic resin, and cement-based polymer-modified materials. Polyurethane caulking adhesives have excellent elasticity and adhesion, but they are prone to molecular chain breakage under humid and hot aging environments, leading to a decline in mechanical properties. Furthermore, their alkali resistance is poor, and their long-term compatibility with cementitious substrates is insufficient. Epoxy resin materials have high bonding strength and low curing shrinkage, but they are brittle and lack flexibility after curing, making it difficult to adapt to the micro-deformations of concrete structures, and their adhesion to damp surfaces decreases significantly. Cement-based polymer-modified materials are inexpensive, easy to apply, and have good compatibility with concrete substrates, but traditional formulations suffer from high shrinkage rates and limited impermeability, making it difficult to meet long-term waterproofing requirements under high water pressure environments. In recent years, researchers have attempted to improve the overall performance of caulking materials through methods such as nanomaterial modification, polymer emulsion composite modification, or silane coupling agent surface treatment. However, existing technologies still generally suffer from prominent problems such as poor interfacial compatibility between inorganic fillers and organic matrices, impermeability performance relying on a single hydrophobic component and lacking multi-level structural design, and insufficient bonding strength when applied to damp substrates. Summary of the Invention

[0004] The purpose of this invention is to provide a high-viscosity, impermeable caulking compound for bolt holes and its preparation method, which solves the technical problems of poor interfacial compatibility, insufficient bonding strength on damp substrates, and limited impermeability of existing caulking materials.

[0005] The present invention achieves the above objectives through the following technical solutions: A method for preparing a high-viscosity, impermeable caulking compound for bolt holes, comprising the following steps: S1. By weight, add 25-35 parts of silicate cement, 10-20 parts of heavy calcium carbonate, 15-25 parts of layered-dendritic composite hydroxyl calcium silicate-magnesium calcium aluminate, and 10-20 parts of porous cage-like hydrophobic modified zinc aluminosilicate to a mixer and mix; add 8-15 parts of latex powder, 0.3-0.8 parts of hydroxypropyl methylcellulose ether, 0.1-0.3 parts of polypropylene fiber, 0.5-1.2 parts of calcium formate, 0.5-1.5 parts of organosilicon water-repellent agent, and 0.1-0.3 parts of starch ether, and continue mixing to obtain a dry powder mixture; S2. Add 20-30 parts water to the mixing container, add the dry powder mixture, and stir.

[0006] In this invention, the performance enhancement mechanism of the high-viscosity, impermeable bolt hole caulking compound originates from the multiple synergistic reactions of layered-dendritic composite calcium hydroxysilicate-magnesium aluminate and porous cage-like hydrophobic modified zinc aluminosilicate during cement hydration. When the dry powder mixture is mixed with water, the silicate cement rapidly hydrates to generate hydrated calcium silicate gel and calcium hydroxide, providing initial strength for the caulking compound. The layered structure of the layered-dendritic composite calcium hydroxysilicate-magnesium aluminate is rich in calcium, aluminum, and magnesium active sites, undergoing secondary hydration reactions with cement hydration products to form chemically bonded interfaces. Simultaneously, the positively charged surface of the layers electrostatically adsorbs negatively charged cement particles, further strengthening the interfacial bonding. The dendritic whiskers are distributed in a three-dimensional network within the slurry. When the caulking compound is under stress, the whiskers transfer the load through bridging and absorb fracture energy through pull-out effects during crack propagation, significantly improving the material's bonding toughness. The multi-level pore structure of the porous, hydrophobically modified zinc aluminosilicate calcium silicate exhibits capillary adsorption of cement hydration products. The hydrated calcium silicate gel can penetrate the pores to form mechanically interlocking anchor points. Simultaneously, the fluorine-containing long chains grafted onto its surface form a dense hydrophobic barrier on the capillary walls, effectively blocking the capillary penetration pathway of water molecules. These two modified compounds, along with organic hydrophobic agents and redispersible latex powder, form an "inorganic-organic" synergistic network. The inorganic component provides a rigid framework and chemical bonding, while the organic component provides flexible connections and overall waterproofing. Together, they construct a triple-reinforced system of "chemical bonding-physical anchoring-hydrophobic barrier," enabling the caulking compound to achieve high-strength adhesion even on damp surfaces, while also possessing excellent impermeability and long-term durability.

[0007] According to a preferred embodiment of the present invention, in step S1, the latex powder is a vinyl acetate-ethylene copolymer, and the organosilicon hydrophobic agent is potassium methylsilicate or sodium methylsilicate.

[0008] According to a preferred embodiment of the present invention, the time for step S2 is 3-5 minutes.

[0009] According to a preferred embodiment of the present invention, the preparation method of the layered-dendritic composite calcium hydroxysilicate-magnesium aluminate includes: A1. By weight, dissolve 146.5-158.3 parts of calcium nitrate tetrahydrate and 78.5-85.2 parts of aluminum nitrate nonahydrate in 800-1000 parts of deionized water to obtain solution A; add 12.5-15.8 parts of hexadecyltrimethylammonium bromide to a reactor containing 300-500 parts of deionized water, stir, and add 100-150 parts of ammonia-ammonium chloride buffer solution, stirring to mix; dissolve 128.4-136.9 parts of magnesium nitrate hexahydrate in 300-400 parts of deionized water to obtain solution B1; dissolve 98.7-105... 6 parts of sodium silicate were dissolved in 300-400 parts of deionized water to obtain solution B2; solutions A, B1, and B2 were added to a reaction vessel, and the pH was adjusted to 10.0-10.8 with ammonia water, and stirred to obtain a mixed solution; the mixed solution was transferred to a reaction vessel and subjected to hydrothermal reaction at 180-200℃; after the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged, and the precipitate was obtained; the precipitate was washed successively with deionized water and anhydrous ethanol to obtain a washed precipitate; the washed precipitate was dried in a vacuum drying oven at 80-100℃ to obtain an intermediate; A2. Place the intermediate in a muffle furnace, heat to 550-600℃ and calcine, then cool to room temperature with the furnace, grind and sieve.

[0010] In this invention, the preparation process of the layered-dendritic composite calcium hydroxysilicate-magnesium aluminate follows a synergistic reaction mechanism of "co-precipitation-hydrothermal crystallization-template induction". In an ammonia-ammonium chloride buffer solution, ammonium ions and magnesium ions form a soluble complex ion, effectively inhibiting the rapid precipitation of magnesium ions into magnesium hydroxide under alkaline conditions. Simultaneously, the buffer system stabilizes the reaction environment within a weakly alkaline range, providing suitable conditions for the controllable growth of the layered structure. When a solution containing calcium and aluminum ions is added co-currently with a solution containing magnesium and silicate ions, calcium ions and silicate ions undergo a condensation reaction under alkaline conditions to generate a hydrated calcium silicate gel precursor. Aluminum ions are then embedded in the layered structure of the layered bimetallic hydroxide in a six-coordinate configuration, forming a composite layer of magnesium-aluminum layered bimetallic hydroxide and calcium hydroxysilicate. Hexadecyltrimethylammonium bromide, acting as a cationic template agent, has its hydrophobic chains adsorbed onto the laminate surface during the initial stage of co-precipitation. Through electrostatic interactions and steric hindrance, it inhibits excessive horizontal growth of the laminate, inducing preferential crystal growth along specific crystal planes, thus forming in-situ magnesium calcium aluminate nanocrystals at the laminate edges. Under hydrothermal conditions, as the reaction system temperature increases, the ion diffusion rate accelerates, the laminate structure becomes more regularized, and the whiskers undergo secondary growth to form dendritic morphologies. Finally, high-temperature calcination removes the template agent and promotes crystallization, yielding a laminate-whisker interlocked composite structure. This structure combines the high specific surface area of ​​layered materials with the physical anchoring effect of dendritic materials.

[0011] According to a preferred embodiment of the present invention, in step A1, the hydrothermal reaction time at 180-200°C is 24-36 hours.

[0012] According to a preferred embodiment of the present invention, in step A2, the calcination time at 550-600°C is 4-6 hours.

[0013] According to a preferred embodiment of the present invention, the preparation method of the porous cage-like hydrophobic modified zinc aluminosilicate calcium includes: B1. By weight, dissolve 112.3-120.8 parts tetraethyl silicate, 46.7-52.4 parts aluminum nitrate nonahydrate, 78.9-85.6 parts zinc acetate dihydrate, and 35.2-40.5 parts calcium nitrate tetrahydrate in a mixed solvent of 500-600 parts anhydrous ethanol and 200-250 parts deionized water. At 20-25°C, add 8.0-12.0 parts diethanolamine and stir. Raise the temperature to 35-40°C, then add 15.0-20.0 parts acetylacetone and 5.0-8.0 parts citric acid, and continue stirring. Cool to 25-30°C and adjust the temperature with nitric acid. Adjust the pH of the solution to 1.5-2.5 and pre-hydrolyze at 40-50℃; add 45.6-52.3 parts of polyethylene glycol-1000 and continue stirring; cool to 25-30℃, adjust the pH to 4.0-5.0 with ammonia-ammonium chloride buffer solution, and continue the hydrolysis reaction to obtain a reaction solution; transfer the reaction solution to a rotary evaporator and concentrate under reduced pressure at 58-62℃ to obtain a sol; transfer the sol to a petri dish and dry in a forced-air drying oven at 78-82℃ to obtain a dry gel; place the dry gel in a muffle furnace and calcine at 500-550℃ to obtain porous powder; B2. Disperse the porous powder in 300-400 parts of anhydrous ethanol and ultrasonically disperse it; add 5.0-8.0 parts of anhydrous magnesium sulfate, stir and filter to obtain the filtrate; add 8.5-12.6 parts of heptadecafluorodecyltrimethoxysilane, 1.5-2.5 parts of ammonia and 10-20 parts of molecular sieve 3A to the filtrate, and stir and reflux in a water bath at 58-62℃; after the reaction is completed, centrifuge and wash with anhydrous ethanol and deionized water in sequence, dry in a vacuum drying oven at 58-62℃, grind and sieve.

[0014] In this invention, the preparation of the porous, cage-like, hydrophobically modified zinc aluminosilicate calcium is based on a tandem reaction mechanism of "stepwise temperature-controlled complexation - sol-gel assembly - in-situ hydrophobic grafting". First, diethanolamine is added at low temperature. The amino and hydroxyl groups in its molecule form weak coordination bonds with metal ions, inhibiting premature hydrolysis and aggregation of metal ions through steric hindrance, ensuring uniform dispersion of the sol system. After heating, acetylacetone and citric acid are added. Acetylacetone forms stable six-membered ring complexes with aluminum and zinc ions, while citric acid forms a multidentate chelate structure with calcium ions. Their synergistic effect makes the hydrolysis rate constants of the three metal ions (aluminum, zinc, and calcium) tend to be consistent, laying the foundation for subsequent synchronous condensation with tetraethyl silicate. After adjusting to a strongly acidic environment with nitric acid, tetraethyl silicate hydrolyzes under acid catalysis to generate silanol. At this point, the metal complex remains stable, and the silanol and metal ions form a uniform precursor network through hydrogen bonding. After adding polyethylene glycol as a template agent, its hydrophilic segments assemble with the inorganic precursor through hydrogen bonding to form organic-inorganic hybrid micelles, constituting a mesoporous casting. The pH is slowly increased to a weakly acidic range using an ammonia-ammonium chloride buffer solution, promoting the condensation reaction of silanols with metal ions to form a wet gel with a regular pore structure. After drying, the template agent is removed by calcination, yielding a hierarchical porous cage-like zinc aluminosilicate calcium framework. Finally, under anhydrous conditions, heptadecafluorodecyltrimethoxysilane undergoes a dehydration condensation reaction with the silanol groups on the framework surface under ammonia catalysis, covalently grafting fluorine-containing long chains onto the pore surface through siloxane bonds to form a low surface energy superhydrophobic layer. Simultaneously, anhydrous magnesium sulfate and molecular sieve 3A synergistically remove trace amounts of moisture in the reaction system, inhibiting the self-polymerization side reaction of fluorosilanes and ensuring uniform coverage of the hydrophobic layer.

[0015] According to a preferred embodiment of the present invention, in step B1, the calcination time at 500-550°C is 5-7 hours.

[0016] According to a preferred embodiment of the present invention, in step B2, the stirring and reflux reaction in a water bath at 58-62°C takes 12-16 hours.

[0017] The present invention also provides a high-viscosity, impermeable caulking compound for bolt holes prepared according to the preparation method of the high-viscosity, impermeable caulking compound for bolt holes.

[0018] The beneficial effects of this invention are as follows: The high-viscosity, impermeable caulking compound for bolt holes provided by this invention achieves a significant improvement in interfacial bonding strength and impermeability through the synergistic compounding of two newly designed inorganic modified compounds. The layered-dendritic composite calcium hydroxysilicate-magnesium aluminate, with its unique layered-whisker interlocking structure, provides multiple reinforcement mechanisms: the layered skeleton provides ion exchange sites, forming strong chemical bonds with cement hydration products; the dendritic whiskers, distributed in a three-dimensional network within the hardened slurry, absorb fracture energy through pull-out effect and crack deflection, significantly improving bonding toughness and crack resistance. The porous, cage-like, hydrophobic modified zinc aluminosilicate constructs a hydrophobic barrier pathway; its hierarchical porous structure provides anchoring space for hydration products, forming a mechanical interlock, while the surface fluorosilane hydrophobic layer forms a low surface energy barrier on the capillary walls, effectively preventing water penetration. The two modified compounds work synergistically from the dimensions of "chemical bonding-physical anchoring" and "hydrophobic barrier," enabling the caulking compound to achieve ultra-high bonding strength even on damp substrates.

[0019] In terms of preparation technology, the synthesis processes of the two modified compounds are precisely controlled. The layered-dendritic composite calcium hydroxysilicate-magnesium aluminate is produced using a combination of co-current co-precipitation and hydrothermal crystallization. In an ammonia-ammonium chloride buffer system, magnesium ions are efficiently embedded into the layers, avoiding the formation of magnesium silicate byproducts. Simultaneously, the template agent induces in-situ growth of dendritic whiskers. The porous cage-like hydrophobic modified zinc aluminosilicate utilizes a stepwise temperature-controlled complexation strategy. A three-component complexation system ensures highly matched hydrolysis rates of aluminum, zinc, and calcium metal ions, guaranteeing uniform doping of metal elements within the silicon framework. Combined with template self-assembly and fluorosilane grafting, a porous cage-like structure with both high specific surface area and superhydrophobic properties is obtained. All raw materials are commercially available, demonstrating promising industrialization prospects.

[0020] In practical applications, this sealant exhibits excellent thixotropy and water retention, making it highly adaptable to damp surfaces and allowing for direct application without pre-wetting. After hardening, the gel has low shrinkage, and its bond strength to the concrete substrate is more than twice that of ordinary cement-based sealants. Even in water immersion environments, the bond strength retention rate remains above 90%, and its impermeability meets the requirements for top-grade waterproofing. Two modified compounds participate in the formation of cement hydration products, forming a homogeneous interface with the substrate, avoiding the common interface aging and debonding problems of organic sealants. This sealant can be widely used in precast concrete component assembly joints, external wall bolt holes, and underground pipe penetrations, and is particularly suitable for major infrastructure projects such as subway segments and integrated utility tunnels. Detailed Implementation

[0021] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0022] Example 1 This embodiment provides a method for preparing a high-viscosity, impermeable caulking compound specifically for bolt holes, the steps of which include: S1. 25g silicate cement, 10g heavy calcium carbonate, 15g layered-dendritic composite hydroxyl calcium silicate-magnesium calcium aluminate, and 10g porous cage-like hydrophobic modified zinc aluminosilicate are sequentially added to a mixer and premixed at 200r / min for 10min. Then, 8g vinyl acetate-ethylene copolymer, 0.3g hydroxypropyl methylcellulose ether, 0.1g polypropylene fiber, 0.5g calcium formate, 0.5g potassium methylsilicate, and 0.1g starch ether are added, and the mixture is continued at 200r / min for 15min until the materials are evenly dispersed to obtain a dry powder mixture. S2. Add 20g of deionized water to the mixing container. Under stirring conditions, slowly add the above dry powder mixture at a speed of 200r / min. After the addition is complete, stir at a speed of 400r / min for 3 minutes until there are no dry powder particles. Then stir at a high speed of 800r / min for 2 minutes until the paste is uniform and delicate. This gives you a high-viscosity, impermeable bolt hole caulking compound.

[0023] Preparation of layered-dendritic composite calcium hydroxysilicate-magnesium aluminate: A1. Dissolve 146.5g of calcium nitrate tetrahydrate and 78.5g of aluminum nitrate nonhydrate in 800g of deionized water, stirring at 400r / min until completely dissolved to obtain clear solution A; add 12.5g of hexadecyltrimethylammonium bromide to a reactor containing 300g of deionized water, stirring at 300r / min until dissolved, and add 100g of ammonia-ammonium chloride buffer solution, wherein the ammonium chloride mass concentration is 0.5mol / L and the buffer solution pH is 10.0, and continue stirring for 10min until homogeneous, as the reaction base solution; dissolve 128.4g of magnesium nitrate hexahydrate in 300g of deionized water, stirring at 300r / min until completely dissolved to obtain solution B1; dissolve 98.7g of sodium silicate in 300g of deionized water, stirring at 300r / min until completely dissolved to obtain solution B2; combine solution B1 and solution B2. Mix and stir for 5 min to obtain solution B; add solution A and solution B to the reactor in parallel at a flow rate of 5 mL / min, while using ammonia as a pH adjuster, and monitor and control the pH of the reaction system at a constant 10.0 using an online pH meter, stir at 800 r / min, and control the temperature of the reaction system at 20℃ using an ice-water bath; after the addition is complete, continue stirring for 30 min to obtain a mixed solution; transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor and hydrothermally react at 180℃ for 24 h; after the reaction is completed, allow it to cool naturally to room temperature, and centrifuge at 8000 r / min for 10 min to obtain a precipitate; wash the precipitate three times with 300 mL of deionized water and twice with 300 mL of anhydrous ethanol to obtain a washed precipitate; place the washed precipitate in an 80℃ vacuum drying oven and dry for 12 h to obtain a white powdery intermediate; A2. The above intermediate was placed in a muffle furnace and heated to 550°C at a heating rate of 3°C / min. It was then calcined at this temperature for 4 hours and cooled to room temperature with the furnace. After grinding with a mortar and pestle, it was passed through a 200-mesh sieve to obtain layered-dendritic composite calcium hydroxysilicate-magnesium aluminate.

[0024] Preparation of porous cage-like hydrophobic modified zinc aluminosilicate calcium: B1. Dissolve 112.3g tetraethyl silicate, 46.7g aluminum nitrate nonahydrate, 78.9g zinc acetate dihydrate, and 35.2g calcium nitrate tetrahydrate in a mixed solvent of 500g anhydrous ethanol and 200g deionized water. Stir at 400 rpm for 30 min to obtain a clear solution. Add 8.0g diethanolamine to a 20°C water bath and stir at 400 rpm for 15 min. Raise the water bath temperature to 35°C, then add 15.0g acetylacetone and 5.0g citric acid, and continue stirring at 400 rpm for 30 min. Lower the water bath temperature to 25°C, adjust the pH of the solution to 1.5 with nitric acid, and pre-hydrolyze at 40°C for 1 h. Add 4... 5.6 g of polyethylene glycol-1000 was stirred at 400 r / min for 1 h. The water bath temperature was lowered to 25 °C, and the pH was adjusted to 4.0 with an ammonia-ammonium chloride buffer solution (ammonium chloride concentration: 0.5 mol / L, buffer solution pH: 4.0). The hydrolysis reaction was continued for 4 h to obtain a reaction solution. The reaction solution was transferred to a rotary evaporator and concentrated under reduced pressure at 58 °C and 0.08 MPa to one-third of the original volume to obtain a viscous sol. The sol was transferred to a petri dish and dried in a 78 °C oven for 24 h to obtain a dry gel. The dry gel was placed in a muffle furnace and heated to 500 °C at a heating rate of 2 °C / min, and calcined for 5 h to obtain a white porous powder. B2. The above porous powder was dispersed in 300g of anhydrous ethanol and ultrasonically dispersed at 200W for 30min. 5.0g of anhydrous magnesium sulfate was added, and the mixture was stirred at 300r / min for 30min and then filtered to obtain the filtrate. 8.5g of heptadecafluorodecyltrimethoxysilane, 1.5g of 25% ammonia water and 10g of molecular sieve 3A were added to the filtrate, and the mixture was stirred and refluxed at 300r / min in a 58℃ water bath for 12h. After the reaction was completed, the mixture was centrifuged at 8000r / min for 10min, washed three times with 300mL of anhydrous ethanol and twice with 300mL of deionized water, dried in a vacuum drying oven at 58℃ for 12h, ground in a mortar and pestle, and passed through a 300-mesh sieve to obtain porous cage-like hydrophobic modified zinc aluminosilicate calcium.

[0025] Example 2 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing a high-viscosity, impermeable caulking compound for bolt holes, the steps of which include: S1. Add 30g of silicate cement, 15g of heavy calcium carbonate, 20g of layered-dendritic composite hydroxyl calcium silicate-magnesium calcium aluminate, and 15g of porous cage-like hydrophobic modified zinc aluminosilicate to a mixer and mix. Add 11.5g of vinyl acetate-ethylene copolymer, 0.55g of hydroxypropyl methylcellulose ether, 0.2g of polypropylene fiber, 0.85g of calcium formate, 1.0g of sodium methylsilicate, and 0.2g of starch ether, and continue mixing to obtain a dry powder mixture. S2. Add 25g of water to the mixing container, add the dry powder mixture, and stir for 4 minutes to obtain a high-viscosity, impermeable caulking compound for bolt holes.

[0026] Preparation of layered-dendritic composite calcium hydroxysilicate-magnesium aluminate: A1. Dissolve 152.4g of calcium nitrate tetrahydrate and 81.8g of aluminum nitrate nonahydrate in 900g of deionized water to obtain solution A; add 14.2g of hexadecyltrimethylammonium bromide to a reaction vessel containing 400g of deionized water, stir, and add 125g of ammonia-ammonium chloride buffer solution, stirring to mix; dissolve 132.6g of magnesium nitrate hexahydrate in 350g of deionized water to obtain solution B1; dissolve 102.2g of sodium silicate in 350g of deionized water to obtain solution B2; add solutions A, B1, and B2 to the reaction vessel, adjust the pH to 10.4 with ammonia, stir, and obtain a mixture; transfer the mixture to the reaction vessel and hydrothermally react at 190℃ for 30h; after the reaction, allow it to cool naturally to room temperature, centrifuge to obtain a precipitate; wash the precipitate successively with deionized water and anhydrous ethanol to obtain a washed precipitate; dry the washed precipitate in a vacuum drying oven at 90℃ to obtain an intermediate; A2. The intermediate was placed in a muffle furnace and heated to 575°C for 5 hours. After cooling to room temperature in the furnace, it was ground and sieved to obtain layered-dendritic composite calcium hydroxysilicate-magnesium aluminate.

[0027] Preparation of porous cage-like hydrophobic modified zinc aluminosilicate calcium: B1. Dissolve 116.6g tetraethyl silicate, 49.6g aluminum nitrate nonahydrate, 82.2g zinc acetate dihydrate, and 37.8g calcium nitrate tetrahydrate in a mixed solvent of 550g anhydrous ethanol and 225g deionized water. At 22.5℃, add 10.0g diethanolamine and stir. Raise the temperature to 37.5℃, then add 17.5g acetylacetone and 6.5g citric acid, and continue stirring. Cool to 27.5℃, adjust the pH of the solution to 2.0 with nitric acid, and preheat at 45℃. Hydrolysis was carried out for 1.5 hours; 48.9 g of polyethylene glycol-1000 was added and stirring was continued; the temperature was lowered to 27.5℃, the pH was adjusted to 4.5 with ammonia-ammonium chloride buffer solution, and the hydrolysis reaction was continued for 5 hours to obtain a reaction solution; the reaction solution was transferred to a rotary evaporator and concentrated under reduced pressure at 60℃ to obtain a sol; the sol was transferred to a petri dish and dried in a forced-air drying oven at 80℃ to obtain a dry gel; the dry gel was placed in a muffle furnace and calcined at 525℃ for 6 hours to obtain porous powder; B2. The porous powder was dispersed in 350g of anhydrous ethanol and ultrasonically dispersed. 6.5g of anhydrous magnesium sulfate was added, and the mixture was stirred and filtered to obtain the filtrate. 10.5g of heptadecafluorodecyltrimethoxysilane, 2.0g of ammonia and 15g of molecular sieve 3A were added to the filtrate, and the mixture was stirred and refluxed in a 60℃ water bath for 14h. After the reaction was completed, the mixture was centrifuged, washed successively with anhydrous ethanol and deionized water, dried in a 60℃ vacuum drying oven, ground and sieved to obtain porous cage-like hydrophobic modified zinc aluminosilicate calcium.

[0028] Example 3 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing a high-viscosity, impermeable caulking compound for bolt holes, the steps of which include: S1. Add 35g of silicate cement, 20g of heavy calcium carbonate, 25g of layered-dendritic composite hydroxyl calcium silicate-magnesium calcium aluminate, and 20g of porous cage-like hydrophobic modified zinc aluminosilicate to a mixer and mix. Add 15g of vinyl acetate-ethylene copolymer, 0.8g of hydroxypropyl methylcellulose ether, 0.3g of polypropylene fiber, 1.2g of calcium formate, 1.5g of sodium methylsilicate, and 0.3g of starch ether, and continue mixing to obtain a dry powder mixture. S2. Add 30g of water to the mixing container, add the dry powder mixture, and stir for 5 minutes to obtain a high-viscosity, impermeable caulking compound for bolt holes.

[0029] Preparation of layered-dendritic composite calcium hydroxysilicate-magnesium aluminate: A1. Dissolve 158.3g of calcium nitrate tetrahydrate and 85.2g of aluminum nitrate nonahydrate in 1000g of deionized water to obtain solution A; add 15.8g of hexadecyltrimethylammonium bromide to a reaction vessel containing 500g of deionized water, stir, and add 150g of ammonia-ammonium chloride buffer solution, stirring to mix; dissolve 136.9g of magnesium nitrate hexahydrate in 400g of deionized water to obtain solution B1; dissolve 105.6g of sodium silicate in 400g of deionized water to obtain solution B2; add solutions A, B1, and B2 to the reaction vessel, adjust the pH to 10.8 with ammonia, stir, and obtain a mixed solution; transfer the mixed solution to the reaction vessel and hydrothermally react at 200℃ for 36h; after the reaction is complete, allow it to cool naturally to room temperature, centrifuge to obtain a precipitate; wash the precipitate successively with deionized water and anhydrous ethanol to obtain a washed precipitate; dry the washed precipitate in a vacuum drying oven at 100℃ to obtain an intermediate; A2. The intermediate was placed in a muffle furnace and heated to 600℃ for 6 hours. After cooling to room temperature in the furnace, it was ground and sieved to obtain layered-dendritic composite calcium hydroxysilicate-magnesium aluminate.

[0030] Preparation of porous cage-like hydrophobic modified zinc aluminosilicate calcium: B1. Dissolve 120.8g tetraethyl silicate, 52.4g aluminum nitrate nonahydrate, 85.6g zinc acetate dihydrate, and 40.5g calcium nitrate tetrahydrate in a mixed solvent of 600g anhydrous ethanol and 250g deionized water. At 25°C, add 12.0g diethanolamine and stir. Raise the temperature to 40°C, then add 20.0g acetylacetone and 8.0g citric acid, and continue stirring. Cool to 30°C, adjust the pH of the solution to 2.5 with nitric acid, and prehydrate at 50°C. Hydrolyze for 2 hours; add 52.3 g of polyethylene glycol-1000 and continue stirring; cool to 30°C, adjust the pH to 5.0 with ammonia-ammonium chloride buffer solution, and continue the hydrolysis reaction for 6 hours to obtain a reaction solution; transfer the reaction solution to a rotary evaporator and concentrate under reduced pressure at 62°C to obtain a sol; transfer the sol to a petri dish and dry in a forced-air drying oven at 82°C to obtain a dry gel; place the dry gel in a muffle furnace and calcine at 550°C for 7 hours to obtain porous powder; B2. The porous powder was dispersed in 400g of anhydrous ethanol and ultrasonically dispersed. 8.0g of anhydrous magnesium sulfate was added, and the mixture was stirred and filtered to obtain the filtrate. 12.6g of heptadecafluorodecyltrimethoxysilane, 2.5g of ammonia and 20g of molecular sieve 3A were added to the filtrate, and the mixture was stirred and refluxed in a water bath at 62℃ for 16h. After the reaction was completed, the mixture was centrifuged, washed successively with anhydrous ethanol and deionized water, dried in a vacuum drying oven at 62℃, ground and sieved to obtain porous cage-like hydrophobic modified zinc aluminosilicate calcium.

[0031] Comparative Example 1 The specific implementation method is the same as in Example 1, except that porous cage-like hydrophobic modified zinc aluminosilicate calcium is not added in S1, and the amount of heavy calcium carbonate is increased to 20g, while the rest is the same as in Example 1.

[0032] Comparative Example 2 The specific implementation method is the same as in Example 1, except that layered-dendritic composite calcium hydroxysilicate-magnesium aluminate is not added in S1, and the amount of heavy calcium carbonate is increased to 25g, while the rest is the same as in Example 1.

[0033] Comparative Example 3 The specific implementation method is the same as in Example 1, except that layered-dendritic composite calcium hydroxysilicate-magnesium aluminate and porous cage-like hydrophobic modified zinc aluminosilicate are not added in S1, and the amount of heavy calcium carbonate is increased to 45g.

[0034] Performance testing The high-viscosity, impermeable caulking compound for bolt holes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following method, which included the following steps: Standard curing bond strength test: The sealant to be tested was applied to the surface of a concrete substrate with dimensions of 100mm × 100mm × 20mm. The coated area was 50mm × 50mm, and the coating thickness was 3mm. After application, the substrate was cured under standard curing conditions of 23±2℃ and 50±5% relative humidity for 28 days. Tensile bond strength was tested using an electronic universal testing machine at a loading rate of 5mm / min, with the loading direction perpendicular to the substrate surface. The maximum load at which the specimen failed was recorded. The bond strength was calculated using the formula σ = F / S, where σ is the bond strength in MPa, F is the maximum load in N, and S is the coated area in mm². 2 For each group of tests, the arithmetic mean of 5 specimens is taken as the final test result.

[0035] Wet substrate bond strength test: The concrete substrate was pre-immersed in deionized water for 24 hours, then removed and wiped dry with a damp cloth. The substrate was then coated with caulking compound according to the standard curing bond strength test method described above and cured for 28 days. Tensile bond strength was tested using an electronic universal testing machine at a loading rate of 5 mm / min. Five specimens were tested in each group, and the arithmetic mean was taken as the final test result. The wet substrate bond strength retention rate was calculated using the formula η = σwet / σstandard × 100%, where η is the retention rate in %, σwet is the wet substrate bond strength in MPa, and σstandard is the standard curing bond strength in MPa.

[0036] Permeability pressure test: The sealant to be tested is molded into a cylindrical specimen with a diameter of 70 mm and a thickness of 20 mm. It is placed under standard curing conditions of 23±2℃ and 50±5% relative humidity for 28 days. The specimen is then placed in the mold of the permeability tester and sealed with sealing material. The initial pressure is 0.1 MPa. After maintaining the pressure for 8 hours, the upper surface of the specimen is observed for any water seepage. If there is no water seepage, the pressure is increased by 0.1 MPa and maintained for another 8 hours. The pressure is gradually increased until three seepage points appear on the upper surface of the specimen. The pressure value at this time is recorded as the permeability pressure in MPa. The arithmetic mean of the three specimens tested in each group is taken as the final test result.

[0037] Shrinkage test: The sealant to be tested was molded into a long strip specimen of 20mm×20mm×160mm and cured under standard curing conditions of 23±2℃ and 50±5% relative humidity for 28 days. The initial length and the length after curing were measured using a length comparator. The shrinkage rate was calculated according to the formula ε=(L0-L) / L0×100%, where ε is the shrinkage rate in %, L0 is the initial length in mm, and L is the length after curing in mm. The arithmetic mean of 3 specimens in each group was taken as the final test result.

[0038] Consistency test: The mortar consistency tester is used. After the mortar to be tested is stirred evenly, it is poured into a conical mold. After filling, the upper surface is smoothed. The conical mold is lifted vertically, allowing the mortar to sink freely under gravity. After 30 seconds, the depth of the cone is measured. This depth value is the consistency value in mm. Each group of tests is performed 3 times, and the arithmetic mean is taken as the final test result.

[0039] Workable time test: Under standard curing conditions of 23±2℃ and 50±5% relative humidity, the sealant to be tested is stirred evenly and allowed to stand. The consistency is tested every 15 minutes according to the consistency test method described above. When the consistency drops to 70% of the initial consistency value, the time elapsed from the end of stirring to this point is recorded. This time is the workable time in minutes. Each group of tests is repeated 3 times and the arithmetic mean is taken as the final test result.

[0040] Test results: Table 1: Test results of each embodiment and comparative example ; As can be seen from Table 1, Examples 1-3 are significantly better than Comparative Examples 1-3 in key performance indicators such as standard curing bond strength, wet substrate bond strength, wet substrate bond strength retention rate, impermeability pressure, and shrinkage rate. This fully demonstrates that the present invention effectively solves the technical problems existing in the existing caulking materials through the synergistic effect of layered-dendritic composite calcium hydroxysilicate-magnesium aluminate and porous cage-like hydrophobic modified zinc aluminosilicate.

[0041] Specifically, regarding interfacial compatibility, the standard curing bond strengths of Examples 1-3 reached 2.86 MPa, 3.12 MPa, and 3.35 MPa, respectively, while those of Comparative Example 1 were only 2.41 MPa, Comparative Example 2 only 2.35 MPa, and Comparative Example 3 only 1.68 MPa. This indicates that the two modified compounds can form stronger chemical bonds and physical anchoring with the cement matrix, significantly improving interfacial bonding. At the same time, the shrinkage rates of Examples 1-3 were only 0.042%, 0.038%, and 0.035%, respectively, which were far lower than those of Comparative Example 1 (0.058%), Comparative Example 2 (0.062%), and Comparative Example 3 (0.085%), further demonstrating that the modified compounds effectively inhibited volume shrinkage and improved interfacial compatibility. Regarding the adhesion strength to a damp substrate, the adhesion strengths of Examples 1-3 reached 2.51 MPa, 2.78 MPa, and 3.01 MPa, respectively, with retention rates as high as 87.8%, 89.1%, and 89.9%. In contrast, the adhesion strength of Comparative Example 1 was only 1.96 MPa with a retention rate of 81.3%, the adhesion strength of Comparative Example 2 was only 2.02 MPa with a retention rate of 86.0%, and the adhesion strength of Comparative Example 3 was only 1.25 MPa with a retention rate of 74.4%. This indicates that the fluorine-containing long chains grafted onto the porous, hydrophobic modified zinc aluminosilicate calcium surface form an effective hydrophobic barrier, preventing moisture from accumulating at the interface and ensuring that the sealant can maintain high-strength adhesion to a damp substrate. In terms of impermeability, the impermeability pressures of Examples 1-3 reached 1.52 MPa, 1.68 MPa and 1.82 MPa respectively, while those of Comparative Example 1 were only 1.23 MPa, Comparative Example 2 was only 1.08 MPa and Comparative Example 3 was only 0.76 MPa. This indicates that the two modified compounds constructed a multi-level impermeability system through the tortuous diffusion path of the layered structure and the hydrophobic barrier effect of the cage structure, respectively, which fundamentally solved the problem of the single impermeability performance and easy leakage of traditional caulking materials.

[0042] Comparative Example 1 lacked porous cage-like hydrophobic modified zinc aluminosilicate calcium, resulting in a missing hydrophobic barrier and thus lower bonding strength and impermeability pressure on damp substrates compared to the Example. Comparative Example 2 lacked layered-dendritic composite hydroxyl calcium silicate-magnesium aluminate calcium, weakening chemical bonding and physical anchoring effects, leading to significant deterioration in standard curing bonding strength, shrinkage rate, and impermeability pressure. Comparative Example 3 lacked both modified compounds, resulting in the worst performance across all categories, further confirming the indispensability of their synergistic effect.

[0043] In summary, this invention successfully overcomes the technical challenges of poor interfacial compatibility, insufficient bonding strength on damp substrates, and limited impermeability by synergistic enhancement of two novel inorganic modified compounds.

[0044] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-viscosity, impermeable caulking compound for bolt holes, characterized in that the steps include... include: S1. By weight, add 25-35 parts of silicate cement, 10-20 parts of heavy calcium carbonate, 15-25 parts of layered-dendritic composite hydroxyl calcium silicate-magnesium calcium aluminate, and 10-20 parts of porous cage-like hydrophobic modified zinc aluminosilicate to a mixer and mix; add 8-15 parts of latex powder, 0.3-0.8 parts of hydroxypropyl methylcellulose ether, 0.1-0.3 parts of polypropylene fiber, 0.5-1.2 parts of calcium formate, 0.5-1.5 parts of organosilicon water-repellent agent, and 0.1-0.3 parts of starch ether, and continue mixing to obtain a dry powder mixture; S2. Add 20-30 parts water to the mixing container, add the dry powder mixture, and stir.

2. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 1, characterized in that, In step S1, the latex powder is a vinyl acetate-ethylene copolymer, and the organosilicon hydrophobic agent is potassium methylsilicate or sodium methylsilicate.

3. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 1, characterized in that, In step S2, the time is 3-5 minutes.

4. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 1, characterized in that, The preparation method of the layered-dendritic composite calcium hydroxysilicate-magnesium aluminate includes: A1. By weight, dissolve 146.5-158.3 parts of calcium nitrate tetrahydrate and 78.5-85.2 parts of aluminum nitrate nonahydrate in 800-1000 parts of deionized water to obtain solution A; add 12.5-15.8 parts of hexadecyltrimethylammonium bromide to a reactor containing 300-500 parts of deionized water, stir, and add 100-150 parts of ammonia-ammonium chloride buffer solution, stirring to mix; dissolve 128.4-136.9 parts of magnesium nitrate hexahydrate in 300-400 parts of deionized water to obtain solution B1; dissolve 98.7-105... 6 parts of sodium silicate were dissolved in 300-400 parts of deionized water to obtain solution B2; solutions A, B1, and B2 were added to a reaction vessel, and the pH was adjusted to 10.0-10.8 with ammonia water, and stirred to obtain a mixed solution; the mixed solution was transferred to a reaction vessel and subjected to hydrothermal reaction at 180-200℃; after the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged, and the precipitate was obtained; the precipitate was washed successively with deionized water and anhydrous ethanol to obtain a washed precipitate; the washed precipitate was dried in a vacuum drying oven at 80-100℃ to obtain an intermediate; A2. Place the intermediate in a muffle furnace, heat to 550-600℃ and calcine, then cool to room temperature with the furnace, grind and sieve.

5. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 4, characterized in that, In step A1, the hydrothermal reaction time at 180-200℃ is 24-36 hours.

6. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 4, characterized in that, In step A2, the calcination time at 550-600℃ is 4-6 hours.

7. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 1, characterized in that, The preparation method of the porous cage-like hydrophobic modified zinc aluminosilicate calcium includes: B1. By weight, dissolve 112.3-120.8 parts tetraethyl silicate, 46.7-52.4 parts aluminum nitrate nonahydrate, 78.9-85.6 parts zinc acetate dihydrate, and 35.2-40.5 parts calcium nitrate tetrahydrate in a mixed solvent of 500-600 parts anhydrous ethanol and 200-250 parts deionized water. At 20-25°C, add 8.0-12.0 parts diethanolamine and stir. Raise the temperature to 35-40°C, then add 15.0-20.0 parts acetylacetone and 5.0-8.0 parts citric acid, and continue stirring. Cool to 25-30°C and adjust the temperature with nitric acid. Adjust the pH of the solution to 1.5-2.5 and pre-hydrolyze at 40-50℃; add 45.6-52.3 parts of polyethylene glycol-1000 and continue stirring; cool to 25-30℃, adjust the pH to 4.0-5.0 with ammonia-ammonium chloride buffer solution, and continue the hydrolysis reaction to obtain a reaction solution; transfer the reaction solution to a rotary evaporator and concentrate under reduced pressure at 58-62℃ to obtain a sol; transfer the sol to a petri dish and dry in a forced-air drying oven at 78-82℃ to obtain a dry gel; place the dry gel in a muffle furnace and calcine at 500-550℃ to obtain porous powder; B2. Disperse the porous powder in 300-400 parts of anhydrous ethanol and ultrasonically disperse it; add 5.0-8.0 parts of anhydrous magnesium sulfate, stir and filter to obtain the filtrate; add 8.5-12.6 parts of heptadecafluorodecyltrimethoxysilane, 1.5-2.5 parts of ammonia and 10-20 parts of molecular sieve 3A to the filtrate, and stir and reflux in a water bath at 58-62℃; after the reaction is completed, centrifuge and wash with anhydrous ethanol and deionized water in sequence, dry in a vacuum drying oven at 58-62℃, grind and sieve.

8. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 7, characterized in that, In step B1, the calcination time at 500-550℃ is 5-7 hours.

9. The preparation method of the high-viscosity, impermeable caulking compound for bolt holes according to claim 7, characterized in that, In step B2, the stirring and reflux reaction in a water bath at 58-62℃ takes 12-16 hours.

10. A high-viscosity, impermeable caulking compound for bolt holes, characterized in that, The high-viscosity, impermeable caulking compound for bolt holes is prepared by the method described in any one of claims 1-9.