Impervious corrosion-resistant grouting material suitable for chlorine salt environment and preparation method thereof

Abstract

The application relates to a kind of anti-permeation and anti-corrosion grouting materials suitable for chlorine salt environment and a preparation method thereof, and belongs to the field of grouting materials.The grouting material comprises A liquid and B liquid, and the weight ratio of A liquid to B liquid is (8-10):1.A liquid comprises the following components in the following weight proportions: 840 parts of silicate cement clinker, 70-90 parts of sulphoaluminate cement clinker, 70-90 parts of gypsum, 200-300 parts of fly ash, 50-100 parts of silica fume, 10-15 parts of water reducing agent and 3-8 parts of early strength agent.B liquid comprises the following components in the following weight proportions: 15 parts of iron-based layered double hydroxide, 3-3.5 parts of nano-silica sol, 6-7.5 parts of nano-montmorillonite and 0.4-0.6 parts of dispersing agent.The application significantly improves the compactness, anti-permeability and long-term anti-corrosion performance of the grouting material, and is suitable for rapid repair and long-term reinforcement of various chlorine salt environment engineering.

Description

Technical Field

[0001] This invention belongs to the field of grouting materials technology, and particularly relates to an anti-permeability and anti-corrosion grouting material suitable for chloride salt environments and its preparation method. Background Technology

[0002] With the continuous expansion of industrial engineering construction, the service life of various engineering facilities in chloride-salt environments is becoming increasingly prominent. Chloride-salt environments are widely present in marine engineering, coastal buildings, inland salt lakes, saline soil areas, and chemical chloride-salt areas. High concentrations of chloride ions in these environments can corrode cement-based materials, directly affecting the safety, stability, and durability of engineering structures. Grouting materials for chloride-salt environments are used as core materials for engineering reinforcement and repair, and their improved impermeability and corrosion resistance have become crucial for ensuring the long-term service life of engineering projects in chloride-salt environments.

[0003] In a chloride-rich environment, chloride ions act as the core corrosive medium, penetrating into the concrete through pores and cracks. This disrupts the highly alkaline environment of the concrete pore solution, causing the passivation film on the steel reinforcement to become unstable and break down. Furthermore, under the combined action of oxygen and moisture, chloride ions catalyze an electrochemical corrosion reaction in the steel reinforcement, generating rust products that expand in volume. This corrosion process further triggers a series of structural defects, including concrete surface peeling, the extension and expansion of longitudinal surface cracks, gradual thinning of the steel reinforcement cross-section, and a significant weakening of the bond between the steel reinforcement and concrete. Ultimately, this leads to a substantial decrease in the load-bearing capacity of the concrete structure, irreversible structural damage, severely shortening the service life of concrete structures in chloride-rich environments, and threatening the operational safety of the project.

[0004] Effectively controlling the adsorption and penetration of chloride ions in cement-based materials under chloride-salt environments, and improving their corrosion resistance and impermeability, is a core requirement for extending the service life of concrete structures under chloride-salt environments and ensuring the safety and stability of engineering projects. Although various grouting materials have been disclosed in existing technologies, they still have significant shortcomings.

[0005] Existing patents (such as CN202211002129.7 and CN202010802828.4) only improve the material density by adding mineral admixtures, bentonite, or graphene oxide, and rely on physical barriers to achieve impermeability. They lack an active capture and locking mechanism for chloride ions, and their performance is still prone to decline in the later stages of chloride salt corrosion, resulting in poor long-term corrosion resistance.

[0006] High early strength grouting materials (such as CN202511712796.8) can meet the needs of rapid repair, but the high heat of hydration of the cementing system makes it easy to generate shrinkage cracks, which in turn provides a channel for chloride ion penetration. Furthermore, the composition has not been optimized for chloride salt environments, resulting in insufficient corrosion protection.

[0007] Other existing patents use non-cement-based systems such as polyurethane and geopolymers (e.g., CN202511712796.8, CN202511428523.0). Although they have improved in terms of fluidity or early strength, they have problems such as poor compatibility with cement matrix and unclear resistance to chloride ion erosion mechanism, making them difficult to adapt to the scenario of repairing concrete structures in chloride salt environment.

[0008] In summary, existing grouting materials for chloride-salt environments generally suffer from problems such as relying solely on physical barriers, lacking active chloride capture mechanisms, difficulty in achieving both early strength and long-term corrosion protection, and poor compatibility of some systems with cementitious matrices. Therefore, developing a grouting material for chloride-salt environments that combines high early strength, excellent workability, a dual corrosion resistance mechanism of physical barriers and active chloride capture, and has a simple preparation process and stable and controllable performance has become an urgent technical problem to be solved in the field of engineering materials. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, this invention provides an impermeable and corrosion-resistant grouting material for chloride-salt environments and its preparation method. The grouting material of this invention has excellent impermeability and chloride ion capture and adsorption capabilities through a dual protection mechanism combining macroscopic physical barrier and microscopic active adsorption. When applied to grouting reinforcement in chloride-salt environment engineering projects, it can achieve rapid repair and reinforcement effects. At the same time, through good impermeability and a long-term chloride ion adsorption mechanism, it meets the safety and long-term service life requirements of engineering construction in chloride-salt environments.

[0010] The technical solution adopted by this invention to solve its technical problem is: A grouting material suitable for chloride salt environments that is impermeable and corrosion resistant, the grouting material comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is (8-10):1; The A liquid comprises the following components in parts by weight: 840 parts of silicate cement clinker, 70-90 parts of sulfoaluminate cement clinker, 70-90 parts of gypsum, 200-300 parts of fly ash, 50-100 parts of silica fume, 10-15 parts of water-reducing agent, and 3-8 parts of early-strength agent. The B solution comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide (iron-based LDHs), 3-3.5 parts of nano-silica sol, 6-6.75 parts of nano-montmorillonite, and 0.4-0.6 parts of dispersant.

[0011] Furthermore, the gypsum is a mixture of dihydrate gypsum and anhydrite, with a weight ratio of 3:6.5-7.

[0012] The early strength agent is a compound of triethanolamine and calcium nitrate, wherein the weight ratio of triethanolamine to calcium nitrate is 1:30-55.

[0013] The water-reducing agent is a polycarboxylate water-reducing agent, and the water-cement ratio of the A solution is 0.30-0.35.

[0014] The iron-based LDHs are made by mixing LDHs-CF and LDHs-CFA in a mass ratio of 6:4-5.

[0015] The average particle size of the nano-silica sol is 10-30 nm; the average particle size of the nano-montmorillonite is 80-100 nm.

[0016] A method for preparing a permeability-resistant and corrosion-resistant grouting material suitable for chloride salt environments, the method comprising the following steps: Step 1: Put silicate cement clinker, sulfoaluminate cement clinker and anhydrite into a ball mill or vertical mill for co-grinding in a certain proportion; Step 2: Add the obtained composite cement base material, fly ash, and silica fume into a forced dry powder mixer and dry mix them evenly at high speed. Step 3: Pour the measured mixing water into the mixing tank according to the water-to-binder ratio of 0.30-0.35, and add polycarboxylate superplasticizer, calcium nitrate and triethanolamine in sequence to prepare a solution; Step 4: While stirring at low speed, slowly add the dry powder to the solution and stir at low speed until the dry powder is completely wetted. After the addition is completed, switch to high speed stirring and shearing to obtain solution A. Step 5: Mix LDHs-CF and LDHs-CFA at a mass ratio of 6:4.5-5 to obtain an iron-based bimetallic hydroxide. Step 6: Add nano silica sol, nano montmorillonite and iron-based bimetallic hydroxide to deionized water at a solid-liquid ratio of 1:20-1:30 and mix with a dispersant. Step 7: Use an ultrasonic disperser to perform ultrasonic treatment to fully disperse the nanoparticles in water, obtaining solution B; Step 8: Add liquid A to liquid B according to the set ratio, stir evenly, and then form the grouting material.

[0017] Further, in step 5, the preparation process of LDHs-CF is as follows: calcium nitrate tetrahydrate and ferric nitrate nonahydrate are dissolved in deionized water according to a set molar ratio to prepare solution 1, and NaOH and alcohol are mixed to prepare mixed solution 2; under magnetic stirring, solution 1 is added dropwise to solution 2 according to a set volume ratio, and magnetic stirring is continued. After the reaction is completed, the mixture is centrifuged multiple times, washed with deionized water until neutral, and then dried in a vacuum drying oven and ground into powder to obtain LDHs-CF.

[0018] Furthermore, in step 5, calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate are dissolved in deionized water according to a set molar ratio to prepare solution 3, and NaOH and NaNO3 are dissolved in deionized water to prepare solution 4. Solutions 3 and 4 are simultaneously added dropwise to a three-necked flask containing alcohol and NaOH according to a set volume ratio, and magnetic stirring is performed. The mixture is then transferred to an autoclave and crystallized at a set temperature. After the reaction, the mixture is centrifuged multiple times and washed until neutral. It is then dried in a vacuum drying oven and ground into powder to obtain LDHs-CFA.

[0019] In this invention, the dihydrate gypsum is used because it dissolves quickly and can rapidly provide... It inhibits early rapid setting, ensuring normal construction time; anhydrite has a large dissolution rate in the later stages, continuously providing... This ensures the stability of ettringite in the later stages, increases the density of the system, and thus improves compressive strength and resistance to chloride salt corrosion.

[0020] The cement used is a silicate-sulfoaluminate composite cement, which serves as the main cementing material. The acicular ettringite generated from sulfoaluminate forms a spatial framework, while the CSH gel generated from silicate cement fills the space. The two work synergistically to provide good mechanical strength for engineering applications in chloride-salt environments.

[0021] The glassy phase in the fly ash particles undergoes a secondary reaction with the calcium hydroxide produced during cement hydration. The addition of fly ash replaces part of the cement, reducing the heat of hydration. At the same time, the micro-expansion effect of CSA in the composite system can compensate for the possible shrinkage of the fly ash-silicate system, reduce cracks, and prevent chloride ions from penetrating into the material through cracks.

[0022] The silica fume reacts extremely quickly with the calcium hydroxide produced during the hydration of silicate cement to generate high-density CSH gel. This gel fills the tiny pores between silicate-sulfoaluminate cement particles and fly ash particles, improving the density of the structure and physically reducing the channels for chloride ion penetration.

[0023] The water-reducing agent is a polycarboxylate water-reducing agent, which can significantly reduce the water-cement ratio and improve strength; in this invention, the water-cement ratio prepared by liquid A is 0.30-0.35.

[0024] The early-strength agent is a compound of triethanolamine and calcium nitrate, which can synergistically promote early cement hydration, provide early strength, and meet the construction needs of rapid repair of projects in chloride-salt environments.

[0025] The iron-based LDHs can exchange nitrate ions between the interlayer layers with externally invading chloride ions, thereby locking harmful chloride ions between the material layers and achieving active capture and adsorption of chloride ions.

[0026] Iron-based LDHs are made by mixing LDHs-CF and LDHs-CFA in a mass ratio of 6:4.5-5. Under this ratio, the binding capacity and structural stability of iron-based LDHs for chloride ions are optimal in a chloride salt environment.

[0027] The LDHs-CF includes the following preparation process: Preparation of solution 1: Dissolve calcium nitrate tetrahydrate and ferric nitrate nonahydrate in 50 mL of deionized water at a molar ratio of 2:1; Solution 2: 100ml is prepared by mixing NaOH and alcohol; Under magnetic stirring at 300-500 rpm, add solution 1 dropwise to solution 2 and continue magnetic stirring for 20-24 hours. After the reaction is complete, centrifuge the mixture multiple times and wash it with deionized water until neutral. Then place it in a vacuum drying oven and dry it at 75℃-80℃ for 10-12 hours; The dried solid was ground into powder using a ball mill to obtain LDHs-CF.

[0028] The LDHs-CFA includes the following preparation process: Preparation of solution 3: Dissolve calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate in 100 mL of deionized water in a molar ratio of 10:1:4; Preparation of solution 4: Dissolve NaOH and NaNO3 in 100 mL of deionized water; Add solutions 3 and 4 dropwise simultaneously into a three-necked flask containing 100 ml of a mixed solution of ethanol and NaOH, with the ratio of ethanol to NaOH being 1:4. Stir magnetically at 300-500 rpm for 2-3 hours. The resulting mixture was transferred to an autoclave and crystallized at 100℃-110℃ for 17-19 hours. After the reaction, centrifuge multiple times and wash until neutral. Dry in a vacuum drying oven at 75℃-80℃ for 10-12 hours, then grind into powder to obtain LDHs-CFA.

[0029] The iron-based LDHs have low metal ion solubility and are more stable in the highly alkaline environment of cement-based materials, and can play a long-term chloride ion capture role in chloride salt environments.

[0030] The iron-based LDHs have a stronger binding capacity for chloride ions; in addition, since Ca, Fe, and Al are common elements in cement, this material has better compatibility with the cement matrix and will not have a negative impact on the performance of concrete, making it suitable for use in cement-based grouting materials in chloride salt environments.

[0031] The nano-silica sol and nano-montmorillonite employ a two-dimensional micro / nano sheet structure, which can increase the tortuosity of the internal capillaries of cement-based materials, thereby physically blocking the transport of water and salt, and further improving the material's resistance to chloride salt penetration.

[0032] The preparation method of this invention, through the combination of liquid A and liquid B, achieves protection from the macroscopic to the microscopic level. It is specifically designed for the chloride ion problem in chloride salt environments and has a significant protective effect.

[0033] In this process, solution A constructs a macroscopic mechanical framework through a hydration reaction, while the nanoparticles and LDH sheets in solution B fill the pores generated by solution A at a multi-level scale, greatly increasing the tortuosity of the chloride ion permeation path, creating extremely high density, and reducing the amount of chloride ion permeation.

[0034] Among them, the highly dense structure of liquid A enables passive barrier against corrosive media, reducing the total amount of chloride ions penetrating from the source.

[0035] Among them, the iron-based LDHs in solution B achieve active capture and locking of infiltrated chloride ions through ion exchange and adsorption mechanisms. Even if a small amount of chloride ions infiltrate, they can be effectively fixed to prevent them from corroding the steel bars and cement matrix.

[0036] This invention combines passive defense and active adsorption in the grouting material, significantly improving its long-term corrosion resistance in chloride-rich environments. Liquid A ensures the grouting material possesses excellent workability, controllable setting time, and high early strength, meeting the construction requirements for rapid repair in chloride-rich environments. Liquid B, without affecting the matrix properties and mechanical properties, endows the material with excellent impermeability and chloride corrosion resistance, enabling the grouting material to meet the dual needs of rapid repair and long-term reinforcement in chloride-rich projects.

[0037] The beneficial effects of this invention are mainly reflected in: 1. Excellent mechanical properties: the grouting material has a 7-day compressive strength ≥60MPa and a 28-day compressive strength ≥70MPa, exhibiting high early strength and enabling rapid repair of projects in chloride-salt environments; 2. It has a strong chloride ion capture capacity, with the free chloride ion content in the material ≤0.33%, which is more than 30% higher than the chloride ion adsorption capacity of existing grouting materials for chloride-salt environments; 3. It has good long-lasting resistance to chloride salt corrosion. The dual protection mechanism of macroscopic barrier and active adsorption extends the service life of the material by more than 50% in high chloride salt environment. 4. It has good compatibility with cement matrix. The constituent elements of iron-based LDHs are common elements in cement and will not have a negative impact on the matrix performance. In addition, it has excellent construction fluidity and meets the requirements of various on-site grouting construction in chloride salt environment. 5. The preparation method is simple and controllable, and the process parameters are clearly quantified. It is suitable for industrial production and on-site preparation and can be widely used in engineering reinforcement and remediation of various chloride-contaminated environments such as marine, coastal, saline soil, and chemical chloride-contaminated areas. Attached Figure Description

[0038] Figure 1 This is a flowchart of the LDHs-CF preparation process.

[0039] Figure 2 This is a flowchart of the LDHs-CFA preparation process.

[0040] Figure 3 This is a diagram illustrating the physical reinforcement mechanism of an anti-permeability and anti-corrosion grouting material suitable for chloride-salt environments.

[0041] Figure 4 This is a diagram illustrating the mechanism by which iron-based LDHs capture chloride ions in grouting materials suitable for chloride-salt environments that resist permeation and corrosion. Detailed Implementation

[0042] The present invention will now be further described with reference to the accompanying drawings.

[0043] Reference Figures 1-4 A grouting material suitable for chloride salt environments that is impermeable and corrosion resistant, the grouting material comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is (8-10):1; The A liquid comprises the following components in parts by weight: 840 parts of silicate cement clinker, 70-90 parts of sulfoaluminate cement clinker, 70-90 parts of gypsum, 200-300 parts of fly ash, 50-100 parts of silica fume, 10-15 parts of water-reducing agent, and 3-8 parts of early-strength agent. The B solution comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide (iron-based LDHs), 3-3.5 parts of nano-silica sol, 6-6.75 parts of nano-montmorillonite, and 0.4-0.6 parts of dispersant.

[0044] Furthermore, the gypsum is a mixture of dihydrate gypsum and anhydrite, with a weight ratio of 3:6.5-7. The early-strength agent is a compound of triethanolamine and calcium nitrate, wherein the weight ratio of triethanolamine to calcium nitrate is 1:30-55. The water-reducing agent is a polycarboxylate water-reducing agent, and the water-cement ratio prepared by solution A is 0.30-0.35.

[0045] The iron-based LDHs are made by mixing LDHs-CF and LDHs-CFA at a mass ratio of 6:4.5-5. The average particle size of the nano-silica sol is 10-30 nm; the average particle size of the nano-montmorillonite is 80-100 nm.

[0046] A method for preparing a permeability-resistant and corrosion-resistant grouting material suitable for chloride salt environments, the method comprising the following steps: Step 1: Put silicate cement clinker, sulfoaluminate cement clinker and anhydrite into a ball mill or vertical mill for co-grinding in a certain proportion; Step 2: Put the obtained composite cement substrate, fly ash, and silica fume into a forced dry powder mixer and dry mix at high speed for 5-8 minutes. Step 3: Pour the measured mixing water into the mixing tank according to the water-to-binder ratio of 0.30-0.35, and add polycarboxylate superplasticizer, calcium nitrate and triethanolamine in sequence to prepare a solution; Step 4: While stirring at a low speed of 200-300 rpm, slowly add the dry powder to the solution and stir at low speed for 5-10 minutes until the dry powder is completely wetted. After the addition is completed, switch to high speed stirring and shearing at 800-1200 rpm for 3-5 minutes to obtain solution A. Step 5: Mix LDHs-CF and LDHs-CFA at a mass ratio of 6:4.5-5 to obtain iron-based morphological bimetallic hydroxides, i.e., iron-based LDHs; Step 6: Add 3-3.5 parts of nano silica sol, 6-6.75 parts of nano montmorillonite, and 15 parts of iron-based bimetallic hydroxide to deionized water at a solid-liquid ratio of 1:20-1:30 and mix. At the same time, add 0.4-0.6 parts of dispersant and mix evenly. Step 7: Use a 300-500W ultrasonic disperser to perform ultrasonic treatment for 60-90 seconds to fully disperse the nanoparticles in water and obtain solution B; Step 8: Add liquid A to liquid B at a weight ratio of 8-10, stir evenly, and then form into grouting material.

[0047] Example 1 A grouting material with anti-permeability and anti-corrosion properties suitable for engineering in chloride salt environments, comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is 8; Liquid A comprises the following components in parts by weight: 840 parts silicate cement clinker, 80 parts sulfoaluminate cement clinker, 80 parts gypsum (including 24 parts dihydrate gypsum and 56 parts anhydrite), 250 parts fly ash, 75 parts silica fume, 12.5 parts polycarboxylate superplasticizer, and 5.5 parts early strength agent (including triethanolamine: calcium nitrate = 1:42.5, i.e., 0.126 parts triethanolamine and 5.373 parts calcium nitrate). Solution B comprises the following components in parts by weight: 15 parts iron-based LDHs, 3.25 parts nano silica sol, 6.375 parts nano montmorillonite, and 0.4 parts dispersant; The preparation method of the above-mentioned grouting material includes the following steps: Step 1: Add 840 parts of silicate cement clinker, 80 parts of sulfoaluminate cement clinker, 24 parts of dihydrate gypsum, and 56 parts of anhydrite to a ball mill or vertical mill for co-grinding.

[0048] Step 2: Add the obtained composite cement base material, 250 parts fly ash, and 75 parts silica fume into a forced dry powder mixer and dry mix at high speed for 6.5 minutes.

[0049] Step 3: Pour the measured mixing water into the mixing tank at a water-to-binder ratio of 0.325, and then add 12.5 parts of polycarboxylate superplasticizer, 0.126 parts of triethanolamine, and 5.373 parts of calcium nitrate in sequence to prepare a solution.

[0050] Step 4: While stirring at a low speed of 250 rpm, slowly add the dry powder to the solution and stir at low speed for 7.5 minutes until the dry powder is completely wetted. After the addition is complete, switch to high speed stirring and shearing at 1000 rpm for 4 minutes to obtain solution A.

[0051] Step 5: Prepare iron-based LDHs.

[0052] Step 5-1, Prepare solution 1: Dissolve calcium nitrate tetrahydrate and ferric nitrate nonahydrate in 50 mL of deionized water at a molar ratio of 2:1.

[0053] Step 5-2, prepare solution 2: It is made by mixing NaOH and alcohol.

[0054] Step 5-3: Under magnetic stirring at 400 rpm, add solution 1 dropwise to solution 2 and continue magnetic stirring for 22 hours. After the reaction is complete, centrifuge the mixture multiple times and wash with deionized water until neutral.

[0055] Step 5-4, then place in a vacuum drying oven and dry at 77.5 ℃ for 11 hours.

[0056] Step 5-5: Grind the dried solid into powder using a ball mill to obtain LDHs-CF.

[0057] Steps 5-6, preparing solution 3: Dissolve calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate in 100 mL of deionized water in a molar ratio of 10:1:4.

[0058] Steps 5-7, preparing solution 4: Dissolve NaOH and NaNO3 in 100 mL of deionized water.

[0059] Steps 5-8: Add solutions 3 and 4 dropwise simultaneously into a three-necked flask containing a certain amount of alcohol and NaOH, and stir magnetically at 400 rpm for 2.5 hours.

[0060] Steps 5-9: Transfer the obtained mixture to an autoclave and crystallize at 105 °C for 18 hours. After the reaction, centrifuge multiple times and wash until neutral.

[0061] Steps 5-10: Dry in a vacuum drying oven at 77.5 ℃ for 11 hours, then grind into powder to obtain LDHs-CFA.

[0062] Steps 5-11: Take 8.2 parts of LDHs-CF and 6.8 parts of LDHs-CFA and mix them to obtain iron-based LDHs.

[0063] Step 6: Take 3.25 parts of nano-silica sol and 6.375 parts of nano-montmorillonite at a solid-liquid ratio of 1:25, mix them with 15 parts of the iron-based bimetallic hydroxide prepared in Step 6, and add them to deionized water. At the same time, add 0.4 parts of dispersant.

[0064] Step 7: Use a 400W ultrasonic disperser to perform ultrasonic treatment for 75 seconds to fully disperse the nanoparticles in water, thus obtaining solution B.

[0065] Step 8: Slowly add liquid A to liquid B, stir evenly, and then form the grouting material.

[0066] Example 2 A grouting material with anti-permeability and anti-corrosion properties suitable for engineering in chloride salt environments, comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is 9.

[0067] Liquid A comprises the following components in parts by weight: 840 parts silicate cement clinker, 90 parts sulfoaluminate cement clinker, 90 parts gypsum (including 39 parts dihydrate gypsum and 51 parts anhydrite), 300 parts fly ash, 100 parts silica fume, 15 parts polycarboxylate superplasticizer, and 8 parts early strength agent (including triethanolamine: calcium nitrate = 1:55, i.e., 0.142 parts triethanolamine and 7.858 parts calcium nitrate). Solution B comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide, 3.5 parts of nano-silica sol, 6.75 parts of nano-montmorillonite, and 0.5 parts of dispersant.

[0068] Step 1: Add 840 parts of silicate cement clinker, 90 parts of sulfoaluminate cement clinker, 39 parts of dihydrate gypsum, and 51 parts of anhydrite to a ball mill or vertical mill for co-grinding.

[0069] Step 2: Add the obtained composite cement base material, 300 parts fly ash, and 100 parts silica fume into a forced dry powder mixer and dry mix at high speed for 8 minutes.

[0070] Step 3: Pour the measured mixing water into the mixing tank at a water-to-binder ratio of 0.35, and then add 15 parts of polycarboxylate superplasticizer, 0.142 parts of triethanolamine and 7.858 parts of calcium nitrate in sequence to prepare a solution.

[0071] Step 4: While stirring at a low speed of 300 rpm, slowly add the dry powder to the solution and stir at low speed until the dry powder is completely wetted. After the addition is complete, switch to high speed stirring and shearing at 1200 rpm for 5 minutes to obtain solution A.

[0072] Step 5: Prepare iron-based LDHs.

[0073] Step 5-1, Prepare solution 1: Dissolve calcium nitrate tetrahydrate and ferric nitrate nonahydrate in 50 mL of deionized water at a molar ratio of 2:1.

[0074] Step 5-2, prepare solution 2: It is made by mixing NaOH and alcohol.

[0075] Step 5-3: Under magnetic stirring at 500 rpm, add solution 1 dropwise to solution 2 and continue magnetic stirring for 24 hours. After the reaction is complete, centrifuge the mixture multiple times and wash with deionized water until neutral.

[0076] Step 5-4, then place in a vacuum drying oven and dry at 80 ℃ for 12 hours.

[0077] Step 5-5: Grind the dried solid into powder using a ball mill to obtain LDHs-CF.

[0078] Steps 5-6, preparing solution 3: Dissolve calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate in 100 mL of deionized water in a molar ratio of 10:1:4.

[0079] Steps 5-7, preparing solution 4: Dissolve NaOH and NaNO3 in 100 mL of deionized water.

[0080] Steps 5-8: Add solutions 3 and 4 dropwise into a three-necked flask containing a certain amount of alcohol and NaOH, and stir magnetically at 500 rpm for 3 hours.

[0081] Steps 5-9: Transfer the obtained mixture to an autoclave and crystallize at 110 °C for 19 hours. After the reaction, centrifuge multiple times and wash until neutral.

[0082] Steps 5-10: Dry in a vacuum drying oven at 80 ℃ for 12 hours, then grind into powder to obtain LDHs-CFA.

[0083] Step 6: Take 3 parts of nano-silica sol and 6.75 parts of nano-montmorillonite at a solid-liquid ratio of 1:25, mix them with 15 parts of the iron-based bimetallic hydroxide prepared in Step 5, and add them to deionized water. At the same time, add 0.5 parts of dispersant.

[0084] Step 7: Use a 500W ultrasonic disperser to perform ultrasonic treatment for 90 seconds to fully disperse the nanoparticles in water, thus obtaining solution B.

[0085] Step 8: Slowly add liquid A to liquid B, stir evenly, and then form the grouting material.

[0086] Example 3 A grouting material with anti-permeability and anti-corrosion properties suitable for engineering in chloride salt environments, comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is 10; Liquid A has the same composition as in Example 1.

[0087] Solution B comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide, 3.25 parts of nano-silica sol, 6.75 parts of nano-montmorillonite, and 0.4 parts of dispersant.

[0088] In the preparation method of the anti-permeability and anti-corrosion grouting material suitable for engineering in chloride salt environment in this embodiment, steps 1-4 are completely consistent with those in Example 1, and liquid A is obtained.

[0089] Step 5: Prepare LDHs-CF and LDHs-CFA according to the method in Example 1. Take 8.2 parts of LDHs-CF and 6.5 parts of LDHs-CFA and mix them to prepare iron-based LDHs.

[0090] Step 6: Mix 3.25 parts of nano-silica sol, 6.75 parts of nano-montmorillonite, and 15 parts of the iron-based bimetallic hydroxide prepared in Step 5 at a solid-liquid ratio of 1:25, and add them to deionized water. At the same time, add 0.4 parts of dispersant.

[0091] Step 7: Use a 400W ultrasonic disperser to perform ultrasonic treatment for 75 seconds to fully disperse the nanoparticles in water, thus obtaining solution B.

[0092] Step 8: Slowly add liquid A to liquid B, stir evenly, and then form the grouting material.

[0093] Example 4 A grouting material with anti-permeability and anti-corrosion properties suitable for engineering in chloride salt environments, comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is 8.5.

[0094] Liquid A comprises the following components in parts by weight: 840 parts silicate cement clinker, 70 parts sulfoaluminate cement clinker, 70 parts gypsum (including 30 parts dihydrate gypsum and 49 parts anhydrite), 200 parts fly ash, 50 parts silica fume, 10 parts polycarboxylate superplasticizer, and 3 parts early strength agent (including triethanolamine: calcium nitrate = 1:30, i.e., 0.1 parts triethanolamine and 2.9 parts calcium nitrate).

[0095] Solution B comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide, 3.25 parts of nano-silica sol, 6.75 parts of nano-montmorillonite, and 0.5 parts of dispersant.

[0096] The method for preparing the anti-permeability and anti-corrosion grouting material suitable for engineering in chloride-salt environments in this embodiment includes the following steps: Step 1: Add 840 parts of silicate cement clinker, 70 parts of sulfoaluminate cement clinker, 30 parts of dihydrate gypsum, and 40 parts of anhydrite to a ball mill or vertical mill for co-grinding.

[0097] Step 2: Add the obtained composite cement substrate, 200 parts fly ash, and 50 parts silica fume into a forced dry powder mixer and dry mix at high speed for 5 minutes.

[0098] Step 3: Pour the measured mixing water into the mixing tank at a water-to-binder ratio of 0.3, and then add 10 parts of polycarboxylate superplasticizer, 0.1 parts of triethanolamine and 2.9 parts of calcium nitrate in sequence to prepare a solution.

[0099] Step 4: While stirring at a low speed of 200 rpm, slowly add the dry powder to the solution and stir at low speed for 5 minutes until the dry powder is completely wetted. After the addition is complete, switch to high speed stirring and shearing at 800 rpm for 3 minutes to obtain solution A.

[0100] Step 5: Prepare iron-based LDHs.

[0101] Step 5-1, Prepare solution 1: Dissolve calcium nitrate tetrahydrate and ferric nitrate nonahydrate in 50 mL of deionized water at a molar ratio of 2:1.

[0102] Step 5-2, prepare solution 2: It is made by mixing NaOH and alcohol.

[0103] Step 5-3: Under magnetic stirring at 300 rpm, add solution 1 dropwise to solution 2 and continue magnetic stirring for 20 hours. After the reaction is complete, centrifuge the mixture multiple times and wash with deionized water until neutral.

[0104] Step 5-4, then place in a vacuum drying oven and dry at 75 ℃ for 10 hours.

[0105] Step 5-5: Grind the dried solid into powder using a ball mill to obtain LDHs-CF.

[0106] Steps 5-6, preparing solution 3: Dissolve calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate in 100 mL of deionized water in a molar ratio of 10:1:4.

[0107] Steps 5-7, preparing solution 4: Dissolve NaOH and NaNO3 in 100 mL of deionized water.

[0108] Steps 5-8: Add solutions 3 and 4 dropwise into a three-necked flask containing a certain amount of alcohol and NaOH, and stir magnetically at 300 rpm for 20 hours.

[0109] Steps 5-9: Transfer the obtained mixture to an autoclave and crystallize at 100 °C for 17 hours. After the reaction, centrifuge multiple times and wash until neutral.

[0110] Steps 5-10: Dry in a vacuum drying oven at 75 ℃ for 10 hours, then grind into powder to obtain LDHs-CFA.

[0111] Steps 5-11: Take 8.2 parts of LDHs-CF and 6.8 parts of LDHs-CFA and mix them to obtain iron-based LDHs.

[0112] Step 6: Take 3.25 parts of nano silica sol and 6.75 parts of nano montmorillonite at a solid-liquid ratio of 1:25, mix them with 15 parts of the iron-based bimetallic hydroxide prepared in Step 6, and add them to deionized water. At the same time, add 0.4 parts of dispersant.

[0113] Step 7: Use a 300W ultrasonic disperser to perform ultrasonic treatment for 60 seconds to fully disperse the nanoparticles in water and obtain solution B.

[0114] Step 8: Slowly add liquid A to liquid B, stir evenly, and then form the grouting material.

[0115] Example 5 A grouting material with anti-permeability and anti-corrosion properties suitable for engineering in chloride salt environments, comprising liquid A and liquid B, wherein the weight ratio of liquid A to liquid B is 9.5.

[0116] Liquid A has the same composition as in Example 1.

[0117] Solution B comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide, 3 parts of nano-silica sol, and 6 parts of nano-montmorillonite.

[0118] In the preparation method of the anti-permeability and anti-corrosion grouting material suitable for engineering in chloride salt environment in this embodiment, steps 1-6 are completely consistent with those in Example 1, and iron-based LDHs are obtained.

[0119] Step 6: Mix 3 parts of nano-silica sol, 6 parts of nano-montmorillonite, and 15 parts of the iron-based bimetallic hydroxide prepared in Step 6 at a solid-liquid ratio of 1:25 and add them to deionized water, along with 0.6 parts of dispersant.

[0120] Steps 7-8 are completely consistent with Example 1, and the grouting material is obtained.

[0121] Performance testing The materials thoroughly mixed in Examples 1-5 were poured into five sets of molds for molding. Five sets of triple mold specimens (40mm×40mm×160mm) were prepared from each set. The specimens were cured in a standard curing chamber at a temperature of 20±2℃ and a relative humidity of over 95%. The specimens were then used for 7-day and 28-day compressive strength and free chloride ion concentration tests to evaluate the mechanical properties and corrosion resistance of the grouting material in a chloride salt environment.

[0122] Compressive strength test method: At 7 days and 28 days of curing, the cured specimens are removed, surface moisture is wiped off, and they are placed in the center of the bearing plate of the universal testing machine. The testing machine continuously and uniformly loads the specimen at a constant speed of 2 mm / min until the specimen fails. The instrument automatically records the maximum failure load that the specimen can withstand. The average value of the test results of three parallel specimens is taken as the final compressive strength value.

[0123] Test method for free chloride ion content: Soak the slurry sample block cured for 28 days in a 10wt% high-concentration NaCl solution for 30 days. After soaking, crush the sample block, grind it into fine powder using a pulverizer, and pass it through a 0.08mm square hole sieve. Take the sieve-passing material as the test sample. Place the weighed powder sample in deionized water and soak and shake it to fully dissolve the free chloride ions in the water. Use a 0.01 mol / L silver nitrate (AgNO3) standard solution as the titrant. Use a chloride ion selective electrode to monitor the potential change. When the titration reaches the equivalence point, record the volume of silver nitrate solution consumed, and then calculate the chloride ion concentration in the solution.

[0124] Calculation formula: ; in, W The content of free chloride ions in cement-based materials (%) C t The concentration of free chloride ions in the solution as determined by titration (mol / L); C w The background chloride ion concentration (mol / L) in deionized water. VThe volume of the solution measured is (L). m 35.5 represents the mass (g) of the slurry sample used for testing; 35.5 represents the molar mass of chlorine (g / mol).

[0125] The compressive strength and free chloride ion content after chloride salt corrosion were used to evaluate the corrosion resistance of the grouting material. The test results are shown in Table 1.

[0126] Table 1 shows the performance of anti-permeability and corrosion-resistant grouting materials suitable for chloride salt environments;

[0127] As shown in Table 1, the 7-day compressive strength of the grouting material of the present invention in Examples 1-5 is between 62.15-70.22 MPa, the 28-day compressive strength is between 70.55-78.55 MPa, and the free chloride ion content is between 0.298%-0.329%. Therefore, it is evident that the grouting material of the present invention, suitable for chloride-salt environments and resistant to permeation and corrosion, not only possesses excellent mechanical properties, meeting the strength requirements for rapid repair in chloride-salt environments, but also has good chloride ion adsorption and locking capabilities, effectively reducing the free chloride ion content within the material. This achieves rapid repair and chloride-salt corrosion resistance in chloride-salt environments, enabling long-term service in such environments.

[0128] Compared with Example 1, Example 5 reduced the content of nano-silica sol and nano-montmorillonite in solution B, resulting in a decrease in the micropore filling effect and pore tortuosity of the material, and a decrease in the ability to physically block chloride ion penetration. Therefore, the compressive strength at 7d and 28d was lower than that of Example 1, while the free chloride ion content was higher than that of Example 1. This indicates that the micro-filling effect of nanoparticles is the key to improving the material's resistance to chloride salt penetration.

[0129] The silicate-sulfoaluminate composite cement system of this invention provides core mechanical support for applications in chloride environments. Sulfoaluminate cement provides high early strength to meet rapid repair needs, while silicate cement ensures sustained strength growth in later stages, guaranteeing long-term engineering service. Needle-shaped ettringite formed by sulfoaluminate hydration creates a spatial framework, while CSH gel generated from silicate cement and silica fume fills the voids in the framework, improving material density. The rapid dissolution of dihydrate gypsum inhibits early setting, ensuring workability; the later dissolution of anhydrite ensures the stability of ettringite, increases slurry density, and reduces chloride ion penetration channels.

[0130] Fly ash undergoes a secondary hydration reaction with cement hydration products, replacing part of the cement to reduce the heat of hydration. Simultaneously, its micro-powder effect fills pores, and the micro-expansion of the composite system reduces shrinkage cracks, preventing chloride ions from penetrating through these cracks. The extremely fine particles of silica fume fill cement gaps and react with hydration products to form high-density CSH gel, further enhancing the compactness of the slurry and strengthening the physical barrier against chloride ions.

[0131] In the early strength agent, triethanolamine and calcium nitrate work synergistically to promote early hydration of cement, rapidly improve material strength, ensure the rapid repair capability of the project in a chloride salt environment, and reduce chloride salt erosion of the project in the unformed stage.

[0132] Iron-based LDHs can utilize interlayer nitrate ions to exchange with externally invading chloride ions, thereby locking harmful chloride ions within the material layers and achieving active chemical corrosion resistance. Simultaneously, their two-dimensional micro / nanosheet structure increases the tortuosity of the capillaries within cement-based materials, physically hindering the transport of water and chloride ions, achieving dual physical and chemical chloride ion protection. Furthermore, iron-based LDHs exhibit structural stability in the highly alkaline environment of cement-based materials, demonstrate good compatibility with the cement matrix, and are suitable for long-term application in chloride-rich environments.

[0133] Nano-silica sol can fill the micropores of cement-based materials. The sheet-like structure of nano-montmorillonite synergistically increases the tortuosity of the pores with the LDHs sheets, which greatly lengthens the chloride ion permeation path and significantly slows down the permeation rate. The synergistic effect of nanoparticles and iron-based LDHs gives the material excellent resistance to chloride ion permeation and chloride ion capture ability.

[0134] The A solution of this invention constructs a high-strength macroscopic mechanical framework through the hydration reaction of the cementing material. Its highly dense structure reduces the total amount of chloride ions penetrating from a physical perspective, achieving passive protection. Meanwhile, the iron-based LDHs in the B solution chemically capture and lock in the penetrating chloride ions through an ion exchange mechanism. At the same time, the nanoparticles in the B solution fill the pores generated by the A solution at the microscale in multiple stages, further improving the material density and enhancing the passive barrier effect.

[0135] In this invention, liquid A ensures the material possesses excellent workability, controllable setting time, and high early strength, enabling rapid repair of projects in chloride-contaminated environments. Liquid B, without compromising these workability properties, endows the material with excellent impermeability and chloride-contaminated corrosion resistance. The synergistic effect of the two liquids makes the grouting material of this invention suitable for grouting reinforcement and long-term protection in various chloride-contaminated environments, and it can be widely applied to engineering repair and reinforcement in marine, coastal, inland salt lake, saline soil, and chemical chloride-contaminated areas.

[0136] The embodiments described in this specification are merely examples of implementations of the inventive concept and are for illustrative purposes only. The scope of protection of this invention should not be considered limited to the specific forms described in these embodiments; rather, it extends to equivalent technical means conceived by those skilled in the art based on the inventive concept.

Claims

1. A grouting material suitable for chloride-salt environments that resists permeation and corrosion, characterized in that, The grouting material includes liquid A and liquid B, with a weight ratio of liquid A to liquid B of (8-10):1; The A liquid comprises the following components in parts by weight: 840 parts of silicate cement clinker, 70-90 parts of sulfoaluminate cement clinker, 70-90 parts of gypsum, 200-300 parts of fly ash, 50-100 parts of silica fume, 10-15 parts of water-reducing agent, and 3-8 parts of early-strength agent. The B solution comprises the following components in parts by weight: 15 parts of iron-based bimetallic hydroxide, 3-3.5 parts of nano-silica sol, 6-6.75 parts of nano-montmorillonite, and 0.4-0.6 parts of dispersant.

2. The anti-permeability and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1, characterized in that, The gypsum is a mixture of dihydrate gypsum and anhydrite, with a weight ratio of 3:6.5-7.

3. The anti-permeability and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1 or 2, characterized in that, The early strength agent is a compound of triethanolamine and calcium nitrate, wherein the weight ratio of triethanolamine to calcium nitrate is 1:(30-55).

4. The anti-permeability and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1 or 2, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent, and the water-cement ratio of the A solution is 0.30-0.

35.

5. The anti-permeability and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1 or 2, characterized in that, The iron-based bimetallic hydroxide is made by mixing LDHs-CF and LDHs-CFA in a mass ratio of 6:4.5-5.

6. The anti-permeability and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1 or 2, characterized in that, The average particle size of the nano-silica sol is 10-30 nm; the average particle size of the nano-montmorillonite is 80-100 nm.

7. A method for preparing a permeation-resistant and corrosion-resistant grouting material suitable for chloride salt environments as described in claim 1, characterized in that, The preparation method includes the following steps: Step 1: Put silicate cement clinker, sulfoaluminate cement clinker and anhydrite into a ball mill or vertical mill for co-grinding in a certain proportion; Step 2: Add the obtained composite cement base material, fly ash, and silica fume into a forced dry powder mixer and dry mix them evenly at high speed. Step 3: Pour the measured mixing water into the mixing tank according to the water-to-binder ratio of 0.30-0.35, and add polycarboxylate superplasticizer, calcium nitrate and triethanolamine in sequence to prepare a solution; Step 4: While stirring at low speed, slowly add the dry powder to the solution and stir at low speed until the dry powder is completely wetted. After the addition is completed, switch to high speed stirring and shearing to obtain solution A. Step 5: Mix LDHs-CF and LDHs-CFA at a mass ratio of 6:4.5-5 to obtain an iron-based bimetallic hydroxide. Step 6: Add nano silica sol, nano montmorillonite and iron-based bimetallic hydroxide to deionized water at a solid-liquid ratio of 1:20-1:30 and mix with a dispersant. Step 7: Use an ultrasonic disperser to perform ultrasonic treatment to fully disperse the nanoparticles in water, obtaining solution B; Step 8: Add liquid A to liquid B according to the set ratio, stir evenly, and then form the grouting material.

8. The preparation method according to claim 7, characterized in that, In step 5, the preparation process of LDHs-CF is as follows: calcium nitrate tetrahydrate and ferric nitrate nonahydrate are dissolved in deionized water according to a set molar ratio to prepare solution 1, and NaOH and alcohol are mixed to prepare mixed solution 2; under magnetic stirring, solution 1 is added dropwise to solution 2 according to a set volume ratio, and magnetic stirring is continued. After the reaction is completed, the mixture is centrifuged multiple times, washed with deionized water until neutral, and then dried in a vacuum drying oven and ground into powder to obtain LDHs-CF.

9. The preparation method according to claim 7 or 8, characterized in that, In step 5, calcium nitrate tetrahydrate, ferric nitrate nonahydrate, and aluminum nitrate nonahydrate are dissolved in deionized water according to a set molar ratio to prepare solution 3, and NaOH and NaNO3 are dissolved in deionized water to prepare solution 4. Solutions 3 and 4 are added dropwise to a three-necked flask containing alcohol and NaOH according to a set volume ratio, and the mixture is magnetically stirred. The mixture is then transferred to an autoclave and crystallized at a set temperature. After the reaction, the mixture is centrifuged multiple times and washed until neutral. It is then dried in a vacuum drying oven and ground into powder to obtain LDHs-CFA.

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